Sample records for acinetobacter baylyi strain
-
Improved triacylglycerol production in Acinetobacter baylyi ADP1 by metabolic engineering.
Santala, Suvi; Efimova, Elena; Kivinen, Virpi; Larjo, Antti; Aho, Tommi; Karp, Matti; Santala, Ville
2011-05-18
Triacylglycerols are used in various purposes including food applications, cosmetics, oleochemicals and biofuels. Currently the main sources for triacylglycerol are vegetable oils, and microbial triacylglycerol has been suggested as an alternative for these. Due to the low production rates and yields of microbial processes, the role of metabolic engineering has become more significant. As a robust model organism for genetic and metabolic studies, and for the natural capability to produce triacylglycerol, Acinetobacter baylyi ADP1 serves as an excellent organism for modelling the effects of metabolic engineering for energy molecule biosynthesis. Beneficial gene deletions regarding triacylglycerol production were screened by computational means exploiting the metabolic model of ADP1. Four deletions, acr1, poxB, dgkA, and a triacylglycerol lipase were chosen to be studied experimentally both separately and concurrently by constructing a knock-out strain (MT) with three of the deletions. Improvements in triacylglycerol production were observed: the strain MT produced 5.6 fold more triacylglycerol (mg/g cell dry weight) compared to the wild type strain, and the proportion of triacylglycerol in total lipids was increased by 8-fold. In silico predictions of beneficial gene deletions were verified experimentally. The chosen single and multiple gene deletions affected beneficially the natural triacylglycerol metabolism of A. baylyi ADP1. This study demonstrates the importance of single gene deletions in triacylglycerol metabolism, and proposes Acinetobacter sp. ADP1 as a model system for bioenergetic studies regarding metabolic engineering.
-
Suárez, Gabriel A.; Renda, Brian A.; Dasgupta, Aurko
2017-01-01
ABSTRACT The genomes of most bacteria contain mobile DNA elements that can contribute to undesirable genetic instability in engineered cells. In particular, transposable insertion sequence (IS) elements can rapidly inactivate genes that are important for a designed function. We deleted all six copies of IS1236 from the genome of the naturally transformable bacterium Acinetobacter baylyi ADP1. The natural competence of ADP1 made it possible to rapidly repair deleterious point mutations that arose during strain construction. In the resulting ADP1-ISx strain, the rates of mutations inactivating a reporter gene were reduced by 7- to 21-fold. This reduction was higher than expected from the incidence of new IS1236 insertions found during a 300-day mutation accumulation experiment with wild-type ADP1 that was used to estimate spontaneous mutation rates in the strain. The extra improvement appears to be due in part to eliminating large deletions caused by IS1236 activity, as the point mutation rate was unchanged in ADP1-ISx. Deletion of an error-prone polymerase (dinP) and a DNA damage response regulator (umuDAb [the umuD gene of A. baylyi]) from the ADP1-ISx genome did not further reduce mutation rates. Surprisingly, ADP1-ISx exhibited increased transformability. This improvement may be due to less autolysis and aggregation of the engineered cells than of the wild type. Thus, deleting IS elements from the ADP1 genome led to a greater than expected increase in evolutionary reliability and unexpectedly enhanced other key strain properties, as has been observed for other clean-genome bacterial strains. ADP1-ISx is an improved chassis for metabolic engineering and other applications. IMPORTANCE Acinetobacter baylyi ADP1 has been proposed as a next-generation bacterial host for synthetic biology and genome engineering due to its ability to efficiently take up DNA from its environment during normal growth. We deleted transposable elements that are capable of copying themselves
-
Suárez, Gabriel A; Renda, Brian A; Dasgupta, Aurko; Barrick, Jeffrey E
2017-09-01
The genomes of most bacteria contain mobile DNA elements that can contribute to undesirable genetic instability in engineered cells. In particular, transposable insertion sequence (IS) elements can rapidly inactivate genes that are important for a designed function. We deleted all six copies of IS 1236 from the genome of the naturally transformable bacterium Acinetobacter baylyi ADP1. The natural competence of ADP1 made it possible to rapidly repair deleterious point mutations that arose during strain construction. In the resulting ADP1-ISx strain, the rates of mutations inactivating a reporter gene were reduced by 7- to 21-fold. This reduction was higher than expected from the incidence of new IS 1236 insertions found during a 300-day mutation accumulation experiment with wild-type ADP1 that was used to estimate spontaneous mutation rates in the strain. The extra improvement appears to be due in part to eliminating large deletions caused by IS 1236 activity, as the point mutation rate was unchanged in ADP1-ISx. Deletion of an error-prone polymerase ( dinP ) and a DNA damage response regulator ( umuD Ab [the umuD gene of A. baylyi ]) from the ADP1-ISx genome did not further reduce mutation rates. Surprisingly, ADP1-ISx exhibited increased transformability. This improvement may be due to less autolysis and aggregation of the engineered cells than of the wild type. Thus, deleting IS elements from the ADP1 genome led to a greater than expected increase in evolutionary reliability and unexpectedly enhanced other key strain properties, as has been observed for other clean-genome bacterial strains. ADP1-ISx is an improved chassis for metabolic engineering and other applications. IMPORTANCE Acinetobacter baylyi ADP1 has been proposed as a next-generation bacterial host for synthetic biology and genome engineering due to its ability to efficiently take up DNA from its environment during normal growth. We deleted transposable elements that are capable of copying themselves
-
Leong, Colleen G; Boyd, Caroline M; Roush, Kaleb S; Tenente, Ricardo; Lang, Kristine M; Lostroh, C Phoebe
2017-10-01
Natural transformation is the acquisition of new genetic material via the uptake of exogenous DNA by competent bacteria. Acinetobacter baylyi is model for natural transformation. Here we focus on the natural transformation of A. baylyi ATCC 33305 grown in complex media and seek environmental conditions that appreciably affect transformation efficiency. We find that the transformation efficiency for A. baylyi is a resilient characteristic that remains high under most conditions tested. We do find several distinct conditions that alter natural transformation efficiency including addition of succinate, Fe 2+ (ferrous) iron chelation, and substitution of sodium ions with potassium ones. These distinct conditions could be useful to fine tune transformation efficiency for researchers using A. baylyi as a model organism to study natural transformation.
-
Costs and benefits of natural transformation in Acinetobacter baylyi.
Hülter, Nils; Sørum, Vidar; Borch-Pedersen, Kristina; Liljegren, Mikkel M; Utnes, Ane L G; Primicerio, Raul; Harms, Klaus; Johnsen, Pål J
2017-02-15
Natural transformation enables acquisition of adaptive traits and drives genome evolution in prokaryotes. Yet, the selective forces responsible for the evolution and maintenance of natural transformation remain elusive since taken-up DNA has also been hypothesized to provide benefits such as nutrients or templates for DNA repair to individual cells. We investigated the immediate effects of DNA uptake and recombination on the naturally competent bacterium Acinetobacter baylyi in both benign and genotoxic conditions. In head-to-head competition experiments between DNA uptake-proficient and -deficient strains, we observed a fitness benefit of DNA uptake independent of UV stress. This benefit was found with both homologous and heterologous DNA and was independent of recombination. Recombination with taken-up DNA reduced survival of transformed cells with increasing levels of UV-stress through interference with nucleotide excision repair, suggesting that DNA strand breaks occur during recombination attempts with taken-up DNA. Consistent with this, we show that absence of RecBCD and RecFOR recombinational DNA repair pathways strongly decrease natural transformation. Our data show a physiological benefit of DNA uptake unrelated to recombination. In contrast, recombination during transformation is a strand break inducing process that represents a previously unrecognized cost of natural transformation.
-
A complete collection of single-gene deletion mutants of Acinetobacter baylyi ADP1
de Berardinis, Véronique; Vallenet, David; Castelli, Vanina; Besnard, Marielle; Pinet, Agnès; Cruaud, Corinne; Samair, Sumitta; Lechaplais, Christophe; Gyapay, Gabor; Richez, Céline; Durot, Maxime; Kreimeyer, Annett; Le Fèvre, François; Schächter, Vincent; Pezo, Valérie; Döring, Volker; Scarpelli, Claude; Médigue, Claudine; Cohen, Georges N; Marlière, Philippe; Salanoubat, Marcel; Weissenbach, Jean
2008-01-01
We have constructed a collection of single-gene deletion mutants for all dispensable genes of the soil bacterium Acinetobacter baylyi ADP1. A total of 2594 deletion mutants were obtained, whereas 499 (16%) were not, and are therefore candidate essential genes for life on minimal medium. This essentiality data set is 88% consistent with the Escherichia coli data set inferred from the Keio mutant collection profiled for growth on minimal medium, while 80% of the orthologous genes described as essential in Pseudomonas aeruginosa are also essential in ADP1. Several strategies were undertaken to investigate ADP1 metabolism by (1) searching for discrepancies between our essentiality data and current metabolic knowledge, (2) comparing this essentiality data set to those from other organisms, (3) systematic phenotyping of the mutant collection on a variety of carbon sources (quinate, 2-3 butanediol, glucose, etc.). This collection provides a new resource for the study of gene function by forward and reverse genetic approaches and constitutes a robust experimental data source for systems biology approaches. PMID:18319726
-
Sigala, Juan-Carlos; Suárez, Brisa Paola; Lara, Alvaro R; Borgne, Sylvie Le; Bustos, Patricia; Santamaría, Rosa Isela; González, Víctor; Martinez, Alfredo
2017-07-01
An Acinetobacter strain, designated ACE, was isolated in the laboratory. Phylogenetic tests and average nucleotide identity value comparisons suggested that ACE belongs to the species Acinetobacterschindleri. We report for the first time the complete genome sequence of an A. schindleri strain, which consists of a single circular chromosome of 3 001 209 bp with an overall DNA G+C content of 42.9 mol% and six plasmids that account for 266 844 bp of extrachromosomal material. The presence or absence of genes related to carbon catabolism and antibiotic resistance were in agreement with the phenotypic characterization of ACE. This strain grew faster and with a higher biomass yield on acetate than the reference strain Acinetobacter baylyi ADP1. However, ACE did not use aromatic compounds and was unable to grow on common carbon sources, such as glucose, xylose, glycerol or citrate. The gluconeogenic and the catechol pathways are complete in ACE, but compounds that are converted to protocatechuate did not sustain growth since some genes of this pathway are missing. Likewise, this strain could not grow on glucose because it lacks the genes of the Entner-Doudoroff pathway. Minimal inhibitory concentration data showed that ACE was susceptible to most of the antimicrobial agents recommended for the clinical treatment of Acinetobacter spp. Some genes related to a possible human-microbe interaction were found in the ACE genome. ACE is likely to have a low pathogenic risk, as is the case with other A. schindleri strains. These results provide a valuable reference for broadening the knowledge of the biology of Acinetobacter.
-
Staring at the cold sun: blue light regulation is distributed within the genus Acinetobacter.
Golic, Adrián; Vaneechoutte, Mario; Nemec, Alexandr; Viale, Alejandro M; Actis, Luis A; Mussi, María Alejandra
2013-01-01
We previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD)-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24°C, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24°C but also at 37°C in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24°C. Second, we show that Acinetobacter baylyi (strain ADP1) BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24°C between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility.
-
Staring at the Cold Sun: Blue Light Regulation Is Distributed within the Genus Acinetobacter
Golic, Adrián; Vaneechoutte, Mario; Nemec, Alexandr; Viale, Alejandro M.; Actis, Luis A.; Mussi, María Alejandra
2013-01-01
We previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD)-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24°C, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24°C but also at 37°C in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24°C. Second, we show that Acinetobacter baylyi (strain ADP1) BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24°C between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility. PMID:23358859
-
Complete Genome Sequence of the Diesel-Degrading Acinetobacter sp. Strain DR1 ▿
Jung, Jaejoon; Baek, Jeong-Hun; Park, Woojun
2010-01-01
The genus Acinetobacter is ubiquitous in soil, aquatic, and sediment environments and includes pathogenic strains, such as A. baumannii. Many Acinetobacter species isolated from various environments have biotechnological potential since they are capable of degrading a variety of pollutants. Acinetobacter sp. strain DR1 has been identified as a diesel degrader. Here we report the complete genome sequence of Acinetobacter sp. DR1 isolated from the soil of a rice paddy. PMID:20639327
-
Cho, Gyu-Sung; Li, Bo; Rostalsky, André; Fiedler, Gregor; Rösch, Niels; Igbinosa, Etinosa; Kabisch, Jan; Bockelmann, Wilhelm; Hammer, Philipp; Huys, Geert; Franz, Charles M. A. P.
2018-01-01
Forty-seven Acinetobacter spp. isolates from milk powder obtained from a powdered milk producer in Germany were investigated for their antibiotic resistance susceptibilities, in order to assess whether strains from food harbor multiple antibiotic resistances and whether the food route is important for dissemination of resistance genes. The strains were identified by 16S rRNA and rpoB gene sequencing, as well as by whole genome sequencing of selected isolates and their in silico DNA-DNA hybridization (DDH). Furthermore, they were genotyped by rep-PCR together with reference strains of pan-European groups I, II, and III strains of Acinetobacter baumannii. Of the 47 strains, 42 were identified as A. baumannii, 4 as Acinetobacter Pittii, and 1 as Acinetobacter calcoaceticus based on 16S rRNA gene sequencing. In silico DDH with the genome sequence data of selected strains and rpoB gene sequencing data suggested that the five non-A. baumannii strains all belonged to A. pittii, suggesting that the rpoB gene is more reliable than the 16S rRNA gene for species level identification in this genus. Rep-PCR genotyping of the A. baumannii strains showed that these could be grouped into four groups, and that some strains clustered together with reference strains of pan-European clinical group II and III strains. All strains in this study were intrinsically resistant toward chloramphenicol and oxacillin, but susceptible toward tetracycline, tobramycin, erythromycin, and ciprofloxacin. For cefotaxime, 43 strains (91.5%) were intermediate and 3 strains (6.4%) resistant, while 3 (6.4%) and 21 (44.7%) strains exhibited resistance to cefepime and streptomycin, respectively. Forty-six (97.9%) strains were susceptible to amikacin and ampicillin-sulbactam. Therefore, the strains in this study were generally not resistant to the clinically relevant antibiotics, especially tobramycin, ciprofloxacin, cefepime, and meropenem, suggesting that the food route probably poses only a low risk for
-
Coaggregation between Rhodococcus and Acinetobacter strains isolated from the food industry.
Møretrø, Trond; Sharifzadeh, Shahab; Langsrud, Solveig; Heir, Even; Rickard, Alexander H
2015-07-01
In this study, coaggregation interactions between Rhodococcus and Acinetobacter strains isolated from food-processing surfaces were characterized. Rhodococcus sp. strain MF3727 formed intrageneric coaggregates with Rhodococcus sp. strain MF3803 and intergeneric coaggregates with 2 strains of Acinetobacter calcoaceticus (MF3293, MF3627). Stronger coaggregation between A. calcoaceticus MF3727 and Rhodococcus sp. MF3293 was observed after growth in batch culture at 30 °C than at 20 °C, after growth in tryptic soy broth than in liquid R2A medium, and between cells in exponential and early stationary phases than cells in late stationary phase. The coaggregation ability of Rhodococcus sp. MF3727 was maintained even after heat and Proteinase K treatment, suggesting its ability to coaggregate was protein independent whereas the coaggregation determinants of the other strains involved proteinaceous cell-surface-associated polymers. Coaggregation was stable at pH 5-9. The mechanisms of coaggregation among Acinetobacter and Rhodococcus strains bare similarity to those displayed by coaggregating bacteria of oral and freshwater origin, with respect to binding between proteinaceous and nonproteinaceous determinants and the effect of environmental factors on coaggregation. Coaggregation may contribute to biofilm formation on industrial food surfaces, protecting bacteria against cleaning and disinfection.
-
Scholz, Anica; Stahl, Julia; de Berardinis, Veronique; Müller, Volker; Averhoff, Beate
2016-04-01
Acinetobacter baylyi, a ubiquitous soil bacterium, can cope with high salinity by uptake of choline as precursor of the compatible solute glycine betaine. Here, we report on the identification of a choline dehydrogenase (BetA) and a glycine betaine aldehyde dehydrogenase (BetB) mediating the oxidation of choline to glycine betaine. The betAB genes were found to form an operon together with the potential transcriptional regulator betI. The transcription of the betIBA operon and the two recently identified choline transporters was upregulated in response to choline and choline plus salt. The finding that the osmo-independent transporter BetT1 undergoes a higher upregulation in response to choline alone than betT2 suggests that BetT1 does not primarily function in osmoadaptation. Electrophoretic mobility shift assays led to the conclusion that BetI mediates transcriptional regulation of both, the betIBA gene operon and the choline transporters. BetI was released from the DNA in response to choline which together with the transcriptional upregulation of the bet genes in the presence of choline suggests that BetI is a choline sensing transcriptional repressor. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.
-
Nutritional Requirements of Acinetobacter Strains Isolated from Soil, Water, and Sewage
Warskow, Alice L.; Juni, Elliot
1972-01-01
One hundred five strains of Acinetobacter were isolated from water, soil, and sewage on nonselective complex media, and their nutritional properties were studied. Only one of these strains requires growth factors in order to grow in a mineral medium containing a single carbon source. PMID:4563966
-
Carvalho, Maria J.; Toleman, Mark A.; White, P. Lewis; Connor, Thomas R.; Mushtaq, Ammara; Weeks, Janis L.; Kumarasamy, Karthikeyan K.; Raven, Katherine E.; Török, M. Estée; Peacock, Sharon J.; Howe, Robin A.; Walsh, Timothy R.
2014-01-01
The blaNDM-1 gene is associated with extensive drug resistance in Gram-negative bacteria. This probably spread to Enterobacteriaceae from Acinetobacter spp., and we characterized plasmids associated with blaNDM-1 in Acinetobacter spp. to gain insight into their role in this dissemination. Four clinical NDM-1-producing Acinetobacter species strains from India and Pakistan were investigated. A plasmid harboring blaNDM-1, pNDM-40-1, was characterized by whole-genome sequencing of Acinetobacter bereziniae CHI-40-1 and comparison with related plasmids. The presence of similar plasmids in strains from Pakistan was sought by PCR and sequencing of amplicons. Conjugation frequency was tested and stability of pNDM-40-1 investigated by real-time PCR of isolates passaged with and without antimicrobial selection pressure. A. bereziniae and Acinetobacter haemolyticus strains contained plasmids similar to the pNDM-BJ01-like plasmids identified in Acinetobacter spp. in China. The backbone of pNDM-40-1 was almost identical to that of pNDM-BJ01-like plasmids, but the transposon harboring blaNDM-1, Tn125, contained two short deletions. Escherichia coli and Acinetobacter pittii transconjugants were readily obtained. Transconjugants retained pNDM-40-1 after a 14-day passage experiment, although stability was greater with meropenem selection. Fragments of pNDM-BJ01-like plasmid backbones are found near blaNDM-1 in some genetic contexts from Enterobacteriaceae, suggesting that cross-genus transfer has occurred. pNDM-BJ01-like plasmids have been described in isolates originating from a wide geographical region in southern Asia. In vitro data on plasmid transfer and stability suggest that these plasmids could have contributed to the spread of blaNDM-1 into Enterobacteriaceae. PMID:25421466
-
Analysis of drug resistance in 1,861 strains of Acinetobacter baumannii.
Jin, Hao; Qiu, Fan; Ji, Hong Jian; Lu, Qiang
2016-04-01
Acinetobacter baumannii is an emerging human pathogen that causes hospital-acquired infections. The trend in increased antimicrobial resistance limits the choice of effective antimicrobial agents. The present study reports the resistance to Acinetobacter baumannii and analyzes the associations between antibiotic use and resistance rates at a general hospital between 2010 and 2014. A total of 1,861 isolates were obtained from clinical cultures, accounting for 10.33% of all detected bacteria (1,861/18,016). The strains were mainly from respiratory samples (1,628 isolates, 87.5%) and the intensive care unit (696 isolates, 37.4%). The resistance rates of Acinetobacter baumannii to the majority of antibiotics were >50%, particularly the resistance rate to cefoperazone/sulbactam increased from 47.37 in 2011 to 89.25% in 2014. However, the rates of imipenem and cilastatin sodium decreased from 81.03 to 69.44% due to the antibiotic policy. There were Pearson significant associations between the use of three antibiotics and resistance in Acinetobacter baumannii to this drug, piperacillin/tazobactam (r=0.976, P<0.01), gentamicin (r=0.870, P<0.01) and cefoxitin (r=0.741, P<0.05). Therefore, a combination of drugs should be adopted to treat Acinetobacter baumannii infections. Microbiology laboratory support and surveillance policies are essential to control the emergence of multidrug-resistance Acinetobacter baumannii .
-
Colistin-Resistant Acinetobacter baumannii Clinical Strains with Deficient Biofilm Formation
Dafopoulou, Konstantina; Xavier, Basil Britto; Hotterbeekx, An; Janssens, Lore; Lammens, Christine; Dé, Emmanuelle; Goossens, Herman; Tsakris, Athanasios; Malhotra-Kumar, Surbhi
2015-01-01
In two pairs of clinical colistin-susceptible/colistin-resistant (Csts/Cstr) Acinetobacter baumannii strains, the Cstr strains showed significantly decreased biofilm formation in static and dynamic assays (P < 0.001) and lower relative fitness (P < 0.05) compared with those of the Csts counterparts. The whole-genome sequencing comparison of strain pairs identified a mutation converting a stop codon to lysine (*241K) in LpsB (involved in lipopolysaccharide [LPS] synthesis) in one Cstr strain and a frameshift mutation in CarO and the loss of a 47,969-bp element containing multiple genes associated with biofilm production in the other. PMID:26666921
-
Role of Cations in Accumulation and Release of Phosphate by Acinetobacter Strain 210A
van Groenestijn, Johan W.; Vlekke, Gerard J. F. M.; Anink, Désirée M. E.; Deinema, Maria H.; Zehnder, Alexander J. B.
1988-01-01
Cells of the strictly aerobic Acinetobacter strain 210A, containing aerobically large amounts of polyphosphate (100 mg of phosphorus per g [dry weight] of biomass), released in the absence of oxygen 1.49 mmol of Pi, 0.77 meq of Mg2+, 0.48 meq of K+, 0.02 meq of Ca2+, and 0.14 meq of NH4+ per g (dry weight) of biomass. The drop in pH during this anaerobic phase was caused by the release of 1.8 protons per PO43− molecule. Cells of Acinetobacter strain 132, which do not accumulate polyphosphate aerobically, released only 0.33 mmol of Pi and 0.13 meq of Mg2+ per g (dry weight) of biomass but released K+ in amounts comparable to those released by strain 210A. Stationary-phase cultures of Acinetobacter strain 210A, in which polyphosphate could not be detected by Neisser staining, aerobically took up phosphate simultaneously with Mg2+, the most important counterion in polyphosphate. In the absence of dissolved phosphate in the medium, no Mg2+ was taken up. Cells containing polyphosphate granules were able to grow in a Mg-free medium, whereas cells without these granules were not. Mg2+ was not essential as a counterion because it could be replaced by Ca2+. The presence of small amounts of K+ was essential for polyphosphate formation in cells of strain 210A. During continuous cultivation under K+ limitation, cells of Acinetobacter strain 210A contained only 14 mg of phosphorus per g (dry weight) of biomass, whereas this element was accumulated in amounts of 59 mg/g under substrate limitation and 41 mg/g under Mg2+ limitation. For phosphate uptake in activated sludge, the presence of K+ seemed to be crucial. PMID:16347788
-
Comparative genomic analysis of Acinetobacter strains isolated from murine colonic crypts.
Saffarian, Azadeh; Touchon, Marie; Mulet, Céline; Tournebize, Régis; Passet, Virginie; Brisse, Sylvain; Rocha, Eduardo P C; Sansonetti, Philippe J; Pédron, Thierry
2017-07-11
A restricted set of aerobic bacteria dominated by the Acinetobacter genus was identified in murine intestinal colonic crypts. The vicinity of such bacteria with intestinal stem cells could indicate that they protect the crypt against cytotoxic and genotoxic signals. Genome analyses of these bacteria were performed to better appreciate their biodegradative capacities. Two taxonomically different clusters of Acinetobacter were isolated from murine proximal colonic crypts, one was identified as A. modestus and the other as A. radioresistens. Their identification was performed through biochemical parameters and housekeeping gene sequencing. After selection of one strain of each cluster (A. modestus CM11G and A. radioresistens CM38.2), comparative genomic analysis was performed on whole-genome sequencing data. The antibiotic resistance pattern of these two strains is different, in line with the many genes involved in resistance to heavy metals identified in both genomes. Moreover whereas the operon benABCDE involved in benzoate metabolism is encoded by the two genomes, the operon antABC encoding the anthranilate dioxygenase, and the phenol hydroxylase gene cluster are absent in the A. modestus genomic sequence, indicating that the two strains have different capacities to metabolize xenobiotics. A common feature of the two strains is the presence of a type IV pili system, and the presence of genes encoding proteins pertaining to secretion systems such as Type I and Type II secretion systems. Our comparative genomic analysis revealed that different Acinetobacter isolated from the same biological niche, even if they share a large majority of genes, possess unique features that could play a specific role in the protection of the intestinal crypt.
-
Alvarez-Buylla, Adela; Culebras, Esther; Picazo, Juan J
2012-03-01
Acinetobacter spp. has become a leading cause of nosocomial infection in recent years. Phenotypic similarities between the species in the genus have made it difficult to identify them clearly using routine diagnostic methods. Consequently, more relevant species have been grouped together as Acinetobacter calcoaceticus-Acinetobacter baumannii complex (A. baumannii, A. calcoaceticus, Acinetobacter genospecies 3 and A. genospecies 13TU). However, there are other species that may also have clinical significance. The aims of this study were to establish the usefulness of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of Acinetobacter species by comparison with two molecular techniques, as well as determine the role of species other than A. baumannii play in nosocomial infections.The study sample comprised 109 clinical isolates of Acinetobacter. They were all identified using MALDI-TOF MS. Thirty-one isolates of these were also tested using comparator amplification of bla(OXA51-like) and sequencing of the rpoB gene. Different score values in MALDI-TOF MS revealed 87 A. baumannii, 19 A. genospecies 3, 1 Acinetobacter junii, 1 Acinetobacter baylyi and 1 Acinetobacter tjernbergiae. Amplification of bla(OXA-51)(-like) showed products in 85 isolates. Sequencing of the rpoB gene allowed us to identify all the 31 isolates analyzed: 16 were consistent with the results of spectrometry and 15 were not. This work showed that molecular techniques are still needed to identify the different species of clinical interest within the genus Acinetobacter. Although, MALDI-TOF MS could be useful to identify A. baumannii but not other species in the genus. Copyright © 2012 Elsevier B.V. All rights reserved.
-
Enrichment of Acinetobacter spp. from food samples.
Carvalheira, Ana; Ferreira, Vânia; Silva, Joana; Teixeira, Paula
2016-05-01
Relatively little is known about the role of foods in the chain of transmission of acinetobacters and the occurrence of different Acinetobacter spp. in foods. Currently, there is no standard procedure to recover acinetobacters from food in order to gain insight into the food-related ecology and epidemiology of acinetobacters. This study aimed to assess whether enrichment in Dijkshoorn enrichment medium followed by plating in CHROMagar™ Acinetobacter medium is a useful method for the isolation of Acinetobacter spp. from foods. Recovery of six Acinetobacter species from food spiked with these organisms was compared for two selective enrichment media (Baumann's enrichment and Dijkshoorn's enrichment). Significantly (p < 0.01) higher cell counts were obtained in Dijkshoorn's enrichment. Next, the Dijkshoorn's enrichment followed by direct plating on CHROMagar™ Acinetobacter was applied to detect Acinetobacter spp. in different foods. Fourteen different presumptive acinetobacters were recovered and assumed to represent nine different strains on the basis of REP-PCR typing. Eight of these strains were identified by rpoB gene analysis as belonging to the species Acinetobacter johnsonii, Acinetobacter calcoaceticus, Acinetobacter guillouiae and Acinetobacter gandensis. It was not possible to identify the species level of one strain which may suggests that it represents a distinct species. Copyright © 2015 Elsevier Ltd. All rights reserved.
-
Characterization of Acinetobacter baumannii strain PS3 in degradation of food emulsifiers
NASA Astrophysics Data System (ADS)
Nguyen, Ngoc Tuan; Tran, Tuyet Nhung; Ha, Thi Bich Ngoc
2018-04-01
Strain SP3 revealed the abilty to utilizes emulsifier which is widely used in the preparation of drugs, vaccines, food, cosmetics and skin care products as its sole carbon and energy source. Generation time ranges from 1.4 to 2.1 h on the polysorbate family. Strain was identified as Acinetobacter baumannii based on 16S rRNA gene and it could dispose 27 % polysorbate 80 within a day. The proposed mechanism for polysorbate utilization belongs to the β-oxidation.
-
Survival of Acinetobacter baumannii on dry surfaces.
Wendt, C; Dietze, B; Dietz, E; Rüden, H
1997-01-01
Acinetobacter spp. have frequently been reported to be the causative agents of hospital outbreaks. The circumstances of some outbreaks demonstrated the long survival of Acinetobacter in a dry, inanimate environment. In laboratory experiments, we compared the abilities of five Acinetobacter baumannii strains, three Acinetobacter sp. strains from the American Type Culture Collection (ATCC), one Escherichia coli ATCC strain, and one Enterococcus faecium ATCC strain to survive under dry conditions. Bacterial solutions of the 10 strains were inoculated onto four different material samples (ceramic, polyvinyl chloride, rubber, and stainless steel) and stored under defined conditions. We investigated the bacterial counts of the material samples immediately after inoculation, after drying, and after 4 h, 1 day, and 1, 2, 4, 8, and 16 weeks of storage. A statistical model was used to distribute the 40 resulting curves among four types of survival curves. The type of survival curve was significantly associated with the bacterial strain but not with the material. The ability of the A. baumannii strains to survive under dry conditions varied greatly and correlated well with the source of the strain. Strains isolated from dry sources survived better than those isolated from wet sources. An outbreak strain that had caused hospital-acquired respiratory tract infections survived better than the strains from wet sources, but not as well as strains from dry sources. Resistance to dry conditions may promote the transmissibility of a strain, but it is not sufficient to make a strain an epidemic one. However, in the case of an outbreak, sources of Acinetobacter must be expected in the dry environment. PMID:9163451
-
Genome organization of epidemic Acinetobacter baumannii strains.
Di Nocera, Pier Paolo; Rocco, Francesco; Giannouli, Maria; Triassi, Maria; Zarrilli, Raffaele
2011-10-10
Acinetobacter baumannii is an opportunistic pathogen responsible for hospital-acquired infections. A. baumannii epidemics described world-wide were caused by few genotypic clusters of strains. The occurrence of epidemics caused by multi-drug resistant strains assigned to novel genotypes have been reported over the last few years. In the present study, we compared whole genome sequences of three A. baumannii strains assigned to genotypes ST2, ST25 and ST78, representative of the most frequent genotypes responsible for epidemics in several Mediterranean hospitals, and four complete genome sequences of A. baumannii strains assigned to genotypes ST1, ST2 and ST77. Comparative genome analysis showed extensive synteny and identified 3068 coding regions which are conserved, at the same chromosomal position, in all A. baumannii genomes. Genome alignments also identified 63 DNA regions, ranging in size from 4 o 126 kb, all defined as genomic islands, which were present in some genomes, but were either missing or replaced by non-homologous DNA sequences in others. Some islands are involved in resistance to drugs and metals, others carry genes encoding surface proteins or enzymes involved in specific metabolic pathways, and others correspond to prophage-like elements. Accessory DNA regions encode 12 to 19% of the potential gene products of the analyzed strains. The analysis of a collection of epidemic A. baumannii strains showed that some islands were restricted to specific genotypes. The definition of the genome components of A. baumannii provides a scaffold to rapidly evaluate the genomic organization of novel clinical A. baumannii isolates. Changes in island profiling will be useful in genomic epidemiology of A. baumannii population.
-
Cui, Zhisong; Luan, Xiao; Jiang, Huichao; Li, Qian; Xu, Guangfei; Sun, Chengjun; Zheng, Li; Song, Yizhi; Davison, Paul A; Huang, Wei E
2018-06-01
A toxicity biosensor Acinetobacter baylyi Tox2 was constructed with the host strain A. baylyi ADP1 harboring a new and medium-copy-number plasmid pWH1274_lux, and was applied to detect the cytotoxicity of heavy metal contaminated seawater. The gene cassette luxCDABE was controlled by constitutively expressed promoter P tet on pWH1274_lux and the bioluminescence intensity of the biosensor reduces in proportional to the concentrations of toxic compounds. A. baylyi Tox2 exhibits tolerance to salinity, hence it is applicable to seawater samples. A. baylyi Tox2 and Mugilogobius chulae were exposed to different concentrations of heavy metals (Hg 2+ , Zn 2+ , Cu 2+ , and Cd 2+ ) in artificial seawater for performance comparison and Pearson correlation analysis showed a significant correlation (p < 0.01) between A. baylyi Tox2 toxicity detection and the fish (M. chulae) exposure test. This suggests that the performance of A. baylyi Tox2 is comparable to the conventional fish toxicity test in terms of cytotoxicity detection of heavy metal contaminated seawater. Furthermore, A. baylyi Tox2 was used to evaluate cytotoxicity of field-collected seawater samples. The results indicate that there was a significant correlation between the luminescence inhibition ratio (IR) of A. baylyi Tox2 and heavy metal concentrations detected by ICP-MS in the samples. Two seawater samples, which contained a high concentration of total heavy metals, exhibited stronger cytotoxicity than the samples containing low concentrations of heavy metals. In conclusion, A. baylyi Tox2 can be used as an alternative tool to aquatic animals for the evaluation of the cytotoxicity of heavy metal contamination in the marine environment. Copyright © 2018 Elsevier Ltd. All rights reserved.
-
Hosoyama, Akira; Yamazoe, Atsushi; Morikawa, Masaaki
2015-01-01
Acinetobacter calcoaceticus strain P23 is a plant growth-promoting bacterium, which was isolated from the surface of duckweed. We report here the draft genome sequence of strain P23. The genome data will serve as a valuable reference for understanding the molecular mechanism of plant growth promotion in aquatic plants. PMID:25720680
-
Acinetobacter kookii sp. nov., isolated from soil.
Choi, Ji Young; Ko, Gwangpyo; Jheong, Weonghwa; Huys, Geert; Seifert, Harald; Dijkshoorn, Lenie; Ko, Kwan Soo
2013-12-01
Two Gram-stain-negative, non-fermentative bacterial strains, designated 11-0202(T) and 11-0607, were isolated from soil in South Korea, and four others, LUH 13522, LUH 8638, LUH 10268 and LUH 10288, were isolated from a beet field in Germany, soil in the Netherlands, and sediment of integrated fish farms in Malaysia and Thailand, respectively. Based on 16S rRNA, rpoB and gyrB gene sequences, they are considered to represent a novel species of the genus Acinetobacter. Their 16S rRNA gene sequences showed greatest pairwise similarity to Acinetobacter beijerinckii NIPH 838(T) (97.9-98.4 %). They shared highest rpoB and gyrB gene sequence similarity with Acinetobacter johnsonii DSM 6963(T) and Acinetobacter bouvetii 4B02(T) (85.4-87.6 and 78.1-82.7 %, respectively). Strain 11-0202(T) displayed low DNA-DNA reassociation values (<40 %) with the most closely related species of the genus Acinetobacter. The six strains utilized azelate, 2,3-butanediol, ethanol and dl-lactate as sole carbon sources. Cellular fatty acid analyses showed similarities to profiles of related species of the genus Acinetobacter: summed feature 3 (C16 : 1ω7c, C16 : 1ω6c; 24.3-27.2 %), C18 : 1ω9c (19.9-22.1 %), C16 : 0 (15.2-22.0 %) and C12 : 0 (9.2-14.2 %). On the basis of the current findings, it is concluded that the six strains represent a novel species, for which the name Acinetobacter kookii sp. nov. is proposed. The type strain is 11-0202(T) ( = KCTC 32033(T) = JCM 18512(T)).
-
Krahn, Thomas; Wibberg, Daniel; Maus, Irena; Winkler, Anika; Pühler, Alfred; Poirel, Laurent; Schlüter, Andreas
2015-07-30
The complete genome sequence for the reference strain Acinetobacter baumannii CIP 70.10 (ATCC 15151) was established. The strain was isolated in France in 1970, is susceptible to most antimicrobial compounds, and is therefore of importance for comparative genome analyses with clinical multidrug-resistant (MDR) A. baumannii strains to study resistance development and acquisition in this emerging human pathogen. Copyright © 2015 Krahn et al.
-
Pérez-Oseguera, Ángeles; Castro-Jaimes, Semiramis; Salgado-Camargo, Abraham David; Silva-Sanchez, Jesus; Garza-González, Elvira; Castillo-Ramírez, Santiago
2017-01-01
ABSTRACT In this study, we present the complete genome sequence of a blaOXA-58-producing Acinetobacter baumannii strain, sampled from a Mexican hospital and not related to the international clones. PMID:28883144
-
Acinetobacter baumannii producing OXA-23 detected in the Czech Republic.
Senkyrikova, Marketa; Husickova, Vendula; Chroma, Magdalena; Sauer, Pavel; Bardon, Jan; Kolar, Milan
2013-12-01
Acinetobacter baumannii is an opportunistic pathogen posing an increased risk to hospitalized persons, causing nosocomial pneumonias, urinary tract infections and postoperative infections. Between 1 December 2011 and 30 September 2012, strains of Acinetobacter spp. were isolated from clinical samples obtained from hospitalized patients. Susceptibility to antibiotics was determined by the standard microdilution method and phenotypic testing was used to detect the presence of serine carbapenemases and metallo-beta-lactamases. The polymerase chain reaction was used to detect the genes encoding carbapenemases. Pulsed field gel electrophoresis was used to investigate the genetic relationship among the carbapenem resistant isolates of Acinetobacter baumannii. In three strains of Acinetobacter baumannii enzyme OXA-23 was detected. This positive result was confirmed by restriction analysis and sequencing. The study reported an OXA-23-producing strains of Acinetobacter baumannii in the Czech Republic. All three strains isolated from Military Hospital patients had a completely identical restriction profile, indicating clonal spread of a strain carrying serine carbapenemase OXA-23 in this health care facility. Moreover this was the first time the strain was detected in the country in patients who had not stayed abroad.
-
Malhotra, Jaya; Dua, Ankita; Saxena, Anjali; Sangwan, Naseer; Mukherjee, Udita; Pandey, Neeti; Rajagopal, Raman; Khurana, Paramjit; Khurana, Jitendra P.
2012-01-01
In this study, Acinetobacter sp. strain HA was isolated from the midgut of a fifth-instar larva of Helicoverpa armigera. Here, we report the draft genome sequence (3,125,085 bp) of this strain that consists of 102 contigs, 2,911 predicted coding sequences, and a G+C content of 41%. PMID:22933775
-
Liu, Hui; Lu, Qian; Wang, Qin; Liu, Wen; Wei, Qian; Ren, Hongyan; Ming, Caibing; Min, Min; Chen, Paul; Ruan, Roger
2017-07-01
Algae were able to grow healthy on bacteria-containing centrate wastewater in a pilot-scale bioreactor. The batch experiment indicated that the co-cultivation of algae and wastewater-borne bacteria improved the removal efficiencies of chemical oxygen demand and total phosphorus in centrate wastewater to 93.01% and 98.78%, respectively. A strain of beneficial aerobic bacteria, Acinetobacter sp., was isolated and its biochemical characteristics were explored. Synergistic cooperation was observed in the growth of algae and Acinetobacter sp. Removal efficiencies of some nutrients were improved significantly by the co-cultivation of algae and Acinetobacter sp. After treatment, residual nutrients in centrate wastewater reached the permissible discharge limit. The cooperation between algae and Acinetobacter sp. was in part attributed to the exchange of carbon dioxide and oxygen between the algae and bacteria. This synergetic relationship between algae and Acinetobacter sp. provided a promising way to treat the wastewater by improving the nutrients removal and biomass production. Copyright © 2017 Elsevier Ltd. All rights reserved.
-
Acinetobacter lactucae sp. nov., isolated from iceberg lettuce (Asteraceae: Lactuca sativa).
Rooney, Alejandro P; Dunlap, Christopher A; Flor-Weiler, Lina B
2016-09-01
Strain NRRL B-41902T and three closely related strains were isolated from iceberg lettuce. The strain was found to consist of strictly aerobic, Gram-stain-negative rods that formed cocci in late stationary phase. 16S rRNA gene sequence analysis showed that strain NRRL B-41902T was most closely related to species within the genera Acinetobacter, and that a grouping of it and the three other closely related strains was most closely related to the type strain of Acinetobacter pittii, which was also confirmed through a phylogenomic analysis. Moreover, in silico DNA-DNA hybridization analysis revealed a substantial amount of genomic divergence (39.1 %) between strain NRRL B-41902T and the type strain of A. pittii, which is expected if the strains represent distinct species. Further phenotypic analysis revealed that strain NRRL B-41902T was able to utilize a combination of l-serine, citraconic acid and citramalic acid, which differentiated it from other, closely related Acinetobacter species. Therefore, strain NRRL B-41902T (=CCUG 68785T) is proposed as the type strain of a novel species, Acinetobacter lactucae sp. nov.
-
Chen, Xiaoxin; He, Sheng; Liu, Xiaolu; Hu, Jiye
2018-09-15
Using sequential soil and liquid culture enrichments with cyprodinil as the sole carbon source, a Gram-negative cyprodinil-degrader from cyprodinil-polluted agricultural soil was isolated. The sequencing analysis of 16 S rRNA indicated that the strain showed 99% homology to Acinetobacter sp. The strain could effectively degrade cyprodinil at the neutral condition. At the initial concentrations of 10, 20, 50, 100, 150 and 200 mg L -1 in minimal medium, cyprodinil was degraded by 10, 20, 49.3, 64.2, 57 and 24 mg L -1 within 14 days, respectively. Two metabolites (4-cyclopropyl-6-methyl-2-pyrimidpyridine amine and monohydroxylated para-substitution) were identified using high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS/MS). A biodegradation pathway involving imines hydrolysis and monohydroxyl substitution on benzene ring was proposed on basis of the identified metabolites. Acinetobacter sp. would have a potential application in bioremediation of cyprodinil-contaminated soil, and the strain might have important implications in detoxification and bioremediation of pyrimidine analogues. Copyright © 2018 Elsevier Inc. All rights reserved.
-
Albarracín, Virginia Helena; Pathak, Gopal P; Douki, Thierry; Cadet, Jean; Borsarelli, Claudio Darío; Gärtner, Wolfgang; Farias, María Eugenia
2012-06-01
High-Altitude Andean Lakes (HAAL) of the South American Andes are almost unexplored ecosystems of shallow lakes. The HAAL are recognized by a remarkably high UV exposure, strong changes in temperature and salinity, and a high content of toxic elements, especially arsenic. Being exposed to remarkably extreme conditions, they have been classified as model systems for the study of life on other planets. Particularly, Acinetobacter strains isolated from the HAAL were studied for their survival competence under strong UV-B irradiation. Clinical isolates, Acinetobacter baumannii and Acinetobacter johnsonii, served as reference material. Whereas the reference strains rapidly lost viability under UV-B irradiation, most HAAL-derived strains readily survived this exposure and showed less change in cell number after the treatment. Controls for DNA repair activity, comparing dark repair (DR) or photo repair (PR), gave evidence for the involvement of photolyases in the DNA repair. Comparative measurements by HPLC-mass spectrometry detected the number of photoproducts: bipyrimidine dimers under both PR and DR treatments were more efficiently repaired in the HAAL strains (up to 85 % PR and 38 % DR) than in the controls (31 % PR and zero DR ability). Analysis of cosmid-cloned total genomic DNA from the most effective DNA-photorepair strain (Ver3) yielded a gene (HQ443199) encoding a protein with clear photolyase signatures belonging to class I CPD-photolyases. Despite the relatively low sequence similarity of 41 % between the enzymes from Ver3 and from E. coli (PDB 1DNPA), a model-building approach revealed a high structural homology to the CPD-photolyase of E. coli.
-
Enzymic Dehalogenation of 4-Chlorobenzoyl Coenzyme A in Acinetobacter sp. Strain 4-CB1
Copley, Shelley D.; Crooks, Gwen P.
1992-01-01
4-Chlorobenzoate degradation in cell extracts of Acinetobacter sp. strain 4-CB1 occurs by initial synthesis of 4-chlorobenzoyl coenzyme A (4-chlorobenzoyl CoA) from 4-chlorobenzoate, CoA, and ATP. 4-Chlorobenzoyl CoA is dehalogenated to 4-hydroxybenzoyl CoA. Following the dehalogenation reaction, 4-hydroxybenzoyl CoA is hydrolyzed to 4-hydroxybenzoate and CoA. Possible roles for the CoA moiety in the dehalogenation reaction are discussed. PMID:16348702
-
Baniya, Bandana; Pant, Narayan Dutt; Neupane, Sanjeev; Khatiwada, Saroj; Yadav, Uday Narayan; Bhandari, Nisha; Khadka, Rama; Bhatta, Sabita; Chaudhary, Raina
2017-11-02
Pseudomonas aeruginosa and Acinetobacter spp. are found to be associated with biofilm and metallo-β-lactamase production and are the common causes of serious infections mainly in hospitalized patients. So, the main aims of this study were to determine the rates of biofilm production and metallo beta-lactamase production (MBL) among the strains of Pseudomonas aeruginosa and Acinetobacter spp. isolated from hospitalized patients. A total of 85 P. aeruginosa isolates and 50 Acinetobacter spp. isolates isolated from different clinical specimens from patients admitted to Shree Birendra Hospital, Kathmandu, Nepal from July 2013 to May 2014 were included in this study. The bacterial isolates were identified with the help of biochemical tests. Modified Kirby-Bauer disc diffusion technique was used for antimicrobial susceptibility testing. Combined disc diffusion technique was used for the detection of MBL production, while Congo red agar method and tube adherence method were used for detection of biofilm production. Around 16.4% of P. aeruginosa isolates and 22% of the strains of Acinetobacter spp. were metallo β-lactamase producers. Out of 85 P. aeruginosa isolates, 23 (27.05%) were biofilm producers according to tube adherence test while, only 13 (15.29%) were biofilm producers as per Congo red agar method. Similarly, out of 50 Acinetobacter spp. 7 (14%) isolates were biofilm producers on the basis of tube adherence test, while only 5 (10%) were positive for biofilm production by Congo red agar method. Highest rates of susceptibility of P. aeruginosa as well as Acinetobacter spp. were seen toward colistin. In our study, biofilm production and metallo beta-lactamase production were observed among Pseudomonas aeruginosa and Acinetobacter spp. However, no statistically significant association could be established between biofilm production and metallo beta-lactamase production.
-
Jawad, A; Heritage, J; Snelling, A M; Gascoyne-Binzi, D M; Hawkey, P M
1996-01-01
Acinetobacter spp. are being reported with increasing frequency as a cause of nosocomial infection and have been isolated from the skin of healthy individuals, patients, hospital staff, dry nonbiotic objects, and different pieces of medical equipment. Factors affecting the survival of Acinetobacter spp. under conditions closely similar to those found in the hospital environment were investigated in the present study to help us understand the epidemiology of nosocomial Acinetobacter infection. Bacterial cells were suspended in distilled water or bovine serum albumin and were dried onto glass coverslips and kept at different relative humidities. Cells washed from coverslips were used to determined viable counts. Freshly isolated strains of Acinetobacter spp. belonging to the clinically important Acinetobacter calcoaceticus-Acinetobacter baumannii complex were found to be more resistant to drying conditions (e.g., 30 days for A. baumannii 16/49) than American Type Culture Collection strains (e.g., 2 days for A. baumannii ATCC 9955). The majority of strains belonging to the Acb complex had survival times similar to those observed for the gram-positive organism Staphylococcus aureus tested in the experiment. Survival times were prolonged for almost all the strains tested when they were suspended in bovine serum albumin (e.g., 60 days for A. baumannii R 447) compared with those for strains suspended in distilled water (11 days for R 447). The survival times for strains at higher relative humidity (31 or 93%) were longer than those for strains of Acinetobacter kept at a relative humidity of 10% (11 days at 31% relative humidity and 4 days at 10% relative humidity for R447). These findings are consistent with the observed tendency of Acinetobacter spp. to survive on dry surfaces, and they can be transferred not only by moist vectors but also under dry conditions in a hospital environment during nosocomial infection outbreaks. The results obtained in the experiment support
-
Characteristics of invasive Acinetobacter species isolates recovered in a pediatric academic center.
Jain, Avish L; Harding, Christian M; Assani, Kaivon; Shrestha, Chandra L; Haga, Mercedees; Leber, Amy; Munson, Robert S; Kopp, Benjamin T
2016-07-22
Acinetobacter species are associated with increasing mortality due to emerging drug-resistance. Pediatric Acinetobacter infections are largely undefined in developed countries and clinical laboratory identification methods do not reliably differentiate between members of the Acinetobacter calcoaceticus-baumannii complex, leading to improper identification. Therefore we aimed to determine risk factors for invasive Acinetobacter infections within an academic, pediatric setting as well as defining microbiologic characteristics of predominant strains. Twenty-four invasive Acinetobacter isolates were collected from 2009-2013. Comparative sequence analysis of the rpoB gene was performed coupled with phenotypic characterization of antibiotic resistance, motility, biofilm production and clinical correlation. Affected patients had a median age of 3.5 years, and 71 % had a central catheter infection source. rpoB gene sequencing revealed a predominance of A. pittii (45.8 %) and A. baumannii (33.3 %) strains. There was increasing incidence of A. pittii over the study. Two fatalities occurred in the A. pittii group. Seventeen percent of isolates were multi-drug resistant. A pittii and A. baumannii strains were similar in motility, but A pittii strains had significantly more biofilm production (P value = 0.018). A. pittii was the most isolated species highlighting the need for proper species identification. The isolated strains had limited acute mortality in children, but the occurrence of more multi-drug resistant strains in the future is a distinct possibility, justifying continued research and accurate species identification.
-
Kong, B H; Hanifah, Y A; Yusof, M Y; Thong, K L
2011-12-01
Acinetobacter baumannii, genomic species 3 and 13TU are being increasingly reported as the most important Acinetobacter species that cause infections in hospitalized patients. These Acinetobacter species are grouped in the Acinetobacter calcoaceticus- Acinetobacter baumannii (Acb) complex. Differentiation of the species in the Acb-complex is limited by phenotypic methods. Therefore, in this study, amplified ribosomal DNA restriction analysis (ARDRA) was applied to confirm the identity A. baumannii strains as well as to differentiate between the subspecies. One hundred and eighty-five strains from Intensive Care Unit, Universiti Malaya Medical Center (UMMC) were successfully identified as A. baumannii by ARDRA. Acinetobacter genomic species 13TU and 15TU were identified in 3 and 1 strains, respectively. ARDRA provides an accurate, rapid and definitive approach towards the identification of the species level in the genus Acinetobacter. This paper reports the first application ARDRA in genospecies identification of Acinetobacter in Malaysia.
-
Uniyal, Shivani; Paliwal, Rashmi; Verma, Megha; Sharma, R K; Rai, J P N
2016-06-01
An enrichment culture technique was used for the isolation of bacteria capable of utilizing fipronil as a sole source of carbon and energy. Based on morphological, biochemical characteristics and phylogenetic analysis of 16S rRNA sequence, the bacterial strains were identified as Acinetobacter calcoaceticus and Acinetobacter oleivorans. Biodegradation experiments were conducted in loamy sand soil samples fortified with fipronil (50 µg kg(-1)) and inoculated with Acinetobacter sp. cells (45 × 10(7) CFU mL(-1)) for 90 days. Soil samples were periodically analyzed by gas liquid chromatography equipped with electron capture detector. Biodegradation of fipronil fitted well with the pseudo first-order kinetics, with rate constant value between 0.041 and 0.051 days(-1). In pot experiments, fipronil and its metabolites fipronil sulfide, fipronil sulfone and fipronil amide were found below quantifiable limit in soil and root, shoot and leaves of Zea mays. These results demonstrated that A. calcoaceticus and A. oleivorans may serve as promising strains in the bioremediation of fipronil-contaminated soils.
-
Zeidler, Sabine; Hubloher, Josephine; Schabacker, Kim; Lamosa, Pedro; Santos, Helena; Müller, Volker
2017-12-01
Acinetobacter baumannii is an opportunistic human pathogen that has become a global threat to healthcare institutions worldwide. A major factor contributing to success of this bacterium is its outstanding ability to survive on dry surfaces. The molecular basis for desiccation resistance is not completely understood. This study focused on growth under osmotic stress and aimed to identify the pool of compatible solutes synthesized in response to these low water activity conditions. A. baumannii produced mannitol as compatible solute, but in contrast to Acinetobacter baylyi, also trehalose was accumulated in response to increasing NaCl concentrations. The genome of A. baumannii encodes a trehalose-6-phosphate phosphatase (OtsB) and a trehalose-6-phosphate synthase (OtsA). Deletion of otsB abolished trehalose formation, demonstrating that otsB is essential for trehalose biosynthesis. Growth of the mutant was neither impaired at low salt nor at 500 mM NaCl, but it did not grow at high temperatures, indicating a dual function of trehalose in osmo- and thermoprotection. This led us to analyse temperature dependence of trehalose formation. Indeed, expression of otsB was not only induced by high osmolarity but also by high temperature. Concurrently, trehalose was accumulated in cells grown at high temperature. Taken together, these data point to an important role of trehalose in A. baumannii beyond osmoprotection. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.
-
How, Kah Yan; Hong, Kar-Wai; Sam, Choon-Kook; Koh, Chong-Lek; Yin, Wai-Fong; Chan, Kok-Gan
2015-01-01
Myriad proteobacteria use N-acyl homoserine lactone (AHL) molecules as quorum sensing (QS) signals to regulate different physiological functions, including virulence, antibiotic production, and biofilm formation. Many of these proteobacteria possess LuxI/LuxR system as the QS mechanism. Recently, we reported the 3.89 Mb genome of Acinetobacter sp. strain GG2. In this work, the genome of this long chain AHL-producing bacterium was unravelled which led to the molecular characterization of luxI homologue, designated as aciI. This 552 bp gene was cloned and overexpressed in Escherichia coli BL21(DE3). The purified protein was ∼20.5 kDa and is highly similar to several autoinducer proteins of LuxI family among Acinetobacter species. To verify the AHL synthesis activity of this protein, high-resolution liquid chromatography–mass spectrometry analysis revealed the production of 3-oxo-dodecanoyl-homoserine lactone and 3-hydroxy-dodecanoyl-homoserine lactone from induced E. coli harboring the recombinant AciI. Our data show for the first time, the cloning and characterization of the luxI homologue from Acinetobacter sp. strain GG2, and confirmation of its AHLs production. These data are of great significance as the annotated genome of strain GG2 has provided a valuable insight in the study of autoinducer molecules and its roles in QS mechanism of the bacterium. PMID:25926817
-
Proliferation of spacecraft-associated Acinetobacter on alcohol solvents
NASA Astrophysics Data System (ADS)
Mogul, Rakesh; Cepeda, Ivonne; Brasali, Hania; Gornick, Trevor; Jain, Chirag; Kim, Eun Jin; Nguyen, Vinh Bao; Oei, Alex; Rodriguez, Joseph; Walker, Jillian; Savla, Gautam
The Acinetobacter are the most abundant Gram-negative and non-spore forming bacteria found in the cleanroom facilities for Mars spacecraft. The spacecraft-associated Acinetobacter are extremotolerant towards hydrogen peroxide and have been shown to increase in abundance as a result of the spacecraft assembly process. To better understand the oligotrophic growth in the cleanroom environments, we have measured the growth of several Acinetobacter strains against ethanol and isopropanol, which are cleaning solvents used in the spacecraft assembly process. Our studies show that A. radioresistens 50v1, which was isolated from Mars Odyssey orbiter, optimally proliferates on 300 mM ethanol under minimal conditions at a growth rate that is 2-fold higher than that of the A. radioresistens type strain (strain 43998 (T) ). The impact of transition metals on the growth rates followed the trend of Fe (2+) > Mn (2+) > Zn (2+) , where Zn (2+) was inhibitory. In contrast, no growth on ethanol was observed for the novel species A. phoenicis 2P01AA, which was isolated from the facilities for the Mars Phoenix lander. Alcohol dehydrogenase activities measured in rich and minimal media paralleled these observations with the 50v1 strain possessing higher specific activities than the type strain, and the 2P01AA strain displaying no measurable activity in rich media. Preliminary studies indicate that isopropanol is insufficient as an energy source when in culture. The significance of these results as well as the observed differences between the Odyssey and Phoenix-associated strains will be discussed.
-
Nasser, Kother; Mustafa, Abu Salim; Khan, Mohd Wasif; Purohit, Prashant; Al-Obaid, Inaam; Dhar, Rita; Al-Fouzan, Wadha
2018-04-19
Acinetobacter baumannii is an important opportunistic pathogen in global health care settings. Its dissemination and multidrug resistance pose an issue with treatment and outbreak control. Here, we present draft genome assemblies of six multidrug-resistant clinical strains of A. baumannii isolated from patients admitted to one of two major hospitals in Kuwait. Copyright © 2018 Nasser et al.
-
Šedo, Ondrej; Nemec, Alexandr; Křížová, Lenka; Kačalová, Magdaléna; Zdráhal, Zbyněk
2013-12-01
MALDI-TOF MS is currently becoming the method of choice for rapid identification of bacterial species in routine diagnostics. Yet, this method suffers from the inability to differentiate reliably between some closely related bacterial species including those of the Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex, namely A. baumannii and Acinetobacter nosocomialis. In the present study, we evaluated a protocol which was different from that used in the Bruker Daltonics identification system (MALDI BioTyper) to improve species identification using a taxonomically precisely defined set of 105 strains representing the four validly named species of the ACB complex. The novel protocol is based on the change in matrix composition from alpha-cyano-4-hydroxycinnamic acid (saturated solution in water:acetonitrile:trifluoroacetic acid, 47.5:50:2.5, v/v) to ferulic acid (12.5mgml(-1) solution in water:acetonitrile:formic acid 50:33:17, v/v), while the other steps of sample processing remain unchanged. Compared to the standard protocol, the novel one extended the range of detected compounds towards higher molecular weight, produced signals with better mass resolution, and allowed the detection of species-specific signals. As a result, differentiation of A. nosocomialis and A. baumannii strains by cluster analysis was improved and 13 A. nosocomialis strains, assigned erroneously or ambiguously by using the standard protocol, were correctly identified. Copyright © 2013 Elsevier GmbH. All rights reserved.
-
Panda, Jigisha; Sarkar, Priyabrata
2012-06-01
This study had an objective to identify the most potent chromium-resistant bacteria isolated from tannery effluent and apply them for bioremediation of chromium in tannery effluents. Two such strains (previously characterized and identified by us)--Enterobacter aerogenes (NCBI GenBank USA Accession no. GU265554) and Acinetobacter sp. PD 12 (NCBI GenBank USA Accession no. GU084179)--showed powerful chromium resistivity and bioremediation capabilities among many stains isolated from tannery waste. Parameters such as pH, concentration of hexavalent chromium or Cr (VI), and inoculum volume were varied to observe optimum bioconversion and bioaccumulation of Cr (VI) when the said strains were grown in M9 minimal salt media. E. aerogenes was used to remediate chromium from tannery effluents in a laboratory level experiment. Observation by Scanning Electron Microscope and chromium peak in Energy Dispersive X-ray Spectroscopic microanalysis revealed that E. aerogenes helped remediate a moderate amount of Cr (VI) (8-16 mg L(-1)) over a wide range of pH values at 35-37°C (within 26.05 h). High inoculum percentage of Acinetobacter sp. PD 12 also enabled bioremediation of 8-16 mg L(-1) of Cr (VI) over a wide range of temperature (25-37°C), mainly at pH 7 (within 63.28 h). The experiment with real tannery effluent gave very encouraging results. The strain E. aerogenes can be used in bioremediation of Cr (VI) since it could work in actual environmental conditions with extraordinarily high capacity.
-
Li, Hong; Ai, Hainan; Kang, Li; Sun, Xingfu; He, Qiang
2016-11-01
Measures for removal of toxic harmful algal blooms often cause lysis of algal cells and release of microcystins (MCs). In this study, Acinetobacter sp. CMDB-2 that exhibits distinct algal lysing activity and MCs degradation capability was isolated. The physiological response and morphological characteristics of toxin-producing Microcystis aeruginosa, the dynamics of intra- and extracellular MC-LR concentration were studied in an algal/bacterial cocultured system. The results demonstrated that Acinetobacter sp. CMDB-2 caused thorough decomposition of algal cells and impairment of photosynthesis within 24 h. Enhanced algal lysis and MC-LR release appeared with increasing bacterial density from 1 × 10 3 to 1 × 10 7 cells/mL; however, the MC-LR was reduced by nearly 94% within 14 h irrespective of bacterial density. Measurement of extracellular and intracellular MC-LR revealed that the toxin was decreased by 92% in bacterial cell incubated systems relative to control and bacterial cell-free filtrate systems. The results confirmed that the bacterial metabolite caused 92% lysis of Microcystis aeruginosa cells, whereas the bacterial cells were responsible for approximately 91% reduction of MC-LR. The joint efforts of the bacterium and its metabolite accomplished the sustainable removal of algae and MC-LR. This is the first report of a single bacterial strain that achieves these dual actions.
-
Experimental infection of human body lice with Acinetobacter baumannii.
Houhamdi, Linda; Raoult, Didier
2006-04-01
The human body louse is currently recognized as a vector of Rickettsia prowazekii, Borrelia recurrentis, and Bartonella quintana. Previous studies have reported the isolation of Acinetobacter baumannii from the body lice of homeless patients. To study how the body louse acquires A. baumannii, we infected a rabbit by infusing 2 x 10(6) colony-forming units of the louse strain of A. baumannii. Two hundred body lice were infected by feeding on the bacteremic rabbit and compared with 200 uninfected lice and two groups of 200 lice feeding on rabbits infected either with another strain of A. baumannii or A. lwoffii. Each louse group received maintenance feedings once a day on another seronegative rabbit. Body lice that fed on rabbits infused with each Acinetobacter species demonstrated a generalized infection. The body lice did not transmit their infection to the nurse rabbit by bite while feeding or to their progeny (eggs and larvae). The lice excreted living Acinetobacter species within their feces. Only the louse strain of A. baumannii was pathogenic for the body louse. An increased mortality rate was observed between the second and third days post-infection; however, they remained infected for their lifespan.
-
Lin, Johnson; Sharma, Vikas; Milase, Ridwaan; Mbhense, Ntuthuko
2016-06-01
Phenol degradation enhancement of Acinetobacter strain V2 by a step-wise continuous acclimation process was investigated. At the end of 8 months, three stable adapted strains, designated as R, G, and Y, were developed with the sub-lethal concentration of phenol at 800, 1100, and 1400 mg/L, respectively, from 400 mg/L of V2 parent strain. All strains degraded phenol at their sub-lethal level within 24 h, their growth rate increased as the acclimation process continued and retained their degradation properties even after storing at -80 °C for more than 3 years. All adapted strains appeared coccoid with an ungranulated surface under electron microscope compared to typical rod-shaped parental strain V2 . The adapted Y strain also possessed superior degradation ability against aniline, benzoate, and toluene. This study demonstrated the use of long term acclimation process to develop efficient and better pollutant degrading bacterial strains with potentials in industrial and environmental bioremediation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
-
Perilli, M; Felici, A; Oratore, A; Cornaglia, G; Bonfiglio, G; Rossolini, G M; Amicosante, G
1996-01-01
The beta-lactamases produced by Acinetobacter lwoffii ULA-501, Acinetobacter baumannii ULA-187, and A. baumannii AC-14 strains were purified and characterized, and their kinetic interactions with several beta-lactam molecules, including substrates and inhibitors, were studied in detail. The three enzymes appeared to be cephalosporinases with different acylation efficiencies (kcat/Km ratio values), and their hydrolytic activities were inhibited by benzylpenicillin, piperacillin, and cefotaxime, which did not behave as substrates. Carbenicillin was a substrate for the beta-lactamase from A. lwoffii ULA-501, whereas it acted as a transient inactivator of the enzymes produced by the two A. baumannii strains. Clavulanic acid was unable to inactivate the three beta-lactamases, whereas sulbactam behaved as an inactivator only at a high concentration (1 mM) which is difficult to achieve during antibiotic therapy. Analysis of the interaction with 6-beta-iodopenicillanic acid also allowed us to better discriminate the three beta-lactamases analyzed in the present study, which can be included in the group 1 functional class (5). PMID:8851599
-
Diversity within the O-linked protein glycosylation systems of acinetobacter species.
Scott, Nichollas E; Kinsella, Rachel L; Edwards, Alistair V G; Larsen, Martin R; Dutta, Sucharita; Saba, Julian; Foster, Leonard J; Feldman, Mario F
2014-09-01
The opportunistic human pathogen Acinetobacter baumannii is a concern to health care systems worldwide because of its persistence in clinical settings and the growing frequency of multiple drug resistant infections. To combat this threat, it is necessary to understand factors associated with disease and environmental persistence of A. baumannii. Recently, it was shown that a single biosynthetic pathway was responsible for the generation of capsule polysaccharide and O-linked protein glycosylation. Because of the requirement of these carbohydrates for virulence and the non-template driven nature of glycan biogenesis we investigated the composition, diversity, and properties of the Acinetobacter glycoproteome. Utilizing global and targeted mass spectrometry methods, we examined 15 strains and found extensive glycan diversity in the O-linked glycoproteome of Acinetobacter. Comparison of the 26 glycoproteins identified revealed that different A. baumannii strains target similar protein substrates, both in characteristics of the sites of O-glycosylation and protein identity. Surprisingly, glycan micro-heterogeneity was also observed within nearly all isolates examined demonstrating glycan heterogeneity is a widespread phenomena in Acinetobacter O-linked glycosylation. By comparing the 11 main glycoforms and over 20 alternative glycoforms characterized within the 15 strains, trends within the glycan utilized for O-linked glycosylation could be observed. These trends reveal Acinetobacter O-linked glycosylation favors short (three to five residue) glycans with limited branching containing negatively charged sugars such as GlcNAc3NAcA4OAc or legionaminic/pseudaminic acid derivatives. These observations suggest that although highly diverse, the capsule/O-linked glycan biosynthetic pathways generate glycans with similar characteristics across all A. baumannii. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.
-
Fatty aldehyde dehydrogenases in Acinetobacter sp. strain HO1-N: role in hexadecanol metabolism.
Singer, M E; Finnerty, W R
1985-01-01
The role of fatty aldehyde dehydrogenases (FALDHs) in hexadecane and hexadecanol metabolism was studied in Acinetobacter sp. strain HO1-N. Two distinct FALDHs were demonstrated in Acinetobacter sp. strain HO1-N: a membrane-bound, NADP-dependent FALDH activity induced 5-, 15-, and 9-fold by growth on hexadecanol, dodecyl aldehyde, and hexadecane, respectively, and a constitutive, NAD-dependent, membrane-localized FALDH. The NADP-dependent FALDH exhibited apparent Km and Vmax values for decyl aldehyde of 5.0, 13.0, 18.0, and 18.3 microM and 537.0, 500.0, 25.0, and 38.0 nmol/min in hexadecane-, hexadecanol-, ethanol-, palmitate-grown cells, respectively. FALDH isozymes ald-a, ald-b, and ald-c were demonstrated by gel electrophoresis in extracts of hexadecane- and hexadecanol-grown cells. ald-a, ald-b, and ald-d were present in dodecyl aldehyde-grown cells, while palmitate-grown control cells contained ald-b and ald-d. Dodecyl aldehyde-negative mutants were isolated and grouped into two phenotypic classes based on growth: class 1 mutants were hexadecane and hexadecanol negative and class 2 mutants were hexadecane and hexadecanol positive. Specific activity of NADP-dependent FALDH in Ald21 (class 1 mutant) was 85% lower than that of wild-type FALDH, while the specific activity of Ald24 (class 2 mutant) was 55% greater than that of wild-type FALDH. Ald21R, a dodecyl aldehyde-positive revertant able to grow on hexadecane, hexadecanol, and dodecyl aldehyde, exhibited a 100% increase in the specific activity of the NADP-dependent FALDH. The oxidation of [3H]hexadecane byAld21 yielded the accumulation of 61% more fatty aldehyde than the wild type, while Ald24 accumulated 27% more fatty aldehyde, 95% more fatty alcohol, and 65% more wax ester than the wild type. This study provides genetic and physiological evidence for the role of fatty aldehyde as an essential metabolic intermediate and NADP-dependent FALDH as a key enzyme in the dissimilation of hexadecane, hexadecanol
-
Snelling, A M; Gerner-Smidt, P; Hawkey, P M; Heritage, J; Parnell, P; Porter, C; Bodenham, A R; Inglis, T
1996-01-01
Acinetobacter spp. are being reported with increasing frequency as causes of nosocomial infection. In order to identify reservoirs of infection as quickly as possible, a rapid typing method that can differentiate epidemic strains from environmental and nonepidemic strains is needed. In 1993, a cluster of Acinetobacter baumannii isolates from five patients in the adult intensive therapy unit of our tertiary-care teaching hospital led us to develop and optimize a rapid repetitive extragenic palindromic sequence-based PCR (REP-PCR) typing protocol for members of the Acinetobacter calcoaceticus-A. baumannii complex that uses boiled colonies and consensus primers aimed at repetitive extragenic palindromic sequences. Four of the five patient isolates gave the same REP-PCR typing pattern as isolates of A. baumannii obtained from the temperature probe of a Bennett humidifier; the fifth isolate had a unique profile. Disinfection of the probe with 70% ethanol, as recommended by the manufacturer, proved ineffective, as A. baumannii with the same REP-PCR pattern was isolated from it 10 days after cleaning, necessitating a change in our decontamination procedure. Results obtained with REP-PCR were subsequently confirmed by ribotyping. To evaluate the discriminatory power (D) of REP-PCR for typing members of the A. calcoaceticus-A. baumannii complex, compared with that of ribotyping, we have applied both methods to a collection of 85 strains that included representatives of six DNA groups within the complex. Ribotyping using EcoRI digests yielded 53 patterns (D = 0.98), whereas 68 different REP-PCR patterns were observed (D = 0.99). By computer-assisted analysis of gel images, 74 patterns were observed with REP-PCR (D = 1.0). Overall, REP-PCR typing proved to be slightly more discriminatory than ribotyping. Our results indicate that REP-PCR typing used boiled colonies is a simple, rapid, and effective means of typing members of the A. calcoaceticus-A. baumannii complex. PMID
-
Acinetobacter apis sp. nov., isolated from the intestinal tract of a honey bee, Apis mellifera.
Kim, Pil Soo; Shin, Na-Ri; Kim, Joon Yong; Yun, Ji-Hyun; Hyun, Dong-Wook; Bae, Jin-Woo
2014-08-01
A novel Gram-negative, obligate aerobic, non-motile, and both coccobacillus- and bacillus-shaped bacterium, designated strain HYN18(T), was isolated from the intestinal tract of a honey bee (Apis mellifera). The isolate was oxidase-negative and catalase-positive. Strain HYN18(T) showed optimum growth at 25°C, pH 6-7, and in the presence of 1% (w/v) NaCl in trypticase soy broth medium. The isolate was negative for hydrolyses of starch, casein, gelatin and urea, indole production from tryptone and hemolysis on sheep blood agar. A phylogenetic analysis based on the 16S rRNA gene and rpoB gene sequence showed that strain HYN18(T) was most closely related to Acinetobacter nectaris SAP 763.2(T) and A. boissieri SAP 284.1(T) with 98.3% and 98.1% similarity (16S rRNA gene), respectively, and 84.4% similarity with Acinetobacter nectaris SAP 763.2(T) (rpoB gene). The major cellular fatty acids were summed features 3 (comprising C16:1ω7c /C16:1ω6c ), C12:0 and C16:0. The main isoprenoid quinone was ubiquinone-9 (Q-9). The polar lipids of strain HYN18(T) were phosphatidylethanolamine, three unidentified lipids, an unidentified phospholipid and an unidentified glycolipid. The DNA G+C content was 40.6 mol%. DNA-DNA hybridization experiments indicated less than 33 ± 10% relatedness to the closest phylogenetic species, Acinetobacter nectaris SAP 763.2(T). Thus, the phenotypic, phylogenetic and genotypic analyses indicate that strain HYN18(T) is a novel species within the genus Acinetobacter, for which the name Acinetobacter apis is proposed. The type strain is HYN18(T) (=KACC 16906(T) =JCM 18575(T)).
-
Montaña, Sabrina; Schramm, Sareda T J; Traglia, German Matías; Chiem, Kevin; Parmeciano Di Noto, Gisela; Almuzara, Marisa; Barberis, Claudia; Vay, Carlos; Quiroga, Cecilia; Tolmasky, Marcelo E; Iriarte, Andrés; Ramírez, María Soledad
2016-01-01
Acinetobacter johnsonii rarely causes human infections. While most A. johnsonii isolates are susceptible to virtually all antibiotics, strains harboring a variety of β-lactamases have recently been described. An A. johnsonii Aj2199 clinical strain recovered from a hospital in Buenos Aires produces PER-2 and OXA-58. We decided to delve into its genome by obtaining the whole genome sequence of the Aj2199 strain. Genome comparison studies on Aj2199 revealed 240 unique genes and a close relation to strain WJ10621, isolated from the urine of a patient in China. Genomic analysis showed evidence of horizontal genetic transfer (HGT) events. Forty-five insertion sequences and two intact prophages were found in addition to several resistance determinants such as blaPER-2, blaOXA-58, blaTEM-1, strA, strB, ereA, sul1, aacC2 and a new variant of blaOXA-211, called blaOXA-498. In particular, blaPER-2 and blaTEM-1 are present within the typical contexts previously described in the Enterobacteriaceae family. These results suggest that A. johnsonii actively acquires exogenous DNA from other bacterial species and concomitantly becomes a reservoir of resistance genes.
-
Draft Genome Sequences of Acinetobacter baumannii Isolates from Wounded Military Personnel.
Arivett, Brock A; Ream, Dave C; Fiester, Steven E; Kidane, Destaalem; Actis, Luis A
2016-08-25
Acinetobacter baumannii is a Gram-negative bacterium capable of causing hospital-acquired infections that has been grouped with Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species as ESKAPE pathogens because of their extensive drug resistance phenotypes and increasing risk to human health. Twenty-four multidrug-resistant A. baumannii strains isolated from wounded military personnel were sequenced and annotated. Copyright © 2016 Arivett et al.
-
Acinetobacter baumannii in Human Body Louse
Raoult, Didier
2004-01-01
While we were isolating Bartonella quintana from body lice, 40 Acinetobacter baumannii strains were also isolated and genotyped. One clone was unique and the other was ampicillin susceptible. A. baumannii DNA was later detected in 21% of 622 lice collected worldwide. These findings show an A. baumannii epidemic in human body lice. PMID:15498175
-
Mindlin, Sofia; Petrenko, Anatolii; Kurakov, Anton; Beletsky, Alexey; Mardanov, Andrey; Petrova, Mayya
2016-01-01
We performed whole-genome sequencing of five permafrost strains of Acinetobacter lwoffii (frozen for 15-3000 thousand years) and analyzed their resistance genes found in plasmids and chromosomes. Four strains contained multiple plasmids (8-12), which varied significantly in size (from 4,135 to 287,630 bp) and genetic structure; the fifth strain contained only two plasmids. All large plasmids and some medium-size and small plasmids contained genes encoding resistance to various heavy metals, including mercury, cobalt, zinc, cadmium, copper, chromium, and arsenic compounds. Most resistance genes found in the ancient strains of A . lwoffii had their closely related counterparts in modern clinical A . lwoffii strains that were also located on plasmids. The vast majority of the chromosomal resistance determinants did not possess complete sets of the resistance genes or contained truncated genes. Comparative analysis of various A . lwoffii and of A . baumannii strains discovered a number of differences between them: (i) chromosome sizes in A . baumannii exceeded those in A . lwoffii by about 20%; (ii) on the contrary, the number of plasmids in A . lwoffii and their total size were much higher than those in A . baumannii ; (iii) heavy metal resistance genes in the environmental A . lwoffii strains surpassed those in A . baumannii strains in the number and diversity and were predominantly located on plasmids. Possible reasons for these differences are discussed.
-
Kurakov, Anton; Beletsky, Alexey; Mardanov, Andrey
2016-01-01
We performed whole-genome sequencing of five permafrost strains of Acinetobacter lwoffii (frozen for 15–3000 thousand years) and analyzed their resistance genes found in plasmids and chromosomes. Four strains contained multiple plasmids (8–12), which varied significantly in size (from 4,135 to 287,630 bp) and genetic structure; the fifth strain contained only two plasmids. All large plasmids and some medium-size and small plasmids contained genes encoding resistance to various heavy metals, including mercury, cobalt, zinc, cadmium, copper, chromium, and arsenic compounds. Most resistance genes found in the ancient strains of A. lwoffii had their closely related counterparts in modern clinical A. lwoffii strains that were also located on plasmids. The vast majority of the chromosomal resistance determinants did not possess complete sets of the resistance genes or contained truncated genes. Comparative analysis of various A. lwoffii and of A. baumannii strains discovered a number of differences between them: (i) chromosome sizes in A. baumannii exceeded those in A. lwoffii by about 20%; (ii) on the contrary, the number of plasmids in A. lwoffii and their total size were much higher than those in A. baumannii; (iii) heavy metal resistance genes in the environmental A. lwoffii strains surpassed those in A. baumannii strains in the number and diversity and were predominantly located on plasmids. Possible reasons for these differences are discussed. PMID:27795957
-
Gkorezis, Panagiotis; Rineau, Francois; Van Hamme, Jonathan; Franzetti, Andrea; Daghio, Matteo; Thijs, Sofie; Weyens, Nele; Vangronsveld, Jaco
2015-02-05
We report the 3.7-Mb draft genome of Acinetobacter oleivorans strain PF1, a hydrocarbonoclastic Gram-negative bacterium in the class Gammaproteobacteria, isolated from poplar trees growing on a diesel-contaminated plume at the Ford Motor Company site in Genk, Belgium. Strain PF1 is a potent plant-growth promoter, useful for diesel fuel phytoremediation applications. Copyright © 2015 Gkorezis et al.
-
Effect of multipurpose solutions against Acinetobacter carrying QAC genes.
Boost, Maureen V; Chan, Jessica; Shi, Guang-sen; Cho, Pauline
2014-03-01
Acinetobacter has low virulence but causes infections in subjects with reduced immunity. It has been reported in ocular infections including those of patients using contact lenses. Treatment is difficult because Acinetobacter is frequently multidrug resistant. Antibiotic-resistant strains frequently also harbor genes for antiseptic resistance (quaternary ammonium compound [QAC]) genes. Because Acinetobacter is part of the normal flora, it may contaminate contact lens and accessories. This study aims to investigate carriage rates of QAC genes in household and clinical isolates of Acinetobacter and to determine the effectiveness of two multipurpose solutions (MPSs) for soft lenses against organisms carrying QAC genes. DNA was extracted from 11 bathroom isolates and 15 clinical isolates and amplified by polymerase chain reaction to determine the presence of qacEΔ1. Gene-positive and gene-negative control strains were used to challenge the two MPSs, and minimum inhibitory concentrations (MICs) of these organisms to benzalkonium chloride and chlorhexidine gluconate were determined. More than 90% of isolates carried qacEΔ1. The MICs of clinical isolates were higher than those of isolates of bathrooms. Both MPSs were able to produce a 3-log reduction in the numbers of all isolates. Although most isolates carried qacEΔ1 and elevated MICs to benzalkonium chloride and chlorhexidine gluconate were observed, all were susceptible to both MPSs tested. However, if there were to be poor compliance with care procedures, it is probable that such organisms could survive in the presence of diluted or expired solutions.
-
Castillo, Andres; Chávez-Vivas, Mónica
2017-01-01
Abstract Introduction: The extensive use of antibiotics has led to the emergence of multi-resistant strains in some species of the genus Acinetobacter. Objective: To investigate the molecular characteristics of multidrug-resistant of Acinetobacter ssp. strains isolated from 52 patients collected between March 2009 and July 2010 in medical intensive care units in Cali - Colombia. Methods: The susceptibility to various classes of antibiotics was determined by disc diffusion method, and the determination of the genomic species was carried out using amplified ribosomal DNA restriction analysis (ARDRA) and by sequencing of the 16s rDNA gene. Also, the genes of beta-lactamases as well as, integrases IntI1 and IntI2 were analyzed by PCR method. Results: The phenotypic identification showed that the isolates belong mainly to A. calcoaceticus- A. baumannii complex. All of them were multi-resistant to almost the whole antibiotics except to tigecycline and sulperazon, and they were grouped into five (I to V) different antibiotypes, being the antibiotype I the most common (50.0%). The percent of beta-lactamases detected was: blaTEM (17.3%), blaCTX-M (9.6%), blaVIM (21.2%), blaIMP (7.7%), blaOXA-58 (21.2%), and blaOXA-51 (21.2%). The phylogenetic tree analysis showed that the isolates were clustering to A. baumannii (74.1%), A. nosocomialis (11.1%) and A. calcoaceticus (7.4 %). Besides, the integron class 1 and class 2 were detected in 23.1% and 17.3% respectively. Conclusion: The isolates were identified to species A. baumanii mainly, and they were multiresistant. The resistance to beta-lactams may be by for presence of beta-lactamases in the majority of the isolates. PMID:29662260
-
Nielsen, Kaare M.; van Elsas, Jan D.; Smalla, Kornelia
2000-01-01
Here we show that horizontal transfer of DNA, extracted from transgenic sugar beets, to bacteria, based on homologous recombination, can occur in soil. Restoration of a 317-bp-deleted nptII gene in Acinetobacter sp. strain BD413(pFG4) cells incubated in sterile soil microcosms was detected after addition of nutrients and transgenic plant DNA encoding a functional nptII gene conferring bacterial kanamycin resistance. Selective effects of the addition of kanamycin on the population dynamics of Acinetobacter sp. cells in soil were found, and high concentrations of kanamycin reduced the CFU of Acinetobacter sp. cells from 109 CFU/g of soil to below detection. In contrast to a chromosomal nptII-encoded kanamycin resistance, the pFG4-generated resistance was found to be unstable over a 31-day incubation period in vitro. PMID:10698801
-
Shahcheraghi, F; Abbasalipour, M; Feizabadi, MM; Ebrahimipour, GH; Akbari, N
2011-01-01
Background and Objective Carbapenems are therapeutic choice against infections caused by gram-negative bacilli including strains of Acinetobacter baumannii. Resistance to these antibiotics is mediated by efflux pumps, porins, PBPs and ß-lactamases. The aim of this study was to determine the possibility of existence of MBLs, OXAs and GES-1 betalactamase genes among clinical isolates of Acinetobacter collected from Tehran hospitals. Material and Methods Two hundred and three Acinetobacter isolates were collected from patient at Tehran hospitals. The isolates were identified using biochemical tests. The susceptibility to different antibiotics was evaluated by disk diffusion method and MICs of imipenem were determined using Micro broth dilution method (CLSI). PCR was performed for detection of bla VIM-2, bla SPM-1, bla IMP-2, bla GES-1, bla OXA-51, bla OXA-23 betalactamase genes. Clonal relatedness was estimated by PFGE with the restriction enzyme SmaI. Results and Conclusion Of 100 isolates of imipenem resistant Acinetobacter spp. collected from Tehran hospitals in 2009 and 2010, 6 isolates produced metallo-beta-lactamases and 94 isolates produced OXA-type carbapenemase. The bla SPM-1, bla GES-1, bla OXA-51, bla OXA-23 genes were detected by PCR among 6, 2, 94 and 84 isolates of A. baumannii, respectively. The MICs of isolates to imipenem were 8–128 µg/mL. PFGE analysis of 29 bla OXA-51 and bla OXA-23-positive A. baumannii isolates gave 6 different patterns. This is the first report of SPM-1 and GES-1 beta-lactamase producing A. baumannii. Production of the OXA-23, OXA-51, GES-1 and SPM-1 enzyme presents an emerging threat of carbapenem resistance among A. baumannii in Iran. PMID:22347585
-
Arivett, Brock A.; Fiester, Steven E.; Ohneck, Emily J.; Penwell, William F.; Kaufman, Cynthia M.; Relich, Ryan F.
2015-01-01
A paucity of effective, currently available antibiotics and a lull in antibiotic development pose significant challenges for treatment of patients with multidrug-resistant (MDR) Acinetobacter baumannii infections. Thus, novel therapeutic strategies must be evaluated to meet the demands of treatment of these often life-threatening infections. Accordingly, we examined the antibiotic activity of gallium protoporphyrin IX (Ga-PPIX) against a collection of A. baumannii strains, including nonmilitary and military strains and strains representing different clonal lineages and isolates classified as susceptible or MDR. Susceptibility testing demonstrated that Ga-PPIX inhibits the growth of all tested strains when cultured in cation-adjusted Mueller-Hinton broth, with a MIC of 20 μg/ml. This concentration significantly reduced bacterial viability, while 40 μg/ml killed all cells of the A. baumannii ATCC 19606T and ACICU MDR isolate after 24-h incubation. Recovery of ATCC 19606T and ACICU strains from infected A549 human alveolar epithelial monolayers was also decreased when the medium was supplemented with Ga-PPIX, particularly at a 40-μg/ml concentration. Similarly, the coinjection of bacteria with Ga-PPIX increased the survival of Galleria mellonella larvae infected with ATCC 19606T or ACICU. Ga-PPIX was cytotoxic only when monolayers or larvae were exposed to concentrations 16-fold and 1,250-fold higher than those showing antibacterial activity, respectively. These results indicate that Ga-PPIX could be a viable therapeutic option for treatment of recalcitrant A. baumannii infections regardless of the resistance phenotype, clone lineage, time and site of isolation of strains causing these infections and their iron uptake phenotypes or the iron content of the media. PMID:26416873
-
Susceptibility of Acinetobacter Strains Isolated from Deployed U.S. Military Personnel▿
Hawley, Joshua S.; Murray, Clinton K.; Griffith, Matthew E.; McElmeel, M. Leticia; Fulcher, Letitia C.; Hospenthal, Duane R.; Jorgensen, James H.
2007-01-01
The susceptibilities of 142 Acinetobacter baumannii-calcoaceticus complex isolates (95 from wounded U.S. soldiers deployed overseas) to 13 antimicrobial agents were determined by broth microdilution. The most active antimicrobial agents (≥95% of isolates susceptible) were colistin, polymyxin B, and minocycline. PMID:17043112
-
Arivett, Brock A; Fiester, Steven E; Ohneck, Emily J; Penwell, William F; Kaufman, Cynthia M; Relich, Ryan F; Actis, Luis A
2015-12-01
A paucity of effective, currently available antibiotics and a lull in antibiotic development pose significant challenges for treatment of patients with multidrug-resistant (MDR) Acinetobacter baumannii infections. Thus, novel therapeutic strategies must be evaluated to meet the demands of treatment of these often life-threatening infections. Accordingly, we examined the antibiotic activity of gallium protoporphyrin IX (Ga-PPIX) against a collection of A. baumannii strains, including nonmilitary and military strains and strains representing different clonal lineages and isolates classified as susceptible or MDR. Susceptibility testing demonstrated that Ga-PPIX inhibits the growth of all tested strains when cultured in cation-adjusted Mueller-Hinton broth, with a MIC of 20 μg/ml. This concentration significantly reduced bacterial viability, while 40 μg/ml killed all cells of the A. baumannii ATCC 19606(T) and ACICU MDR isolate after 24-h incubation. Recovery of ATCC 19606(T) and ACICU strains from infected A549 human alveolar epithelial monolayers was also decreased when the medium was supplemented with Ga-PPIX, particularly at a 40-μg/ml concentration. Similarly, the coinjection of bacteria with Ga-PPIX increased the survival of Galleria mellonella larvae infected with ATCC 19606(T) or ACICU. Ga-PPIX was cytotoxic only when monolayers or larvae were exposed to concentrations 16-fold and 1,250-fold higher than those showing antibacterial activity, respectively. These results indicate that Ga-PPIX could be a viable therapeutic option for treatment of recalcitrant A. baumannii infections regardless of the resistance phenotype, clone lineage, time and site of isolation of strains causing these infections and their iron uptake phenotypes or the iron content of the media. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
-
Krizova, Lenka; Dijkshoorn, Lenie; Nemec, Alexandr
2011-01-01
To assess the diversity of AbaR genomic resistance islands in Acinetobacter baumannii European clone I (MLST clonal complex 1), we investigated 26 multidrug-resistant strains of this major clone isolated from hospitals in 21 cities of 10 European countries between 1984 and 2005. Each strain harbored an AbaR structure integrated at the same position in the chromosomal ATPase gene. AbaR3, including four subtypes based on variations in class 1 integron cassettes, and AbaR10 were found in 15 and 2 strains, respectively, whereas a new, unique AbaR variant was discovered in each of the other 9 strains. These new variants, designated AbaR11 to AbaR19 (19.8 kb to 57.5 kb), seem to be truncated derivatives of AbaR3, likely resulting from the deletions of its internal parts mediated by either IS26 elements (AbaR12 to AbaR19) or homologous recombination (AbaR11). AbaR3 was detected in all 10 strains isolated in 1984 to 1991, while AbaR11 to AbaR19 were carried only by strains isolated since 1997. Our results and those from previous publications suggest that AbaR3 is the original form of AbaR in European clone I, which may have provided strains of the lineage with a selective advantage facilitating their spread in European hospitals in the 1980s or before. PMID:21537009
-
Jung, Jaejoon; Park, Woojun
2015-03-01
Acinetobacter occupies an important position in nature because of its ubiquitous presence in diverse environments such as soils, fresh water, oceans, sediments, and contaminated sites. Versatile metabolic characteristics allow species of this genus to catabolize a wide range of natural compounds, implying active participation in the nutrient cycle in the ecosystem. On the other hand, multi-drug-resistant Acinetobacter baumannii causing nosocomial infections with high mortality has been raising serious concerns in medicine. Due to the ecological and clinical importance of the genus, Acinetobacter was proposed as a model microorganism for environmental microbiological studies, pathogenicity tests, and industrial production of chemicals. For these reasons, Acinetobacter has attracted significant attention in scientific and biotechnological fields, but only limited research areas such as natural transformation and aromatic compound degradation have been intensively investigated, while important physiological characteristics including quorum sensing, motility, and stress response have been neglected. The aim of this review is to summarize the recent achievements in Acinetobacter research with a special focus on strain DR1 and to compare the similarities and differences between species or other genera. Research areas that require more attention in future research are also suggested.
-
Clinical and Pathophysiological Overview of Acinetobacter Infections: a Century of Challenges
Nielsen, Travis B.; Bonomo, Robert A.; Pantapalangkoor, Paul; Luna, Brian; Spellberg, Brad
2016-01-01
SUMMARY Acinetobacter is a complex genus, and historically, there has been confusion about the existence of multiple species. The species commonly cause nosocomial infections, predominantly aspiration pneumonia and catheter-associated bacteremia, but can also cause soft tissue and urinary tract infections. Community-acquired infections by Acinetobacter spp. are increasingly reported. Transmission of Acinetobacter and subsequent disease is facilitated by the organism's environmental tenacity, resistance to desiccation, and evasion of host immunity. The virulence properties demonstrated by Acinetobacter spp. primarily stem from evasion of rapid clearance by the innate immune system, effectively enabling high bacterial density that triggers lipopolysaccharide (LPS)–Toll-like receptor 4 (TLR4)-mediated sepsis. Capsular polysaccharide is a critical virulence factor that enables immune evasion, while LPS triggers septic shock. However, the primary driver of clinical outcome is antibiotic resistance. Administration of initially effective therapy is key to improving survival, reducing 30-day mortality threefold. Regrettably, due to the high frequency of this organism having an extreme drug resistance (XDR) phenotype, early initiation of effective therapy is a major clinical challenge. Given its high rate of antibiotic resistance and abysmal outcomes (up to 70% mortality rate from infections caused by XDR strains in some case series), new preventative and therapeutic options for Acinetobacter spp. are desperately needed. PMID:27974412
-
Prevalence of carbapenem-resistant Acinetobacter baumannii from 2005 to 2016 in Switzerland.
Ramette, A; Kronenberg, A
2018-04-03
We describe the prevalence of invasive carbapenem-resistant Acinetobacter spp. isolated from 2005 to 2016 in different regions of Switzerland. Using the Swiss Antibiotic Resistance Centre (anresis) database that includes data from 70% of all hospitalized patients and one third of all ambulatory practitioners in Switzerland, we analysed the number of carbapenem-susceptible and resistant Acinetobacter spp. isolated from blood or cerebrospinal fluid, and further described their temporal and regional fluctuations. From 2005 to 2016, 58 cases of resistant or intermediate strains to carbapenem were observed among 632 cases of invasive Acinetobacter. Multivariable analyses indicated that the number of carbapenem-resistant isolates (mean 4.8 ± sd 2.12) and carbapenem resistance rates per region per annum (8.4% ± 13.9%) were low and stable over the studied period. Large fluctuations were observed at the regional level, with e.g. the North East region displaying resistance rates twice as high as that found in other regions. Despite a relatively stable number of carbapenem-resistant Acinetobacter isolates in Switzerland, our results suggest the existence of a diverse pool of A. baumannii species in hospital settings, and confirm the implication of carbapenem-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex in the vast majority of clinical infections and nosocomial outbreaks with notable regional fluctuations.
-
George, Lijo; Hiltunen, Arto; Santala, Ville; Efimov, Alexander
2018-06-01
The properties and antimicrobial efficacies of zinc complexes of tetrakis(N-methylpyridinium-4-yl) tetraiodide porphyrin and tetrakis(N-methylpyridinium-4-yl) tetraiodide phthalocyanine impregnated to paper were evaluated. Photo-inactivation of microbes using inexpensive consumer light-emitting diode lamp was assessed on surface of dyed papers. Antimicrobial experiments of phthalocyanine-dyed paper by live cell assessment through colony forming units counting demonstrated 3.72 and 4.01 log reduction against Escherichia coli (E. coli) and Acinetobacter baylyi (A. baylyi) respectively after 1 h of illumination with 35 mW/cm 2 light. The porphyrin-dyed paper exhibited 1.66 and 2.01 log reduction in colony forming units against E. coli and A. baylyi respectively after 1 h exposure with 4 mW/cm 2 light. Both dyed papers were photo-stable after 64 h of continuous exposure with 42 mW/cm 2 light, while phthalocyanine-dyed paper exhibited superior leaching stability in phosphate-buffered saline. Copyright © 2018 Elsevier Inc. All rights reserved.
-
Morphine, but not Trauma, Sensitizes to Systemic Acinetobacter baumannii Infection
Breslow, Jessica M.; Monroy, M. Alexandra; Daly, John M.; Meissler, Joseph J.; Gaughan, John; Adler, Martin W.; Eisenstein, Toby K.
2014-01-01
Acinetobacter baumannii is an important nosocomial pathogen in civilian intensive care units. Recently the incidence has increased in wounded military personnel. Morphine is documented in numerous animal studies to be immunosuppressive and to sensitize to infection. The hypotheses were tested that morphine, administered for analgesia in the battlefield, predisposes to Acinetobacter infection, and that the opioid may have an additive or synergistic effect with trauma. To test these hypotheses, an intraperitoneal infection model was established in mice using several Acinetobacter strains. Morphine administered for 48 hr by implantation of a slow-release morphine pellet increased mortality compared to animals receiving a placebo pellet, an effect that was blocked by the mu-opioid receptor antagonist, naltrexone. Acinetobacter burdens in the blood, spleens, livers, and lungs of morphine-treated mice, were significantly higher than those in placebo-treated animals, confirming that mortality was due to potentiated growth of the bacteria. There were also elevated levels of pro-inflammatory cytokines in morphine-treated versus placebo-treated mice. Morphine caused a reduction in the total number of cells in the peritoneal cavity, a decrease in the percentage and total numbers of neutrophils, and a decrease in the total number of macrophages. Morphine treatment also suppressed levels of the neutrophil-inducing molecules, IL-17A and KC/CXCL1. However, IL-17A−/− mice given morphine were not sensitized to Acintobacter infection to a greater degree than similarly treated wild-type mice. Trauma alone did not sensitize to Acinetobacter infection, and there was no additive effect between morphine and trauma. These results support the hypothesis that morphine potentiates Acinetobacter infection. PMID:21826405
-
Morphine, but not trauma, sensitizes to systemic Acinetobacter baumannii infection.
Breslow, Jessica M; Monroy, M Alexandra; Daly, John M; Meissler, Joseph J; Gaughan, John; Adler, Martin W; Eisenstein, Toby K
2011-12-01
Acinetobacter baumannii is an important nosocomial pathogen in civilian intensive care units. Recently the incidence has increased in wounded military personnel. Morphine is documented in numerous animal studies to be immunosuppressive and to sensitize to infection. The hypotheses were tested that morphine, administered for analgesia in the battlefield, predisposes to Acinetobacter infection, and that the opioid may have an additive or synergistic effect with trauma. To test these hypotheses, an intraperitoneal infection model was established in mice using several Acinetobacter strains. Morphine administered for 48 h by implantation of a slow-release morphine pellet increased mortality compared to animals receiving a placebo pellet, an effect that was blocked by the mu-opioid receptor antagonist, naltrexone. Acinetobacter burdens in the blood, spleens, livers, and lungs of morphine-treated mice, were significantly higher than those in placebo-treated animals, confirming that mortality was due to potentiated growth of the bacteria. There were also elevated levels of pro-inflammatory cytokines in morphine-treated versus placebo-treated mice. Morphine caused a reduction in the total number of cells in the peritoneal cavity, a decrease in the percentage and total numbers of neutrophils, and a decrease in the total number of macrophages. Morphine treatment also suppressed levels of the neutrophil-inducing molecules, IL-17A and KC/CXCL1. However, IL-17A(-/-) mice given morphine were not sensitized to Acintobacter infection to a greater degree than similarly treated wild-type mice. Trauma alone did not sensitize to Acinetobacter infection, and there was no additive effect between morphine and trauma. These results support the hypothesis that morphine potentiates Acinetobacter infection.
-
Evolved aniline catabolism in Acinetobacter calcoaceticus during continuous culture of river water.
Wyndham, R C
1986-01-01
Adaptation of Acinetobacter calcoaceticus from river water to aniline depends on the dynamics of parent and mutant populations. The parent, Acinetobacter strain DON26 phenotype Ani0, was common in river water and assimilated aniline effectively at micromolar concentrations, but was inhibited at higher concentrations of aniline. The Ani0 phenotype was also characterized by a broad specificity for oxidation of chloroanilines by aniline-induced cells. The mutant Ani+ phenotype was represented by DON2, isolated from a population of less than 100 cells ml-1 in a mixed river water culture, and by DON261, isolated during continuous culture of DON26. Ani+ strains assimilated aniline at a greater maximum specific rate than the parent and were able to grow at concentrations of aniline greater than 16 mM. These strains cooxidized phenol after growth at high aniline concentrations, but showed reduced activity toward chloroanilines. These changes plus kinetic data, oxygen uptake data, and the results of auxanography indicate that the mutant has an increased activity and altered specificity of the initial enzyme in the aniline catabolic pathway. The parent strain, DON26, was at a selective advantage relative to the mutant at low concentrations of aniline, but was replaced by the mutant when aniline concentrations increased. Adaptation of the mixed river water community to aniline involved selection of both phenotypes. Reversion of the Ani+ to Ani0 phenotype occurred at a frequency of 10(-2) in the absence of aniline selection. Plasmid content was not altered during either acquisition or loss of the Ani+ phenotype. Adaptive changes in Acinetobacter spp. populations illustrate important differences in the catabolic activities of natural and pollutant selected strains.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:3707123
-
Purification and characterization of novel extracellular cholesterol esterase from Acinetobacter sp.
Du, Liangjun; Huo, Ying; Ge, Fanglan; Yu, Jiajun; Li, Wei; Cheng, Guiying; Yong, Bin; Zeng, Lihuang; Huang, Min
2010-12-01
CHE4-1, a bacterial strain that belongs to the genus Acinetobacter and expresses high level of inducible extracellular cholesterol esterase (CHE), was isolated from feces of carnivore Panthera pardus var. The cholesterol esterase of the strain CHE4-1 was purified by ultrafiltration followed with DEAE-Sepharose FF chromatography and Phenyl-Sepharose CL-4B chromatography, and then by Sephadex G-50 gel filtration. Different from other known microbial cholesterol esterase, the purified CHE from CHE4-1 strain is a monomer with molecular weight of 6.5 kD and has high activity to both long-chain and short-chain cholesterol ester. Enzymatic activity was enhanced in the presence of metal ion Ca(2+), Zn(2+) and boracic acid, and was not significantly affected by several detergents including sodium cholate, Triton X100 and Tween-80. The enzyme was found to be stable during long-term aqueous storage at 4 °C, indicating its potential as a clinical diagnostic reagent. To the best of our knowledge, this is the first report regarding purification and characterization of CHE from Acinetobacter sp. The results demonstrated that this particular CHE is a novel cholesterol esterase.
-
Rafei, Rayane; Dabboussi, Fouad; Hamze, Monzer; Eveillard, Matthieu; Lemarié, Carole; Gaultier, Marie-Pierre; Mallat, Hassan; Moghnieh, Rima; Husni-Samaha, Rola; Joly-Guillou, Marie-Laure; Kempf, Marie
2014-01-01
This study analyzed 42 Acinetobacter baumannii strains collected between 2009-2012 from different hospitals in Beyrouth and North Lebanon to better understand the epidemiology and carbapenem resistance mechanisms in our collection and to compare the robustness of pulsed field gel electrophoresis (PFGE), multilocus sequence typing (MLST), repetitive sequence-based PCR (rep-PCR) and blaOXA-51 sequence-based typing (SBT). Among 31 carbapenem resistant strains, we have detected three carbapenem resistance genes: 28 carried the blaOXA-23 gene, 1 the blaOXA-24 gene and 2 strains the blaOXA-58 gene. This is the first detection of blaOXA-23 and blaOXA-24 in Lebanon. PFGE identified 11 types and was the most discriminating technique followed by rep-PCR (9 types), blaOXA-51 SBT (8 types) and MLST (7 types). The PFGE type A'/ST2 was the dominant genotype in our collection present in Beyrouth and North Lebanon. The clustering agreement between all techniques was measured by adjust Wallace coefficient. An overall agreement has been demonstrated. High values of adjust Wallace coefficient were found with followed combinations: PFGE to predict MLST types = 100%, PFGE to predict blaOXA-51 SBT = 100%, blaOXA-51 SBT to predict MLST = 100%, MLST to predict blaOXA-51 SBT = 84.7%, rep-PCR to predict MLST = 81.5%, PFGE to predict rep-PCR = 69% and rep-PCR to predict blaOXA-51 SBT = 67.2%. PFGE and MLST are gold standard methods for outbreaks investigation and population structure studies respectively. Otherwise, these two techniques are technically, time and cost demanding. We recommend the use of blaOXA-51 SBT as first typing method to screen isolates and assign them to their corresponding clonal lineages. Repetitive sequence-based PCR is a rapid tool to access outbreaks but careful interpretation of results must be always performed.
-
Kimura, Yui; Harada, Kazuki; Shimizu, Takae; Sato, Tomomi; Kajino, Akari; Usui, Masaru; Tamura, Yutaka; Tsuyuki, Yuzo; Miyamoto, Tadashi; Ohki, Asami; Watarai, Masahisa
2018-05-12
We investigated the prevalence of virulence factors and antimicrobial resistance among 67 Acinetobacter spp. isolates, consisting of 21 Acinetobacter baumannii and 46 non-baumannii Acinetobacter from companion animals. The PCR analysis showed that the most prevalent virulence gene was afa/draBC (29.9%), followed by papC (22.4%) and cvaC (20.9%). Antimicrobial susceptibility testing revealed that resistance to gentamicin (14.9%) and ciprofloxacin (11.9%) was relatively prevalent. Five gentamicin- and/or ciprofloxacin-resistant A. baumannii strains were assigned to ST25, ST149, ST164, ST203, and ST1198. All ciprofloxacin-resistant isolates harbored point mutations in gyrA and/or parC. This is the first preliminary monitoring of animal-origin Acinetobacter spp. in Japan. © 2018 The Societies and John Wiley & Sons Australia, Ltd.
-
DOE Office of Scientific and Technical Information (OSTI.GOV)
Shah, Bhumika S., E-mail: bhumika.shah@mq.edu.au; Tetu, Sasha G.; Harrop, Stephen J.
2014-09-25
The structure of a short-chain dehydrogenase encoded within genomic islands of A. baumannii strains has been solved to 2.4 Å resolution. This classical SDR incorporates a flexible helical subdomain. The NADP-binding site and catalytic side chains are identified. Over 15% of the genome of an Australian clinical isolate of Acinetobacter baumannii occurs within genomic islands. An uncharacterized protein encoded within one island feature common to this and other International Clone II strains has been studied by X-ray crystallography. The 2.4 Å resolution structure of SDR-WM99c reveals it to be a new member of the classical short-chain dehydrogenase/reductase (SDR) superfamily. Themore » enzyme contains a nucleotide-binding domain and, like many other SDRs, is tetrameric in form. The active site contains a catalytic tetrad (Asn117, Ser146, Tyr159 and Lys163) and water molecules occupying the presumed NADP cofactor-binding pocket. An adjacent cleft is capped by a relatively mobile helical subdomain, which is well positioned to control substrate access.« less
-
López, M; Rueda, A; Florido, J P; Blasco, L; Fernández-García, L; Trastoy, R; Fernández-Cuenca, F; Martínez-Martínez, L; Vila, J; Pascual, A; Bou, G; Tomas, M
2018-02-06
In this study, we compared eighteen clinical strains of A. baumannii belonging to the ST-2 clone and isolated from patients in the same intensive care unit (ICU) in 2000 (9 strains referred to collectively as Ab_GEIH-2000) and 2010 (9 strains referred to collectively as Ab_GEIH-2010), during the GEIH-REIPI project (Umbrella BioProject PRJNA422585). We observed two main molecular differences between the Ab_GEIH-2010 and the Ab_GEIH-2000 collections, acquired over the course of the decade long sampling interval and involving the mobilome: i) a plasmid harbouring genes for bla OXA 24/40 ß-lactamase and abKA/abkB proteins of a toxin-antitoxin system; and ii) two temperate bacteriophages, Ab105-1ϕ (63 proteins) and Ab105-2ϕ (93 proteins), containing important viral defence proteins. Moreover, all Ab_GEIH-2010 strains contained a Quorum functional network of Quorum Sensing (QS) and Quorum Quenching (QQ) mechanisms, including a new QQ enzyme, AidA, which acts as a bacterial defence mechanism against the exogenous 3-oxo-C12-HSL. Interestingly, the infective capacity of the bacteriophages isolated in this study (Ab105-1ϕ and Ab105-2ϕ) was higher in the Ab_GEIH-2010 strains (carrying a functional Quorum network) than in the Ab_GEIH-2000 strains (carrying a deficient Quorum network), in which the bacteriophages showed little or no infectivity. This is the first study about the evolution of the Quorum network and the mobilome in clinical strains of Acinetobacter baumannii during a decade.
-
Derecho, I; McCoy, K B; Vaishampayan, P; Venkateswaran, K; Mogul, R
2014-10-01
The microbiological inventory of spacecraft and the associated assembly facility surfaces represent the primary pool of forward contaminants that may impact the integrity of life-detection missions. Herein, we report on the characterization of several strains of hydrogen peroxide-resistant Acinetobacter, which were isolated during the Mars Phoenix lander assembly. All Phoenix-associated Acinetobacter strains possessed very high catalase specific activities, and the specific strain, A. gyllenbergii 2P01AA, displayed a survival against hydrogen peroxide (no loss in 100 mM H2O2 for 1 h) that is perhaps the highest known among Gram-negative and non-spore-forming bacteria. Proteomic characterizations reveal a survival mechanism inclusive of proteins coupled to peroxide degradation (catalase and alkyl hydroperoxide reductase), energy/redox management (dihydrolipoamide dehydrogenase), protein synthesis/folding (EF-G, EF-Ts, peptidyl-tRNA hydrolase, DnaK), membrane functions (OmpA-like protein and ABC transporter-related protein), and nucleotide metabolism (HIT family hydrolase). Together, these survivability and biochemical parameters support the hypothesis that oxidative tolerance and the related biochemical features are the measurable phenotypes or outcomes for microbial survival in the spacecraft assembly facilities, where the low-humidity (desiccation) and clean (low-nutrient) conditions may serve as selective pressures. Hence, the spacecraft-associated Acinetobacter, due to the conferred oxidative tolerances, may ultimately hinder efforts to reduce spacecraft bioburden when using chemical sterilants, thus suggesting that non-spore-forming bacteria may need to be included in the bioburden accounting for future life-detection missions.
-
Heterotrophic nitrogen removal by Acinetobacter sp. Y1 isolated from coke plant wastewater.
Liu, YuXiang; Hu, Tingting; Song, Yujie; Chen, Hongping; Lv, YongKang
2015-11-01
A strain of Acinetobacter sp. Y1, which exhibited an amazing ability to remove ammonium, nitrite and nitrate, was isolated from the activated sludge of a coking wastewater treatment plant. The aim of this work was to study the ability, influence factors and possible pathway of nitrogen removal by Acinetobacter sp. Y1. Results showed that maximum removal rate of NH4(+)-N by the strain was 10.28 mg-N/L/h. Carbon source had significant influence on the growth and ammonium removal efficiencies of strain Y1. Pyruvate, citrate and acetate were favourable carbon sources for the strain. Temperature, pH value and shaking speed could affect the growth and nitrogen removal ability. Nitrate or nitrite could be used as a sole nitrogen source for the growth and removed efficiently by the strain. N2 levels increased to 53.74%, 50.21% and 55.13% within 36 h when 100 mg/L NH4(+)-N, NO2(-)-N or NO3(-) -N was used as sole nitrogen source in the gas detection experiment. The activities of hydroxylamine oxidoreductase (HAO), nitrate reductase (NR) and nitrite reductase (NiR), which are key enzymes in heterotrophic nitrification and aerobic denitrification, were all detectable in the strain. Consequently, a possible pathway for ammonium removal by the strain was also suggested. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
-
NASA Astrophysics Data System (ADS)
Li, Xiuyuan; Tang, Yanyan; Lu, Xinxin
2018-04-01
Currently, the capability of identification for Acinetobacter species using MALDI-TOF MS still remains unclear in clinical laboratories due to certain elusory phenomena. Thus, we conducted this research to evaluate this technique and reveal the causes of misidentification. Briefly, a total of 788 Acinetobacter strains were collected and confirmed at the species level by 16S rDNA and rpoB sequencing, and subsequently compared to the identification by MALDI-TOF MS using direct smear and bacterial extraction pretreatments. Cluster analysis was performed based on the mass spectra and 16S rDNA to reflect the diversity among different species. Eventually, 19 Acinetobacter species were confirmed, including 6 species unavailable in Biotyper 3.0 database. Another novel species was observed, temporarily named A. corallinus. The accuracy of identification for Acinetobacter species using MALDI-TOF MS was 97.08% (765/788), regardless of which pretreatment was applied. The misidentification only occurred on 3 A. parvus strains and 20 strains of species unavailable in the database. The proportions of strains with identification score ≥ 2.000 using direct smear and bacterial extraction pretreatments were 86.04% (678/788) and 95.43% (752/788), χ 2 = 41.336, P < 0.001. The species similar in 16 rDNA were discriminative from the mass spectra, such as A. baumannii & A. junii, A. pittii & A. calcoaceticus, and A. nosocomialis & A. seifertii. Therefore, using MALDI-TOF MS to identify Acinetobacter strains isolated from clinical samples was deemed reliable. Misidentification occurred occasionally due to the insufficiency of the database rather than sample extraction failure. We suggest gene sequencing should be performed when the identification score is under 2.000 even when using bacterial extraction pretreatment. [Figure not available: see fulltext.
-
Li, Xiuyuan; Tang, Yanyan; Lu, Xinxin
2018-04-09
Currently, the capability of identification for Acinetobacter species using MALDI-TOF MS still remains unclear in clinical laboratories due to certain elusory phenomena. Thus, we conducted this research to evaluate this technique and reveal the causes of misidentification. Briefly, a total of 788 Acinetobacter strains were collected and confirmed at the species level by 16S rDNA and rpoB sequencing, and subsequently compared to the identification by MALDI-TOF MS using direct smear and bacterial extraction pretreatments. Cluster analysis was performed based on the mass spectra and 16S rDNA to reflect the diversity among different species. Eventually, 19 Acinetobacter species were confirmed, including 6 species unavailable in Biotyper 3.0 database. Another novel species was observed, temporarily named A. corallinus. The accuracy of identification for Acinetobacter species using MALDI-TOF MS was 97.08% (765/788), regardless of which pretreatment was applied. The misidentification only occurred on 3 A. parvus strains and 20 strains of species unavailable in the database. The proportions of strains with identification score ≥ 2.000 using direct smear and bacterial extraction pretreatments were 86.04% (678/788) and 95.43% (752/788), χ 2 = 41.336, P < 0.001. The species similar in 16 rDNA were discriminative from the mass spectra, such as A. baumannii & A. junii, A. pittii & A. calcoaceticus, and A. nosocomialis & A. seifertii. Therefore, using MALDI-TOF MS to identify Acinetobacter strains isolated from clinical samples was deemed reliable. Misidentification occurred occasionally due to the insufficiency of the database rather than sample extraction failure. We suggest gene sequencing should be performed when the identification score is under 2.000 even when using bacterial extraction pretreatment. Graphical Abstract ᅟ.
-
Kuzi, S; Blum, S E; Kahane, N; Adler, A; Hussein, O; Segev, G; Aroch, I
2016-11-01
Members of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex cause severe outbreaks in humans, and are increasingly reported in animals. A retrospective study, describing a severe outbreak in dogs and cats caused by a multidrug resistant member of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in a veterinary hospital, between July 2010 and November 2012. The study included 19 dogs and 4 cats. Acinetobacter calcoaceticus-Acinetobacter baumannii complex bacteria were isolated from urine (9 animals), respiratory tract (11), tissues (3) and blood (1). The most common infection-associated findings included fever, purulent discharge from endotracheal tubes, hypotension, and neutropaenia. Infections led to pneumonia, urinary tract infection, cellulitis and sepsis. Infection was transmitted in the intensive care unit, where 22 of 23 animals were initially hospitalised. The mortality rate was 70% (16 of 23 animals), and was higher in cases of respiratory infection compared to other infections. Aggressive environmental cleaning and disinfection, with staff education for personal hygiene and antisepsis, sharply decreased the infection incidence. Health care-associated outbreaks with multidrug resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex in dogs and cats are potentially highly fatal and difficult to eradicate, warranting monitoring, antiseptic techniques and judicious antibiotic use. © 2016 British Small Animal Veterinary Association.
-
Copper Resistance of the Emerging Pathogen Acinetobacter baumannii
Williams, Caitlin L.; Neu, Heather M.; Gilbreath, Jeremy J.; Michel, Sarah L. J.; Zurawski, Daniel V.
2016-01-01
ABSTRACT Acinetobacter baumannii is an important emerging pathogen that is capable of causing many types of severe infection, especially in immunocompromised hosts. Since A. baumannii can rapidly acquire antibiotic resistance genes, many infections are on the verge of being untreatable, and novel therapies are desperately needed. To investigate the potential utility of copper-based antibacterial strategies against Acinetobacter infections, we characterized copper resistance in a panel of recent clinical A. baumannii isolates. Exposure to increasing concentrations of copper in liquid culture and on solid surfaces resulted in dose-dependent and strain-dependent effects; levels of copper resistance varied broadly across isolates, possibly resulting from identified genotypic variation among strains. Examination of the growth-phase-dependent effect of copper on A. baumannii revealed that resistance to copper increased dramatically in stationary phase. Moreover, A. baumannii biofilms were more resistant to copper than planktonic cells but were still susceptible to copper toxicity. Exposure of bacteria to subinhibitory concentrations of copper allowed them to better adapt to and grow in high concentrations of copper; this copper tolerance response is likely achieved via increased expression of copper resistance mechanisms. Indeed, genomic analysis revealed numerous putative copper resistance proteins that share amino acid homology to known proteins in Escherichia coli and Pseudomonas aeruginosa. Transcriptional analysis revealed significant upregulation of these putative copper resistance genes following brief copper exposure. Future characterization of copper resistance mechanisms may aid in the search for novel antibiotics against Acinetobacter and other highly antibiotic-resistant pathogens. IMPORTANCE Acinetobacter baumannii causes many types of severe nosocomial infections; unfortunately, some isolates have acquired resistance to almost every available antibiotic
-
van Belkum, Alex; Halimi, Diane; Bonetti, Eve-Julie; Renzi, Gesuele; Cherkaoui, Abdessalam; Sauvonnet, Véronique; Martelin, Roland; Durand, Géraldine; Chatellier, Sonia; Zambardi, Gilles; Engelhardt, Anette; Karlsson, Åsa; Schrenzel, Jacques
2015-01-01
Precise assessment of potential therapeutic synergy, antagonism or indifference between antimicrobial agents currently depends on time-consuming and hard-to-standardize in vitro chequerboard titration methods. We here present a method based on a novel two-dimensional antibiotic gradient technique named Xact™. We used a test comprising a combination of perpendicular gradients of meropenem and colistin in a single quadrant. We compared test outcomes with those obtained with classical chequerboard microbroth dilution testing in a study involving 27 unique strains of multidrug-resistant Acinetobacter baumannii from diverse origins. We were able to demonstrate 92% concordance between the new technology and classical chequerboard titration using the A. baumannii collection. Two strains could not be analysed by Xact™ due to their out-of-range MIC of meropenem (>128 mg/L). The new test was shown to be diagnostically useful, easy to implement and less labour intensive than the classical method. © The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
-
Novel Therapies for Acinetobacter Osteomyelitis
2009-01-01
deployed soldiers. An additional problem is that while there are some effective antibiotics against Acinetobacter (i.e. Colistin and Imipenem ), they are...of Acinetobacter baumannii with confirmed resistance to amikacin, ampicillin, aztraeonam, ceftriaxone, ciprofloxacin, gentamicin, imipenem
-
Signature Motifs Identify an Acinetobacter Cif Virulence Factor with Epoxide Hydrolase Activity*
Bahl, Christopher D.; Hvorecny, Kelli L.; Bridges, Andrew A.; Ballok, Alicia E.; Bomberger, Jennifer M.; Cady, Kyle C.; O'Toole, George A.; Madden, Dean R.
2014-01-01
Endocytic recycling of the cystic fibrosis transmembrane conductance regulator (CFTR) is blocked by the CFTR inhibitory factor (Cif). Originally discovered in Pseudomonas aeruginosa, Cif is a secreted epoxide hydrolase that is transcriptionally regulated by CifR, an epoxide-sensitive repressor. In this report, we investigate a homologous protein found in strains of the emerging nosocomial pathogens Acinetobacter nosocomialis and Acinetobacter baumannii (“aCif”). Like Cif, aCif is an epoxide hydrolase that carries an N-terminal secretion signal and can be purified from culture supernatants. When applied directly to polarized airway epithelial cells, mature aCif triggers a reduction in CFTR abundance at the apical membrane. Biochemical and crystallographic studies reveal a dimeric assembly with a stereochemically conserved active site, confirming our motif-based identification of candidate Cif-like pathogenic EH sequences. Furthermore, cif expression is transcriptionally repressed by a CifR homolog (“aCifR”) and is induced in the presence of epoxides. Overall, this Acinetobacter protein recapitulates the essential attributes of the Pseudomonas Cif system and thus may facilitate airway colonization in nosocomial lung infections. PMID:24474692
-
Reservoirs of Non-baumannii Acinetobacter Species
Al Atrouni, Ahmad; Joly-Guillou, Marie-Laure; Hamze, Monzer; Kempf, Marie
2016-01-01
Acinetobacter spp. are ubiquitous gram negative and non-fermenting coccobacilli that have the ability to occupy several ecological niches including environment, animals and human. Among the different species, Acinetobacter baumannii has evolved as global pathogen causing wide range of infection. Since the implementation of molecular techniques, the habitat and the role of non-baumannii Acinetobacter in human infection have been elucidated. In addition, several new species have been described. In the present review, we summarize the recent data about the natural reservoir of non-baumannii Acinetobacter including the novel species that have been described for the first time from environmental sources and reported during the last years. PMID:26870013
-
Resources for Genetic and Genomic Analysis of Emerging Pathogen Acinetobacter baumannii
Ramage, Elizabeth; Weiss, Eli J.; Radey, Matthew; Hayden, Hillary S.; Held, Kiara G.; Huse, Holly K.; Zurawski, Daniel V.; Brittnacher, Mitchell J.; Manoil, Colin
2015-01-01
ABSTRACT Acinetobacter baumannii is a Gram-negative bacterial pathogen notorious for causing serious nosocomial infections that resist antibiotic therapy. Research to identify factors responsible for the pathogen's success has been limited by the resources available for genome-scale experimental studies. This report describes the development of several such resources for A. baumannii strain AB5075, a recently characterized wound isolate that is multidrug resistant and displays robust virulence in animal models. We report the completion and annotation of the genome sequence, the construction of a comprehensive ordered transposon mutant library, the extension of high-coverage transposon mutant pool sequencing (Tn-seq) to the strain, and the identification of the genes essential for growth on nutrient-rich agar. These resources should facilitate large-scale genetic analysis of virulence, resistance, and other clinically relevant traits that make A. baumannii a formidable public health threat. IMPORTANCE Acinetobacter baumannii is one of six bacterial pathogens primarily responsible for antibiotic-resistant infections that have become the scourge of health care facilities worldwide. Eliminating such infections requires a deeper understanding of the factors that enable the pathogen to persist in hospital environments, establish infections, and resist antibiotics. We present a set of resources that should accelerate genome-scale genetic characterization of these traits for a reference isolate of A. baumannii that is highly virulent and representative of current outbreak strains. PMID:25845845
-
Janssen, D B; Jager, D; Witholt, B
1987-01-01
A 1,6-dichlorohexane-degrading strain of Acinetobacter sp. was isolated from activated sludge. The organism could grow with and quantitatively release halide from 1,6-dichlorohexane, 1,9-dichlorononane, 1-chloropentane, 1-chlorobutane, 1-bromopentane, ethylbromide, and 1-iodopropane. Crude extracts contained an inducible novel dehalogenase that liberated halide from the above compounds and also from 1,3-dichloropropane, 1,2-dibromoethane, and 2-bromoethanol. The latter two compounds were toxic suicide substrates for the organism at concentrations of 10 and 5 microM, respectively. Mutants resistant to 1,2-dibromoethane (3 mM) lacked dehalogenase activity and did not utilize haloalkanes for growth. Mutants resistant to both 1,2-dibromoethane (3 mM) and 2-bromoethanol (30 mM) could no longer oxidize or utilize alcohols and were capable of hydrolytic dehalogenation of 1,2-dibromoethane to ethylene glycol. PMID:3579270
-
de Léséleuc, Louis; Harris, Greg; KuoLee, Rhonda; Xu, H Howard; Chen, Wangxue
2014-05-01
Bacteremia caused by Acinetobacter baumannii is a highly lethal complication of hospital-acquired pneumonia. In the present study, we investigated the serum resistance, gallium nitrate tolerance and heme consumption of A. baumannii strain LAC-4 which was recently reported to display high virulence in a mouse pneumonia model with extrapulmonary dissemination leading to fatal bacteremia. This strain showed enhanced growth in mouse and fetal bovine serum that was independent of complement and was not observed with regular growth media. The LAC-4 strain was found to possess a high tolerance to gallium nitrate (GaN), whereas serum synergized with GaN in inhibiting A. baumannii strain ATCC 17978. We found that LAC-4 contains a heme oxygenase gene and expresses a highly efficient heme consumption system. This system can be fully blocked in vitro and in vivo by gallium protoporphyrin IX (GaPPIX). Inhibition of heme consumption by GaPPIX completely abrogated the growth advantage of LAC-4 in serum as well as its tolerance to GaN. More importantly, GaPPIX treatment of mice intranasally infected with LAC-4 prevented extrapulmonary dissemination and death. Thus, we propose that heme provides an additional source of iron for LAC-4 to bypass iron restriction caused by serum transferrin, lactoferrin or free gallium salts. Heme consumption systems in A. baumannii may constitute major virulence factors for lethal bacteremic isolates. Copyright © 2014 Crown Copyright and Elsevier Inc. Published by Elsevier GmbH.. All rights reserved.
-
Röttig, Annika; Strittmatter, Carl Simon; Schauer, Jennifer; Hiessl, Sebastian; Daniel, Rolf
2016-01-01
ABSTRACT Recently, we isolated a novel Streptomyces strain which can accumulate extraordinarily large amounts of triacylglycerol (TAG) and consists of 64% fatty acids (dry weight) when cultivated with glucose and 50% fatty acids (dry weight) when cultivated with cellobiose. To identify putative gene products responsible for lipid storage and cellobiose utilization, we analyzed its draft genome sequence. A single gene encoding a wax ester synthase/acyl coenzyme A (CoA):diacylglycerol acyltransferase (WS/DGAT) was identified and heterologously expressed in Escherichia coli. The purified enzyme AtfG25 showed acyltransferase activity with C12- or C16-acyl-CoA, C12 to C18 alcohols, or dipalmitoyl glycerol. This acyltransferase exhibits 24% amino acid identity to the model enzyme AtfA from Acinetobacter baylyi but has high sequence similarities to WS/DGATs from other Streptomyces species. To investigate the impact of AtfG25 on lipid accumulation, the respective gene, atfG25, was inactivated in Streptomyces sp. strain G25. However, cells of the insertion mutant still exhibited DGAT activity and were able to store TAG, albeit in lower quantities and at lower rates than the wild-type strain. These findings clearly indicate that AtfG25 has an important, but not exclusive, role in TAG biosynthesis in the novel Streptomyces isolate and suggest the presence of alternative metabolic pathways for lipid accumulation which are discussed in the present study. IMPORTANCE A novel Streptomyces strain was isolated from desert soil, which represents an extreme environment with high temperatures, frequent drought, and nutrient scarcity. We believe that these harsh conditions promoted the development of the capacity for this strain to accumulate extraordinarily large amounts of lipids. In this study, we present the analysis of its draft genome sequence with a special focus on enzymes potentially involved in its lipid storage. Furthermore, the activity and importance of the detected
-
Weber, Theresa; Bechthold, Maren; Winkler, Tobias; Dauselt, John; Terfort, Andreas
2013-11-01
Direct grafting of hyperbranched polyglycerol (PG) layers onto the oxide surfaces of steel, aluminum, and silicon has been achieved through surface-initiated polymerization of 2-hydroxymethyloxirane (glycidol). Optimization of the deposition conditions led to a protocol that employed N-methyl-2-pyrrolidone (NMP) as the solvent and temperatures of 100 and 140 °C, depending on the substrate material. In all cases, a linear growth of the PG layers could be attained, which allows for control of film thickness by altering the reaction time. At layer thicknesses >5 nm, the PG layers completely suppressed the adhesion of albumin, fibrinogen, and globulin. These layers were also at least 90% bio-repulsive for two bacteria strains, E. coli and Acinetobacter baylyi, with further improvement being observed when the PG film thickness was increased to 17 nm (up to 99.9% bio-repulsivity on silicon). Copyright © 2013 Elsevier B.V. All rights reserved.
-
Perron, Gabriel G.; Lee, Alexander E. G.; Wang, Yun; Huang, Wei E.; Barraclough, Timothy G.
2012-01-01
Bacterial recombination is believed to be a major factor explaining the prevalence of multi-drug-resistance (MDR) among pathogenic bacteria. Despite extensive evidence for exchange of resistance genes from retrospective sequence analyses, experimental evidence for the evolutionary benefits of bacterial recombination is scarce. We compared the evolution of MDR between populations of Acinetobacter baylyi in which we manipulated both the recombination rate and the initial diversity of strains with resistance to single drugs. In populations lacking recombination, the initial presence of multiple strains resistant to different antibiotics inhibits the evolution of MDR. However, in populations with recombination, the inhibitory effect of standing diversity is alleviated and MDR evolves rapidly. Moreover, only the presence of DNA harbouring resistance genes promotes the evolution of resistance, ruling out other proposed benefits for recombination. Together, these results provide direct evidence for the fitness benefits of bacterial recombination and show that this occurs by mitigation of functional interference between genotypes resistant to single antibiotics. Although analogous to previously described mechanisms of clonal interference among alternative beneficial mutations, our results actually highlight a different mechanism by which interactions among co-occurring strains determine the benefits of recombination for bacterial evolution. PMID:22048956
-
Zhu, Lingxiang; Yan, Zhongqiang; Zhang, Zhaojun; Zhou, Qiming; Zhou, Jinchun; Wakeland, Edward K; Fang, Xiangdong; Xuan, Zhenyu; Shen, Dingxia; Li, Quan-Zhen
2013-01-01
The emergence and rapid spreading of multidrug-resistant Acinetobacter baumannii strains has become a major health threat worldwide. To better understand the genetic recombination related with the acquisition of drug-resistant elements during bacterial infection, we performed complete genome analysis on three newly isolated multidrug-resistant A. baumannii strains from Beijing using next-generation sequencing technology. Whole genome comparison revealed that all 3 strains share some common drug resistant elements including carbapenem-resistant bla OXA-23 and tetracycline (tet) resistance islands, but the genome structures are diversified among strains. Various genomic islands intersperse on the genome with transposons and insertions, reflecting the recombination flexibility during the acquisition of the resistant elements. The blood-isolated BJAB07104 and ascites-isolated BJAB0868 exhibit high similarity on their genome structure with most of the global clone II strains, suggesting these two strains belong to the dominant outbreak strains prevalent worldwide. A large resistance island (RI) of about 121-kb, carrying a cluster of resistance-related genes, was inserted into the ATPase gene on BJAB07104 and BJAB0868 genomes. A 78-kb insertion element carrying tra-locus and bla OXA-23 island, can be either inserted into one of the tniB gene in the 121-kb RI on the chromosome, or transformed to conjugative plasmid in the two BJAB strains. The third strains of this study, BJAB0715, which was isolated from spinal fluid, exhibit much more divergence compared with above two strains. It harbors multiple drug-resistance elements including a truncated AbaR-22-like RI on its genome. One of the unique features of this strain is that it carries both bla OXA-23 and bla OXA-58 genes on its genome. Besides, an Acinetobacter lwoffii adeABC efflux element was found inserted into the ATPase position in BJAB0715. Our comparative analysis on currently completed Acinetobacter baumannii
-
Jones, Crystal L; Singh, Shweta S; Alamneh, Yonas; Casella, Leila G; Ernst, Robert K; Lesho, Emil P; Waterman, Paige E; Zurawski, Daniel V
2017-03-01
The loss of fitness in colistin-resistant (CR) Acinetobacter baumannii was investigated using longitudinal isolates from the same patient. Early CR isolates were outcompeted by late CR isolates for growth in broth and survival in the lungs of mice. Fitness loss was associated with an increased susceptibility to oxidative stress since early CR strains had reduced in vitro survival in the presence of hydrogen peroxide and decreased catalase activity compared to that of late CR and colistin-susceptible (CS) strains. Copyright © 2017 Jones et al.
-
Kurth, Daniel; Belfiore, Carolina; Gorriti, Marta F.; Cortez, Néstor; Farias, María E.; Albarracín, Virginia H.
2015-01-01
Ultraviolet radiation can damage biomolecules, with detrimental or even lethal effects for life. Even though lower wavelengths are filtered by the ozone layer, a significant amount of harmful UV-B and UV-A radiation reach Earth’s surface, particularly in high altitude environments. high-altitude Andean lakes (HAALs) are a group of disperse shallow lakes and salterns, located at the Dry Central Andes region in South America at altitudes above 3,000 m. As it is considered one of the highest UV-exposed environments, HAAL microbes constitute model systems to study UV-resistance mechanisms in environmental bacteria at various complexity levels. Herein, we present the genome sequence of Acinetobacter sp. Ver3, a gammaproteobacterium isolated from Lake Verde (4,400 m), together with further experimental evidence supporting the phenomenological observations regarding this bacterium ability to cope with increased UV-induced DNA damage. Comparison with the genomes of other Acinetobacter strains highlighted a number of unique genes, such as a novel cryptochrome. Proteomic profiling of UV-exposed cells identified up-regulated proteins such as a specific cytoplasmic catalase, a putative regulator, and proteins associated to amino acid and protein synthesis. Down-regulated proteins were related to several energy-generating pathways such as glycolysis, beta-oxidation of fatty acids, and electronic respiratory chain. To the best of our knowledge, this is the first report on a genome from a polyextremophilic Acinetobacter strain. From the genomic and proteomic data, an “UV-resistome” was defined, encompassing the genes that would support the outstanding UV-resistance of this strain. PMID:25954258
-
Kurth, Daniel; Belfiore, Carolina; Gorriti, Marta F; Cortez, Néstor; Farias, María E; Albarracín, Virginia H
2015-01-01
Ultraviolet radiation can damage biomolecules, with detrimental or even lethal effects for life. Even though lower wavelengths are filtered by the ozone layer, a significant amount of harmful UV-B and UV-A radiation reach Earth's surface, particularly in high altitude environments. high-altitude Andean lakes (HAALs) are a group of disperse shallow lakes and salterns, located at the Dry Central Andes region in South America at altitudes above 3,000 m. As it is considered one of the highest UV-exposed environments, HAAL microbes constitute model systems to study UV-resistance mechanisms in environmental bacteria at various complexity levels. Herein, we present the genome sequence of Acinetobacter sp. Ver3, a gammaproteobacterium isolated from Lake Verde (4,400 m), together with further experimental evidence supporting the phenomenological observations regarding this bacterium ability to cope with increased UV-induced DNA damage. Comparison with the genomes of other Acinetobacter strains highlighted a number of unique genes, such as a novel cryptochrome. Proteomic profiling of UV-exposed cells identified up-regulated proteins such as a specific cytoplasmic catalase, a putative regulator, and proteins associated to amino acid and protein synthesis. Down-regulated proteins were related to several energy-generating pathways such as glycolysis, beta-oxidation of fatty acids, and electronic respiratory chain. To the best of our knowledge, this is the first report on a genome from a polyextremophilic Acinetobacter strain. From the genomic and proteomic data, an "UV-resistome" was defined, encompassing the genes that would support the outstanding UV-resistance of this strain.
-
Sun, Xiaoyu; Liu, Bin; Chen, Yan; Huang, Honglan; Wang, Guoqing; Li, Fan; Ni, Zhaohui
2016-12-01
The prevalence of various Ambler class A to D β-lactamases, ISAba1, and class 1 and 2 integrons as well as the clonal relatedness in 105 Acinetobacter spp. isolates found in northeastern China was investigated. All 105 Acinetobacter spp. isolates were determined to be multidrug resistant (MDR), and the resistance rates to carbapenem agents were approximately 50%. PER, IMP, AmpC, and OXA-23 were found to be dominant β-lactamases belonging to different classes, respectively. This is the first report of the coexistence of bla PER , bla IMP , bla AmpC , and bla OXA-23-like genes in Acinetobacter spp. isolates from northeastern China. ISAba1 was found upstream of the bla OXA-23-like gene in 87.8% (36/41) strains and upstream of the bla OXA-51-like gene in 26.5% (13/49) strains. ISAba3-like element was found upstream of the bla OXA-58-like gene in one bla OXA-58-like -positive strain. The presence of IntI1 was detected in 63.8% (67/105) of the isolates and the most prevalent gene cassettes were aacA4, aadA1, and catB8. The highly prevalent isolates belong to international clonal lineage (ICL)-II. These results indicate that the wide horizontal and clonal spread of MDR Acinetobacter spp. isolates harbouring multiple β-lactamase genes has become a serious problem in northeastern China.
-
Harris, Greg; Kuo Lee, Rhonda; Lam, Christopher K.; Kanzaki, Gregory; Patel, Girishchandra B.; Xu, H. Howard
2013-01-01
Acinetobacter baumannii is an important emerging pathogen in health care-acquired infections and is responsible for severe nosocomial and community-acquired pneumonia. Currently available mouse models of A. baumannii pneumonia show poor colonization with little to no extrapulmonary dissemination. Here, we describe a mouse model of A. baumannii pneumonia using a clinical isolate (LAC-4 strain) that reliably reproduces the most relevant features of human pulmonary A. baumannii infection and pathology. Using this model, we have shown that LAC-4 infection induced rapid bacterial replication in the lungs, significant extrapulmonary dissemination, and severe bacteremia by 24 h postintranasal inoculation. Infected mice showed severe bronchopneumonia and dilatation and inflammatory cell infiltration in the perivascular space. More significantly, 100% of C57BL/6 and BALB/c mice succumbed to 108 CFU of LAC-4 inoculation within 48 h. When this model was used to assess the efficacy of antimicrobials, all mice treated with imipenem and tigecycline survived a lethal intranasal challenge, with minimal clinical signs and body weight loss. Moreover, intranasal immunization of mice with formalin-fixed LAC-4 protected 40% of mice from a lethal (100× 100% lethal dose) intraperitoneal challenge. Thus, this model offers a reproducible acute course of A. baumannii pneumonia without requiring additional manipulation of host immune status, which will facilitate the development of therapeutic agents and vaccines against A. baumannii pneumonia in humans. PMID:23689726
-
Wan Nor Amilah, W A W; Noor Izani, N J; Ng, W K; Ashraful Haq, J
2012-12-01
Clinical utilization of carbapenems remains under threat with the emergence of acquired carbapenemase-producing bacteria, particularly metallo-β-lactamases (MBL). Rapid detection of MBL-producing Gram-negative bacilli is essential to prevent their widespread dissemination. However, no standardized detection method is available for routine laboratory use. The purpose of the study was to evaluate a chelating-agent based double disk synergic test and disk potentiation test for MBL-producing strain detection and to determine the isolation rate of MBL-producing Pseudomonas aeruginosa and Acinetobacter from clinical samples in our tertiary teaching hospital. A total of 22 and 66 imipenem-resistant P. aeruginosa and Acinetobacter isolates respectively were tested with ceftazidime (CAZ) disk by modified double disk synergic test and disk potentiation test using ethylenediaminetetraacetic acid (EDTA) and 2-mercaptopropionic acid (as chelating agents) to detect MBL production. The tests were compared with EDTA-phenanthroline-imipenem (EPI) microdilution MIC test as gold standard. MBL positive strains were detected in 17 (77.3%) P. aeruginosa and 2 (3.5%) Acinetobacter isolates. The disk potentiation test with 2-mercaptopropionic acid (2-MPA) dilution of 1:12 provided the most acceptable sensitivities and specificities (88.2% sensitivity and 100% specificity in P. aeruginosa; 100% sensitivity and specificity in Acinetobacter) compared to other screening methods used in this study. This study provided useful information on the local prevalence of MBL-producing P. aeruginosa and Acinetobacter in our hospital. Disc potentiation test with CAZ/2-MPA disc appears to be reliable and convenient MBL detection method in the routine clinical laboratory.
-
Identification of Acinetobacter seifertii isolated from Bolivian hospitals.
Cerezales, Mónica; Xanthopoulou, Kyriaki; Ertel, Julia; Nemec, Alexandr; Bustamante, Zulema; Seifert, Harald; Gallego, Lucia; Higgins, Paul G
2018-06-01
Acinetobacter seifertii is a recently described species that belongs to the Acinetobacter calcoaceticus-Acinetobacter baumannii complex. It has been recovered from clinical samples and is sometimes associated with antimicrobial resistance determinants. We present here the case of three A. seifertii clinical isolates which were initially identified as Acinetobacter sp. by phenotypic methods but no identification at the species level was achieved using semi-automated identification methods. The isolates were further analysed by whole genome sequencing and identified as A. seifertii. Due to the fact that A. seifertii has been isolated from serious infections such as respiratory tract and bloodstream infections, we emphasize the importance of correctly identifying isolates of the genus Acinetobacter at the species level to gain a deeper knowledge of their prevalence and clinical impact.
-
Tsachouridou, Olga; Georgiou, Adamantini; Nanoudis, Sideris; Chrysanthidis, Theofilos; Loli, Georgia; Morfesis, Petros; Zebekakis, Pantelis; Metallidis, Symeon
2017-07-08
The incidence of infectious spondylodiscitis has been increasing over the last few years. This reflects the expanding elderly and immunocompromised populations and the rising implementation of invasive spinal procedures. Infection may be inoculated into the disc space directly during invasive spinal procedures. Osteomyelitis caused by Acinetobacter species is rare and mainly caused by multidrug-resistant strains. We present the case of a 72-year-old Greek woman with postoperative spondylodiscitis caused by a multidrug-resistant Acinetobacter baumannii strain that was successfully treated, after she declined surgical treatment, with prolonged and high dosage of tigecycline. She received intravenously administered tigecycline 200 mg per day for 60 days and then 100 mg per day for a total of 102 days and was infection-free. We reviewed the literature on the role of Acinetobacter baumannii as a cause of osteomyelitis, emphasizing the difficulty of treatment and the potential role of tigecycline in conservative treatment of the infection. We believe that 102 days in total is the longest time that any patient has received tigecycline in the literature, thus our patient is a unique case of successful treatment of spondylodiscitis.
-
Enzymes of the Isoleucine-Valine Pathway in Acinetobacter
Twarog, Robert
1972-01-01
Regulation of four of the enzymes required for isoleucine and valine biosynthesis in Acinetobacter was studied. A three- to fourfold derepression of acetohydroxyacid synthetase was routinely observed in two different wild-type strains when grown in minimal medium relative to cells grown in minimal medium supplemented with leucine, valine, and isoleucine. A similar degree of synthetase derepression was observed in appropriately grown isoleucine or leucine auxotrophs. No significant derepression of threonine deaminase or transaminase B occurred in either wild-type or mutant cells grown under a variety of conditions. Three amino acid analogues were tested with wild-type cells; except for a two- to threefold derepression of dihydroxyacid dehydrase when high concentrations of aminobutyric acid were added to the medium, essentially the same results were obtained. Experiments showed that threonine deaminase is subject to feedback inhibition by isoleucine and that valine reverses this inhibition. Cooperative effects in threonine deaminase were demonstrated with crude extracts. The data indicate that the synthesis of isoleucine and valine in Acinetobacter is regulated by repression control of acetohydroxyacid synthetase and feedback inhibition of threonine deaminase and acetohydroxyacid synthetase. PMID:4669215
-
Intravenous Minocycline: A Review in Acinetobacter Infections.
Greig, Sarah L; Scott, Lesley J
2016-10-01
Intravenous minocycline (Minocin ® ) is approved in the USA for use in patients with infections due to susceptible strains of Gram-positive and Gram-negative pathogens, including infections due to Acinetobacter spp. Minocycline is a synthetic tetracycline derivative that was originally introduced in the 1960s. A new intravenous formulation of minocycline was recently approved and introduced to address the increasing prevalence of multidrug-resistant (MDR) pathogens. Minocycline shows antibacterial activity against A. baumannii clinical isolates worldwide, and exhibits synergistic bactericidal activity against MDR and extensively drug-resistant (XDR) A. baumannii isolates when combined with other antibacterial agents. In retrospective studies, intravenous minocycline provided high rates of clinical success or improvement and was generally well tolerated among patients with MDR or carbapenem-resistant A. baumannii infections. While randomized clinical trial data would be useful to fully establish the place of minocycline in the management of these infections for which there are currently very few available options, clinical trials in patients with infections due to Acinetobacter spp. are difficult to perform. Nevertheless, current data indicate a potential role for intravenous minocycline in the treatment of patients MDR A. baumannii infections, particularly when combined with a second antibacterial agent (e.g. colistin).
-
The Genomic Diversification of the Whole Acinetobacter Genus: Origins, Mechanisms, and Consequences
Touchon, Marie; Cury, Jean; Yoon, Eun-Jeong; Krizova, Lenka; Cerqueira, Gustavo C.; Murphy, Cheryl; Feldgarden, Michael; Wortman, Jennifer; Clermont, Dominique; Lambert, Thierry; Grillot-Courvalin, Catherine; Nemec, Alexandr; Courvalin, Patrice; Rocha, Eduardo P.C.
2014-01-01
Bacterial genomics has greatly expanded our understanding of microdiversification patterns within a species, but analyses at higher taxonomical levels are necessary to understand and predict the independent rise of pathogens in a genus. We have sampled, sequenced, and assessed the diversity of genomes of validly named and tentative species of the Acinetobacter genus, a clade including major nosocomial pathogens and biotechnologically important species. We inferred a robust global phylogeny and delimited several new putative species. The genus is very ancient and extremely diverse: Genomes of highly divergent species share more orthologs than certain strains within a species. We systematically characterized elements and mechanisms driving genome diversification, such as conjugative elements, insertion sequences, and natural transformation. We found many error-prone polymerases that may play a role in resistance to toxins, antibiotics, and in the generation of genetic variation. Surprisingly, temperate phages, poorly studied in Acinetobacter, were found to account for a significant fraction of most genomes. Accordingly, many genomes encode clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems with some of the largest CRISPR-arrays found so far in bacteria. Integrons are strongly overrepresented in Acinetobacter baumannii, which correlates with its frequent resistance to antibiotics. Our data suggest that A. baumannii arose from an ancient population bottleneck followed by population expansion under strong purifying selection. The outstanding diversification of the species occurred largely by horizontal transfer, including some allelic recombination, at specific hotspots preferentially located close to the replication terminus. Our work sets a quantitative basis to understand the diversification of Acinetobacter into emerging resistant and versatile pathogens. PMID:25313016
-
De novo Biosynthesis of Biodiesel by Escherichia coli in Optimized Fed-Batch Cultivation
Cai, Ke; Tan, Xiaoming; Lu, Xuefeng
2011-01-01
Biodiesel is a renewable alternative to petroleum diesel fuel that can contribute to carbon dioxide emission reduction and energy supply. Biodiesel is composed of fatty acid alkyl esters, including fatty acid methyl esters (FAMEs) and fatty acid ethyl esters (FAEEs), and is currently produced through the transesterification reaction of methanol (or ethanol) and triacylglycerols (TAGs). TAGs are mainly obtained from oilseed plants and microalgae. A sustainable supply of TAGs is a major bottleneck for current biodiesel production. Here we report the de novo biosynthesis of FAEEs from glucose, which can be derived from lignocellulosic biomass, in genetically engineered Escherichia coli by introduction of the ethanol-producing pathway from Zymomonas mobilis, genetic manipulation to increase the pool of fatty acyl-CoA, and heterologous expression of acyl-coenzyme A: diacylglycerol acyltransferase from Acinetobacter baylyi. An optimized fed-batch microbial fermentation of the modified E. coli strain yielded a titer of 922 mg L−1 FAEEs that consisted primarily of ethyl palmitate, -oleate, -myristate and -palmitoleate. PMID:21629774
-
Gonzalez-Villoria, Ana Maria; Valverde-Garduno, Veronica
2016-01-01
Antibiotic-resistant infectious bacteria currently imply a high risk and therefore constitute a strong challenge when treating patients in hospital settings. Characterization of these species and of particular strains is a priority for the establishment of diagnostic tests and preventive procedures. The relevance of Acinetobacter baumannii as a problematic microorganism in inpatient facilities, particularly intensive care units, has increased over time. This review aims to draw attention to (i) the historical emergence of carbapenem-resistant Acinetobacter baumannii, (ii) the current status of surveillance needs in Latin America, and (iii) recent data suggesting that A. baumannii continues to spread and evolve in hospital settings. First, we present synopsis of the series of events leading to the discovery and precise identification of this microorganism in hospital settings. Then key events in the acquisition of antibiotic-resistant genes by this microorganism are summarized, highlighting the race between new antibiotic generation and emergence of A. baumannii resistant strains. Here we review the historical development of this species as an infectious threat, the current state of its distribution, and antibiotic resistance characteristics, and we discuss future prospects for its control. PMID:26966582
-
Mohanty, Srujana; Maurya, Vijeta; Gaind, Rajni; Deb, Monorama
2013-11-15
Pseudomonas aeruginosa and Acinetobcter spp. are important nosocomial pathogens and carbapenem resistance is an emerging threat. Therapeutic options for infections with these isolates include colistin. This study was conducted to determine the prevalence of carbapenem resistance in P. aeruginosa and Acinetobacter spp. bloodstream isolates, phenotypically characterize the resistance mechanisms and evaluate the in vitro activity of colistin. Consecutive 145 (95 P.aeruginosa and 50 Acinetobacter spp.) non-repeat isolates were included. Antibiotic susceptibility testing was performed per CLSI guidelines. MIC for carbapenems and colistin was performed using Etest. Isolates showing reduced susceptibility or resistance to the carbapenems were tested for metallo-β-lactamase (MBL) production using imipenem-EDTA combined disk and MBL Etest. Carbapenem resistance was observed in 40% P. aeruginosa and 66.0% Acinetobacter spp. Carbapenem-resistant (CA-R) isolates were significantly (p <0.05) more frequently resistant to the other antibiotics than carbapenem-susceptible isolates. Approximately half of the CA-R strains were multidrug-resistant, and 3.1-5.5% were resistant to all antibiotics tested. MBL was found in 76.3% and 69.7% of the P. aeruginosa and Acinetobacter spp., respectively. Colistin resistance was observed in three (6.0%) Acinetobacter isolates and eight (8.4%) P. aeruginosa. MIC50 for carbapenems were two to four times higher for MBL-positive compared to MBL-negative isolates, but no difference was seen in MIC for colistin. Carbapenem resistance was observed to be mediated by MBL in a considerable number of isolates. Colistin is an alternative for infections caused by CA-R isolates; however, MIC testing should be performed whenever clinical use of colistin is considered.
-
Acinetobacter baumannii: a universal threat to public health?
Giamarellou, Helen; Antoniadou, Anastasia; Kanellakopoulou, Kyriaki
2008-08-01
Acinetobacter spp. are non-fermentative, strictly aerobic, Gram-negative microorganisms with a confusing taxonomic history. The Acinetobacter baumannii-Acinetobacter calcoaceticus complex is the species most commonly isolated from clinical specimens. It is ubiquitous in nature and has been found as part of the normal skin, throat and rectal flora as well as in food and body lice. It colonises patients in Intensive Care Units and contaminates inanimate hospital surfaces and devices as well as wounds, including war injuries. Although a frequent coloniser, Acinetobacter can be the cause of severe and sometimes lethal infections, mostly of nosocomial origin, predominantly ventilator-associated pneumonia. Bacteraemic infections are rare but may evolve to septic shock. Acinetobacter also emerges as a cause of nosocomial outbreaks and is characterised by increasing antimicrobial multiresistance. Antibiotic use, especially carbapenems and third-generation cephalosporins, is recognised as the most important risk factor for multiresistance. Described resistance mechanisms include hydrolysis by beta-lactamases, alterations in outer membrane proteins and penicillin-binding proteins, and increased activity of efflux pumps. Today, Acinetobacter resistant to carbapenems, aminoglycosides and fluoroquinolones presents a challenge to the clinician. However, sulbactam, tigecycline and colistin represent the current therapeutic approaches, which are associated with satisfactory efficacy.
-
Characterisation of Pellicles Formed by Acinetobacter baumannii at the Air-Liquid Interface
Nait Chabane, Yassine; Marti, Sara; Rihouey, Christophe; Alexandre, Stéphane; Hardouin, Julie; Lesouhaitier, Olivier; Vila, Jordi; Kaplan, Jeffrey B.; Jouenne, Thierry; Dé, Emmanuelle
2014-01-01
The clinical importance of Acinetobacter baumannii is partly due to its natural ability to survive in the hospital environment. This persistence may be explained by its capacity to form biofilms and, interestingly, A. baumannii can form pellicles at the air-liquid interface more readily than other less pathogenic Acinetobacter species. Pellicles from twenty-six strains were morphologically classified into three groups: I) egg-shaped (27%); II) ball-shaped (50%); and III) irregular pellicles (23%). One strain representative of each group was further analysed by Brewster’s Angle Microscopy to follow pellicle development, demonstrating that their formation did not require anchoring to a solid surface. Total carbohydrate analysis of the matrix showed three main components: Glucose, GlcNAc and Kdo. Dispersin B, an enzyme that hydrolyzes poly-N-acetylglucosamine (PNAG) polysaccharide, inhibited A. baumannii pellicle formation, suggesting that this exopolysaccharide contributes to pellicle formation. Also associated with the pellicle matrix were three subunits of pili assembled by chaperon-usher systems: the major CsuA/B, A1S_1510 (presented 45% of identity with the main pilin F17-A from enterotoxigenic Escherichia coli pili) and A1S_2091. The presence of both PNAG polysaccharide and pili systems in matrix of pellicles might contribute to the virulence of this emerging pathogen. PMID:25360550
-
Whole-cell bacterial bioreporter for actively searching and sensing of alkanes and oil spills.
Zhang, Dayi; He, Yi; Wang, Yun; Wang, Hui; Wu, Lin; Aries, Eric; Huang, Wei E
2012-01-01
Acinetobacter baylyi ADP1 was found to tolerate seawater and have a special ability of adhering to an oil-water interface of 10-80 µm emulsified mineral and crude oil droplets. These properties make ADP1 an ideal bacterial chassis for constructing bioreporters that are able to actively search and sense oil spill in water and soils. Acinetobacter baylyi bioreporter ADPWH_alk was developed and applied to the detection of alkanes and alkenes in water, seawater and soils. Bioreporter ADPWH_alk was able to detect a broad range of alkanes and alkenes with carbon chain length from C7 to C36. So far, ADPWH_alk is the only bioreporter that is able to detect alkane with carbon chain length greater than C18. This bioreporter responded to the alkanes in about 30 min and it was independent to the cell growth phase because of two point mutations in alkM promoter recognized by alkane regulatory protein ALKR. ADPWH_alk was applied to detect mineral oil, Brent, Chestnut and Sirri crude oils in water and seawater in the range 0.1-100 mg l(-1), showing that the bioreporter oil detection was semi-quantitative. This study demonstrates that ADPWH_alk is a rapid, sensitive and semi-quantitative bioreporter that can be useful for environmental monitoring and assessment of oil spills in seawater and soils. © 2011 The Authors. Microbial Biotechnology © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.
-
Zhang, Ying; Wang, Yang; Wang, Zhi-Gang; Wang, Xi; Guo, Huo-Sheng; Meng, Dong-Fang; Wong, Po-Keung
2012-01-01
Statistical experimental designs provided by statistical analysis system (SAS) software were applied to optimize the fermentation medium composition for the production of atrazine-degrading Acinetobacter sp. DNS(32) in shake-flask cultures. A "Plackett-Burman Design" was employed to evaluate the effects of different components in the medium. The concentrations of corn flour, soybean flour, and K(2)HPO(4) were found to significantly influence Acinetobacter sp. DNS(32) production. The steepest ascent method was employed to determine the optimal regions of these three significant factors. Then, these three factors were optimized using central composite design of "response surface methodology." The optimized fermentation medium composition was composed as follows (g/L): corn flour 39.49, soybean flour 25.64, CaCO(3) 3, K(2)HPO(4) 3.27, MgSO(4)·7H(2)O 0.2, and NaCl 0.2. The predicted and verifiable values in the medium with optimized concentration of components in shake flasks experiments were 7.079 × 10(8) CFU/mL and 7.194 × 10(8) CFU/mL, respectively. The validated model can precisely predict the growth of atrazine-degraing bacterium, Acinetobacter sp. DNS(32).
-
The genomic diversification of the whole Acinetobacter genus: origins, mechanisms, and consequences.
Touchon, Marie; Cury, Jean; Yoon, Eun-Jeong; Krizova, Lenka; Cerqueira, Gustavo C; Murphy, Cheryl; Feldgarden, Michael; Wortman, Jennifer; Clermont, Dominique; Lambert, Thierry; Grillot-Courvalin, Catherine; Nemec, Alexandr; Courvalin, Patrice; Rocha, Eduardo P C
2014-10-13
Bacterial genomics has greatly expanded our understanding of microdiversification patterns within a species, but analyses at higher taxonomical levels are necessary to understand and predict the independent rise of pathogens in a genus. We have sampled, sequenced, and assessed the diversity of genomes of validly named and tentative species of the Acinetobacter genus, a clade including major nosocomial pathogens and biotechnologically important species. We inferred a robust global phylogeny and delimited several new putative species. The genus is very ancient and extremely diverse: Genomes of highly divergent species share more orthologs than certain strains within a species. We systematically characterized elements and mechanisms driving genome diversification, such as conjugative elements, insertion sequences, and natural transformation. We found many error-prone polymerases that may play a role in resistance to toxins, antibiotics, and in the generation of genetic variation. Surprisingly, temperate phages, poorly studied in Acinetobacter, were found to account for a significant fraction of most genomes. Accordingly, many genomes encode clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems with some of the largest CRISPR-arrays found so far in bacteria. Integrons are strongly overrepresented in Acinetobacter baumannii, which correlates with its frequent resistance to antibiotics. Our data suggest that A. baumannii arose from an ancient population bottleneck followed by population expansion under strong purifying selection. The outstanding diversification of the species occurred largely by horizontal transfer, including some allelic recombination, at specific hotspots preferentially located close to the replication terminus. Our work sets a quantitative basis to understand the diversification of Acinetobacter into emerging resistant and versatile pathogens. © The Author(s) 2014. Published by Oxford University Press on behalf of the Society
-
Bilocq, Florence; Jennes, Serge; Verbeken, Gilbert; Rose, Thomas; Keersebilck, Elkana; Bosmans, Petra; Pieters, Thierry; Hing, Mony; Heuninckx, Walter; De Pauw, Frank; Soentjens, Patrick; Merabishvili, Maia; Deschaght, Pieter; Vaneechoutte, Mario; Bogaerts, Pierre; Glupczynski, Youri; Pot, Bruno; van der Reijden, Tanny J.; Dijkshoorn, Lenie
2016-01-01
Multidrug resistant Acinetobacter baumannii and its closely related species A. pittii and A. nosocomialis, all members of the Acinetobacter calcoaceticus-baumannii (Acb) complex, are a major cause of hospital acquired infection. In the burn wound center of the Queen Astrid military hospital in Brussels, 48 patients were colonized or infected with Acb complex over a 52-month period. We report the molecular epidemiology of these organisms, their clinical impact and infection control measures taken. A representative set of 157 Acb complex isolates was analyzed using repetitive sequence-based PCR (rep-PCR) (DiversiLab) and a multiplex PCR targeting OXA-51-like and OXA-23-like genes. We identified 31 rep-PCR genotypes (strains). Representatives of each rep-type were identified to species by rpoB sequence analysis: 13 types to A. baumannii, 10 to A. pittii, and 3 to A. nosocomialis. It was assumed that isolates that belonged to the same rep-type also belonged to the same species. Thus, 83.4% of all isolates were identified to A. baumannii, 9.6% to A. pittii and 4.5% to A. nosocomialis. We observed 12 extensively drug resistant Acb strains (10 A. baumannii and 2 A. nosocomialis), all carbapenem-non-susceptible/colistin-susceptible and imported into the burn wound center through patients injured in North Africa. The two most prevalent rep-types 12 and 13 harbored an OXA-23-like gene. Multilocus sequence typing allocated them to clonal complex 1 corresponding to EU (international) clone I. Both strains caused consecutive outbreaks, interspersed with periods of apparent eradication. Patients infected with carbapenem resistant A. baumannii were successfully treated with colistin/rifampicin. Extensive infection control measures were required to eradicate the organisms. Acinetobacter infection and colonization was not associated with increased attributable mortality. PMID:27223476
-
De Vos, Daniel; Pirnay, Jean-Paul; Bilocq, Florence; Jennes, Serge; Verbeken, Gilbert; Rose, Thomas; Keersebilck, Elkana; Bosmans, Petra; Pieters, Thierry; Hing, Mony; Heuninckx, Walter; De Pauw, Frank; Soentjens, Patrick; Merabishvili, Maia; Deschaght, Pieter; Vaneechoutte, Mario; Bogaerts, Pierre; Glupczynski, Youri; Pot, Bruno; van der Reijden, Tanny J; Dijkshoorn, Lenie
2016-01-01
Multidrug resistant Acinetobacter baumannii and its closely related species A. pittii and A. nosocomialis, all members of the Acinetobacter calcoaceticus-baumannii (Acb) complex, are a major cause of hospital acquired infection. In the burn wound center of the Queen Astrid military hospital in Brussels, 48 patients were colonized or infected with Acb complex over a 52-month period. We report the molecular epidemiology of these organisms, their clinical impact and infection control measures taken. A representative set of 157 Acb complex isolates was analyzed using repetitive sequence-based PCR (rep-PCR) (DiversiLab) and a multiplex PCR targeting OXA-51-like and OXA-23-like genes. We identified 31 rep-PCR genotypes (strains). Representatives of each rep-type were identified to species by rpoB sequence analysis: 13 types to A. baumannii, 10 to A. pittii, and 3 to A. nosocomialis. It was assumed that isolates that belonged to the same rep-type also belonged to the same species. Thus, 83.4% of all isolates were identified to A. baumannii, 9.6% to A. pittii and 4.5% to A. nosocomialis. We observed 12 extensively drug resistant Acb strains (10 A. baumannii and 2 A. nosocomialis), all carbapenem-non-susceptible/colistin-susceptible and imported into the burn wound center through patients injured in North Africa. The two most prevalent rep-types 12 and 13 harbored an OXA-23-like gene. Multilocus sequence typing allocated them to clonal complex 1 corresponding to EU (international) clone I. Both strains caused consecutive outbreaks, interspersed with periods of apparent eradication. Patients infected with carbapenem resistant A. baumannii were successfully treated with colistin/rifampicin. Extensive infection control measures were required to eradicate the organisms. Acinetobacter infection and colonization was not associated with increased attributable mortality.
-
Nkem, Bruno Martins; Halimoon, Normala; Yusoff, Fatimah Md; Johari, Wan Lufti Wan; Zakaria, Mohamad Pauzi; Medipally, Srikanth Reddy; Kannan, Narayanan
2016-06-15
In this study, we isolated two indigenous hydrocarbon-degrading bacteria from tarball found in Rhu Sepuluh beach, Terengganu, Malaysia. These bacteria were identified based on their physiological characteristic and 16S rRNA gene sequence analysis, and they showed 99% similarity with Cellulosimicrobium cellulans DSM 43879 and Acinetobacter baumannii ATCC 19606 respectively. Their hydrocarbon-degrading capabilities were tested using diesel-oil as sole carbon source. Results analysed using GC-MS, showed diesel-oil alkanes were degraded an average 64.4% by C. cellulans and 58.1% by A. baumannii with medium optical density reaching 0.967 (C. cellulans) and 1.515 (A. baumannii) in minimal salt media at 32°C for 10days. Individual diesel-oil alkanes were degraded between 10%-95.4% by C. cellulans and 0.2%-95.9% by A. baumannii. Both strains utilized diesel-oil for growth. The study suggests both strains are part of indigenous hydrocarbon-degrading bacteria in tarball with potential for bioremediation of oil-polluted marine environment. Copyright © 2016 Elsevier Ltd. All rights reserved.
-
Nosocomial infections due to Acinetobacter calcoaceticus.
Zaer, F; Deodhar, L
1989-01-01
Fifty four isolates of Acinetobacter calcoaceticus were studied in a period of 6 months. Maximum isolates were from burns cases and environmental sampling from burns ward also grew the same organism, indicating their role as nosocomial pathogen. Acinetobacter may initially be mistaken for Neisseria species. As the organisms show multidrug resistance to commonly used antibiotics their correct identification is important.
-
Detection of Multi-drug Resistant Acinetobacter Lwoffii Isolated from Soil of Mink Farm.
Sun, Na; Wen, Yong Jun; Zhang, Shu Qin; Zhu, Hong Wei; Guo, Li; Wang, Feng Xue; Chen, Qiang; Ma, Hong Xia; Cheng, Shi Peng
2016-07-01
There were 4 Acinetobacter lwoffii obtained from soil samples. The antimicrobial susceptibility of the strains to 16 antimicrobial agents was investigated using K-B method. Three isolates showed the multi-drug resistance. The presence of resistance genes and integrons was determined using PCR. The aadA1, aac(3')-IIc, aph(3')-VII, aac(6')-Ib, sul2, cat2, floR, and tet(K) genes were detected, respectively. Three class 1 integrons were obtained. The arr-3-aacA4 and blaPSE-1 gene cassette, which cause resistance to aminoglycoside and beta-lactamase antibiotics. Our results reported the detection of multi-drug resistant and carried resistant genes Acinetobacter lwoffii from soil. The findings suggested that we should pay close attention to the prevalence of multi-drug resistant bacterial species of environment. Copyright © 2016 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.
-
Enright, M C; Carter, P E; MacLean, I A; McKenzie, H
1994-07-01
We obtained 16S ribosomal DNA (rDNA) sequence data for strains belonging to 11 species of Proteobacteria, including the type strains of Kingella kingae, Neisseria lactamica, Neisseria meningitidis, Moraxella lacunata subsp. lacunata, [Neisseria] ovis, Moraxella catarrhalis, Moraxella osloensis, [Moraxella] phenylpyruvica, and Acinetobacter lwoffii, as well as strains of Neisseria subflava and Acinetobacter calcoaceticus. The data in a distance matrix constructed by comparing the sequences supported the proposal that the genera Acinetobacter and Moraxella and [N.] ovis should be excluded from the family Neisseriaceae. Our results are consistent with hybridization data which suggest that these excluded taxa should be part of a new family, the Moraxellaceae. The strains that we studied can be divided into the following five groups: (i) M. lacunata subsp. lacunata, [N.] ovis, and M. catarrhalis; (ii) M. osloensis; (iii) [M.] phenylpyruvica; (iv) A. calcoaceticus and A. lwoffii; and (v) N. meningitidis, N. subflava, N. lactamica, and K. kingae. We agree with the previous proposal that [N.] ovis should be renamed Moraxella ovis, as this organism is closely related to Moraxella species and not to Neisseria species. The generically misnamed taxon [M.] phenylpyruvica belongs to the proposed family Moraxellaceae, but it is sufficiently different to warrant exclusion from the genus Moraxella. Further work needs to be done to investigate genetically similar species, such as Psychrobacter immobilis, before the true generic position of this organism can be determined. Automated 16S rDNA sequencing with the PCR allows workers to accurately determine phylogenetic relationships between groups of organisms.(ABSTRACT TRUNCATED AT 250 WORDS)
-
Su, Jun-Feng; Shi, Jing-Xin; Huang, Ting-Lin; Ma, Fang
2016-08-15
A novel aerobic denitrification and biomineralization strain CN86 was isolated from the Qu Jiang artificial lake. Based on phylogenetic characteristics, the isolated strain was identified as Acinetobacter species. Strain CN86 was confirmed to have the ability to perform simultaneous denitrification and biomineralization. Exponential decay equation was used for the matching of kinetic processes on denitrification and biomineralization. A highest nitrate removal rate was achieved at the pH7.0, organic concentration of 1.5g/L and temperature of 30°C. An optimal hardness removal rate was obtained at the pH9.0, organic concentration of 2.0g/L and temperature of 30°C. Strain CN86 is a suitable candidate for the simultaneous removal of nitrate and hardness in groundwater treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.
-
Ackerman, Dorothy L; Craft, Kelly M; Doster, Ryan S; Weitkamp, Jörn-Hendrik; Aronoff, David M; Gaddy, Jennifer A; Townsend, Steven D
2018-03-09
In a previous study, we reported that human milk oligosaccharides (HMOs) isolated from five donor milk samples possessed antimicrobial and antibiofilm activity against Streptococcus agalactiae, also known as Group B Streptococcus or GBS. Herein, we present a broader evaluation of the antimicrobial and antibiofilm activity by screening HMOs from 14 new donors against three strains of GBS and two of the ESKAPE pathogens of particular interest to child health, Staphylococcus aureus and Acinetobacter baumannii. Growth and biofilm assays showed that HMOs from these new donors possessed antimicrobial and antibiofilm activity against all three strains of GBS, antibiofilm activity against methicillin-resistant S. aureus strain USA300, and antimicrobial activity against A. baumannii strain ATCC 19606.
-
Nanoparticles for Control of Biofilms of Acinetobacter Species
Singh, Richa; Nadhe, Shradhda; Wadhwani, Sweety; Shedbalkar, Utkarsha; Chopade, Balu Ananda
2016-01-01
Biofilms are the cause of 80% of microbial infections. Acinetobacter species have emerged as multi- and pan-drug-resistant bacteria and pose a great threat to human health. These act as nosocomial pathogens and form excellent biofilms, both on biotic and abiotic surfaces, leading to severe infections and diseases. Various methods have been developed for treatment and control of Acinetobacter biofilm including photodynamic therapy, radioimmunotherapy, prophylactic vaccines and antimicrobial peptides. Nanotechnology, in the present scenario, offers a promising alternative. Nanomaterials possess unique properties, and multiple bactericidal mechanisms render them more effective than conventional drugs. This review intends to provide an overview of Acinetobacter biofilm and the significant role of various nanoparticles as anti-biofouling agents, surface-coating materials and drug-delivery vehicles for biofilm control and treatment of Acinetobacter infections. PMID:28773507
-
Metabolism of spacecraft cleaning reagents by Mars Odyssey and Phoenix-associated Acinetobacter
NASA Astrophysics Data System (ADS)
Mogul, Rakesh; Barding, Gregory; Baki, Ryan; Perkins, Nicole; Lee, Sooji; Lalla, Sid; Campos, Alexa; Sripong, Kimberly; Madrid, Steve
2016-07-01
The metabolomic and proteomic properties that promote microbial survival in spacecraft assembly facilities are important aspects to planetary protection and astrobiology. In this presentation, we will provide molecular and biological evidence that the spacecraft-associated Acinetobacter metabolize/degrade spacecraft cleaning reagents such as ethanol, 2-propanol, and Kleenol-30. Gas chromatography-mass spectrometry (GC-MS) studies on A. radioresistens 50v1 (Mars Odyssey) show that the metabolome is dependent upon growth conditions and that ^{13}C-labeled ethanol is incorporated into metabolites such as TCA/glyoxylate cycle intermediates, amino acids, monosaccharides, and disaccharides (e.g., trehalose). In fact, plate count assays show that ethanol is a sole carbon source under minimal conditions for several Mars Phoenix and Odyssey-associated Acinetobacter strains, which may explain why the Acinetobacter are among the most abundant genera found in spacecraft assembly facilities. Biochemical analyses support the enzymatic oxidation of ethanol and 2-propanol by a membrane-bound and NAD+/PQQ-dependent alcohol dehydrogenase, with current kinetic data providing similar apparent K _{M} and maximum growth rate values of ˜5 and 8 mM ethanol, respectively. Preliminary GC-MS analysis also suggests that Kleenol-30 is degraded by A. radioresistens 50v1 when grown in ethanol mixtures. Under minimal conditions, A. radioresistens 50v1 (˜10 ^{8} cfu/mL) also displays a remarkable oxidative extremotolerance (˜2-log reduction in 10 mM hydrogen peroxide), which suggests crucial roles for metabolites associated with oxidative stress (e.g., trehalose) and the observed appreciable catalase specific activities. In conclusion, these results provide key insights into the survival strategies of spacecraft-associated Acinetobacter and emphasize the importance of characterizing the carbon metabolism of forward contaminants.
-
Isolation of Acinetobacter from Soil and Water
Baumann, Paul
1968-01-01
An enrichment culture procedure for isolating members of the genus Acinetobacter from soil and water is described. It involves the use of vigorously aerated mineral media at relative low pH, supplemented with acetate or other suitable carbon source and nitrate as nitrogen source. With this method, virtually all samples of soil and water yielded representatives of this genus. Semiquantitative comparisons of the numbers of Acinetobacter and of all bacteria capable of aerobic growth in a complex medium revealed that Acinetobacter constituted no less than 0.001% of the total heterotrophic aerobic population in soil and water and was one of the predominant organisms in some water samples. PMID:4874313
-
Wang, Hualiang; Wang, Jinghua; Yu, Peijuan; Ge, Ping; Jiang, Yanqun; Xu, Rong; Chen, Rong; Liu, Xuejie
2017-02-01
This study aimed to investigate antibiotic resistance genes in the multidrug-resistant (MDR) Acinetobacter baumannii (A. baumanii) strain, MDR-SHH02, using whole‑genome sequencing (WGS). The antibiotic resistance of MDR-SHH02 isolated from a patient with breast cancer to 19 types of antibiotics was determined using the Kirby‑Bauer method. WGS of MDR-SHH02 was then performed. Following quality control and transcriptome assembly, functional annotation of genes was conducted, and the phylogenetic tree of MDR-SHH02, along with another 5 A. baumanii species and 2 Acinetobacter species, was constructed using PHYLIP 3.695 and FigTree v1.4.2. Furthermore, pathogenicity islands (PAIs) were predicted by the pathogenicity island database. Potential antibiotic resistance genes in MDR-SHH02 were predicted based on the information in the Antibiotic Resistance Genes Database (ARDB). MDR-SHH02 was found to be resistant to all of the tested antibiotics. The total draft genome length of MDR-SHH02 was 4,003,808 bp. There were 74.25% of coding sequences to be annotated into 21 of the Clusters of Orthologous Groups (COGs) of protein terms, such as 'transcription' and 'amino acid transport and metabolism'. Furthermore, there were 45 PAIs homologous to the sequence MDRSHH02000806. Additionally, a total of 12 gene sequences in MDR-SHH02 were highly similar to the sequences of antibiotic resistance genes in ARDB, including genes encoding aminoglycoside‑modifying enzymes [e.g., aac(3)-Ia, ant(2'')‑Ia, aph33ib and aph(3')-Ia], β-lactamase genes (bl2b_tem and bl2b_tem1), sulfonamide-resistant dihydropteroate synthase genes (sul1 and sul2), catb3 and tetb. These results suggest that numerous genes mediate resistance to various antibiotics in MDR-SHH02, and provide a clinical guidance for the personalized therapy of A. baumannii-infected patients.
-
Quantitative proteomics to study carbapenem resistance in Acinetobacter baumannii
Tiwari, Vishvanath; Tiwari, Monalisa
2014-01-01
Acinetobacter baumannii is an opportunistic pathogen causing pneumonia, respiratory infections and urinary tract infections. The prevalence of this lethal pathogen increases gradually in the clinical setup where it can grow on artificial surfaces, utilize ethanol as a carbon source. Moreover it resists desiccation. Carbapenems, a β-lactam, are the most commonly prescribed drugs against A. baumannii. Resistance against carbapenem has emerged in Acinetobacter baumannii which can create significant health problems and is responsible for high morbidity and mortality. With the development of quantitative proteomics, a considerable progress has been made in the study of carbapenem resistance of Acinetobacter baumannii. Recent updates showed that quantitative proteomics has now emerged as an important tool to understand the carbapenem resistance mechanism in Acinetobacter baumannii. Present review also highlights the complementary nature of different quantitative proteomic methods used to study carbapenem resistance and suggests to combine multiple proteomic methods for understanding the response to antibiotics by Acinetobacter baumannii. PMID:25309531
-
López, Maria; Blasco, Lucia; Gato, Eva; Perez, Astrid; Fernández-Garcia, Laura; Martínez-Martinez, Luis; Fernández-Cuenca, Felipe; Rodríguez-Baño, Jesús; Pascual, Alvaro; Bou, German; Tomás, Maria
2017-01-01
Introduction: Acinetobacter baumannii is an opportunistic nosocomial pathogen associated with multiple infections. This pathogen usually colonizes (first stage of microbial infection) host tissues that are in contact with the external environment. As one of the sites of entry in human hosts is the gastrointestinal tract, the pathogen must be capable of tolerating bile salts. However, studies analyzing the molecular characteristics involved in the response to bile salts in clinical strains of A. baumannii are scarce. Material and Methods: Microbiological and transcriptional studies (arrays and RT-PCR) in the response to bile salts were carried out in isogenic (A. baumanni ΔadeB ATCC 17978 and A. baumannii ΔadeL ATCC 17978) and clinical strains from clone ST79/PFGE-HUI-1 which is characterized by lacking the AdeABC efflux pump and by overexpression the AdeFGH efflux pump. Results and Discussion: In presence of bile salts, in addition to the glutamate/aspartate transporter were found overexpressed in A. baumannii ΔadeB ATCC 17978, the virulence factors (surface motility, biofilm, and Type VI Secretion System) which are associated with activation of the Quorum Sensing system. Overexpression of these factors was confirmed in clinical strains of clone ST79/PFGE-HUI-1. Conclusions: This the first study about the adaptive response to bile salts investigating the molecular and microbiological characteristics in response to bile salts of an isogenic model of A. baumannii ATCC 17978 and clinical isolates of A. baumannii (clinical strains of ST79/PFGE-HUI-1) lacking the main RND efflux pump (AdeABC). Clinical isolates of A. baumannii lacking the AdeABC efflux pump (clone ST79/PFGE-HUI-1) displayed a new clinical profile (increased invasiveness) possibly associated with the response to stress conditions (such as the presence of bile salts). PMID:28536672
-
Denys, G A; Davis, J C; O'Hanley, P D; Stephens, J T
2011-07-01
We evaluated the in vitro and in vivo activity of a novel topical myeloperoxidase-mediated antimicrobial, E-101 solution, against 5 multidrug-resistant Acinetobacter baumannii isolates recovered from wounded American soldiers. Time-kill studies demonstrated rapid bactericidal activity against all A. baumannii strains tested in the presence of 3% blood. The in vitro bactericidal activity of E-101 solution against A. baumannii strains was confirmed in a full-thickness excision rat model. Additional in vivo studies appear warranted.
-
Gordon, N. C.; Wareham, D. W.
2009-01-01
CHROMagar Acinetobacter was used to screen stool and perineal swabs for enteric carriage of multidrug-resistant Acinetobacter baumannii in samples from critically ill patients. Results were compared with a molecular assay resulting in sensitivity and specificity of culture compared to PCR of 91.7% and 89.6%, respectively. PMID:19439546
-
Chee, Chin-Soon; Tan, Irene Kit-Ping; Alias, Zazali
2014-01-01
Glutathione transferases (GST) were purified from locally isolated bacteria, Acinetobacter calcoaceticus Y1, by glutathione-affinity chromatography and anion exchange, and their substrate specificities were investigated. SDS-polyacrylamide gel electrophoresis revealed that the purified GST resolved into a single band with a molecular weight (MW) of 23 kDa. 2-dimensional (2-D) gel electrophoresis showed the presence of two isoforms, GST1 (pI 4.5) and GST2 (pI 6.2) with identical MW. GST1 was reactive towards ethacrynic acid, hydrogen peroxide, 1-chloro-2,4-dinitrobenzene, and trans,trans-hepta-2,4-dienal while GST2 was active towards all substrates except hydrogen peroxide. This demonstrated that GST1 possessed peroxidase activity which was absent in GST2. This study also showed that only GST2 was able to conjugate GSH to isoproturon, a herbicide. GST1 and GST2 were suggested to be similar to F0KLY9 (putative glutathione S-transferase) and F0KKB0 (glutathione S-transferase III) of Acinetobacter calcoaceticus strain PHEA-2, respectively. PMID:24892084
-
Acinetobacter bacteraemia in Thailand: evidence for infections outside the hospital setting
PORTER, K. A.; RHODES, J.; DEJSIRILERT, S.; HENCHAICHON, S.; SILUDJAI, D.; THAMTHITIWAT, S.; PRAPASIRI, P.; JORAKATE, P.; KAEWPAN, A.; PERUSKI, L. F.; KERDSIN, A.; PRASERT, K.; YUENPRAKONE, S.; MALONEY, S. A.; BAGGETT, H. C.
2015-01-01
SUMMARY Acinetobacter is a well-recognized nosocomial pathogen. Previous reports of community-associated Acinetobacter infections have lacked clear case definitions and assessment of healthcare-associated (HCA) risk factors. We identified Acinetobacter bacteraemia cases from blood cultures obtained <3 days after hospitalization in rural Thailand and performed medical record reviews to assess HCA risk factors in the previous year and compare clinical and microbiological characteristics between cases with and without HCA risk factors. Of 72 Acinetobacter cases, 32 (44%) had no HCA risk factors. Compared to HCA infections, non-HCA infections were more often caused by Acinetobacter species other than calcoaceticus–baumannii complex species and by antibiotic-susceptible organisms. Despite similar symptoms, the case-fatality proportion was lower in non-HCA than HCA cases (9% vs. 45%, P < 0·01). Clinicians should be aware of Acinetobacter as a potential cause of community-associated infections in Thailand; prospective studies are needed to improve understanding of associated risk factors and disease burden. PMID:24001479
-
Isolation and Characterization of Rhamnolipid-Producing Bacterial Strains from a Biodiesel Facility
USDA-ARS?s Scientific Manuscript database
Novel strains of rhamnolipid-producing bacteria were isolated from soils at a biodiesel facility on the basis of their ability to grow on glycerol as a sole carbon source. Strains were identified as Acinetobacter calcoaceticus, Enterobacter asburiae, E. hormaecheii, Pantoea stewartii and Pseudomona...
-
Gkorezis, Panagiotis; Bottos, Eric M; Van Hamme, Jonathan D; Franzetti, Andrea; Abbamondi, Gennaro Roberto; Balseiro-Romero, Maria; Weyens, Nele; Rineau, Francois; Vangronsveld, Jaco
2015-08-13
The 3.94-Mb draft genome of Acinetobacter calcoaceticus GK1, a hydrocarbonoclastic plant growth-promoting Gram-negative rhizospheric bacterium, is presented here. Isolated at the Ford Motor Company site in Genk, Belgium, from poplar trees planted on a diesel-contaminated plume, GK1 is useful for enhancing hydrocarbon phytoremediation. Copyright © 2015 Gkorezis et al.
-
Guo, Xing; Liu, Bianfang; Gao, Lina; Zhou, Yuan; Shan, Yuanyuan; Lü, Xin
2018-06-01
Excessive nitrite in food is potentially harmful to human health because of its carcinogenic effects caused by nitroso-dervivatives. Douchi, which widely distributed throughout the country, is a traditional solid fermented soybean food with low nitrite content. In this study, bacterias which can degrade nitrite were isolated from Douchi and identified according to 16S rDNA sequence. Acinetobacter guillouiae, Acinetobacter bereziniae, Bacillus subtilis, Bacillus tequilensis, Bacillus amyloliquefaciens, Bacillus licheniformis, Bacillus aryabhattai and Bacillus methylotrophicus were selected. It was shown that all strains have nitrite degradation capability, in which 99.41 % nitrite can be degraded by Bacillus subtilis NDS1. The enzyme activities of these strains were determined at 24 h and 48 h, which corresponded to their nitrite degradation rates. The strains were firstly tried to inoculate in Jiangshui, which is a kind of traditional fermented vegetable in northwest China and often has high nitrite content. It was found that Bacillus subtilis NDS1, Bacillus tequilensis NDS3, Acinetobacter bereziniae NDS4, Bacillus subtilis NDS6, Bacillus subtilis NDS12 can degrade nitrite in Jiangshui more quickly, among which Acinetobacter bereziniae NDS4 degraded almost all nitrite in 48 h while it took 180 h for control. These results indicated that the selected strains have potential to become nitrite degradition agent in food. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
-
Rocha, Lidianne L; Colares, Geórgia B; Angelim, Alysson L; Grangeiro, Thalles B; Melo, Vânia M M
2013-11-15
This study evaluated the potential of bacterial isolates from mangrove sediments to degrade hexadecane, an paraffin hydrocarbon that is a large constituent of diesel and automobile lubricants. From a total of 18 oil-degrading isolates obtained by an enrichment technique, four isolates showed a great potential to degrade hexadecane. The strain MSIC01, which was identified by 16S rRNA gene sequencing as Acinetobacter sp., showed the best performance in degrading this hydrocarbon, being capable of completely degrading 1% (v/v) hexadecane within 48 h without releasing biosurfactants. Its hydrophobic surface probably justifies its potential to degrade high concentrations of hexadecane. Thus, the sediments from the studied mangrove harbour bacterial communities that are able to use oil as a carbon source, which is a particularly interesting feature due to the risk of oil spills in coastal areas. Moreover, Acinetobacter sp. MSIC01 emerged as a promising candidate for applications in bioremediation of contaminated mangrove sediments. Copyright © 2013 Elsevier Ltd. All rights reserved.
-
New strains of oil-degrading microorganisms for treating contaminated soils and wastes
NASA Astrophysics Data System (ADS)
Muratova, A. Yu; Panchenko, L. V.; Semina, D. V.; Golubev, S. N.; Turkovskaya, O. V.
2018-01-01
Two new strains Achromobacter marplatensis101n and Acinetobacter sp. S-33, capable of degrading 49 and 46% of oil within 7 days were isolated, identified, and characterized. The application of A. marplatensis 101n in combination with ammonium nitrate (100 mg·kg-1) for 30 days of cultivation resulted in the degradation of 49% of the initial total petroleum hydrocarbon content (274 g·kg-1) in the original highly acid (pH 4.9) oil-contaminated waste. Up to 30% of oil sludge added to a liquid mineral medium at a concentration of 15% was degraded after 10 days of cultivation of A. marplatensis 101n. Application of yellow alfalfa (Medicago falcata L.) plants with Acinetobacter sp. S-33 for bioremediation of oil-sludge-contaminated soil improved the quality of cleanup in comparison with the bacterium- or plant-only treatment. Inoculation of Acinetobacter sp. S-33 increased the growth of both roots and shoots by more than 40%, and positively influenced the soil microflora. We conclude that the new oil-degrading strains, Acinetobacter sp. S-33 and A. marplatensis 101n, can serve as the basis for new bioremediation agents for the treatment of oil contaminated soils and waste.
-
Antimicrobial active herbal compounds against Acinetobacter baumannii and other pathogens.
Tiwari, Vishvanath; Roy, Ranita; Tiwari, Monalisa
2015-01-01
Bacterial pathogens cause a number of lethal diseases. Opportunistic bacterial pathogens grouped into ESKAPE pathogens that are linked to the high degree of morbidity, mortality and increased costs as described by Infectious Disease Society of America. Acinetobacter baumannii is one of the ESKAPE pathogens which cause respiratory infection, pneumonia and urinary tract infections. The prevalence of this pathogen increases gradually in the clinical setup where it can grow on artificial surfaces, utilize ethanol as a carbon source and resists desiccation. Carbapenems, a β-lactam, are the most commonly prescribed drugs against A. baumannii. The high level of acquired and intrinsic carbapenem resistance mechanisms acquired by these bacteria makes their eradication difficult. The pharmaceutical industry has no solution to this problem. Hence, it is an urgent requirement to find a suitable alternative to carbapenem, a commonly prescribed drug for Acinetobacter infection. In order to do this, here we have made an effort to review the active compounds of plants that have potent antibacterial activity against many bacteria including carbapenem resistant strain of A. baumannii. We have also briefly highlighted the separation and identification methods used for these active compounds. This review will help researchers involved in the screening of herbal active compounds that might act as a replacement for carbapenem.
-
NASA Astrophysics Data System (ADS)
Mukherjee, Shraboni; Yadav, Vaibhav; Mondal, Madhumanti; Banerjee, Soumya; Halder, Gopinath
2017-07-01
The present study investigates the defluoridation capability of fluoride-resistant bacteria from contaminated groundwater collected from Asanjola and Madhabpur, West Bengal, India. Seven strains of fluoride-resistant bacteria were isolated employing culture media containing 10-250 mg/L of fluoride to evaluate their ability in reducing fluoride concentration in water. Five isolates exhibited significant amount of reduction in fluoride. Isolate RH5 achieved a maximum fluoride removal of 25.7 % from the media at 30 °C and pH 7 after 8 days of incubation. Based on morphological, physiological characteristics and analysis of 16S rDNA gene sequence, isolate RH5 was identified as Acinetobacter sp. RH5. Growth of RH5 was analysed at a diverse pH range, and it could thrive at pH 5-10. The present investigation revealed that the selective pressure of fluoride results in growth of fluoride-resistant bacteria capable of secreting high-affinity anion-binding compounds. This bacterium played a dominant bioremediative role by concentrating the anions so that they become less available. Hence, the fluoride-resistant bacteria, Acinetobacter sp. RH5, could be used as a promising strain for application in water defluoridation from contaminated sites.
-
Petersen, Kyle; Cannegieter, Suzanne C; van der Reijden, Tanny J; van Strijen, Beppie; You, David M; Babel, Britta S; Philip, Andrew I; Dijkshoorn, Lenie
2011-01-01
The epidemiology of Acinetobacter baumannii emerging in combat casualties is poorly understood. We analyzed 65 (54 nonreplicate) Acinetobacter isolates from 48 patients (46 hospitalized and 2 outpatient trainees entering the military) from October 2004 to October 2005 for genotypic similarities, time-space relatedness, and antibiotic susceptibility. Clinical and surveillance cultures were compared by amplified fragment length polymorphism (AFLP) genomic fingerprinting to each other and to strains of a reference database. Antibiotic susceptibility was determined, and multiplex PCR was performed for OXA-23-like, -24-like, -51-like, and -58-like carbapenemases. Records were reviewed for overlapping hospital stays of the most frequent genotypes, and risk ratios were calculated for any association of genotype with severity of Acute Physiology and Chronic Health Evaluation II (APACHE II) score or injury severity score (ISS) and previous antibiotic use. Nineteen genotypes were identified; two predominated, one consistent with an emerging novel international clone and the other unique to our database. Both predominant genotypes were carbapenem resistant, were present at another hospital before patients' admission to our facility, and were associated with higher APACHE II scores, higher ISSs, and previous carbapenem antibiotics in comparison with other genotypes. One predominated in wound and respiratory isolates, and the other predominated in wound and skin surveillance samples. Several other genotypes were identified as European clones I to III. Acinetobacter genotypes from recruits upon entry to the military, unlike those in hospitalized patients, did not include carbapenem-resistant genotypes. Acinetobacter species isolated from battlefield casualties are diverse, including genotypes belonging to European clones I to III. Two carbapenem-resistant genotypes were epidemic, one of which appeared to belong to a novel international clone.
-
Characterization and Evolution of Anthranilate 1,2-Dioxygenase from Acinetobacter sp. Strain ADP1
Eby, D. Matthew; Beharry, Zanna M.; Coulter, Eric D.; Kurtz, Donald M.; Neidle, Ellen L.
2001-01-01
The two-component anthranilate 1,2-dioxygenase of the bacterium Acinetobacter sp. strain ADP1 was expressed in Escherichia coli and purified to homogeneity. This enzyme converts anthranilate (2-aminobenzoate) to catechol with insertion of both atoms of O2 and consumption of one NADH. The terminal oxygenase component formed an α3β3 hexamer of 54- and 19-kDa subunits. Biochemical analyses demonstrated one Rieske-type [2Fe-2S] center and one mononuclear nonheme iron center in each large oxygenase subunit. The reductase component, which transfers electrons from NADH to the oxygenase component, was found to contain approximately one flavin adenine dinucleotide and one ferredoxin-type [2Fe-2S] center per 39-kDa monomer. Activities of the combined components were measured as rates and quantities of NADH oxidation, substrate disappearance, product appearance, and O2 consumption. Anthranilate conversion to catechol was stoichiometrically coupled to NADH oxidation and O2 consumption. The substrate analog benzoate was converted to a nonaromatic benzoate 1,2-diol with similarly tight coupling. This latter activity is identical to that of the related benzoate 1,2-dioxygenase. A variant anthranilate 1,2-dioxygenase, previously found to convey temperature sensitivity in vivo because of a methionine-to-lysine change in the large oxygenase subunit, was purified and characterized. The purified M43K variant, however, did not hydroxylate anthranilate or benzoate at either the permissive (23°C) or nonpermissive (39°C) growth temperatures. The wild-type anthranilate 1,2-dioxygenase did not efficiently hydroxylate methylated or halogenated benzoates, despite its sequence similarity to broad-substrate specific dioxygenases that do. Phylogenetic trees of the α and β subunits of these terminal dioxygenases that act on natural and xenobiotic substrates indicated that the subunits of each terminal oxygenase evolved from a common ancestral two-subunit component. PMID:11114907
-
CRISPR-cas subtype I-Fb in Acinetobacter baumannii: evolution and utilization for strain subtyping.
Karah, Nabil; Samuelsen, Ørjan; Zarrilli, Raffaele; Sahl, Jason W; Wai, Sun Nyunt; Uhlin, Bernt Eric
2015-01-01
Clustered regularly interspaced short palindromic repeats (CRISPR) are polymorphic elements found in the genome of some or all strains of particular bacterial species, providing them with a system of acquired immunity against invading bacteriophages and plasmids. Two CRISPR-Cas systems have been identified in Acinetobacter baumannii, an opportunistic pathogen with a remarkable capacity for clonal dissemination. In this study, we investigated the mode of evolution and diversity of spacers of the CRISPR-cas subtype I-Fb locus in a global collection of 76 isolates of A. baumannii obtained from 14 countries and 4 continents. The locus has basically evolved from a common ancestor following two main lineages and several pathways of vertical descent. However, this vertical passage has been interrupted by occasional events of horizontal transfer of the whole locus between distinct isolates. The isolates were assigned into 40 CRISPR-based sequence types (CST). CST1 and CST23-24 comprised 18 and 9 isolates, representing two main sub-clones of international clones CC1 and CC25, respectively. Epidemiological data showed that some of the CST1 isolates were acquired or imported from Iraq, where it has probably been endemic for more than one decade and occasionally been able to spread to USA, Canada, and Europe. CST23-24 has shown a remarkable ability to cause national outbreaks of infections in Sweden, Argentina, UAE, and USA. The three isolates of CST19 were independently imported from Thailand to Sweden and Norway, raising a concern about the prevalence of CST19 in Thailand. Our study highlights the dynamic nature of the CRISPR-cas subtype I-Fb locus in A. baumannii, and demonstrates the possibility of using a CRISPR-based approach for subtyping a significant part of the global population of A. baumannii.
-
CRISPR-cas Subtype I-Fb in Acinetobacter baumannii: Evolution and Utilization for Strain Subtyping
Karah, Nabil; Samuelsen, Ørjan; Zarrilli, Raffaele; Sahl, Jason W.; Wai, Sun Nyunt; Uhlin, Bernt Eric
2015-01-01
Clustered regularly interspaced short palindromic repeats (CRISPR) are polymorphic elements found in the genome of some or all strains of particular bacterial species, providing them with a system of acquired immunity against invading bacteriophages and plasmids. Two CRISPR-Cas systems have been identified in Acinetobacter baumannii, an opportunistic pathogen with a remarkable capacity for clonal dissemination. In this study, we investigated the mode of evolution and diversity of spacers of the CRISPR-cas subtype I-Fb locus in a global collection of 76 isolates of A. baumannii obtained from 14 countries and 4 continents. The locus has basically evolved from a common ancestor following two main lineages and several pathways of vertical descent. However, this vertical passage has been interrupted by occasional events of horizontal transfer of the whole locus between distinct isolates. The isolates were assigned into 40 CRISPR-based sequence types (CST). CST1 and CST23-24 comprised 18 and 9 isolates, representing two main sub-clones of international clones CC1 and CC25, respectively. Epidemiological data showed that some of the CST1 isolates were acquired or imported from Iraq, where it has probably been endemic for more than one decade and occasionally been able to spread to USA, Canada, and Europe. CST23-24 has shown a remarkable ability to cause national outbreaks of infections in Sweden, Argentina, UAE, and USA. The three isolates of CST19 were independently imported from Thailand to Sweden and Norway, raising a concern about the prevalence of CST19 in Thailand. Our study highlights the dynamic nature of the CRISPR-cas subtype I-Fb locus in A. baumannii, and demonstrates the possibility of using a CRISPR-based approach for subtyping a significant part of the global population of A. baumannii. PMID:25706932
-
Acinetobacter Peritoneal Dialysis Peritonitis: A Changing Landscape over Time
Chao, Chia-Ter; Lee, Szu-Ying; Yang, Wei-Shun; Chen, Huei-Wen; Fang, Cheng-Chung; Yen, Chung-Jen; Chiang, Chih-Kang; Hung, Kuan-Yu; Huang, Jenq-Wen
2014-01-01
Background Acinetobacter species are assuming an increasingly important role in modern medicine, with their persistent presence in health-care settings and antibiotic resistance. However, clinical reports addressing this issue in patients with peritoneal dialysis (PD) peritonitis are rare. Methods All PD peritonitis episodes caused by Acinetobacter that occurred between 1985 and 2012 at a single centre were retrospectively reviewed. Clinical features, microbiological data, and outcomes were analysed, with stratifications based upon temporal periods (before and after 2000). Results Acinetobacter species were responsible for 26 PD peritonitis episodes (3.5% of all episodes) in 25 patients. A. baumannii was the most common pathogen (54%), followed by A. iwoffii (35%), with the former being predominant after 2000. Significantly more episodes resulted from breaks in exchange sterility after 2000, while those from exit site infections decreased (P = 0.01). The interval between the last and current peritonitis episodes lengthened significantly after 2000 (5 vs. 13.6 months; P = 0.05). All the isolates were susceptible to cefepime, fluoroquinolone, and aminoglycosides, with a low ceftazidime resistance rate (16%). Nearly half of the patients (46%) required hospitalisation for their Acinetobacter PD-associated peritonitis, and 27% required an antibiotic switch. The overall outcome was fair, with no mortality and a 12% technique failure rate, without obvious interval differences. Conclusions The temporal change in the microbiology and origin of Acinetobacter PD-associated peritonitis in our cohort suggested an important evolutional trend. Appropriate measures, including technique re-education and sterility maintenance, should be taken to decrease the Acinetobacter peritonitis incidence in PD patients. PMID:25314341
-
Comparative genomics of multidrug resistance in Acinetobacter baumannii.
Fournier, Pierre-Edouard; Vallenet, David; Barbe, Valérie; Audic, Stéphane; Ogata, Hiroyuki; Poirel, Laurent; Richet, Hervé; Robert, Catherine; Mangenot, Sophie; Abergel, Chantal; Nordmann, Patrice; Weissenbach, Jean; Raoult, Didier; Claverie, Jean-Michel
2006-01-01
Acinetobacter baumannii is a species of nonfermentative gram-negative bacteria commonly found in water and soil. This organism was susceptible to most antibiotics in the 1970s. It has now become a major cause of hospital-acquired infections worldwide due to its remarkable propensity to rapidly acquire resistance determinants to a wide range of antibacterial agents. Here we use a comparative genomic approach to identify the complete repertoire of resistance genes exhibited by the multidrug-resistant A. baumannii strain AYE, which is epidemic in France, as well as to investigate the mechanisms of their acquisition by comparison with the fully susceptible A. baumannii strain SDF, which is associated with human body lice. The assembly of the whole shotgun genome sequences of the strains AYE and SDF gave an estimated size of 3.9 and 3.2 Mb, respectively. A. baumannii strain AYE exhibits an 86-kb genomic region termed a resistance island--the largest identified to date--in which 45 resistance genes are clustered. At the homologous location, the SDF strain exhibits a 20 kb-genomic island flanked by transposases but devoid of resistance markers. Such a switching genomic structure might be a hotspot that could explain the rapid acquisition of resistance markers under antimicrobial pressure. Sequence similarity and phylogenetic analyses confirm that most of the resistance genes found in the A. baumannii strain AYE have been recently acquired from bacteria of the genera Pseudomonas, Salmonella, or Escherichia. This study also resulted in the discovery of 19 new putative resistance genes. Whole-genome sequencing appears to be a fast and efficient approach to the exhaustive identification of resistance genes in epidemic infectious agents of clinical significance.
-
Boonyanugomol, Wongwarut; Kraisriwattana, Kairin; Rukseree, Kamolchanok; Boonsam, Kraisorn; Narachai, Panchaporn
In this study, we determined the antibacterial and synergistic activities of the essential oil from Zingiber cassumunar against the extensively drug-resistant (XDR) Acinetobacter baumannii strains. The antibacterial and synergistic properties of the essential oil from Z. cassumunar were examined by agar disc diffusion tests. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were evaluated by broth microdilution using the resazurin assay. The in vitro time-kill antibacterial kinetics was analyzed using the plate count technique. We found that the essential oil from Z. cassumunar had antibacterial activity against A. baumannii, with MIC and MBC ranging from 7.00 to 9.24mg/ml. The essential oil could completely inhibit A. baumannii at 1h, and coccoid-shaped bacteria were found after treatment. In addition, the essential oil had a synergistic effect when combined with antibiotics, e.g., aminoglycosides, fluoroquinolones, tetracyclines, and folate pathway inhibitors. Thus, the essential oil from Z. cassumunar has strong antibacterial and synergistic activities against XDR A. baumannii, which may provide the basis for the development of a new therapy against drug-resistant bacteria. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.
-
Isolation and identification of Acinetobacter spp. from healthy canine skin.
Mitchell, Kayleigh E; Turton, Jane F; Lloyd, David H
2018-06-01
Acinetobacter species can exhibit widespread resistance to antimicrobial agents. They are already recognized as important nosocomial pathogens of humans, but are becoming increasingly recognized in opportunistic infections of animals. This study aimed to determine whether Acinetobacter spp. are carried on skin of healthy dogs and, if present, to identify the species. Forty dogs were sampled at veterinary practices and rescue centres. They were free from skin disease and receiving no systemic or topical treatments. Skin swab samples were collected from four sites on each dog and cultured. Acinetobacter spp. isolates were detected by biochemical tests and gas chromatography. The species was determined by sequencing the RNA polymerase β-subunit (rpoB) gene. Isolates were screened for OXA carbapenemase genes and class 1 integrons capable of carrying resistance genes, and subjected to antimicrobial susceptibility tests. For 25% dogs sampled (10 of 40), Acinetobacter spp. were isolated at one or more skin sites. Thirteen Acinetobacter spp. isolates were recovered from 160 samples. The most frequently cultured was A. lwoffii (seven of 13), followed by A. baumannii (two of 13), A. junii (one of 13), A. calcoaceticus (one of 13), A. pittii (one of 13) and a novel Acinetobacter species (one of 13). Class 1 integrons and bla OXA -23-like were not detected. Isolates were susceptible to most antibiotics. The study confirms that Acinetobacter spp. can survive on canine skin, where they may be potential reservoirs for infection. This highlights the importance of good hygiene in veterinary practice, adhering to aseptic principles in surgery, and treatment based on culture and susceptibility testing where possible. © 2018 ESVD and ACVD.
-
Lee, Keyong Ho; Kim, Kye-Woong; Rhee, Ki-Hyeong
2010-12-01
The Actinomycete strain KH29 is antagonistic to the multidrug-resistant Acinetobacter baumannii. Based on the diaminopimelic acid (DAP) type, and the morphological and physiological characteristics observed through the use of scanning electron microscopy (SEM), KH29 was confirmed as belonging to the genus Streptomyces. By way of its noted 16S rDNA nucleotide sequences, KH29 was found to have a relationship with Streptomyces cinnamonensis. The production of an antibiotic from this strain was found to be most favorable when cultured with glucose, polypeptone, and yeast extract (PY) medium for 6 days at 27 degrees C. The antibiotic produced was identified, through comparisons with reported spectral data including MS and NMR as a cyclo(L-tryptophanyl-L-tryptophanyl). Cyclo(L-Trp-L-Trp), from the PY cultures of KH29, was seen to be highly effective against 41 of 49 multidrugresistant Acinetobacter baumannii. Furthermore, cyclo(LTrp- L-Trp) had antimicrobial activity against Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus, Saccharomyces cerevisiae, Aspergillus niger, and Candida albicans, However, it was ineffective against Streptomyces murinus.
-
Michiel, Magalie; Perchat, Nadia; Perret, Alain; Tricot, Sabine; Papeil, Aude; Besnard, Marielle; de Berardinis, Véronique; Salanoubat, Marcel; Fischer, Cécile
2012-12-01
In aerobic cells, urate is oxidized to 5-hydroxyisourate by two distinct enzymes: a coenzyme-independent urate oxidase (EC 1.7.3.3) found in eukaryotes and bacteria like Bacillus subtilis and a prokaryotic flavoprotein urate hydroxylase (HpxO) originally found in some Klebsiella species. More cases of analogous or non-homologous isofunctional enzymes (NISE) for urate catabolism have been hypothesized by inspecting bacterial genomes. Here, we used a functional complementation approach in which a candidate gene for urate oxidation is integrated by homologous recombination in the Acinetobacter baylyi ADP1 genome at the locus of its original hpxO gene. Catabolism of urate was restored in A. baylyi ADP1 expressing a FAD-dependent protein from Xanthomonas campestris, representing a new urate hydroxylase family that we called HpyO. This enzyme was kinetically characterized and compared with other HpxO enzymes. In contrast to the latter, HpyO is a typical Michaelian enzyme. This work provides the first experimental evidences for the function of HpyO in bacterial urate catabolism and establishes it as a NISE of HpxO. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.
-
Bertram, Jonathan H.; Mulliner, Kalene M.; Shi, Ke; Plunkett, Mary H.; Nixon, Peter; Serratore, Nicholas A.; Douglas, Christopher J.; Aihara, Hideki
2017-01-01
ABSTRACT Enzymes involved in lipid biosynthesis and metabolism play an important role in energy conversion and storage and in the function of structural components such as cell membranes. The fatty aldehyde dehydrogenase (FAldDH) plays a central function in the metabolism of lipid intermediates, oxidizing fatty aldehydes to the corresponding fatty acid and competing with pathways that would further reduce the fatty aldehydes to fatty alcohols or require the fatty aldehydes to produce alkanes. In this report, the genes for four putative FAldDH enzymes from Marinobacter aquaeolei VT8 and an additional enzyme from Acinetobacter baylyi were heterologously expressed in Escherichia coli and shown to display FAldDH activity. Five enzymes (Maqu_0438, Maqu_3316, Maqu_3410, Maqu_3572, and the enzyme reported under RefSeq accession no. WP_004927398) were found to act on aldehydes ranging from acetaldehyde to hexadecanal and also acted on the unsaturated long-chain palmitoleyl and oleyl aldehydes. A comparison of the specificities of these enzymes with various aldehydes is presented. Crystallization trials yielded diffraction-quality crystals of one particular FAldDH (Maqu_3316) from M. aquaeolei VT8. Crystals were independently treated with both the NAD+ cofactor and the aldehyde substrate decanal, revealing specific details of the likely substrate binding pocket for this class of enzymes. A likely model for how catalysis by the enzyme is accomplished is also provided. IMPORTANCE This study provides a comparison of multiple enzymes with the ability to oxidize fatty aldehydes to fatty acids and provides a likely picture of how the fatty aldehyde and NAD+ are bound to the enzyme to facilitate catalysis. Based on the information obtained from this structural analysis and comparisons of specificities for the five enzymes that were characterized, correlations to the potential roles played by specific residues within the structure may be drawn. PMID:28389542
-
Nature, nomenclature and taxonomy of obligate methanol utilizing strains.
Cercel, M
1999-01-01
In a screening program, a number of different bacterial strains with the ability to utilize methanol as a sole carbon and energy source were isolated and described. They are well known methanol utilizing genera Pseudomonas, Klebsiella, Micrococcus, Methylomonas or, on the contrary, the new, unknown genera and species of methylotrophic bacteria. In the last category, Acinetobacter and Alcaligenes are the new reported genera of organisms able to use methanol as a sole carbon and energy source. The present paper reports the very complex physiological and biochemical modifications when very versatile bacteria such as Pseudomonas aeruginosa and Acinetobacter calcoaceticus are cultured on methanol and when the obligate methylotrophic state is compared with the facultative methylotrophic state of the same bacterial strain. Based on experiments and comparisons with literature data, it seems that Methylomonas methanica is the obligate methylotrophic state of Pseudomonas aeruginosa and that Acinetobacter calcoaceticus is the facultative methylotrophic state of Methylococcus capsulatus, an obligate methylotroph. The relationship of the obligate to the facultative and of the facultative to the obligate methylotrophy were established. These new methylotrophic genera and species, the profound physiological and biochemical modifications as well as the new data concerning nature, nomenclature and taxonomy of methanol utilizing bateria were reported for the first time in 1983.
-
Tani, Akio; Sakai, Yasuyoshi; Ishige, Takeru; Kato, Nobuo
2000-01-01
NADPH-dependent alkylaldehyde reducing enzyme, which was greatly induced by n-hexadecane, from Acinetobacter sp. strain M-1 was purified and characterized. The purified enzyme had molecular masses of 40 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 160 kDa as determined by gel filtration chromatography. The enzyme, which was shown to be highly thermostable, was most active toward n-heptanal and could use n-alkylaldehydes ranging from C2 to C14 and several substituted benzaldehydes, including the industrially important compounds cinnamyl aldehyde and anisaldehyde, as substrates. The alrA gene coding for this enzyme was cloned, and its nucleotide sequence was determined. The deduced amino acid sequence encoded by the alrA gene exhibited homology to the amino acid sequences of zinc-containing alcohol dehydrogenases from various sources. The gene could be highly expressed in Escherichia coli, and the product was purified to homogeneity by simpler procedures from the recombinant than from the original host. Our results show that this enzyme can be used for industrial bioconversion of useful alcohols and aldehydes. PMID:11097895
-
2009-06-01
marcescens . Appl. Environ. Microbiol. 73:2199– 2206. 12. Turton, J. F., N. Woodford, J. Glover, S . Yarde, M. E. Kaufmann, and T. L. Pitt. 2006...Susceptibility Testing and Resistance Genes in Isolates of Acinetobacter baumannii-Acinetobacter calcoaceticus Complex from a U.S. Military Hospital Kevin S ...3 2 8 29 9 30 7 a S , susceptible. 2693 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of
-
La Scola, B; Fournier, P E; Brouqui, P; Raoult, D
2001-05-01
As part of a survey for trench fever among homeless people in Marseilles, France, we attempted isolation of Bartonella quintana from body lice. A decontamination protocol of immersion in 70% ethanol with 0.2% iodine was devised and was tested with a laboratory colony of body lice. Lice which had been experimentally contaminated with either Escherichia coli, Staphylococcus epidermidis, or Acinetobacter spp. were successfully decontaminated, and this process did not prevent the culture of B. quintana from these lice. One hundred sixty-one lice obtained from homeless patients were studied by the protocol. B. quintana was isolated on axenic medium from 15 of 161 body lice and was detected in 41 of 161 lice by PCR. Acinetobacter spp. and Serratia marcescens were also isolated from body lice. The sensitivities of PCR and culture of B. quintana were 98 and 36%, respectively. These procedures may be useful for epidemiologic studies of trench fever and for the recovery of strains for characterization and comparison.
-
Biodegradation of long-chain n-paraffins from waste oil of car engine by Acinetobacter sp.
Koma, D; Hasumi, F; Yamamoto, E; Ohta, T; Chung, S Y; Kubo, M
2001-01-01
Microorganisms that degrade long-chain n-paraffins from used car engine oil were isolated from soil. For the screening, a fraction of n-paraffin prepared from car engine oil was applied as the sole carbon source. The strain was identified as Acinetobacter sp. The ability of the strain to assimilate long-chain n-paraffins was assessed and characterized. The strain mineralized long-chain n-paraffins (0.1% w/v) in the minimal medium after cultivation for 96 h and also reduced the weight of the waste oil added (1% w/v) by 20% after 72 h without an extracellular biosurfactant. When n-hexadecane was fed as substrate, 1-hexadecanol and 1-hexadecanoic acid were detected as the intermediates by gas chromatography/mass spectrometry. This indicates that the long-chain n-paraffins were metabolized via the terminal oxidation pathway of n-alkane.
-
Pimchan, T; Maensiri, D; Eumkeb, G
2017-10-01
To address the resistance of Acinetobacter baumannii to β-lactam antibiotics, combination therapy between different antibiotic classes is increasingly used. The antibacterial activity of α-mangostin (AMT) alone or in combination with ceftazidime (CTZ) was investigated against ceftazidime-resistant A. baumannii DMST 45378 (CRAB). Initial screening showed that A. baumannii strains possessed AmpC β-lactamase (AmpC), extended-spectrum beta-lactamase (ESBL) and metallo-β-lactamases (MBL). Minimum inhibitory concentrations (MICs) of all test agents were >800 μg ml -1 against CRAB. The combination of AMT/CTZ exhibited a fractional inhibitory concentration index (FICI) of <0·35 suggestive of synergy. Time-kill curves showed that the AMT/CTZ combination was significantly more efficient (P < 0·01) at reducing CRAB than the individual components. Structural analysis revealed that AMT/CTZ-treated cells exhibited increased cell volume, increased cytoplasmic and outer membrane permeability and a decrease in outer membrane peptidoglycan-associated protein (OMPG) bands. In addition, it was shown that Type IV β-lactamase was inhibited by AMT. The data suggest that AMT in combination with CTZ is synergistic and efficient against CRAB. The data also indicate that the AMT/CTZ combination may target multiple structures on the bacterial cell surface. This represents the first report of this effect on CRAB and could potentially be expanded into in vivo studies. Significance and Impact of the Study: Acinetobacter baumannii strains cause serious infections, patient mortality, and have been reported to rise of multidrug resistance. This article represents the first report of using α-mangostin plus ceftazidime against these resistant strains and its mechanism of action. α-mangostin has no cytotoxic effects. Therefore, α-mangostin has strong potential for development as a useful, novel adjunct phytopharmaceutical to ceftazidime synergistically for the treatment of these strains
-
García-Quintanilla, Meritxell; Carretero-Ledesma, Marta; Moreno-Martínez, Patricia; Martín-Peña, Reyes; Pachón, Jerónimo; McConnell, Michael J
2015-12-01
Treatment options for multidrug-resistant (MDR) strains of Acinetobacter baumannii that acquire resistance to colistin are limited. Acinetobacter baumannii can become highly resistant to colistin through complete loss of lipopolysaccharide (LPS) owing to mutations in the genes encoding the first three enzymes involved in lipid A biosynthesis (lpxA, lpxC and lpxD). The objective of this study was to characterise the susceptibility to 15 clinically relevant antibiotics and 6 antimicrobial peptides (AMPs) of MDR A. baumannii clinical isolates that acquired colistin resistance due to mutations in lpxA, lpxC and lpxD as well as their colistin-susceptible counterparts. A dramatic increase in antibiotic susceptibility (≥16-fold increase) was observed upon LPS loss for azithromycin, rifampicin and vancomycin, whereas a moderate increase in susceptibility was seen for amikacin, ceftazidime, imipenem, cefepime and meropenem. Importantly, concentrations ranging from 8 mg/L to 32 mg/L of the six AMPs were able to reduce bacterial viability by ≥3 log10 in growth curve assays. We also demonstrate that colistin resistance results in partial colistin dependence for growth in LPS-deficient strains containing mutations in lpxA, lpxC and lpxD, but not when colistin resistance occurs via LPS modification due to mutations in the PmrA/B two-component system. The results of this study indicate that loss of LPS expression results in collateral sensitivity to azithromycin, rifampicin and vancomycin, and that the six AMPs tested retain activity against LPS-deficient strains, indicating that these antibiotics may be viable treatment options for infections caused by these strains. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.
-
Collier, Lauren S.; Gaines, George L.; Neidle, Ellen L.
1998-01-01
In Acinetobacter sp. strain ADP1, benzoate degradation requires the ben genes for converting benzoate to catechol and the cat genes for degrading catechol. Here we describe a novel transcriptional activator, BenM, that regulates the chromosomal ben and cat genes. BenM is homologous to CatM, a LysR-type transcriptional activator of the cat genes. Unusual regulatory features of this system include the abilities of both BenM and CatM to recognize the same inducer, cis,cis-muconate, and to regulate some of the same genes, such as catA and catB. Unlike CatM, BenM responded to benzoate. Benzoate together with cis,cis-muconate increased the BenM-dependent expression of the benABCDE operon synergistically. CatM was not required for this synergism, nor did CatM regulate the expression of a chromosomal benA::lacZ transcriptional fusion. BenM-mediated regulation differs significantly from that of the TOL plasmid-encoded conversion of benzoate to catechol in pseudomonads. The benM gene is immediately upstream of, and divergently transcribed from, benA, and a possible DNA binding site for BenM was identified between the two coding regions. Two mutations in the predicted operator/promoter region rendered ben gene expression either constitutive or inducible by cis,cis-muconate but not benzoate. Mutants lacking BenM, CatM, or both of these regulators degraded aromatic compounds at different rates, and the levels of intermediary metabolites that accumulated depended on the genetic background. These studies indicated that BenM is necessary for ben gene expression but not for expression of the cat genes, which can be regulated by CatM. In a catM-disrupted strain, BenM was able to induce higher levels of catA expression than catB expression. PMID:9573203
-
In vitro synergistic activity of tigecycline and colistin against XDR-Acinetobacter baumannii.
Dizbay, Murat; Tozlu, Derya Keten; Cirak, Meltem Yalinay; Isik, Yasemin; Ozdemir, Kevser; Arman, Dilek
2010-02-01
The emergence of extensive drug-resistant (XDR) Acinetobacter baumannii limits the therapeutic options and leads to high mortality in intensive care units. Combined antibiotic therapy is frequently recommended for the treatment of these infections. Colistin (CO) and tigecycline (TIG), alone or in combination with other antimicrobials, are the most commonly used antibiotics in the treatment of these resistant infections. In this study, the in vitro synergistic activity of TIG and CO were tested for 25 XDR-A. baumannii strains isolated from ventilator-associated pneumonia by the Etest method. Resistance to CO was not detected, whereas 8% of the strains were resistant to TIG. The TIG-CO combination was more synergistic than TIG-rifampin and CO-rifampin according to the fractional inhibitory concentration index. No antagonism was detected between the drugs in the study. There was no strong correlation between the activity of the combinations with reference to strains or genotypes. Our results suggest that the combined use of TIG and CO may be useful for the treatment of XDR-A. baumannii infections.
-
Al Atrouni, Ahmad; Hamze, Monzer; Jisr, Tamima; Lemarié, Carole; Eveillard, Matthieu; Joly-Guillou, Marie-Laure; Kempf, Marie
2016-11-01
To investigate the molecular epidemiology of Acinetobacter baumannii strains isolated from different hospitals in Lebanon. A total of 119 non-duplicate Acinetobacter strains were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and partial rpoB gene sequencing. Antibiotic susceptibility testing was performed by disc diffusion method and all identified carbapenem-resistant isolates were investigated by PCR assays for the presence of the carbapenemase-encoding genes. Multilocus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) were used for molecular typing. Of the 119 A. baumannii isolates, 76.5% were resistant to carbapenems. The most common carbapenemase was the OXA-23-type, found in 82 isolates. The study of population structure using MLST revealed the presence of 30 sequence types (STs) including 18 new ones, with ST2 being the most commonly detected, accounting for 61% of the isolates typed. PFGE performed on all strains of ST2 identified a major cluster of 53 isolates, in addition to three other minor clusters and ten unique profiles. This study highlights the wide dissemination of highly related OXA-23-producing carbapenem-resistant A. baumannii belonging to the international clone II in Lebanon. Thus, appropriate infection control measures are recommended in order to control the geographical spread of this clone in this country. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.
-
Gaddy, Jennifer A.; Arivett, Brock A.; McConnell, Michael J.; López-Rojas, Rafael; Pachón, Jerónimo
2012-01-01
Acinetobacter baumannii, which causes serious infections in immunocompromised patients, expresses high-affinity iron acquisition functions needed for growth under iron-limiting laboratory conditions. In this study, we determined that the initial interaction of the ATCC 19606T type strain with A549 human alveolar epithelial cells is independent of the production of BasD and BauA, proteins needed for acinetobactin biosynthesis and transport, respectively. In contrast, these proteins are required for this strain to persist within epithelial cells and cause their apoptotic death. Infection assays using Galleria mellonella larvae showed that impairment of acinetobactin biosynthesis and transport functions significantly reduces the ability of ATCC 19606T cells to persist and kill this host, a defect that was corrected by adding inorganic iron to the inocula. The results obtained with these ex vivo and in vivo approaches were validated using a mouse sepsis model, which showed that expression of the acinetobactin-mediated iron acquisition system is critical for ATCC 19606T to establish an infection and kill this vertebrate host. These observations demonstrate that the virulence of the ATCC 19606T strain depends on the expression of a fully active acinetobactin-mediated system. Interestingly, the three models also showed that impairment of BasD production results in an intermediate virulence phenotype compared to those of the parental strain and the BauA mutant. This observation suggests that acinetobactin intermediates or precursors play a virulence role, although their contribution to iron acquisition is less relevant than that of mature acinetobactin. PMID:22232188
-
Annual Surveillance Summary: Acinetobacter Infections in the Military Health System, 2015
2017-05-01
pharmacy data to assess prescription practices, the Standard Inpatient Data Record to determine healthcare-associated exposures, Defense Manpower ...7 Results ...System (CHCS) microbiology data were used to identify positive Acinetobacter species laboratory results . A unique Acinetobacter species infection
-
Lai, Juo-Hsin; Yang, Jhih-Tian; Chern, Jeffy; Chen, Te-Li; Wu, Wan-Ling; Liao, Jiahn-Haur; Tsai, Shih-Feng; Liang, Suh-Yuen; Chou, Chi-Chi
2016-01-01
Nosocomial infectious outbreaks caused by multidrug-resistant Acinetobacter baumannii have emerged as a serious threat to human health. Phosphoproteomics of pathogenic bacteria has been used to identify the mechanisms of bacterial virulence and antimicrobial resistance. In this study, we used a shotgun strategy combined with high-accuracy mass spectrometry to analyze the phosphoproteomics of the imipenem-susceptible strain SK17-S and -resistant strain SK17-R. We identified 410 phosphosites on 248 unique phosphoproteins in SK17-S and 285 phosphosites on 211 unique phosphoproteins in SK17-R. The distributions of the Ser/Thr/Tyr/Asp/His phosphosites in SK17-S and SK17-R were 47.0%/27.6%/12.4%/8.0%/4.9% versus 41.4%/29.5%/17.5%/6.7%/4.9%, respectively. The Ser-90 phosphosite, located on the catalytic motif S88VS90K of the AmpC β-lactamase, was first identified in SK17-S. Based on site-directed mutagenesis, the nonphosphorylatable mutant S90A was found to be more resistant to imipenem, whereas the phosphorylation-simulated mutant S90D was sensitive to imipenem. Additionally, the S90A mutant protein exhibited higher β-lactamase activity and conferred greater bacterial protection against imipenem in SK17-S compared with the wild-type. In sum, our results revealed that in A. baumannii, Ser-90 phosphorylation of AmpC negatively regulates both β-lactamase activity and the ability to counteract the antibiotic effects of imipenem. These findings highlight the impact of phosphorylation-mediated regulation in antibiotic-resistant bacteria on future drug design and new therapies. PMID:26499836
-
Pérez, A.; Merino, M.; Rumbo-Feal, S.; Álvarez-Fraga, L.; Vallejo, J. A.; Beceiro, A.; Ohneck, E. J.; Mateos, J.; Fernández-Puente, P.; Actis, L. A.; Poza, M.; Bou, G.
2017-01-01
ABSTRACT Acinetobacter baumannii is a hospital-acquired pathogen that shows an extraordinary capacity to stay in the hospital environment. Adherence of the bacteria to eukaryotic cells or to abiotic surfaces is the first step for establishing an infection. The A. baumannii strain AbH12O-A2 showed an exceptional ability to adhere to A549 epithelial cells. The AbFhaB/FhaC 2-partner secretion (TPS) system involved in adhesion was discovered after the screening of the recently determined A. baumannii AbH12O-A2 strain genome (CP009534.1). The AbFhaB is a large exoprotein which transport to the bacterial surface is mediated by the AbFhaC protein. In the present study, the role of this TPS system in the AbH12O-A2 adherence phenotype was investigated. The functional inactivation of this 2-partner secretion system was addressed by analyzing the outer membrane vesicles (OMV) proteomic profile from the wild-type strain and its derivative mutant AbH12O-A2ΔfhaC demonstrating that AbFhaB is no longer detected in the absence of AbFhaC. Scanning electron microscopy (SEM) and adhesion experiments demonstrated that inactivation of the AbFhaB/FhaC system significantly decreases bacterial attachment to A549 alveolar epithelial cells. Moreover, it has been demonstrated that this 2-partner secretion system is involved in fibronectin-mediated adherence of the A. baumannii AbH12O-A2 isolate. Finally, we report that the AbFhaB/FhaC system is involved in virulence when tested using invertebrate and vertebrate hosts. These data suggest the potential role that this AbFhaB/FhaC secretion system could play in the pathobiology of A. baumannii. PMID:27858524
-
Pérez, A; Merino, M; Rumbo-Feal, S; Álvarez-Fraga, L; Vallejo, J A; Beceiro, A; Ohneck, E J; Mateos, J; Fernández-Puente, P; Actis, L A; Poza, M; Bou, G
2017-08-18
Acinetobacter baumannii is a hospital-acquired pathogen that shows an extraordinary capacity to stay in the hospital environment. Adherence of the bacteria to eukaryotic cells or to abiotic surfaces is the first step for establishing an infection. The A. baumannii strain AbH12O-A2 showed an exceptional ability to adhere to A549 epithelial cells. The AbFhaB/FhaC 2-partner secretion (TPS) system involved in adhesion was discovered after the screening of the recently determined A. baumannii AbH12O-A2 strain genome (CP009534.1). The AbFhaB is a large exoprotein which transport to the bacterial surface is mediated by the AbFhaC protein. In the present study, the role of this TPS system in the AbH12O-A2 adherence phenotype was investigated. The functional inactivation of this 2-partner secretion system was addressed by analyzing the outer membrane vesicles (OMV) proteomic profile from the wild-type strain and its derivative mutant AbH12O-A2ΔfhaC demonstrating that AbFhaB is no longer detected in the absence of AbFhaC. Scanning electron microscopy (SEM) and adhesion experiments demonstrated that inactivation of the AbFhaB/FhaC system significantly decreases bacterial attachment to A549 alveolar epithelial cells. Moreover, it has been demonstrated that this 2-partner secretion system is involved in fibronectin-mediated adherence of the A. baumannii AbH12O-A2 isolate. Finally, we report that the AbFhaB/FhaC system is involved in virulence when tested using invertebrate and vertebrate hosts. These data suggest the potential role that this AbFhaB/FhaC secretion system could play in the pathobiology of A. baumannii.
-
Balseiro-Romero, María; Gkorezis, Panagiotis; Kidd, Petra S; Van Hamme, Jonathan; Weyens, Nele; Monterroso, Carmen; Vangronsveld, Jaco
2017-10-03
Bioremediation of polluted soils is a promising technique with low environmental impact, which uses soil organisms to degrade soil contaminants. In this study, 19 bacterial strains isolated from a diesel-contaminated soil were screened for their diesel-degrading potential, biosurfactant (BS) production, and biofilm formation abilities, all desirable characteristics when selecting strains for re-inoculation into hydrocarbon-contaminated soils. Diesel-degradation rates were determined in vitro in minimal medium with diesel as the sole carbon source. The capacity to degrade diesel range organics (DROs) of strains SPG23 (Arthobacter sp.) and PF1 (Acinetobacter oleivorans) reached 17-26% of total DROs after 10 days, and 90% for strain GK2 (Acinetobacter calcoaceticus). The amount and rate of alkane degradation decreased significantly with increasing carbon number for strains SPG23 and PF1. Strain GK2, which produced BSs and biofilms, exhibited a greater extent, and faster rate of alkane degradation compared to SPG23 and PF1. Based on the outcomes of degradation experiments, in addition to BS production, biofilm formation capacities, and previous genome characterizations, strain GK2 is a promising candidate for microbial-assisted phytoremediation of diesel-contaminated soils. These results are of particular interest to select suitable strains for bioremediation, not only presenting high diesel-degradation rates, but also other characteristics which could improve rhizosphere colonization.
-
Vila-Farrés, Xavier; Ferrer-Navarro, Mario; Callarisa, Anna Elena; Martí, Sara; Espinal, Paula; Gupta, Sushim; Rolain, Jean-Marc; Giralt, Ernest; Vila, Jordi
2015-11-01
Acinetobacter nosocomialis has increasingly been reported as an opportunistic pathogen causing nosocomial infections. Although it is more susceptible to all antimicrobial agents than Acinetobacter baumannii, MDR clinical isolates have also been described. In addition, several studies have shown a high percentage of resistance to colistin. Therefore, in the present study we investigated the mechanism of resistance to colistin in this microorganism. Colistin-resistant strains were selected from the original colistin-susceptible A. nosocomialis strain following multi-step mutant selection. Comparative genomic and proteomic analyses of both colistin-susceptible and colistin-resistant A. nosocomialis strains were performed. In addition, virulence was investigated using the Caenorhabditis elegans assay. The colistin-resistant mutants selected showed a lower resistance profile for other types of antibacterial agents together with a significant decrease in virulence. The LT50 (i.e. time required to kill 50% of the nematodes) for the colistin-susceptible strain (WT) was 7 days compared with 9 days for the colistin-resistant strain (256) (P < 0.0001). In the genomic studies, several mutations were observed in the lpxD genes, leading to the loss of LPS in the colistin-resistant strains. The proteomic studies showed several up- and down-regulated proteins that may be involved in colistin resistance or in a decrease in the resistance profile for several antibiotics. This study shows that the mechanism of resistance to colistin by A. nosocomialis is mainly associated with the loss of LPS due to mutations in the lpxD gene, although changes in the expression of some proteins cannot be ruled out. In addition, the acquisition of colistin resistance is related to a decrease in virulence. © The Author 2015. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
-
Accelerating pathway evolution by increasing the gene dosage of chromosomal segments.
Tumen-Velasquez, Melissa; Johnson, Christopher W; Ahmed, Alaa; Dominick, Graham; Fulk, Emily M; Khanna, Payal; Lee, Sarah A; Schmidt, Alicia L; Linger, Jeffrey G; Eiteman, Mark A; Beckham, Gregg T; Neidle, Ellen L
2018-06-18
Experimental evolution is a critical tool in many disciplines, including metabolic engineering and synthetic biology. However, current methods rely on the chance occurrence of a key step that can dramatically accelerate evolution in natural systems, namely increased gene dosage. Our studies sought to induce the targeted amplification of chromosomal segments to facilitate rapid evolution. Since increased gene dosage confers novel phenotypes and genetic redundancy, we developed a method, Evolution by Amplification and Synthetic Biology (EASy), to create tandem arrays of chromosomal regions. In Acinetobacter baylyi , EASy was demonstrated on an important bioenergy problem, the catabolism of lignin-derived aromatic compounds. The initial focus on guaiacol (2-methoxyphenol), a common lignin degradation product, led to the discovery of Amycolatopsis genes ( gcoAB ) encoding a cytochrome P450 enzyme that converts guaiacol to catechol. However, chromosomal integration of gcoAB in Pseudomonas putida or A. baylyi did not enable guaiacol to be used as the sole carbon source despite catechol being a growth substrate. In ∼1,000 generations, EASy yielded alleles that in single chromosomal copy confer growth on guaiacol. Different variants emerged, including fusions between GcoA and CatA (catechol 1,2-dioxygenase). This study illustrates the power of harnessing chromosomal gene amplification to accelerate the evolution of desirable traits.
-
Wang, HaiKuan; Zhang, Jie; Wang, XiaoJie; Qi, Wei; Dai, YuJie
2012-01-01
The production of a low-temperature alkalophilic lipase from Acinetobacter johnsonii was improved using genome shuffling. The starting populations, obtained by UV irradiation and diethyl sulfate mutagenesis, were subjected to recursive protoplast fusion. The optimal conditions for protoplast formation and regeneration were 0.15 mg lysozyme/ml for 45 min at 37°C. The protoplasts were inactivated under UV for 20 min or heated at 60°C for 60 min and a fusant probability of ~98% was observed. The positive colonies were created by fusing the inactivated protoplasts. After two rounds of genome shuffling, one strain, F22, with a lipase activity of 7 U/ml was obtained.
-
Harms, Klaus; Lunnan, Asbjørn; Hülter, Nils; Mourier, Tobias; Vinner, Lasse; Andam, Cheryl P.; Marttinen, Pekka; Fridholm, Helena; Hansen, Anders Johannes; Hanage, William P.; Nielsen, Kaare Magne; Willerslev, Eske; Johnsen, Pål Jarle
2016-01-01
In a screen for unexplained mutation events we identified a previously unrecognized mechanism generating clustered DNA polymorphisms such as microindels and cumulative SNPs. The mechanism, short-patch double illegitimate recombination (SPDIR), facilitates short single-stranded DNA molecules to invade and replace genomic DNA through two joint illegitimate recombination events. SPDIR is controlled by key components of the cellular genome maintenance machinery in the gram-negative bacterium Acinetobacter baylyi. The source DNA is primarily intragenomic but can also be acquired through horizontal gene transfer. The DNA replacements are nonreciprocal and locus independent. Bioinformatic approaches reveal occurrence of SPDIR events in the gram-positive human pathogen Streptococcus pneumoniae and in the human genome. PMID:27956618
-
Identification and characterisation of potential biofertilizer bacterial strains
NASA Astrophysics Data System (ADS)
Karagöz, Kenan; Kotan, Recep; Dadaşoǧlu, Fatih; Dadaşoǧlu, Esin
2016-04-01
In this study we aimed that isolation, identification and characterizations of PGPR strains from rhizosphere of legume plants. 188 bacterial strains isolated from different legume plants like clover, sainfoin and vetch in Erzurum province of Turkey. These three plants are cultivated commonly in the Erzurum province. It was screen that 50 out of 188 strains can fix nitrogen and solubilize phosphate. These strains were identified via MIS (Microbial identification system). According to MIS identification results, 40 out of 50 strains were identified as Bacillus, 5 as Pseudomonas, 3 as Paenibacillus, 1 as Acinetobacter, 1 as Brevibacterium. According to classical test results, while the catalase test result of all isolates are positive, oxidase, KOH and starch hydrolysis rest results are variable.
-
USDA-ARS?s Scientific Manuscript database
Acinetobacter baumannii-calcoaceticus complex (ABC) infections have complicated the care of U.S. combat casualties. In this study, 102 ABC isolates from wounded soldiers treated at National Naval Medical Center (NNMC) were characterized by phenotype and genotype to identify clones in this population...
-
Yu, Kyung Ok; Jung, Ju; Kim, Seung Wook; Park, Chul Hwan; Han, Sung Ok
2012-01-01
The high price of petroleum-based diesel fuel has led to the development of alternative fuels, such as ethanol. Saccharomyces cerevisiae was metabolically engineered to utilize glycerol as a substrate for ethanol production. For the synthesis of fatty acid ethyl esters (FAEEs) by engineered S. cerevisiae that utilize glycerol as substrate, heterologous expression of an unspecific acyltransferase from Acinetobacter baylyi with glycerol utilizing genes was established. As a result, the engineered YPH499 (pGcyaDak, pGupWs-DgaTCas) strain produced 0.24 g/L FAEEs using endogenous ethanol produced from glycerol. And this study also demonstrated the possibility of increasing FAEE production by enhancing ethanol production by minimizing the synthesis of glycerol. The overall FAEE production in strain YPH499 fps1Δ gpd2Δ (pGcyaDak, pGupWs-DgaTCas) was 2.1-fold more than in YPH499 (pGcyaDak, pGupWs-DgaTCas), with approximately 0.52 g/L FAEEs produced, while nearly 17 g/L of glycerol was consumed. These results clearly indicated that FAEEs were synthesized in engineered S. cerevisiae by esterifying exogenous fatty acids with endogenously produced ethanol from glycerol. This microbial system acts as a platform in applying metabolic engineering that allows the production of FAEEs from cheap and abundant substrates specifically glycerol through the use of endogenous bioethanol. Copyright © 2011 Wiley Periodicals, Inc.
-
Saha, Sahadev Chandra; Chopade, Balu Anand
2009-08-01
In recent years, interest has been growing to preserve food including meat applying gamma radiation recommended by International Atomic Energy Agency to extend the shelf-life of meat retaining the organoleptic conditions as it is. In view of this point the present study aims to check the sensitivity of Acinetobacter spp. isolated from meat to gamma radiations. Seven species of Acinetobacter viz. A. lwoffli M1; A. baumannii M8; A. calcoaceticus M19; A. junii M20; A. johnsonnii M23; A. haemolyticus M27 and A. radioresistens M25 isolated from meat were exposed to gamma radiation at the dose level of 0.1 to 10 KGy. The D10 value of Acinetobacter was found highest 1.25 KGy in A. radioresistens M25, which was 4 to 8 times higher than other genospecies of Acinetobacter. Acinetobacter radioresistens M25 contains one plasmid of 45 Kb. The radicidation dose of 4 KGy gamma radiations was found to be sufficient to eliminate the natural contamination of meat and contamination by Acinetobacter. To eliminate radiation resistant Acinetobacter contamination a dose of 4 to 5 KGy was required. Development of the radicidation process for preservation of meat to eliminate Acinetobacter as contaminants at low temperature is one of the new and interesting phenomena. Attempts of finding the appropriate radicidation dose for preservation of meat at low temperature will open up new avenues for commercial preservation of meat.
-
Su, Jun Feng; Ma, Min; Wei, Li; Ma, Fang; Lu, Jin Suo; Shao, Si Cheng
2016-06-15
Acinetobacter sp. J25 exhibited good denitrification and high algicidal activity against toxic Microcystis aeruginosa. Response surface methodology (RSM) experiments showed that the maximum algicidal ratio occurred under the following conditions: temperature, 30.46°C; M. aeruginosa density, 960,000cellsmL(-1); and inoculum, 23.75% (v/v). Of these, inoculum produced the maximum effect. In the eutrophic landscape water experiment, 10% bacterial culture was infected with M. aeruginosa cells in the landscape water. After 24days, the removal ratios of nitrate and chlorophyll-a were high, 100% and 87.86%, respectively. The denitrification rate was approximately 0.118mgNO3(-)-N·L(-1)·h(-1). Moreover, the high-throughput sequencing result showed that Acinetobacter sp. J25 was obviously beneficial for chlorophyll-a and nitrate removal performance in the eutrophic landscape water treatment. Therefore, strain J25 is promising for the simultaneous removal of chlorophyll-a and nitrate in the eutrophic landscape water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.
-
Lai, Juo-Hsin; Yang, Jhih-Tian; Chern, Jeffy; Chen, Te-Li; Wu, Wan-Ling; Liao, Jiahn-Haur; Tsai, Shih-Feng; Liang, Suh-Yuen; Chou, Chi-Chi; Wu, Shih-Hsiung
2016-01-01
Nosocomial infectious outbreaks caused by multidrug-resistant Acinetobacter baumannii have emerged as a serious threat to human health. Phosphoproteomics of pathogenic bacteria has been used to identify the mechanisms of bacterial virulence and antimicrobial resistance. In this study, we used a shotgun strategy combined with high-accuracy mass spectrometry to analyze the phosphoproteomics of the imipenem-susceptible strain SK17-S and -resistant strain SK17-R. We identified 410 phosphosites on 248 unique phosphoproteins in SK17-S and 285 phosphosites on 211 unique phosphoproteins in SK17-R. The distributions of the Ser/Thr/Tyr/Asp/His phosphosites in SK17-S and SK17-R were 47.0%/27.6%/12.4%/8.0%/4.9% versus 41.4%/29.5%/17.5%/6.7%/4.9%, respectively. The Ser-90 phosphosite, located on the catalytic motif S(88)VS(90)K of the AmpC β-lactamase, was first identified in SK17-S. Based on site-directed mutagenesis, the nonphosphorylatable mutant S90A was found to be more resistant to imipenem, whereas the phosphorylation-simulated mutant S90D was sensitive to imipenem. Additionally, the S90A mutant protein exhibited higher β-lactamase activity and conferred greater bacterial protection against imipenem in SK17-S compared with the wild-type. In sum, our results revealed that in A. baumannii, Ser-90 phosphorylation of AmpC negatively regulates both β-lactamase activity and the ability to counteract the antibiotic effects of imipenem. These findings highlight the impact of phosphorylation-mediated regulation in antibiotic-resistant bacteria on future drug design and new therapies. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.
-
Cooper, Travis W; Pass, Steven E; Brouse, Sara D; Hall, Ronald G
2011-02-01
To discuss treatment options that can be used for treatment of Acinetobac/erinfections. A MEDLINE search (1966-November 2010) was conducted to identify English-language literature on pharmacotherapy of Acinetobacter and the bibliographies of pertinent articles. Programs and abstracts from infectious diseases meetings were also searched. Search terms included Acinetobacter, multidrug resistance, pharmacokinetics, pharmacodynamics, Monte Carlo simulation, nosocomial pneumonia, carbapenems, polymyxins, sulbactam, aminoglycosides, tetracyclines, tigecycline, rifampin, and fluoroquinolones. All articles were critically evaluated and all pertinent information was included in this review. Multidrug resistant (MDR) Acinetobacter, defined as resistance to 3 or more antimicrobial classes, has increased over the past decade. The incidence of carbapenem-resistant Acinetobacter is also increasing, leading to an increased use of dose optimization techniques and/or alternative antimicrobials, which is driven by local susceptibility patterns. However, Acinetobacter infections that are resistant to all commercially available antibiotics have been reported. General principles are available to guide dose optimization of aminoglycosides, β-lactams, fluoroquinolones, and tigecycline for infections due to gram-negative pathogens. Unfortunately, data specific to patients with Acinetobacter infections are limited. Recent pharmacokinetic-pharmacodynamic information has shed light on colistin dosing. The dilemma with colistin is its concentration-dependent killing, which makes once-daily dosing seem like an attractive option, but its short postantibiotic effect limits a clinician's ability to extend the dosing interval. Localized delivery of antimicrobials is also an attractive option due to the ability to increase drug concentration at the infection site while minimizing systemic adverse events, but more data are needed regarding this approach. Increased reliance on dosage optimization
-
Insertion sequence transposition determines imipenem resistance in Acinetobacter baumannii.
Kuo, Han-Yueh; Chang, Kai-Chih; Liu, Chih-Chin; Tang, Chuan Yi; Peng, Jhih-Hua; Lu, Chia-Wei; Tu, Chi-Chao; Liou, Ming-Li
2014-10-01
This study employed genomewide analysis to investigate potential resistance mechanisms in Acinetobacter baumannii following imipenem exposure. Imipenem-selected mutants were generated from the imipenem-susceptible strain ATCC 17978 by multistep selection resistance. Antibiotic susceptibilities were examined, and the selected mutants originated from the ATCC 17978 strain were confirmed by pulsed-field gel electrophoresis. The genomic sequence of a resistant mutant was analyzed using a next-generation sequencing platform, and genetic recombination was further confirmed by PCR. The result showed that phenotypic resistance was observed with carbapenem upon exposure to various concentrations of imipenem. Genomewide analysis showed that ISAba1 transposition was initiated by imipenem exposure at concentrations up to 0.5 mg/L. Transposition of ISAba1 upstream of blaOXA-95 was detected in all the selected mutants. The expression of blaOXA-95 was further analyzed by quantitative PCR, and the results demonstrated that a 200-fold increase in gene expression was required for resistance to imipenem. This study concluded that imipenem exposure at a concentration of 0.5 mg/L mediated the transposition of ISAba1 upstream of the blaOXA-95 gene and resulted in the overexpression of blaOXA-95 gene, which may play a major role in the resistance to imipenem in A. baumannii.
-
Acinetobacter community-acquired pneumonia in a healthy child.
Moreira Silva, G; Morais, L; Marques, L; Senra, V
2012-01-01
Acinetobacter is involved in a variety of infectious diseases primarily associated with healthcare. Recently there has been increasing evidence of the important role these pathogens play in community acquired infections. We report on the case of a previously healthy child, aged 28 months, admitted for fever, cough and pain on the left side of the chest, which on radiographic examination corresponded to a lower lobe necrotizing pneumonia. After detailed diagnostic work-up, community acquired Acinetobacter lwoffii pneumonia was diagnosed. The child had frequently shared respiratory equipment with elderly relatives with chronic obstructive pulmonary disease. As there were no other apparent risk factors, it could be assumed that the sharing of the equipment was the source of infection. The authors wish to draw attention to this possibility, that a necrotising community-acquired pneumonia due to Acinetobacter lwoffii can occur in a previously healthy child and to the dangers of inappropriate use and poor sterilisation of nebulisers. This case is a warning of the dangers that these bacteria may pose in the future in a community setting. Copyright © 2011 Sociedade Portuguesa de Pneumologia. Published by Elsevier España. All rights reserved.
-
Laboratory Maintenance of Acinetobacter baumannii.
Jacobs, Anna C; Zurawski, Daniel V
2014-11-03
Acinetobacter baumannii has recently drawn great interest in the microbiology research community due to the increase in clinical antibiotic resistance of this organism, and persistence of this bacterial species in the hospital environment. This unit outlines protocols for the growth and maintenance of A. baumannii in the laboratory. Copyright © 2014 John Wiley & Sons, Inc.
-
Park, Young Kyoung; Lee, Gyu Hong; Baek, Jin Yang; Chung, Doo Ryeon; Peck, Kyong Ran; Song, Jae-Hoon; Ko, Kwan Soo
2010-06-01
We investigated the characteristics of a total of 96 Acinetobacter spp. isolates that were shown to cause bacteremia and urinary tract infections (UTIs) from 10 university hospitals located in various regions of Korea from November 2006 to August 2007. The antimicrobial susceptibilities of these isolates were determined using a broth microdilution method, and the species were identified using molecular identification. In addition, we performed multilocus sequence typing for Acinetobacter baumannii subgroup A isolates. A. baumannii subgroup A was the most prevalent in patients with both bacteremia (32 isolates, 53.3%) and UTIs (20 isolates, 55.6%), followed by Acinetobacter genomic species 13TU (15.0% and 27.8% in bacteremia and UTIs, respectively). A. baumannii subgroup B and Acinetobacter junii were found exclusively in isolates causing bacteremia (seven and five isolates, respectively). Among 96 Acinetobacter spp. isolates, 19.8% were resistant to imipenem and 25.0% were resistant to meropenem. Most carbapenem-resistant A. baumannii isolates contained PER or oxacillinase-23-like enzymes (65.2% and 78.3%, respectively). In addition, 13.5% were resistant to polymyxin B and 17.7% were resistant to colistin. A. baumannii subgroup A isolates (52 isolates, 54.2%) showed higher resistance rates to most antimicrobial agents than other species, but not to colistin. Among A. baumannii subgroup A isolates, ST22 was the most prevalent genotype (33 isolates, 63.5%) and showed higher resistance rates to all antimicrobial agents than the other genotypes. In addition, four out of five polymyxin-resistant A. baumannii group A isolates belonged to ST22. Thus, dissemination of the main clone of A. baumannii, ST22, may contribute to the high resistance rates of Acinetobacter isolates to antimicrobials, including carbapenems, in Korea.
-
Rusansky, S; Avigad, R; Michaeli, S; Gutnick, D L
1987-01-01
A crude-oil-degrading Acinetobacter species, Acinetobacter calcoaceticus RA57, was isolated by standard enrichment culture techniques on the basis of its ability to utilize the oily sludge found in the vicinity of a local gas station. Strain RA57 was found to contain four plasmids: pSR1 (5.1 kilobases [kb]), pSR2 (5.4 kb), pSR3 (10.5 kb), and pSR4 (20 kb). Both supercoiled and open circular forms of the first three plasmids were identified by two-dimensional gel electrophoresis. Restriction endonuclease analysis of pSR4 demonstrated that the plasmid contained a circular map. Colonies were isolated at random after growth in the presence of acridine orange and found to fall into two categories: (i) those which had lost the ability to grow on and disperse crude oil in liquid culture and concurrently were cured of pSR4 and (ii) those which retained the ability to both grow on and disperse crude oil and which contained pSR4. Strains from the first class continued to grow on hydrocarbon vapors, indicating that the defect associated with the curing of pSR4 was related to the physical interaction of the cells with the hydrocarbon substrate, rather than to its metabolism. No differences in either adherence to hydrocarbons or production of extracellular emulsifying activity were found between the two classes of mutants. In growth experiments on crude oil in mixed culture with strains which either contained or lacked pSR4, no sparing of the growth defect was observed. The results are consistent with the possibility that pSR4 encodes a factor(s) which is tightly associated with the cell surface. Images PMID:2821903
-
Kulkarni, Sughosh S; Madalgi, Radhika; Ajantha, Ganavalli S; Kulkarni, Raghavendra D
2017-01-01
Acinetobacter is grouped under nonfermenting Gram-negative bacilli. It is increasingly isolated from pathological samples. The ability of this genus to acquire drug resistance and spread in the hospital settings is posing a grave problem in healthcare. Specific treatment protocols are advocated for Acinetobacter infections. Hence, rapid identification and drug susceptibility profiling are critical in the management of these infections. To standardize an in-house polymerase chain reaction (PCR) for identification of genus Acinetobacter and to compare PCR with two protocols for its phenotypic identification. A total of 96 clinical isolates of Acinetobacter were included in the study. An in-house PCR for genus level identification of Acinetobacter was standardized. All the isolates were phenotypically identified by two protocols. The results of PCR and phenotypic identification protocols were compared. The in-house PCR standardized was highly sensitive and specific for the genus Acinetobacter . There was 100% agreement between the phenotypic and molecular identification of the genus. The preliminary identification tests routinely used in clinical laboratories were also in complete agreement with phenotypic and molecular identification. The in-house PCR for genus level identification is specific and sensitive. However, it may not be essential for routine identification as the preliminary phenotypic identification tests used in the clinical laboratory reliably identify the genus Acinetobacter .
-
Osmotic Compounds Enhance Antibiotic Efficacy against Acinetobacter baumannii Biofilm Communities
Falghoush, Azeza; Beyenal, Haluk; Besser, Thomas E.; Omsland, Anders
2017-01-01
ABSTRACT Biofilm-associated infections are a clinical challenge, in part because a hydrated matrix protects the bacterial community from antibiotics. Herein, we evaluated how different osmotic compounds (maltodextrin, sucrose, and polyethylene glycol [PEG]) enhance antibiotic efficacy against Acinetobacter baumannii biofilm communities. Established (24-h) test tube biofilms (strain ATCC 17978) were treated with osmotic compounds in the presence or absence of 10× the MIC of different antibiotics (50 μg/ml tobramycin, 20 μg/ml ciprofloxacin, 300 μg/ml chloramphenicol, 30 μg/ml nalidixic acid, or 100 μg/ml erythromycin). Combining antibiotics with hypertonic concentrations of the osmotic compounds for 24 h reduced the number of biofilm bacteria by 5 to 7 log (P < 0.05). Increasing concentrations of osmotic compounds improved the effect, but there was a trade-off with increasing solution viscosity, whereby low-molecular-mass compounds (sucrose, 400-Da PEG) worked better than higher-mass compounds (maltodextrin, 3,350-Da PEG). Ten other A. baumannii strains were similarly treated with 400-Da PEG and tobramycin, resulting in a mean 2.7-log reduction in recoverable bacteria compared with tobramycin treatment alone. Multivariate regression models with data from different osmotic compounds and nine antibiotics demonstrated that the benefit from combining hypertonic treatments with antibiotics is a function of antibiotic mass and lipophilicity (r2 > 0.82; P < 0.002), and the relationship was generalizable for biofilms formed by A. baumannii and Escherichia coli K-12. Augmenting topical antibiotic therapies with a low-mass hypertonic treatment may enhance the efficacy of antibiotics against wound biofilms, particularly when using low-mass hydrophilic antibiotics. IMPORTANCE Biofilms form a barrier that protects bacteria from environmental insults, including exposure to antibiotics. We demonstrated that multiple osmotic compounds can enhance antibiotic efficacy against
-
21 CFR 866.3010 - Acinetobacter calcoaceticus serological reagents.
Code of Federal Regulations, 2011 CFR
2011-04-01
... this bacterium from cultured isolates derived from clinical specimens. The identification aids in the diagnosis of disease caused by the bacterium Acinetobacter calcoaceticus and provides epidemiological...
-
21 CFR 866.3010 - Acinetobacter calcoaceticus serological reagents.
Code of Federal Regulations, 2010 CFR
2010-04-01
... this bacterium from cultured isolates derived from clinical specimens. The identification aids in the diagnosis of disease caused by the bacterium Acinetobacter calcoaceticus and provides epidemiological...
-
Wang, Tieshan; Su, Jianrong
2016-12-28
Exploring novel antibiotics is necessary for multidrug-resistant pathogenic bacteria. Because the probiotics in soybean food have antimicrobial activities, we investigated their effects on multidrug-resistant Acinetobacter baumannii . Nineteen multidrug-resistant A. baumannii strains were clinifcally isolated as an experimental group and 11 multidrug-sensitive strains as controls. The growth rates of all bacteria were determined by using the analysis for xCELLigence Real-Time Cell. The combination of antibiotics showed synergistic effects on the strains in the control group but no effect on the strains in the experimental group. Efflux pump gene adeS was absent in all the strains from the control group, whereas it exists in all the strains from the experimental group. Furthermore, all the strains lost multidrug resistance when an adeS inhibitor was used. One strain of probiotics isolated from soybean food showed high antimicrobial activity for multidrug-resistant A. baumannii . The isolated strain belongs to Bacillus subtilis according to 16S RNA analysis. Furthermore, E. coli showed multidrug resistance when it was transformed with the adeS gene from A. baumannii whereas the resistant bacteria could be inhibited completely by isolated Bacillus subtilis . Thus, probiotics from soybean food provide potential antibiotics against multidrug-resistant pathogenic bacteria.
-
Dong, Hao; Xia, Wenjie; Dong, Honghong; She, Yuehui; Zhu, Panfeng; Liang, Kang; Zhang, Zhongzhi; Liang, Chuanfu; Song, Zhaozheng; Sun, Shanshan; Zhang, Guangqing
2016-01-01
Biosurfactant producers are crucial for incremental oil production in microbial enhanced oil recovery (MEOR) processes. The isolation of biosurfactant-producing bacteria from oil reservoirs is important because they are considered suitable for the extreme conditions of the reservoir. In this work, a novel biosurfactant-producing strain Acinetobacter junii BD was isolated from a reservoir to reduce surface tension and emulsify crude oil. The biosurfactants produced by the strain were purified and then identified via electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR-MS). The biosurfactants generated by the strain were concluded to be rhamnolipids, the dominant rhamnolipids were C26H48O9, C28H52O9, and C32H58O13. The optimal carbon source and nitrogen source for biomass and biosurfactant production were NaNO3 and soybean oil. The results showed that the content of acid components increased with the progress of crude oil biodegradation. A glass micromodel test demonstrated that the strain significantly increased oil recovery through interfacial tension reduction, wettability alteration and the mobility of microorganisms. In summary, the findings of this study indicate that the newly developed BD strain and its metabolites have great potential in MEOR. PMID:27872613
-
Dong, Hao; Xia, Wenjie; Dong, Honghong; She, Yuehui; Zhu, Panfeng; Liang, Kang; Zhang, Zhongzhi; Liang, Chuanfu; Song, Zhaozheng; Sun, Shanshan; Zhang, Guangqing
2016-01-01
Biosurfactant producers are crucial for incremental oil production in microbial enhanced oil recovery (MEOR) processes. The isolation of biosurfactant-producing bacteria from oil reservoirs is important because they are considered suitable for the extreme conditions of the reservoir. In this work, a novel biosurfactant-producing strain Acinetobacter junii BD was isolated from a reservoir to reduce surface tension and emulsify crude oil. The biosurfactants produced by the strain were purified and then identified via electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR-MS). The biosurfactants generated by the strain were concluded to be rhamnolipids, the dominant rhamnolipids were C 26 H 48 O 9 , C 28 H 52 O 9 , and C 32 H 58 O 13 . The optimal carbon source and nitrogen source for biomass and biosurfactant production were NaNO 3 and soybean oil. The results showed that the content of acid components increased with the progress of crude oil biodegradation. A glass micromodel test demonstrated that the strain significantly increased oil recovery through interfacial tension reduction, wettability alteration and the mobility of microorganisms. In summary, the findings of this study indicate that the newly developed BD strain and its metabolites have great potential in MEOR.
-
Norsigian, Charles J; Kavvas, Erol; Seif, Yara; Palsson, Bernhard O; Monk, Jonathan M
2018-01-01
Acinetobacter baumannii has become an urgent clinical threat due to the recent emergence of multi-drug resistant strains. There is thus a significant need to discover new therapeutic targets in this organism. One means for doing so is through the use of high-quality genome-scale reconstructions. Well-curated and accurate genome-scale models (GEMs) of A. baumannii would be useful for improving treatment options. We present an updated and improved genome-scale reconstruction of A. baumannii AYE, named iCN718, that improves and standardizes previous A. baumannii AYE reconstructions. iCN718 has 80% accuracy for predicting gene essentiality data and additionally can predict large-scale phenotypic data with as much as 89% accuracy, a new capability for an A. baumannii reconstruction. We further demonstrate that iCN718 can be used to analyze conserved metabolic functions in the A. baumannii core genome and to build strain-specific GEMs of 74 other A. baumannii strains from genome sequence alone. iCN718 will serve as a resource to integrate and synthesize new experimental data being generated for this urgent threat pathogen.
-
Lee, Kyungwon; Lim, Chang Hyun; Cho, Ji Hyun; Lee, Wee Gyo; Uh, Young; Kim, Hwi Jun; Yong, Dongeun
2006-01-01
A nationwide antimicrobial resistance surveillance has been conducted since 1997 in Korea. In this study, susceptibility test data generated in 2004 by KONSAR group hospitals were analyzed and compared to those at a commercial laboratory. In hospitals, the rank orders of organisms in 2004 were identical to those in 2003. The most prevalent species was Staphylococcus aureus (20.2%) in hospitals, but Escherichia coli (29.7%) in the commercial laboratory. The proportions of Enterococcus faecium to all isolates of Enterococcus faecalis plus E. faecium were 47.2% in hospitals and 24.9% in the commercial laboratory. The mean resistance rates of significant antimicrobial-organism combinations in hospitals were: oxacillin-resistant S. aureus (68%), oxacillin-resistant (penicillin-nonsusceptible) Streptococcus pneumoniae (68%), vancomycin-resistant E. faecium (25%), cefotaxime-resistant E. coli (14%), ceftazidime- and cefoxitin-resistant Klebsiella pneumoniae (34% and 32%, respectively), and imipenem-resistant Acinetobacter spp. and Pseudomonas aeruginosa (17% and 24%, respectively). In conclusion, oxacillin-resistant staphylococci, expanded-spectrum cephalosporin-resistant K. pneumoniae, and imipenem-resistant Acinetobacter spp. and P. aeruginosa were prevalent in 2004. Increasing trends were observed for vancomycin-resistant E. faecium, cefoxitin-resistant E. coli and K. pneumoniae, and imipenem-resistant Acinetobacter spp. and P. aeruginosa. Certain antimicrobial-organism combinations were also prevalent among the commercial laboratory-tested strains. PMID:17066507
-
Chen, Yu; Li, Chen; Zhou, Zhengxi; Wen, Jianping; You, Xueyi; Mao, Youzhi; Lu, Chunzhe; Huo, Guangxin; Jia, Xiaoqiang
2014-04-01
In this study, two strains, Acinetobacter sp. XM-02 and Pseudomonas sp. XM-01, were isolated from soil samples polluted by crude oil at Bohai offshore. The former one could degrade alkane hydrocarbons (crude oil and diesel, 1:4 (v/v)) and crude oil efficiently; the latter one failed to grow on alkane hydrocarbons but could produce rhamnolipid (a biosurfactant) with glycerol as sole carbon source. Compared with pure culture, mixed culture of the two strains showed higher capability in degrading alkane hydrocarbons and crude oil of which degradation rate were increased from 89.35 and 74.32 ± 4.09 to 97.41 and 87.29 ± 2.41 %, respectively. In the mixed culture, Acinetobacter sp. XM-02 grew fast with sufficient carbon source and produced intermediates which were subsequently utilized for the growth of Pseudomonas sp. XM-01 and then, rhamnolipid was produced by Pseudomonas sp. XM-01. Till the end of the process, Acinetobacter sp. XM-02 was inhibited by the rapid growth of Pseudomonas sp. XM-01. In addition, alkane hydrocarbon degradation rate of the mixed culture increased by 8.06 to 97.41 % compared with 87.29 % of the pure culture. The surface tension of medium dropping from 73.2 × 10(-3) to 28.6 × 10(-3) N/m. Based on newly found cooperation between the degrader and the coworking strain, rational investigations and optimal strategies to alkane hydrocarbons biodegradation were utilized for enhancing crude oil biodegradation.
-
Prakash, Dhan; Kumar, Ravi; Jain, R. K.; Tiwary, B. N.
2011-01-01
The organism Acinetobacter sp. RKJ12 is capable of utilizing 2-chloro-4-nitrobenzoic acid (2C4NBA) as a sole source of carbon, nitrogen, and energy. In the degradation of 2C4NBA by strain RKJ12, various metabolites were isolated and identified by a combination of chromatographic, spectroscopic, and enzymatic activities, revealing a novel assimilation pathway involving both oxidative and reductive catabolic mechanisms. The metabolism of 2C4NBA was initiated by oxidative ortho dehalogenation, leading to the formation of 2-hydroxy-4-nitrobenzoic acid (2H4NBA), which subsequently was metabolized into 2,4-dihydroxybenzoic acid (2,4-DHBA) by a mono-oxygenase with the concomitant release of chloride and nitrite ions. Stoichiometric analysis indicated the consumption of 1 mol O2 per conversion of 2C4NBA to 2,4-DHBA, ruling out the possibility of two oxidative reactions. Experiments with labeled H218O and 18O2 indicated the involvement of mono-oxygenase-catalyzed initial hydrolytic dechlorination and oxidative denitration mechanisms. The further degradation of 2,4-DHBA then proceeds via reductive dehydroxylation involving the formation of salicylic acid. In the lower pathway, the organism transformed salicylic acid into catechol, which was mineralized by the ortho ring cleavage catechol-1,2-dioxygenase to cis, cis-muconic acid, ultimately forming tricarboxylic acid cycle intermediates. Furthermore, the studies carried out on a 2C4NBA− derivative and a 2C4NBA+ transconjugant demonstrated that the catabolic genes for the 2C4NBA degradation pathway possibly reside on the ∼55-kb transmissible plasmid present in RKJ12. PMID:21803909
-
Mohd. Rani, Farahiyah; A. Rahman, Nor Iza; Ismail, Salwani; Alattraqchi, Ahmed Ghazi; Cleary, David W.; Clarke, Stuart C.; Yeo, Chew Chieng
2017-01-01
Acinetobacter spp. are important nosocomial pathogens, in particular the Acinetobacter baumannii-calcoaceticus complex, which have become a global public health threat due to increasing resistance to carbapenems and almost all other antimicrobial compounds. High rates of resistance have been reported among countries in Southeast Asia, including Malaysia. In this review, we examine the antimicrobial resistance profiles of Acinetobacter spp. hospital isolates from Malaysia over a period of nearly three decades (1987–2016) with data obtained from various peer-reviewed publications as well as the Malaysian National Surveillance on Antibiotic Resistance (NSAR). NSAR data indicated that for most antimicrobial compounds, including carbapenems, the peak resistance rates were reached around 2008–2009 and thereafter, rates have remained fairly constant (e.g., 50–60% for carbapenems). Individual reports from various hospitals in Peninsular Malaysia do not always reflect the nationwide resistance rates and often showed higher rates of resistance. We also reviewed the epidemiology and mechanisms of resistance that have been investigated in Malaysian Acinetobacter spp. isolates, particularly carbapenem resistance and found that blaOXA-23 is the most prevalent acquired carbapenemase-encoding gene. From the very few published reports and whole genome sequences that are available, most of the Acinetobacter spp. isolates from Malaysia belonged to the Global Clone 2 (GC2) CC92 group with ST195 being the predominant sequence type. The quality of data and analysis in the national surveillance reports could be improved and more molecular epidemiology and genomics studies need to be carried out for further in-depth understanding of Malaysian Acinetobacter spp. isolates. PMID:29312188
-
Mohd Rani, Farahiyah; A Rahman, Nor Iza; Ismail, Salwani; Alattraqchi, Ahmed Ghazi; Cleary, David W; Clarke, Stuart C; Yeo, Chew Chieng
2017-01-01
Acinetobacter spp. are important nosocomial pathogens, in particular the Acinetobacter baumannii - calcoaceticus complex, which have become a global public health threat due to increasing resistance to carbapenems and almost all other antimicrobial compounds. High rates of resistance have been reported among countries in Southeast Asia, including Malaysia. In this review, we examine the antimicrobial resistance profiles of Acinetobacter spp. hospital isolates from Malaysia over a period of nearly three decades (1987-2016) with data obtained from various peer-reviewed publications as well as the Malaysian National Surveillance on Antibiotic Resistance (NSAR). NSAR data indicated that for most antimicrobial compounds, including carbapenems, the peak resistance rates were reached around 2008-2009 and thereafter, rates have remained fairly constant (e.g., 50-60% for carbapenems). Individual reports from various hospitals in Peninsular Malaysia do not always reflect the nationwide resistance rates and often showed higher rates of resistance. We also reviewed the epidemiology and mechanisms of resistance that have been investigated in Malaysian Acinetobacter spp. isolates, particularly carbapenem resistance and found that bla OXA-23 is the most prevalent acquired carbapenemase-encoding gene. From the very few published reports and whole genome sequences that are available, most of the Acinetobacter spp. isolates from Malaysia belonged to the Global Clone 2 (GC2) CC92 group with ST195 being the predominant sequence type. The quality of data and analysis in the national surveillance reports could be improved and more molecular epidemiology and genomics studies need to be carried out for further in-depth understanding of Malaysian Acinetobacter spp. isolates.
-
Contamination of Ambient Air with Acinetobacter baumannii on Consecutive Inpatient Days.
Shimose, Luis A; Doi, Yohei; Bonomo, Robert A; De Pascale, Dennise; Viau, Roberto A; Cleary, Timothy; Namias, Nicholas; Kett, Daniel H; Munoz-Price, L Silvia
2015-07-01
Acinetobacter-positive patients had their ambient air tested for up to 10 consecutive days. The air was Acinetobacter positive for an average of 21% of the days; the rate of contamination was higher among patients colonized in the rectum than in the airways (relative risk [RR], 2.35; P = 0.006). Of the 6 air/clinical isolate pairs available, 4 pairs were closely related according to rep-PCR results. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
-
Gildas Comlan Zohoun, Alban; Moket, Danièle; El Hamzaoui, Sakina
2013-01-01
We studied the production of metallo-β-lactamases (MBL) in Acinetobacter baumannii and Pseudomonas aeruginosa strains resistant to imipenem at the Rabat Mohammed V military teaching hospital, according to Yong et al.'s method, using a sterilized solution of EDTA 0.5 M pH 8. One hundred and five bacterial strains (48 A. baumannii and 57 P. aeruginosa) were identified. 45 (42.9%) with 34 A. baumannii and 11 P. aeruginosa were resistant to imipenem. The prevalence of MBL producing strains was 22.2% (10/45). The existence of this isolates resistant to imipenem by producing metallo-β-lactamases is an emerging public health problem. It is necessary to implemente infection control programs to avoid spreading of multidrug resistant bacteria.
-
Stojowska, Karolina; Krawczyk, Beata
2014-01-01
We have designed a new ddLMS PCR (double digestion Ligation Mediated Suppression PCR) method based on restriction site polymorphism upstream from the specific target sequence for the simultaneous identification and differentiation of bacterial strains. The ddLMS PCR combines a simple PCR used for species or genus identification and the LM PCR strategy for strain differentiation. The bacterial identification is confirmed in the form of the PCR product(s), while the length of the PCR product makes it possible to differentiate between bacterial strains. If there is a single copy of the target sequence within genomic DNA, one specific PCR product is created (simplex ddLMS PCR), whereas for multiple copies of the gene the fingerprinting patterns can be obtained (multiplex ddLMS PCR). The described ddLMS PCR method is designed for rapid and specific strain differentiation in medical and microbiological studies. In comparison to other LM PCR it has substantial advantages: enables specific species' DNA-typing without the need for pure bacterial culture selection, is not sensitive to contamination with other cells or genomic DNA, and gives univocal "band-based" results, which are easy to interpret. The utility of ddLMS PCR was shown for Acinetobacter calcoaceticus-baumannii (Acb) complex, the genetically closely related and phenotypically similar species and also important nosocomial pathogens, for which currently, there are no recommended methods for screening, typing and identification. In this article two models are proposed: 3' recA-ddLMS PCR-MaeII/RsaI for Acb complex interspecific typing and 5' rrn-ddLMS PCR-HindIII/ApaI for Acinetobacter baumannii intraspecific typing. ddLMS PCR allows not only for DNA-typing but also for confirmation of species in one reaction. Also, practical guidelines for designing a diagnostic test based on ddLMS PCR for genotyping different species of bacteria are provided.
-
Stojowska, Karolina; Krawczyk, Beata
2014-01-01
We have designed a new ddLMS PCR (double digestion Ligation Mediated Suppression PCR) method based on restriction site polymorphism upstream from the specific target sequence for the simultaneous identification and differentiation of bacterial strains. The ddLMS PCR combines a simple PCR used for species or genus identification and the LM PCR strategy for strain differentiation. The bacterial identification is confirmed in the form of the PCR product(s), while the length of the PCR product makes it possible to differentiate between bacterial strains. If there is a single copy of the target sequence within genomic DNA, one specific PCR product is created (simplex ddLMS PCR), whereas for multiple copies of the gene the fingerprinting patterns can be obtained (multiplex ddLMS PCR). The described ddLMS PCR method is designed for rapid and specific strain differentiation in medical and microbiological studies. In comparison to other LM PCR it has substantial advantages: enables specific species' DNA-typing without the need for pure bacterial culture selection, is not sensitive to contamination with other cells or genomic DNA, and gives univocal “band-based” results, which are easy to interpret. The utility of ddLMS PCR was shown for Acinetobacter calcoaceticus-baumannii (Acb) complex, the genetically closely related and phenotypically similar species and also important nosocomial pathogens, for which currently, there are no recommended methods for screening, typing and identification. In this article two models are proposed: 3′ recA-ddLMS PCR-MaeII/RsaI for Acb complex interspecific typing and 5′ rrn-ddLMS PCR-HindIII/ApaI for Acinetobacter baumannii intraspecific typing. ddLMS PCR allows not only for DNA-typing but also for confirmation of species in one reaction. Also, practical guidelines for designing a diagnostic test based on ddLMS PCR for genotyping different species of bacteria are provided. PMID:25522278
-
Zhou, Weilong; Feng, Yu; Zong, Zhiyong
2018-01-01
Two lytic bacteriophages, WCHABP1 and WCHABP12, were recovered from hospital sewage and were able to infect 9 and 12 out of 18 carbapenem-resistant Acinetobacter baumannii clinical strains, which belonged to different clones. Electron microscopy scan showed that both bacteriophages had the similar morphology as those of the Myoviridae family. Whole genomic sequencing revealed 45.4- or 45.8-kb genome with a 37.6% GC content for WCHABP1 and WCHABP12, both of which showed significant DNA sequence similarity with bacteriophages of the Ap22virus genus within the Myoviridae family. Taxonomic analysis was therefore performed following the proposal approved by the International Committee on Taxonomy of Viruses, which confirmed that WCHABP1 and WCHABP12 represented two new species of the Ap22virus genus. No tRNAs but 88 and 89 open reading frames (ORFs) were predicted for the two bacteriophages, among which 22 and 21 had known function and encoded proteins for morphogenesis, packaging, lysis, and nucleiotide metabolism. The C-terminal amino acids of the large unit of fiber tail proteins varied between the bacteriophages, which may explain their different host ranges. For most lytic bacteriophages, a set of holin and endolysin are required for lysis. However, no known holin-encoding genes were identified in WCHABP1 and WCHABP12, suggesting that they may use alternative, yet-to-be-identified, novel holins for host cell membrane lysis. To test the efficacy of the bacteriophages in protecting against A. baumannii infection, a Galleria mellonella larva model was used. Only <20% G. mellonella larvae survived at 96 h after being infected by carbapenem-resistant A. baumannii strains, from which the two bacteriophages were recovered. With the administration of WCHABP1 and WCHABP12, the survival of larvae increased to 75%, while the treatment of polymyxin B only slightly increased the survival rate to 25%. The isolation of two new lytic bacteriophages in this study could expand our
-
Transcriptome profiling in imipenem-selected Acinetobacter baumannii.
Chang, Kai-Chih; Kuo, Han-Yueh; Tang, Chuan Yi; Chang, Cheng-Wei; Lu, Chia-Wei; Liu, Chih-Chin; Lin, Huei-Ru; Chen, Kuan-Hsueh; Liou, Ming-Li
2014-09-26
Carbapenem-resistance in Acinetobacter baumannii has gradually become a global challenge. To identify the genes involved in carbapenem resistance in A. baumannii, the transcriptomic responses of the completely sequenced strain ATCC 17978 selected with 0.5 mg/L (IPM-2 m) and 2 mg/L (IPM-8 m) imipenem were investigated using RNA-sequencing to identify differences in the gene expression patterns. A total of 88 and 68 genes were differentially expressed in response to IPM-2 m and IPM-8 m selection, respectively. Among the expressed genes, 50 genes were highly expressed in IPM-2 m, 30 genes were highly expressed in IPM-8 m, and 38 genes were expressed common in both strains. Six groups of genes were simultaneously expressed in IPM-2 m and IPM-8 m mutants. The three gene groups involved in DNA recombination were up-regulated, including recombinase, transposase and DNA repair, and beta-lactamase OXA-95 and homologous recombination. The remaining gene groups involved in biofilm formation were down-regulated, including quorum sensing, secretion systems, and the csu operon. The antibiotic resistance determinants, including RND efflux transporters and multidrug resistance pumps, were over-expressed in response to IPM-2 m selection, followed by a decrease in response to IPM-8 m selection. Among the genes over-expressed in both strains, blaOXA-95, previously clustered with the blaOXA-51-like family, showed 14-fold (IPM-2 m) to 330-fold (IPM-8 m) over-expression. The expression of blaOXA-95 in IPM-2 m and IPM-8 m cells was positively correlated with the rate of imipenem hydrolysis, as demonstrated through Liquid Chromatography-Mass Spectrometry/Mass Spectrometry, suggesting that blaOXA-95 plays a critical role in conferring carbapenem resistance. In addition, A. baumannii shows an inverse relationship between carbapenem resistance and biofilm production. Gene recombination and blaOXA-95 play critical roles in carbapenem resistance in A. baumannii. Taken together, the results of
-
Unno, Yuka; Ubagai, Tsuneyuki; Ono, Yasuo
2018-01-01
We investigated the numbers of planktonic and biofilm cells and the expression levels of genes encoding efflux pumps and biofilm-related proteins in 10 clinical isolates of multi-drug resistant Acinetobacter baumannii (MDRA) as well as in its standard strain ATCC 19606 in the presence of colistin (CST), polymyxin B (PMB), minomycin (MIN), and tigecycline (TGC) at their respective sub-MICs. The number of planktonic and biofilm cells of ATCC 19606 decreased in the presence of all aforementioned antibiotics in a dose-dependent manner. Cell number also decreased in two representative MDRA strains, R2 and R3, in the presence of MIN and TGC in a dose-dependent manner. In contrast, the number of biofilm cells in these two strains increased in the presence of CST, while they increased significantly in the presence of PMB in R2 only. Pearson correlation analysis revealed that the number of biofilm cells was positively and significantly correlated with the mRNA levels of genes encoding efflux pumps (adeB and adeG) and autoinducer synthase (abaI) in strain R2 and adeB, adeG, adeJ, poly-acetyl-glucosamine-porin (pgaA), and abaI in strain R3 in the presence of CST. It was positively and significantly correlated with the mRNA levels of genes encoding adeB in strain R2 and an outer membrane protein A (ompA) and biofilm-associated protein (bap) in strain R3 in the presence of PMB. These results provide valuable insights into the biofilm formation potency of clinical isolates of MDRA that depends on efflux pumps and biofilm-related genes and its regulation by antibiotics. PMID:29554105
-
Heteroresistance to Cephalosporins and Penicillins in Acinetobacter baumannii
Hung, Kuei-Hsiang; Wang, Ming-Cheng; Huang, Ay-Huey; Yan, Jing-Jou
2012-01-01
Heteroresistance to antimicrobial agents may affect susceptibility test results and therapeutic success. In this study, we investigated heteroresistance to cephalosporins and penicillins in Acinetobacter baumannii, a major pathogen causing nosocomial infections. Two A. baumannii isolates exhibited heteroresistance to ampicillin-sulbactam, ticarcillin-clavulanic acid, cefepime, and cefpirome, showing a distinct colony morphology of circular rings within the inhibition halos. Pulsed-field gel electrophoresis (PFGE) and outer membrane protein (OMP) analysis demonstrated that subpopulations around the disks/Etest strips and the original strains all belonged to the same PFGE type and OMP profile. Population analysis profile (PAP) showed the presence of heteroresistant subpopulations with high cefepime resistance levels in two isolates (008 and 328). Interestingly, A. baumannii 008 contained two peaks: one was grown in the presence of up to 1 μg of cefepime/ml, the other apparently occurred when the concentration of cefepime was raised to 256 μg/ml. After serial passages without exposure to cefepime, the PAP curve maintained the same trend observed for the original strain of A. baumannii 008. However, the PAP curve showed a shift to relatively lower cefepime resistance (from 256 to 64 μg/ml) in A. baumannii 328 after 10 passages in antibiotic-free Mueller-Hinton agar plates. Convergence to a monotypic resistance phenotype did not occur. Growth rate analysis revealed that slower growth in resistant subpopulations may provide a strategy against antibiotic challenge. To our knowledge, this is the first report of heteroresistance to cephalosporins and penicillins in A. baumannii. PMID:22189112
-
Heteroresistance to cephalosporins and penicillins in Acinetobacter baumannii.
Hung, Kuei-Hsiang; Wang, Ming-Cheng; Huang, Ay-Huey; Yan, Jing-Jou; Wu, Jiunn-Jong
2012-03-01
Heteroresistance to antimicrobial agents may affect susceptibility test results and therapeutic success. In this study, we investigated heteroresistance to cephalosporins and penicillins in Acinetobacter baumannii, a major pathogen causing nosocomial infections. Two A. baumannii isolates exhibited heteroresistance to ampicillin-sulbactam, ticarcillin-clavulanic acid, cefepime, and cefpirome, showing a distinct colony morphology of circular rings within the inhibition halos. Pulsed-field gel electrophoresis (PFGE) and outer membrane protein (OMP) analysis demonstrated that subpopulations around the disks/Etest strips and the original strains all belonged to the same PFGE type and OMP profile. Population analysis profile (PAP) showed the presence of heteroresistant subpopulations with high cefepime resistance levels in two isolates (008 and 328). Interestingly, A. baumannii 008 contained two peaks: one was grown in the presence of up to 1 μg of cefepime/ml, the other apparently occurred when the concentration of cefepime was raised to 256 μg/ml. After serial passages without exposure to cefepime, the PAP curve maintained the same trend observed for the original strain of A. baumannii 008. However, the PAP curve showed a shift to relatively lower cefepime resistance (from 256 to 64 μg/ml) in A. baumannii 328 after 10 passages in antibiotic-free Mueller-Hinton agar plates. Convergence to a monotypic resistance phenotype did not occur. Growth rate analysis revealed that slower growth in resistant subpopulations may provide a strategy against antibiotic challenge. To our knowledge, this is the first report of heteroresistance to cephalosporins and penicillins in A. baumannii.
-
Li, Puyuan; Huang, Yong; Yu, Lan; Liu, Yannan; Niu, Wenkai; Zou, Dayang; Liu, Huiying; Zheng, Jing; Yin, Xiuyun; Yuan, Jing; Yuan, Xin; Bai, Changqing
2017-09-01
Heteroresistance is a phenomenon in which there are various responses to antibiotics from bacterial cells within the same population. Here, we isolated and characterised an imipenem heteroresistant Acinetobacter baumannii strain (HRAB-85). The genome of strain HRAB-85 was completely sequenced and analysed to understand its antibiotic resistance mechanisms. Population analysis and multilocus sequence typing were performed. Subpopulations grew in the presence of imipenem at concentrations of up to 64μg/mL, and the strain was found to belong to ST208. The total length of strain HRAB-85 was 4,098,585bp with a GC content of 39.98%. The genome harboured at least four insertion sequences: the common ISAba1, ISAba22, ISAba24, and newly reported ISAba26. Additionally, 19 antibiotic-resistance genes against eight classes of antimicrobial agents were found, and 11 genomic islands (GIs) were identified. Among them, GI3, GI10, and GI11 contained many ISs and antibiotic-resistance determinants. The existence of imipenem heteroresistant phenotypes in A. baumannii was substantiated in this hospital, and imipenem pressure, which could induce imipenem-heteroresistant subpopulations, may select for highly resistant strains. The complete genome sequencing and bioinformatics analysis of HRAB-85 could improve our understanding of the epidemiology and resistance mechanisms of carbapenem-heteroresistant A. baumannii. Copyright © 2017. Published by Elsevier Ltd.
-
Fang, Qing; Fan, Zhengqiu; Xie, Yujing; Wang, Xiangrong; Li, Kun; Liu, Yafeng
2016-01-01
The quest for new, promising and indigenous plant growth-promoting rhizobacteria and a deeper understanding of their relationship with plants are important considerations in the improvement of phytoremediation. This study focuses on the screening of plant beneficial Cu/Zn-resistant strains and assessment of their bioremediation potential (metal solubilization/tolerance/biosorption and effects on growth of Brassica napus seedlings) to identify suitable rhizobacteria and examine their roles in microbes-assisted phytoremediation. Sixty Cu/Zn-resistant rhizobacteria were initially isolated from Sonchus oleraceus grown at a multi-metal-polluted site in Shanghai, China. From these strains, 19 isolates that were all resistant to 300 mg⋅L -1 Cu as well as 300 mg⋅L -1 Zn, and could simultaneously grow on Dworkin-Foster salt minimal medium containing 1-aminocyclopropane-1-carboxylic acid were preliminarily selected. Of those 19 isolates, 10 isolates with superior plant growth-promoting properties (indole-3-acetic acid production, siderophore production, and insoluble phosphate solubilization) were secondly chosen and further evaluated to identify those with the highest bioremediation potential and capacity for bioaugmentation. Strain S44, identified as Acinetobacter sp. FQ-44 based on 16S rDNA sequencing, was specifically chosen as the most favorable strain owing to its strong capabilities to (1) promote the growth of rape seedlings (significantly increased root length, shoot length, and fresh weight by 92.60%, 31.00%, and 41.96%, respectively) under gnotobiotic conditions; (2) tolerate up to 1000 mg⋅L -1 Cu and 800 mg⋅L -1 Zn; (3) mobilize the highest concentrations of water-soluble Cu, Zn, Pb, and Fe (16.99, 0.98, 0.08, and 3.03 mg⋅L -1 , respectively); and (4) adsorb the greatest quantities of Cu and Zn (7.53 and 6.61 mg⋅g -1 dry cell, respectively). Our findings suggest that Acinetobacter sp. FQ-44 could be exploited for bacteria-assisted phytoextraction
-
Fang, Qing; Fan, Zhengqiu; Xie, Yujing; Wang, Xiangrong; Li, Kun; Liu, Yafeng
2016-01-01
The quest for new, promising and indigenous plant growth-promoting rhizobacteria and a deeper understanding of their relationship with plants are important considerations in the improvement of phytoremediation. This study focuses on the screening of plant beneficial Cu/Zn-resistant strains and assessment of their bioremediation potential (metal solubilization/tolerance/biosorption and effects on growth of Brassica napus seedlings) to identify suitable rhizobacteria and examine their roles in microbes-assisted phytoremediation. Sixty Cu/Zn-resistant rhizobacteria were initially isolated from Sonchus oleraceus grown at a multi-metal-polluted site in Shanghai, China. From these strains, 19 isolates that were all resistant to 300 mg⋅L-1 Cu as well as 300 mg⋅L-1 Zn, and could simultaneously grow on Dworkin–Foster salt minimal medium containing 1-aminocyclopropane-1-carboxylic acid were preliminarily selected. Of those 19 isolates, 10 isolates with superior plant growth-promoting properties (indole-3-acetic acid production, siderophore production, and insoluble phosphate solubilization) were secondly chosen and further evaluated to identify those with the highest bioremediation potential and capacity for bioaugmentation. Strain S44, identified as Acinetobacter sp. FQ-44 based on 16S rDNA sequencing, was specifically chosen as the most favorable strain owing to its strong capabilities to (1) promote the growth of rape seedlings (significantly increased root length, shoot length, and fresh weight by 92.60%, 31.00%, and 41.96%, respectively) under gnotobiotic conditions; (2) tolerate up to 1000 mg⋅L-1 Cu and 800 mg⋅L-1 Zn; (3) mobilize the highest concentrations of water-soluble Cu, Zn, Pb, and Fe (16.99, 0.98, 0.08, and 3.03 mg⋅L-1, respectively); and (4) adsorb the greatest quantities of Cu and Zn (7.53 and 6.61 mg⋅g-1 dry cell, respectively). Our findings suggest that Acinetobacter sp. FQ-44 could be exploited for bacteria-assisted phytoextraction. Moreover
-
Karagöz, Alper; Baran, Irmak; Aksu, Neriman; Acar, Sümeyra; Durmaz, Rıza
2014-10-01
Acinetobacter baumannii which is a significant cause of nosocomial infections, increases the rate of morbidity and mortality in health care settings especially in intensive care units (ICUs). The aim of this study was to determine the antibiotic resistance profiles of A.baumannii strains isolated from blood cultures of inpatients from different ICUs, wards and hospital environment and evaluate their clonal relationships and epidemiologic features. A total of 54 A.baumannii strains (47 from the blood cultures and 7 from the hospital environment), identified between 01 January 2012-28 December 2012 at the Clinical Microbiology Laboratory of Ankara Numune Training and Research Hospital, Turkey, were included in the study. Identification of A.baumannii isolates and their antimicrobial [sulbactam-ampicillin (SAM), piperacillin (PIP), piperacillin-tazobactam (TZP), ceftazidime (CFZ), cefoperazone-sulbactam (SCF), cefepime (CEF), imipenem (IMP), meropenem (MER), amikacin (AMK), gentamicin (GEN), netilmicin (NT), ciprofloxacin (CIP), levofloxacin (LVF), tetracycline (TET), tigecycline (TG), colistin (COL), trimethoprim-sulfamethoxazole (SXT)] susceptibility testing were performed by Vitek 2 (bioMérieux, France) system. The clonal relationship between the A.baumannii isolates was analysed by pulsed-field gel electrophoresis (PFGE). In our study colistin, tigecycline and netilmicin were found to be the most effective agents against A.baumannii isolates. All of the clinical isolates (n= 47) were found susceptible to COL, however all were resistant to SAM, PIP, TZP, CEF, IPM, CFZ, MER and CIP. While 1.85%, 14.8%, 14.8%, 16.6%, 59.2% and 22.2% of the isolates were susceptible to SCF, AMK, NT, GEN, TG and SXT, respectively; 1.85%, 1.85%, 9.2%, 16.6%, 38.8% and 27.7% of the isolates were intermediate to SCF, TET, AMK, NT, LVF and TG, respectively. Similarly, all of the environmental A.baumannii isolates (n= 7) were resistant to SAM, PIP, TZP, CFZ, CEF, IPM, MER and CIP, and all
-
Chang, T Y; Chen, C C; Cheng, K M; Chin, C Y; Chen, Y H; Chen, X A; Sun, J R; Young, J J; Chiueh, T S
2017-07-01
We report a facile route for the green synthesis of trimethyl chitosan nitrate-capped silver nanoparticles (TMCN-AgNPs) with positive surface charge. In this synthesis, silver nitrate, glucose, and trimethyl chitosan nitrate (TMCN) were used as silver precursor, reducing agent, and stabilizer, respectively. The reaction was carried out in a stirred basic aqueous medium at room temperature without the use of energy-consuming or expensive equipment. We investigated the effects of the concentrations of NaOH, glucose, and TMCN on the particle size, zeta potential, and formation yield. The AgNPs were characterized by UV-vis spectroscopy, photon correlation spectroscopy, laser Doppler anemometry, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The catalytic activity of the TMCN-AgNPs was studied by the reduction of 4-nitrophenol using NaBH 4 as a reducing agent. We evaluated the antibacterial effects of the TMCN-AgNPs on Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus using the broth microdilution method. The results showed that both gram-positive and gram-negative bacteria were killed by the TMCN-AgNPs at very low concentration (<6.13μg/mL). Moreover, the TMCN-AgNPs also showed high antibacterial activity against clinically isolated multidrug-resistant A. baumannii strains, and the minimum inhibitory concentration (MIC) was ≤12.25μg/mL. Copyright © 2017 Elsevier B.V. All rights reserved.
-
Shakibaie, Mohammad Reza; Azizi, Omid; Shahcheraghi, Fereshteh
2017-07-01
Metallo-β-lactamases (MBLs) such as IMPs are broad-spectrum β-lactamases that inactivate virtually all β-lactam antibiotics including carbapenems. In this study, we investigated the hydrolytic activity, phylogenetic relationship, three dimensional (3D) structure including zinc binding motif of a new IMP variant (IMP-55) identified in a clinical strain of Acinetobacter baumannii (AB). AB strain 56 was isolated from an adult ICU of a teaching hospital in Kerman, Iran. It exhibited MIC 32μg/ml to imipenem and showed MBL activity. Hydrolytic property of the MBL enzyme was measured phenotypically. Presence of bla IMP gene encoded by class 1 integrons was detected by PCR-sequencing. Phylogenetic tree of IMP protein was constructed using the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) and 3D model including zinc binding motif was predicted by bioinformatics softwares. Analysis of IMP sequence led to the identification of a novel IMP-type designated as IMP-55 (GenBank: KU299753.1; UniprotKB: A0A0S2MTX2). Impact in term of hydrolytic activity compared to the closest variants suggested efficient imipenem hydrolysis by this enzyme. Evolutionary distance matrix assessment indicated that IMP-55 protein is not closely related to other A. baumannii IMPs, however, shared 98% homology with Escherichia coli IMP-30 (UniprotKB: A0A0C5PJR0) and Pseudomonas aeruginosa IMP-1 (UniprotKB: Q19KT1). It consisted of five α-helices, ten β-sheets and six loops. A monovalent zinc ion attached to core of enzyme via His95, His97, His157 and Cys176. Multiple amino acid sequence alignments and mutational trajectory with reported IMPs showed 4 amino acid substitutions at positions 12(Phe→Ile), 31(Asp→Glu), 172(Leu→Phe) and 185(Asn→Lys). We suggest that the pleiotropic effect of mutations due to frequent administration of imipenem is responsible for emergence of new IMP variant in our hospitals. Copyright © 2017 Elsevier B.V. All rights reserved.
-
Sun, Daqing; Crowell, Sara A.; Harding, Christian M.; De Silva, P. Malaka; Harrison, Alistair; Fernando, Dinesh M.; Mason, Kevin M.; Santana, Estevan; Loewen, Peter C.; Kumar, Ayush; Liu, Yusen
2016-01-01
Aims Catalase catalyzes the degradation of H2O2. Acinetobacter species have four predicted catalase genes, katA, katE, katG, and katX. The aims of the present study seek to determine which catalase(s) plays a predominant role in determining the resistance to H2O2, and to assess the role of catalase in Acinetobacter virulence. Main Methods Mutants of A. baumannii and A. nosocomialis with deficiencies in katA, katE, katG, and katX were tested for sensitivity to H2O2, either by halo assays or by liquid culture assays. Respiratory burst of neutrophils, in response to A. nosocomialis, was assessed by chemiluminescence to examine the effects of catalase on the production of reactive oxygen species (ROS)1 in neutrophils. Bacterial virulence was assessed using a Galleria mellonella larva infection model. Key findings The capacities of A. baumannii and A. nosocomialis to degrade H2O2 are largely dependent on katE. The resistance of both A. baumannii and A. nosocomialis to H2O2 is primarily determined by the katG gene, although katE also plays a minor role in H2O2 resistance. Bacteria lacking both the katG and katE genes exhibit the highest sensitivity to H2O2. While A. nosocomialis bacteria with katE and/or katG were able to decrease ROS production by neutrophils, these cells also induced a more robust respiratory burst in neutrophils than did cells deficient in both katE and katG. We also found that A. nosocomialis deficient in both katE and katG was more virulent than the wildtype A. nosocomialis strain. Significance Our findings suggest that inhibition of Acinetobacter catalase may help to overcome the resistance of Acinetobacter species to microbicidal H2O2 and facilitate bacterial disinfection. PMID:26860891
-
Suljagić, Vesna; Jevtić, Miodrag; Djordjević, Boban; Romić, Predrag; Ilić, Radoje; Stanković, Nebojsa; Milović, Novak; Novaković, Marijan; Kozarski, Jefta; Roganović, Zoran; Popović, Zoran; Jovelić, Aleksandra
2011-08-01
Acinetobacter spp. has emerged as nosocomial pathogen during the past few decades in hospitals all over the world, but it has increasingly been implicated as a serious nosocomial pathogen in military hospitals. The aim of this study was to analyse and compare the surveillance data on Acinetobacter nosocomial colonization/infection (NCI) collected during the wartime with the data collected in peacetime. We conducted a prospective study of incidence of Acinetobacter spp. colonization/infection. Also, the two nested case-control studies were conducted. The patients with nosocomial infection (cases) were compared with those with nosocomial colonization (controls) during the two different periods, wartime and peacetime. The patients with NCI by Acinetobacter spp. were identified by the case-based surveillance. The surveillance covered all the patients in 6 surgical clinics. During the study periods a total of 166 patients had cultures that grew Acinetobacter spp. and the pooled rates of Acinetobacter spp. colonization and infection were significantly higher in wartime. When patients with NCI in wartime were compared with those with NCI in peacetime significant differences were observed. In the war year, the patients were more significantly males (p < 0.000). In a period of peace, most of the colonization/infections were reported from patients with certain chronic diseases (p = 0.020) and the survival of patients was more significant (p = 0.049). During the peacetime, proportions of Acinetobacter isolates resistent to ciprofloksacin, imipenem and meropenem were significantly higher (p < 0.001). This study provides additional important information about the risk factors of nosocomial Acinetobacter spp. infections in a large cohort of surgical patients. This is also the first study that directly examines epidemiological differences between NCI caused by Acinetobacter spp. during the war and peace period.
-
VEB-1 Extended-Spectrum β-lactamase–producing Acinetobacter baumannii, France1
Coignard, Bruno; Carbonne, Anne; Blanckaert, Karine; Bajolet, Odile; Bernet, Claude; Verdeil, Xavier; Astagneau, Pascal; Desenclos, Jean-Claude; Nordmann, Patrice
2006-01-01
VEB-1 extended-spectrum β-lactamase–producing Acinetobacter baumannii was responsible for an outbreak in hospitals in France. A national alert was triggered in September 2003 when 4 hospitals reported clusters of A. baumannii infection with similar susceptibility profiles. Case definitions and laboratory guidelines were disseminated, and prospective surveillance was implemented; strains were sent to a single laboratory for characterization and typing. From April 2003 through June 2004, 53 hospitals reported 290 cases of A. baumannii infection or colonization; 275 isolates were blaVEB-1-positive and clonally related. Cases were first reported in 5 districts of northern France, then in 10 other districts in 4 regions. Within a region, interhospital spread was associated with patient transfer. In northern France, investigation and control measures led to a reduction of reported cases after January 2004. The national alert enabled early control of new clusters, demonstrating the usefulness of early warning about antimicrobial drug resistance. PMID:16965700
-
2-DE analysis indicates that Acinetobacter baumannii displays a robust and versatile metabolism
Soares, Nelson C; Cabral, Maria P; Parreira, José R; Gayoso, Carmen; Barba, Maria J; Bou, Germán
2009-01-01
Background Acinetobacter baumannii is a nosocomial pathogen that has been associated with outbreak infections in hospitals. Despite increasing awareness about this bacterium, its proteome remains poorly characterised, however recently the complete genome of A. baumannii reference strain ATCC 17978 has been sequenced. Here, we have used 2-DE and MALDI-TOF/TOF approach to characterise the proteome of this strain. Results The membrane and cytoplasmatic protein extracts were analysed separately, these analyses revealed the reproducible presence of 239 and 511 membrane and cytoplamatic protein spots, respectively. MALDI-TOF/TOF characterisation identified a total of 192 protein spots (37 membrane and 155 cytoplasmatic) and revealed that the identified membrane proteins were mainly transport-related proteins, whereas the cytoplasmatic proteins were of diverse nature, although mainly related to metabolic processes. Conclusion This work indicates that A. baumannii has a versatile and robust metabolism and also reveal a number of proteins that may play a key role in the mechanism of drug resistance and virulence. The data obtained complements earlier reports of A. baumannii proteome and provides new tools to increase our knowledge on the protein expression profile of this pathogen. PMID:19785748
-
Moss, C W; Wallace, P L; Hollis, D G; Weaver, R E
1988-03-01
We determined phenotypic characteristics, cellular fatty acid composition, and isoprenoid quinone content of representative strains of CDC groups EO-2, M-5, and M-6, Moraxella (Moraxella) species, Oligella urethralis, Acinetobacter species, and Psychrobacter immobilis. All organisms contained ubiquinone with eight isoprene units as the major isoprenolog, but distinct differences were observed in fatty acid composition. Twenty-eight of the original collection of CDC group EO-2 strains were further identified as P. immobilis, EO-2, or EO-3 by distinctive cellular fatty acid profiles, cellular morphology, and pigment production. The cellular fatty acid compositions of M-5 and M-6 were similar but were clearly different from those of other organisms. The genus Acinetobacter was differentiated from other organisms in the study by small amounts of 2-hydroxydodecanoic acid (2-OH-12:0), and P. immobilis was differentiated by small amounts of decanoic acid (10:0) and a branched-chain 17-carbon acid (i-17:0). All Moraxella species were distinguished by small amounts of decanoic acid (10:0) and the absence of i-17:0. M. bovis, M. nonliquefaciens, and some strains of M. lacunata formed a single fatty acid group, while M. osloensis, M. phenylpyruvica, M. atlantae, and other strains of M. lacunata (M. lacunata II) had species-specific fatty acid profiles. O. urethralis differed from Moraxella species by the presence of large amounts (49%) of cis-vaccenic acid (18:1 omega 7c), small amounts (1%) of 3-hydroxyhexadecanoate (3-OH-16:0), and the absence of 10:0 and 3-hydroxydodecanoate (3-OH-12:0). The combined use of chemical data and a small number of conventional tests permitted rapid identification and differentiation of these organisms from each other and from related organisms.
-
Moss, C W; Wallace, P L; Hollis, D G; Weaver, R E
1988-01-01
We determined phenotypic characteristics, cellular fatty acid composition, and isoprenoid quinone content of representative strains of CDC groups EO-2, M-5, and M-6, Moraxella (Moraxella) species, Oligella urethralis, Acinetobacter species, and Psychrobacter immobilis. All organisms contained ubiquinone with eight isoprene units as the major isoprenolog, but distinct differences were observed in fatty acid composition. Twenty-eight of the original collection of CDC group EO-2 strains were further identified as P. immobilis, EO-2, or EO-3 by distinctive cellular fatty acid profiles, cellular morphology, and pigment production. The cellular fatty acid compositions of M-5 and M-6 were similar but were clearly different from those of other organisms. The genus Acinetobacter was differentiated from other organisms in the study by small amounts of 2-hydroxydodecanoic acid (2-OH-12:0), and P. immobilis was differentiated by small amounts of decanoic acid (10:0) and a branched-chain 17-carbon acid (i-17:0). All Moraxella species were distinguished by small amounts of decanoic acid (10:0) and the absence of i-17:0. M. bovis, M. nonliquefaciens, and some strains of M. lacunata formed a single fatty acid group, while M. osloensis, M. phenylpyruvica, M. atlantae, and other strains of M. lacunata (M. lacunata II) had species-specific fatty acid profiles. O. urethralis differed from Moraxella species by the presence of large amounts (49%) of cis-vaccenic acid (18:1 omega 7c), small amounts (1%) of 3-hydroxyhexadecanoate (3-OH-16:0), and the absence of 10:0 and 3-hydroxydodecanoate (3-OH-12:0). The combined use of chemical data and a small number of conventional tests permitted rapid identification and differentiation of these organisms from each other and from related organisms. Images PMID:3356788
-
Han, Lei; Lei, Jine; Xu, Jiru; Han, Shaoshan
2017-12-01
Acinetobacter baumannii is one of the major threats in clinical infections due to its antibiotic resistance ability. It shows increasing resistance to carbapenems, mainly due to β-lactamase mediated mechanisms. The aim of this study was to investigate carbapenem resistance (CR) profiles and analyze β-lactamases genes composition of clinical A. baumannii strains from a teaching hospital in Xi'an. The resistance patterns to imipenem and meropenem were checked for 51 clinical A. baumannii strains. The existence of 15 β-lactamases genes was detected by polymerase chain reaction (PCR), and the positive genes were sequenced. The correlation between PCR-positive genes and CR phenotype was analyzed using Chi-square test and contingency coefficient. The expressions of PCR-positive genes were investigated. Forty-five out of 51 strains were resistant to imipenem and meropenem. blaTEM, blaOXA-23-like, and blaOXA-51-like were positive among 15 β-lactamases genes, and TEM-1, OXA-23, and OXA-66/69 were their subtypes. TEM and OXA-23-like only showed up in CR isolates, with the occurrence rate of 91.1% and 97.8%, respectively, whereas OXA-51-like appeared in all strains. ISAba1 was present in the upstream of OXA-23-like, but absent from that of OXA-51-like in our strains. OXA-23-like had highest relationship with CR, followed by TEM, but OXA-51-like had no correlation. This was verified by RT-qPCR that the expression was positive for OXA-23 and TEM-1, but negative for OXA-66/-69. A high rate of CR A. baumannii was detected in this study. Coexistence of TEM, OXA-23-like, and OXA-51-like was the primary resistance profile. The expressions of OXA-23-like and TEM genes were closely related with CR, while OXA-51-like had no contribution to the CR phenotype.
-
Kempf, Marie; Abdissa, Alemseged; Diatta, Georges; Trape, Jean-François; Angelakis, Emmanouil; Mediannikov, Oleg; La Scola, Bernard; Raoult, Didier
2012-09-01
Acinetobacter baumannii has previously been detected and genotyped in human body lice. The objectives of this study were to determine the presence of this bacterium in head and body lice collected from healthy individuals in Ethiopia by molecular methods and to characterize the genotype. Human lice from locations at different altitudes in Ethiopia were screened for the presence of Acinetobacter sp by targeting the rpoB gene. Acinetobacter baumannii was detected and genotyped using recA PCR amplification. A total of 115 head and 109 body lice were collected from 134 healthy individuals. Acinetobacter sp were found in 54 head (47%) and 77 body (71%) lice. The recA gene was sequenced for 60 of the Acinetobacter sp and 67% were positive for A. baumannii; genotype 1 was retrieved the most frequently. Our study is the first to show the presence of A. baumannii in human body lice, and also in head lice, in Ethiopia. Copyright © 2012 International Society for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
-
[Multidrug resistance E-ESKAPE strains isolated from blood cultures in patients with cancer].
Velázquez-Acosta, Consuelo; Cornejo-Juárez, Patricia; Volkow-Fernández, Patricia
2018-01-01
To describe the trend of multidrug resistant (MDR) strains isolated from blood in patients with cancer from 2005 to 2015. 33 127 blood cultures were processed by retrospective analysis. Identification and antimicrobial sensitivity were performed through automated methods: WaLK away (Siemens Labora- tory Diagnostics) and BD Phoenix (Becton, Dickinson and Company). Resistant strains were determined according to the minimum inhibitory concentration, following the parameters of the Clinical and Laboratory Standards Institute (CLSI). Of 6 397 isolates, 5 604 (16.9%) were positive; 3 732 (58.4%) Gram- bacilli; 2 355 (36.9%) Gram+ cocci; 179 (2.7%) yeasts, and 126 (1.9%) Gram+ bacilli. Escherichia coli (n=1 591, 24.5%) was the most frequent bacteria, with 652 (41%) strains being extended-spectrum beta-lactamases producers (ESBL); of Enterococcus faecium (n=143, 2.1%), 45 (31.5%) were vancomycin resistant; of Staphylococcus aureus (n=571, 8.7%), 121 (21.2%) methicillin resistant (MRSA); of Klebsiella pneumoniae (n=367, 5.6%), 41 (11.2%) ESBL; of Acinetobacter baumanii (n=96, 1.4%), 23 (24%) MDR, and of Pseudomonas aeruginosa (n=384, 5.6%), 43 (11.2%) MDR. MDR strains were significantly more frequent in patients with hematological malignancies, compared to those with solid tumors: MRSA (OR=4.48, 95%CI 2.9-6.8), ESBL E. coli(OR=1.3, 95%CI 1.10-1.65) and MDR Acinetobacter baumanii (OR=3.2, 95%CI 1.2-8.3). We observed significantly higher isolations of E-ESPAKE MDR strains in patients with hematological malignancies.
-
AbuBakar, Sazaly; Cerqueira, Gustavo Maia; Al-Haroni, Mohammed; Pang, Sui Ping
2015-01-01
Acinetobacter baumannii has emerged as a notorious multidrug-resistant pathogen, and development of novel control measures is of the utmost importance. Understanding the factors that play a role in drug resistance may contribute to the identification of novel therapeutic targets. Pili are essential for A. baumannii adherence to and biofilm formation on abiotic surfaces as well as virulence. In the present study, we found that biofilm formation was significantly induced in an imipenem-resistant (Impr) strain treated with a subinhibitory concentration of antibiotic compared to that in an untreated control and an imipenem-susceptible (Imps) isolate. Using microarray and quantitative PCR analyses, we observed that several genes responsible for the synthesis of type IV pili were significantly upregulated in the Impr but not in the Imps isolate. Notably, this finding is corroborated by an increase in the motility of the Impr strain. Our results suggest that the ability to overproduce colonization factors in response to imipenem treatment confers biological advantage to A. baumannii and may contribute to clinical success. PMID:26666943
-
Karumathil, Deepti Prasad; Yin, Hsin-Bai; Kollanoor-Johny, Anup; Venkitanarayanan, Kumar
2014-01-01
Acinetobacter baumannii is a multidrug resistant pathogen capable of causing a wide spectrum of clinical conditions in humans. Acinetobacter spp. is ubiquitously found in different water sources. Chlorine being the most commonly used disinfectant in water, the study investigated the effect of chlorine on the survival of A. baumannii in water and transcription of genes conferring antibiotic resistance. Eight clinical isolates of A. baumannii, including a fatal meningitis isolate (ATCC 17978) (~108 CFU/mL) were separately exposed to free chlorine concentrations (0.2, 1, 2, 3 and 4 ppm) with a contact time of 30, 60, 90 and 120 second. The surviving pathogen counts at each specified contact time were determined using broth dilution assay. In addition, real-time quantitative PCR (RT-qPCR) analysis of the antibiotic resistance genes (efflux pump genes and those encoding resistance to specific antibiotics) of three selected A. baumannii strains following exposure to chlorine was performed. Results revealed that all eight A. baumannii isolates survived the tested chlorine levels during all exposure times (p > 0.05). Additionally, there was an up-regulation of all or some of the antibiotic resistance genes in A. baumannii, indicating a chlorine-associated induction of antibiotic resistance in the pathogen. PMID:24514427
-
Reinhart, Alexandria A.; Alamneh, Yonas A.; Pucci, Michael J.; Si, Yuanzheng; Abu-Taleb, Rania; Shearer, Jonathan P.; Demons, Samandra T.; Tyner, Stuart D.; Lister, Troy
2017-01-01
ABSTRACT Acinetobacter baumannii is responsible for 10% of all nosocomial infections and has >50% mortality rates when causing ventilator-associated pneumonia. In this proof-of-concept study, we evaluated SPR741, an antibiotic adjuvant that permeabilizes the Gram-negative membrane, in combination with rifampin against AB5075, an extensively drug-resistant (XDR) A. baumannii strain. In standard in vitro assays and in a murine pulmonary model, we found that this drug combination can significantly reduce bacterial burden and promote animal survival despite an aggressive infection. PMID:28947471
-
21 CFR 866.3010 - Acinetobacter calcoaceticus serological reagents.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Acinetobacter calcoaceticus serological reagents. 866.3010 Section 866.3010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3010...
-
21 CFR 866.3010 - Acinetobacter calcoaceticus serological reagents.
Code of Federal Regulations, 2014 CFR
2014-04-01
... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Acinetobacter calcoaceticus serological reagents. 866.3010 Section 866.3010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3010...
-
21 CFR 866.3010 - Acinetobacter calcoaceticus serological reagents.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Acinetobacter calcoaceticus serological reagents. 866.3010 Section 866.3010 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3010...
-
Mushtaq, Shazad; Vickers, Anna; Woodford, Neil; Livermore, David M
2017-06-01
Several diazabicyclooctanes (DBOs) are under development as inhibitors of class A and C β-lactamases. Inhibition of OXA (class D) carbapenemases is variable, with those of Acinetobacter spp. remaining notably resistant. We describe a novel DBO, WCK 4234 (Wockhardt), with distinctive activity against OXA carbapenemases. MICs of imipenem and meropenem were determined by CLSI agar dilution with WCK 4234 added at 4 or 8 mg/L. Test organisms were clinical Enterobacteriaceae, Acinetobacter baumannii and Pseudomonas aeruginosa with carbapenemases or carbapenem resistance via porin loss plus AmpC or ESBL activity. AmpC mutants were also tested. WCK 4234, which lacked direct antibacterial activity, strongly potentiated imipenem and meropenem against Enterobacteriaceae with OXA-48/OXA-181 or KPC enzymes, or with combinations of impermeability and AmpC or ESBL activity, with MICs reduced to ≤2 mg/L in almost all cases. Carbapenems likewise were potentiated against P. aeruginosa ( n = 2) with OXA-181 enzyme, with MICs reduced from 64-128 to 2-8 mg/L and against A. baumannii with OXA carbapenemases, particularly OXA-23 or hyperproduced OXA-51, with MICs reduced to ≤2 mg/L for 9/10 acinetobacters with OXA-23 enzyme. Carbapenems were not potentiated against Enterobacteriaceae or non-fermenters with metallo-β-lactamases. WCK 4234 distinctively overcame resistance mediated by OXA-type carbapenemases, including those of A. baumannii . It behaved similarly to other DBOs against strains with KPC carbapenemases or combinations of impermeability and ESBL or AmpC activity. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
-
Aly, M M; Abu Alsoud, N M; Elrobh, M S; Al Johani, S M; Balkhy, H H
2016-11-01
The prevalence of carbapenem-resistant Acinetobacter baumannii in Saudi Arabia and their resistance genetic mechanisms are yet to be identified. We studied the prevalence and genetic diversity of extended-spectrum beta-lactamase genes, particularly the PER-1 gene, among carbapenem-resistant A. baumannii strains from patients at a tertiary care hospital in Riyadh, Saudi Arabia between 2006 and 2014. Fresh subcultured samples were tested for antimicrobial susceptibility minimum inhibitory concentration (MIC). Total genomic DNA was extracted from each isolate and further used for polymerase chain reaction (PCR) genotyping, sequence-based typing (SBT) of PER-1 and OXA-51-like gene, and multilocus sequence typing (MLST) of positive isolates. Randomly selected clinical isolates (n = 100) were subjected to MLST. A total of 503 isolates were characterized as multidrug-resistant (MDR) using the MIC. Isolates were further PCR tested for bla -TEM and bla -PER-1 resistance genes (n = 503). The genotyping results showed that 68/503 (14 %) isolates were positive to bla TEM. The genotyping results of PER-1-like genes showed that 384/503 (76.3 %) were positive among MDR Acinetobacter isolates. Based on SBT, the majority of these isolates were clustered into three main groups including isolates harboring PER-1: AB11 (bla -PER-1 ), isolate AB16 (bla -PER-1 ), and, finally, the plasmid pAB154 (bla -PER-7 ). Remarkably, many isolates were concealing the PER-1 gene and harboring the TEM resistance genes as well. MLST results for selected isolates (n = 100) identified four main sequence types (STs: 2, 19, 20, and 25) and four novel isolates (ST 486-489). We report 76.3 % prevalence of the PER-1 resistance gene among Acinetobacter clinical isolates from Riyadh, Saudi Arabia. Further work is needed to explore the clinical risks and patient outcome with such resistance related to healthcare-associated infections and investigate the genetic and molecular mechanisms that confer the MDR
-
Matsui, Mari; Suzuki, Masato; Suzuki, Masahiro; Yatsuyanagi, Jun; Watahiki, Masanori; Hiraki, Yoichi; Kawano, Fumio; Tsutsui, Atsuko; Shibayama, Keigo; Suzuki, Satowa
2018-02-01
Multidrug-resistant (MDR) Acinetobacter spp. have been globally disseminated in association with the successful clonal lineage Acinetobacter baumannii international clone II (IC II). Because the prevalence of MDR Acinetobacter spp. in Japan remains very low, we characterized all Acinetobacter spp. ( n = 866) from 76 hospitals between October 2012 and March 2013 to describe the entire molecular epidemiology of Acinetobacter spp. The most prevalent species was A. baumannii ( n = 645; 74.5%), with A. baumannii IC II ( n = 245) accounting for 28.3% of the total. Meropenem-resistant isolates accounted for 2.0% ( n = 17) and carried IS Aba1-bla OXA-23-like ( n = 10), bla IMP ( n = 4), or IS Aba1-bla OXA-51-like ( n = 3). Multilocus sequence typing of 110 representative A. baumannii isolates revealed the considerable prevalence of domestic sequence types (STs). A. baumannii IC II isolates were divided into the domestic sequence type 469 (ST469) ( n = 18) and the globally disseminated STs ST208 ( n = 14) and ST219 ( n = 4). ST469 isolates were susceptible to more antimicrobial agents, while ST208 and ST219 overproduced the intrinsic AmpC β-lactamase. A. baumannii IC II and some A. baumannii non-IC II STs (e.g., ST149 and ST246) were associated with fluoroquinolone resistance. This study revealed that carbapenem-susceptible A. baumannii IC II was moderately disseminated in Japan. The low prevalence of acquired carbapenemase genes and presence of domestic STs could contribute to the low prevalence of MDR A. baumannii A similar epidemiology might have appeared before the global dissemination of MDR epidemic lineages. In addition, fluoroquinolone resistance associated with A. baumannii IC II may provide insight into the significance of A. baumannii epidemic clones. Copyright © 2018 American Society for Microbiology.
-
Shabtai, Y
1990-04-01
The production of two extracellular capsular heteropolysaccharides by two different Acinetobacter strains has been studied in separate controlled fermentation processes with a view to their industrial applications as specific dispersing agents. The first, emulsan, is an extracellular polyanionic amphipathic heteropolysaccharide (MW 10(6) D) made by A. calcoaceticus RAG-1. It forms and stabilizes oil in water emulsions. The other, biodispersan (PS-A2), is another extracellular zwitterionic heteropolysaccharide (MW 51 kD) made by A. calcoaceticus A2. This polysaccharide disperses big solid limestone granules forming micron-size water suspension. Both polysaccharides are synthesized within the cells, exported to their outer surface to form an extracellular cell-associated capsule and released subsequently into the growth medium. The polymers were produced in a computer-controlled fed-batch intensively aerated fermentation process. A commercially available and cheap fatty acids mixture (soap stock oil) served as the carbon source, and was fed in coordination with the required nitrogen. The coordinated feed of carbon and nitrogen was operated on the basis of two metabolic correlations: The first correlation related the cell protein produced and the ammonium nitrogen consumed with the outcoming coeffients of 24 and 21 mM NH3/g protein for the emulsan and the biodispersan fermentations respectively. The second correlation linked the consumption of the fatty acids with that of the nitrogen source dictating the appropriate C/N ratio of the feed into the operating fermentor. These ratios were 7.7 g C/g N for the emulsan fermentation and 8.5 gC/g N in the case of the biodispersan production process.(ABSTRACT TRUNCATED AT 250 WORDS)
-
Grochowalska, Aneta; Kozioł-Montewka, Maria; Sobieszczańska, Anna
2017-06-12
Introduction. Multi-resistant Acinetobacter baumannii isolated from patients has become one of the most hazardous pathogens in health care settings. The aim of the study was to analyze pneumonia caused by Acinetobacter baumannii in patients hospitalized because of exacerbation of chronic obstructive pulmonary diseases (COPD), who were admitted to the Pulmonology Ward of the Masovian Specialistic Hospital in Radom (MSS). The incidence and drug sensitivity of these non-fermenting rods were evaluated, and compliance with antimicrobial procedure with the algorithm of the guidelines in applicable recommendations, was estimated. This should result in determining the local patterns of resistance and verifying therapeutic procedures in accordance with the assumptions of hospital antibiotic policy. In addition, the study examined the effectiveness of empiric and targeted therapy according to the clinical condition of the patient, and the eradication of A. baumannii, in comparison with the aggravating factors of the patient. Materials and Method. The retrospective study included 90 patients with exacerbation of COPD whose etiological factor of infection was A. baumannii, hospitalized in the Department of Pulmonology (MSS) in 2012-2016. Results. Studies were conducted on 90 patients with COPD exacerbation from which A. baumannii was isolated. Co-infections with other bacterial species among 41 patients were additionally noted. The majority of A. baumannii strains showed a high resistance (90%) to fluoroquinolones, ceftazidime, piperacillin/tazobactam. For strains causing a co-infection, drug resistance was successively 44-56%, 44%, 44%. All of patients received empirical therapy. The most commonly used drug was amoxicillin with a clavulanic acid, often combined with fluoroquinolone. This type of therapy was effective among 10% of patients. The mortality in this group was determined at 29%. Among 79% of patients with COPD, a targeted therapy was performed which proved to be
-
Souto, Renata; Silva-Boghossian, Carina M; Colombo, Ana Paula Vieira
2014-01-01
P. aeruginosa and Acinetobacter spp. are important pathogens associated with late nosocomial pneumonia in hospitalized and institutionalized individuals. The oral cavity may be a major source of these respiratory pathogens, particularly in the presence of poor oral hygiene and periodontal infection. This study investigated the prevalence of P. aeruginosa and Acinetobacter spp. in subgingival biofilm and saliva of subjects with periodontal disease or health. Samples were obtained from 55 periodontally healthy (PH) and 169 chronic periodontitis (CP) patients. DNA was obtained from the samples and detection of P. aeruginosa and Acinetobacter spp. was carried out by multiplex and nested PCR. P. aeruginosa and Acinetobacter spp. were detected in 40% and 45% of all samples, respectively. No significant differences in the distribution of these microorganisms between men and women, subgingival biofilm and saliva samples, patients ≤ 35 and > 35 years of age, and smokers and non-smokers were observed regardless periodontal status (p > 0.05). In contrast, the frequencies of P. aeruginosa and Acinetobacter spp. in saliva and biofilm samples were significantly greater in CP than PH patients (p < 0.01). Smokers presenting P. aeruginosa and high frequencies of supragingival plaque were more likely to present CP than PH. P. aeruginosa and Acinetobacter spp. are frequently detected in the oral microbiota of CP. Poor oral hygiene, smoking and the presence of P. aeruginosa are strongly associated with periodontitis.
-
Souto, Renata; Silva-Boghossian, Carina M.; Colombo, Ana Paula Vieira
2014-01-01
P. aeruginosa and Acinetobacter spp. are important pathogens associated with late nosocomial pneumonia in hospitalized and institutionalized individuals. The oral cavity may be a major source of these respiratory pathogens, particularly in the presence of poor oral hygiene and periodontal infection. This study investigated the prevalence of P. aeruginosa and Acinetobacter spp. in subgingival biofilm and saliva of subjects with periodontal disease or health. Samples were obtained from 55 periodontally healthy (PH) and 169 chronic periodontitis (CP) patients. DNA was obtained from the samples and detection of P. aeruginosa and Acinetobacter spp. was carried out by multiplex and nested PCR. P. aeruginosa and Acinetobacter spp. were detected in 40% and 45% of all samples, respectively. No significant differences in the distribution of these microorganisms between men and women, subgingival biofilm and saliva samples, patients ≤ 35 and > 35 years of age, and smokers and non-smokers were observed regardless periodontal status (p > 0.05). In contrast, the frequencies of P. aeruginosa and Acinetobacter spp. in saliva and biofilm samples were significantly greater in CP than PH patients (p < 0.01). Smokers presenting P. aeruginosa and high frequencies of supragingival plaque were more likely to present CP than PH. P. aeruginosa and Acinetobacter spp. are frequently detected in the oral microbiota of CP. Poor oral hygiene, smoking and the presence of P. aeruginosa are strongly associated with periodontitis. PMID:25242933
-
Machado, Diana; Antunes, Jéssica; Simões, Ana; Perdigão, João; Couto, Isabel; McCusker, Matthew; Martins, Marta; Portugal, Isabel; Pacheco, Teresa; Batista, Judite; Toscano, Cristina; Viveiros, Miguel
2018-06-01
The mechanisms underlying colistin heteroresistance in Acinetobacter baumannii are not fully understood. Here, we investigated the role of efflux in colistin-heteroresistant populations of a multidrug-resistant (MDR) A. baumannii clinical isolate. Three colistin-resistant A. baumannii strain variants isolated from the same clinical sample were studied for the presence of heteroresistance to colistin by drug susceptibility testing, genotyping and drug resistance target mutation analysis. The existence of active efflux was studied by synergism assays with efflux inhibitors, real-time efflux activity measurements and analysis of the mRNA transcriptional levels of selected efflux pump genes in response to colistin. All of the strain variants belong to the ST218, clonal complex 92, international clonal lineage II. Different colistin susceptibility levels were observed among the three strain variants, indicating that colistin-heteroresistant subpopulations were being selected upon exposure to colistin. No mutations were found in the genes lpxACD and pmrAB, which are associated with colistin resistance. The results showed the existence of synergistic interactions between efflux inhibitors and colistin and ethidium bromide. Real-time efflux assays demonstrated that the three strain variants had increased efflux activity that could be inhibited in the presence of the inhibitors. The efflux pump genes adeB, adeJ, adeG, craA, amvA, abeS and abeM were found to be overexpressed in the strain variants in response to colistin exposure. This study shows that efflux activity contributes to colistin heteroresistance in an MDR A. baumannii clinical isolate. The use of efflux inhibitors as adjuvants of the therapy can resensitize A. baumannii to colistin and prevent the emergence of drug resistance.
-
Janahiraman, Sivakami; Aziz, Muhammad Nazri; Hoo, Fan Kee; P’ng, Hon Shen; Boo, Yang Liang; Ramachandran, Vasudevan; Shamsuddin, Ahmad Fuad
2015-01-01
Backgrounds & Objective: Antimicrobial resistance is a major health problem worldwide in hospitals. The main contributing factors are exposures to broad-spectrum antimicrobials and cross-infections. Understanding the extent and type of antimicrobial use in tertiary care hospitals will aid in developing national antimicrobial stewardship priorities. Methods: In this study, we have analyzed the antimicrobial agents’ usage for acquisition of multidrug resistant using retrospective, cross-sectional, single-centre study in a multidisciplinary ICU at tertiary care hospital. Results: Acinetobacter baumannii (ACB) was isolated in various specimens from 662 patients. From these, 136 patients who were diagnosed with Ventilator-associated pneumonia (VAP) caused by ACB were included into the study. In our study, MDR strain accounts for 51% of all VAP cases caused by ACB. The development of ACB VAP were 10.5 + 6.4 days for MDR strains compared to susceptible organism (7.8 + 4.5 days) and had significantly longer ICU stay. Conclusion: The study concludes that prudent use of antimicrobial agents is important to reduce acquisition of MDR ACB. PMID:26870101
-
Kalscheuer, Rainer; Stöveken, Tim; Luftmann, Heinrich; Malkus, Ursula; Reichelt, Rudolf; Steinbüchel, Alexander
2006-01-01
Wax esters are esters of long-chain fatty acids and long-chain fatty alcohols which are of considerable commercial importance and are produced on a scale of 3 million tons per year. The oil from the jojoba plant (Simmondsia chinensis) is the main biological source of wax esters. Although it has a multitude of potential applications, the use of jojoba oil is restricted, due to its high price. In this study, we describe the establishment of heterologous wax ester biosynthesis in a recombinant Escherichia coli strain by coexpression of a fatty alcohol-producing bifunctional acyl-coenzyme A reductase from the jojoba plant and a bacterial wax ester synthase from Acinetobacter baylyi strain ADP1, catalyzing the esterification of fatty alcohols and coenzyme A thioesters of fatty acids. In the presence of oleate, jojoba oil-like wax esters such as palmityl oleate, palmityl palmitoleate, and oleyl oleate were produced, amounting to up to ca. 1% of the cellular dry weight. In addition to wax esters, fatty acid butyl esters were unexpectedly observed in the presence of oleate. The latter could be attributed to solvent residues of 1-butanol present in the medium component, Bacto tryptone. Neutral lipids produced in recombinant E. coli were accumulated as intracytoplasmic inclusions, demonstrating that the formation and structural integrity of bacterial lipid bodies do not require specific structural proteins. This is the first report on substantial biosynthesis and accumulation of neutral lipids in E. coli, which might open new perspectives for the biotechnological production of cheap jojoba oil equivalents from inexpensive resources employing recombinant microorganisms. PMID:16461689
-
Kalscheuer, Rainer; Stöveken, Tim; Luftmann, Heinrich; Malkus, Ursula; Reichelt, Rudolf; Steinbüchel, Alexander
2006-02-01
Wax esters are esters of long-chain fatty acids and long-chain fatty alcohols which are of considerable commercial importance and are produced on a scale of 3 million tons per year. The oil from the jojoba plant (Simmondsia chinensis) is the main biological source of wax esters. Although it has a multitude of potential applications, the use of jojoba oil is restricted, due to its high price. In this study, we describe the establishment of heterologous wax ester biosynthesis in a recombinant Escherichia coli strain by coexpression of a fatty alcohol-producing bifunctional acyl-coenzyme A reductase from the jojoba plant and a bacterial wax ester synthase from Acinetobacter baylyi strain ADP1, catalyzing the esterification of fatty alcohols and coenzyme A thioesters of fatty acids. In the presence of oleate, jojoba oil-like wax esters such as palmityl oleate, palmityl palmitoleate, and oleyl oleate were produced, amounting to up to ca. 1% of the cellular dry weight. In addition to wax esters, fatty acid butyl esters were unexpectedly observed in the presence of oleate. The latter could be attributed to solvent residues of 1-butanol present in the medium component, Bacto tryptone. Neutral lipids produced in recombinant E. coli were accumulated as intracytoplasmic inclusions, demonstrating that the formation and structural integrity of bacterial lipid bodies do not require specific structural proteins. This is the first report on substantial biosynthesis and accumulation of neutral lipids in E. coli, which might open new perspectives for the biotechnological production of cheap jojoba oil equivalents from inexpensive resources employing recombinant microorganisms.
-
Tiwari, Vishvanath; Tiwari, Deepika; Patel, Varsha; Tiwari, Monalisa
2017-09-01
Acinetobacter baumannii, opportunistic nosocomial pathogen, increases gradually in the clinical setup. The high level of resistance mechanisms acquired by these bacteria makes their eradication difficult and biofilm formation is one of them. Biofilm comprises of closely packed bacterial population crowded together by extra-cellular matrix (ECM). ECM contains bacterial secreted polymers such as exopolysaccharides (EPS), proteins and extracellular-DNA (e-DNA) and rarely amyloidogenic proteins. Biofilm offers protection of underlying bacterial population against chemotherapeutic agents and host immune system. Therefore, present efforts are focused to find a novel therapeutic that targets biofilm-associated infections. Plants are used as a natural therapeutic for numerous ailments. In order to find an alternative of the available antibacterial drugs, we have focused on the natural herbal active compounds. In this study, we have extracted active compounds from various medicinal plants and screened its anti-biofilm activity against carbapenem resistant strain of A. baumannii. Results showed that polar extract of kiwi (Actinidia deliciosa) and clove (Syzygium aromaticum) exhibit effective anti-biofilm activity. These two plants were also used for their phytochemical screening and TLC profiling to find out the constituting secondary metabolites. Actinidia deliciosa extract contains an alkaloid (sanquinarine) as well as a flavonoid (hydroxyflavone). Anti-biofilm effect of this extract on the ECM of A. baumannii showed that it reduces EPS, protein and eDNA contents in the ECM. Proteins of ECM have also shown to form amyloid like structure, which was evident from its interaction with the Congo Red. CFU counting after Actinidia deliciosa extract treatment also supported the results. Therefore, it can be concluded that polar extract of A. deliciosa can be used to find suitable alternative therapeutic to control biofilm formation by carbapenem resistant strain of
-
Zurawski, Daniel V; Reinhart, Alexandria A; Alamneh, Yonas A; Pucci, Michael J; Si, Yuanzheng; Abu-Taleb, Rania; Shearer, Jonathan P; Demons, Samandra T; Tyner, Stuart D; Lister, Troy
2017-12-01
Acinetobacter baumannii is responsible for 10% of all nosocomial infections and has >50% mortality rates when causing ventilator-associated pneumonia. In this proof-of-concept study, we evaluated SPR741, an antibiotic adjuvant that permeabilizes the Gram-negative membrane, in combination with rifampin against AB5075, an extensively drug-resistant (XDR) A. baumannii strain. In standard in vitro assays and in a murine pulmonary model, we found that this drug combination can significantly reduce bacterial burden and promote animal survival despite an aggressive infection. Copyright © 2017 Zurawski et al.
-
Severe Acinetobacter baumannii Sepsis Is Associated with Elevation of Pentraxin 3
Ketter, Patrick M.; Guentzel, M. Neal; Schaffer, Beverly; Herzig, Maryanne; Wu, Xiaowu; Montgomery, Robbie K.; Parida, Bijaya K.; Fedyk, Chriselda G.; Yu, Jieh-Juen; Jorgensen, James; Chambers, James P.; Cap, Andrew P.
2014-01-01
Multidrug-resistant Acinetobacter baumannii is among the most prevalent bacterial pathogens associated with trauma-related wound and bloodstream infections. Although septic shock and disseminated intravascular coagulation have been reported following fulminant A. baumannii sepsis, little is known about the protective host immune response to this pathogen. In this study, we examined the role of PTX3, a soluble pattern recognition receptor with reported antimicrobial properties and stored within neutrophil granules. PTX3 production by murine J774a.1 macrophages was assessed following challenge with A. baumannii strains ATCC 19606 and clinical isolates (CI) 77, 78, 79, 80, and 86. Interestingly, only CI strains 79, 80, and 86 induced PTX3 synthesis in murine J774a.1 macrophages, with greatest production observed following CI 79 and 86 challenge. Subsequently, C57BL/6 mice were challenged intraperitoneally with CI 77 and 79 to assess the role of PTX3 in vivo. A. baumannii strain CI 79 exhibited significantly (P < 0.0005) increased mortality, with an approximate 50% lethal dose (LD50) of 105 CFU, while an equivalent dose of CI 77 exhibited no mortality. Plasma leukocyte chemokines (KC, MCP-1, and RANTES) and myeloperoxidase activity were also significantly elevated following challenge with CI 79, indicating neutrophil recruitment/activation associated with significant elevation in serum PTX3 levels. Furthermore, 10-fold-greater PTX3 levels were observed in mouse serum 12 h postchallenge, comparing CI 79 to CI 77 (1,561 ng/ml versus 145 ng/ml), with concomitant severe pathology (liver and spleen) and coagulopathy. Together, these results suggest that elevation of PTX3 is associated with fulminant disease during A. baumannii sepsis. PMID:25001601
-
Li, Ruijing; Ning, Xun-an; Sun, Jian; Wang, Yujie; Liang, Jieying; Lin, Meiqing; Zhang, Yaping
2015-10-01
The strain Acinetobacter baumannii YNWH 226 was utilized to degrade Congo red (CR) under aerobic conditions. CR was employed as the sole carbon source to produce extracellular polymeric substances (EPS) used as potent bioflocculants in this strain. A total of 98.62% CR was removed during the 48-h decoloration experiments using CR (100 mg/L). A total of 83% bioadsorption and 65% biodegradation were responsible for the decoloration and degradation of CR through the strain. The bioflocculant showed high flocculation activity and dewaterability on textile dyeing sludge. A maximum flocculation of 78.62% with a minimum SBF of 3.07×10(9) s(2)/g and a CST of 58.4 s were achieved. We investigated the internal relationship between the decolorization efficiency of YNWH 226 and the flocculation activity and dewatering capacity of its EPS. The components and structure of the EPS highly influenced the decolorization efficiency of CR and the flocculation activity and dewatering capacity on sludge. Copyright © 2015 Elsevier Ltd. All rights reserved.
-
Mahamad Maifiah, Mohd Hafidz; Cheah, Soon-Ee; Johnson, Matthew D.; Han, Mei-Ling; Boyce, John D.; Thamlikitkul, Visanu; Forrest, Alan; Kaye, Keith S.; Hertzog, Paul; Purcell, Anthony W.; Song, Jiangning; Velkov, Tony; Creek, Darren J.; Li, Jian
2016-01-01
Multidrug-resistant Acinetobacter baumannii presents a global medical crisis and polymyxins are used as the last-line therapy. This study aimed to identify metabolic differences between polymyxin-susceptible and polymyxin-resistant A. baumannii using untargeted metabolomics. The metabolome of each A. baumannii strain was measured using liquid chromatography-mass spectrometry. Multivariate and univariate statistics and pathway analyses were employed to elucidate metabolic differences between the polymyxin-susceptible and -resistant A. baumannii strains. Significant differences were identified between the metabolic profiles of the polymyxin-susceptible and -resistant A. baumannii strains. The lipopolysaccharide (LPS) deficient, polymyxin-resistant 19606R showed perturbation in specific amino acid and carbohydrate metabolites, particularly pentose phosphate pathway (PPP) and tricarboxylic acid (TCA) cycle intermediates. Levels of nucleotides were lower in the LPS-deficient 19606R. Furthermore, 19606R exhibited a shift in its glycerophospholipid profile towards increased abundance of short-chain lipids compared to the parent polymyxin-susceptible ATCC 19606. In contrast, in a pair of clinical isolates 03–149.1 (polymyxin-susceptible) and 03–149.2 (polymyxin-resistant, due to modification of lipid A), minor metabolic differences were identified. Notably, peptidoglycan biosynthesis metabolites were significantly depleted in both of the aforementioned polymyxin-resistant strains. This is the first comparative untargeted metabolomics study to show substantial differences in the metabolic profiles of the polymyxin-susceptible and -resistant A. baumannii. PMID:26924392
-
Maifiah, Mohd Hafidz Mahamad; Cheah, Soon-Ee; Johnson, Matthew D; Han, Mei-Ling; Boyce, John D; Thamlikitkul, Visanu; Forrest, Alan; Kaye, Keith S; Hertzog, Paul; Purcell, Anthony W; Song, Jiangning; Velkov, Tony; Creek, Darren J; Li, Jian
2016-02-29
Multidrug-resistant Acinetobacter baumannii presents a global medical crisis and polymyxins are used as the last-line therapy. This study aimed to identify metabolic differences between polymyxin-susceptible and polymyxin-resistant A. baumannii using untargeted metabolomics. The metabolome of each A. baumannii strain was measured using liquid chromatography-mass spectrometry. Multivariate and univariate statistics and pathway analyses were employed to elucidate metabolic differences between the polymyxin-susceptible and -resistant A. baumannii strains. Significant differences were identified between the metabolic profiles of the polymyxin-susceptible and -resistant A. baumannii strains. The lipopolysaccharide (LPS) deficient, polymyxin-resistant 19606R showed perturbation in specific amino acid and carbohydrate metabolites, particularly pentose phosphate pathway (PPP) and tricarboxylic acid (TCA) cycle intermediates. Levels of nucleotides were lower in the LPS-deficient 19606R. Furthermore, 19606R exhibited a shift in its glycerophospholipid profile towards increased abundance of short-chain lipids compared to the parent polymyxin-susceptible ATCC 19606. In contrast, in a pair of clinical isolates 03-149.1 (polymyxin-susceptible) and 03-149.2 (polymyxin-resistant, due to modification of lipid A), minor metabolic differences were identified. Notably, peptidoglycan biosynthesis metabolites were significantly depleted in both of the aforementioned polymyxin-resistant strains. This is the first comparative untargeted metabolomics study to show substantial differences in the metabolic profiles of the polymyxin-susceptible and -resistant A. baumannii.
-
Dhabaan, Ghulam Nasser; AbuBakar, Sazaly; Cerqueira, Gustavo Maia; Al-Haroni, Mohammed; Pang, Sui Ping; Hassan, Hamimah
2015-12-14
Acinetobacter baumannii has emerged as a notorious multidrug-resistant pathogen, and development of novel control measures is of the utmost importance. Understanding the factors that play a role in drug resistance may contribute to the identification of novel therapeutic targets. Pili are essential for A. baumannii adherence to and biofilm formation on abiotic surfaces as well as virulence. In the present study, we found that biofilm formation was significantly induced in an imipenem-resistant (Imp(r)) strain treated with a subinhibitory concentration of antibiotic compared to that in an untreated control and an imipenem-susceptible (Imp(s)) isolate. Using microarray and quantitative PCR analyses, we observed that several genes responsible for the synthesis of type IV pili were significantly upregulated in the Imp(r) but not in the Imp(s) isolate. Notably, this finding is corroborated by an increase in the motility of the Imp(r) strain. Our results suggest that the ability to overproduce colonization factors in response to imipenem treatment confers biological advantage to A. baumannii and may contribute to clinical success. Copyright © 2016, American Society for Microbiology. All Rights Reserved.
-
Genetic transformation assays for identification of strains of Moraxella urethralis.
Juni, E
1977-01-01
Studies of 31 strains of Moraxella urethralis have shown that 20 of them are competent for genetic transformation. This finding has led to the development of transformation assays for identification of newly isolated strains of this organism. Crude deoxyribonucleic acid (DNA) samples from all strains of M. urethralis readily transform auxotrophic mutants of competent strains to prototrophy, whereas DNA samples from unrelated bacteria such as Acinetobacter, Moraxella, and Neisseria species uniformly fail to elicit positive transformation of mutant tester strains. One of the competent strains of M. urethralis investigated is a naturally occurring mutant defective in its ability to utilize citrate as a carbon and energy source. DNA samples from 29 of the 30 remaining strains of utilization; the one nonreacting strain is citrate negative and probably possesses the same genetic lesion as the citrate-negative mutant. Three organisms originally identified as strains of M. urethralis, because of their phenotypic properties, are probably incorrectly designated, since DNA samples from these strains failed to transform any of the tester mutant strains used in the present study. The transformation assay for M. urethralis is very simple and can be performed readily in a clinical laboratory. The entire procedure can be carried out in less than 24 h. Images PMID:845247
-
Miyasaki, Yoko; Rabenstein, John D; Rhea, Joshua; Crouch, Marie-Laure; Mocek, Ulla M; Kittell, Patricia Emmett; Morgan, Margie A; Nichols, Wesley Stephen; Van Benschoten, M M; Hardy, William David; Liu, George Y
2013-01-01
The number of fully active antibiotic options that treat nosocomial infections due to multidrug-resistant Acinetobacter baumannii (A. baumannii) is extremely limited. Magnolia officinalis, Mahonia bealei, Rabdosia rubescens, Rosa rugosa, Rubus chingii, Scutellaria baicalensis, and Terminalia chebula plant extracts were previously shown to have growth inhibitory activity against a multidrug-resistant clinical strain of A. baumannii. In this study, the compounds responsible for their antimicrobial activity were identified by fractionating each plant extract using high performance liquid chromatography, and determining the antimicrobial activity of each fraction against A. baumannii. The chemical structures of the fractions inhibiting >40% of the bacterial growth were elucidated by liquid chromatography/mass spectrometry analysis and nuclear magnetic resonance spectroscopy. The six most active compounds were identified as: ellagic acid in Rosa rugosa; norwogonin in Scutellaria baicalensis; and chebulagic acid, chebulinic acid, corilagin, and terchebulin in Terminalia chebula. The most potent compound was identified as norwogonin with a minimum inhibitory concentration of 128 µg/mL, and minimum bactericidal concentration of 256 µg/mL against clinically relevant strains of A. baumannii. Combination studies of norwogonin with ten anti-Gram negative bacterial agents demonstrated that norwogonin did not enhance the antimicrobial activity of the synthetic antibiotics chosen for this study. In conclusion, of all identified antimicrobial compounds, norwogonin was the most potent against multidrug-resistant A. baumannii strains. Further studies are warranted to ascertain the prophylactic and therapeutic potential of norwogonin for infections due to multidrug-resistant A. baumannii.
-
Paisio, Cintia E; Quevedo, María R; Talano, Melina A; González, Paola S; Agostini, Elizabeth
2014-08-01
The use of native bacteria is a useful strategy to decontaminate industrial effluents. In this work, two bacterial strains isolated from polluted environments constitutes a promising alternative since they were able to remove several phenolic compounds not only from synthetic solutions but also from effluents derived from a chemical industry and a tannery which are complex matrices. Acinetobacter sp. RTE 1.4 showed ability to completely remove 2-methoxyphenol (1000 mg/L) while Rhodococcus sp. CS 1 not only degrade the same concentration of this compound but also removed 4- chlorophenol, 2,4-dichlorophenol and pentachlorophenol with high efficiency. Moreover, both bacteria degraded phenols naturally present or even exogenously added at high concentrations in effluents from the chemical industry and a tannery in short time (up to 5 d). In addition, a significant reduction of biological oxygen demand and chemical oxygen demand values was achieved after 7 d of treatment for both effluents using Acinetobacter sp. RTE 1.4 and Rhodococcus sp. CS1, respectively. These results showed that Acinetobacter sp. RTE1.4 and Rhodococcus sp. CS 1 might be considered as useful biotechnological tools for an efficient treatment of different effluents, since they showed wide versatility to detoxify these complex matrices, even supplemented with high phenol concentrations.
-
Deris, Zakuan Zainy; Shafei, Mohd Nazri; Harun, Azian
2011-01-01
Objective To determine the risk factors and outcomes of imipenem-resistant Acinetobacter baumannii (IRAB) bloodstream infection (BSI) cases, since there is very little publication on Acinetobacter baumannii infections from Malaysia. Methods A cross sectional study of 41 cases (73.2%) of imipenem-sensitive Acinetobacter baumanii (ISAB) and 15 cases (26.8%) of IRAB was conducted in a teaching hospital which was located at North-Eastern state of Malaysia. Results There was no independent risk factor for IRAB BSI identified but IRAB BSI was significantly associated with longer bacteraemic days [OR 1.23 (95% CI 1.01, 1.50)]. Although prior use of carbepenems and cephalosporin were higher among IRAB than ISAB group, statistically they were not significant. There was no significant difference in term of outcomes between the two groups. Conclusions Although statistically not significant, this analysis compliments previous publication highlighting the importance of appropriate empiric antibiotic usage in hospital especially carbepenems and need further evaluation with bigger subjects. PMID:23569782
-
Functional Features of TonB Energy Transduction Systems of Acinetobacter baumannii
Zimbler, Daniel L.; Arivett, Brock A.; Beckett, Amber C.; Menke, Sharon M.
2013-01-01
Acinetobacter baumannii is an opportunistic pathogen that causes severe nosocomial infections. Strain ATCC 19606T utilizes the siderophore acinetobactin to acquire iron under iron-limiting conditions encountered in the host. Accordingly, the genome of this strain has three tonB genes encoding proteins for energy transduction functions needed for the active transport of nutrients, including iron, through the outer membrane. Phylogenetic analysis indicates that these tonB genes, which are present in the genomes of all sequenced A. baumannii strains, were acquired from different sources. Two of these genes occur as components of tonB-exbB-exbD operons and one as a monocistronic copy; all are actively transcribed in ATCC 19606T. The abilities of components of these TonB systems to complement the growth defect of Escherichia coli W3110 mutants KP1344 (tonB) and RA1051 (exbBD) under iron-chelated conditions further support the roles of these TonB systems in iron acquisition. Mutagenesis analysis of ATCC 19606T tonB1 (subscripted numbers represent different copies of genes or proteins) and tonB2 supports this hypothesis: their inactivation results in growth defects in iron-chelated media, without affecting acinetobactin biosynthesis or the production of the acinetobactin outer membrane receptor protein BauA. In vivo assays using Galleria mellonella show that each TonB protein is involved in, but not essential for, bacterial virulence in this infection model. Furthermore, we observed that TonB2 plays a role in the ability of bacteria to bind to fibronectin and to adhere to A549 cells by uncharacterized mechanisms. Taken together, these results indicate that A. baumannii ATCC 19606T produces three independent TonB proteins, which appear to provide the energy-transducing functions needed for iron acquisition and cellular processes that play a role in the virulence of this pathogen. PMID:23817614
-
Kim, Dae Hun; Ko, Kwan Soo
2015-07-01
To investigate pmrCAB sequence divergence in 5 species of Acinetobacter baumannii complex, a total of 80 isolates from a Korean hospital were explored. We evaluated nucleotide and amino acid polymorphisms of pmrCAB operon, and phylogenetic trees were constructed for each gene of prmCAB operon. Colistin and polymyxin B susceptibility was determined for all isolates, and multilocus sequence typing was also performed for A. baumannii isolates. Our results showed that each species of A. baumannii complex has divergent pmrCAB operon sequences. We identified a distinct pmrCAB allele allied with Acinetobacter nosocomialis in gene trees. Different grouping in each gene tree suggests sporadic recombination or emergence of pmrCAB genes among Acinetobacter species. Sequence polymorphisms among Acinetobacter species might not be associated with colistin resistance. We revealed that a distinct pmrCAB allele may be widespread across the continents such as North America and Asia and that sporadic genetic recombination or emergence of pmrCAB genes might occur. Copyright © 2015 Elsevier Inc. All rights reserved.
-
Brahmi, Soumia; Touati, Abdelaziz; Cadière, Axelle; Djahmi, Nassima; Pantel, Alix; Sotto, Albert; Dunyach-Remy, Catherine
2016-01-01
To determine the occurrence of carbapenem-resistant Acinetobacter baumannii in fish fished from the Mediterranean Sea near the Bejaia coast (Algeria), we studied 300 gills and gut samples that had been randomly and prospectively collected during 1 year. After screening on selective agar media, using PCR arrays and whole-genome sequencing, we identified for the first time two OXA-23-producing A. baumannii strains belonging to the widespread sequence type 2 (ST2)/international clone II and harboring aminoglycoside-modifying enzymes [aac(6′)-Ib and aac(3′)-I genes]. PMID:26787693
-
Regulation of the aceI multidrug efflux pump gene in Acinetobacter baumannii.
Liu, Qi; Hassan, Karl A; Ashwood, Heather E; Gamage, Hasinika K A H; Li, Liping; Mabbutt, Bridget C; Paulsen, Ian T
2018-06-01
To investigate the function of AceR, a putative transcriptional regulator of the chlorhexidine efflux pump gene aceI in Acinetobacter baumannii. Chlorhexidine susceptibility and chlorhexidine induction of aceI gene expression were determined by MIC and quantitative real-time PCR, respectively, in A. baumannii WT and ΔaceR mutant strains. Recombinant AceR was prepared as both a full-length protein and as a truncated protein, AceR (86-299), i.e. AceRt, which has the DNA-binding domain deleted. The binding interaction of the purified AceR protein and its putative operator region was investigated by electrophoretic mobility shift assays and DNase I footprinting assays. The binding of AceRt with its putative ligand chlorhexidine was examined using surface plasmon resonance and tryptophan fluorescence quenching assays. MIC determination assays indicated that the ΔaceI and ΔaceR mutant strains both showed lower resistance to chlorhexidine than the parental strain. Chlorhexidine-induced expression of aceI was abolished in a ΔaceR background. Electrophoretic mobility shift assays and DNase I footprinting assays demonstrated chlorhexidine-stimulated binding of AceR with two sites upstream of the putative aceI promoter. Surface plasmon resonance and tryptophan fluorescence quenching assays suggested that the purified ligand-binding domain of the AceR protein was able to bind with chlorhexidine with high affinity. This study provides strong evidence that AceR is an activator of aceI gene expression when challenged with chlorhexidine. This study is the first characterization, to our knowledge, of a regulator controlling expression of a PACE family multidrug efflux pump.
-
Identification of Lama glama as Reservoirs for Acinetobacter lwoffii
Ledesma, Martín M.; Díaz, Ailén M.; Barberis, Claudia; Vay, Carlos; Manghi, Marcela A.; Leoni, Juliana; Castro, Marisa S.; Ferrari, Alejandro
2017-01-01
South American Camelids have an increasing relevance in local economies, worldwide. These animals are bred for their meat, fur and as companion and therapy animals. Thus, their sanitary status should be well-established. According to the OIE (World Organization for Animal Health), respiratory infections mainly produced by Pasteurella spp. have been reported for camelids. It has been stated that this microorganism causes a mild disease, although many authors report it is an important cause of mortality among alpacas. Nevertheless, the incidence of infection by Pasteurella spp. in camelids still needs to be investigated. The aim of the present study was to analyze the occurrence of nasopharyngeal colonization of Lama glama by respiratory bacteria, and to assess the usefulness of serological tests for clinical diagnosis. The colonization was studied by culture techniques carried out with material taken by nasopharyngeal swabs. Bacterial isolates were first phenotypically characterized and then identified by MALDI/TOF-MS. The presence of specific serum antibodies was studied by ELISA and Western blot. In the present work Pasteurella spp. was not found. Nevertheless, we report for the first time, the colonization of L. glama by bacteria of the Acinetobacter lwoffii, at a reliable level in 19.4% of the animals. Acinetobacter species are found in different environmental sources, as well as vegetables, animals, and humans, and their role in infections has recently gained relevance. The results presented herein contribute to a better understanding of the respiratory microbiota in camelids, and increase the knowledge about environmental distribution of Acinetobacter non-baumanii species. Given that these respiratory bacteria might be the cause of infection among cattle, and even humans, this report highlights the need for further research. PMID:28303121
-
Nhu, Nguyen Thi Khanh; Lan, Nguyen Phu Huong; Campbell, James I.; Parry, Christopher M.; Thompson, Corinne; Tuyen, Ha Thanh; Hoang, Nguyen Van Minh; Tam, Pham Thi Thanh; Le, Vien Minh; Nga, Tran Vu Thieu; Nhu, Tran Do Hoang; Van Minh, Pham; Nga, Nguyen Thi Thu; Thuy, Cao Thu; Dung, Le Thi; Yen, Nguyen Thi Thu; Van Hao, Nguyen; Loan, Huynh Thi; Yen, Lam Minh; Nghia, Ho Dang Trung; Hien, Tran Tinh; Thwaites, Louise; Thwaites, Guy; Chau, Nguyen Van Vinh
2014-01-01
Ventilator-associated pneumonia (VAP) is a serious healthcare-associated infection that affects up to 30 % of intubated and mechanically ventilated patients in intensive care units (ICUs) worldwide. The bacterial aetiology and corresponding antimicrobial susceptibility of VAP is highly variable, and can differ between countries, national provinces and even between different wards in the same hospital. We aimed to understand and document changes in the causative agents of VAP and their antimicrobial susceptibility profiles retrospectively over an 11 year period in a major infectious disease hospital in southern Vietnam. Our analysis outlined a significant shift from Pseudomonas aeruginosa to Acinetobacter spp. as the most prevalent bacteria isolated from quantitative tracheal aspirates in patients with VAP in this setting. Antimicrobial resistance was common across all bacterial species and we found a marked proportional annual increase in carbapenem-resistant Acinetobacter spp. over a 3 year period from 2008 (annual trend; odds ratio 1.656, P = 0.010). We further investigated the possible emergence of a carbapenem-resistant Acinetobacter baumannii clone by multiple-locus variable number tandem repeat analysis, finding a blaOXA-23-positive strain that was associated with an upsurge in the isolation of this pathogen. We additionally identified a single blaNDM-1-positive A. baumannii isolate. This work highlights the emergence of a carbapenem-resistant clone of A. baumannii and a worrying trend of antimicrobial resistance in the ICU of the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam. PMID:25038137
-
Seuylemezian, Arman; Vaishampayan, Parag; Cooper, Kerry
2018-01-01
ABSTRACT We report here the draft genome sequences of four strains isolated from spacecraft-associated surfaces exhibiting increased resistance to stressors such as UV radiation and exposure to H2O2. The draft genomes of strains 1P01SCT, FO-92T, 50v1, and 2P01AA had sizes of 5,500,894 bp, 4,699,376 bp, 3,174,402 bp, and 4,328,804 bp, respectively. PMID:29439046
-
Hammoudi, D; Moubareck, C Ayoub; Hakime, N; Houmani, M; Barakat, A; Najjar, Z; Suleiman, M; Fayad, N; Sarraf, R; Sarkis, D Karam
2015-07-01
The acquisition of carbapenemases by Acinetobacter baumannii is reported increasingly worldwide, but data from Lebanon are limited. The aims of this study were to evaluate the prevalence of imipenem-resistant A. baumannii in Lebanon, identify resistance determinants, and detect clonal relatedness. Imipenem-resistant A. baumannii were collected from nine Lebanese hospitals during 2012. Antimicrobial susceptibility, the cloxacillin effect, and ethylenediaminetetraacetic acid (EDTA) synergy were determined. Genes encoding carbapenemases and insertion sequence ISAba1 were screened via PCR sequencing. ISAba1 position relative to genes encoding Acinetobacter-derived cephalosporinases (ADCs) and OXA-23 was studied by PCR mapping. Clonal linkage was examined by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). Out of 724 A. baumannii isolated in 2012, 638 (88%) were imipenem-resistant. Of these, 142 were analyzed. Clavulanic acid-imipenem synergy suggested carbapenem-hydrolyzing extended-spectrum β-lactamase. A positive cloxacillin test indicated ADCs, while EDTA detection strips were negative. Genotyping indicated that 90% of isolates co-harbored blaOXA-23 and blaGES-11. The remaining strains had blaOXA-23, blaOXA-24, blaGES-11, or blaOXA-24 with blaGES-11. ISAba1 was located upstream of blaADC and blaOXA-23 in 97% and 100% of isolates, respectively. ERIC-PCR fingerprinting revealed 18 pulsotypes spread via horizontal gene transfer and clonal dissemination. This survey established baseline evidence of OXA-23 and GES-11-producing A. baumannii in Lebanon, indicating the need for further surveillance. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.
-
Saranathan, Rajagopalan; Pagal, Sudhakar; Sawant, Ajit R; Tomar, Archana; Madhangi, M; Sah, Suresh; Satti, Annapurna; Arunkumar, K P; Prashanth, K
2017-10-03
Acinetobacter baumannii is an important human pathogen and considered as a major threat due to its extreme drug resistance. In this study, the genome of a hyper-virulent MDR strain PKAB07 of A. baumannii isolated from an Indian patient was sequenced and analyzed to understand its mechanisms of virulence, resistance and evolution. Comparative genome analysis of PKAB07 revealed virulence and resistance related genes scattered throughout the genome, instead of being organized as an island, indicating the highly mosaic nature of the genome. Many intermittent horizontal gene transfer events, insertion sequence (IS) element insertions identified were augmenting resistance machinery and elevating the SNP densities in A. baumannii eventually aiding in their swift evolution. ISAba1, the most widely distributed insertion sequence in A. baumannii was found in multiple sites in PKAB07. Out of many ISAba1 insertions, we identified novel insertions in 9 different genes wherein insertional inactivation of adeN (tetR type regulator) was significant. To assess the significance of this disruption in A. baumannii, adeN mutant and complement strains were constructed in A. baumannii ATCC 17978 strain and studied. Biofilm levels were abrogated in the adeN knockout when compared with the wild type and complemented strain of adeN knockout. Virulence of the adeN knockout mutant strain was observed to be high, which was validated by in vitro experiments and Galleria mellonella infection model. The overexpression of adeJ, a major component of AdeIJK efflux pump observed in adeN knockout strain could be the possible reason for the elevated virulence in adeN mutant and PKB07 strain. Knocking out of adeN in ATCC strain led to increased resistance and virulence at par with the PKAB07. Disruption of tetR type regulator adeN by ISAba1 consequently has led to elevated virulence in this pathogen.
-
Li, Philip Hei; Cheng, Vincent C C; Yip, Terence; Yap, Desmond Y H; Lui, Sing-Leung; Lo, Wai-Kei
2017-01-01
♦ BACKGROUND: Acinetobacter spp. is an important cause of peritoneal dialysis (PD)-related peritonitis, but studies on Acinetobacter peritonitis have been scarce. In view of the rising concern of carbapenem-resistant Acinetobacter (CRA) and multidrug-resistant Acinetobacter (MDRA) infections, we conducted this study on the incidence of Acinetobacter peritonitis and the impact of CRA and MDRA on its outcome. ♦ METHODS: We retrospectively evaluated the clinical characteristics, prevalence, antibiotic sensitivity patterns, outcomes, and factors associated with treatment failure over the past 16 years in our patients with Acinetobacter PD-related peritonitis. ♦ RESULTS: Out of 2,389 episodes of peritonitis, there were 66 episodes (3%) of Acinetobacter peritonitis occurring in 59 patients. Twelve episodes were caused by MDRA (18%), of which 5 were CRA (8%). There was a progressive increase in the incidence of MDRA and CRA infections over the study period. Most isolates were sensitive to sulbactam combinations (ampicillin-sulbactam [95.4%] and cefoperazone-sulbactam [93.9%]), aminoglycosides (amikacin [92.4%], tobramycin [90.9%], and gentamicin [89.4%]), and carbapenems (imipenem [92.2%]). There was 1 case of relapse. Fifteen episodes resulted in catheter removal (23%), and 7 patients died (11%). Hypoalbuminemia (odds ratio [OR] = 0.85, p = 0.006) and carbapenem resistance (OR = 18.2, p = 0.049) were significantly associated with higher rates of treatment failure. ♦ CONCLUSION: Both carbapenem resistance and hypoalbuminemia were significantly associated with treatment failure. Up to 80% of peritonitis episodes by CRA resulted in catheter loss or mortality. Sulbactam combinations and/or aminoglycosides remained effective for the majority of Acinetobacter isolates. There seemed to be an increasing relative incidence of MDRA and CRA infections over the past 16 years. Copyright © 2017 International Society for Peritoneal Dialysis.
-
Drag reduction by Acinetobacter calcoaceticus BD4.
Sar, N; Rosenberg, E
1987-09-01
The encapsulated bacterium Acinetobacter calcoaceticus BD4 at a density of 3.6 X 10(9) cells per ml reduced the friction of turbulent water in a narrow pipe by 55%. This drag reduction was due to the tightly bound polysaccharide capsules (0.4 mg per ml) of culture. Capsule-deficient mutants of BD4 failed to reduce drag. The cell-bound polysaccharide demonstrated a threefold-higher drag-reducing activity than the polymer which was free in solution.
-
Hujer, Kristine M; Hamza, Nashaat S; Hujer, Andrea M; Perez, Federico; Helfand, Marion S; Bethel, Christopher R; Thomson, Jodi M; Anderson, Vernon E; Barlow, Miriam; Rice, Louis B; Tenover, Fred C; Bonomo, Robert A
2005-07-01
Acinetobacter spp. are emerging as opportunistic hospital pathogens that demonstrate resistance to many classes of antibiotics. In a metropolitan hospital in Cleveland, a clinical isolate of Acinetobacter baumannii that tested resistant to cefepime and ceftazidime (MIC = 32 microg/ml) was identified. Herein, we sought to determine the molecular basis for the extended-spectrum-cephalosporin resistance. Using analytical isoelectric focusing, a beta-lactamase with a pI of > or = 9.2 was detected. PCR amplification with specific A. baumannii cephalosporinase primers yielded a 1,152-bp product which, when sequenced, identified a novel 383-amino-acid class C enzyme. Expressed in Escherichia coli DH10B, this beta-lactamase demonstrated greater resistance against ceftazidime and cefotaxime than cefepime (4.0 microg/ml versus 0.06 microg/ml). The kinetic characteristics of this beta-lactamase were similar to other cephalosporinases found in Acinetobacter spp. In addition, this cephalosporinase was inhibited by meropenem, imipenem, ertapenem, and sulopenem (K(i) < 40 microM). The amino acid compositions of this novel enzyme and other class C beta-lactamases thus far described for A. baumannii, Acinetobacter genomic species 3, and Oligella urethralis in Europe and South Africa suggest that this cephalosporinase defines a unique family of class C enzymes. We propose a uniform designation for this family of cephalosporinases (Acinetobacter-derived cephalosporinases [ADC]) found in Acinetobacter spp. and identify this enzyme as ADC-7 beta-lactamase. The coalescence of Acinetobacter ampC beta-lactamases into a single common ancestor and the substantial phylogenetic distance separating them from other ampC genes support the logical value of developing a system of nomenclature for these Acinetobacter cephalosporinase genes.
-
Hujer, Kristine M.; Hamza, Nashaat S.; Hujer, Andrea M.; Perez, Federico; Helfand, Marion S.; Bethel, Christopher R.; Thomson, Jodi M.; Anderson, Vernon E.; Barlow, Miriam; Rice, Louis B.; Tenover, Fred C.; Bonomo, Robert A.
2005-01-01
Acinetobacter spp. are emerging as opportunistic hospital pathogens that demonstrate resistance to many classes of antibiotics. In a metropolitan hospital in Cleveland, a clinical isolate of Acinetobacter baumannii that tested resistant to cefepime and ceftazidime (MIC = 32 μg/ml) was identified. Herein, we sought to determine the molecular basis for the extended-spectrum-cephalosporin resistance. Using analytical isoelectric focusing, a β-lactamase with a pI of ≥9.2 was detected. PCR amplification with specific A. baumannii cephalosporinase primers yielded a 1,152-bp product which, when sequenced, identified a novel 383-amino-acid class C enzyme. Expressed in Escherichia coli DH10B, this β-lactamase demonstrated greater resistance against ceftazidime and cefotaxime than cefepime (4.0 μg/ml versus 0.06 μg/ml). The kinetic characteristics of this β-lactamase were similar to other cephalosporinases found in Acinetobacter spp. In addition, this cephalosporinase was inhibited by meropenem, imipenem, ertapenem, and sulopenem (Ki < 40 μM). The amino acid compositions of this novel enzyme and other class C β-lactamases thus far described for A. baumannii, Acinetobacter genomic species 3, and Oligella urethralis in Europe and South Africa suggest that this cephalosporinase defines a unique family of class C enzymes. We propose a uniform designation for this family of cephalosporinases (Acinetobacter-derived cephalosporinases [ADC]) found in Acinetobacter spp. and identify this enzyme as ADC-7 β-lactamase. The coalescence of Acinetobacter ampC β-lactamases into a single common ancestor and the substantial phylogenetic distance separating them from other ampC genes support the logical value of developing a system of nomenclature for these Acinetobacter cephalosporinase genes. PMID:15980372
-
Touchon, Marie; Brisse, Sylvain; Rocha, Eduardo P.C.
2017-01-01
Summary Most bacteria have poorly characterized environmental reservoirs and unknown closely related species. This hampers the study of bacterial evolutionary ecology because both the environment and the genetic background of ancestral lineages are unknown. We combined metagenomics, comparative genomics and phylogenomics to overcome this limitation, to identify novel taxa and to propose environments where they can be isolated. We applied this method to characterize the ecological distribution of known and novel lineages of Acinetobacter spp. We observed two major environmental transitions at deep phylogenetic levels, splitting the genus into three ecologically differentiated clades. One of these has rapidly shifted towards host‐association by acquiring genes involved in bacteria‐eukaryote interactions. We show that environmental perturbations affect species distribution in predictable ways: bovines have very diverse communities of Acinetobacter, unless they were administered antibiotics, in which case they show highly uniform communities of Acinetobacter spp. that resemble those of humans. Our results uncover the diversity of bacterial lineages, overpassing the limitations of classical cultivation methods and highlight the role of the environment in shaping their evolution. PMID:28967182
-
Cerezales, Mónica; Ocampo-Sosa, Alain A; Álvarez Montes, Laura; Díaz Ríos, Catalina; Bustamante, Zulema; Santos, Jazmín; Martínez-Martínez, Luis; Higgins, Paul G; Gallego, Lucía
2018-02-22
Acinetobacter baumannii causes serious hospital-acquired infections and has been positioned as a priority organism by the World Health Organization. This study includes 36 A. baumannii isolates from a children hospital recovered between March 2014 and May 2015 in Cochabamba. The majority of the isolates were recovered from blood cultures (n=10, 31.3%) and respiratory samples (n=11, 34.4%); fifty three percent of the patients were younger than one month old. Most of these isolates (n=30, 80.6%) were extremely-drug resistant (XDR) and 8.3% were multidrug-resistant (MDR). The circulation of two predominant clones including 25 isolates was determined by PFGE; 9 of the isolates were considered sporadic strains. The isolates grouped in the predominant clones and five of the unrelated sporadic strains were SLV or DLV of CC110, belonging to IC7; the rest of the isolates were SLV or DLV of another CC. All the carbapenem-resistant isolates (88.9%) carried the blaOXA-23-like in a similar structure to Tn2008 located on the chromosome and the aac(3)-IIa gene was present in all the aminoglycoside-resistant isolates (86.1%). Strong biofilm producers were found among these isolates, being the strongest ones those recovered from the hospital environment, catheter, blood and LCR, all of them belonged to the unrelated sporadic strains. The present study demonstrated the predominance and spread of closely related XDR A. baumannii isolates, what confers increasing risk to children and is of major concern due to the kind of infections and the lack of therapeutic alternatives to treat them.
-
Lee, Kyungwon; Yong, Dongeun; Yum, Jong Hwa; Lim, Yong Sik; Bolmström, Anne; Qwärnström, Anette; Karlsson, Åsa; Chong, Yunsop
2005-01-01
The Etest MBL (AB BIODISK, Solna, Sweden) correctly differentiated all 57 isolates of Acinetobacter spp. and Pseudomonas aeruginosa with the blaIMP-1 allele and 135 of 137 (98.5%) Acinetobacter spp. and Pseudomonas spp. isolates with the blaVIM-2 allele. The Etest MBL was reliable for detecting the IMP-1- and VIM-2-producing Pseudomonas and Acinetobacter isolates. PMID:15695713
-
Identification and Characterization of an Acinetobacter baumannii Biofilm-Associated Protein▿
Loehfelm, Thomas W.; Luke, Nicole R.; Campagnari, Anthony A.
2008-01-01
We have identified a homologue to the staphylococcal biofilm-associated protein (Bap) in a bloodstream isolate of Acinetobacter baumannii. The fully sequenced open reading frame is 25,863 bp and encodes a protein with a predicted molecular mass of 854 kDa. Analysis of the nucleotide sequence reveals a repetitive structure consistent with bacterial cell surface adhesins. Bap-specific monoclonal antibody (MAb) 6E3 was generated to an epitope conserved among 41% of A. baumannii strains isolated during a recent outbreak in the U.S. military health care system. Flow cytometry confirms that the MAb 6E3 epitope is surface exposed. Random transposon mutagenesis was used to generate A. baumannii bap1302::EZ-Tn5, a mutant negative for surface reactivity to MAb 6E3 in which the transposon disrupts the coding sequence of bap. Time course confocal laser scanning microscopy and three-dimensional image analysis of actively growing biofilms demonstrates that this mutant is unable to sustain biofilm thickness and volume, suggesting a role for Bap in supporting the development of the mature biofilm structure. This is the first identification of a specific cell surface protein directly involved in biofilm formation by A. baumannii and suggests that Bap is involved in intercellular adhesion within the mature biofilm. PMID:18024522
-
Rumbo, C.; Gato, E.; López, M.; Ruiz de Alegría, C.; Fernández-Cuenca, F.; Martínez-Martínez, L.; Vila, J.; Pachón, J.; Cisneros, J. M.; Rodríguez-Baño, J.; Pascual, A.
2013-01-01
We investigated the mechanisms of resistance to carbapenems, aminoglycosides, glycylcyclines, tetracyclines, and quinolones in 90 multiresistant clinical strains of Acinetobacter baumannii isolated from two genetically unrelated A. baumannii clones: clone PFGE-ROC-1 (53 strains producing the OXA-58 β-lactamase enzyme and 18 strains with the OXA-24 β-lactamase) and clone PFGE-HUI-1 (19 strains susceptible to carbapenems). We used real-time reverse transcriptase PCR to correlate antimicrobial resistance (MICs) with expression of genes encoding chromosomal β-lactamases (AmpC and OXA-51), porins (OmpA, CarO, Omp33, Dcap-like, OprB, Omp25, OprC, OprD, and OmpW), and proteins integral to six efflux systems (AdeABC, AdeIJK, AdeFGH, CraA, AbeM, and AmvA). Overexpression of the AdeABC system (level of expression relative to that by A. baumannii ATCC 17978, 30- to 45-fold) was significantly associated with resistance to tigecycline, minocycline, and gentamicin and other biological functions. However, hyperexpression of the AdeIJK efflux pump (level of expression relative to that by A. baumannii ATCC 17978, 8- to 10-fold) was significantly associated only with resistance to tigecycline and minocycline (to which the TetB efflux system also contributed). TetB and TetA(39) efflux pumps were detected in clinical strains and were associated with resistance to tetracyclines and doxycycline. The absence of the AdeABC system and the lack of expression of other mechanisms suggest that tigecycline-resistant strains of the PFGE-HUI-1 clone may be associated with a novel resistance-nodulation-cell efflux pump (decreased MICs in the presence of the inhibitor Phe-Arg β-naphthylamide dihydrochloride) and the TetA(39) system. PMID:23939894
-
Acinetobacter Species Infections Among Navy and Marine Corps Beneficiaries: 2013 Annual Report
2014-11-19
cases in 2013, DON providers most commonly prescribed colistin, minocycline , piperacillin/tazobactam, and trimethoprim/sulfamethoxazole. DOD...administration route, the following antibiotics were all equally common in the DON for resistant Acinetobacter cases: colistin, minocycline , piperacillin
-
Lehtinen, Tapio; Efimova, Elena; Tremblay, Pier-Luc; Santala, Suvi; Zhang, Tian; Santala, Ville
2017-11-01
Microbial electrosynthesis (MES) is a promising technology for the reduction of carbon dioxide into value-added multicarbon molecules. In order to broaden the product profile of MES processes, we developed a two-stage process for microbial conversion of carbon dioxide and electricity into long chain alkyl esters. In the first stage, the carbon dioxide is reduced to organic compounds, mainly acetate, in a MES process by Sporomusa ovata. In the second stage, the liquid end-products of the MES process are converted to the final product by a second microorganism, Acinetobacter baylyi in an aerobic bioprocess. In this proof-of-principle study, we demonstrate for the first time the bacterial production of long alkyl esters (wax esters) from carbon dioxide and electricity as the sole sources of carbon and energy. The process holds potential for the efficient production of carbon-neutral chemicals or biofuels. Copyright © 2017 Elsevier Ltd. All rights reserved.
-
An Ribonuclease T2 Family Protein Modulates Acinetobacter baumannii Abiotic Surface Colonization
Jacobs, Anna C.; Blanchard, Catlyn E.; Catherman, Seana C.; Dunman, Paul M.; Murata, Yoshihiko
2014-01-01
Acinetobacter baumannii is an emerging bacterial pathogen of considerable medical concern. The organism's transmission and ability to cause disease has been associated with its propensity to colonize and form biofilms on abiotic surfaces in health care settings. To better understand the genetic determinants that affect biomaterial attachment, we performed a transposon mutagenesis analysis of abiotic surface-colonization using A. baumannii strain 98-37-09. Disruption of an RNase T2 family gene was found to limit the organism's ability to colonize polystyrene, polypropylene, glass, and stainless steel surfaces. DNA microarray analyses revealed that in comparison to wild type and complemented cells, the RNase T2 family mutant exhibited reduced expression of 29 genes, 15 of which are predicted to be associated with bacterial attachment and surface-associated motility. Motility assays confirmed that RNase T2 mutant displays a severe motility defect. Taken together, our results indicate that the RNase T2 family protein identified in this study is a positive regulator of A. baumannii's ability to colonize inanimate surfaces and motility. Moreover, the enzyme may be an effective target for the intervention of biomaterial colonization, and consequently limit the organism's transmission within the hospital setting. PMID:24489668
-
Touati, Arabella; Achour, Wafa; Cherif, Ahmed; Hmida, Hayet Ben; Afif, Firas Bou; Jabnoun, Sami; Khrouf, Naima; Hassen, Assia Ben
2009-06-01
We describe an outbreak of nosocomial respiratory infection caused by multi-drug resistant Acinetobacter baumannii in a neonatal intensive care unit (NICU) in Tunis and our investigation to determine the source. Between May 2006 and February 2007, 31 infants hospitalized in the NICU of the Centre of Maternity and Neonatology of La Rabta in Tunis developed A. baumannii pneumonia. A case (infected infant) was defined as any patient hospitalized in the NICU during the outbreak period, with clinical signs of pneumonia and isolation of A. baumannii from tracheal aspirate. Ten rectal swabs and 98 environmental specimens were collected for the epidemiological investigation. Thirty-nine A. baumannii isolates were collected: 31 clinical strains from tracheal aspirates (>10(3) colony-forming units [CFU]/mL), 3 environmental strains from incubators, and 5 from rectal swab. For the genotyping method, we used pulsed-field gel electrophoresis using ApaI restriction endonuclease. Thirty-one neonates developed multiple drug-resistant A. baumannii-associated pneumonia with 10 deaths due to A. baumannii infection, 48.4% had very low birth weight (
-
Fiester, Steven E.; Schmidt, Robert E.; Beckett, Amber C.; Ticak, Tomislav; Carrier, Mary V.; Ghosh, Rajarshi; Ohneck, Emily J.; Metz, Maeva L.; Sellin Jeffries, Marlo K.; Actis, Luis A.
2016-01-01
Acinetobacter baumannii is an opportunistic Gram-negative pathogen that causes a wide range of infections including pneumonia, septicemia, necrotizing fasciitis and severe wound and urinary tract infections. Analysis of A. baumannii representative strains grown in Chelex 100-treated medium for hemolytic activity demonstrated that this pathogen is increasingly hemolytic to sheep, human and horse erythrocytes, which interestingly contain increasing amounts of phosphatidylcholine in their membranes. Bioinformatic, genetic and functional analyses of 19 A. baumannii isolates showed that the genomes of each strain contained two phosphatidylcholine-specific phospholipase C (PC-PLC) genes, which were named plc1 and plc2. Accordingly, all of these strains were significantly hemolytic to horse erythrocytes and their culture supernatants tested positive for PC-PLC activity. Further analyses showed that the transcriptional expression of plc1 and plc2 and the production of phospholipase and thus hemolytic activity increased when bacteria were cultured under iron-chelation as compared to iron-rich conditions. Testing of the A. baumannii ATCC 19606T plc1::aph-FRT and plc2::aph isogenic insertion derivatives showed that these mutants had a significantly reduced PC-PLC activity as compared to the parental strain, while testing of plc1::ermAM/plc2::aph demonstrated that this double PC-PLC isogenic mutant expressed significantly reduced cytolytic and hemolytic activity. Interestingly, only plc1 was shown to contribute significantly to A. baumannii virulence using the Galleria mellonella infection model. Taken together, our data demonstrate that both PLC1 and PLC2, which have diverged from a common ancestor, play a concerted role in hemolytic and cytolytic activities; although PLC1 seems to play a more critical role in the virulence of A. baumannii when tested in an invertebrate model. These activities would provide access to intracellular iron stores this pathogen could use during
-
Soon, Rachel L; Nation, Roger L; Harper, Marina; Adler, Ben; Boyce, John D; Tan, Chun-Hong; Li, Jian; Larson, Ian
2011-12-01
The diminishing antimicrobial development pipeline has forced the revival of colistin as a last line of defence against infections caused by multidrug-resistant Gram-negative 'superbugs' such as Acinetobacter baumannii. The complete loss of lipopolysaccharide (LPS) mediates colistin resistance in some A. baumannii strains. Atomic force microscopy was used to examine the surface properties of colistin-susceptible and -resistant A. baumannii strains at mid-logarithmic and stationary growth phases in liquid and in response to colistin treatment. The contribution of LPS to surface properties was investigated using A. baumannii strains constructed with and without the lpxA gene. Bacterial spring constant measurements revealed that colistin-susceptible cells were significantly stiffer than colistin-resistant cells at both growth phases (P<0.01), whilst colistin treatment at high concentrations (32 mg/L) resulted in more rigid surfaces for both phenotypes. Multiple, large adhesive peaks frequently noted in force curves captured on colistin-susceptible cells were not evident for colistin-resistant cells. Adhesion events were markedly reduced following colistin exposure. The cell membranes of strains of both phenotypes remained intact following colistin treatment, although fine topographical details were illustrated. These studies, conducted for the first time on live A. baumannii cells in liquid, have contributed to our understanding of the action of colistin in this problematic pathogen. Copyright © 2011 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.
-
Cartelle Gestal, Monica; Zurita, Jeannete; Gualpa, Gabriela; Gonzalez, Cecibel; Paz Y Mino, Ariane
2016-12-30
Acinetobacter baumannii (ABA) is an important opportunistic pathogen associated with high mortality rates in intensive care units (ICUs). An outbreak in the ICU of a secondary-level hospital in Quito, Ecuador, occurred during April and May 2015 and was successfully controlled. Enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) and repetitive element palindromic (REP)-PCR was conducted on all isolates recovered from patients, as well as environmental samples, to confirm the presence of an outbreak. A case-control study was conducted by comparing the clinical histories of the affected patients and of control patients present in the ICU during the outbreak period who did not present a positive culture for ABA. Five patients were infected and two were colonized with the same clonal strain of ABA, which was also identified on the stethoscope and a monitor associated with an isolation room. Statistical analysis of case histories did not identify any additional risk factors, but the outbreak was initiated by one patient in the isolation room of the ICU who was infected with the outbreak strain. All patients who ocupied that room after the index case tested positive for at least one culture of ABA. The outbreak strain was found on the stethoscope, and a subclone was found on the monitor of that room. Having access to basic equipment will enable well-trained professionals to rapidly detect and initiate the control process of an outbreak, saving lives and money spent on nosocomial infection treatments.
-
Mana, Nassima; Louni, Meriem; Parola, Philippe; Bitam, Idir
2017-08-01
There are two majorspecies of medically important lice that parasitize humans: Phthirus pubis, found in pubic hair, and Pediculus humanus. Pediculus humanus consists of two eco types that live in specific niches on the human host: body lice (Pediculus humanus humanus), found on the human body and clothing, and head lice (Pediculus humanus capitis), found on the scalp. To date, only body lice are known to be vectors of human disease; however, it has recently been reported that the DNA of several bacterial agents has been detected in head lice, raising questions about their role in the transmission of pathogens. This issue caught our attention, in addition to the fact that the pathogenic bacteria associated with P. pubis and P. humanus capitis have never been investigated in Algeria. To investigate this,molecular techniques (real-time PCR) were used to screen for the presence of Acinetobacter spp., Bartonella spp., Borrelia spp. and Rickettsia prowazekii DNA from P. humanus capitis (64 lice) collected from schoolchildren,and P. pubis (4 lice),collected from one adultman living in Algiers. Positive samples for Acinetobacter spp.were identified by sequencing therpoBgene. Conventional PCR targeting the partial Cytb gene was used to determine the phylogenetic clade of the collected lice. Of the 64 samples collected, Acinetobacter spp. DNA was detected in 17/64 (27%) of head lice, identified as: A. baumannii (14%), A. johnsonii (11%) and A. variabilis (2%). Of the four P. pubissamples, 2(50%) were positive for A. johnsonii. The phylogenetic tree based on the Cytb gene revealed that P. humanus capitis were grouped into clades A and B. In this study, we report andidentify for the first time Acinetobacter spp.in Algerian P. pubis and P. humanus capitis. The detection of the genus Acinetobacter in lice should not be underestimated, especially in P. humanus capitis, which is distributed worldwide. However, additional epidemiological data are required to determine if human lice
-
Johnson, Tanya L.; Waack, Ursula; Smith, Sara; Mobley, Harry
2015-01-01
ABSTRACT Gram-negative bacteria express a number of sophisticated secretion systems to transport virulence factors across the cell envelope, including the type II secretion (T2S) system. Genes for the T2S components GspC through GspN and PilD are conserved among isolates of Acinetobacter baumannii, an increasingly common nosocomial pathogen that is developing multidrug resistance at an alarming rate. In contrast to most species, however, the T2S genes are dispersed throughout the genome rather than linked into one or two operons. Despite this unique genetic organization, we show here that the A. baumannii T2S system is functional. Deletion of gspD or gspE in A. baumannii ATCC 17978 results in loss of secretion of LipA, a lipase that breaks down long-chain fatty acids. Due to a lack of extracellular lipase, the gspD mutant, the gspE mutant, and a lipA deletion strain are incapable of growth on long-chain fatty acids as a sole source of carbon, while their growth characteristics are indistinguishable from those of the wild-type strain in nutrient-rich broth. Genetic inactivation of the T2S system and its substrate, LipA, also has a negative impact on in vivo fitness in a neutropenic murine model for bacteremia. Both the gspD and lipA mutants are outcompeted by the wild-type strain as judged by their reduced numbers in spleen and liver following intravenous coinoculation. Collectively, our findings suggest that the T2S system plays a hitherto-unrecognized role in in vivo survival of A. baumannii by transporting a lipase that may contribute to fatty acid metabolism. IMPORTANCE Infections by multidrug-resistant Acinetobacter baumannii are a growing health concern worldwide, underscoring the need for a better understanding of the molecular mechanisms by which this pathogen causes disease. In this study, we demonstrated that A. baumannii expresses a functional type II secretion (T2S) system that is responsible for secretion of LipA, an extracellular lipase required for
-
Fernández Zenoff, V.; Siñeriz, F.; Farías, M. E.
2006-01-01
Acinetobacter johnsonii A2 isolated from the natural community of Laguna Azul (Andean Mountains at 4,560 m above sea level), Serratia marcescens MF42, Pseudomonas sp. strain MF8 isolated from the planktonic community, and Cytophaga sp. strain MF7 isolated from the benthic community from Laguna Pozuelos (Andean Puna at 3,600 m above sea level) were subjected to UV-B (3,931 J m−2) irradiation. In addition, a marine Pseudomonas putida strain, 2IDINH, and a second Acinetobacter johnsonii strain, ATCC 17909, were used as external controls. Resistance to UV-B and kinetic rates of light-dependent (UV-A [315 to 400 nm] and cool white light [400 to 700 nm]) and -independent reactivation following exposure were determined by measuring the survival (expressed as CFU) and accumulation of cyclobutane pyrimidine dimers (CPD). Significant differences in survival after UV-B irradiation were observed: Acinetobacter johnsonii A2, 48%; Acinetobacter johnsonii ATCC 17909, 20%; Pseudomonas sp. strain MF8, 40%; marine Pseudomonas putida strain 2IDINH, 12%; Cytophaga sp. strain MF7, 20%; and Serratia marcescens, 21%. Most bacteria exhibited little DNA damage (between 40 and 80 CPD/Mb), except for the benthic isolate Cytophaga sp. strain MF7 (400 CPD/Mb) and Acinetobacter johnsonii ATCC 17909 (160 CPD/Mb). The recovery strategies through dark and light repair were different in all strains. The most efficient in recovering were both Acinetobacter johnsonii A2 and Cytophaga sp. strain MF7; Serratia marcescens MF42 showed intermediate recovery, and in both Pseudomonas strains, recovery was essentially zero. The UV-B responses and recovery abilities of the different bacteria were consistent with the irradiation levels in their native environment. PMID:17056692
-
Braun, Graziela; Vidotto, Marilda Carlos
2004-12-01
Acinetobacter baumannii is a strictly aerobic bacterium which causes severe infections, however its pathogenic characteristics are not well defined. Thirteen A. baumannii strains isolated from urine of hospitalized and nonhospitalized patients with different ages were investigated for the presence of virulence factors. The isolates belonged to biotypes 2, 6, and 9 and were sensitive to imipenem. The majority of them showed resistance to amikacin, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, norfloxacin, and trimethoprim-sulfamethoxazole. None of A. baumannii strains presented genes codifying for 17 different virulence factors previously described in uropathogenic Escherichia coli, when tested by polymerase chain reaction (PCR). Nine isolates agglutinated human group AB erythrocytes, in presence of mannose, but none of them agglutinated group O erythrocytes. Adherence to polystyrene was observed in 7 isolates, and this result did not correlate with that obtained in hemagglutination assay. All the isolates were able to grow in iron-limiting conditions, showing that A. baumannii produces some type of siderophore. However, the genes iutA and fyuA, from iron uptake system of E. coli and Yersinia sp., respectively, were not present in the isolates, suggesting the presence of a different type of siderophore. The fimbriae of A. baumannii strains that mediates the adherence are possibly mannose-resistant, even though the mechanism of adherence to human epithelial cells still remains to be elucidated.
-
Peng, Fan; Mi, Zhiqiang; Huang, Yong; Yuan, Xin; Niu, Wenkai; Wang, Yahui; Hua, Yuhui; Fan, Huahao; Bai, Changqing; Tong, Yigang
2014-07-05
With the use of broad-spectrum antibiotics, immunosuppressive drugs, and glucocorticoids, multidrug-resistant Acinetobacter baumannii (MDR-AB) has become a major nosocomial pathogen species. The recent renaissance of bacteriophage therapy may provide new treatment strategies for combatting drug-resistant bacterial infections. In this study, we isolated a lytic bacteriophage vB_AbaM-IME-AB2 has a short latent period and a small burst size, which clear its host's suspension quickly, was selected for characterization and a complete genomic comparative study. The isolated bacteriophage vB_AbaM-IME-AB2 has an icosahedral head and displays morphology resembling Myoviridae family. Gel separation assays showed that the phage particle contains at least nine protein bands with molecular weights ranging 15-100 kDa. vB_AbaM-IME-AB2 could adsorb its host cells in 9 min with an adsorption rate more than 99% and showed a short latent period (20 min) and a small burst size (62 pfu/cell). It could form clear plaques in the double-layer assay and clear its host's suspension in just 4 hours. Whole genome of vB_AbaM-IME-AB2 was sequenced and annotated and the results showed that its genome is a double-stranded DNA molecule consisting of 43,665 nucleotides. The genome has a G + C content of 37.5% and 82 putative coding sequences (CDSs). We compared the characteristics and complete genome sequence of all known Acinetobacter baumannii bacteriophages. There are only three that have been sequenced Acinetobacter baumannii phages AB1, AP22, and phiAC-1, which have a relatively high similarity and own a coverage of 65%, 50%, 8% respectively when compared with our phage vB_AbaM-IME-AB2. A nucleotide alignment of the four Acinetobacter baumannii phages showed that some CDSs are similar, with no significant rearrangements observed. Yet some sections of these strains of phage are nonhomologous. vB_AbaM-IME-AB2 was a novel and unique A. baumannii bacteriophage. These findings suggest a common
-
Extrahuman Epidemiology of Acinetobacter baumannii in Lebanon
Rafei, Rayane; Hamze, Monzer; Pailhoriès, Hélène; Eveillard, Matthieu; Marsollier, Laurent; Joly-Guillou, Marie-Laure; Dabboussi, Fouad
2015-01-01
The presence of Acinetobacter baumannii outside hospitals is still a controversial issue. The objective of our study was to explore the extrahospital epidemiology of A. baumannii in Lebanon. From February 2012 to October 2013, a total of 73 water samples, 51 soil samples, 37 raw cow milk samples, 50 cow meat samples, 7 raw cheese samples, and 379 animal samples were analyzed by cultural methods for the presence of A. baumannii. Species identification was performed by rpoB gene sequencing. Antibiotic susceptibility was investigated, and the A. baumannii population was studied by two genotyping approaches: multilocus sequence typing (MLST) and blaOXA-51 sequence-based typing (SBT). A. baumannii was detected in 6.9% of water samples, 2.7% of milk samples, 8.0% of meat samples, 14.3% of cheese samples, and 7.7% of animal samples. All isolates showed a susceptible phenotype against most of the antibiotics tested and lacked carbapenemase-encoding genes, except one that harbored a blaOXA-143 gene. MLST analysis revealed the presence of 36 sequence types (STs), among which 24 were novel STs reported for the first time in this study. blaOXA-51 SBT showed the presence of 34 variants, among which 21 were novel and all were isolated from animal origins. Finally, 30 isolates had new partial rpoB sequences and were considered putative new Acinetobacter species. In conclusion, animals can be a potential reservoir for A. baumannii and the dissemination of new emerging carbapenemases. The roles of the novel animal clones identified in community-acquired infections should be investigated. PMID:25616788
-
Cordova-Rosa, S M; Dams, R I; Cordova-Rosa, E V; Radetski, M R; Corrêa, A X R; Radetski, C M
2009-05-15
Time-course performance of a phenol-degrading indigenous bacterial consortium, and of Acinetobacter calcoaceticus var. anitratus, isolated from an industrial coal wastewater treatment plant was evaluated. This bacterial consortium was able to survive in the presence of phenol concentrations as high as 1200mgL(-1) and the consortium was more fast in degrading phenol than a pure culture of the A. calcoaceticus strain. In a batch system, 86% of phenol biodegradation occurred in around 30h at pH 6.0, while at pH 3.0, 95.2% of phenol biodegradation occurred in 8h. A high phenol biodegradation (above 95%) by the mixed culture in a bioreactor was obtained in both continuous and batch systems, but when test was carried out in coke gasification wastewater, no biodegradation was observed after 10 days at pH 9-11 for both pure strain or the isolated consortium. An activated sludge with the same bacterial consortium characterized above was mixed with a textile sludge-contaminated soil with a phenol concentration of 19.48mgkg(-1). After 20 days of bioaugmentation, the remanescent phenol concentration of the sludge-soil matrix was 1.13mgkg(-1).
-
Halachev, Mihail R; Chan, Jacqueline Z-M; Constantinidou, Chrystala I; Cumley, Nicola; Bradley, Craig; Smith-Banks, Matthew; Oppenheim, Beryl; Pallen, Mark J
2014-01-01
Multidrug-resistant Acinetobacter baumannii commonly causes hospital outbreaks. However, within an outbreak, it can be difficult to identify the routes of cross-infection rapidly and accurately enough to inform infection control. Here, we describe a protracted hospital outbreak of multidrug-resistant A. baumannii, in which whole-genome sequencing (WGS) was used to obtain a high-resolution view of the relationships between isolates. To delineate and investigate the outbreak, we attempted to genome-sequence 114 isolates that had been assigned to the A. baumannii complex by the Vitek2 system and obtained informative draft genome sequences from 102 of them. Genomes were mapped against an outbreak reference sequence to identify single nucleotide variants (SNVs). We found that the pulsotype 27 outbreak strain was distinct from all other genome-sequenced strains. Seventy-four isolates from 49 patients could be assigned to the pulsotype 27 outbreak on the basis of genomic similarity, while WGS allowed 18 isolates to be ruled out of the outbreak. Among the pulsotype 27 outbreak isolates, we identified 31 SNVs and seven major genotypic clusters. In two patients, we documented within-host diversity, including mixtures of unrelated strains and within-strain clouds of SNV diversity. By combining WGS and epidemiological data, we reconstructed potential transmission events that linked all but 10 of the patients and confirmed links between clinical and environmental isolates. Identification of a contaminated bed and a burns theatre as sources of transmission led to enhanced environmental decontamination procedures. WGS is now poised to make an impact on hospital infection prevention and control, delivering cost-effective identification of routes of infection within a clinically relevant timeframe and allowing infection control teams to track, and even prevent, the spread of drug-resistant hospital pathogens.
-
First Genome Sequence of a Mexican Multidrug-Resistant Acinetobacter baumannii Isolate
Graña-Miraglia, Lucía; Lozano, Luis; Castro-Jaimes, Semiramis; Cevallos, Miguel A.; Volkow, Patricia
2016-01-01
Acinetobacter baumannii has emerged as an important nosocomial pathogen worldwide. Here, we present the draft genome of the first multidrug-resistant A. baumannii isolate, sampled from a tertiary hospital in Mexico City. This genome will provide a starting point for studying the genomic diversity of this species in Mexico. PMID:27013043
-
Wang, Peng; Bowler, Sarah L; Kantz, Serena F; Mettus, Roberta T; Guo, Yan; McElheny, Christi L; Doi, Yohei
2016-12-01
Treatment options for infections due to carbapenem-resistant Acinetobacter baumannii are extremely limited. Minocycline is a semisynthetic tetracycline derivative with activity against this pathogen. This study compared susceptibility testing methods that are used in clinical microbiology laboratories (Etest, disk diffusion, and Sensititre broth microdilution methods) for testing of minocycline, tigecycline, and doxycycline against 107 carbapenem-resistant A. baumannii clinical isolates. Susceptibility rates determined with the standard broth microdilution method using cation-adjusted Mueller-Hinton (MH) broth were 77.6% for minocycline and 29% for doxycycline, and 92.5% of isolates had tigecycline MICs of ≤2 μg/ml. Using MH agar from BD and Oxoid, susceptibility rates determined with the Etest method were 67.3% and 52.3% for minocycline, 21.5% and 18.7% for doxycycline, and 71% and 29.9% for tigecycline, respectively. With the disk diffusion method using MH agar from BD and Oxoid, susceptibility rates were 82.2% and 72.9% for minocycline and 34.6% and 34.6% for doxycycline, respectively, and rates of MICs of ≤2 μg/ml were 46.7% and 23.4% for tigecycline. In comparison with the standard broth microdilution results, very major rates were low (∼2.8%) for all three drugs across the methods, but major error rates were higher (∼5.6%), especially with the Etest method. For minocycline, minor error rates ranged from 14% to 37.4%. For tigecycline, minor error rates ranged from 6.5% to 69.2%. The majority of minor errors were due to susceptible results being reported as intermediate. For minocycline susceptibility testing of carbapenem-resistant A. baumannii strains, very major errors are rare, but major and minor errors overcalling strains as intermediate or resistant occur frequently with susceptibility testing methods that are feasible in clinical laboratories. Copyright © 2016, American Society for Microbiology. All Rights Reserved.
-
Koiwai, Kotaro; Hartmann, Marcus D.; Linke, Dirk; Lupas, Andrei N.; Hori, Katsutoshi
2016-01-01
Trimeric autotransporter adhesins (TAAs) on the cell surface of Gram-negative pathogens mediate bacterial adhesion to host cells and extracellular matrix proteins. However, AtaA, a TAA in the nonpathogenic Acinetobacter sp. strain Tol 5, shows nonspecific high adhesiveness to abiotic material surfaces as well as to biotic surfaces. It consists of a passenger domain secreted by the C-terminal transmembrane anchor domain (TM), and the passenger domain contains an N-terminal head, N-terminal stalk, C-terminal head (Chead), and C-terminal stalk (Cstalk). The Chead-Cstalk-TM fragment, which is conserved in many Acinetobacter TAAs, has by itself the head-stalk-anchor architecture of a complete TAA. Here, we show the crystal structure of the Chead-Cstalk fragment, AtaA_C-terminal passenger domain (CPSD), providing the first view of several conserved TAA domains. The YadA-like head (Ylhead) of the fragment is capped by a unique structure (headCap), composed of three β-hairpins and a connector motif; it also contains a head insert motif (HIM1) before its last inner β-strand. The headCap, Ylhead, and HIM1 integrally form a stable Chead structure. Some of the major domains of the CPSD fragment are inherently flexible and provide bending sites for the fiber between segments whose toughness is ensured by topological chain exchange and hydrophobic core formation inside the trimer. Thus, although adherence assays using in-frame deletion mutants revealed that the characteristic adhesive sites of AtaA reside in its N-terminal part, the flexibility and toughness of the CPSD part provide the resilience that enables the adhesive properties of the full-length fiber across a wide range of conditions. PMID:26698633
-
Acinetobacter Prosthetic Joint Infection Treated with Debridement and High-Dose Tigecycline.
Vila, Andrea; Pagella, Hugo; Amadio, Claudio; Leiva, Alejandro
2016-12-01
Prosthesis retention is not recommended for multidrug-resistant Acinetobacter prosthetic joint infection due to its high failure rate. Nevertheless, replacing the prosthesis implies high morbidity and prolonged hospitalization. Although tigecycline is not approved for the treatment of prosthetic joint infection due to multidrug resistant Acinetobacter baumannii, its appropriate use may preclude prosthesis exchange. Since the area under the curve divided by the minimum inhibitory concentration is the best pharmacodynamic predictor of its efficacy, we used tigecycline at high dose, in order to optimize its efficacy and achieve implant retention in 3 patients who refused prosthesis exchange. All patients with prosthetic joint infections treated at our Institution are prospectively registered in a database. Three patients with early prosthetic joint infection of total hip arthroplasty due to multidrug resistant A. baumannii were treated with debridement, antibiotics and implant retention, using a high maintenance dose of tigecycline (100 mg every 12 hours). The cases were retrospectively reviewed. All patients signed informed consent for receiving off-label use of tigecycline. Tigecycline was well tolerated, allowing its administration at high maintenance dose for a median of 40 days (range 30-60). Two patients were then switched to minocycline at standard doses for a median of 3.3 months in order to complete treatment. Currently, none of the patients showed relapse. Increasing the dose of tigecycline could be considered as a means to better attain pharmacodynamic targets in patients with severe or difficult-to-treat infections. Tigecycline at high maintenance dose might be useful when retention of the implant is attempted for treatment for prosthetic joint infections due to multidrug resistant Acinetobacter. Although this approach might be promising, off-label use of tigecycline should be interpreted cautiously until prospective data are available. Tigecycline is
-
Abdalla, Nazar M; Osman, Amani A; Haimour, Waleed O; Sarhan, Mohammed A A; Mohammed, Mohammed N; Zyad, Eyhab M; Al-Ghtani, Abdalla M
2013-03-15
This study aimed at evaluating the sensitivity of antibiotics towards nosocomial infections caused by Acinetobacter species. The study took place during the period Dec. 2011- Dec. 2012 at Assir Central Hospital in collaboration with the department of microbiology, college of medicine, King Khalid University, Abha. A prospective study involving 150 patients presented with nosocomial infections due to Acinetobacter species detected by bacteriological tests; direct microscopy, culture in blood agar media, fermentation test in MacConkey media and MIC (minimum inhibitory concentration) for antibiotics sensitivity using Muller Hinton media and Chemical test using API 20. A 150 nosocomial infections in this study showed gram-negative coccobacilli, non motile, glucose-negative fermentor and oxidase negative. All isolates showed 100% sensitivity to: Imipramine, Meropenem, Colistin. From the rest of tested antibiotics the higher resistant ones were; Nitrofurantoin 87% and Cefoxitin 85%. The least resistant antibiotics; Imipenem 3% and Ticarcillin 7%. While variable resistance in the rest of tested antimicrobials. A 47 patients (31.3%) have used antibiotics prior to this study. The high rate of usage occurred in elder patients. The frequency of Acinetobacter calcoaceticus baumannii complex multi-drugs resistance ABCMDR is rising including almost all commonly used antibiotics. Only few antibiotics exert 100% sensitivity towards these bacteria.
-
Tuan, Nguyen Ngoc; Lin, Yi-Wen; Huang, Shir-Ly
2013-03-01
In this study, a specific PCR primer set was successfully designed for alkylcatechol 2, 3-dioxygenase genes and applied to detect the presence of this biomarker in 4-t-octylphenol-degrading Acinetobacter sp. strain OP5. A gene cluster (ophRBA1A2A3A4A5A6CEH) encoding multicomponent phenol hydroxylase and alkylcatechol 2, 3-dioxygenase was then cloned from this strain and showed the highest homology to those involved in the published medium-chain alkylphenol gene clusters. The pure enzyme of recombinant cell harboring ophB showed meta-cleavage activities for 4-methylcatechol (1,435%), 4-ethylcatechol (982%), catechol (100%), 4-t-butylcatechol (16.6%), and 4-t-octylcatechol (3.2%). The results suggest that the developed molecular technique is useful and easy in detection of medium/long-chain alkylphenol degradation gene cluster. In addition, it also provides a better understanding of the distribution of biodegradative genes and pathway for estrogenic-active long-chain alkylphenols in bacteria. Copyright © 2013 Elsevier Ltd. All rights reserved.
-
Co-biodegradation of anthracene and naphthalene by the bacterium Acinetobacter johnsonii.
Jiang, Yan; Qi, Hui; Zhang, Xian M
2018-04-16
NAP (Naphthalene) and ANT (anthracene) usually co-exist in environment and possessed interactional effects on their biodegradation in environment. Presently, a strain of Acinetobacter johnsonii was employed to degrade NAP and ANT in single- and dual-substrate systems. NAP was utilized as prefer substrate by cells to accelerate ANT biodegradation. As much as 200 mg L -1 ANT could be entirely degraded with 1,500 mg L -1 NAP, which was beyond bacterial potential in single substrate system. Especially, the shortest biodegradation period (103 h) for ANT was observed with the presence of 50 mg L -1 NAP. By contrast, ANT showed strong inhibition on NAP degradation, while the peak biodegradation of 1,950 mg L -1 NAP with 50 mg L -1 ANT could still proceed. By introducing an inhibition constant parameter to fit the inhibition on cells, modeling indicated the substrate inhibition for NAP and ANT over the concentrations of 174 and 49 mg L -1 , respectively. Furthermore, enzyme assay revealed the pathway of meta fission in NAP biodegradation due to the appearance of catechol 2,3-dioxygenase activity, and low-level lipase excretion was also found in both NAP and ANT biodegradation, but hardly affect NAP and ANT biodegradation in the present study. To research the interplay of NAP and ANT is conducive to targeted decontamination.
-
Gu, Qihui; Wu, Qingping; Zhang, Jumei; Guo, Weipeng; Wu, Huiqing; Sun, Ming
2017-07-07
Phenol is a hazardous chemical known to be widely distributed in aquatic environments. Biodegradation is an attractive option for removal of phenol from water sources. Acinetobacter sp. DW-1 isolated from drinking water biofilters can use phenol as a sole carbon and energy source. In this study, we found that Immobilized Acinetobacter sp. DW-1cells were effective in biodegradation of phenol. In addition, we performed proteome and transcriptome analysis of Acinetobacter sp. DW-1 during phenol biodegradation. The results showed that Acinetobacter sp. DW-1 degrades phenol mainly by the ortho pathway because of the induction of phenol hydroxylase, catechol-1,2-dioxygenase. Furthermore, some novel candidate proteins (OsmC-like family protein, MetA-pathway of phenol degradation family protein, fimbrial protein and coenzyme F390 synthetase) and transcriptional regulators (GntR/LuxR/CRP/FNR/TetR/Fis family transcriptional regulator) were successfully identified to be potentially involved in phenol biodegradation. In particular, MetA-pathway of phenol degradation family protein and fimbrial protein showed a strong positive correlation with phenol biodegradation, and Fis family transcriptional regulator is likely to exert its effect as activators of gene expression. This study provides valuable clues for identifying global proteins and genes involved in phenol biodegradation and provides a fundamental platform for further studies to reveal the phenol degradation mechanism of Acinetobacter sp.
-
Ertürk, Ayşe; Çiçek, Ayşegül Çopur; Gümüş, Aziz; Cüre, Erkan; Şen, Ahmet; Kurt, Aysel; Karagöz, Alper; Aydoğan, Nebahat; Sandallı, Cemal; Durmaz, Rıza
2014-07-22
A nosocomial outbreak of Acinetobacter baumannii (AB) infections occurred among intensive care units (ICU) (surgery, medical, cardiovascular surgery, coronary unit) of Recep Tayyip Erdogan University Medical School (Rize, Turkey) between January 2011 and May 2012. The identification of isolates and clonal relation among them were investigated by molecular techniques. A total of 109 AB isolates were obtained from 64 clinical materials from 54 ICU patients and 3 from the hands of healthcare workers (HCWs) of 42 environmental samples. The isolates were identified by 16S rDNA sequencing and OXA- specific PCR. The clonal relation between isolates was investigated by PFGE methods using ApaI restriction enzyme. All isolates were determined as AB by 16S rDNA sequencing and OXA-spesific PCR. While the blaOXA-51-like gene was amplified in all isolates, the blaOXA-23-like gene was amplified from 103 isolates. The PFGE pattern generated 9 pulsotypes and showed that the isolates from patients, HCWs, and the environment were genetically related. In 7 of these pulsotypes, there were 107 strains (98%) showing similar PFGE profiles that cannot be distinguished from each other, ranging from 2 to 53. The remaining 2 pulsotypes were comprised of strains closely associated with the main cluster. Two major groups were discovered with similarity coefficient of 85% and above. The first group consisted of 97 strains that are similar to each other at 92.7% rate, and the second group consisted of 12 strains that are 100% identical. The common utilization of the blood gas device among ICU was the reason for the contamination. AB strains can remain stable for a long period of time, although due to the disinfection procedures applied in hospitals, there is a small chance that the same clone might reappear and cause another epidemic. For that reason, the resistance profiles of the strains must be continuously followed with amplification-based methods, and these methods should be used to support
-
Kulkarni, Raghavendra D.; Mishra, Mukti Nath; Mohanraj, Jeevanandam; Chandrasekhar, Arun; Ajantha, G. S.; Kulkani, Sheetal; Bhat, Shama
2018-01-01
BACKGROUND: Nosocomial infections are often caused by multidrug-resistant bacteria and the incidence is increasing. Acinetobacter, a Gram-negative bacillus, is commonly associated with the use of intravascular catheterization and airway intubation. Polymerase chain reaction (PCR) for identification of Acinetobacter baumannii from samples has been standardized that use conventional wet-reagent mix. We have designed and optimized a dry-reagent mix for identification of Acinetobacter species by PCR. The dry-reagent mix can be stored at room temperature, has less chances of contamination, and thus can be used at point-of-care diagnosis. AIM AND OBJECTIVE: The present work was focused on comparing the sensitivity and specificity of dry-reagent PCR mix over conventional wet-reagent PCR mix for identification of Acinetobacter species. MATERIALS AND METHODS: Conventional wet-reagent mix based and dry-reagent mix based PCR were carried out for the DNA isolated from Acinetobacter species. The latter was also applied directly on bacterial growth without prior DNA extraction process. Equal numbers of bacterial isolates other than Acinetobacter species were also subjected to identification by the same protocols for determining the sensitivity and specificity of the test. RESULTS: The Acinetobacter species showed amplification of the target rpoB gene and the band was observed at 397 bp. The dry-reagent PCR mix results matched completely with the conventional wet-reagent PCR mix assay. All the non-Acinetobacter isolates were negative for the PCR. This indicates that the test is highly specific. The dry-reagent mix also contained an enzyme resistant to PCR inhibitors and capable of amplifying DNA directly from cells. CONCLUSION: Performance of dry-reagent PCR mix without the need for DNA extraction and preparation of a PCR mix proved to be more sensitive and reduce the handling error, minimizes the time, manual work, and skilled labor. PMID:29403209
-
Suzuki, Wakako; Sugawara, Masayuki; Miwa, Kyoko; Morikawa, Masaaki
2014-07-01
Acinetobacter calcoaceticus P23 is a plant growth-promoting bacterium that was isolated from the surface of duckweed (Lemna aoukikusa). The bacterium was observed to colonize on the plant surfaces and increase the chlorophyll content of not only the monocotyledon Lemna minor but also the dicotyledon Lactuca sativa in a hydroponic culture. This effect on the Lactuca sativa was significant in nutrient-poor (×1/100 dilution of H2 medium) and not nutrient-rich (×1 or ×1/10 dilutions of H2 medium) conditions. Strain P23 has the potential to play a part in the future development of fertilizers and energy-saving hydroponic agricultural technologies. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
-
Liu, Yongjun; Gao, Min; Zhang, Aining; Liu, Zhe
2017-07-01
In order to strengthen the aerobic digestion of residual sludge, shorten the time of sludge stabilization and further reduce operating costs, 3 dominant strains identified as Pseudomonas sp. L3, Acinetobacter sp. L16 and Bacillus sp. L19 were isolated from long-term aerobic digestion sludge. Results showed that the sludge stabilization time were reduced by 3-4days compared with the control when the dominant strains were added to the process of sludge aerobic digestion. The addition of dominant strains accelerated the accumulation of TOC, nitrate nitrogen and ammonia nitrogen in the digestive solution at different levels, and it was beneficial to the dissolution of phosphorus. Controlling DO 3-5mg/L, pH 6.5, the strains of Pseudomonas sp. L3 and Bacillus sp. L19 were combined dosing with the dosage of 2% in the process of sludge aerobic digestion, compared with the control, digestion rates of TOC and MLSS were increased about 19% and 16%, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.
-
Zhang, Chuanfu; Qiu, Shaofu; Wang, Yong; Qi, Lihua; Hao, Rongzhang; Liu, Xuelin; Shi, Yun; Hu, Xiaofeng; An, Daizhi; Li, Zhenjun; Li, Peng; Wang, Ligui; Cui, Jiajun; Wang, Pan; Huang, Liuyu; Klena, John D; Song, Hongbin
2014-01-01
Multidrug resistant microbes present in the environment are a potential public health risk. In this study, we investigate the presence of New Delhi metallo-β-lactamase 1 (NDM-1) producing bacteria in the 99 water samples in Beijing City, including river water, treated drinking water, raw water samples from the pools and sewage from 4 comprehensive hospitals. For the bla NDM-1 positive isolate, antimicrobial susceptibility testing was further analyzed, and Pulsed Field Gel Electrophoresis (PFGE) was performed to determine the genetic relationship among the NDM-1 producing isolates from sewage and human, as well as the clinical strains without NDM-1. The results indicate that there was a higher isolation of NDM-1 producing Acinetobacter baumannii from the sewage of the hospitals, while no NDM-1 producing isolates were recovered from samples obtained from the river, drinking, or fishpond water. Surprisingly, these isolates were markedly different from the clinical isolates in drug resistance and pulsed field gel electrophoresis profiles, suggesting different evolutionary relationships. Our results showed that the hospital sewage may be one of the diffusion reservoirs of NDM-1 producing bacteria.
-
Wang, Dalin; Ma, Linlin; Wu, Zhenyu; Li, Mingcheng; Li, Xiaohan; Zhang, Wei; Chen, Kun
2015-03-01
The aim of this study was to investigate the prevalence and characteristics of imipenem-resistant Acinetobacter baumanni isolated from surgical wards in a university hospital, China. A total of 143 non-duplicate A. baumannii were isolated from 517 inpatients in surgery intensive care units (ICUs), burn wards, and general surgery wards. Of these, 102 isolates of A. baumannii (71.3%) were resistant to imipenem. Among imipenem-resistant isolates, all isolates were resistant to almost all antimicrobial agents except polymyxin E, all isolates were positive for blaOXA-23 and blaOXA-51 in addition to ISAba1, 52 (51%) were positive for blaOXA-58, 8 (7.8%) contained blaVIM-2, which co-harbored with blaOXA-58. Molecular typing revealed the presence of three clones among imipenem-resistant isolates. This study confirmed that A. baumannii strains harboring OXA or VIM type β-lactamases are widely distributed throughout the surgery wards. The data demonstrate that there was a high prevalence of imipenem-resistant A. baumannii infection in the region.
-
Rafei, Rayane; Dabboussi, Fouad; Hamze, Monzer; Eveillard, Matthieu; Lemarié, Carole; Mallat, Hassan; Rolain, Jean-Marc; Joly-Guillou, Marie-Laure; Kempf, Marie
2014-04-01
The emergence of carbapenem-resistant Acinetobacter baumannii has been observed worldwide. We describe the first detection of A. baumannii carrying the blaNDM-1 gene in Lebanon, isolated from Syrian patients wounded during the civil war. Four carbapenem-resistant A. baumannii strains isolated in 2012 in the Tripoli Government Hospital, Lebanon, from civilians wounded during the Syrian war, were analysed. Susceptibility was determined by disk diffusion testing, and resistance to carbapenems was confirmed by Etest. The presence of blaOXA-23-like, blaOXA-24-like, blaOXA-58-like, blaOXA-143-like, and blaNDM was investigated by PCR. Clonal relationships were studied by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and blaOXA-51 sequence-based typing. All isolates harboured the blaNDM-1 gene and were negative for other tested carbapenemases. They all belonged to the sequence type 85 and formed a single cluster by PFGE. Finally, blaOXA-51-like gene sequencing revealed the presence of the blaOXA-94 variant in all four isolates. These findings show that Syria constitutes a reservoir for NDM-1-producing bacteria. These results also highlight the need for effective measures to stop the threatening spread of such strains. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.
-
Leski, Tomasz A.; Stockelman, Michael G.; Craft, David W.; Zurawski, Daniel V.; Kirkup, Benjamin C.; Vora, Gary J.
2014-01-01
Multidrug-resistant (MDR) Acinetobacter baumannii infections are of particular concern within medical treatment facilities, yet the gene assemblages that give rise to this phenotype remain poorly characterized. In this study, we tested 97 clinical A. baumannii isolates collected from military treatment facilities (MTFs) from 2003 to 2009 by using a molecular epidemiological approach that enabled for the simultaneous screening of 236 antimicrobial resistance genes. Overall, 80% of the isolates were found to be MDR, each strain harbored between one and 17 resistant determinants, and a total of 52 unique resistance determinants or gene families were detected which are known to confer resistance to β-lactam (e.g., blaGES-11, blaTEM, blaOXA-58), aminoglycoside (e.g., aphA1, aacC1, armA), macrolide (msrA, msrB), tetracycline [e.g., tet(A), tet(B), tet(39)], phenicol (e.g., cmlA4, catA1, cat4), quaternary amine (qacE, qacEΔ1), streptothricin (sat2), sulfonamide (sul1, sul2), and diaminopyrimidine (dfrA1, dfrA7, dfrA19) antimicrobial compounds. Importantly, 91% of the isolates harbored blaOXA-51-like carbapenemase genes (including six new variants), 40% harbored the blaOXA-23 carbapenemase gene, and 89% contained a variety of aminoglycoside resistance determinants with up to six unique determinants identified per strain. Many of the resistance determinants were found in potentially mobile gene cassettes; 45% and 7% of the isolates contained class 1 and class 2 integrons, respectively. Combined, the results demonstrate a facile approach that supports a more complete understanding of the genetic underpinnings of antimicrobial resistance to better assess the load, transmission, and evolution of MDR in MTF-associated A. baumannii. PMID:24247131
-
First report of OXA-143-lactamase producing Acinetobacter baumannii in Qom, Iran.
Sarikhani, Zohreh; Nazari, Razieh; Nateghi Rostami, Mahmoud
2017-11-01
Antibiotic resistance in Acinetobacter baumannii and outbreaks caused by this organism have been reported from several areas of the world. The present study aimed at determining the antibiotic susceptibility profiles and the distribution of OXA-type beta-lactamases among Iranian Acinetobacter baumannii isolates from Qom of Iran. For this study, 108 non-duplicate A. baumannii isolates were obtained from clinical specimens in four teaching hospitals in Qom in the central of Iran. The antimicrobial susceptibility of isolates was tested by standard disk diffusion and prevalence of bla OXA genes was investigated by PCR method. Among 97 carbapenem non-susceptible isolates of A. baumannii , 90.72% (88 isolates) isolates showed extensive drug resistance to multiple antibiotics. Among carbapenem resistant isolates, 100% carried bla OXA-51-like , 82.47% carried bla OXA-23-like , 55.67% carried bla OXA-58-like , 22.68% carried bla OXA-40-like and 14.43% had bla OXA-143-like resistance genes. This study demonstrated high genetic diversity of OXA genes among isolates of A. baumannii in Qom, Iran.
-
First report of OXA-143-lactamase producing Acinetobacter baumannii in Qom, Iran
Sarikhani, Zohreh; Nazari, Razieh; Nateghi Rostami, Mahmoud
2017-01-01
Objective(s): Antibiotic resistance in Acinetobacter baumannii and outbreaks caused by this organism have been reported from several areas of the world. The present study aimed at determining the antibiotic susceptibility profiles and the distribution of OXA-type beta-lactamases among Iranian Acinetobacter baumannii isolates from Qom of Iran. Materials and Methods: For this study, 108 non-duplicate A. baumannii isolates were obtained from clinical specimens in four teaching hospitals in Qom in the central of Iran. The antimicrobial susceptibility of isolates was tested by standard disk diffusion and prevalence of bla OXA genes was investigated by PCR method. Results: Among 97 carbapenem non-susceptible isolates of A. baumannii, 90.72% (88 isolates) isolates showed extensive drug resistance to multiple antibiotics. Among carbapenem resistant isolates, 100% carried blaOXA-51-like, 82.47% carried blaOXA-23-like, 55.67% carried blaOXA-58-like, 22.68% carried blaOXA-40-like and 14.43% had blaOXA-143-like resistance genes. Conclusion: This study demonstrated high genetic diversity of OXA genes among isolates of A. baumannii in Qom, Iran. PMID:29299207
-
Silambarasan, Sivagnanam; Vangnai, Alisa S
2016-01-25
4-nitroaniline (4-NA) is one of the major priority pollutants generated from industrial productions and pesticide transformation; however very limited biodegradation details have been reported. This work is the first to report 4-NA biodegradation kinetics and toxicity reduction using a newly isolated plant-growth promoting bacterium, Acinetobacter sp. AVLB2. The 4-NA-dependent growth kinetics parameters: μmax, Ks and Ki, were determined to be 0.039 h(-1), 6.623 mg L(-1) and 25.57 mg L(-1), respectively using Haldane inhibition model, while the maximum biodegradation rate (Vmax) of 4-NA was at 0.541 mg L(-1) h(-1) and 0.551 mg L(-1) h(-1), following Michaelis-Menten and Hanes-Woolf models, respectively. Biodegradation pathway of 4-NA by Acinetobacter sp. AVLB2 was proposed, and successfully led to the reduction of 4-NA toxicity according to the following toxicity assessments: microbial toxicity using Escherichia coli DH5α, phytotoxicity with Vigna radiata and Crotalaria juncea, and cytogenotoxicity with Allium cepa root-tip cells. In addition, Acinetobacter sp. AVLB2 possess important plant-growth promoting traits, both in the presence and absence of 4-NA. This study has provided a new insight into 4-NA biodegradation ability and concurrent plant-growth promoting activities of Acinetobacter sp. AVLB2, which may indicate its potential role for rhizoremediation, while sustaining crop production even under 4-NA stressed environment. Copyright © 2015 Elsevier B.V. All rights reserved.
-
Zenati, K; Touati, A; Bakour, S; Sahli, F; Rolain, J M
2016-01-01
Investigation of several outbreaks of multidrug-resistant Acinetobacter baumannii infection has demonstrated that contamination of the inanimate hospital environment could be implicated in the spread of these multidrug-resistant strains. To investigate the occurrence of carbapenem-resistant A. baumannii on inanimate surfaces and possible dissemination in the hospital environment in Algeria as a potential source of infection in humans. A. baumannii strains were isolated from the hospital environment and identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Antimicrobial susceptibility was determined using disc diffusion and E-test methods. Carbapenemase activity was detected using microbiological tests, including modified Hodge test, modified Carba NP test, and EDTA test. Carbapenem resistance determinants were studied by polymerase chain reaction (PCR) and sequencing. Clonal relatedness was determined using multi-locus sequence typing (MLST). A total of 67 A. baumannii isolates were obtained from 868 environmental samples and identified by MALDI-TOF MS. Among them, 61 isolates were resistant to imipenem with minimum inhibitory concentration >32 μg/mL and positive by the modified Hodge test and modified Carba NP test. In addition, the activity of carbapenemase was inhibited by EDTA in 32 strains. PCR and sequencing showed the presence of blaOXA-23 gene in 29 strains, and the blaNDM-1 gene in 32 isolates. MLST demonstrated the presence of five types of ST (ST19, ST2, ST85, ST98, and ST115). Our study demonstrated the dissemination of carbapenemase-producing A. baumannii strains recovered from inanimate surfaces in a hospital environment, surrounding patients, healthcare workers and visitors, in Algeria as a potential source for nosocomial infection. Copyright © 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
-
Su, Jun Feng; Liang, Dong Hui; Huang, Ting Lin; Wei, Li; Ma, Min; Lu, Jinsuo
2017-07-01
In this study, immobilization technique was employed to improve simultaneous algicidal and denitrification of immobilized Acinetobacter sp. J25 with magnetic Fe 3 O 4 in eutrophic landscape water. After 7 days of operation, the maximum superoxide dismutase (SOD) activity (54.43 U mg -1 ), nitrate removal efficiency (100% (0.2127 mg L -1 h -1 )), and chlorophyll-a removal efficiency (89.71%) were obtained from the immobilized J25 with magnetic Fe 3 O 4 . The results suggest that immobilized J25 with magnetic Fe 3 O 4 had better nitrogen removal efficiency and algicidal activity in eutrophic landscape water. High-throughput sequencing data profiled the strain J25 that was immobilized with magnetic Fe 3 O 4 which changed the composition of the microbial community. The results indicated a novel concept of enhancing the algicidal and denitrification property of immobilized bacteria with magnetic Fe 3 O 4 in eutrophic landscape water.
-
Use of the accessory genome for characterization and typing of Acinetobacter baumannii.
Turton, Jane F; Baddal, Buket; Perry, Claire
2011-04-01
Outbreak strains of Acinetobacter baumannii are highly clonal, and cross-infection investigations can be difficult. We sought targets based on AbaR resistance islands and on other genes found in some, but not all, sequenced isolates of A. baumannii among a set of clinical isolates (n = 70) that included multiple representatives of a number of pulsed-field gel electrophoresis (PFGE)-defined types. These included representatives that varied in their profiles at two variable-number tandem repeat (VNTR) loci, which can provide discrimination within a PFGE cluster. Detection, or not, of each element sought provided some degree of discrimination among the set, with the presence or absence of genes coding for a phage terminase (ACICU_02185), a sialic acid synthase (ACICU_00080), a polysaccharide biosynthesis protein (AB57_0094), aphA1, bla(TEM), and integron-associated orfX (Kyoto Encyclopedia of Genes and Genomes [KEGG] no. K03830) proving the most helpful in discriminating between closely related isolates in our panel. The results support VNTR data in describing distinct populations of highly similar isolates. Such analysis, in combination with other typing methods, can inform epidemiological investigations and provide additional characterization of isolates. Most genotypes carrying bla(OXA-23-like) were PCR positive for a yeeA-bla(OXA-23) fragment found in an AbaR4-type island, suggesting that this is widespread.
-
Intorasoot, Amornrat; Chornchoem, Piyaorn; Sookkhee, Siriwoot; Intorasoot, Sorasak
2017-01-01
Aim: The aim of the study is to investigate the antibacterial activity of 10 volatile oils extracted from medicinal plants, including galangal (Alpinia galanga Linn.), ginger (Zingiber officinale), plai (Zingiber cassumunar Roxb.), lime (Citrus aurantifolia), kaffir lime (Citrus hystrix DC.), sweet basil (Ocimum basilicum Linn.), tree basil (Ocimum gratissimum), lemongrass (Cymbopogon citratus DC.), clove (Syzygium aromaticum), and cinnamon (Cinnamomum verum) against four standard strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and 30 clinical isolates of multidrug-resistant A. baumannii (MDR-A. baumannii). Materials and Methods: Agar diffusion, minimum inhibitory concentration, and minimum bactericidal concentration (MBC) were employed for the determination of bactericidal activity of water distilled medicinal plants. Tea tree oil (Melaleuca alternifolia) was used as positive control in this study. Results: The results indicated the volatile oil extracted from cinnamon exhibited potent antibacterial activity against the most common human pathogens, S. aureus, E. coli, P. aeruginosa, and A. baumannii. Most of volatile oil extracts were less effective against non-fermentative bacteria, P. aeruginosa. In addition, volatile oil extracted from cinnamon, clove, and tree basil possessed potent bactericidal activity against MDR-A. baumannii with MBC90 of 0.5, 1, and 2 mg/mL, respectively. Conclusions: The volatile oil extracts would be useful as alternative natural product for the treatment of the most common human pathogens and MDR-A. baumannii infections. PMID:28512603
-
Intorasoot, Amornrat; Chornchoem, Piyaorn; Sookkhee, Siriwoot; Intorasoot, Sorasak
2017-01-01
The aim of the study is to investigate the antibacterial activity of 10 volatile oils extracted from medicinal plants, including galangal ( Alpinia galanga Linn.), ginger ( Zingiber officinale ), plai ( Zingiber cassumunar Roxb.), lime ( Citrus aurantifolia ), kaffir lime ( Citrus hystrix DC.), sweet basil ( Ocimum basilicum Linn.), tree basil ( Ocimum gratissimum ), lemongrass ( Cymbopogon citratus DC.), clove ( Syzygium aromaticum ), and cinnamon ( Cinnamomum verum ) against four standard strains of Staphylococcus aureus , Escherichia coli , Pseudomonas aeruginosa , Acinetobacter baumannii , and 30 clinical isolates of multidrug-resistant A. baumannii (MDR- A. baumannii ). Agar diffusion, minimum inhibitory concentration, and minimum bactericidal concentration (MBC) were employed for the determination of bactericidal activity of water distilled medicinal plants. Tea tree oil ( Melaleuca alternifolia ) was used as positive control in this study. The results indicated the volatile oil extracted from cinnamon exhibited potent antibacterial activity against the most common human pathogens, S. aureus , E. coli , P. aeruginosa , and A. baumannii . Most of volatile oil extracts were less effective against non-fermentative bacteria, P. aeruginosa . In addition, volatile oil extracted from cinnamon, clove, and tree basil possessed potent bactericidal activity against MDR- A. baumannii with MBC 90 of 0.5, 1, and 2 mg/mL, respectively. The volatile oil extracts would be useful as alternative natural product for the treatment of the most common human pathogens and MDR- A. baumannii infections.
-
Minerdi, Daniela; Zgrablic, Ivan; Castrignanò, Silvia; Catucci, Gianluca; Medana, Claudio; Terlizzi, Maria Elena; Gribaudo, Giorgio; Gilardi, Gianfranco
2015-01-01
Antimicrobial resistance is a global issue currently resulting in the deaths of hundreds of thousands of people a year worldwide. Data present in the literature illustrate the emergence of many bacterial species that display resistance to known antibiotics; Acinetobacter spp. are a good example of this. We report here that Acinetobacter radioresistens has a Baeyer-Villiger monooxygenase (Ar-BVMO) with 100% amino acid sequence identity to the ethionamide monooxygenase of multidrug-resistant (MDR) Acinetobacter baumannii. Both enzymes are only distantly phylogenetically related to other canonical bacterial BVMO proteins. Ar-BVMO not only is capable of oxidizing two anticancer drugs metabolized by human FMO3, danusertib and tozasertib, but also can oxidize other synthetic drugs, such as imipenem. The latter is a member of the carbapenems, a clinically important antibiotic family used in the treatment of MDR bacterial infections. Susceptibility tests performed by the Kirby-Bauer disk diffusion method demonstrate that imipenem-sensitive Escherichia coli BL21 cells overexpressing Ar-BVMO become resistant to this antibiotic. An agar disk diffusion assay proved that when imipenem reacts with Ar-BVMO, it loses its antibiotic property. Moreover, an NADPH consumption assay with the purified Ar-BVMO demonstrates that this antibiotic is indeed a substrate, and its product is identified by liquid chromatography-mass spectrometry to be a Baeyer-Villiger (BV) oxidation product of the carbonyl moiety of the β-lactam ring. This is the first report of an antibiotic-inactivating BVMO enzyme that, while mediating its usual BV oxidation, also operates by an unprecedented mechanism of carbapenem resistance. PMID:26459905
-
Tängdén, Thomas; Karvanen, Matti; Friberg, Lena E; Odenholt, Inga; Cars, Otto
2017-07-01
In view of the paucity of clinical evidence, in vitro studies are needed to find antibiotic combinations effective against multidrug-resistant Gram-negative bacteria. Interpretation of in vitro effects is usually based on bacterial growth after 24 h in time-kill and checkerboard experiments. However, the clinical relevance of the effects observed in vitro is not established. In this study we explored alternative output parameters to assess the activities of colistin and meropenem against Pseudomonas aeruginosa and Acinetobacter baumannii. Four strains each of P. aeruginosa and A. baumannii were exposed to colistin and meropenem, alone and in combination, in 8 h dynamic time-kill experiments. Initial (1 h), maximum and 8 h bacterial reductions and the area under the bacterial time-kill curve were evaluated. Checkerboards, interpreted based on fractional inhibitory concentration indices after 24 h, were performed for comparison. In the time-kill experiments, the combination resulted in enhanced 1 h, maximum and 8 h bacterial reductions against 2, 3 and 5 of 8 strains, respectively, as compared to the single drugs. A statistically significant reduction in the area under the time-kill curve was observed for three strains. In contrast, the checkerboards did not identify synergy for any of the strains. Combination effects were frequently found with colistin and meropenem against P. aeruginosa and A. baumannii in time-kill experiments but were not detected with the checkerboard method. We propose that the early dynamics of bacterial killing and growth, which may be of great clinical importance, should be considered in future in vitro combination studies.
-
Nero, Thomas M; Dalia, Triana N; Wang, Joseph Che-Yen; Kysela, David T; Bochman, Matthew L; Dalia, Ankur B
2018-05-02
Acquisition of foreign DNA by natural transformation is an important mechanism of adaptation and evolution in diverse microbial species. Here, we characterize the mechanism of ComM, a broadly conserved AAA+ protein previously implicated in homologous recombination of transforming DNA (tDNA) in naturally competent Gram-negative bacterial species. In vivo, we found that ComM was required for efficient comigration of linked genetic markers in Vibrio cholerae and Acinetobacter baylyi, which is consistent with a role in branch migration. Also, ComM was particularly important for integration of tDNA with increased sequence heterology, suggesting that its activity promotes the acquisition of novel DNA sequences. In vitro, we showed that purified ComM binds ssDNA, oligomerizes into a hexameric ring, and has bidirectional helicase and branch migration activity. Based on these data, we propose a model for tDNA integration during natural transformation. This study provides mechanistic insight into the enigmatic steps involved in tDNA integration and uncovers the function of a protein required for this conserved mechanism of horizontal gene transfer.
-
Gao, Y; Yu, X Z; Wu, S C; Cheung, K C; Tam, N F Y; Qian, P Y; Wong, M H
2006-12-15
The effects of cultivation of rice (Oryza sativa L.) and PAH-degrading bacteria (Acinetobacter sp.) separately, and in combination, on the dissipation of spiked phenanthrene and pyrene (0, 50+50, 100+100, 200+200 mg kg(-1)) in waterlogged soil were studied using pot trials. The population of introduced PAH-degrading bacteria remained at 10(5) CFU g(-1) dry soil after 20 days of treatment with Acinetobacter sp. only, but increased to 10(6) when planted with rice simultaneously. Shoot and root biomass of rice when grown alone was adversely affected by spiked PAHs, but significantly increased by 2-55% and 8-409%, respectively, when inoculated with Acinetobacter sp.. Phenanthrene and pyrene concentrations in roots ranged from 1-27 and 20-98 mg kg(-1), respectively, while their concentrations in shoots were generally lower than 0.2 mg kg(-1). The dissipation of phenanthrene was mainly due to abiotic loss as 70-78% phenanthrene was lost from the control soil at the end of 80 days, while removal of 86-87% phenanthrene had been achieved after 40 days in the treatment co-cultivated with Acinetobacter sp. and rice. Compared with the control where only 6-15% of pyrene was removed from soil, a much higher dissipation of pyrene (43-62%) was attained for the treatments co-cultivated with Acinetobacter sp. and rice at the end of 80 days. The results demonstrated that co-cultivation of rice and PAH-degrading bacteria may have a great potential to accelerate the bioremediation process of PAH-contaminated soil under waterlogged conditions.
-
Adaptation to Potassium-Limitation Is Essential for Acinetobacter baumannii Pneumonia Pathogenesis.
Samir, Reham; Hussein, Salma H; Elhosseiny, Noha M; Khattab, Marwa S; Shawky, Alaa E; Attia, Ahmed S
2016-12-15
Acinetobacter baumannii is challenging the healthcare community as the cause of a wide range of untreatable infections. New targets need to be explored for the development of therapeutics. The potassium-dependent protein (Kdp) system was investigated via bioinformatics and genetic tools. An isogenic mutant was constructed in kdpE and complemented in trans Gene expression and the ability to grow under potassium-limited conditions were investigated. Finally, the role of KdpE in virulence was examined in the murine pneumonia model. The A. baumannii Kdp system has a distinct arrangement and is well conserved among A. baumannii strains. The genes encoding the 5 members of the system are transcriptionally linked. kdpE is upregulated >70-fold under potassium-limited conditions. The ΔkdpE mutant showed a significant growth defect under potassium-limited conditions and in the colonization of mice lungs. These defects could be restored upon introducing kdpE on a multiple-copy plasmid. Proteomic analyses indicated that KdpE could be regulating several proteins with potential involvement in pathogenesis. For the first time, A. baumannii KdpE is shown to be crucial to pneumonia onset, and targeting this system can be a viable approach to treating these fatal infections. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.
-
Subramaniyan, Jayanthi Siva; Sundaram, Jeya Meenakshi
2018-01-01
ICU shows increasing incidence of infection associated with the use of invasive procedures for the diagnostic purpose as well as the indiscriminate use of antibiotics. Pseudomonas aeruginosa and Acinetobacter species are "very successful" pathogen and the emergence of the Metallo-β-Lactamases (MBL) is becoming a therapeutic challenge. To isolate the Nonfermenting Gram negative bacilli from the ICU samples. To identify the metallo betalactamase producers and to detect the bla gene presence among the Pseudomonas aeruginosa and Acinetobacter baumannii . The Nonfermenting Gram negative bacilli isolates from the ICU samples were taken over for 5 years (2009-2014) in a tertiary care hospital. The isolates of Pseudomonas species and Acinetobacter species were confirmed by API analyser and processed according to standard procedures. Detection of the MBL producers were done by E strip method and subjected for bla gene detection by PCR method. In our study a total of 195 isolates of NFGNB were obtained from various ICU. Of these MBL producers, 26 % were Pseudomonas aeruginosa and 25 % were Acinetobacter baumannii . The subtypes of bla VIM MBL producing P.aeruginosa were 26%. The predominant gene coding for MBL activity in A.baumannii were found to be bla OXA gene 11.9%. The gene accession numbers were KF975367, KF975372. We have to control the development and dissemination of these superbugs among the ICU's.
-
Muster, N; Derecho, I; Dallal, F; Alvarez, R; McCoy, K B; Mogul, R
2015-04-01
Herein, we report on the purification, characterization, and sequencing of catalase from Acinetobacter gyllenbergii 2P01AA, an extremely oxidation-resistant bacterium that was isolated from the Mars Phoenix spacecraft assembly facility. The Acinetobacter are dominant members of the microbial communities that inhabit spacecraft assembly facilities and consequently may serve as forward contaminants that could impact the integrity of future life-detection missions. Catalase was purified by using a 3-step chromatographic procedure, where mass spectrometry provided respective subunit and intact masses of 57.8 and 234.6 kDa, which were consistent with a small-subunit tetrameric catalase. Kinetics revealed an extreme pH stability with no loss in activity between pH 5 and 11.5 and provided respective kcat/Km and kcat values of ∼10(7) s(-1) M(-1) and 10(6) s(-1), which are among the highest reported for bacterial catalases. The amino acid sequence was deduced by in-depth peptide mapping, and structural homology suggested that the catalases from differing strains of A. gyllenbergii differ only at residues near the subunit interfaces, which may impact catalytic stability. Together, the kinetic, alkali-tolerant, and halotolerant properties of the catalase from A. gyllenbergii 2P01AA are significant, as they are consistent with molecular adaptations toward the alkaline, low-humidity, and potentially oxidizing conditions of spacecraft assembly facilities. Therefore, these results support the hypothesis that the selective pressures of the assembly facilities impact the microbial communities at the molecular level, which may have broad implications for future life-detection missions.
-
2010-04-01
the most active aminoglycoside (27.1% of isolates were susceptible ). Disk diffusion and Etest tended to be more accurate than the Vitek 2 , Phoenix...and MicroScan automated systems; but errors were noted with all methods. The Vitek 2 instrument incorrectly reported that more than one-third of the...Acinetobacter, we have observed in clinical practice at the San Antonio Mil- itary Medical Center results of susceptibility to amikacin from the Vitek 2
-
Minerdi, Daniela; Zgrablic, Ivan; Castrignanò, Silvia; Catucci, Gianluca; Medana, Claudio; Terlizzi, Maria Elena; Gribaudo, Giorgio; Gilardi, Gianfranco; Sadeghi, Sheila J
2016-01-01
Antimicrobial resistance is a global issue currently resulting in the deaths of hundreds of thousands of people a year worldwide. Data present in the literature illustrate the emergence of many bacterial species that display resistance to known antibiotics; Acinetobacter spp. are a good example of this. We report here that Acinetobacter radioresistens has a Baeyer-Villiger monooxygenase (Ar-BVMO) with 100% amino acid sequence identity to the ethionamide monooxygenase of multidrug-resistant (MDR) Acinetobacter baumannii. Both enzymes are only distantly phylogenetically related to other canonical bacterial BVMO proteins. Ar-BVMO not only is capable of oxidizing two anticancer drugs metabolized by human FMO3, danusertib and tozasertib, but also can oxidize other synthetic drugs, such as imipenem. The latter is a member of the carbapenems, a clinically important antibiotic family used in the treatment of MDR bacterial infections. Susceptibility tests performed by the Kirby-Bauer disk diffusion method demonstrate that imipenem-sensitive Escherichia coli BL21 cells overexpressing Ar-BVMO become resistant to this antibiotic. An agar disk diffusion assay proved that when imipenem reacts with Ar-BVMO, it loses its antibiotic property. Moreover, an NADPH consumption assay with the purified Ar-BVMO demonstrates that this antibiotic is indeed a substrate, and its product is identified by liquid chromatography-mass spectrometry to be a Baeyer-Villiger (BV) oxidation product of the carbonyl moiety of the β-lactam ring. This is the first report of an antibiotic-inactivating BVMO enzyme that, while mediating its usual BV oxidation, also operates by an unprecedented mechanism of carbapenem resistance. Copyright © 2015, American Society for Microbiology. All Rights Reserved.
-
2006-11-01
EFFECTIVENESS OF HALOGEN-BASED DISINFECTANTS AGAINST Acinetobacter baumannii: WOUND CARE AND ENVIROMENTAL DECONTAMINATION James...a standard E. coli comparator, in a novel bacterial culture system that incorporated a three log range of organic growth media concentrations. We...report the highest dilutions of stock disinfectant able to inhibit replication or kill the bacteria , denoted as the maximum inhibitory dilution
-
Majewski, Piotr; Wieczorek, Piotr; Ojdana, Dominika; Sacha, Paweł Tomasz; Wieczorek, Anna; Tryniszewska, Elżbieta Anna
2014-04-01
The growing incidence of multidrug resistance (MDR) in bacteria is an emerging challenge in the treatment of infections. Acinetobacter baumannii is an opportunistic pathogen prone to exhibit MDR that contributes significantly to nosocomial infections, particularly in severely ill patients. Thus, we performed research on rifampicin activity against selected MDR OXA-72 carbapenemase-producing A. baumannii strains. Since it is widely accepted that rifampicin should not be used as monotherapy in order to avoid the rapid development of rifampicin resistance, we evaluated the efficacy of combination therapy with imipenem. Minimal inhibitory concentrations (MICs) of both rifampicin and imipenem were determined by use of the broth microdilution method. Evaluations of the interactions between rifampicin and imipenem were performed by analysis of the fractional inhibitory concentration index (∑FIC), determined using the checkerboard titration method. All tested isolates showed full susceptibility to rifampicin. The checkerboard method revealed synergism in 5 isolates (29%) and an additive effect in another 5 isolates (29%); no difference was reported in the remaining 7 isolates (41%). Strains moderately resistant to imipenem (MIC ≤ 64 mg/l) tended to show synergy or additive interaction. We conclude that in vitro synergism or an additive interaction between rifampicin and imipenem most likely occurs in A. baumannii strains showing moderate resistance to imipenem (MIC ≤ 64 mg/l). Moreover, utilizing this combination in the therapy of infections caused by strains exhibiting higher levels of resistance (MIC > 64 mg/l) is not recommended since in this setting imipenem could not prevent the development of rifampicin resistance.
-
Rock, Clare; Harris, Anthony D; Johnson, J Kristie; Bischoff, Werner E; Thom, Kerri A
2015-07-01
Using a validated air sampling method we found Acinetobacter baumannii in the air surrounding only 1 of 12 patients known to be colonized or infected with A. baumannii. Patients' closed-circuit ventilator status, frequent air exchanges in patient rooms, and short sampling time may have contributed to this low burden.
-
Evans, Scott R; Hujer, Andrea M; Jiang, Hongyu; Hill, Carol B; Hujer, Kristine M; Mediavilla, Jose R; Manca, Claudia; Tran, Thuy Tien T; Domitrovic, T Nicholas; Higgins, Paul G; Seifert, Harald; Kreiswirth, Barry N; Patel, Robin; Jacobs, Michael R; Chen, Liang; Sampath, Rangarajan; Hall, Thomas; Marzan, Christine; Fowler, Vance G; Chambers, Henry F; Bonomo, Robert A
2017-01-01
The widespread dissemination of carbapenem-resistant Acinetobacter spp. has created significant therapeutic challenges. At present, rapid molecular diagnostics (RMDs) that can identify this phenotype are not commercially available. Two RMD platforms, PCR combined with electrospray ionization mass spectrometry (PCR/ESI-MS) and molecular beacons (MB), for detecting genes conferring resistance/susceptibility to carbapenems in Acinetobacter spp. were evaluated. An archived collection of 200 clinical Acinetobacter sp. isolates was tested. Predictive values for susceptibility and resistance were estimated as a function of susceptibility prevalence and were based on the absence or presence of beta-lactamase (bla) NDM, VIM, IMP, KPC, and OXA carbapenemase genes (e.g., bla OXA-23 , bla OXA-24/40 , and bla OXA-58 found in this study) against the reference standard of MIC determinations. According to the interpretation of MICs, 49% (n = 98) of the isolates were carbapenem resistant (as defined by either resistance or intermediate resistance to imipenem). The susceptibility sensitivities (95% confidence interval [CI]) for imipenem were 82% (74%, 89%) and 92% (85%, 97%) for PCR/ESI-MS and MB, respectively. Resistance sensitivities (95% CI) for imipenem were 95% (88%, 98%) and 88% (80%, 94%) for PCR/ESI-MS and MB, respectively. PRIMERS III establishes that RMDs can discriminate between carbapenem resistance and susceptibility in Acinetobacter spp. In the context of a known prevalence of resistance, SPVs and RPVs can inform clinicians regarding the best choice for empiric antimicrobial therapy against this multidrug-resistant pathogen. Copyright © 2016 American Society for Microbiology.
-
Subramaniyan, Jayanthi Siva; Sundaram, Jeya Meenakshi
2018-01-01
CONTEXT: ICU shows increasing incidence of infection associated with the use of invasive procedures for the diagnostic purpose as well as the indiscriminate use of antibiotics. Pseudomonas aeruginosa and Acinetobacter species are “very successful” pathogen and the emergence of the Metallo-β-Lactamases (MBL) is becoming a therapeutic challenge. AIMS: To isolate the Nonfermenting Gram negative bacilli from the ICU samples. To identify the metallo betalactamase producers and to detect the bla gene presence among the Pseudomonas aeruginosa and Acinetobacter baumannii. SETTINGS AND DESIGN: The Nonfermenting Gram negative bacilli isolates from the ICU samples were taken over for 5 years (2009-2014) in a tertiary care hospital. METHODS AND MATERIALS: The isolates of Pseudomonas species and Acinetobacter species were confirmed by API analyser and processed according to standard procedures. Detection of the MBL producers were done by E strip method and subjected for bla gene detection by PCR method. RESULTS: In our study a total of 195 isolates of NFGNB were obtained from various ICU. Of these MBL producers, 26 % were Pseudomonas aeruginosa and 25 % were Acinetobacter baumannii. The subtypes of blaVIM MBL producing P.aeruginosa were 26%. The predominant gene coding for MBL activity in A.baumannii were found to be blaOXA gene 11.9%. The gene accession numbers were KF975367, KF975372. CONCLUSIONS: We have to control the development and dissemination of these superbugs among the ICU's. PMID:29692589
-
Yang, Qiu; Rui, Yongyu
2016-01-01
Nosocomial infections caused by Acinetobacter spp. resistant to carbapenems are increasingly reported worldwide. Carbapenem-resistant Acinetobacter (CRA) is becoming a serious concern with increasing patient morbidity, mortality, and lengths of hospital stay. Therefore, the rapid detection of CRA is essential for epidemiological surveillance. Polymerase chain reaction (PCR) has been extensively used for the rapid identification of most pathogens. In this study, we have developed two multiplex real-time PCR assays to detect and differentiate A. baumannii and non-A. baumannii Acinetobacter spp, and common carbapenemase genes, including blaNDM, blaOXA-23-like, blaOXA-40-like, blaOXA-51-like, and blaOXA-58-like. We demonstrate the potential utility of these assays for the direct detection of blaNDM-, blaOXA-23-like-, blaOXA-40-like-, blaOXA-51-like-, and blaOXA-58-like-positive CRA in clinical specimens. Primers were specifically designed, and two multiplex real-time PCR assays were developed: multiplex real-time PCR assay1 for the detection of Acinetobacter baumannii 16S–23S rRNA internal transcribed spacer sequence, the Acinetobacter recA gene, and class-B-metalloenzyme-encoding gene blaNDM; and multiplex real-time PCR assay2 to detect class-D-oxacillinase-encoding genes (blaOXA-23-like, blaOXA-40-like, blaOXA-51-like,and blaOXA-58-like). The assays were performed on an ABI Prism 7500 FAST Real-Time PCR System. CRA isolates were used to compare the assays with conventional PCR and sequencing. Known amounts of CRA cells were added to sputum and fecal specimens and used to test the multiplex real-time PCR assays. The results for target and nontarget amplification showed that the multiplex real-time PCR assays were specific, the limit of detection for each target was 10 copies per 20 μL reaction volume, the assays were linear over six log dilutions of the target genes (r2 > 0.99), and the Ct values of the coefficients of variation for intra- and interassay
-
Yang, Ming-Yeh; Chang, Kai-Chih; Chen, Liang-Yu; Wang, Po-Ching; Chou, Chih-Chiang; Wu, Zhong-Bin; Hu, Anren
2018-03-01
Photodynamic inactivation (PDI) is a non-invasive and safe therapeutic method for microbial infections. Bacterial antibiotic resistance is caused by antibiotics abuse. Drug-resistant Acinetobacter spp. is a serious problem in hospitals around the world. These pathogens from nosocomial infections have high mortality rates in frailer people, and Acinetobacter spp. is commonly found in immunocompromised patients. Visible light is safer than ultraviolet light (UV) for PDI of nosocomial pathogens with mammalian cells. Zinc oxide nanoparticles (ZnO-NPs) were used in this study as an antimicrobial agent and a photosensitizer. ZnO is recognized as safe and has extensive usage in food additives, medical and cosmetic products. In this study, we used 0.125 mg/ml ZnO-NPs combined with 10.8 J/cm 2 blue light (BL) on Acinetobacter baumannii (A. baumannii) that could significantly reduce microbial survival. However, individual exposure to ZnO-NPs does not affect the viability of A. baumannii. BL irradiation could trigger the antimicrobial ability of ZnO nanoparticles on A. baumannii. The mechanism of photocatalytic ZnO-NPs treatment for sterilization occurs through bacterial membrane disruptions. Otherwise, the photocatalytic ZnO-NPs treatment showed high microbial eradication in nosocomial pathogens, including colistin-resistant and imipenem-resistant A. baumannii and Klebsiella pneumoniae. Based on our results, the photocatalytic ZnO-NPs treatment could support hygiene control and clinical therapies without antibiotics to nosocomial bacterial infections. Copyright © 2018. Published by Elsevier B.V.
-
Domingues, Sara; Rosário, Natasha; Ben Cheikh, Hadhemi; Da Silva, Gabriela Jorge
2018-05-15
Acinetobacter baumannii has intrinsic beta-lactamase genes, namely ampC and bla OXA-51 -like, which are only strongly expressed when the ISAba1 insertion sequence is upstream the 5' end of the genes. A second ampC gene has also been identified in some clinical A. baumannii strains. The increased expression of these genes leads to resistance to beta-lactams, including third-generation cephalosporins and/or carbapenems. The aim of this work was to assess the involvement of natural transformation in the transfer of chromosomal ampC-associated mobile elements, and related changes in the resistance profile of recipient cells. Natural transformation assays with the naturally competent A. baumannii A118 clinical isolate as recipient cell and the multidrug resistant A. baumannii Ab51 clinical isolate as the source of donor DNA produced transformants. All tested transformants showed integration of the ISAba1 close to the ampC gene. In two transformants, the ISAba1 was acquired by transposition and inserted between the usual folE and the ampC genes. The remaining transformants acquired the ISAba1 adjacent to a second ampC gene, as part of Tn6168, likely by homologous recombination. Our study demonstrates that natural transformation can contribute to the widespread of beta-lactams resistance, and acquisition of non-resistant determinants can lead to changes in the susceptibility profile of A. baumannii strains. Copyright © 2018 Elsevier B.V. All rights reserved.
-
Purification and characterization of chondroitinase ABC from Acinetobacter sp. C26.
Zhu, Changliang; Zhang, Jingliang; Zhang, Jing; Jiang, Yanhui; Shen, Zhaopeng; Guan, Huashi; Jiang, Xiaolu
2017-02-01
An extracellular chondroitinase ABC (ChSase ABC, EC 4.2.2.4) produced by cultivating Acinetobacter sp. C26, was purified to homogeneity from the supernatant by ammonium sulfate fractionation, Q-Sepharose Fast Flow and Sephadex G-100 chromatography. The 76kDa enzyme was purified 48.09-fold to homogeneity with specific activity of 348.64U/mg, Using the chondroitin sulfate A (CS-A) as substrate, the maximal reaction rate (Vmax) and Michaelis-Menten constant (Km) of ChSase ABC were found to be 10.471μmol/min/ml and 0.105mg/ml, respectively. The enzyme showed the highest activity at the optimal conditions of pH 6.0 and 42 ∘C, respectively. This enzyme was stable at pH 5-10, 5-9 and 5-7 at 4°C, 37°C and 42°C, respectively. Investigation about thermal stability of ChSase ABC displayed that it was stable at 37°C. ChSase ABC activity was increased in presence of Na + , K + , Mn 2+ , 1,10-phenanthrolin and strongly inhibited by Cu 2+ , Hg 2+ , Al 3+ and SDS. These properties suggested that ChSase ABC from Acinetobacter sp. C26 bring promising prospects in medical and industry applications. Copyright © 2016 Elsevier B.V. All rights reserved.
-
Class 2 Integrons Dissemination Among Multidrug Resistance (MDR) Clones of Acinetobacter baumannii
Ramírez, María Soledad; Morales, Amanda; Vilacoba, Elisabet; Márquez, Carolina
2014-01-01
Acinetobacter baumannii has emerged as a serious problem in the hospital environment at a global scale. Previous results from our laboratory showed a high frequency of class 2 integrons in A. baumannii strains from Argentina regarding the low rate of this element in A. baumannii isolates from the rest of the world. To reveal the current epidemiology of class 2 integrons, a molecular surveillance analyzing 78 multidrug resistant (MDR) A. baumannii isolates from Argentina and Uruguay was performed, exposing the presence of class 2 integron in the 36.61% of the isolates. Class 2 integron characterization showed that the typical Tn7::In2-7 array was present in 26 out of 27 intI2 positive isolates. All intI2 positive isolates contained at least one of the Tn7 transposition genes. In addition, we identified that 18 intI2 positive isolates possessed the Tn7::In2-7 within the attTn7 site. The molecular typing evidenced that clones I and IV that do not belong to widespread European clones I and II were found among the intI2 positive isolates. Our results exposed the widely dissemination of class 2 integron among MDR A. baumannii isolates from Argentina and Uruguay, also showing the persistence of two novel clones in our region, which could explain in part the high frequency of class 2 integron found in our region. PMID:22198473
-
Piran, Arezoo; Shahcheraghi, Fereshteh; Solgi, Hamid; Rohani, Mahdi; Badmasti, Farzad
2017-10-01
The multi-drug resistant (MDR) Acinetobacter baumannii as an important nosocomial pathogen has emerged a global health concern in recent years. In this study, we applied three easier, faster, and cost-effective methods including PCR-based open reading frames (ORFs) typing, sequence typing of bla OXA-51-like and RAPD-PCR method to rapid typing of A. baumannii strains. Taken together in the present study the results of ORFs typing, PCR-sequencing of bla OXA-51-like genes and MLST sequence typing revealed there was a high prevalence (62%, 35/57) of ST2 as international and successful clone which detected among clinical isolates of multi-drug resistant A. baumannii with ORF pattern B and bla OXA-66 gene. Only 7% (4/57) of MDR isolates belonged to ST1 with ORF pattern A and bla OXA-69 gene. Interestingly, we detected singleton ST513 (32%, 18/57) that encoded bla OXA-90 and showed the ORF pattern H as previously isolated in Middle East. Moreover, our data showed RAPD-PCR method can detect divergent strains of the STs. The Cl-1, Cl-2, Cl-3, Cl-4, Cl-10, Cl-11, Cl-12, Cl-13 and Cl-14 belonged to ST2. While the Cl-6, Cl-7, Cl-8 and Cl-9 belonged to ST513. Only Cl-5 belonged to ST1. It seems that the combination of these methods have more discriminatory than any method separately and could be effectively applied to rapid detection of the clonal complex (CC) of A. baumannii strains without performing of MLST or PFGE. Copyright © 2017 Elsevier B.V. All rights reserved.
-
Davoodi, Saba; Boroumand, Mohammad Ali; Sepehriseresht, Saeed; Pourgholi, Leila
2015-01-01
Background Acinetobacter baumannii, is an opportunistic pathogen and is responsible for numerous nosocomial infections. In recent years, this microorganism has been resistant to a wide range of antibiotics. One of the most important mechanisms of resistance in this microorganism is production of metallo-beta-lactamases (MBLs). Objectives The aim of this study was to detect VIM- and IMP-type metallo-beta-lactamase genes in Acinetobacter baumanniiisolates from patients in two Hospitals in Tehran. Materials and Methods 104 isolates were tested using the PCR method for the identification of VIM- and IMP-type genes. Results vim1, vim2, imp1 and imp2 genes were detected in 6.7%, 41.7%, 50% and 1.7% of the isolates from Tehran Heart Center, and in 29.5%, 38.6%, 4.5% and 4.5% of the isolates from Shahid Mutahhari Hospital respectively. Discussions Our analysis revealed that the majority of the isolates had at least one of these genes, indicating that MBLs production is an important resistance mechanism in Acinetobacter baumannii. PMID:28959283
-
An update on the arsenal for multidrug-resistant Acinetobacter infections: polymyxin antibiotics.
Kassamali, Zahra; Jain, Rupali; Danziger, Larry H
2015-01-01
To review recent clinical pharmacokinetic and pharmacodynamic data to optimize dosing regimens for polymyxin B and colistin for treatment of infections due to A. baumannii. A literature search was performed using the search terms Acinetobacter, polymyxin, colistin, polymyxin B on MEDLINE. Additional references were identified from the resulting citations. Increasing the dose of polymyxin B or colistin and using either in combination with other antibiotic agents demonstrates improved antimicrobial activity against Acinetobacter spp. Polymyxin B, unlike colistin, is available as an active drug and appears to be relatively unaffected by renal function. This is advantageous both for patients with renal impairment and for those with intact renal function. Achieving therapeutic serum concentrations of colistin may be difficult for those with intact renal function due to rapid clearance of the prodrug, colistimethate sodium (CMS). Clinical data are still lacking for polymyxin B, and it remains to be seen whether advantages demonstrated in PK/PD analyses will persist in the larger scale of patient care and safety. The use of higher doses of either colistin or polymyxin B, as well as combination with other antibiotics, may prevent emerging resistance and preserve the activity of polymyxins against A. baumannii. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.
-
Siroy, Axel; Molle, Virginie; Lemaître-Guillier, Christelle; Vallenet, David; Pestel-Caron, Martine; Cozzone, Alain J.; Jouenne, Thierry; Dé, Emmanuelle
2005-01-01
It has been recently shown that resistance to both imipenem and meropenem in multidrug-resistant clinical strains of Acinetobacter baumannii is associated with the loss of a heat-modifiable 25/29-kDa outer membrane protein, called CarO. This study aimed to investigate the channel-forming properties of CarO. Mass spectrometry analyses of this protein band detected another 25-kDa protein (called Omp25), together with CarO. Both proteins presented similar physicochemical parameters (Mw and pI). We overproduced and purified the two polypeptides as His-tagged recombinant proteins. Circular dichroism analyses demonstrated that the secondary structure of these proteins was mainly a β-strand conformation with spectra typical of porins. We studied the channel-forming properties of proteins by reconstitution into artificial lipid bilayers. In these conditions, CarO induced ion channels with a conductance value of 110 pS in 1 M KCl, whereas the Omp25 protein did not form any channels, despite its suggested porin function. The pores formed by CarO showed a slight cationic selectivity and no voltage closure. No specific imipenem binding site was found in CarO, and this protein would rather form unspecific monomeric channels. PMID:16304148
-
Fulsundar, Shweta; Kulkarni, Heramb M; Jagannadham, Medicharla V; Nair, Rashmi; Keerthi, Sravani; Sant, Pooja; Pardesi, Karishma; Bellare, Jayesh; Chopade, Balu Ananda
2015-01-01
Acinetobacter radioresistens is an important member of genus Acinetobacter from a clinical point of view. In the present study, we report that a clinical isolate of A. radioresistens releases outer membrane vesicles (OMVs) under in vitro growth conditions. OMVs were released in distinctive size ranges with diameters from 10 to 150 nm as measured by the dynamic light scattering (DLS) technique. Additionally, proteins associated with or present into OMVs were identified using LC-ESI-MS/MS. A total of 71 proteins derived from cytosolic, cell membrane, periplasmic space, outer membrane (OM), extracellular and undetermined locations were found in OMVs. The initial characterization of the OMV proteome revealed a correlation of some proteins to biofilm, quorum sensing, oxidative stress tolerance, and cytotoxicity functions. Thus, the OMVs of A. radioresistens are suggested to play a role in biofilm augmentation and virulence possibly by inducing apoptosis. Copyright © 2015 Elsevier Ltd. All rights reserved.
-
Acinetobacter baumannii Biofilm Formation in Human Serum and Disruption by Gallium
Runci, Federica; Bonchi, Carlo; Frangipani, Emanuela; Visaggio, Daniela
2016-01-01
ABSTRACT Biofilm-associated infections caused by Acinetobacter baumannii are extremely recalcitrant to antibiotic treatment. We report that A. baumannii develops a mature biofilm when grown in complement-free human serum (HS). We demonstrate that 16 μM gallium nitrate (GaN) drastically reduces A. baumannii growth and biofilm formation in HS, whereas 64 μM GaN causes massive disruption of preformed A. baumannii biofilm. These findings pave the way to the repurposing of GaN as an antibiofilm agent for A. baumannii. PMID:27799219
-
Saranathan, Rajagopalan; Vasanth, Vaidyanathan; Vasanth, Thamodharan; Shabareesh, Pidathala Raghavendra Venkata; Shashikala, P; Devi, Chandrakesan Sheela; Kalaivani, Ramakrishnan; Asir, Johny; Sudhakar, Pagal; Prashanth, K
2015-05-01
The molecular epidemiology and carbapenem resistance mechanisms of clinical isolates of Acinetobacter baumannii obtained from a south Indian tertiary care hospital were investigated by repetitive extragenic palindromic sequence PCR (REP-PCR) and multi-locus sequence typing (MLST). Analysis of resistant determinants was achieved by PCR screening for the presence of genes encoding OXA-carbapenemases, metallo-β-lactamases (MBLs) and efflux pumps. REP-PCR generated around eight clusters of high heterogeneity; of these, two major clusters (I and V) appeared to be clonal in origin. Analysis of representative isolates from different clusters by MLST revealed that most of the isolates belonged to sequence type 103 of CC103(B) . Second most prevalent ST belonged to clonal complex (CC) 92(B) which is also referred to as international clone II. Most of the isolates were multi-drug resistant, being susceptible only to polymyxin-B and newer quinolones. Class D β-lactamases such as blaOXA-51-like (100%), blaOXA-23-like (56.8%) and blaOXA-24-like (14.8%) were found to be predominant, followed by a class B β-lactamase, namely blaIMP-1 (40.7%); none of the isolates had blaOXA-58 like, blaNDM-1 or blaSIM-1 . Genes of efflux-pump adeABC were predominant, most of isolates being biofilm producers that were PCR-positive for autoinducer synthase gene (>94%). Carbapenem non-susceptible isolates were highly diverse and present throughout the hospital irrespective of type of ward or intensive care unit. Although previous reports have documented diverse resistant mechanisms in A. baumannii, production of MBL and OXA-type of carbapenamases were found to be the predominant mechanism(s) of carbapenem resistance identified in strains isolated from Southern India. © 2015 The Societies and Wiley Publishing Asia Pty Ltd.
-
Kothari, Ankita; Charrier, Marimikel; Wu, Yu -Wei; ...
2016-09-22
The hydrocarbonoclastic bacterium Acinetobacter venetianus RAG-1 has attracted substantial attention due to its powerful oil-degrading capabilities and its potential to play an important ecological role in the cleanup of alkanes. In this study, we compare the transcriptome of the strain RAG-1 grown in dodecane, the corresponding alkanol (dodecanol), and sodium acetate for the characterization of genes involved in dodecane uptake and utilization. Comparison of the transcriptional responses of RAG-1 grown on dodecane led to the identification of 1074 genes that were differentially expressed relative to sodium acetate. Of these, 622 genes were upregulated when grown in dodecane. The highly upregulatedmore » genes were involved in alkane catabolism, along with stress response. Our data suggest AlkMb to be primarily involved in dodecane oxidation. Transcriptional response of RAG-1 grown on dodecane relative to dodecanol also led to the identification of permease, outer membrane protein and thin fimbriae coding genes potentially involved in dodecane uptake. As a result, this study provides the first model for key genes involved in alkane uptake and metabolism in A. venetianus RAG-1.« less
-
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kothari, Ankita; Charrier, Marimikel; Wu, Yu -Wei
The hydrocarbonoclastic bacterium Acinetobacter venetianus RAG-1 has attracted substantial attention due to its powerful oil-degrading capabilities and its potential to play an important ecological role in the cleanup of alkanes. In this study, we compare the transcriptome of the strain RAG-1 grown in dodecane, the corresponding alkanol (dodecanol), and sodium acetate for the characterization of genes involved in dodecane uptake and utilization. Comparison of the transcriptional responses of RAG-1 grown on dodecane led to the identification of 1074 genes that were differentially expressed relative to sodium acetate. Of these, 622 genes were upregulated when grown in dodecane. The highly upregulatedmore » genes were involved in alkane catabolism, along with stress response. Our data suggest AlkMb to be primarily involved in dodecane oxidation. Transcriptional response of RAG-1 grown on dodecane relative to dodecanol also led to the identification of permease, outer membrane protein and thin fimbriae coding genes potentially involved in dodecane uptake. As a result, this study provides the first model for key genes involved in alkane uptake and metabolism in A. venetianus RAG-1.« less
-
Djordjevic, Z M; Folic, M M; Jankovic, S M
2017-10-01
Regular surveillance of antimicrobial resistance is an important component of multifaceted interventions directed at the problem with resistance of bacteria causing healthcare-associated infections (HAIs) in intensive care units (ICUs). Our aim was to analyse antimicrobial consumption and resistance among isolates of Pseudomonas aeruginosa and Acinetobacter spp. causing HAIs, before and after the introduction of mandatory reporting of resistance patterns to prescribers. A retrospective observational study was conducted between January 2011 and December 2015, at an interdisciplinary ICU of the Clinical Centre Kragujevac, Serbia. The intervention consisted of continuous resistance monitoring of all bacterial isolates from ICU patients and biannual reporting of results per isolate to prescribers across the hospital. Both utilization of antibiotics and density of resistant isolates of P. aeruginosa and Acinetobacter spp. were followed within the ICU. Resistance densities of P. aeruginosa to all tested antimicrobials were lower in 2015, in comparison with 2011. Although isolates of Acinetobacter spp. had lower resistance density in 2015 than in 2011 to the majority of investigated antibiotics, a statistically significant decrease was noted only for piperacillin/tazobactam. Statistically significant decreasing trends of consumption were recorded for third-generation cephalosporins, aminoglycosides and fluoroquinolones, whereas for the piperacillin/tazobactam, ampicillin/sulbactam and carbapenems, utilization trends were decreasing, but without statistical significance. In the same period, increasing trends of consumption were observed for tigecycline and colistin. Regular monitoring of resistance of bacterial isolates in ICUs and reporting of summary results to prescribers may lead to a significant decrease in utilization of some antibiotics and slow restoration of P. aeruginosa and Acinetobacter spp. susceptibility. © 2017 John Wiley & Sons Ltd.
-
2009-01-01
Background Increasing reports of carbapenem resistant Acinetobacter baumannii infections are of serious concern. Reliable susceptibility testing results remains a critical issue for the clinical outcome. Automated systems are increasingly used for species identification and susceptibility testing. This study was organized to evaluate the accuracies of three widely used automated susceptibility testing methods for testing the imipenem susceptibilities of A. baumannii isolates, by comparing to the validated test methods. Methods Selected 112 clinical isolates of A. baumanii collected between January 2003 and May 2006 were tested to confirm imipenem susceptibility results. Strains were tested against imipenem by the reference broth microdilution (BMD), disk diffusion (DD), Etest, BD Phoenix, MicroScan WalkAway and Vitek 2 automated systems. Data were analysed by comparing the results from each test method to those produced by the reference BMD test. Results MicroScan performed true identification of all A. baumannii strains while Vitek 2 unidentified one strain, Phoenix unidentified two strains and misidentified two strains. Eighty seven of the strains (78%) were resistant to imipenem by BMD. Etest, Vitek 2 and BD Phoenix produced acceptable error rates when tested against imipenem. Etest showed the best performance with only two minor errors (1.8%). Vitek 2 produced eight minor errors(7.2%). BD Phoenix produced three major errors (2.8%). DD produced two very major errors (1.8%) (slightly higher (0.3%) than the acceptable limit) and three major errors (2.7%). MicroScan showed the worst performance in susceptibility testing with unacceptable error rates; 28 very major (25%) and 50 minor errors (44.6%). Conclusion Reporting errors for A. baumannii against imipenem do exist in susceptibility testing systems. We suggest clinical laboratories using MicroScan system for routine use should consider using a second, independent antimicrobial susceptibility testing method to
-
Acinetobacter baumannii Biofilm Formation in Human Serum and Disruption by Gallium.
Runci, Federica; Bonchi, Carlo; Frangipani, Emanuela; Visaggio, Daniela; Visca, Paolo
2017-01-01
Biofilm-associated infections caused by Acinetobacter baumannii are extremely recalcitrant to antibiotic treatment. We report that A. baumannii develops a mature biofilm when grown in complement-free human serum (HS). We demonstrate that 16 μM gallium nitrate (GaN) drastically reduces A. baumannii growth and biofilm formation in HS, whereas 64 μM GaN causes massive disruption of preformed A. baumannii biofilm. These findings pave the way to the repurposing of GaN as an antibiofilm agent for A. baumannii. Copyright © 2016 American Society for Microbiology.
-
Martins, Andreza F; Kuchenbecker, Ricardo S; Pilger, Kátia O; Pagano, Mariana; Barth, Afonso L
2012-03-01
Most published data on multidrug-resistant Acinetobacter baumanii (MDR Ab) are derived from outbreaks. We report incidence trends on health care-acquired infections due to MDR Ab over a 12-month period in the city of Porto Alegre in southern Brazil. Clinical and epidemiologic data were obtained from the local health care information system of the municipal health department. Polymerase chain reaction was used to detect the presence of the genes bla(OXA-23-like), bla(OXA-24-like), bla(OXA-51), and bla(OXA-58), and repetitive sequence-based polymerase chain reaction and pulsed-field gel electrophoresis were performed for molecular typing. The highest rate of infection (9.0/1,000 inpatient-days) was identified in a trauma hospital. The gene bla(OXA-23-like) was identified in 99.0% of MDR Ab isolates. Eight main clonal groups were identified by molecular typing, and 3 of these were found in all hospitals. The presence of 3 clones in all hospitals demonstrates the ability of MDR Ab to spread among hospitals. Moreover, the occurrence of one particular clone (clone 4) throughout the study period suggests its increased ability to cause outbreaks and to remain in the environment. The monitoring of epidemic strains by molecular methods is of paramount importance to prevent or reduce the spread of MDR Ab. Copyright © 2012 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.
-
Effects of biochars and MWNTs on biodegradation behavior of atrazine by Acinetobacter lwoffii DNS32.
Yang, Fan; Jiang, Qun; Zhu, Moran; Zhao, Lulu; Zhang, Ying
2017-01-15
Whether the biodegradation of atrazine by Acinetobacter lwoffii DNS32 can have a difference in the presence of two representative carbon materials (CMs), namely, biochars (BCs) and carbon nanotubes (CNTs) is explored, through investigating the influence of CMs on the biodegradation rate, the viability of bacteria and the expression of atrazine genes in aqueous medium. Multi-walled carbon nanotubes (MWNTs), biochars resulted from corn straws (C-BCs) and that made from banana peels (B-BCs) were chosen as the examples. Compared to the control in the absence of C-BCs, B-BCs and MWNTs, the biodegradation efficiencies decrease from 95.3%, 101.8% and 94.8% to 82.6%, 41.8% and 31.1% as the concentrations of these materials increase from 10 to 100mg/L, indicating that BCs have relatively lower toxicity on the biodegradation of atrazine than CNTs, which are agreement with the results of bacterial viability. Transmission electron microscope (TEM) images of Acinetobacter lwoffii DNS32 cells exposure to CMs at 50mg/L show that the cell membrane can be destroyed at different levels after being exposed to various CMs, suggesting that the damage to the cell membrane induced by CMs is a substantial factor leading to the inactivation of bacteria, further decreasing the degradation rate and efficiency of bacteria. The enhanced bacterial growth and the up-regulation of degradation genes can stimulate the degradation rate to pre-adsorbed atrazine on the CMs. This study suggests that biodegradation of atrazine associated with CMs may depend on the carbon composition, structure and CM concentrations. The innovation point of this report is to compare the effects of biochars and CNTs on the degradation rate and activity of Acinetobacter lwoffii DNS32 and may help to further understand the environment effects of CMs. Copyright © 2016 Elsevier B.V. All rights reserved.
-
Orsinger-Jacobsen, Samantha J; Patel, Shenan S; Vellozzi, Ernestine M; Gialanella, Phillip; Nimrichter, Leonardo; Miranda, Kildare; Martinez, Luis R
2013-12-01
Acinetobacter baumannii is a frequent cause of hospital-acquired pneumonia, and has recently increased in incidence as the causative agent of severe disease in troops wounded in Afghanistan and Iraq. Clinical approaches are limited since A. baumannii strains isolated from patients are extremely resistant to current antimicrobials. A. baumannii can survive desiccation and during outbreaks has been recovered from various sites in the patients' environment. To better understand its prevalence in hospital settings, we used a stainless steel washer (SSW) platform to investigate A. baumannii biofilm formation on abiotic surfaces. Scanning electron microscopy demonstrated that A. baumannii forms strong biofilms on stainless steel surfaces. This platform was combined with a colorimetric 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide (XTT) reduction assay to observe the metabolic activity of bacterial cells, and to facilitate the manipulation and comparison of multiple A. baumannii clinical strains. A strong correlation between XTT and c.f.u. assays was demonstrated. To complement the cell viability assays, A. baumannii biofilm mass was measured by crystal violet staining. Furthermore, the effect of commonly used disinfectants and environmental stressors on A. baumannii biofilms and planktonic cells was compared and characterized. Biofilms on SSWs were significantly more resistant than their planktonic counterparts, providing additional evidence that may allow us to understand the high prevalence of this microbe in hospital settings. Our results validate that SSWs are a simple, versatile and innovative method to study A. baumannii biofilms in vitro.
-
Orsinger-Jacobsen, Samantha J.; Patel, Shenan S.; Vellozzi, Ernestine M.; Gialanella, Phillip; Nimrichter, Leonardo; Miranda, Kildare
2013-01-01
Acinetobacter baumannii is a frequent cause of hospital-acquired pneumonia, and has recently increased in incidence as the causative agent of severe disease in troops wounded in Afghanistan and Iraq. Clinical approaches are limited since A. baumannii strains isolated from patients are extremely resistant to current antimicrobials. A. baumannii can survive desiccation and during outbreaks has been recovered from various sites in the patients’ environment. To better understand its prevalence in hospital settings, we used a stainless steel washer (SSW) platform to investigate A. baumannii biofilm formation on abiotic surfaces. Scanning electron microscopy demonstrated that A. baumannii forms strong biofilms on stainless steel surfaces. This platform was combined with a colorimetric 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide (XTT) reduction assay to observe the metabolic activity of bacterial cells, and to facilitate the manipulation and comparison of multiple A. baumannii clinical strains. A strong correlation between XTT and c.f.u. assays was demonstrated. To complement the cell viability assays, A. baumannii biofilm mass was measured by crystal violet staining. Furthermore, the effect of commonly used disinfectants and environmental stressors on A. baumannii biofilms and planktonic cells was compared and characterized. Biofilms on SSWs were significantly more resistant than their planktonic counterparts, providing additional evidence that may allow us to understand the high prevalence of this microbe in hospital settings. Our results validate that SSWs are a simple, versatile and innovative method to study A. baumannii biofilms in vitro. PMID:24025603
-
Nomanpour, B; Ghodousi, A; Babaei, A; Abtahi, HR; Tabrizi, M; Feizabadi, MM
2011-01-01
Background and Objectives Pneumonia with Acinetobacter baumannii has a major therapeutic problem in health care settings. Decision to initiate correct antibiotic therapy requires rapid identification and quantification of organism. The aim of this study was to develop a rapid and sensitive method for direct detection of A. baumannii from respiratory specimens. Materials and Methods A Taqman real time PCR based on the sequence of bla oxa-51 was designed and used for direct detection of A. baumannii from 361 respiratory specimens of patients with pneumonia. All specimens were checked by conventional bacteriology in parallel. Results The new real time PCR could detect less than 200 cfu per ml of bacteria in specimens. There was agreement between the results of real time PCR and culture (Kappa value 1.0, p value<0.001). The sensitivity, specificity and predictive values of real time PCR were 100%. The prevalence of A. baumannii in pneumonia patients was 10.53 % (n=38). Poly-microbial infections were detected in 65.71% of specimens. Conclusion Acinetobacter baumannii is the third causative agent in nosocomial pneumonia after Pseudomonas aeroginosa (16%) and Staphylococcus aureus (13%) at Tehran hospitals. We recommend that 104 CFU be the threshold for definition of infection with A. baumannii using real time PCR. PMID:22530083
-
Simple Method for Markerless Gene Deletion in Multidrug-Resistant Acinetobacter baumannii
Oh, Man Hwan; Lee, Je Chul; Kim, Jungmin
2015-01-01
The traditional markerless gene deletion technique based on overlap extension PCR has been used for generating gene deletions in multidrug-resistant Acinetobacter baumannii. However, the method is time-consuming because it requires restriction digestion of the PCR products in DNA cloning and the construction of new vectors containing a suitable antibiotic resistance cassette for the selection of A. baumannii merodiploids. Moreover, the availability of restriction sites and the selection of recombinant bacteria harboring the desired chimeric plasmid are limited, making the construction of a chimeric plasmid more difficult. We describe a rapid and easy cloning method for markerless gene deletion in A. baumannii, which has no limitation in the availability of restriction sites and allows for easy selection of the clones carrying the desired chimeric plasmid. Notably, it is not necessary to construct new vectors in our method. This method utilizes direct cloning of blunt-end DNA fragments, in which upstream and downstream regions of the target gene are fused with an antibiotic resistance cassette via overlap extension PCR and are inserted into a blunt-end suicide vector developed for blunt-end cloning. Importantly, the antibiotic resistance cassette is placed outside the downstream region in order to enable easy selection of the recombinants carrying the desired plasmid, to eliminate the antibiotic resistance cassette via homologous recombination, and to avoid the necessity of constructing new vectors. This strategy was successfully applied to functional analysis of the genes associated with iron acquisition by A. baumannii ATCC 19606 and to ompA gene deletion in other A. baumannii strains. Consequently, the proposed method is invaluable for markerless gene deletion in multidrug-resistant A. baumannii. PMID:25746991
-
Characterization of Two Novel Propachlor Degradation Pathways in Two Species of Soil Bacteria
Martin, Margarita; Mengs, Gerardo; Allende, Jose Luis; Fernandez, Javier; Alonso, Ramon; Ferrer, Estrella
1999-01-01
Propachlor (2-chloro-N-isopropylacetanilide) is an acetamide herbicide used in preemergence. In this study, we isolated and characterized a soil bacterium, Acinetobacter strain BEM2, that was able to utilize this herbicide as the sole and limiting carbon source. Identification of the intermediates of propachlor degradation by this strain and characterization of new metabolites in the degradation of propachlor by a previously reported strain of Pseudomonas (PEM1) support two different propachlor degradation pathways. Washed-cell suspensions of strain PEM1 with propachlor accumulated N-isopropylacetanilide, acetanilide, acetamide, and catechol. Pseudomonas strain PEM1 grew on propachlor with a generation time of 3.4 h and a Ks of 0.17 ± 0.04 mM. Acinetobacter strain BEM2 grew on propachlor with a generation time of 3.1 h and a Ks of 0.3 ± 0.07 mM. Incubations with strain BEM2 resulted in accumulation of N-isopropylacetanilide, N-isopropylaniline, isopropylamine, and catechol. Both degradative pathways were inducible, and the principal product of the carbon atoms in the propachlor ring was carbon dioxide. These results and biodegradation experiments with the identified metabolites indicate that metabolism of propachlor by Pseudomonas sp. strain PEM1 proceeds through a different pathway from metabolism by Acinetobacter sp. strain BEM2. PMID:9925619
-
2017-06-01
exposures, Defense Manpower Data Center (DMDC) rosters to determine burden among Department of Defense (DOD) active duty (AD) service members, and the...above weighted historic IRs with the exception of the Marine Corps and Department of Defense (DOD) active duty (AD) populations. All current rates... Active Duty 119 8.7 Family Members 218 4.0 Retired 80 3.7 Othera 84 -- Gender Age Group (in Years) Beneficiary Type 4 Acinetobacter in the
-
Tiwari, Vishvanath; Nagpal, Isha; Subbarao, Naidu; Moganty, Rajeswari R
2012-07-01
Acinetobacter baumannii, one of the major Gram negative bacteria, causes nosocomial infections such as pneumonia, urinary tract infection, meningitis, etc. β-lactam-based antibiotics like penicillin are used conventionally to treat infections of A. baumannii; however, they are becoming progressively less effective as the bacterium produces diverse types of β-lactamases to inactivate the antibiotics. We have recently identified a novel β-lactamase, OXA-51 from clinical strains of A. baumannii from our hospital. In the present study, we generated the structure of OXA-51 using MODELLER9v7 and studied the interaction of OXA-51 with a number of β-lactams (penicillin, oxacillin, ceftazidime, aztreonam and imipenem) using two independent programs: GLIDE and GOLD. Based on the results of different binding parameters and number of hydrogen bonds, interaction of OXA-51 was found to be maximum with ceftazidime and lowest with imipenem. Further, molecular dynamics simulation results also support this fact. The lowest binding affinity of imipenem to OXA-51 indicates clearly that it is not efficiently cleaved by OXA-51, thus explaining its high potency against resistant A. baumannii. This finding is supported by experimental results from minimum inhibitory concentration analysis and transmission electron microscopy. It can be concluded that carbapenems (imipenem) are presently effective β-lactam antibiotics against resistant strains of A. baumannii harbouring OXA-51. The results presented here could be useful in designing more effective derivatives of carbapenem.
-
DOE Office of Scientific and Technical Information (OSTI.GOV)
Dickson, J.S.; Maxcy, R.B.
Inhibitory effects of radiolytic products were studied using Escherichia coli, Pediococcus cerevisiae, and two radiation-resistant microorganisms, an isolate of Moraxella-Acinetobacter and a Micrococcus sp. End Products of an irradiation dose of 300 Krads completely inhibited resistant organisms on an experimental medium with a very low concentration of nutrients. Plate count agar, with higher nutrient concentration, required 600 Krads to produce the same inhibition. On the same medium, radiation-sensitive organisms could tolerate products generated by a 1000 Krad dose. However, no inhibition could be detected when either Escherichia coli or Moraxella-Acinetobacter was incubated at 5/sup 0/C on the surface of freshmore » meat irradiated to 1500 Krad. The effects of inhibitory products in culture media could be mitigated by the addition of catalase or sodium pyruvate. 19 references, 2 figures, 4 tables.« less
-
Larcher, Romaric; Pantel, Alix; Arnaud, Erik; Sotto, Albert; Lavigne, Jean-Philippe
2017-07-06
Acinetobacter pittii is a nosocomial pathogen rarely involved in community-acquired infections. We report for the first time that A. pittii can be responsible for cavitary community-acquired pneumonia and study its virulence, and discuss its pathogenesis and treatment options. A 45-year-old woman with a history of smoking and systemic lupus was admitted to Nimes University Hospital (France) with coughing and sputum lasting for three weeks. Thoracic CT scanner showed cavitary pneumonia. Broncho-alveolar lavage cultures found community-acquired Acinetobacter calcoaceticus-baumannii complex. The clinical outcome was favourable after twenty-one days of antimicrobial treatment by piperacillin/tazobactam and amikacin then cefepime. Multilocus sequence typing (MLST) analyses identified an A. pittii ST249. Despite the atypical clinical presentation with an unexpected partial destruction of lung parenchyma, we found very low virulence potential of the A. pittii strain with nematode killing assays and biofilm formation test. The median time required to kill 50% of the nematodes was 7 ± 0.3 days for A. pittii ST249, 7 ± 0.2 days for A. baumanii NAB ST2 and 8 ± 0.2 days for E. coli OP50, (p > 0,05). A. pittii ST249 showed significantly slower biofilm formation than A. baumanii NAB ST2: BFI = 8.83 ± 0.59 vs 3.93 ± 0.27 at 2 h (p < 0.0001), BFI = 6.3 ± 0.17 vs 1.87 ± 0.12 at 3 h (p < 0.0001) and BFI = 3.67 ± 0.41 vs 1.7 ± 0.06 after 4 h of incubation (p < 0.01). Community-acquired A. pittii should be considered as possible cause of sub-acute cavitary pneumonia particularly in a smoking and/or immunocompromised patient despite its low virulence potential.
-
Sevillano, Elena; Fernández, Elena; Bustamante, Zulema; Zabalaga, Silvia; Rosales, Ikerne; Umaran, Adelaida; Gallego, Lucía
2012-01-01
Acinetobacter baumannii is an emerging multidrug-resistant pathogen and very little information is available regarding its imipenem resistance in Latin American countries such as Bolivia. This study investigated the antimicrobial resistance profile of 46 clinical strains from different hospitals in Cochabamba, Bolivia, from March 2008 to July 2009, and the presence of carbapenemases as a mechanism of resistance to imipenem. Isolates were obtained from 46 patients (one isolate per patient; 30 males,16 females) with an age range of 1 day to 84 years, and were collected from different sample types, the majority from respiratory tract infections (17) and wounds (13). Resistance to imipenem was detected in 15 isolates collected from different hospitals of the city. These isolates grouped into the same genotype, named A, and were resistant to all antibiotics tested including imipenem, with susceptibility only to colistin. Experiments to detect carbapenemases revealed the presence of the OXA-58 carbapenemase. Further analysis revealed the location of the bla(OXA-58) gene on a 40 kb plasmid. To our knowledge, this is the first report of carbapenem resistance in A. baumannii isolates from Bolivia that is conferred by the OXA-58 carbapenemase. The presence of this gene in a multidrug-resistant clone and its location within a plasmid is of great concern with regard to the spread of carbapenem-resistant A. baumannii in the hospital environment in Bolivia.
-
Computational gene network study on antibiotic resistance genes of Acinetobacter baumannii.
Anitha, P; Anbarasu, Anand; Ramaiah, Sudha
2014-05-01
Multi Drug Resistance (MDR) in Acinetobacter baumannii is one of the major threats for emerging nosocomial infections in hospital environment. Multidrug-resistance in A. baumannii may be due to the implementation of multi-combination resistance mechanisms such as β-lactamase synthesis, Penicillin-Binding Proteins (PBPs) changes, alteration in porin proteins and in efflux pumps against various existing classes of antibiotics. Multiple antibiotic resistance genes are involved in MDR. These resistance genes are transferred through plasmids, which are responsible for the dissemination of antibiotic resistance among Acinetobacter spp. In addition, these resistance genes may also have a tendency to interact with each other or with their gene products. Therefore, it becomes necessary to understand the impact of these interactions in antibiotic resistance mechanism. Hence, our study focuses on protein and gene network analysis on various resistance genes, to elucidate the role of the interacting proteins and to study their functional contribution towards antibiotic resistance. From the search tool for the retrieval of interacting gene/protein (STRING), a total of 168 functional partners for 15 resistance genes were extracted based on the confidence scoring system. The network study was then followed up with functional clustering of associated partners using molecular complex detection (MCODE). Later, we selected eight efficient clusters based on score. Interestingly, the associated protein we identified from the network possessed greater functional similarity with known resistance genes. This network-based approach on resistance genes of A. baumannii could help in identifying new genes/proteins and provide clues on their association in antibiotic resistance. Copyright © 2014 Elsevier Ltd. All rights reserved.
-
Wei, Jun-Rong; Richie, Daryl L.; Mostafavi, Mina; Metzger, Louis E.; Rath, Christopher M.; Sawyer, William S.; Takeoka, Kenneth T.
2017-01-01
ABSTRACT Acinetobacter baumannii ATCC 19606 can grow without lipid A, the major component of lipooligosaccharide. However, we previously reported that depletion of LpxH (the fourth enzyme in the lipid A biosynthetic pathway) prevented growth of this strain due to toxic accumulation of lipid A pathway intermediates. Here, we explored whether a similar phenomenon occurred with depletion of LpxK, a kinase that phosphorylates disaccharide 1-monophosphate (DSMP) at the 4′ position to yield lipid IVA. An A. baumannii ATCC 19606 derivative with LpxK expression under the control of an isopropyl β-d-1-thiogalactopyranoside (IPTG)-regulated expression system failed to grow without induction, indicating that LpxK is essential for growth. Light and electron microscopy of LpxK-depleted cells revealed morphological changes relating to the cell envelope, consistent with toxic accumulation of lipid A pathway intermediates disrupting cell membranes. Using liquid chromatography-mass spectrometry (LCMS), cellular accumulation of the detergent-like pathway intermediates DSMP and lipid X was shown. Toxic accumulation was further supported by restoration of growth upon chemical inhibition of LpxC (upstream of LpxK and the first committed step of lipid A biosynthesis) using CHIR-090. Inhibitors of fatty acid synthesis also abrogated the requirement for LpxK expression. Growth rescue with these inhibitors was possible on Mueller-Hinton agar but not on MacConkey agar. The latter contains outer membrane-impermeable bile salts, suggesting that despite growth restoration, the cell membrane permeability barrier was not restored. Therefore, LpxK is essential for growth of A. baumannii, since loss of LpxK causes accumulation of detergent-like pathway intermediates that inhibit cell growth. IMPORTANCE Acinetobacter baumannii is a Gram-negative pathogen for which new therapies are needed. The lipid A biosynthetic pathway has several potential enzyme targets for the development of anti
-
Karumathil, Deepti P; Nair, Meera Surendran; Gaffney, James; Kollanoor-Johny, Anup; Venkitanarayanan, Kumar
2018-01-01
Multi-drug resistant (MDR) Acinetobacter baumannii is a major nosocomial pathogen causing a wide range of clinical conditions with significant mortality rates. A. baumannii strains are equipped with a multitude of antibiotic resistance mechanisms, rendering them resistant to most of the currently available antibiotics. Thus, there is a critical need to explore novel strategies for controlling antibiotic resistance in A. baumannii . This study investigated the efficacy of two food-grade, plant-derived antimicrobials (PDAs), namely trans -cinnamaldehyde (TC) and eugenol (EG) in decreasing A. baumannii 's resistance to seven β-lactam antibiotics, including ampicillin, methicillin, meropenem, penicillin, aztreonam, amoxicillin, and piperacillin. Two MDR A. baumannii isolates (ATCC 17978 and AB 251847) were separately cultured in tryptic soy broth (∼6 log CFU/ml) containing the minimum inhibitory concentration (MIC) of TC or EG with or without the MIC of each antibiotic at 37°C for 18 h. A. baumannii strains not exposed to the PDAs or antibiotics served as controls. Following incubation, A. baumannii counts were determined by broth dilution assay. In addition, the effect of PDAs on the permeability of outer membrane and efflux pumps in A. baumannii was measured. Further, the effect of TC and EG on the expression of A. baumannii genes encoding resistance to β-lactam antibiotics ( blaP ), efflux pumps ( adeABC ), and multi-drug resistant protein ( mdrp ) was studied using real-time quantitative PCR (RT-qPCR). The experiment was replicated three times with duplicate samples of each treatment and control. The results from broth dilution assay indicated that both TC and EG in combination with antibiotics increased the sensitivity of A. baumannii to all the tested antibiotics ( P < 0.05). The two PDAs inhibited the function of A. baumannii efflux pump, (AdeABC), but did not increase the permeability of its outer membrane. Moreover, RT-qPCR data revealed that TC and EG
-
Ahmed, S S; Alp, E; Ulu-Kilic, A; Dinc, G; Aktas, Z; Ada, B; Bagirova, F; Baran, I; Ersoy, Y; Esen, S; Guven, T G; Hopman, J; Hosoglu, S; Koksal, F; Parlak, E; Yalcin, A N; Yilmaz, G; Voss, A; Melchers, W
2016-09-01
Epidemic clones of Acinetobacter baumannii, described as European clones I, II, and III, are associated with hospital epidemics throughout the world. We aimed to determine the molecular characteristics and genetic diversity between European clones I, II, and III from Turkey and Azerbaijan. In this study, a total of 112 bloodstream isolates of carbapenem-resistant Acinetobacter spp. were collected from 11 hospitals across Turkey and Azerbaijan. The identification of Acinetobacter spp. using conventional and sensitivity tests was performed by standard criteria. Multiplex polymerase chain reaction (PCR) was used to detect OXA carbapenemase-encoding genes (bla OXA-23-like, bla OXA-24-like, bla OXA-51-like, and bla OXA-58-like). Pulsed-field gel electrophoresis (PFGE) typing was used to investigate genetic diversity. The bla OXA-51-like gene was present in all 112 isolates, 75 (67 %) carried bla OXA-23-like, 7 (6.2 %) carried bla OXA-58-like genes, and 5 (4.5 %) carried bla OXA-24-like genes. With a 90 % similarity cut-off value, 15 clones and eight unique isolates were identified. The largest clone was cluster D, with six subtypes. Isolates from clusters D and I were widely spread in seven different geographical regions throughout Turkey. However, F cluster was found in the northern and eastern regions of Turkey. EU clone I was grouped within J cluster with three isolates found in Antalya, Istanbul, and Erzurum. EU clone II was grouped in the U cluster with 15 isolates and found in Kayseri and Diyarbakır. The bla OXA-24-like gene in carbapenemases was identified rarely in Turkey and has been reported for the first time from Azerbaijan. Furthermore, this is the first multicenter study in Turkey and Azerbaijan to identify several major clusters belonging to European clones I and II of A. baumannii.
-
Kim, Si-Hyun; Park, Chulmin; Chun, Hye-Sun; Choi, Jae-Ki; Lee, Hyo-Jin; Cho, Sung-Yeon; Park, Sun Hee; Choi, Su-Mi; Choi, Jung-Hyun; Yoo, Jin-Hong
2016-01-01
With the rise in multidrug-resistant (MDR) bacterial infections, there has been increasing interest in combinations of ≥2 antimicrobial agents with synergistic effects. We established an MDR bacterial strain library to screen for in vitro antimicrobial synergy by using a broth microdilution checkerboard method and high-throughput luciferase-based bacterial cell viability assay. In total, 39 MDR bacterial strains, including 23 carbapenem-resistant gram-negative bacteria, 9 vancomycin-intermediate Staphylococcus aureus, and 7 vancomycin-resistant Enterococcus faecalis, were used to screen for potential antimicrobial synergies. Synergies were more frequently identified with combinations of imipenem plus trimethoprim–sulfamethoxazole for carbapenem-resistant Acinetobacter baumannii in the library. To verify this finding, we tested 34 A. baumannii clinical isolates resistant to both imipenem and trimethoprim–sulfamethoxazole by the checkerboard method. The imipenem plus trimethoprim–sulfamethoxazole combination showed synergy in the treatment of 21 (62%) of the clinical isolates. The results indicate that pilot screening for antimicrobial synergy in the MDR bacterial strain library could be valuable in the selection of combination therapeutic regimens to treat MDR bacterial infections. Further studies are warranted to determine whether this screening system can be useful to screen for the combined effects of conventional antimicrobials and new-generation antimicrobials or nonantimicrobials. PMID:26974861
-
Novel use of antimicrobial hand sanitizer in treatment of nosocomial acinetobacter infection.
Donahue, Meghan; Watson, Luke R; Torress-Cook, Alfonso; Watson, Paul A
2009-01-01
Colonization of wounds with multidrug-resistant organisms is a difficult orthopedic problem. Acinetobacter infections are especially difficult because they are resistant to all currently available antibiotics. We present the use of a novel skin sanitizer, Stay Byotrol Clean (Byotrol Inc, Spartanburg, South Carolina), to treat a multidrug-resistant wound infection. A 31-year-old T10 paraplegic man presented with chronic bilateral stage IV decubitus trochanteric ulcers. Cultures grew methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus. The ulcers were initially treated with irrigation and debridement and vancomycin, levaquin, and cefepime. After 4 months of aggressive treatment, the cultures continued to be positive for Escherichia coli and Acinetobacter baumannii. The patient was started on amikacin and tigecycline. Despite 1 additional month of aggressive wound care, debridements, and intravenous antibiotics, the cultures continued to grow A baumannii and Pseudomonas aerug. The A baumannii was resistant to all available antibiotics tested. The ulcers were then treated with daily application of Stay Byotrol Clean hand and skin sanitizer. Four days later, cultures were negative for any bacterial growth, with no A baumannii. After 1 week, the ulcers showed new granulation tissue with no visible necrotic tissue. After 3 months of treatment, the ulcers had healed. Stay Byotrol Clean is nonirritating and contains no iodine or alcohol. It is currently being used for decolonization of patients on admission to the hospital, however, there is great potential for its use in wound treatment, preoperative surgical sterilization, and orthopedic devices.
-
Hakemi Vala, M.; Hallajzadeh, M.; Hashemi, A.; Goudarzi, H.; Tarhani, M.; Sattarzadeh Tabrizi, M.; Bazmi, F.
2014-01-01
Summary In this study, we evaluated the existence of classes A, B and D ß-lactamases among Pseudomonas aeruginosa (P.aeruginosa) and Acinetobacter baumannii (A.baumannii) strains isolated from burn patients in Tehran during the years 2012 and 2013. From these strains, the frequency of MBL (metallo-beta-lactamase) and ESBL (extended-spectrum beta-lactamase) producers were evaluated using CDDT (Combined Disk Diffusion Tests). The prevalence of some related genes, including blaIMP, blaVIM, blaSPM, blaKPC, blaGIM, blaDIM, blaBIC, blaOXA-48, blaCTX-M-15 and blaNDM genes, was evaluated using PCR and sequencing methods. Of the 75 non-fermenter isolates, 47 P.aeruginosa and 28 A.baumannii were isolated and identified. A high rate of resistance to common antibiotics was detected among A.baumannii isolates in particular, showing 100% resistance to 9 tested antibiotics. CDDT showed that 21 (28%) and 25 (34.25%) of the non-fermenter isolates were ESBL and MBL producers respectively. The prevalence of blaCTX-M-15 and blaIMP genes among the 75 non-fermenter isolates was 7 (9.3%) and 1 (1.3%), respectively. Fortunately, no other genes were detected in either of the non-fermenters. The mortality rate due to MBL-producing isolates was 5 (20%). This study showed specific resistance genes exist among some MBL and ESBL gram-negative non-fermenters which were isolated from burn patients in Tehran. PMID:25249841
-
Hakemi Vala, M; Hallajzadeh, M; Hashemi, A; Goudarzi, H; Tarhani, M; Sattarzadeh Tabrizi, M; Bazmi, F
2014-03-31
In this study, we evaluated the existence of classes A, B and D ß-lactamases among Pseudomonas aeruginosa (P.aeruginosa) and Acinetobacter baumannii (A.baumannii) strains isolated from burn patients in Tehran during the years 2012 and 2013. From these strains, the frequency of MBL (metallo-beta-lactamase) and ESBL (extended-spectrum beta-lactamase) producers were evaluated using CDDT (Combined Disk Diffusion Tests). The prevalence of some related genes, including blaIMP, blaVIM, blaSPM, blaKPC, blaGIM, blaDIM, blaBIC, blaOXA-48, blaCTX-M-15 and blaNDM genes, was evaluated using PCR and sequencing methods. Of the 75 non-fermenter isolates, 47 P.aeruginosa and 28 A.baumannii were isolated and identified. A high rate of resistance to common antibiotics was detected among A.baumannii isolates in particular, showing 100% resistance to 9 tested antibiotics. CDDT showed that 21 (28%) and 25 (34.25%) of the non-fermenter isolates were ESBL and MBL producers respectively. The prevalence of blaCTX-M-15 and blaIMP genes among the 75 non-fermenter isolates was 7 (9.3%) and 1 (1.3%), respectively. Fortunately, no other genes were detected in either of the non-fermenters. The mortality rate due to MBL-producing isolates was 5 (20%). This study showed specific resistance genes exist among some MBL and ESBL gram-negative non-fermenters which were isolated from burn patients in Tehran.
-
Bioinformatic analysis of phage AB3, a phiKMV-like virus infecting Acinetobacter baumannii.
Zhang, J; Liu, X; Li, X-J
2015-01-16
The phages of Acinetobacter baumannii has drawn increasing attention because of the multi-drug resistance of A. baumanni. The aim of this study was to sequence Acinetobacter baumannii phage AB3 and conduct bioinformatic analysis to lay a foundation for genome remodeling and phage therapy. We isolated and sequenced A. baumannii phage AB3 and attempted to annotate and analyze its genome. The results showed that the genome is a double-stranded DNA with a total length of 31,185 base pairs (bp) and 97 open reading frames greater than 100 bp. The genome includes 28 predicted genes, of which 24 are homologous to phage AB1. The entire coding sequence is located on the negative strand, representing 90.8% of the total length. The G+C mol% was 39.18%, without areas of high G+C content over 200 bp in length. No GC island, tRNA gene, or repeated sequence was identified. Gene lengths were 120-3099 bp, with an average of 1011 bp. Six genes were found to be greater than 2000 bp in length. Genomic alignment and phylogenetic analysis of the RNA polymerase gene showed that similar to phage AB1, phage AB3 is a phiKMV-like virus in the T7 phage family.
-
Jones, Rheinallt M.; Pagmantidis, Vassilis; Williams, Peter A.
2000-01-01
A 5-kbp region upstream of the are-ben-cat genes was cloned from Acinetobacter sp. strain ADP1, extending the supraoperonic cluster of catabolic genes to 30 kbp. Four open reading frames, salA, salR, salE, and salD, were identified from the nucleotide sequence. Reverse transcription-PCR studies suggested that these open reading frames are organized into two convergent transcription units, salAR and salDE. The salE gene, encoding a protein of 239 residues, was ligated into expression vector pET5a. Its product, SalE, was shown to have esterase activity against short-chain alkyl esters of 4-nitrophenol but was also able to hydrolyze ethyl salicylate to ethanol and salicylic acid. A mutant of ADP1 with a Kmr cassette introduced into salE had lost the ability to utilize only ethyl and methyl salicylates of the esters tested as sole carbon sources, and no esterase activity against ethyl salicylate could be detected in cell extracts. SalE was induced during growth on ethyl salicylate but not during growth on salicylate itself. salD encoded a protein of undetermined function with homologies to the Escherichia coli FadL membrane protein, which is involved in facilitating fatty acid transport, and a number of other proteins detected during aromatic catabolism, which may also function in hydrocarbon transport or uptake processes. A Kmr cassette insertion in salD deleteriously affected cell growth and viability. The salA and salR gene products closely resemble two Pseudomonas proteins, NahG and NahR, respectively encoding salicylate hydroxylase and the LysR family regulator of both salicylate and naphthalene catabolism. salA was cloned into pUC18 together with salR and salE, and its gene product showed salicylate-inducible hydroxylase activity against a range of substituted salicylates, with the same relative specific activities as found in wild-type ADP1 grown on salicylate. Mutations involving insertion of Kmr cassettes into salA and salR eliminated expression of salicylate
-
Task force on management and prevention of Acinetobacter baumannii infections in the ICU.
Garnacho-Montero, José; Dimopoulos, George; Poulakou, Garyphallia; Akova, Murat; Cisneros, José Miguel; De Waele, Jan; Petrosillo, Nicola; Seifert, Harald; Timsit, Jean François; Vila, Jordi; Zahar, Jean-Ralph; Bassetti, Matteo
2015-12-01
Acinetobacter baumannii constitutes a dreadful problem in many ICUs worldwide. The very limited therapeutic options available for these organisms are a matter of great concern. No specific guidelines exist addressing the prevention and management of A. baumannii infections in the critical care setting. Clinical microbiologists, infectious disease specialists and intensive care physicians were invited by the Chair of the Infection Section of the ESICM to participate in a multidisciplinary expert panel. After the selection of clinically relevant questions, this document provides recommendations about the use of microbiological techniques for identification of A. baumannii in clinical laboratories, antibiotic therapy for severe infections and recommendations to control this pathogen in outbreaks and endemic situations. Evidence supporting each statement was graded according to the European Society of Clinical Microbiology and Infection Diseases (ESCMID) grading system. Empirical coverage of A. baumannii is recommended in severe infections (severe sepsis or septic shock) occurring during an A. baumannii outbreak, in an endemic setting, or in a previously colonized patient. For these cases, a polymyxin is suggested as part of the empirical treatment in cases of a high suspicion of a carbapenem-resistant (CR) A. baumannii strain. An institutional program including staff education, promotion of hand hygiene, strict contact and isolation precautions, environmental cleaning, targeted active surveillance, and antimicrobial stewardship should be instituted and maintained to combat outbreaks and endemic situations. Specific recommendations about prevention and management of A. baumannii infections in the ICU were elaborated by this multidisciplinary panel. The paucity of randomized controlled trials is noteworthy, so these recommendations are mainly based on observational studies and pharmacodynamics modeling.
-
Gagnaire, J; Gagneux-Brunon, A; Pouvaret, A; Grattard, F; Carricajo, A; Favier, H; Mattei, A; Pozzetto, B; Nuti, C; Lucht, F; Berthelot, P; Botelho-Nevers, E
2017-06-01
We aimed to describe the management of a carbapenemase-producing Acinetobacter baumannii (CP-AB) outbreak using the Outbreak Reports and Intervention Studies of Nosocomial Infection (ORION) statement. We also aimed to evaluate the cost of the outbreak and simulate costs if a dedicated unit to manage such outbreak had been set-up. We performed a prospective epidemiological study. Multiple interventions were implemented including cohorting measures and limitation of admissions. Cost estimation was performed using administrative local data. Five patients were colonized with CP-AB and hospitalized in the neurosurgery ward. The index case was a patient who had been previously hospitalized in Portugal. Four secondary colonized patients were further observed within the unit. The strains of A. baumannii were shown to belong to the same clone and all of them produced an OXA-23 carbapenemase. The closure of the ward associated with the discharge of the five patients in a cohorting area of the Infectious Diseases Unit with dedicated staff put a stop to the outbreak. The estimated cost of this 17-week outbreak was $474,474. If patients had been managed in a dedicated unit - including specific area for cohorting of patients and dedicated staff - at the beginning of the outbreak, the estimated cost would have been $189,046. Controlling hospital outbreaks involving multidrug-resistant bacteria requires a rapid cohorting of patients. Using simulation, we highlighted cost gain when using a dedicated cohorting unit strategy for such an outbreak. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
-
Biglari, Shirin; Hanafiah, Alfizah; Mohd Puzi, Shaliawani; Ramli, Ramliza; Rahman, Mostafizur; Lopes, Bruno Silvester
2017-07-01
Multidrug-resistant (MDR) Acinetobacter baumannii has increasingly emerged as an important nosocomial pathogen. The aim of this study was to determine the resistance profiles and genetic diversity in A. baumannii clinical isolates in a tertiary medical center in Malaysia. The minimum inhibitory concentrations of carbapenems (imipenem and meropenem), cephalosporins (ceftazidime and cefepime), and ciprofloxacin were determined by E-test. PCR and sequencing were carried out for the detection of antibiotic resistance genes and mutations. Clonal relatedness among A. baumannii isolates was determined by REP-PCR. Sequence-based typing of OXA-51 and multilocus sequence typing were performed. One hundred twenty-five of 162 (77.2%) A. baumannii isolates had MDR phenotype. From the 162 A. baumannii isolates, 20 strain types were identified and majority of A. baumannii isolates (66%, n = 107) were classified as strain type 1 and were positive for ISAba1-bla OXA-23 and ISAba1-bla ADC and had mutations in both gyrA and parC genes at positions, 83 and 80, resulting in serine-to-leucine conversion. REP-PCR analysis showed 129 REP types that generated 31 clones with a 90% similarity cutoff value. OXA-66 variant of the bla OXA-51-like genes was predominantly detected among our A. baumannii clinical isolates belonging to ST195 (found in six clones: 1, 8, 9, 19, 27, and 30) and ST208 (found in clone 21). The study helps us in understanding the genetic diversity of A. baumannii isolates in our setting and confirms that international clone II is the most widely distributed clone in Universiti Kebangsaan Malaysia Medical Centre, Malaysia.
-
Outbreak of resistant Acinetobacter baumannii- measures and proposal for prevention and control.
Romanelli, Roberta Maia de Castro; Jesus, Lenize Adriana de; Clemente, Wanessa Trindade; Lima, Stella Sala Soares; Rezende, Edna Maria; Coutinho, Rosane Luiza; Moreira, Ricardo Luiz Fontes; Neves, Francelli Aparecida Cordeiro; Brás, Nelma de Jesus
2009-10-01
Acinetobacter baumannii colonization and infection, frequent in Intensive Care Unit (ICU) patients, is commonly associated with high morbimortality. Several outbreaks due to multidrug-resistant (MDR) A. baumanii have been reported but few of them in Brazil. This study aimed to identify risk factors associated with colonization and infection by MDR and carbapenem-resistant A. baumannii strains isolated from patients admitted to the adult ICU at HC/UFMG. A case-control study was performed from January 2007 to June 2008. Cases were defined as patients colonized or infected by MDR/carbapenem-resistant A. baumannii, and controls were patients without MDR/carbapenem-resistant A. baumannii isolation, in a 1:2 proportion. For statistical analysis, due to changes in infection control guidelines, infection criteria and the notification process, this study was divided into two periods. During the first period analyzed, from January to December 2007, colonization or infection by MDR/carbapenem-resistant A. baumannii was associated with prior infection, invasive device utilization, prior carbapenem use and clinical severity. In the multivariate analysis, prior infection and mechanical ventilation proved to be statistically significant risk factors. Carbapenem use showed a tendency towards a statistical association. During the second study period, from January to June 2008, variables with a significant association with MDR/carbapenem-resistant A. baumannii colonization/infection were catheter utilization, carbapenem and third-generation cephalosporin use, hepatic transplantation, and clinical severity. In the multivariate analysis, only CVC use showed a statistical difference. Carbapenem and third-generation cephalosporin use displayed a tendency to be risk factors. Risk factors must be focused on infection control and prevention measures considering A. baumanni dissemination.
-
Parra-Millán, Raquel; Guerrero-Gómez, David; Ayerbe-Algaba, Rafael; Pachón-Ibáñez, Maria Eugenia; Miranda-Vizuete, Antonio
2018-01-01
ABSTRACT Acinetobacter baumannii is a significant human pathogen associated with hospital-acquired infections. While adhesion, an initial and important step in A. baumannii infection, is well characterized, the intracellular trafficking of this pathogen inside host cells remains poorly studied. Here, we demonstrate that transcription factor EB (TFEB) is activated after A. baumannii infection of human lung epithelial cells (A549). We also show that TFEB is required for the invasion and persistence inside A549 cells. Consequently, lysosomal biogenesis and autophagy activation were observed after TFEB activation which could increase the death of A549 cells. In addition, using the Caenorhabditis elegans infection model by A. baumannii, the TFEB orthologue HLH-30 was required for survival of the nematode to infection, although nuclear translocation of HLH-30 was not required. These results identify TFEB as a conserved key factor in the pathogenesis of A. baumannii. IMPORTANCE Adhesion is an initial and important step in Acinetobacter baumannii infections. However, the mechanism of entrance and persistence inside host cells is unclear and remains to be understood. In this study, we report that, in addition to its known role in host defense against Gram-positive bacterial infection, TFEB also plays an important role in the intracellular trafficking of A. baumannii in host cells. TFEB was activated shortly after A. baumannii infection and is required for its persistence within host cells. Additionally, using the C. elegans infection model by A. baumannii, the TFEB orthologue HLH-30 was required for survival of the nematode to infection, although nuclear translocation of HLH-30 was not required. PMID:29600279
-
2012-01-01
Afghanistan.1-3 Multidrug-resistant (MDR) Acinetobacter baumannii-calcoaceticus complex (ABC), extended-spectrum b-lactamase ( ESBL )-producing Klebsiella...September 2008 were screened (nares for MRSA, axillae and groin for gram-negative organisms) for the presence of ABC, ESBL -producing K pneumoniae, and
-
Sun, Jun-Ren; Perng, Cherng-Lih; Chan, Ming-Chin; Morita, Yuji; Lin, Jung-Chung; Su, Chih-Mao; Wang, Wei-Yao; Chang, Tein-Yao; Chiueh, Tzong-Shi
2012-01-01
Over-expression of AdeABC efflux pump stimulated continuously by the mutated AdeRS two component system has been found to result in antimicrobial resistance, even tigecycline (TGC) resistance, in multidrug-resistant Acinetobacter baumannii (MRAB). Although the insertion sequence, ISAba1, contributes to one of the AdeRS mutations, the detail mechanism remains unclear. In the present study we collected 130 TGC-resistant isolates from 317 carbapenem resistant MRAB (MRAB-C) isolates, and 38 of them were characterized with ISAba1 insertion in the adeS gene. The relationship between the expression of AdeABC efflux pump and TGC resistant was verified indirectly by successfully reducing TGC resistance with NMP, an efflux pump inhibitor. Further analysis showed that the remaining gene following the ISAba1 insertion was still transcribed to generate a truncated AdeS protein by the Pout promoter on ISAba1 instead of frame shift or pre-termination. Through introducing a series of recombinant adeRS constructs into a adeRS knockout strain, we demonstrated the truncated AdeS protein was constitutively produced and stimulating the expression of AdeABC efflux pump via interaction with AdeR. Our findings suggest a mechanism of antimicrobial resistance induced by an aberrant cytoplasmic sensor derived from an insertion element. PMID:23166700
-
Powers, Rachel A.; Swanson, Hollister C.; Taracila, Magdalena A.; ...
2014-11-07
β-Lactam resistance in Acinetobacter baumannii presents one of the greatest challenges to contemporary antimicrobial chemotherapy. Much of this resistance to cephalosporins derives from the expression of the class C β-lactamase enzymes, known as Acinetobacter-derived cephalosporinases (ADCs). Currently, β-lactamase inhibitors are structurally similar to β-lactam substrates and are not effective inactivators of this class C cephalosporinase. Herein, two boronic acid transition state inhibitors (BATSIs S02030 and SM23) that are chemically distinct from β-lactams were designed and tested for inhibition of ADC enzymes. BATSIs SM23 and S02030 bind with high affinity to ADC-7, a chromosomal cephalosporinase from Acinetobacter baumannii (K i =more » 21.1 ± 1.9 nM and 44.5 ± 2.2 nM, respectively). The X-ray crystal structures of ADC-7 were determined in both the apo form (1.73 Å resolution) and in complex with S02030 (2.0 Å resolution). In the complex, S02030 makes several canonical interactions: the O1 oxygen of S02030 is bound in the oxyanion hole, and the R1 amide group makes key interactions with conserved residues Asn152 and Gln120. In addition, the carboxylate group of the inhibitor is meant to mimic the C 3/C 4 carboxylate found in β-lactams. The C 3/C 4 carboxylate recognition site in class C enzymes is comprised of Asn346 and Arg349 (AmpC numbering), and these residues are conserved in ADC-7. Interestingly, in the ADC-7/S02030 complex, the inhibitor carboxylate group is observed to interact with Arg340, a residue that distinguishes ADC-7 from the related class C enzyme AmpC. A thermodynamic analysis suggests that ΔH driven compounds may be optimized to generate new lead agents. In conclusion, the ADC-7/BATSI complex provides insight into recognition of non-β-lactam inhibitors by ADC enzymes and offers a starting point for the structure-based optimization of this class of novel β-lactamase inhibitors against a key resistance target.« less
-
Longkumer, Toshisangba; Kamireddy, Swetha; Muthyala, Venkateswar Reddy; Akbarpasha, Shaikh; Pitchika, Gopi Krishna; Kodetham, Gopinath; Ayaluru, Murali; Siddavattam, Dayananda
2013-01-01
While analyzing plasmids of Acinetobacter sp. DS002 we have detected a circular DNA molecule pTS236, which upon further investigation is identified as the genome of a phage. The phage genome has shown sequence similarity to the recently discovered Sphinx 2.36 DNA sequence co-purified with the Transmissible Spongiform Encephalopathy (TSE) particles isolated from infected brain samples collected from diverse geographical regions. As in Sphinx 2.36, the phage genome also codes for three proteins. One of them codes for RepA and is shown to be involved in replication of pTS236 through rolling circle (RC) mode. The other two translationally coupled ORFs, orf106 and orf96, code for coat proteins of the phage. Although an orf96 homologue was not previously reported in Sphinx 2.36, a closer examination of DNA sequence of Sphinx 2.36 revealed its presence downstream of orf106 homologue. TEM images and infection assays revealed existence of phage AbDs1 in Acinetobacter sp. DS002.
-
Longkumer, Toshisangba; Kamireddy, Swetha; Muthyala, Venkateswar Reddy; Akbarpasha, Shaikh; Pitchika, Gopi Krishna; Kodetham, Gopinath; Ayaluru, Murali; Siddavattam, Dayananda
2013-01-01
While analyzing plasmids of Acinetobacter sp. DS002 we have detected a circular DNA molecule pTS236, which upon further investigation is identified as the genome of a phage. The phage genome has shown sequence similarity to the recently discovered Sphinx 2.36 DNA sequence co-purified with the Transmissible Spongiform Encephalopathy (TSE) particles isolated from infected brain samples collected from diverse geographical regions. As in Sphinx 2.36, the phage genome also codes for three proteins. One of them codes for RepA and is shown to be involved in replication of pTS236 through rolling circle (RC) mode. The other two translationally coupled ORFs, orf106 and orf96, code for coat proteins of the phage. Although an orf96 homologue was not previously reported in Sphinx 2.36, a closer examination of DNA sequence of Sphinx 2.36 revealed its presence downstream of orf106 homologue. TEM images and infection assays revealed existence of phage AbDs1 in Acinetobacter sp. DS002. PMID:23867905
-
Rossolini, Gian Maria; Mantengoli, Elisabetta; Docquier, Jean-Denis; Musmanno, Rosa Anna; Coratza, Grazietta
2007-07-01
Microbial drug resistance is a growing problem of global magnitude. In gram-negative pathogens, the most important resistance problems are encountered in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter, with increasing trends observed for all major anti-gram-negative agents (beta-lactams, fluoroquinolones and aminoglycosides). A matter of major concern is the emergence of new beta-lactamases capable of degrading the expanded-spectrum cephalosporins and/or carbapenems, such as the extended-spectrum beta-lactamases (ESBLs) and the carbapenemases. These beta-lactamase genes are often associated with resistance determinants to non-beta-lactam agents (e.g. aminoglycosides and fluoroquinolones), and strains producing ESBLs or carbapenemases often exhibit complex multidrug resistant phenotypes and sometimes are panresistant. The problem is worsened by the dearth of new agents active on multidrug-resistant Gram-negatives in the pipeline. The importance to develop better strategies to control resistance is underscored.
-
Shin, Yong Kook; Oh, Nam Su; Lee, Hyun Ah; Choi, Jong-Woo
2014-01-01
The aim of this study was to evaluate the effect of proteolytic (Serratia liquefaciens, match %: 99.39) or lipolytic (Acinetobacter genomospecies 10, match %: 99.90) psychrotrophic bacteria (bacterial counts, analysis of free fatty acids (FFA) and analysis of free amino acids) on the microbial and chemical properties (yogurt composition), and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of yogurt during storage. Yogurts were prepared with raw milk preinoculated with each psychrotrophic bacteria. The total solid, fat, and protein content were not affected by preinoculation, but the pH of yogurt preinoculated with psychrotrophic bacteria was higher than in control. There was a dramatic increase in short chain free fatty acids among FFA in yogurt with Acinetobacter genomospecies 10. For 14 d of cold storage condition, SCFFA was 25.3 mg/kg to 34.4 mg/kg (1.36 times increased), MCFFA was 20.4 mg/kg to 25.7 mg/kg (1.26 times increased), and LCFFA was 240.2 mg/kg to 322.8 mg/kg (1.34 times increased). Serratia liquefaciens (match %: 99.39) in yogurt caused a greater accumulation of free amino acids (FAA), especially bitter peptides such as leucine, valine, arginine, and tyrosine, but SDS-PAGE showed that the inoculation of Serratia liquefaciens did not affect the degree of casein degradation during storage. Taken together, the excessive peptides and FFA in yogurt generated from psychrotrophic bacteria could develop off-flavors that degrade the quality of commercial yogurt products. PMID:26761293
-
DOE Office of Scientific and Technical Information (OSTI.GOV)
Keller, L.C.; Thompson, T.L.; Maxcy, R.B.
1982-02-01
A highly radiation-resistant member of the Moraxella-Acinetobacter group, isolate 4, obtained from meat, was studied to determine the effect of preexposure to UV radiation on subsequent UV light resistance. Cultures that were preexposed to UV light and incubated for a short time in plate count broth exhibited increased survival of a UV light challenge dose. This response was inhibited in the presence of chloramphenicol. Frequencies of mutation to streptomycin, trimethoprim, and sulfanilamide resistance remained the same after the induction of this survival response and were not altered by treatment with mutagens, with the exception of mutation to streptomycin resistance aftermore » ..gamma..-irradiation or nitrosoguanidine or methyl methane sulfonate treatment. The results indicated that isolate 4 has a UV light-inducible UV light resistance mechanism which is not associated with increased mutagenesis. The characteristics of the radiation resistance response in this organism are similar to those of certain other common food contaminants. Therefore, considered as part of the total microflora of meat, isolate 4 and the other radiation-resistant Moraxella-Acinetobacter isolates should not pose unique problems in a proposed radappertizaton process.« less
-
Resistant mechanisms and molecular epidemiology of imipenem-resistant Acinetobacter baumannii.
Xiao, Shu-Zhen; Chu, Hai-Qing; Han, Li-Zhong; Zhang, Zhe-Min; Li, Bing; Zhao, Lan; Xu, Liyun
2016-09-01
The aim of the study was to investigate the resistant mechanisms and homology of imipenem-resistant Acinetobacter baumannii (A. baumannii). A total of 46 non-duplicate imipenem‑resistant A. baumannii clinical isolates were collected from three tertiary hospitals between July, 2011 and June, 2012. The minimal inhibitory concentrations (MICs) of antimicrobial agents were determined using the agar dilution method. Phenylalanine‑arginine β-naphthylamide was used to detect the presence of the efflux pump-mediated resistant mechanism. Polymerase chain reaction was employed to amplify genes associated with drug resistance, including β‑lactamase genes, efflux pump genes and outer membrane protein gene CarO. A few amplicons were randomly selected and sequenced. Multilocus sequence analysis (MLST) was employed in typing A. baumanni. A. baumannii was resistant to imipenem, simultaneously showing resistance to several other antimicrobials. In addtition, 13 A. baumannii were found to mediate drug resistance through operation of the efflux pump. Of the various drug resistance genes tested, blaOXA‑51 was present in 46 isolates, blaOXA‑23 gene was present in 44 isolates and blaNDM gene was found in only one strain. Other drug resistant‑associated genes, including blaKPC, blaIMP, blaOXA-24, blaOXA‑58, blaSHV, blaGIM and blaVIM were not detected. Mutation of adeS and outer membrane protein gene CarO were found in a few of the imipenem‑resistant isolates. The MLST analysis revealed that all 46 clinical isolates were clustered into 11 genotypes and the most frequent genotype was ST208. In conclusion, β‑lactamase genes, genes involved in efflux pump and mutation of outer membrane protein encoding gene may be important in mediating imipenem resistance in A. baumannii. Of the 11 different genotypes, ST11 was shared by the majority of A. baumannii, which may be due to horizontal transfer of patients from hospitals.
-
Pourcel, Christine; Minandri, Fabrizia; Hauck, Yolande; D'Arezzo, Silvia; Imperi, Francesco; Vergnaud, Gilles; Visca, Paolo
2011-01-01
Acinetobacter baumannii is an important opportunistic pathogen responsible for nosocomial outbreaks, mostly occurring in intensive care units. Due to the multiplicity of infection sources, reliable molecular fingerprinting techniques are needed to establish epidemiological correlations among A. baumannii isolates. Multiple-locus variable-number tandem-repeat analysis (MLVA) has proven to be a fast, reliable, and cost-effective typing method for several bacterial species. In this study, an MLVA assay compatible with simple PCR- and agarose gel-based electrophoresis steps as well as with high-throughput automated methods was developed for A. baumannii typing. Preliminarily, 10 potential polymorphic variable-number tandem repeats (VNTRs) were identified upon bioinformatic screening of six annotated genome sequences of A. baumannii. A collection of 7 reference strains plus 18 well-characterized isolates, including unique types and representatives of the three international A. baumannii lineages, was then evaluated in a two-center study aimed at validating the MLVA assay and comparing it with other genotyping assays, namely, macrorestriction analysis with pulsed-field gel electrophoresis (PFGE) and PCR-based sequence group (SG) profiling. The results showed that MLVA can discriminate between isolates with identical PFGE types and SG profiles. A panel of eight VNTR markers was selected, all showing the ability to be amplified and good amounts of polymorphism in the majority of strains. Independently generated MLVA profiles, composed of an ordered string of allele numbers corresponding to the number of repeats at each VNTR locus, were concordant between centers. Typeability, reproducibility, stability, discriminatory power, and epidemiological concordance were excellent. A database containing information and MLVA profiles for several A. baumannii strains is available from http://mlva.u-psud.fr/. PMID:21147956
-
Srisrattakarn, Arpasiri; Lulitanond, Aroonlug; Wilailuckana, Chotechana; Charoensri, Nicha; Daduang, Jureerut; Chanawong, Aroonwadee
2017-09-01
To develop a simple gold nanoparticle (AuNP)-based colorimetric test, GoldNano Carb (GoldC), for detecting carbapenemase production in Gram-negative bacteria, compared with updated Carba NP (CNP) and CarbAcineto NP (CAcNP) tests by using PCR methods as gold standard. Ninety-nine carbapenemase-producing Enterobacteriaceae (CPE), Pseudomonas spp. and Acinetobacter spp. isolates and 89 non-CPE isolates were tested by the GoldC and CNP. Additionally, the CAcNP was performed in the Acinetobacter spp. isolates. The final imipenem (imipenem/cilastatin form) concentration was 5 mg/mL for all three tests. For the GoldC, the imipenem powder was added directly to bacterial cell suspension in distilled water prior to detection of acid product by the citrate-capped AuNP solution. An AuNP change from red to purple, blue or green indicates carbapenemase activity. The GoldC detected all carbapenemase producers except one OXA-23-like producer (99.0% sensitivity), whereas 11 carbapenemase producers (10 Acinetobacter and 1 P. aeruginosa) were CNP negative (88.9% sensitivity). However, the GoldC and CNP provided 100% and 98.6% sensitivity, respectively, for the CPE and Pseudomonas spp. Both tests gave one false positive from CTX-M-1-like-producing Enterobacter spp. (98.9% specificity). The GoldC and CAcNP detected 96.7% and 93.3% of the Acinetobacter spp. isolates, respectively. Interestingly, times to positivity by the GoldC were markedly shorter than those by the CNP (76.8% versus 36.2% positive at 5 min) and CAcNP (43.3% at 5 min versus 20% within 30 min). The GoldC is fast, easy, highly sensitive and inexpensive (∼$0.25 per test), suggesting that it may be suitable for routine carbapenemase detection in low-resource settings for infection control or epidemiological purposes. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
-
[Acinetobacter baumannii: an important pathogen with multidrug resistance in newborns].
Celik, Istemi Han; Demirel, Gamze; Tatar Aksoy, Hatice; Saygan, Sibel; Canpolat, Fuat Emre; Uras, Nurdan; Oğuz, Serife Suna; Erdeve, Omer; Dilmen, Uğur
2011-10-01
Nosocomial sepsis agents with multidrug resistance have led to higher morbidity and mortality in premature infants in the recent years. Acinetobacter baumannii has become a leading cause of nosocomial sepsis in several neonatal intensive care units. In this study, the demographic, clinic, microbiologic characteristics and risk factors of 21 premature infants hospitalized in newborn intensive care unit between January 2010-February 2011 and developed A.baumannii infection, have been evaluated retrospectively. The isolates were identified by conventional methods and antibiotic susceptibility tests were performed by Vitek 2 GN and AST-N090 using Vitek 2 Compact system (BioMerieux, France). A.baumannii was isolated from the blood samples of 10 patients, central venous catheter samples of three patients, CSF samples of two, tracheal aspirate of two and urine sample of one patient. In two patients both blood and central venous catheter samples and in one patient both blood and CSF samples revealed A.baumannii. Gestational age was between 22-30 weeks and birth weight was between 500-1320 grams (17 were < 1000 g) in 19 patients. A.baumannii caused early onset (≤ 3 days) sepsis in four, and late onset (≥ 4 days) sepsis in 17 patients. The main risk factors were detected as mechanical ventilation (n= 20, 95%), prematurity (n= 19, 91%), total parenteral nutrition (n= 17, 81%) and central catheter use (n= 14, 67%). Antibiotics with highest rates of susceptibility were gentamicin (18/21), amikacin (14/21), and colistin (10/21). Twenty (95%) isolates had multiple drug resistance. Amikacin, gentamicin, colistin and imipenem were used for treatment, however 12 infants, 8 of which due to sepsis, died. In conclusion, A.baumannii which is an important nosocomial sepsis agent with multidrug resistance, is increasing in incidence. To control Acinetobacter infections especially in low-birth weight infants, the use of invasive procedures, total parenteral nutrition and broad spectrum
-
Knezevic, Petar; Aleksic, Verica; Simin, Natasa; Svircev, Emilija; Petrovic, Aleksandra; Mimica-Dukic, Neda
2016-02-03
Traditional herbal medicine has become an important issue on the global scale during the past decade. Among drugs of natural origin, special place belongs to essential oils, known as strong antimicrobial agents that can be used to combat antibiotic-resistant bacteria. Eucalyptus camaldulensis leaves are traditional herbal remedy used for various purposes, including treatment of infections. The aim of this study was to determine antimicrobial potential of two E. camaldulensis essential oils against multi-drug resistant (MDR) Acinetobacter baumannii wound isolates and to examine possible interactions of essential oils with conventional antimicrobial agents. Chemical composition of essential oils was determined by gas chromatography-mass spectrometry analysis (GC-MS). MIC values of essential oils against A. baumannii strains were estimated by modified broth microdilution method. The components responsible for antimicrobial activity were detected by bioautographic analysis. The potential synergy between the essential oils and antibiotics (ciprofloxacin, gentamicin and polymyxin B) was examined by checkerboard method and time kill curve. The dominant components of both essential oils were spatulenol, cryptone, p-cimene, 1,8-cineole, terpinen-4-ol and β-pinene. The detected MICs for the E. camaldulensis essential oils were in range from 0.5 to 2 μl mL(-1). The bioautographic assay confirmed antibacterial activity of polar terpene compounds. In combination with conventional antibiotics (ciprofloxacin, gentamicin and polymyxin B), the examined essential oils showed synergistic antibacterial effect in most of the cases, while in some even re-sensitized MDR A. baumannii strains. The synergistic interaction was confirmed by time-kill curves for E. camaldulensis essential oil and polymyxin B combination which reduced bacterial count under detection limit very fast, i.e. after 6h of incubation. The detected anti-A. baumannii activity of E. camaldulensis essential oils
-
Mathlouthi, Najla; Areig, Zaynab; Al Bayssari, Charbel; Bakour, Sofiane; Ali El Salabi, Allaaeddin; Ben Gwierif, Salha; Zorgani, Abdulaziz A; Ben Slama, Karim; Chouchani, Chedly; Rolain, Jean-Marc
2015-06-01
The aim of the present study was to investigate the molecular mechanism of carbapenem resistance in Pseudomonas aeruginosa and Acinetobacter baumannii clinical isolates recovered from Libyan hospitals between April 2013 and April 2014. In total, 49 strains (24 P. aeruginosa and 25 A. baumannii) were isolated, including 21 P. aeruginosa and 22 A. baumannii isolates (87.75%) resistant to imipenem (minimum inhibitory concentrations ≥16 μg/ml). The blaVIM-2 gene was detected in 19 P. aeruginosa isolates. All imipenem-resistant P. aeruginosa isolates showed the presence of OprD mutations. Acquired OXA-carbapenemase-encoding genes were present in all A. baumannii isolates: blaOXA-23 (n=19) and blaOXA-24 (n=3). Finally, a total of 13 and 17 different sequence types were assigned to the 21 P. aeruginosa and the 22 A. baumannii carbapenem-resistant isolates, respectively. This study is the first report describing imipenem-resistant P. aeruginosa and A. baumannii isolated from patients in Libya. We report the first case of co-occurrence of blaVIM-2 with oprD porin loss in identical isolates of P. aeruginosa in Libya and demonstrate that these oprD mutations can be used as a tool to study the clonality in P. aeruginosa isolates. We also report the first identification of multidrug-resistant A. baumannii isolates harboring blaOXA-23-like, blaOXA-24-like, and blaOXA-48-like genes in Libya.
-
Ortega-de la Rosa, Nestor D; Vázquez-Vázquez, Jose L; Huerta-Ochoa, Sergio; Gimeno, Miquel; Gutiérrez-Rojas, Mariano
2018-06-01
Acinetobacter species are identified as producing surface-active and emulsifying molecules known as bioemulsifiers. Production, characterization and stability of bioemulsifiers produced by Acinetobacter bouvetii UAM25 were studied. A. bouvetii UAM25 grew in three different carbon and energy sources: ethanol, a glycerol-hexadecane mixture and waste cooking oil in an airlift bioreactor, showing that bioemulsifier production was growth associated. The three purified bioemulsifiers were lipo-heteropolysaccharides of high molecular weight (4866 ± 533 and 462 ± 101 kDa). The best carbon source and energy for bioemulsifier production was wasted cooking oil, with a highest emulsifying capacity (76.2 ± 3.5 EU mg -1 ) as compared with ethanol (46.6 ± 7.1 EU mg -1 ) and the glycerol-hexadecane mixture (49.5 ± 4.2 EU mg -1 ). The three bioemulsifiers in our study displayed similar macromolecular structures, regardless of the nature (hydrophobic or hydrophilic) of the carbon and energy source. Bioemulsifiers did not decrease surface tension, but the emulsifying capacity of all of them was retained under extreme variation in salinity (0-50 g NaCl L -1 ), pH (3-10) and temperature (25-121 °C), indicative of remarkable stability. These findings contribute to understanding of the relationship between: production, physical properties, chemical composition and stability of bioemulsifiers for their potential applications in biotechnology, such as bioremediation of hydrocarbon-contaminated soil and water.
-
Coelho, Juliana M.; Turton, Jane F.; Kaufmann, Mary E.; Glover, Judith; Woodford, Neil; Warner, Marina; Palepou, Marie-France; Pike, Rachel; Pitt, Tyrone L.; Patel, Bharat C.; Livermore, David M.
2006-01-01
From late 2003 to the end of 2005, the Health Protection Agency's national reference laboratories received approximately 1,600 referrals of Acinetobacter spp., including 419 and 58 examples, respectively, of two carbapenem-resistant Acinetobacter baumannii lineages, designated OXA-23 clones 1 and 2. Representatives of these clones were obtained from 40 and 8 hospitals, respectively, in London or elsewhere in Southeast England. Both clones had blaOXA-23-like genes, as well as the intrinsic (but downregulated) blaOXA-51-like carbapenemase genes typical of A. baumannii. Both were highly multiresistant: only colistin and tigecycline remained active versus OXA-23 clone 1 isolates; OXA-23 clone 2 isolates were also susceptible to amikacin and minocycline. These lineages increase the burden created by the southeast (SE) clone, a previously reported A. baumannii lineage with variable carbapenem resistance contingent on upregulation of the blaOXA-51-like gene. Known since 2000, the SE clone had been referred from over 40 hospitals by the end of 2005, with 627 representatives received by the reference laboratories. The OXA-23 clone 2 is now in decline, but OXA-23 clone 1 continues to be referred from new sites, as does the SE clone. Their spread is forcing the use of unorthodox therapies, principally colistin and tigecycline, although the optimal regimens remain uncertain. PMID:17021090
-
Hassan, Karl A; Liu, Qi; Henderson, Peter J F; Paulsen, Ian T
2015-02-10
Multidrug efflux systems are a major cause of resistance to antimicrobials in bacteria, including those pathogenic to humans, animals, and plants. These proteins are ubiquitous in these pathogens, and five families of bacterial multidrug efflux systems have been identified to date. By using transcriptomic and biochemical analyses, we recently identified the novel AceI (Acinetobacter chlorhexidine efflux) protein from Acinetobacter baumannii that conferred resistance to the biocide chlorhexidine, via an active efflux mechanism. Proteins homologous to AceI are encoded in the genomes of many other bacterial species and are particularly prominent within proteobacterial lineages. In this study, we expressed 23 homologs of AceI and examined their resistance and/or transport profiles. MIC analyses demonstrated that, like AceI, many of the homologs conferred resistance to chlorhexidine. Many of the AceI homologs conferred resistance to additional biocides, including benzalkonium, dequalinium, proflavine, and acriflavine. We conducted fluorimetric transport assays using the AceI homolog from Vibrio parahaemolyticus and confirmed that resistance to both proflavine and acriflavine was mediated by an active efflux mechanism. These results show that this group of AceI homologs represent a new family of bacterial multidrug efflux pumps, which we have designated the proteobacterial antimicrobial compound efflux (PACE) family of transport proteins. Bacterial multidrug efflux pumps are an important class of resistance determinants that can be found in every bacterial genome sequenced to date. These transport proteins have important protective functions for the bacterial cell but are a significant problem in the clinical setting, since a single efflux system can mediate resistance to many structurally and mechanistically diverse antibiotics and biocides. In this study, we demonstrate that proteins related to the Acinetobacter baumannii AceI transporter are a new class of multidrug
-
Gao, Wei-Wei; Gopala, Lavanya; Bheemanaboina, Rammohan R Yadav; Zhang, Guo-Biao; Li, Shuo; Zhou, Cheng-He
2018-02-25
Aminothiazolyl berberine derivatives as potentially antimicrobial agents were designed and synthesized in an effort to overcome drug resistance. The antimicrobial assay revealed that some target compounds exhibited significantly inhibitory efficiencies toward bacteria and fungi including drug-resistant pathogens, and the aminothiazole and Schiff base moieties were helpful structural fragments for aqueous solubility and antibacterial activity. Especially, aminothiazolyl 9-hexyl berberine 9c and 2,4-dichlorobenzyl derivative 18a exhibited good activities (MIC = 2 nmol/mL) against clinically drug-resistant Gram-negative Acinetobacter baumanii with low cytotoxicity to hepatocyte LO2 cells, rapidly bactericidal effects and quite slow development of bacterial resistance toward A. baumanii. Molecular modeling indicated that compounds 9c and 18a could bind with GLY-102, ARG-136 and/or ALA-100 residues of DNA gyrase through hydrogen bonds. It was found that compounds 9c and 18a were able to disturb the drug-resistant A. baumanii membrane effectively, and molecule 9c could not only intercalate but also cleave bacterial DNA isolated from resistant A. baumanii, which might be the preliminary antibacterial action mechanism of inhibiting the growth of A. baumanii strain. In particular, the combination use of compound 9c with norfloxacin could enhance the antibacterial activity, broaden antibacterial spectrum and overcome the drug resistance. Copyright © 2018 Elsevier Masson SAS. All rights reserved.
-
Wang, Ching-Hsun; Li, Jin-Feng; Huang, Li-Yueh; Lin, Fu-Mei; Yang, Ya-Sung; Siu, L Kristopher; Chang, Feng-Yee; Lin, Jung-Chung
2017-10-01
This study describes an outbreak caused by imipenem-resistant Acinetobacter baumannii (IRAB) involving 2 general wards at the Penghu branch of Tri-Service General Hospital. Clinical data obtained from the patients with IRAB during an outbreak from May 2014-October 2014 were reviewed. Microbiologic sampling from the environment and the hands of health care workers (HCWs) was performed. Clinical isolates from case patients were genotyped using pulsed-field gel electrophoresis (PFGE). During the outbreak period, 12 patients were colonized or infected with IRAB. The hospital room environments of the case patients were contaminated with IRAB. Hands of nurses and physicians were not colonized with IRAB, but the hands of 2 bedside caregivers of case patients were colonized with IRAB. The PFGE analysis revealed that at least 2 major genetically distinct strains disseminated between 2 different wards. After implementation of infection control measures with a cohort of nursing patients, hand hygiene education for caregivers who had not received instructions before the outbreak, and a critical value alert system to notify case patients, the outbreak was controlled successfully. This outbreak study highlights the importance of adherence to hand hygiene by all HCWs to prevent the dissemination of multidrug-resistant organisms. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
-
Takahashi, Akira; Yuki, Norikatsu; Kaji, Rumi; Takahashi, Takuya; Nomoto, Koji
2016-01-01
This study investigated the ability of the probiotic Bifidobacterium breve strain Yakult (BbY) to protect against infection, as well as the potentiation of BbY activity by the synbiotic combination of BbY and prebiotic galactooligosaccharides (GOS). The study employed a mouse model of lethal intestinal multidrug-resistant Acinetobacter baumannii (MDRAb) infection. The endogenous intestinal microbiota was disrupted by the administration of multiple antibiotics, causing the loss of endogenous Bifidobacterium. Oral infection of these mice with MDRAb resulted in marked growth of this organism. Additional treatment of the infected mice with a sublethal dose of 5-fluorouracil (5-FU) induced systemic invasion by MDRAb and subsequent animal death. The continuous oral administration of BbY increased the survival rate and inhibited the intestinal growth and invasion by MDRAb in the infection model. Disruptions of the intestinal environment and barrier function in the infected mice were attenuated by BbY. Protection against the MDRAb infection was markedly potentiated by a synbiotic combination of BbY and GOS, although GOS by itself did not provide protection. Negative correlations were observed between intestinal MDRAb and BbY counts or acetic acid levels; positive correlations were observed between acetic acid levels and intestinal epithelium expression of tight-junction-related genes. These results demonstrated that the probiotic and synbiotic markedly potentiated protection against fatal intestinal infection caused by a multidrug-resistant bacterium. Probiotics and synbiotics are presumed to provide protection by compensation for the disrupted indigenous populations, thereby maintaining the intestinal environments and barrier functions otherwise targeted during opportunistic infection by MDRAb. PMID:26953197
-
Khoramnia, Anahita; Ebrahimpour, Afshin; Beh, Boon Kee; Lai, Oi Ming
2011-01-01
The lipase production ability of a newly isolated Acinetobacter sp. in submerged (SmF) and solid-state (SSF) fermentations was evaluated. The results demonstrated this strain as one of the rare bacterium, which is able to grow and produce lipase in SSF even more than SmF. Coconut oil cake as a cheap agroindustrial residue was employed as the solid substrate. The lipase production was optimized in both media using artificial neural network. Multilayer normal and full feed forward backpropagation networks were selected to build predictive models to optimize the culture parameters for lipase production in SmF and SSF systems, respectively. The produced models for both systems showed high predictive accuracy where the obtained conditions were close together. The produced enzyme was characterized as a thermotolerant lipase, although the organism was mesophile. The optimum temperature for the enzyme activity was 45°C where 63% of its activity remained at 70°C after 2 h. This lipase remained active after 24 h in a broad range of pH (6-11). The lipase demonstrated strong solvent and detergent tolerance potentials. Therefore, this inexpensive lipase production for such a potent and industrially valuable lipase is promising and of considerable commercial interest for biotechnological applications.
-
Chang, Kai-Chih; Chung, Chin-Yi; Yeh, Chen-Hsing; Hsu, Kuo-Hsiu; Chin, Ya-Ching; Huang, Sin-Siang; Liu, Bo-Rong; Chen, Hsi-An; Hu, Anren; Soo, Po-Chi; Peng, Wen-Ping
2018-04-01
The appearance and spread of carbapenem-resistant Acinetobacter baumannii (CRAB) pose a challenge for optimization of antibiotic therapies and outbreak preventions. The carbapenemase production can be detected through culture-based methods (e.g. Modified Hodge Test-MHT) and DNA based methods (e.g. Polymerase Chain Reaction-PCR). The culture-based methods are time-consuming, whereas those of PCR assays need only a few hours but due to its specificity, can only detect known genetic targets encoding carbapenem-resistance genes. Therefore, new approaches to detect carbapenemase-producing A. baumannii are of great importance. Here, we have developed a rapid and novel method using detonation nanodiamonds (DNDs) as a platform for concentration and extraction of A. baumannii carbapenemase-associated proteins prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF-MS) analysis. To concentrate and extract the A. baumannii carbapenemase-associated proteins, we tested several protein precipitation conditions and found a 0.5% trifluoroacetic acid (TFA) solution within the bacterial suspension could result in strong ion signals with DNDs. A total of 66 A. baumannii clinical-isolates including 51 carbapenem-resistant strains and 15 carbapenem-susceptible strains were tested. Our result showed that among the 51 carbapenem-resistant strains 49 strains had a signal at m/z ~40,279 (±87); among the 15 carbapenem-susceptible strains, 4 strains showed a signal at m/z ~40,279. With on-diamond digestion, we confirmed that the captured protein at m/z ~40,279 was related to ADC family extended-spectrum class C beta-lactamase, from A. baumannii. Using this ADC family protein as a biomarker (m/z ~ 40,279) for carbapenem susceptibility testing of A. baumannii, the sensitivity and the specificity could reach 96% and 73% as compared to traditional imipenem susceptibility testing (MIC results). However, the sensitivity and specificity of this method
-
Genetic Determinants of Intrinsic Colistin Tolerance in Acinetobacter baumannii
Hood, M. Indriati; Becker, Kyle W.; Roux, Christelle M.; Dunman, Paul M.
2013-01-01
Acinetobacter baumannii is a leading cause of multidrug-resistant infections worldwide. This organism poses a particular challenge due to its ability to acquire resistance to new antibiotics through adaptation or mutation. This study was undertaken to determine the mechanisms governing the adaptability of A. baumannii to the antibiotic colistin. Screening of a transposon mutant library identified over 30 genes involved in inducible colistin resistance in A. baumannii. One of the genes identified was lpsB, which encodes a glycosyltransferase involved in lipopolysaccharide (LPS) synthesis. We demonstrate that loss of LpsB function results in increased sensitivity to both colistin and cationic antimicrobial peptides of the innate immune system. Moreover, LpsB is critical for pathogenesis in a pulmonary model of infection. Taken together, these data define bacterial processes required for intrinsic colistin tolerance in A. baumannii and underscore the importance of outer membrane structure in both antibiotic resistance and the pathogenesis of A. baumannii. PMID:23230287
-
Hombach, Michael; Jetter, Marion; Blöchliger, Nicolas; Kolesnik-Goldmann, Natalia; Keller, Peter M; Böttger, Erik C
2018-01-01
Abstract Background We investigated the feasibility of rapid disc diffusion antibiotic susceptibility testing (rAST) with reading of inhibition zones after 6 and/or 8 h of incubation for Enterococcus faecalis, Enterococcus faecium, Pseudomonas aeruginosa and Acinetobacter baumannii. In addition, we evaluated discrimination of resistant populations from the WT populations at early timepoints and the requirement for clinical breakpoint adaptations for proper interpretation of rAST data. Methods In total, 815 clinical strains [E. faecalis (n = 135), E. faecium (n = 227), P. aeruginosa (n = 295) and A. baumannii (n = 158)] were included in this study. Disc diffusion plates were streaked, incubated and imaged using the WASPLabTM automation system. WT populations and non-WT populations were defined using epidemiological cut-offs. Results and conclusions rAST at 6 and 8 h was possible for A. baumannii and enterococci with readability of inhibition zones >90%. Overall categorical agreement of rAST at 6 h with AST at 18 h was 97.2%, 97.4% and 95.3% for E. faecalis, E. faecium and A. baumannii, respectively. With few exceptions, major categorization error rates were <1% for A. baumannii, and vancomycin-resistant E. faecium were clearly separated from the WT at 6 h. For P. aeruginosa the average readability of inhibition zones was 68.9% at 8 h and we found an overall categorical agreement of 94.8%. Adaptations of clinical breakpoints and/or introduction of technical buffer zones, preferably based on aggregated population data from various epidemiological settings, are required for proper interpretation of rAST. PMID:29186434
-
Ragàs, Xavier; Dai, Tianhong; Tegos, George P.; Agut, Montserrat; Nonell, Santi; Hamblin, Michael R.
2010-01-01
Background and Objective Phenothiazinium dyes have been reported to be effective photosensitizers inactivating a wide range of microorganisms in vitro after illumination with red light. However, their application in vivo has not extensively been explored. This study evaluates the bactericidal activity of phenothiazinium dyes against multidrug-resistant Acinetobacter baumannii both in vitro and in vivo. Study Design/Materials and Methods We report the investigation of toluidine blue O, methylene blue, 1,9-dimethylmethylene blue, and new methylene blue for photodynamic inactivation of multidrug-resistant A. baumannii in vitro. The most effective dye was selected to carry out in vivo studies using third-degree mouse burns infected with a bioluminescent A. baumannii strain, upon irradiation with a 652 nm noncoherent light source. The mice were imaged daily for 2 weeks to observe differences in the bioluminescence–time curve between the photodynamic therapy (PDT)-treated mice in comparison with untreated burns. Results All the dyes were effective in vitro against A. baumannii after 30 J/cm2 irradiation of 635 or 652 nm red light had been delivered, with more effective killing when the dye remained in solution. New methylene blue was the most effective of the four dyes, achieving a 3.2-log reduction of the bacterial luminescence during PDT in vivo after 360 J/cm2 and an 800 μM dye dose. Moreover, a statistically significant reduction of the area under the bioluminescence–time curve of PDT-treated mice was observed showing that the infection did not recur after PDT. Conclusions Phenothiazinium dyes, and especially new methylene blue, are potential photosensitizers for PDT to treat burns infected with multidrug-resistant A. baumannii in vivo. PMID:20583252
-
Pérez, Astrid; Gómez, Manuel J.; Gayoso, Carmen; Vallejo, Juan A.; Ohneck, Emily J.; Valle, Jaione; Actis, Luis A.; Beceiro, Alejandro; Bou, Germán
2017-01-01
Many strains of Acinetobacter baumannii have been described as being able to form biofilm. Small non-coding RNAs (sRNAs) control gene expression in many regulatory circuits in bacteria. The aim of the present work was to provide a global description of the sRNAs produced both by planktonic and biofilm-associated (sessile) cells of A. baumannii ATCC 17978, and to compare the corresponding gene expression profiles to identify sRNAs molecules associated to biofilm formation and virulence. sRNA was extracted from both planktonic and sessile cells and reverse transcribed. cDNA was subjected to 454-pyrosequencing using the GS-FLX Titanium chemistry. The global analysis of the small RNA transcriptome revealed different sRNA expression patterns in planktonic and biofilm associated cells, with some of the transcripts only expressed or repressed in sessile bacteria. A total of 255 sRNAs were detected, with 185 of them differentially expressed in the different types of cells. A total of 9 sRNAs were expressed only in biofilm cells, while the expression of other 21 coding regions were repressed only in biofilm cells. Strikingly, the expression level of the sRNA 13573 was 120 times higher in biofilms than in planktonic cells, an observation that prompted us to further investigate the biological role of this non-coding transcript. Analyses of an isogenic mutant and over-expressing strains revealed that the sRNA 13573 gene is involved in biofilm formation and attachment to A549 human alveolar epithelial cells. The present work serves as a basis for future studies examining the complex regulatory network that regulate biofilm biogenesis and attachment to eukaryotic cells in A. baumannii ATCC 17978. PMID:28763494
-
Potential of a lytic bacteriophage to disrupt Acinetobacter baumannii biofilms in vitro.
Liu, Yannan; Mi, Zhiqiang; Niu, Wenkai; An, Xiaoping; Yuan, Xin; Liu, Huiying; Wang, Yong; Feng, Yuzhong; Huang, Yong; Zhang, Xianglilan; Zhang, Zhiyi; Fan, Hang; Peng, Fan; Li, Puyuan; Tong, Yigang; Bai, Changqing
2016-10-01
The ability of Acinetobacter baumannii to form biofilms and develop antibiotic resistance makes it difficult to control infections caused by this bacterium. In this study, we explored the potential of a lytic bacteriophage to disrupt A. baumannii biofilms. The potential of the lytic bacteriophage to disrupt A. baumannii biofilms was assessed by performing electron microscopy, live/dead bacterial staining, crystal violet staining and by determining adenosine triphosphate release. The bacteriophage inhibited the formation of and disrupted preformed A. baumannii biofilms. Results of disinfection assay showed that the lytic bacteriophage lysed A. baumannii cells suspended in blood or grown on metal surfaces. These results suggest the potential of the lytic bacteriophage to disrupt A. baumannii biofilms.
-
Palmore, Tara N.; Michelin, Angela V.; Bordner, MaryAnn; Odom, Robin T.; Stock, Frida; Sinaii, Ninet; Fedorko, Daniel; Murray, Patrick R.; Henderson, David K.
2016-01-01
Background Multidrug-resistant Acinetobacter baumannii (MDRAB) is difficult to treat and eradicate. Several reports describe isolation and environmental cleaning strategies that controlled hospital MDRAB outbreaks. Such interventions were insufficient to interrupt MDRAB transmission in two intensive care unit-based outbreaks in our hospital. We describe strategies that were associated with termination of MDRAB outbreaks at the NIH Clinical Center. Methods In response to MDRAB outbreaks in 2007 and 2009, we implemented multiple interventions, including stakeholder meetings, enhanced isolation precautions, active microbial surveillance, cohorting, and extensive environmental cleaning. We conducted a case-control study to analyze risk factors for acquiring MDRAB. In each outbreak, infection control adherence monitors were placed in MDRAB cohort areas to observe and correct staff infection control behavior. Results Between May 2007 and December 2009, 63 patients acquired nosocomial MDRAB; 57 (90%) acquired one or more of four outbreak strains. Of 347 environmental cultures, only 2 grew outbreak strains of MDRAB from areas other than MDRAB patient rooms. Adherence monitors recorded 1330 isolation room entries in 2007, of which 8% required interventions. In 2009, around-the-clock monitors recorded 4892 staff observations, including 127 (2.6%) instances of nonadherence with precautions requiring 68 interventions (1.4%). Physicians were responsible for more violations than other staff (58% of hand hygiene violations and 37% of violations relating to gown and glove use). Each outbreak terminated in temporal association with initiation of adherence monitoring. Conclusions Although labor-intensive, adherence monitoring may be useful as part of a multifaceted strategy to limit nosocomial transmission of MDRAB. PMID:22080654
-
Pasanen, Tanja; Koskela, Suvi; Mero, Sointu; Tarkka, Eveliina; Tissari, Päivi; Vaara, Martti; Kirveskari, Juha
2014-01-01
Multidrug-resistant Acinetobacter baumannii (MDRAB) is an increasing problem worldwide. Prevalence of carbapenem resistance in Acinetobacter spp. due to acquired carbapenemase genes is not known in Finland. The purpose of this study was to examine prevalence and clonal spread of multiresistant A. baumannii group species, and their carbapenemase genes. A total of 55 Acinetobacter isolates were evaluated with repetitive PCR (DiversiLab) to analyse clonality of isolates, in conjunction with antimicrobial susceptibility profile for ampicillin/sulbactam, colistin, imipenem, meropenem, rifampicin and tigecycline. In addition, a new real-time PCR assay, detecting most clinically important carbapenemase genes just in two multiplex reactions, was developed. The assay detects genes for KPC, VIM, IMP, GES-1/-10, OXA-48, NDM, GIM-1, SPM-1, IMI/NMC-A, SME, CMY-10, SFC-1, SIM-1, OXA-23-like, OXA-24/40-like, OXA-58 and ISAbaI-OXA-51-like junction, and allows confident detection of isolates harbouring acquired carbapenemase genes. There was a time-dependent, clonal spread of multiresistant A. baumannii strongly correlating with carbapenamase gene profile, at least in this geographically restricted study material. The new carbapenemase screening assay was able to detect all the genes correctly suggesting it might be suitable for epidemiologic screening purposes in clinical laboratories. PMID:24465749
-
Nonaka, Yuko; Nagae, Masaaki; Omae, Takahito; Yamamoto, Shuhei; Horitani, Ryosuke; Maeda, Daigen; Yoshinaga, Takayuki
2014-05-01
A 61-year-old man presented with pain in the abdomen and right lower limb. He had a history of hepatitis B virus-induced liver cirrhosis, but had not been visiting the outpatient clinic and did not receive any medication. Cutaneous necrosis and bulla were observed on his abdomen and right lower limb. The necrotic skin was incised, and he was diagnosed with necrotizing fasciitis. A nonfermentative Gram-negative bacillus infection was confirmed from aspirated fluid and blood cultures. Therefore, meropenem and immunoglobulins were administered. Because necrosis was widespread, surgical debridement was performed. Thereafter, Acinetobacter calcoaceticus infection was confirmed by semi-quantitative PCR using the bullous fluid and blood cultures. Meropenem was administered for 3 weeks, followed by levofloxacin alone for 1 week. The patient's condition improved; therefore, skin grafting was performed as planned and yielded a favorable response. After rehabilitation, the patient could walk without support and infection did not recur. However, he had severe liver cirrhosis and large esophageal varices, and he eventually died from sudden varix rupture. Necrotizing fasciitis is an uncommon soft tissue infection, associated with high morbidity and mortality, and early recognition and treatment are crucial for survival. Acinetobacter is rarely associated with necrotizing fasciitis. Although this is a very rare case of the occurrence of necrotizing fasciitis due to A. calcoaceticus infection, we believe that this organism can be pathogenic in immunocompromised patients such as those with liver cirrhosis by reporting this case. Copyright © 2014 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
-
Zollner-Schwetz, Ines; Zechner, Elisabeth; Ullrich, Elisabeth; Luxner, Josefa; Pux, Christian; Pichler, Gerald; Schippinger, Walter; Krause, Robert; Leitner, Eva
2017-01-01
We aimed to determine the prevalence of colonization by multidrug-resistant Gram-negative bacteria including ESBL-producing enterobacteriaceae, carbapenem-resistant enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii at two wards caring long term for patients with disorder of consciousness at the Geriatric Health Centers Graz, Austria. During our study we detected two A. baumannii outbreaks. In August 2015, we conducted a point-prevalence study. Inguinal and perianal swabs were taken from 38 patients and screened for multidrug-resistant Gram-negative rods using standard procedures. Six months after the initial investigation all patients were sampled again and use of antibiotics during the past 6 months and mortality was registered. Genetic relatedness of bacteria was evaluated by DiversiLab system. Fifty percent of patients were colonized by multidrug-resistant Gram-negative isolates. Five patients harboured ESBL-producing enterobacteriaceae. No carbapenem-resistant enterobacteriaceae were detected. 13/38 patients were colonized by A. baumannii isolates (resistant to ciprofloxacin but susceptible to carbapenems). There was a significant difference in the prevalence of colonization by A. baumannii between ward 2 and ward 1 (60% vs. 5.6%, p < 0.001). Two clusters of A. baumannii isolates were identified including one isolate detected on a chair in a patient's room. We detected a high prevalence of two multidrug-resistant A. baumannii strains in patients with disorder of consciousness at a LTCF in Graz, Austria. Our findings strongly suggest nosocomial cross-transmission between patients. An active surveillance strategy is warranted to avoid missing newly emerging pathogens.
-
Harris, Greg; KuoLee, Rhonda; Chen, Wangxue
2012-01-01
We investigated the ability of compounds interfering with iron metabolism to inhibit the growth of Acinetobacter baumannii. Iron restriction with transferrin or 2,2-bipyridyl significantly inhibited A. baumannii growth in vitro. Gallium nitrate alone was moderately effective at reducing A. baumannii growth but became bacteriostatic in the presence of serum or transferrin. More importantly, gallium nitrate treatment reduced lung bacterial burdens in mice. The use of gallium-based therapies shows promise for the control of multidrug-resistant A. baumannii. PMID:22825117
-
de Léséleuc, Louis; Harris, Greg; KuoLee, Rhonda; Chen, Wangxue
2012-10-01
We investigated the ability of compounds interfering with iron metabolism to inhibit the growth of Acinetobacter baumannii. Iron restriction with transferrin or 2,2-bipyridyl significantly inhibited A. baumannii growth in vitro. Gallium nitrate alone was moderately effective at reducing A. baumannii growth but became bacteriostatic in the presence of serum or transferrin. More importantly, gallium nitrate treatment reduced lung bacterial burdens in mice. The use of gallium-based therapies shows promise for the control of multidrug-resistant A. baumannii.
-
Ahmad, Sajjad; Azam, Syed Sikander
2018-05-05
Acinetobacter baumannii is one of the major cause of nosocomial infections around the globe. The emergence of hyper-virulent strains of the pathogen greatly narrows down therapeutic options for patients infected with this red alert superbug. Development of a peptide-based vaccine can offers an alternative, attractive, and cost-effective remedy for multidrug-resistant A. baumannii associated complications. Herein, we introduced a novel virulome based Reverse Vaccinology for screening peptide based vaccine candidates against A. baumannii and its validation using a negative control. The pipeline screened "FYLNDQPVS" of polysaccharide export outer membrane protein (EpsA) and "LQNNTRRMK" of chaperone-usher pathway protein B (CsuB) as broad-spectrum peptides for induction of targeted immune responses. The 9-mer epitope of both proteins was rendered virulent, antigenic, non-allergen, and highly conserved among thirty-four completely annotated strains. Interactome examination unravels peptides protein direct and indirect interactions with biological significant pathways, essential for A. baumannii pathogenesis and survival. Protein-peptide docking aids in addition by unveiling deep binding of the epitopes in the active site of the most prevalent binding allele in the human population-the DRB1*0101. Both the proteins till to date are not characterized for immunoprotective efficacy and desirable to be deciphered experimentally. The designed series of in silico filters rejected few recently reported peptide and non-peptide vaccine targets and has delivered outcomes, which we believe will enrich the existing knowledge of vaccinology against this life-threatening human pathogen. Copyright © 2018 Elsevier Inc. All rights reserved.
-
Zinc stress induces copper depletion in Acinetobacter baumannii.
Hassan, Karl A; Pederick, Victoria G; Elbourne, Liam D H; Paulsen, Ian T; Paton, James C; McDevitt, Christopher A; Eijkelkamp, Bart A
2017-03-11
The first row transition metal ions zinc and copper are essential to the survival of many organisms, although in excess these ions are associated with significant toxicity. Here, we examined the impact of zinc and copper stress on Acinetobacter baumannii, a common opportunistic pathogen. We show that extracellular zinc stress induces a copper-specific depletion phenotype in A. baumannii ATCC 17978. Supplementation with copper not only fails to rescue this phenotype, but further exacerbates the copper depletion. Extensive analysis of the A. baumannii ATCC 17978 genome identified 13 putative zinc/copper resistance efflux pumps. Transcriptional analyses show that four of these transporters are responsive to zinc stress, five to copper stress and seven to the combination of zinc and copper stress, thereby revealing a likely foundation for the zinc-induced copper starvation in A. baumannii. In addition, we show that zinc and copper play crucial roles in management of oxidative stress and the membrane composition of A. baumannii. Further, we reveal that zinc and copper play distinct roles in macrophage-mediated killing of this pathogen. Collectively, this study supports the targeting of metal ion homeostatic mechanisms as an effective antimicrobial strategy against multi-drug resistant bacterial pathogens.
-
Antunes, Luísa C S; Imperi, Francesco; Minandri, Fabrizia; Visca, Paolo
2012-11-01
Multidrug-resistant Acinetobacter baumannii poses a tremendous challenge to traditional antibiotic therapy. Due to the crucial role of iron in bacterial physiology and pathogenicity, we investigated iron metabolism as a possible target for anti-A. baumannii chemotherapy using gallium as an iron mimetic. Due to chemical similarity, gallium competes with iron for binding to several redox enzymes, thereby interfering with a number of essential biological reactions. We found that Ga(NO(3))(3), the active component of an FDA-approved drug (Ganite), inhibits the growth of a collection of 58 A. baumannii strains in both chemically defined medium and human serum, at concentrations ranging from 2 to 80 μM and from 4 to 64 μM, respectively. Ga(NO(3))(3) delayed the entry of A. baumannii into the exponential phase and drastically reduced bacterial growth rates. Ga(NO(3))(3) activity was strongly dependent on iron availability in the culture medium, though the mechanism of growth inhibition was independent of dysregulation of gene expression controlled by the ferric uptake regulator Fur. Ga(NO(3))(3) also protected Galleria mellonella larvae from lethal A. baumannii infection, with survival rates of ≥75%. At therapeutic concentrations for humans (28 μM plasma levels), Ga(NO(3))(3) inhibited the growth in human serum of 76% of the multidrug-resistant A. baumannii isolates tested by ≥90%, raising expectations on the therapeutic potential of gallium for the treatment of A. baumannii bloodstream infections. Ga(NO(3))(3) also showed strong synergism with colistin, suggesting that a colistin-gallium combination holds promise as a last-resort therapy for infections caused by pan-resistant A. baumannii.
-
Antunes, Luísa C. S.; Imperi, Francesco; Minandri, Fabrizia
2012-01-01
Multidrug-resistant Acinetobacter baumannii poses a tremendous challenge to traditional antibiotic therapy. Due to the crucial role of iron in bacterial physiology and pathogenicity, we investigated iron metabolism as a possible target for anti-A. baumannii chemotherapy using gallium as an iron mimetic. Due to chemical similarity, gallium competes with iron for binding to several redox enzymes, thereby interfering with a number of essential biological reactions. We found that Ga(NO3)3, the active component of an FDA-approved drug (Ganite), inhibits the growth of a collection of 58 A. baumannii strains in both chemically defined medium and human serum, at concentrations ranging from 2 to 80 μM and from 4 to 64 μM, respectively. Ga(NO3)3 delayed the entry of A. baumannii into the exponential phase and drastically reduced bacterial growth rates. Ga(NO3)3 activity was strongly dependent on iron availability in the culture medium, though the mechanism of growth inhibition was independent of dysregulation of gene expression controlled by the ferric uptake regulator Fur. Ga(NO3)3 also protected Galleria mellonella larvae from lethal A. baumannii infection, with survival rates of ≥75%. At therapeutic concentrations for humans (28 μM plasma levels), Ga(NO3)3 inhibited the growth in human serum of 76% of the multidrug-resistant A. baumannii isolates tested by ≥90%, raising expectations on the therapeutic potential of gallium for the treatment of A. baumannii bloodstream infections. Ga(NO3)3 also showed strong synergism with colistin, suggesting that a colistin-gallium combination holds promise as a last-resort therapy for infections caused by pan-resistant A. baumannii. PMID:22964249
-
Stress Response and Virulence Functions of the Acinetobacter baumannii NfuA Fe-S Scaffold Protein
Zimbler, Daniel L.; Park, Thomas M.; Arivett, Brock A.; Penwell, William F.; Greer, Samuel M.; Woodruff, Tessa M.; Tierney, David L.
2012-01-01
To successfully establish an infection, Acinetobacter baumannii must overcome the iron starvation and oxidative stress imposed by the human host. Although previous studies have shown that ATCC 19606T cells acquire iron via the acinetobactin-mediated siderophore system, little is known about intracellular iron metabolism and its relation to oxidative stress in this pathogen. Screening of an insertion library resulted in the isolation of the ATCC 19606T derivative 1644, which was unable to grow in iron-chelated media. Rescue cloning and DNA sequencing showed that the insertion inactivated a gene coding for an NfuA Fe-S cluster protein ortholog, without any effect on the expression of the acinetobactin system. The nfuA mutant was also more sensitive to hydrogen peroxide and cumene hydroperoxide than the parental strain. The iron chelation- and oxidative-stress-deficient responses of this mutant were corrected when complemented with either the ATCC 19606T parental allele or the Escherichia coli MG1655 nfuA ortholog. Furthermore, electron paramagnetic resonance (EPR) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analyses showed that the ATCC 19606T NfuA ortholog has iron-binding properties compatible with the formation of [Fe-S] cluster protein. Ex vivo and in vivo assays using human epithelial cells and Galleria mellonella, respectively, showed that NfuA is critical for bacterial growth independent of their capacity to acquire iron or the presence of excess of free iron. Taken together, these observations indicate that the A. baumannii NfuA ortholog plays a role in intracellular iron utilization and protection from oxidative-stress responses that this pathogen could encounter during the infection of the human host. PMID:22467784
-
Araújo, B C; Moraes, M S; Costa, L E O; Nascimento, J S
2015-04-01
Infant milk formulas are not sterile products, and pathogenic bacteria can survive and multiply in these products. This study was performed, initially, to detect the presence of Salmonella spp. in reconstituted infant milk formula and on utensils previously sanitized used in their preparation or distribution in a nursery of a public hospital in Rio de Janeiro. None of the samples tested carried Salmonellaspp. However, further identification of colonies growing on the selective media revealed the presence of several other gram-negative bacteria. Seventeen isolates were identified as belonging to Acinetobacter baumannii-calcoaceticus complex. Fourteen isolates presented a multidrug-resistance profile, by disc diffusion assays, and one of them--JE4--was also resistant to imipenem. The detection of Acinetobacter isolates in this work demonstrates inadequate hygiene practices in the preparation or distribution of infant milk formula. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
-
Choudhary, D. K.
2011-01-01
Despite evaluation of large number of agroindustrial wastes for their use as casing material for Agaricus bisporus (Lange) Imbach cultivation, scant attention has been given to the importance of biological properties of casing materials. In the present study, an attempt was made to characterize the bacterial flora in casing layer, namely, Farm Yard Manure (FYM) and Spent Mushroom Substrate/spent compost (SMS/SC) (FYM+SC, 3 : 1) and FYM and Vermi Compost (VC) (FYM+VC, 3 : 1), employing partial 16S rDNA sequencing. Available data showed a significant variety of organisms that included Acinetobacter and Pseudomonas of the γ-proteobacteria, that were the most frequently encountered genera. This is the first preliminary report on the microbial diversity of casing soils and demonstrates the presence of Acinetobacter spp. that has not been previously described in casing material. PMID:22007222
-
Digestion of rice straw and oil palm fronds by microflora from rumen and termite bacteria, in vitro.
Ramin, M; Alimon, A R; Panandam, J M; Sijam, K; Javanmard, A; Abdullah, N
2008-02-15
The digestion and Volatile Fatty Acid (VFA) production from rice straw and oil palm fronds by cellulolytic bacteria isolated from the termite Coptotermes curvignathus were investigated. The bacteria were Acinetobacter strain Raminalimon, Enterobacter aerogenes strain Razmin C, Enterobacter cloacae strain Razmin B, Bacillus cereus strain Razmin A and Chryseobacterium kwangyangense strain Cb. Acinetobacter strain Raminalimon is an aerobic bacterium, while the other species are facultative anaerobes. There were significant differences (p<0.05) among the bacteria for Dry Matter (DM) lost and acetic acid production from rice straw and Acinetobacter strain Raminalimon showed the highest activity. The facultative bacteria C. kwangyangense strain Cb (cfu mL(-1) 231 x 10(-6), OD: 0.5), E. cloacae (cfu mL(-1) 68 x 10(-7), OD: 0.5) and E. aerogenes (cfu mL(-1) 33 x 10(-7), OD: 0.5) were used for digestion study with the rumen fluid microflora. The in vitro gas production technique was applied for the comparative study and the parameters measured were pH, gas (volume), dry matter lost, acetic acid, propionic acid and butyric acid concentrations. pH was not significantly (p<0.05) different among the five treatments. The bacterium C. kwangyangense strain Cb showed the highest activity (p<0.05) for DM lost, acetic acid, propionic acid and butyric acid production from rice straw when compared to the other bacterial activities. There was no significance (p<0.05) difference between the three bacteria for the dry matter lost of oil palm fronds but the production of Volatile Fatty Acids (VFA) was significantly (p<0.05) high in the treatment which was inoculated with C. kwangyangense strain Cb. The Gen Bank NCBI/EMBL accession numbers for the bacterial strains are EU332791, EU305608, EU305609, EU294508 and EU169201.
-
Mathlouthi, Najla; El Salabi, Allaaeddin Ali; Ben Jomàa-Jemili, Mariem; Bakour, Sofiane; Al-Bayssari, Charbel; Zorgani, Abdulaziz A; Kraiema, Abdulmajeed; Elahmer, Omar; Okdah, Liliane; Rolain, Jean-Marc; Chouchani, Chedly
2016-07-01
Acinetobacter baumannii is an opportunistic pathogen causing various nosocomial infections. The aim of this study was to characterise the molecular support of carbapenem-resistant A. baumannii clinical isolates recovered from two Libyan hospitals. Bacterial isolates were identified by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Antibiotic susceptibility testing was performed using disk diffusion and Etest methods, and carbapenem resistance determinants were studied by PCR amplification and sequencing. Multilocus sequence typing (MLST) was performed for typing of the isolates. All 36 imipenem-resistant isolates tested were identified as A. baumannii. The blaOXA-23 gene was detected in 29 strains (80.6%). The metallo-β-lactamase blaNDM-1 gene was detected in eight isolates (22.2%), showing dissemination of multidrug-resistant (MDR) A. baumannii in Tripoli Medical Center and Burn and Plastic Surgery Hospital in Libya, including one isolate that co-expressed the blaOXA-23 gene. MLST revealed several sequence types (STs). Imipenem-resistant A. baumannii ST2 was the predominant clone (16/36; 44.4%). This study shows that NDM-1 and OXA-23 contribute to antibiotic resistance in Libyan hospitals and represents the first incidence of the association of these two carbapenemases in an autochthonous MDR A. baumannii isolated from patients in Libya, indicating that there is a longstanding infection control problem in these hospitals. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.
-
Chitosan as an effective inhibitor of multidrug resistant Acinetobacter baumannii.
Costa, E M; Silva, S; Vicente, S; Veiga, M; Tavaria, F; Pintado, M M
2017-12-15
Over the last two decades worldwide levels of antibiotic resistance have risen leading to the appearance of multidrug resistant microorganisms. Acinetobacter baumannii is a known skin pathogen which has emerged as a major cause of nosocomial outbreaks due to its capacity to colonize indwelling medical devices and natural antibiotic resistance. With chitosan being an effective antimicrobial agent against antibiotic resistant microorganisms, the aim of this work was to access its potential as an alternative to traditional antimicrobials in the management of A. baumannii growth. What the results showed was that both chitosan MW's tested were active upon A. baumannii's planktonic and sessile growth. For planktonic growth MICs and MBCs were obtained at relatively low concentrations (0.5-2mg/mL) while for sessile growth chitosan proved to be an effective inhibitor of A. baumannii's adhesion and biofilm formation. Considering these results chitosan shows a high potential for control of A. baumannii infections. Copyright © 2017 Elsevier Ltd. All rights reserved.
-
Sutton, Kristin A; Breen, Jennifer; MacDonald, Ulrike; Beanan, Janet M; Olson, Ruth; Russo, Thomas A; Schultz, L Wayne; Umland, Timothy C
2015-08-01
Acinetobacter baumannii is an opportunistic Gram-negative pathogen that is an important cause of healthcare-associated infections exhibiting high mortality rates. Clinical isolates of multidrug-resistant (MDR) and extremely drug-resistant (XDR) A. baumannii strains are increasingly being observed. Compounding this concern is the dearth of new antibacterial agents in late-stage development that are effective against MDR and XDR A. baumannii. As part of an effort to address these concerns, two genes (aroA and aroC) of the shikimate pathway have previously been determined to be essential for the growth and survival of A. baumannii during host infection (i.e. to be essential in vivo). This study expands upon these results by demonstrating that the A. baumannii aroK gene, encoding shikimate kinase (SK), is also essential in vivo in a rat soft-tissue infection model. The crystal structure of A. baumannii SK in complex with the substrate shikimate and a sulfate ion that mimics the binding interactions expected for the β-phosphate of ATP was then determined to 1.91 Å resolution and the enzyme kinetics were characterized. The flexible shikimate-binding domain and LID region are compared with the analogous regions in other SK crystal structures. The impact of structural differences and sequence divergence between SKs from pathogenic bacteria that may influence antibiotic-development efforts is discussed.
-
Hwang, Yoon Y; Ramalingam, Karthikeyan; Bienek, Diane R; Lee, Valerie; You, Tao; Alvarez, Rene
2013-08-01
Acinetobacter baumannii has emerged as a serious problematic pathogen due to the ever-increasing presence of antibiotic resistance, demonstrating a need for novel, broad-spectrum antimicrobial therapeutic options. Antimicrobial nanoemulsions are emulsified mixtures of detergent, oil, and water (droplet size, 100 to 800 nm) which have broad antimicrobial activity against bacteria, enveloped viruses, and fungi. Here, we screened the antimicrobial activities of five nanoemulsion preparations against four Acinetobacter baumannii isolates to identify the most suitable preparation for further evaluation. Among them, N5, which contains 10% (vol/vol) Triton X-100, 25% (vol/vol) soybean oil, and 1% (wt/vol) cetylpyridinium chloride (CPC), showed the best efficacy against A. baumannii in both its planktonic and biofilm forms and was selected for further study. Our data demonstrate that, while the killing of planktonic forms of A. baumannii was due to the 1% CPC component of our nanoemulsions, the breakdown of biofilms was achieved via the emulsified oil and detergent fractions. Furthermore, we documented the effect of ethanol and NaCl in combination with N5 on planktonic A. baumannii. In killing curves of N5 combined with other agents (ethanol or NaCl), a synergistic effect of a ≥ 2-log decrease in CFU/ml was observed. The antibiofilm activity of N5 was confirmed via a cell proliferation test and scanning electron microscopy. The effects of exposure to severe environmental conditions, which simulates the field conditions in Iraq and Afghanistan, were evaluated, and this exposure did not affect the overall antimicrobial activity of N5. These studies lay a solid foundation for the utilization of nanoemulsions against the antibiotic-resistant forms of A. baumannii.
-
Hwang, Yoon Y.; Ramalingam, Karthikeyan; Bienek, Diane R.; Lee, Valerie; You, Tao
2013-01-01
Acinetobacter baumannii has emerged as a serious problematic pathogen due to the ever-increasing presence of antibiotic resistance, demonstrating a need for novel, broad-spectrum antimicrobial therapeutic options. Antimicrobial nanoemulsions are emulsified mixtures of detergent, oil, and water (droplet size, 100 to 800 nm) which have broad antimicrobial activity against bacteria, enveloped viruses, and fungi. Here, we screened the antimicrobial activities of five nanoemulsion preparations against four Acinetobacter baumannii isolates to identify the most suitable preparation for further evaluation. Among them, N5, which contains 10% (vol/vol) Triton X-100, 25% (vol/vol) soybean oil, and 1% (wt/vol) cetylpyridinium chloride (CPC), showed the best efficacy against A. baumannii in both its planktonic and biofilm forms and was selected for further study. Our data demonstrate that, while the killing of planktonic forms of A. baumannii was due to the 1% CPC component of our nanoemulsions, the breakdown of biofilms was achieved via the emulsified oil and detergent fractions. Furthermore, we documented the effect of ethanol and NaCl in combination with N5 on planktonic A. baumannii. In killing curves of N5 combined with other agents (ethanol or NaCl), a synergistic effect of a ≥2-log decrease in CFU/ml was observed. The antibiofilm activity of N5 was confirmed via a cell proliferation test and scanning electron microscopy. The effects of exposure to severe environmental conditions, which simulates the field conditions in Iraq and Afghanistan, were evaluated, and this exposure did not affect the overall antimicrobial activity of N5. These studies lay a solid foundation for the utilization of nanoemulsions against the antibiotic-resistant forms of A. baumannii. PMID:23669390
-
Mirshekar, Maryam; Shahcheraghi, Fereshteh; Azizi, Omid; Solgi, Hamid; Badmasti, Farzad
2018-05-01
Acinetobacter baumannii is an important nosocomial pathogen which causes a wide range of infections. In this study, we addressed the role of class 1 integron, ISAba1 and ISAba125 associated with antimicrobial resistance in 72 clinical isolates of A. baumannii collected from clinical settings in Tehran, Iran. Moreover, to study the clonal relatedness of strains, repetitive extragenic palindromic-PCR (rep-PCR) assay was carried out. PCR revealed that bla OXA-51 -like, bla OXA-23 -like, bla OXA-24/40 -like, bla OXA-58 -like, bla NDM , integrase gene (intI1), ISAba1, and ISAba125 were present in 86.11% (62/72), 84.72% (61/72), 30.55% (22/72), 0% (0/72), 0% (0/72), 58.33% (42/72), 97.22% (70/72), and 65.27% (47/72) of the strains, respectively. Sequencing of 39 internal variable regions of class 1 integrons showed seven gene cassette arrays, including aadA4-catB8-aadA1 (2.77%), aadA1-aadA4 (1.38%), aacC4-aadA1 (2.77%), aacC4 (22.22%), aadA1 (13.88%), aadA4 (5.55%), and catB8 (5.55%). We detected ISAba1 in the upstream of bla OXA-23 -like, bla OXA-51 -like, and bla ADC in 54.16% (39/72), 9.72% (7/72), and 56.94% (41/72) of the strains, respectively. Whereas, there was a low frequency of disruptions in carO and dacD genes: 5.55% (4/72) and 4.16% (3/72). Rep-PCR analysis revealed that the isolates were genetically diverse. However, Cl-12 and Cl-15 were the largest clusters and they were recovered from various hospitals. Our analysis showed the high rates of class 1 integrons as a repertoire of aminoglycoside-modifying enzymes. It seems that linkages of ISAba1-bla OXA-23 -like and ISAba1-bla OXA-69 , and disruptions in carO or dacD can develop resistance to carbapenems among clinical isolates of A. baumannii.
-
Fijen, C A; Kuijper, E J; Tjia, H G; Daha, M R; Dankert, J
1994-05-01
Nongroupable meningococci or bacteria related to the genus Neisseria rarely cause meningitis. Complement deficiency has been identified as a major predisposing factor for meningococcal disease. To assess whether patients with meningitis due to such strains have a complement deficiency, we studied 12 persons. Six patients had meningitis due to nongroupable strains of meningococci, and six patients had meningitis due to Moraxella species or Acinetobacter species. Inherited complement component C7 or C8 deficiency was found in two persons who had had meningitis due to nongroupable meningococci, and one C8-deficient person had had meningitis caused by Moraxella osloensis. Hypocomplementemia resulting from CSF drain-associated shunt nephritis was found in one person with meningitis due to Moraxella nonliquefaciens and in one person with meningitis due to Acinetobacter lwoffi. This rather high frequency of inherited or acquired complement deficiencies among patients with meningitis due to nongroupable meningococci, Moraxella species, and Acinetobacter species justifies the recommendation that such patients must be studied for complement deficiency.
-
Lean, Soo-Sum; Yeo, Chew Chieng; Suhaili, Zarizal; Thong, Kwai-Lin
2015-01-01
Acinetobacter baumannii is a Gram-negative nosocomial pathogen of importance due to its uncanny ability to acquire resistance to most antimicrobials. These include carbapenems, which are the drugs of choice for treating A. baumannii infections, and polymyxins, the drugs of last resort. Whole genome sequencing was performed on two clinical carbapenem-resistant A. baumannii AC29 and AC30 strains which had an indistinguishable ApaI pulsotype but different susceptibilities to polymyxin. Both genomes consisted of an approximately 3.8 Mbp circular chromosome each and several plasmids. AC29 (susceptible to polymyxin) and AC30 (resistant to polymyxin) belonged to the ST195 lineage and are phylogenetically clustered under the International Clone II (IC-II) group. An AbaR4-type resistance island (RI) interrupted the comM gene in the chromosomes of both strains and contained the bla OXA-23 carbapenemase gene and determinants for tetracycline and streptomycin resistance. AC29 harbored another copy of bla OXA-23 in a large (~74 kb) conjugative plasmid, pAC29b, but this gene was absent in a similar plasmid (pAC30c) found in AC30. A 7 kb Tn1548::armA RI which encodes determinants for aminoglycoside and macrolide resistance, is chromosomally-located in AC29 but found in a 16 kb plasmid in AC30, pAC30b. Analysis of known determinants for polymyxin resistance in AC30 showed mutations in the pmrA gene encoding the response regulator of the two-component pmrAB signal transduction system as well as in the lpxD, lpxC, and lpsB genes that encode enzymes involved in the biosynthesis of lipopolysaccharide (LPS). Experimental evidence indicated that impairment of LPS along with overexpression of pmrAB may have contributed to the development of polymyxin resistance in AC30. Cloning of a novel variant of the bla AmpC gene from AC29 and AC30, and its subsequent expression in E. coli also indicated its likely function as an extended-spectrum cephalosporinase.
-
Hansen, Frank; Hammerum, Anette M; Skov, Robert; Haldorsen, Bjørg; Sundsfjord, Arnfinn; Samuelsen, Orjan
2014-08-01
Phenotypic tests for carbapenemase production in Pseudomonas aeruginosa and Acinetobacter baumannii have been associated with unspecific metallo-β-lactamase (MBL) inhibitor activity in synergy tests and low positive predictive value. In this study, a collection of well-characterized P. aeruginosa and A. baumannii isolates was used to evaluate the inhibitor-based Total MBL Confirm Kit and the MBL Etest. Copyright © 2014 Elsevier Inc. All rights reserved.
-
Bioluminescence-based system for rapid detection of natural transformation.
Santala, Ville; Karp, Matti; Santala, Suvi
2016-07-01
Horizontal gene transfer plays a significant role in bacterial evolution and has major clinical importance. Thus, it is vital to understand the mechanisms and kinetics of genetic transformations. Natural transformation is the driving mechanism for horizontal gene transfer in diverse genera of bacteria. Our study introduces a simple and rapid method for the investigation of natural transformation. This highly sensitive system allows the detection of a transformation event directly from a bacterial population without any separation step or selection of cells. The system is based on the bacterial luciferase operon from Photorhabdus luminescens The studied molecular tools consist of the functional modules luxCDE and luxAB, which involve a replicative plasmid and an integrative gene cassette. A well-established host for bacterial genetic investigations, Acinetobacter baylyi ADP1, is used as the model bacterium. We show that natural transformation followed by homologous recombination or plasmid recircularization can be readily detected in both actively growing and static biofilm-like cultures, including very rare transformation events. The system allows the detection of natural transformation within 1 h of introducing sample DNA into the culture. The introduced method provides a convenient means to study the kinetics of natural transformation under variable conditions and perturbations. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
-
Iqbal, Aneela; Arshad, Muhammad; Hashmi, Imran; Karthikeyan, Raghupathy; Gentry, Terry J; Schwab, Arthur Paul
2017-06-13
The presence of benzene and phenol in the environment can lead to serious health effects in humans and warrant development of efficient cleanup strategies. The aim of the present work was to assess the potential of indigenous endophytic bacterial strains to degrade benzene and phenol. Seven strains were successfully isolated from Cannabis sativa plants irrigated with oil refinery wastewater. Molecular characterization was performed by 16S rRNA gene sequencing. Phenol was biodegraded almost completely with Achromobacter sp. (AIEB-7), Pseudomonas sp. (AIEB-4), and Alcaligenes sp. (AIEB-6) at 250, 500, and 750 mg L -1 ; however, the degradation was only 81%, 72%, and 69%, respectively, when exposed to 1000 mg L -1 . Bacillus sp. (AIEB-1), Enterobacter sp. (AIEB-3), and Acinetobacter sp. (AIEB-2) degraded benzene significantly at 250, 500, and 750 mg L -1 . However, these strains showed 80%, 72%, and 68% benzene removal at 1000 mg L -1 exposure, respectively. Rates of degradation could be modeled with first-order kinetics with rate constant values of 1.86 × 10 -2 for Pseudomonas sp. (AIEB-4) and 1.80 × 10 -2 h -1 for Bacillus sp. (AIEB-1) and half-lives of 1.5 and 1.6 days, respectively. These results establish a foundation for further testing of the phytoremediation of hydrocarbon-contaminated soils in the presence of these endophytic bacteria.
-
Guzek, A; Korzeniewski, K; Tomaszewski, D; Rybicki, Z; Zwolińska, E
2017-01-01
The article presents the results of 11-year study (2005-2015) of Gram-negative bacteria responsible for pneumonia in 2033 mechanically ventilated patients hospitalized in Intensive Care Unit. Of 8796 biological samples, consisting mainly of bronchial aspirate (97.9 %), 2056 bacterial strains were isolated and subjected to identification. VITEK 2 was used to determine drug susceptibility (classified according to the EUCAST criteria). ESBL, MBL and KPC-producing strains were identified by means of phenotypic methods using appropriate discs. The findings were that the predominant bacteria responsible for infections consisted of Enterobacteriaceae (42.0 %), Acinetobacter baumannii (37.2 %), Pseudomonas aeruginosa (16.1 %), and Stenotrophomonas maltophila (4.7 %). We observed a rise in the number of bacteria causing pneumonia throughout the study period, especially in S. maltophila and Enterobacteriaceae ESBL (+). Gram-negative bacilli were 100 % susceptible to colistin, apart from naturally resistant strains such as Proteus mirabilis, Serratia marcescens, whereas Enterobacteriaceae ESBL (+) were susceptible to imipenem and meropenem. Acinetobacter baumannii strains exhibited the lowest drug susceptibility. In conclusion, we report an increase in the prevalence of pneumonia associated with Gram-negative bacteria in mechanically ventilated intensive care patients. Colistin remains the most effective drug against the majority of Gram-negative bacteria. Therapeutic problems are common in the course of treatment of Acinetobacter baumannii infections.
-
Cameranesi, María M.; Morán-Barrio, Jorgelina; Limansky, Adriana S.; Repizo, Guillermo D.; Viale, Alejandro M.
2018-01-01
Members of the genus Acinetobacter possess distinct plasmid types which provide effective platforms for the acquisition, evolution, and dissemination of antimicrobial resistance structures. Many plasmid-borne resistance structures are bordered by short DNA sequences providing potential recognition sites for the host XerC and XerD site-specific tyrosine recombinases (XerC/D-like sites). However, whether these sites are active in recombination and how they assist the mobilization of associated resistance structures is still poorly understood. Here we characterized the plasmids carried by Acinetobacter baumannii Ab242, a multidrug-resistant clinical strain belonging to the ST104 (Oxford scheme) which produces an OXA-58 carbapenem-hydrolyzing class-D β-lactamase (CHDL). Plasmid sequencing and characterization of replication, stability, and adaptive modules revealed the presence in Ab242 of three novel plasmids lacking self-transferability functions which were designated pAb242_9, pAb242_12, and pAb242_25, respectively. Among them, only pAb242_25 was found to carry an adaptive module encompassing an ISAba825-blaOXA-58 arrangement accompanied by a TnaphA6 transposon, the whole structure conferring simultaneous resistance to carbapenems and aminoglycosides. Ab242 plasmids harbor several XerC/D-like sites, with most sites found in pAb242_25 located in the vicinity or within the adaptive module described above. Electrotransformation of susceptible A. nosocomialis cells with Ab242 plasmids followed by imipenem selection indicated that the transforming plasmid form was a co-integrate resulting from the fusion of pAb242_25 and pAb242_12. Further characterization by cloning and sequencing studies indicated that a XerC/D site in pAb242_25 and another in pAb242_12 provided the active sister pair for the inter-molecular site-specific recombination reaction mediating the fusion of these two plasmids. Moreover, the resulting co-integrate was found also to undergo intra
-
DOE Office of Scientific and Technical Information (OSTI.GOV)
Firstenberg-Eden, R.; Rowley, D.B.; Shattuck, G.E.
1980-09-01
The effect of various stages of the irradiation processing of beef on the injury and inactivation of radiation-resistant Moraxella-Acinetobactor cells was studied. Moraxella-Acinetobacter cells were more resistant to heat inactivation and injury when heated in meat with salts (0.75% NaCl and 0.375% sodium tripolyphosphate) than in meat without salts. These salts had no effect on radiation resistance. Heated cells were more sensitive to radiation inactivation and injury than unheated cells. After repair, the cells regained their resistance to both NaCl and irradiation. Freezing and storage at -40/sup 0/C for 14 days had only a slight effect on either unstressed ormore » heat-stressed cells.« less
-
Rapid identification of ESKAPE bacterial strains using an autonomous microfluidic device.
Ho, Jack Y; Cira, Nate J; Crooks, John A; Baeza, Josue; Weibel, Douglas B
2012-01-01
This article describes Bacteria ID Chips ('BacChips'): an inexpensive, portable, and autonomous microfluidic platform for identifying pathogenic strains of bacteria. BacChips consist of a set of microchambers and channels molded in the elastomeric polymer, poly(dimethylsiloxane) (PDMS). Each microchamber is preloaded with mono-, di-, or trisaccharides and dried. Pressing the layer of PDMS into contact with a glass coverslip forms the device; the footprint of the device in this article is ∼6 cm(2). After assembly, BacChips are degased under large negative pressure and are stored in vacuum-sealed plastic bags. To use the device, the bag is opened, a sample containing bacteria is introduced at the inlet of the device, and the degased PDMS draws the sample into the central channel and chambers. After the liquid at the inlet is consumed, air is drawn into the BacChip via the inlet and provides a physical barrier that separates the liquid samples in adjacent microchambers. A pH indicator is admixed with the samples prior to their loading, enabling the metabolism of the dissolved saccharides in the microchambers to be visualized. Importantly, BacChips operate without external equipment or instruments. By visually detecting the growth of bacteria using ambient light after ∼4 h, we demonstrate that BacChips with ten microchambers containing different saccharides can reproducibly detect the ESKAPE panel of pathogens, including strains of: Enterococcus faecalis, Enteroccocus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter aerogenes, and Enterobacter cloacae. This article describes a BacChip for point-of-care detection of ESKAPE pathogens and a starting point for designing multiplexed assays that identify bacterial strains from clinical samples and simultaneously determine their susceptibility to antibiotics.
-
Rapid Identification of ESKAPE Bacterial Strains Using an Autonomous Microfluidic Device
Ho, Jack Y.; Cira, Nate J.; Crooks, John A.; Baeza, Josue; Weibel, Douglas B.
2012-01-01
This article describes Bacteria ID Chips (‘BacChips’): an inexpensive, portable, and autonomous microfluidic platform for identifying pathogenic strains of bacteria. BacChips consist of a set of microchambers and channels molded in the elastomeric polymer, poly(dimethylsiloxane) (PDMS). Each microchamber is preloaded with mono-, di-, or trisaccharides and dried. Pressing the layer of PDMS into contact with a glass coverslip forms the device; the footprint of the device in this article is ∼6 cm2. After assembly, BacChips are degased under large negative pressure and are stored in vacuum-sealed plastic bags. To use the device, the bag is opened, a sample containing bacteria is introduced at the inlet of the device, and the degased PDMS draws the sample into the central channel and chambers. After the liquid at the inlet is consumed, air is drawn into the BacChip via the inlet and provides a physical barrier that separates the liquid samples in adjacent microchambers. A pH indicator is admixed with the samples prior to their loading, enabling the metabolism of the dissolved saccharides in the microchambers to be visualized. Importantly, BacChips operate without external equipment or instruments. By visually detecting the growth of bacteria using ambient light after ∼4 h, we demonstrate that BacChips with ten microchambers containing different saccharides can reproducibly detect the ESKAPE panel of pathogens, including strains of: Enterococcus faecalis, Enteroccocus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter aerogenes, and Enterobacter cloacae. This article describes a BacChip for point-of-care detection of ESKAPE pathogens and a starting point for designing multiplexed assays that identify bacterial strains from clinical samples and simultaneously determine their susceptibility to antibiotics. PMID:22848451
-
Multidrug-resistant organisms in military wounds from Iraq and Afghanistan.
Calhoun, Jason H; Murray, Clinton K; Manring, M M
2008-06-01
Mortality from battlefield wounds has historically declined, thanks to better surgical management, faster transport of casualties, and improved antibiotics. Today, one of the major challenges facing U.S. military caregivers is the presence of multidrug-resistant organisms in orthopaedic extremity wounds. The most frequently identified resistant strains of bacteria are Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter calcoaceticus-baumannii complex. Overuse of broad-spectrum antibiotics may be an important factor in building resistant strains. Acinetobacter infections appear to hospital-acquired and not from an initial colonization of the injury. More research is required to give military physicians the tools they require to reduce the infection rate and defeat multidrug-resistant organisms.
-
Mnif, Inès; Mnif, Sami; Sahnoun, Rihab; Maktouf, Sameh; Ayedi, Younes; Ellouze-Chaabouni, Semia; Ghribi, Dhouha
2015-10-01
Bioremediation, involving the use of microorganisms to detoxify or remove pollutants, is the most interesting strategy for hydrocarbon remediation. In this aim, four hydrocarbon-degrading bacteria were isolated from oil-contaminated soil in Tunisia. They were identified by the 16S rDNA sequence analysis, as Lysinibacillus bronitolerans RI18 (KF964487), Bacillus thuringiensis RI16 (KM111604), Bacillus weihenstephanensis RI12 (KM094930), and Acinetobacter radioresistens RI7 (KJ829530). Moreover, a lipopeptide biosurfactant produced by Bacillus subtilis SPB1, confirmed to increase diesel solubility, was tested to increase diesel biodegradation along with co-inoculation with two biosurfactant-producing strains. Culture studies revealed the enhancement of diesel biodegradation by the selected consortium with the addition of SPB1 lipopeptide and in the cases of co-inoculation by biosurfactant-producing strain. In fact, an improvement of about 38.42 and 49.65 % of diesel degradation was registered in the presence of 0.1 % lipopeptide biosurfactant and when culturing B. subtilis SPB1 strain with the isolated consortium, respectively. Furthermore, the best improvement, evaluated to about 55.4 %, was recorded when using the consortium cultured with B. subtilis SPB1 and A. radioresistens RI7 strains. Gas chromatography analyses were correlated with the gravimetric evaluation of the residual hydrocarbons. Results suggested the potential applicability of the selected consortium along with the ex situ- and in situ-added biosurfactant for the effective bioremediation of diesel-contaminated water and soil.
-
Aşik, Gülşah; Özdemir, Mehmet; Kurtoğlu, Muhammet Güzel; Yağci, Server; Öksüz, Lütfiye; Gül, Mustafa; Koçoğlu, Mücahide Esra; Sesli Çetin, Emel; Seyrek, Adnan; Berktaş, Mustafa; Ayyildiz, Ahmet; Çiftci, İhsan Hakkı
2014-01-01
β-Lactamases are an important resistance mechanism in Acinetobacter baumannii. Pseudomonas extended-resistance (PER-1) type β-lactamase-producing strains have been reported from various geographic locations; however, PER-1 type β-lactamases from Turkish hospitals have not been investigated extensively. The aim of this study was to determine the prevalence of PER-1 type β-lactamases in A. baumannii isolates in various regions of Turkey. A total of 763 clinical A. baumannii isolates were collected from 9 university hospitals and 2 state hospitals between 2008 and 2011. Molecular amplification of the OXA-51 gene from the A. baumannii genome was performed in order to verify identification of the species. Real-time polymerase chain reaction was used to detect blaPER-1 genes. PER-1 was detected in 24.6% of the isolates. The annual frequencies of the PER-1 enzyme were detected as 52.2%, 35.9%, and 8.3% in 2008, 2009, and 2010, respectively. PER-1 prevalence decreased gradually over time. The differences observed in PER-1 prevalence among the regions of Turkey were statistically significant (chi-square test; P < 0.001). These data demonstrate that the frequency of detection of PER-1 type β-lactamases in A. baumannii species has decreased in Turkey. However, the increased carbapenem resistance, together with multidrug resistance, has created a worrisome situation regarding this pathogen.
-
Zhang, Dayi; Ding, Aizhong; Cui, Shuangchao; Hu, Cheng; Thornton, Steven F; Dou, Junfeng; Sun, Yujiao; Huang, Wei E
2013-03-01
Accidents involving the release of crude oil to seawater pose serious threat to human and animal health, fisheries and marine ecosystems. A whole cell bioreporter detection method, which has unique advantages for the rapid evaluation on toxicity and bioavailability, is a useful tool to provide environmental risk assessments at crude oil-contaminated sites. Acinetobacter baylyi ADPWH_alk and ADPWH_recA are chromosomally-based alkane and genotoxicity bioreporters which can be activated to express bioluminescence in the presence of alkanes and genotoxic compounds. In this study, we applied Acinetobacter ADPWH_alk and ADPWH_recA bioreporters to examine six seawater and six sediment samples around the Dalian Bay four weeks after an oil tank explosion in Dalian, China in 2010, and compared the results with samples from the same sites one year after. The results of bioreporter detection suggest that seawater and sediments from five sites (DB, NT, JSB, XHP and FJZ) four weeks after the oil-spill were contaminated by the crude oil with various extents of genotoxicity. Among these six sites, DB and NT had high oil contents and genotoxicity, and JSB had high oil content but low genotoxicity in comparison with an uncontaminated site LSF, which is located at other side of the peninsula. These three sites (DB, NT and JSB) with detectable genotoxicity are within 30 km away from the oil spill point. The far-away two sites XHP (38.1 km) and FJZ (31.1 km) were lightly contaminated with oil but no genotoxicity suggesting that they are around the contamination boundary. Bioreporter detection also indicates that all six sites were clean one year after the oil-spill as the alkane and genotoxicity were below detection limit. This study demonstrates that bioreporter detection can be used as a rapid method to estimate the scale of a crude oil spill accident and to evaluate bioavailability and genotoxicity of contaminated seawater and sediments, which are crucial to risk assessment and
-
Mody, Lona; Gibson, Kristen E.; Horcher, Amanda; Prenovost, Katherine; McNamara, Sara E.; Foxman, Betsy; Kaye, Keith S.; Bradley, Suzanne
2015-01-01
OBJECTIVE To characterize the epidemiology of multidrug-resistant (MDR) Acinetobacter baumannii colonization in high-risk nursing home (NH) residents. DESIGN Nested case-control study within a multicenter prospective intervention trial. SETTING Four NHs in Southeast Michigan. PARTICIPANTS Case patients and control subjects were NH residents with an indwelling device (urinary catheter and/or feeding tube) selected from the control arm of the Targeted Infection Prevention study. Cases were residents colonized with MDR (resistant to ≥3 classes of antibiotics) A. baumannii; controls were never colonized with MDR A. baumannii. METHODS For active surveillance cultures, specimens from the nares, oropharynx, groin, perianal area, wounds, and device insertion site(s) were collected upon study enrollment, day 14, and monthly thereafter. A. baumannii strains and their susceptibilities were identified using standard microbiologic methods. RESULTS Of 168 NH residents, 25 (15%) were colonized with MDR A. baumannii. Compared with the 143 controls, cases were more functionally disabled (Physical Self-Maintenance Score >24; odds ratio, 5.1 [95% CI, 1.8–14.9]; P < .004), colonized with Proteus mirabilis (5.8 [1.9–17.9]; P < .003), and diabetic (3.4 [1.2–9.9]; P < .03). Most cases (22 [88%]) were colonized with multiple antibiotic-resistant organisms and 16 (64%) exhibited co-colonization with at least one other resistant gram-negative bacteria. CONCLUSION Functional disability, P. mirabilis colonization, and diabetes mellitus are important risk factors for colonization with MDR A. baumannii in high-risk NH residents. A. baumannii exhibits widespread antibiotic resistance and a preference to colonize with other antibiotic-resistant organisms, meriting enhanced attention and improved infection control practices in these residents. PMID:26072936
-
RNA-Mediated cis Regulation in Acinetobacter baumannii Modulates Stress-Induced Phenotypic Variation
Ching, Carly; Gozzi, Kevin; Heinemann, Björn; Chai, Yunrong
2017-01-01
ABSTRACT In the nosocomial opportunistic pathogen Acinetobacter baumannii, RecA-dependent mutagenesis, which causes antibiotic resistance acquisition, is linked to the DNA damage response (DDR). Notably, unlike the Escherichia coli paradigm, recA and DDR gene expression in A. baumannii is bimodal. Namely, there is phenotypic variation upon DNA damage, which may provide a bet-hedging strategy for survival. Thus, understanding recA gene regulation is key to elucidate the yet unknown DDR regulation in A. baumannii. Here, we identify a structured 5′ untranslated region (UTR) in the recA transcript which serves as a cis-regulatory element. We show that a predicted stem-loop structure in this 5′ UTR affects mRNA half-life and underlies bimodal gene expression and thus phenotypic variation in response to ciprofloxacin treatment. We furthermore show that the stem-loop structure of the recA 5′ UTR influences intracellular RecA protein levels and, in vivo, impairing the formation of the stem-loop structure of the recA 5′ UTR lowers cell survival of UV treatment and decreases rifampin resistance acquisition from DNA damage-induced mutagenesis. We hypothesize that the 5′ UTR allows for stable recA transcripts during stress, including antibiotic treatment, enabling cells to maintain suitable RecA levels for survival. This innovative strategy to regulate the DDR in A. baumannii may contribute to its success as a pathogen. IMPORTANCE Acinetobacter baumannii is an opportunistic pathogen quickly gaining antibiotic resistances. Mutagenesis and antibiotic resistance acquisition are linked to the DNA damage response (DDR). However, how the DDR is regulated in A. baumannii remains unknown, since unlike most bacteria, A. baumannii does not follow the regulation of the Escherichia coli paradigm. In this study, we have started to uncover the mechanisms regulating the novel A. baumannii DDR. We have found that a cis-acting 5′ UTR regulates recA transcript stability, Rec
-
Arduino, Sonia M; Quiroga, María Paula; Ramírez, María Soledad; Merkier, Andrea Karina; Errecalde, Laura; Di Martino, Ana; Smayevsky, Jorgelina; Kaufman, Sara; Centrón, Daniela
2012-10-01
Multiple transposons, integrons and carbapenemases were found in Klebsiella pneumoniae colistin-resistant isolates as well as a genomic resistance island of the AbaR type in Acinetobacter baumannii colistin-resistant isolates from different hospitals from Buenos Aires City. PFGE analysis showed a polyclonal dissemination of antimicrobial resistance mechanisms among K. pneumoniae isolates, while in A. baumannii isolates the epidemic clone 1 from South America was found. Resistance determinants associated with horizontal gene transfer are contributing to the evolution to pandrug resistance in both epidemic and sporadic clones.
-
Lee, Chang-Ro; Lee, Jung Hun; Park, Moonhee; Park, Kwang Seung; Bae, Il Kwon; Kim, Young Bae; Cha, Chang-Jun; Jeong, Byeong Chul; Lee, Sang Hee
2017-01-01
Acinetobacter baumannii is undoubtedly one of the most successful pathogens responsible for hospital-acquired nosocomial infections in the modern healthcare system. Due to the prevalence of infections and outbreaks caused by multi-drug resistant A. baumannii, few antibiotics are effective for treating infections caused by this pathogen. To overcome this problem, knowledge of the pathogenesis and antibiotic resistance mechanisms of A. baumannii is important. In this review, we summarize current studies on the virulence factors that contribute to A. baumannii pathogenesis, including porins, capsular polysaccharides, lipopolysaccharides, phospholipases, outer membrane vesicles, metal acquisition systems, and protein secretion systems. Mechanisms of antibiotic resistance of this organism, including acquirement of β-lactamases, up-regulation of multidrug efflux pumps, modification of aminoglycosides, permeability defects, and alteration of target sites, are also discussed. Lastly, novel prospective treatment options for infections caused by multi-drug resistant A. baumannii are summarized. PMID:28348979
-
Harper, Thomas M; June, Cynthia M; Taracila, Magdalena A; Bonomo, Robert A; Powers, Rachel A; Leonard, David A
2018-01-11
OXA-239 is a class D carbapenemase isolated from an Acinetobacter baumannii strain found in Mexico. This enzyme is a variant of OXA-23 with three amino acid substitutions in or near the active site. These substitutions cause OXA-239 to hydrolyze late-generation cephalosporins and the monobactam aztreonam with greater efficiency than OXA-23. OXA-239 activity against the carbapenems doripenem and imipenem is reduced ∼3-fold and 20-fold, respectively. Further analysis demonstrated that two of the substitutions (P225S and D222N) are largely responsible for the observed alteration of kinetic parameters, while the third (S109L) may serve to stabilize the protein. Structures of OXA-239 with cefotaxime, doripenem and imipenem bound as acyl-intermediates were determined. These structures reveal that OXA-239 has increased flexibility in a loop that contains P225S and D222N. When carbapenems are bound, the conformation of this loop is essentially identical with that observed previously for OXA-23, with a narrow active site that makes extensive contacts to the ligand. When cefotaxime is bound, the loop can adopt a different conformation that widens the active site to allow binding of that bulky drug. This alternate conformation is made possible by P225S and further stabilized by D222N. Taken together, these results suggest that the three substitutions were selected to expand the substrate specificity profile of OXA-23 to cephalosporins and monobactams. The loss of activity against imipenem, however, suggests that there may be limits to the plasticity of class D enzymes with regard to evolving active sites that can effectively bind multiple classes of β-lactam drugs. © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.
-
Tseng, Sung-Pin; Hung, Wei-Chun; Huang, Chiung-Yao; Lin, Yin-Shiou; Chan, Min-Yu; Lu, Po-Liang; Lin, Lin; Sheu, Jyh-Horng
2016-07-29
Nosocomial infections and increasing multi-drug resistance caused by Acinetobacter baumannii have been recognized as emerging problems worldwide. Moreover, A. baumannii is able to colonize various abiotic materials and medical devices, making it difficult to eradicate and leading to ventilator-associated pneumonia, and bacteremia. Development of novel molecules that inhibit bacterial biofilm formation may be an alternative prophylactic option for the treatment of biofilm-associated A. baumannii infections. Marine environments, which are unlike their terrestrial counterparts, harbor an abundant biodiversity of marine organisms that produce novel bioactive natural products with pharmaceutical potential. In this study, we identified 5-episinuleptolide, which was isolated from Sinularia leptoclados, as an inhibitor of biofilm formation in ATCC 19606 and three multi-drug resistant A. baumannii strains. In addition, the anti-biofilm activities of 5-episinuleptolide were observed for Gram-negative bacteria but not for Gram-positive bacteria, indicating that the inhibition mechanism of 5-episinuleptolide is effective against only Gram-negative bacteria. The mechanism of biofilm inhibition was demonstrated to correlate to decreased gene expression from the pgaABCD locus, which encodes the extracellular polysaccharide poly-β-(1,6)-N-acetylglucosamine (PNAG). Scanning electron microscopy (SEM) indicated that extracellular matrix of the biofilm was dramatically decreased by treatment with 5-episinuleptolide. Our study showed potentially synergistic activity of combination therapy with 5-episinuleptolide and levofloxacin against biofilm formation and biofilm cells. These data indicate that inhibition of biofilm formation via 5-episinuleptolide may represent another prophylactic option for solving the persistent problem of biofilm-associated A. baumannii infections.
-
Lesho, Emil; Chukwuma, Uzo; Sparks, Michael; Neumann, Charlotte; Richesson, Douglas; Clifford, Robert; Gierhart, Sarah; Waterman, Paige; Hinkle, Mary
2016-06-01
Carbapenem-resistant Pseudomonas aeruginosa, Acinetobacter spp., and Enterobacteriaceae pose urgent public health threats. The differential burden, relative risks, associations with antimicrobial consumption, and temporal trends of those taxa in large, geographically diverse U.S. health systems remain under reported. Electronic records of all patients in a geographically dispersed 280-hospital managed-care system from 2005 to 2014 were reviewed. Carbapenem-resistant strains were identified based on Clinical and Laboratory Standards Institute guidelines and breakpoints. A total of 360,000 potentially carbapenem-resistant strains were identified from 14.7 million cultures (80% infecting and 20% surveillance). Isolation of bacteria overseas or isolation from the bloodstream was associated with a higher relative risks of carbapenem resistance (CR; P < 0.0001). Enterobacteriaceae were isolated 11 times more frequently than P. aeruginosa and Acinetobacter spp. However, compared to Enterobacteriaceae, the CR levels were 73-fold and 210-fold higher in P. aeruginosa and Acinetobacter spp., respectively. Significant differences in the relative risk of CR between taxa, anatomic, and geographic locations persisted after adjustment for other variables, the biggest differences occurring between taxa. Overall, CR rates increased for Enterobacteriaceae (P = 0.03) and decreased for Acinetobacter spp. and P. aeruginosa (P < 0.0001). These data provide a useful baseline for resistance trending and have implications for surveillance. Infections acquired overseas and bloodstream infections are particularly important areas for continued monitoring. Copyright © 2016 Lesho et al.
-
Yong, Dongeun; Lee, Yangsoon; Jeong, Seok Hoon; Lee, Kyungwon
2012-01-01
Accurate detection of metallo-β-lactamase (MBL)-producing Pseudomonas spp. and Acinetobacter spp. became very important with the increasing prevalence of carbapenem-nonsusceptible clinical isolates. The performance of phenotypic MBL detection methods may depend on the types of MBL and the characteristics of the isolates. A high false-positive rate is a problem with EDTA-based MBL detection methods. We evaluated the performance of double-disk potentiation tests (DDPTs) and disk potentiation tests (DPTs) with dipicolinic acid (DPA) using 44 isolates of Pseudomonas spp. and Acinetobacter spp. producing IMP-1-like, VIM-2-like, and SIM-1 type MBLs. Also, we characterized P. aeruginosa isolates with positive imipenem (IPM)-DPA DDPT, but negative meropenem (MEM)-DPA DDPT, and determined possibility of improving a DDPT by using MacConkey agar. Among five different DDPT methods, the IPM-DPA 250-μg method showed the highest sensitivity (97.7%) and specificity (100%). Among four DPT tests, the highest sensitivity (100%) was shown by the IPM-EDTA 1,900-μg disk method, but the specificity was very low (11.4%). Five of six P. aeruginosa isolates with false-negative DDPTs with MEM-DPA 250-μg disks carried blaIMP-6, and the high level resistance to MEM (MIC ≥ 512 μg/ml) was reduced by the presence of phenylalanine arginine β-naphtylamide. Improvement of DDPTs was observed when MacConkey agar was used instead of Mueller-Hinton agar. In conclusion, DPA is a better MBL inhibitor than EDTA for detection of Pseudomonas spp. and Acinetobacter spp. with IMP-1-like, VIM-2-like, and SIM-1-type MBLs. In DPA DDPTs, IPM disks perform better than MEM disks when the isolates are highly resistant to MEM due to the overexpression of efflux pumps. PMID:22837321
-
Qin, Youfa; Zhang, Jie; Wu, Lei; Zhang, Dailong; Fu, Lunjiao; Xue, Xiaoyan
2018-03-01
The present study examined the effect of high-dose cefoperazone-sulbactam combined with tigecycline against ventilator-associated pneumonia (VAP) caused by extensively drug-resistant Acinetobacter baumannii(XDR-AB). 42 patients with VAP due to XDR-AB infection were randomized into two groups: the TIG group (received tigecycline injection) and the TIG+CFS group (received tigecycline and cefoperazone-sulbactam (1 : 1) injection). Pulsed field gel electrophoresis (PFGE) was used for genotyping the isolated XDR-AB. The microdilution method was used to test the minimum inhibitory concentration (MIC) of cefoperazone-sulbactam or tigecycline in vitro and the combined effect was determined with the checkerboard method. The total combined effectiveness rate (including all patients who demonstrated an improved condition) was significantly higher in the TIG+CFS group (85.7%) compared with the TIG group (47.6%) (p = 0.010). No significant differences were noted with regard to the adverse reactions between the two groups. The 42 isolated XDR-AB strains were classified into four types. The MIC of the two drugs in combination was significantly lower than that of each drug used alone (p < 0.05). High dose of cefoperazone-sulbactam can improve the antimicrobial activity of tigecycline against XDR-AB. .
-
Inaba, Masato; Matsuda, Naoyuki; Banno, Hirotsugu; Jin, Wanchun; Wachino, Jun-Ichi; Yamada, Keiko; Kimura, Kouji; Arakawa, Yoshichika
2016-12-01
The host stress hormone norepinephrine (NE), also called noradrenaline, is reported to augment bacterial growth and pathogenicity, but few studies have focused on the effect of NE on the activity of antimicrobials. The aim of this study was to clarify whether NE affects antimicrobial activity against multidrug-resistant Acinetobacter baumannii (MDR-AB). Time-kill studies of tigecycline (TIG) and colistin (COL) against MDR-AB as well as assays for factors contributing to antibiotic resistance were performed using MDR-AB clinical strains both in the presence and absence of 10 µM NE. In addition, expression of three efflux pump genes (adeB, adeJ and adeG) in the presence and absence of NE was analysed by quantitative reverse transcription PCR. Viable bacterial cell counts in TIG-supplemented medium containing NE were significantly increased compared with those in medium without NE. In contrast, NE had little influence on viable bacterial cell counts in the presence of COL. NE-supplemented medium resulted in an ca. 2 log increase in growth and in bacterial cell numbers adhering on polyurethane, silicone and polyvinylchloride surfaces. Amounts of biofilm in the presence of NE were ca. 3-fold higher than without NE. Expression of the adeG gene was upregulated 4-6-fold in the presence of NE. In conclusion, NE augmented factors contributing to antibiotic resistance and markedly reduced the in vitro antibacterial activity of TIG against MDR-AB. These findings suggest that NE treatment may contribute to the failure of TIG therapy in patients with MDR-AB infections. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.
-
Kitagawa, Wataru; Miyauchi, Keisuke; Masai, Eiji; Fukuda, Masao
2001-01-01
Benzoate catabolism is thought to play a key role in aerobic bacterial degradation of biphenyl and polychlorinated biphenyls (PCBs). Benzoate catabolic genes were cloned from a PCB degrader, Rhodococcus sp. strain RHA1, by using PCR amplification and temporal temperature gradient electrophoresis separation. A nucleotide sequence determination revealed that the deduced amino acid sequences encoded by the RHA1 benzoate catabolic genes, benABCDK, exhibit 33 to 65% identity with those of Acinetobacter sp. strain ADP1. The gene organization of the RHA1 benABCDK genes differs from that of ADP1. The RHA1 benABCDK region was localized on the chromosome, in contrast to the biphenyl catabolic genes, which are located on linear plasmids. Escherichia coli cells containing RHA1 benABCD transformed benzoate to catechol via 2-hydro-1,2-dihydroxybenzoate. They transformed neither 2- nor 4-chlorobenzoates but did transform 3-chlorobenzoate. The RHA1 benA gene was inactivated by insertion of a thiostrepton resistance gene. The resultant mutant strain, RBD169, neither grew on benzoate nor transformed benzoate, and it did not transform 3-chlorobenzoate. It did, however, exhibit diminished growth on biphenyl and growth repression in the presence of a high concentration of biphenyl (13 mM). These results indicate that the cloned benABCD genes could play an essential role not only in benzoate catabolism but also in biphenyl catabolism in RHA1. Six rhodococcal benzoate degraders were found to have homologs of RHA1 benABC. In contrast, two rhodococcal strains that cannot transform benzoate were found not to have RHA1 benABC homologs, suggesting that many Rhodococcus strains contain benzoate catabolic genes similar to RHA1 benABC. PMID:11673430
-
Vignesh, Pandiarajan; Bhattad, Sagar; Shandilya, Jitendra-Kumar; Vyas, Sameer; Garg, Rashi; Rawat, Amit
2016-09-01
Vertebral osteomyelitis is known to occur in chronic granulomatous disease, a phagocytic disorder and the etiology is usually a fungus. Indolent spread of fungal infection from lungs to adjacent ribs and vertebra often results in persistent pneumonia and vertebral deformities. We report a 4-year-old boy with chronic cough and kyphosis, who had a fungal vertebral osteomyelitis and Acinetobacter spp. paravertebral soft tissue infection related to X-linked chronic granulomatous disease.
-
Cloning and Expression of the Benzoate Dioxygenase Genes from Rhodococcus sp. Strain 19070
Haddad, Sandra; Eby, D. Matthew; Neidle, Ellen L.
2001-01-01
The bopXYZ genes from the gram-positive bacterium Rhodococcus sp. strain 19070 encode a broad-substrate-specific benzoate dioxygenase. Expression of the BopXY terminal oxygenase enabled Escherichia coli to convert benzoate or anthranilate (2-aminobenzoate) to a nonaromatic cis-diol or catechol, respectively. This expression system also rapidly transformed m-toluate (3-methylbenzoate) to an unidentified product. In contrast, 2-chlorobenzoate was not a good substrate. The BopXYZ dioxygenase was homologous to the chromosomally encoded benzoate dioxygenase (BenABC) and the plasmid-encoded toluate dioxygenase (XylXYZ) of gram-negative acinetobacters and pseudomonads. Pulsed-field gel electrophoresis failed to identify any plasmid in Rhodococcus sp. strain 19070. Catechol 1,2- and 2,3-dioxygenase activity indicated that strain 19070 possesses both meta- and ortho-cleavage degradative pathways, which are associated in pseudomonads with the xyl and ben genes, respectively. Open reading frames downstream of bopXYZ, designated bopL and bopK, resembled genes encoding cis-diol dehydrogenases and benzoate transporters, respectively. The bop genes were in the same order as the chromosomal ben genes of P. putida PRS2000. The deduced sequences of BopXY were 50 to 60% identical to the corresponding proteins of benzoate and toluate dioxygenases. The reductase components of these latter dioxygenases, BenC and XylZ, are 201 residues shorter than the deduced BopZ sequence. As predicted from the sequence, expression of BopZ in E. coli yielded an approximately 60-kDa protein whose presence corresponded to increased cytochrome c reductase activity. While the N-terminal region of BopZ was approximately 50% identical in sequence to the entire BenC or XylZ reductases, the C terminus was unlike other known protein sequences. PMID:11375157
-
The detection of antigenic determinants of Acinetobacter baumannii.
Tawfik, Dina M; Ahmad, Tarek A; Sheweita, Salah A; Haroun, Medhat; El-Sayed, Laila H
2017-06-01
Acinetobacter baumannii continues to pose a threat to burdened patients in ICUs all around the world. Lately, infection control techniques are not sufficient to curb A. baumannii's progression and chemotherapeutics are losing their potency against it. Thus, immunization became a key player in providing an ideal solution to the dilemma. None of the vaccines under investigation have reached the market and the search for a tailored vaccine remains a challenge. The notion of unravelling the bacterial antigens to design a novel epitope-based vaccine proved its merits. In this work, the propitious polysaccharide and protein antigenic determinants of A. baumannii were mapped by mimicking the infection. The immune response was evaluated by western blot, ELISA, and cellular proliferation assay techniques. The screening showed that OMPs induced the most eminent sustained IgG response. In addition, OMP gave the highest cellular proliferation and a fold increase in ELISA that reached up to 10-fold by week 6. Whilst, the LPS gave a rapid IgM response, that reached 5-fold and the response was visible from week 1 in the western blot. The OMPs had a more pronounced effect in eliciting a cellular immune response. The results elaborated the valuable role of using pure OMPs and detoxified LPS together; as a major cornerstone in designing an ideal vaccine against A. baumannii. Copyright © 2017 European Federation of Immunological Societies. Published by Elsevier B.V. All rights reserved.
-
Sahl, Jason W; Johnson, J Kristie; Harris, Anthony D; Phillippy, Adam M; Hsiao, William W; Thom, Kerri A; Rasko, David A
2011-06-04
Acinetobacter baumannii has recently emerged as a significant global pathogen, with a surprisingly rapid acquisition of antibiotic resistance and spread within hospitals and health care institutions. This study examines the genomic content of three A. baumannii strains isolated from distinct body sites. Isolates from blood, peri-anal, and wound sources were examined in an attempt to identify genetic features that could be correlated to each isolation source. Pulsed-field gel electrophoresis, multi-locus sequence typing and antibiotic resistance profiles demonstrated genotypic and phenotypic variation. Each isolate was sequenced to high-quality draft status, which allowed for comparative genomic analyses with existing A. baumannii genomes. A high resolution, whole genome alignment method detailed the phylogenetic relationships of sequenced A. baumannii and found no correlation between phylogeny and body site of isolation. This method identified genomic regions unique to both those isolates found on the surface of the skin or in wounds, termed colonization isolates, and those identified from body fluids, termed invasive isolates; these regions may play a role in the pathogenesis and spread of this important pathogen. A PCR-based screen of 74 A. baumanii isolates demonstrated that these unique genes are not exclusive to either phenotype or isolation source; however, a conserved genomic region exclusive to all sequenced A. baumannii was identified and verified. The results of the comparative genome analysis and PCR assay show that A. baumannii is a diverse and genomically variable pathogen that appears to have the potential to cause a range of human disease regardless of the isolation source.
-
Lu, Po-Liang; Siu, L K; Chen, Tun-Chieh; Ma, Ling; Chiang, Wen-Gin; Chen, Yen-Hsu; Lin, Sheng-Fung; Chen, Tyen-Po
2009-10-01
Computer keyboards and mice are potential reservoirs of nosocomial pathogens, but routine disinfection for non-water-proof computer devices is a problem. With better hand hygiene compliance of health-care workers (HCWs), the impact of these potential sources of contamination on clinical infection needs to be clarified. This study was conducted in a 1600-bed medical center of southern Taiwan with 47 wards and 282 computers. With education and monitoring program of hand hygiene for HCWs, the average compliance rate was 74% before our surveillance. We investigated the association of methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Acinetobacter baumannii, three leading hospital-acquired pathogens, from ward computer keyboards, mice and from clinical isolates in non-outbreak period by pulsed field gel electrophoresis and antibiogram. Our results revealed a 17.4% (49/282) contamination rate of these computer devices by S. aureus, Acinetobacter spp. or Pseudomonas spp. The contamination rates of MRSA and A. baumannii in the ward computers were 1.1% and 4.3%, respectively. No P. aeruginosa was isolated. All isolates from computers and clinical specimens at the same ward showed different pulsotypes. However, A. baumannii isolates on two ward computers had the same pulsotype. With good hand hygiene compliance, we found relatively low contamination rates of MRSA, P. aeruginosa and A. baumannii on ward computer interface, and without further contribution to nosocomial infection. Our results suggested no necessity of routine culture surveillance in non-outbreak situation.
-
2009-01-01
Background Computer keyboards and mice are potential reservoirs of nosocomial pathogens, but routine disinfection for non-water-proof computer devices is a problem. With better hand hygiene compliance of health-care workers (HCWs), the impact of these potential sources of contamination on clinical infection needs to be clarified. Methods This study was conducted in a 1600-bed medical center of southern Taiwan with 47 wards and 282 computers. With education and monitoring program of hand hygiene for HCWs, the average compliance rate was 74% before our surveillance. We investigated the association of methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Acinetobacter baumannii, three leading hospital-acquired pathogens, from ward computer keyboards, mice and from clinical isolates in non-outbreak period by pulsed field gel electrophoresis and antibiogram. Results Our results revealed a 17.4% (49/282) contamination rate of these computer devices by S. aureus, Acinetobacter spp. or Pseudomonas spp. The contamination rates of MRSA and A. baumannii in the ward computers were 1.1% and 4.3%, respectively. No P. aeruginosa was isolated. All isolates from computers and clinical specimens at the same ward showed different pulsotypes. However, A. baumannii isolates on two ward computers had the same pulsotype. Conclusion With good hand hygiene compliance, we found relatively low contamination rates of MRSA, P. aeruginosa and A. baumannii on ward computer interface, and without further contribution to nosocomial infection. Our results suggested no necessity of routine culture surveillance in non-outbreak situation. PMID:19796381
-
Kenters, Nikki; Huijskens, Elisabeth G W; de Wit, Sophie C J; van Rosmalen, Joost; Voss, Andreas
2017-08-01
Hospital rooms play an important role in the transmission of several health care-associated pathogens. During the last few years, a number of innovative cleaning-disinfecting products have been brought to market. In this study, commercially available products combining cleaning and disinfection were compared, using 2 different application methods. The aim was to determine which product was most effective in simultaneous cleaning and disinfection of surfaces. Seven cleaning-disinfecting wipes and sprays based on different active ingredients were tested for their efficacy in removal of microbial burden and proteins. Efficacy was tested with known Dutch outbreak strains: vancomycin-resistant enterococci (VRE), Klebsiella pneumoniae OXA-48, or Acinetobacter baumannii. For all bacteria, ready-to-use cleaning-disinfecting products reduced the microbial count with a log 10 reduction >5 with a 5-minute exposure time, with the exception of a spray based on hydrogen peroxide. Omitting the aforementioned hydrogen peroxide spray, there were no significant differences between use of a wipe or spray in bacterial load reduction. Using adenosine triphosphate (ATP) measurements, a significant difference in log 10 relative light units (RLU) reduction between various bacteria (P ≤ .001) was observed. In general, a >5 log 10 reduction of colony forming units (CFU) for tested wipes and sprays was obtained for all tested bacteria strains, with exception of hydrogen peroxide spray and VRE. Although ATP may show a difference between pre- and postcleaning, RLU reduction does not correlate with actual CFU reductions. Copyright © 2017 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
-
Wencewicz, Timothy A.; Miller, Marvin J.
2013-01-01
Chemical syntheses and biological evaluation of biscatecholate-monohydroxamate mixed ligand sideromycins utilizing the carbacephalosporin β-lactam antibiotic loracarbef and the fluo-roquinolone antibiotic ciprofloxacin are described. The mixed ligand β-lactam sideromycin (1b) had remarkably selective and extremely potent antibacterial activity against the Gram negative pathogen Acinetobacter baumannii ATCC 17961 (MIC = 0.0078 μM). The antibacterial activity of the β-lactam sideromycin was inversely related to the iron(III) concentration in the testing media and was antagonized by the presence of the competing parent siderophore. These data suggested that active transport of the mixed ligand β-lactam sideromycin across the outer cell membrane of A. baumannii via siderophore uptake pathways was responsible for the selective and potent antibacterial activity. PMID:23614627
-
Argemi, Xavier; Nanoukon, Chimène; Affolabi, Dissou; Keller, Daniel; Hansmann, Yves; Riegel, Philippe; Baba-Moussa, Lamine; Prévost, Gilles
2018-02-25
Staphylococcus epidermidis is a leading cause of nosocomial infections, majorly resistant to beta-lactam antibiotics, and may transfer several mobile genetic elements among the members of its own species, as well as to Staphylococcus aureus ; however, a genetic exchange from S. aureus to S. epidermidis remains controversial. We recently identified two pathogenic clinical strains of S. epidermidis that produce a staphylococcal enterotoxin C3-like (SEC) similar to that by S. aureus pathogenicity islands. This study aimed to determine the genetic environment of the SEC-coding sequence and to identify the mobile genetic elements. Whole-genome sequencing and annotation of the S. epidermidis strains were performed using Illumina technology and a bioinformatics pipeline for assembly, which provided evidence that the SEC-coding sequences were located in a composite pathogenicity island that was previously described in the S. epidermidis strain FRI909, called SePI-1/SeCI-1, with 83.8-89.7% nucleotide similarity. Various other plasmids were identified, particularly p_3_95 and p_4_95, which carry antibiotic resistance genes ( hsrA and dfrG , respectively), and share homologies with SAP085A and pUSA04-2-SUR11, two plasmids described in S. aureus . Eventually, one complete prophage was identified, ΦSE90, sharing 30 out of 52 coding sequences with the Acinetobacter phage vB_AbaM_IME200. Thus, the SePI-1/SeCI-1 pathogenicity island was identified in two pathogenic strains of S. epidermidis that produced a SEC enterotoxin causing septic shock. These findings suggest the existence of in vivo genetic exchange from S. aureus to S. epidermidis .
-
Nanoukon, Chimène; Affolabi, Dissou; Keller, Daniel; Hansmann, Yves; Riegel, Philippe; Baba-Moussa, Lamine; Prévost, Gilles
2018-01-01
Staphylococcus epidermidis is a leading cause of nosocomial infections, majorly resistant to beta-lactam antibiotics, and may transfer several mobile genetic elements among the members of its own species, as well as to Staphylococcus aureus; however, a genetic exchange from S. aureus to S. epidermidis remains controversial. We recently identified two pathogenic clinical strains of S. epidermidis that produce a staphylococcal enterotoxin C3-like (SEC) similar to that by S. aureus pathogenicity islands. This study aimed to determine the genetic environment of the SEC-coding sequence and to identify the mobile genetic elements. Whole-genome sequencing and annotation of the S. epidermidis strains were performed using Illumina technology and a bioinformatics pipeline for assembly, which provided evidence that the SEC-coding sequences were located in a composite pathogenicity island that was previously described in the S. epidermidis strain FRI909, called SePI-1/SeCI-1, with 83.8–89.7% nucleotide similarity. Various other plasmids were identified, particularly p_3_95 and p_4_95, which carry antibiotic resistance genes (hsrA and dfrG, respectively), and share homologies with SAP085A and pUSA04-2-SUR11, two plasmids described in S. aureus. Eventually, one complete prophage was identified, ΦSE90, sharing 30 out of 52 coding sequences with the Acinetobacter phage vB_AbaM_IME200. Thus, the SePI-1/SeCI-1 pathogenicity island was identified in two pathogenic strains of S. epidermidis that produced a SEC enterotoxin causing septic shock. These findings suggest the existence of in vivo genetic exchange from S. aureus to S. epidermidis. PMID:29495323
-
Wang, Yanhong; Shen, Min; Yang, Jingni; Dai, Min; Chang, Yaowen; Zhang, Chi; Luan, Guangxin; Ling, Baodong; Jia, Xu
2016-01-01
The prevalence of aminoglycoside resistant enzymes has previously been reported and extended-spectrum β-lactamase among Acinetobacter baumannii. To track the risk of multidrug-resistant A. baumannii, the present study aimed to determine the prevalence of carbapenemases in high-level aminoglycoside resistant A. baumannii over two years. A total of 118 strains of A. baumannii were consecutively collected in the First Affiliated Hospital of Chengdu Medical College, Chengdu, China. These isolates were investigated on the genetic basis of their resistance to aminoglycosides. The results showed that 75 (63.56%) isolates were high-level resistant to aminoglycosides, including gentamicin and amikacin (minimum inhibitory concentration, ≥256 µg/ml). Aminoglycoside-resistant genes ant(2″)-Ia, aac(6′)-Ib, aph(3′)-Ia, aac(3)-Ia, aac(3)-IIa, armA, rmtA, rmtB, rmtC, rmtD, rmtE, rmtF, rmtG, rmtH and npmA, and carbapenem-resistant genes blaOXA-23, blaOXA-24, blaOXA-51, blaOXA-58, blaSIM, blaIMP, blaNDM-1 and blaKPC, were analyzed using polymerase chain reaction. The positive rate of ant(2″)-Ia, aac(6′)-Ib, aph(3′)-Ia, aac(3)-Ia and aac(3)-IIa was 66.95, 69.49, 42.37, 39.83 and 14.41%, respectively. armA was present in 72.0% (54/75) of A. baumannii isolates with high-level resistance to aminoglycosides. The remaining nine 16S ribosomal RNA methlyase genes (rmtA, rmtB, rmtC, rmtD, rmtE, rmtF, rmtG, rmtH and npmA) and aminoglycoside-modifying enzyme gene aac(6′)-Ib-cr were not detected. Among the 54 armA-positive isolates, the prevalence of the carbapenem resistant blaOXA-23 and blaOXA-51 genes was 79.63 and 100%, respectively. armA, ant(2″)-Ia and aac(6′)-Ib were positive in 43 isolates. The results of multilocus sequence typing revealed 31 sequence types (STs) in all clinical strains. Among these STs, the high-level aminoglycoside-resistant A. baumannii ST92, which mostly harbored blaOXA-23, was the predominant clone (29/75). In conclusion, A. baumannii
-
Begum, Shahzeera; Hasan, Fariha; Hussain, Shagufta; Ali Shah, Aamer
2013-01-01
Background & Objectives: Acinetobacter baumannii can cause a wide range of infections, including bacteremia, pneumonia, urinary tract infection, peritonitis, etc. This organism is becoming resistant to a large group of antibiotics, especially β-lactam antibiotics. The reason for multi-drug resistance may be the production of extended- spectrum β-lactamses (ESBLs), carbapenemases/metallo β-lactamases or AmpC β-lactamases. The aim of the present study was to determine the prevalence of multi-drug resistant Acinetobacter baumannii isolated from the patients in Surgical Intensive Care Units (SICUs) of Pakistan Institute of Medical Sciences (PIMS), Islamabad, Pakistan. Methods: A total of 91 A. baumanni isolates were collected from PIMS during the period from February 2011 to December 2011. The antibiotic susceptibility testing was performed by standard disc diffusion method as recommended by CLSI. Combination disc method, Modified Hodge test, EDTA disc synergy test and AmpC disc test were performed for detection of ESBLs, carbapenemases, metallo β-lactamases, and AmpC β-lactamases, respectively. Results: The prevalence of MDRs was reported 100% among A. baumannii. The antibiotic susceptibility profile showed that minocycline and tigecycline were the most effective drugs against A. baumannii. Almost all of A. baumannii isolates were carbapenemase and metallo β-lactamase producers. AmpC prevalence was observed in 41.76%, while none of the isolates was ESBL producer. Antibiogram and minimal inhibitory concentrations (MICs) indicated tetracycline is relatively effective against A. baumanii. Conclusions: Increased frequency of multi-drug resistance supports the need for continuous surveillance to determine prevalence and evolution of these enzymes in Pakistan. PMID:24353731
-
Ajiboye, Taofeek O; Skiebe, Evelyn; Wilharm, Gottfried
2018-05-01
Phenolic acids with catechol groups are good prooxidants because of their low redox potential. In this study, we provided data showing that phenolic acids, caffeic acid, gallic acid and protocatechuic acid, enhanced colistin-mediated bacterial death by inducing redox imbalance. The minimum inhibitory concentrations of these phenolic acids against Acinetobacter baumannii AB5075 were considerably lowered for ΔsodB and ΔkatG mutants. Checkerboard assay shows synergistic interactions between colistin and phenolic acids. The phenolic acids exacerbated colistin-induced oxidative stress in A. baumannii AB5075 through increased superoxide anion generation, NAD + /NADH and ADP/ATP ratio. In parallel, the level of reduced glutathione was significantly lowered. We conclude that phenolic acids potentiate colistin-induced oxidative stress in A. baumannii AB5075 by increasing ROS generation, energy metabolism and electron transport chain activity with a concomitant decrease in glutathione. Copyright © 2018 Elsevier Masson SAS. All rights reserved.
-
Jamal, Sabah; Atrouni, Ahmad Al; Rafei, Rayane; Dabboussi, Fouad; Hamze, Monzer; Osman, Marwan
2018-05-30
Acinetobacter baumannii is an opportunistic bacterium involved in several types of infection with high mortality and morbidity, especially in intensive care units. Treatment of these infections remains a challenge due to the worldwide emergence of broad-spectrum resistance to many antibiotics. Following the implementation of molecular techniques to study A. baumannii outbreaks, it has been shown that they are mainly caused by specific clones like international clone 1, 2 and 3. The present work aims to review the available data on the mechanisms underlying the antimicrobial resistance in A. baumannii with a special focus on the molecular epidemiology of this species in Lebanon. Copyright © 2018. Published by Elsevier Ltd.
-
Characterization and Transcriptome Analysis of Acinetobacter baumannii Persister Cells.
Alkasir, Rashad; Ma, Yanan; Liu, Fei; Li, Jing; Lv, Na; Xue, Yong; Hu, Yongfei; Zhu, Baoli
2018-06-14
Acinetobacter baumannii is a nonfermenting Gram-negative bacillus. A. baumannii resistance is a significant obstacle to clinical infection treatment. The existence of persister cells (persisters) might represent the reason for therapy failure and relapse, and such cells may be the driving force behind rising resistance rates. In this study, A. baumannii ATCC 19606 was used as a target to explore the essential features of A. baumannii persisters. Antibiotic treatment of A. baumannii cultures at 50-fold the minimum inhibitory concentration resulted in a distinct plateau of surviving drug-tolerant persisters. The sensitive bacteria were lysed with ceftazidime, and the nonreplicating bacteria were isolated for transcriptome analysis using RNA sequencing. We analyzed the transcriptome of A. baumannii persisters and identified significantly differentially expressed genes, as well as their enriched pathways. The results showed that both the GP49 (HigB)/Cro (HigA) and DUF1044/RelB toxin/antitoxin systems were significantly increased during the persister incubation period. In addition, the activities of certain metabolic pathways (such as electron transport, adenosine triphosphate [ATP], and the citrate cycle) decreased sharply after antibiotic treatment and remained low during the persister period, while aromatic compound degradation genes were only upregulated in persisters. These results suggest the involvement of aromatic compound degradation genes in persister formation and maintenance. They further provide the first insight into the mechanism of persister formation in A. baumannii.
-
Perchat, Nadia; Saaidi, Pierre-Loïc; Darii, Ekaterina; Pellé, Christine; Petit, Jean-Louis; Besnard-Gonnet, Marielle; de Berardinis, Véronique; Dupont, Maeva; Gimbernat, Alexandra; Salanoubat, Marcel; Fischer, Cécile; Perret, Alain
2018-05-08
Trigonelline (TG; N- methylnicotinate) is a ubiquitous osmolyte. Although it is known that it can be degraded, the enzymes and metabolites have not been described so far. In this work, we challenged the laboratory model soil-borne, gram-negative bacterium Acinetobacter baylyi ADP1 (ADP1) for its ability to grow on TG and we identified a cluster of catabolic, transporter, and regulatory genes. We dissected the pathway to the level of enzymes and metabolites, and proceeded to in vitro reconstruction of the complete pathway by six purified proteins. The four enzymatic steps that lead from TG to methylamine and succinate are described, and the structures of previously undescribed metabolites are provided. Unlike many aromatic compounds that undergo hydroxylation prior to ring cleavage, the first step of TG catabolism proceeds through direct cleavage of the C5-C6 bound, catalyzed by a flavin-dependent, two-component oxygenase, which yields ( Z )-2-(( N- methylformamido)methylene)-5-hydroxy-butyrolactone (MFMB). MFMB is then oxidized into ( E )-2-(( N- methylformamido) methylene) succinate (MFMS), which is split up by a hydrolase into carbon dioxide, methylamine, formic acid, and succinate semialdehyde (SSA). SSA eventually fuels up the TCA by means of an SSA dehydrogenase, assisted by a Conserved Hypothetical Protein. The cluster is conserved across marine, soil, and plant-associated bacteria. This emphasizes the role of TG as a ubiquitous nutrient for which an efficient microbial catabolic toolbox is available.
-
Zawadzke, Laura E; Norcia, Michael; Desbonnet, Charlene R; Wang, Hong; Freeman-Cook, Kevin; Dougherty, Thomas J
2008-02-01
The pathway for synthesis of the peptidoglycan precursor UDP-N-acetylmuramyl pentapeptide is essential in Gram-positive and Gram-negative bacteria. This pathway has been exploited in the recent past to identify potential new antibiotics as inhibitors of one or more of the Mur enzymes. In the present study, a high-throughput screen was employed to identify potential inhibitors of the Escherichia coli MurC (UDP-N-acetylmuramic acid:L-alanine ligase), the first of four paralogous amino acid-adding enzymes. Inhibition of ATP consumed during the MurC reaction, using an adaptation of a kinase assay format, identified a number of potential inhibitory chemotypes. After nonspecific inhibition testing and chemical attractiveness were assessed, C-1 emerged as a compound for further characterization. The inhibition of MurC by this compound was confirmed in both a kinetic-coupled enzyme assay and a direct nuclear magnetic resonance product detection assay. C-1 was found to be a low micromolar inhibitor of the E. coli MurC reaction, with preferential inhibition by one of two enantiomeric forms. Experiments indicated that it was a competitive inhibitor of ATP binding to the MurC enzyme. Further work with MurC enzymes from several bacterial sources revealed that while the compound was equally effective at inhibiting MurC from genera (Proteus mirabilis and Klebsiella pneumoniae) closely related to E. coli, MurC enzymes from more distant Gram-negative species such as Haemophilus influenzae, Acinetobacter baylyi, and Pseudomonas aeruginosa were not inhibited.
-
Walzer, Gil; Rosenberg, Eugene; Ron, Eliora Z
2009-01-01
Microbial bioemulsifiers are secreted by many bacteria and are important for bacterial interactions with hydrophobic substrates or nutrients and for a variety of biotechnological applications. We have recently shown that the OmpA protein in several members of the Acinetobacter family has emulsifying properties. These properties of OmpA depend on the amino acid composition of four putative extra-membrane loops, which in various strains of Acinetobacter, but not in E. coli, are highly hydrophobic. As many Acinetobacter strains can utilize hydrophobic carbon sources, such as oil, the emulsifying activity of their OmpA may be important for the utilization and uptake of hydrocarbons. We assumed that if outer membrane proteins with emulsifying activity are physiologically important, they may exist in additional oil degrading bacteria. In order to identify such proteins, it was necessary to obtain bioinformatics-based predictions for hydrophobic extra-membrane loops. Here we describe a method for using protein sequence data for predicting the hydrophobic properties of the extra-membrane loops of outer membrane proteins. The feasibility of this method is demonstrated by its use to identify a new microbial bioemulsifier - OprG - an outer membrane protein of the oil degrading Pseudomonas putida KT2440.
-
Zhang, Yunsong; Zhu, Yingbo; Gupta, Asheesh; Huang, Yingying; Murray, Clinton K.; Vrahas, Mark S.; Sherwood, Margaret E.; Baer, David G.; Hamblin, Michael R.; Dai, Tianhong
2014-01-01
In this study, we investigated the utility of antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model. A bioluminescent clinical isolate of multidrug-resistant A. baumannii was obtained. The susceptibility of A. baumannii to blue light (415 nm)–inactivation was compared in vitro to that of human keratinocytes. Repeated cycles of sublethal inactivation of bacterial by blue light were performed to investigate the potential resistance development of A. baumannii to blue light. A mouse model of third degree burn infected with A. baumannii was developed. A single exposure of blue light was initiated 30 minutes after bacterial inoculation to inactivate A. baumannii in mouse burns. It was found that the multidrug-resistant A. baumannii strain was significantly more susceptible than keratinocytes to blue light inactivation. Transmission electron microscopy revealed blue light–induced ultrastructural damage in A. baumannii cells. Fluorescence spectroscopy suggested that endogenous porphyrins exist in A. baumannii cells. Blue light at an exposure of 55.8 J/cm2 significantly reduced the bacterial burden in mouse burns. No resistance development to blue light inactivation was observed in A. baumannii after 10 cycles of sublethal inactivation of bacteria. No significant DNA damage was detected in mouse skin by means of a skin TUNEL assay after a blue light exposure of 195 J/cm2. PMID:24381206
-
Müller, Gabriela L.; Tuttobene, Marisel; Altilio, Matías; Martínez Amezaga, Maitena; Nguyen, Meaghan; Cribb, Pamela; Cybulski, Larisa E.; Ramírez, María Soledad; Altabe, Silvia
2017-01-01
ABSTRACT Light sensing in chemotrophic bacteria has been relatively recently ascertained. In the human pathogen Acinetobacter baumannii, light modulates motility, biofilm formation, and virulence through the blue-light-sensing-using flavin (BLUF) photoreceptor BlsA. In addition, light can induce a reduction in susceptibility to certain antibiotics, such as minocycline and tigecycline, in a photoreceptor-independent manner. In this work, we identified new traits whose expression levels are modulated by light in this pathogen, which comprise not only important determinants related to pathogenicity and antibiotic resistance but also metabolic pathways, which represents a novel concept for chemotrophic bacteria. Indeed, the phenylacetic acid catabolic pathway and trehalose biosynthesis were modulated by light, responses that completely depend on BlsA. We further show that tolerance to some antibiotics and modulation of antioxidant enzyme levels are also influenced by light, likely contributing to bacterial persistence in adverse environments. Also, we present evidence indicating that surfactant production is modulated by light. Finally, the expression of whole pathways and gene clusters, such as genes involved in lipid metabolism and genes encoding components of the type VI secretion system, as well as efflux pumps related to antibiotic resistance, was differentially induced by light. Overall, our results indicate that light modulates global features of the A. baumannii lifestyle. IMPORTANCE The discovery that nonphototrophic bacteria respond to light constituted a novel concept in microbiology. In this context, we demonstrated that light could modulate aspects related to bacterial virulence, persistence, and resistance to antibiotics in the human pathogen Acinetobacter baumannii. In this work, we present the novel finding that light directly regulates metabolism in this chemotrophic bacterium. Insights into the mechanism show the involvement of the photoreceptor Bls
-
Müller, Gabriela L; Tuttobene, Marisel; Altilio, Matías; Martínez Amezaga, Maitena; Nguyen, Meaghan; Cribb, Pamela; Cybulski, Larisa E; Ramírez, María Soledad; Altabe, Silvia; Mussi, María Alejandra
2017-05-15
Light sensing in chemotrophic bacteria has been relatively recently ascertained. In the human pathogen Acinetobacter baumannii , light modulates motility, biofilm formation, and virulence through the blue-light-sensing-using flavin (BLUF) photoreceptor BlsA. In addition, light can induce a reduction in susceptibility to certain antibiotics, such as minocycline and tigecycline, in a photoreceptor-independent manner. In this work, we identified new traits whose expression levels are modulated by light in this pathogen, which comprise not only important determinants related to pathogenicity and antibiotic resistance but also metabolic pathways, which represents a novel concept for chemotrophic bacteria. Indeed, the phenylacetic acid catabolic pathway and trehalose biosynthesis were modulated by light, responses that completely depend on BlsA. We further show that tolerance to some antibiotics and modulation of antioxidant enzyme levels are also influenced by light, likely contributing to bacterial persistence in adverse environments. Also, we present evidence indicating that surfactant production is modulated by light. Finally, the expression of whole pathways and gene clusters, such as genes involved in lipid metabolism and genes encoding components of the type VI secretion system, as well as efflux pumps related to antibiotic resistance, was differentially induced by light. Overall, our results indicate that light modulates global features of the A. baumannii lifestyle. IMPORTANCE The discovery that nonphototrophic bacteria respond to light constituted a novel concept in microbiology. In this context, we demonstrated that light could modulate aspects related to bacterial virulence, persistence, and resistance to antibiotics in the human pathogen Acinetobacter baumannii In this work, we present the novel finding that light directly regulates metabolism in this chemotrophic bacterium. Insights into the mechanism show the involvement of the photoreceptor BlsA. In
-
Na, In Young; Chung, Eun Seon; Jung, Chang-Yun; Kim, Dae Hun; Shin, Juyoun; Kang, KyeongJin; Kim, Seong-Tae; Ko, Kwan Soo
2016-01-01
In this study, we compared the virulence-associated factors of Acinetobacter baumannii complex species. Sixty-three isolates of five A. baumannii complex species, including 19 A. baumannii, 15 A. nosocomialis, 13 A. seifertii, 13 A. pittii, and 3 A. calcoaceticus isolates, were included in this study. For all isolates, biofilm formation, A549 cell adherence, resistance to normal human serum, and motility were evaluated. A. baumannii complex isolates showed diversity in biofilm formation, A549 cell adherence, and serum resistance, and no strong positive relationships among these virulence characteristics. However, A. seifertii showed relatively consistent virulence-associated phenotypes. In addition, A. baumannii clone ST110 exhibited consistently high virulence-associated phenotypes. Motility was observed in seven isolates, and all four A. baumannii ST110 isolates showed twitching motility. Although some inconsistencies in virulence-associated phenotypes were seen, high virulence characteristics were observed in A. seifertii, which has been mainly reported in Korea and shows high rates of colistin resistance.
-
Ganjo, Aryann R; Maghdid, Delshad M; Mansoor, Isam Y; Kok, Dik J; Severin, Juliette A; Verbrugh, Henri A; Kreft, Deborah; Fatah, M H; Alnakshabandi, A A; Dlnya, Asad; Hammerum, Anette M; Ng, Kim; Goessens, Wil
2016-12-01
In addition to intrinsic resistance in Acinetobacter baumannii, many different types of acquired resistance mechanisms have been reported, including the presence of VIM and IMP metallo β-lactamases and also of bla OXA-23-like and bla OXA-58-like enzymes. In the Kurdistan region of Iraq, the multiresistant A. baumannii-calcoaceticus complex is prevalent. We characterized the different mechanisms of resistance present in clinical isolates collected from different wards and different hospitals from the Kurdistan region. One hundred twenty clinical nonduplicate A. baumannii-calcoaceticus complex isolates were collected from four hospitals between January 2012 and October 2013. The identification of the isolates was confirmed by MALDI-TOF. The susceptibility to different antibiotics was determined by disk diffusion and analyzed in accordance to EUCAST guidelines. By PCR, the presence of bla OXA-51-like , bla OXA-23-like , bla OXA-24-like , and bla OXA-58-like genes was determined as well as the presence of the insertion element ISAba1. Clonal diversity was analyzed by pulsed-field gel electrophoresis (PFGE) using the restriction enzyme ApaI and, in addition, multilocus sequence typing (MLST) was performed on a selected subset of 15 isolates. All 120 A. baumannii isolates harbored bla OXA-51-like genes. One hundred one out of 110 (92%) imipenem (IMP)-resistant A. baumannii-calcoaceticus complex isolates additionally carried the bla OXA-23-like gene and four isolates (3%) were positive for bla OXA-24-like. All 101 bla OXA-23-like -positive isolates had the ISAba1 insertion sequence, 1,600 bp upstream of the bla OXA-23-like gene. The bla OXA-58-like gene was not detected in any of the 110 IMP-resistant strains. Eight different PFGE clusters were identified and distributed over the different hospitals. MLST analysis performed on a subset of 15 representative isolates revealed the presence of the international clone ST2 (Pasteur). Besides ST2 (Pasteur), also many other
-
Molter, G; Seifert, H; Mandraka, F; Kasper, G; Weidmann, B; Hornei, B; Öhler, M; Schwimmbeck, P; Kröschel, P; Higgins, P G; Reuter, S
2016-02-01
An outbreak of carbapenem-resistant Acinetobacter baumannii (CRAb) occurred in an interdisciplinary intensive care unit, affecting 10 patients. Within hours of recognition of the spread of CRAb an intervention team was instituted for collection of available data, decision-making, communication and monitoring of all interventions performed, including cohorting, temporary stop of admissions, staff education, and enforcement of infection control measures. An area was defined for cohortation of patients colonized with CRAb, with a separate nursing team and a second set of mobile equipment. New transmissions were no longer observed after only four days into the institution of enhanced infection control measures. Copyright © 2015 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
-
Méndez, Jose Antonio; Mateos, Jesús; Beceiro, Alejandro; Lopez, María; Tomás, María; Poza, Margarita; Bou, Germán
2015-05-30
Acinetobacter baumannii is a major health problem. The most common infection caused by A. baumannii is hospital acquired pneumonia, and the associated mortality rate is approximately 50%. Neither in vivo nor ex vivo expression profiling has been performed at the proteomic or transcriptomic level for pneumonia caused by A. baumannii. In this study, we characterized the proteome of A. baumannii under conditions that simulate those found in the airways, to gain some insight into how A. baumannii adapts to the host and to improve knowledge about the pathogenesis and virulence of this bacterium. A clinical strain of A. baumannii was grown under different conditions: in the presence of bronchoalveolar lavage fluid from infected rats, of RAW 264.7 cells to simulate conditions in the respiratory tract and in control conditions. We used iTRAQ labelling and LC-MALDI-TOF/TOF to investigate how A. baumannii responds on exposure to macrophages/BALF. 179 proteins showed differential expression. In both models, proteins involved in the following processes were over-expressed: (i) pathogenesis and virulence (OmpA, YjjK); (ii) cell wall/membrane/envelope biogenesis (MurC); (iii) energy production and conversion (acetyl-CoA hydrolase); and (iv) translation (50S ribosomal protein L9). Proteins involved in the following were under-expressed: (i) lipid metabolism (short-chain dehydrogenase); (ii) amino acid metabolism and transport (aspartate aminotransferase); (iii) unknown function (DNA-binding protein); and (iv) inorganic ion transport and metabolism (hydroperoxidase). We observed alterations in cell wall synthesis and identified 2 upregulated virulence-associated proteins with >15 peptides/protein in both ex vivo models (OmpA and YjjK), suggesting that these proteins are fundamental for pathogenesis and virulence in the airways. This study is the first comprehensive overview of the ex vivo proteome of A. baumannii and is an important step towards identification of diagnostic
-
Dekić, Svjetlana; Klobučar, Göran; Ivanković, Tomislav; Zanella, Davor; Vucić, Matej; Bourdineaud, Jean-Paul; Hrenović, Jasna
2018-05-08
Bacterium Acinetobacter baumannii is an emerging human pathogen whose presence in the aquatic environment raises the issue of public health risk. Fish colonization represents the potential route of pathogen transmission to humans. The aim was to examine the colonization of A. baumannii to freshwater fish Poecilia reticulata. An extensively drug-resistant A. baumannii was tested at three concentrations in natural spring water. Additionally, 70 fish from the Sava River (Croatia) were screened for the presence of A. baumannii, which was not found in gill swabs or analysed gut. The colonization potential of A. baumannii in freshwater fish is dependent upon its concentration in surrounding water. The low concentration of A. baumannii in natural waters represents low colonization potential of freshwater fish. The risk for public health exists in closed water bodies where there is constant inflow of water polluted by A. baumannii in concentrations above 3 log CFU mL -1 .
-
Acinetobacter lactucae sp. nov., isolated from iceberg lettuce (Asteraceae: Lactuca sativa)
USDA-ARS?s Scientific Manuscript database
Strain NRRL B-41902 and three closely related strains were isolated from iceberg lettuce. The strain was found to consist of strictly aerobic, gram-negative rods that formed cocci in late stationary phase. Subsequent to sequencing the 16S ribosomal RNA gene, it was found that strain NRRL B-41902 was...
-
Greene, C; Wu, J; Rickard, A H; Xi, C
2016-10-01
The human opportunistic pathogen, Acinetobacter baumannii, has the propensity to form biofilms and frequently cause medical device-related infections in hospitals. However, the physio-chemical properties of medical surfaces, in addition to bacterial surface properties, will affect colonization and biofilm development. The objective of this study was to compare the ability of A. baumannii to form biofilms on six different materials common to the hospital environment: glass, porcelain, stainless steel, rubber, polycarbonate plastic and polypropylene plastic. Biofilms were developed on material coupons in a CDC biofilm reactor. Biofilms were visualized and quantified using fluorescent staining and imaged using confocal laser scanning microscopy (CLSM) and by direct viable cell counts. Image analysis of CLSM stacks indicated that the mean biomass values for biofilms grown on glass, rubber, porcelain, polypropylene, stainless steel and polycarbonate were 0·04, 0·26, 0·62, 1·00, 2·08 and 2·70 μm(3) /μm(2) respectively. Polycarbonate developed statistically more biofilm mass than glass, rubber, porcelain and polypropylene. Viable cell counts data were in agreement with the CLSM-derived data. In conclusion, polycarbonate was the most accommodating surface for A. baumannii ATCC 17978 to form biofilms while glass was least favourable. Alternatives to polycarbonate for use in medical and dental devices may need to be considered. In the hospital environment, Acinetobacter baumannii is one of the most persistent and difficult to control opportunistic pathogens. The persistence of A. baumannii is due, in part, to its ability to colonize surfaces and form biofilms. This study demonstrates that A. baumannii can form biofilms on a variety of different surfaces and develops substantial biofilms on polycarbonate - a thermoplastic material that is often used in the construction of medical devices. The findings highlight the need to further study the in
-
Richie, Daryl L.; Takeoka, Kenneth T.; Bojkovic, Jade; Metzger, Louis E.; Rath, Christopher M.; Sawyer, William S.; Wei, Jun-Rong; Dean, Charles R.
2016-01-01
The lipid A moiety of lipopolysaccharide (LPS) is the main constituent of the outer leaflet of the Gram-negative bacterial outer membrane (OM) and is essential in many Gram-negative pathogens. An exception is Acinetobacter baumannii ATCC 19606, where mutants lacking enzymes occurring early in lipid A biosynthesis (LpxA, LpxC or LpxD), and correspondingly lacking LPS, can grow. In contrast, we show here that LpxH, an enzyme that occurs downstream of LpxD in the lipid A biosynthetic pathway, is essential for growth in this strain. Multiple attempts to disrupt lpxH on the genome were unsuccessful, and when LpxH expression was controlled by an isopropyl β-d-1-thiogalactopyranoside (IPTG) inducible promoter, cell growth under typical laboratory conditions required IPTG induction. Mass spectrometry analysis of cells shifted from LpxH-induced to uninduced (and whose growth was correspondingly slowing as LpxH was depleted) showed a large cellular accumulation of UDP-2,3-diacyl-GlcN (substrate of LpxH), a C14:0(3-OH) acyl variant of the LpxD substrate (UDP-3-O-[(R)-3-OH-C14]-GlcN), and disaccharide 1-monophosphate (DSMP). Furthermore, the viable cell counts of the LpxH depleted cultures dropped modestly, and electron microscopy revealed clear defects at the cell (inner) membrane, suggesting lipid A intermediate accumulation was toxic. Consistent with this, blocking the synthesis of these intermediates by inhibition of the upstream LpxC enzyme using CHIR-090 abrogated the requirement for IPTG induction of LpxH. Taken together, these data indicate that LpxH is essential for growth in A. baumannii ATCC19606, because, unlike earlier pathway steps like LpxA or LpxC, blockage of LpxH causes accumulation of detergent-like pathway intermediates that prevents cell growth. PMID:27526195
-
Stürenburg, Enno; Lang, Melanie; Horstkotte, Matthias A; Laufs, Rainer; Mack, Dietrich
2004-11-01
We aimed to assess the performance of the MicroScan ESBL plus confirmation panel using a series of 87 oxyimino-cephalosporin-resistant Gram-negative bacilli of various species. Organisms tested included 57 extended-spectrum beta-lactamase (ESBL) strains comprising Enterobacter aerogenes (3), Enterobacter cloacae (10), Escherichia coli (11), Klebsiella pneumoniae (26), Klebsiella oxytoca (3) and Proteus mirabilis (4). Also included were 30 strains resistant to oxyimino cephalosporins but lacking ESBLs, which were characterized with other resistance mechanisms, such as inherent clavulanate susceptibility in Acinetobacter spp. (4), hyperproduction of AmpC enzyme in Citrobacter freundii (2), E. aerogenes (3), E. cloacae (3), E. coli (4), Hafnia alvei (1) and Morganella morganii (1), production of plasmid-mediated AmpC beta-lactamase in K. pneumoniae (3) and E. coli (3) or hyperproduction of K1 enzyme in K. oxytoca (6). The MicroScan MIC-based clavulanate synergy correctly classified 50 of 57 ESBL strains as ESBL-positive and 23 of 30 non-ESBL strains as ESBL-negative (yielding a sensitivity of 88% and a specificity of 76.7%, respectively). False negatives among ESBL producers were highest with Enterobacter spp. due to masking interactions between ESBL and AmpC beta-lactamases. False-positive classifications occurred in two Acinetobacter spp., one E. coli producing plasmid-mediated AmpC beta-lactamase and two K. oxytoca hyperproducing their chromosomal K1 beta-lactamase. The MicroScan clavulanate synergy test proved to be a valuable tool for ESBL confirmation. However, this test has limitations in detecting ESBLs in Enterobacter spp. and in discriminating ESBL-related resistance from the K1 enzyme and from inherent clavulanate susceptibility in Acinetobacter spp.
-
Kvasnikov, E I; Gavrilenko, M N; Sumnevich, V G; Stepaniuk, V V; Eluseeva, G S; Stognii, I P
1977-01-01
A large number of bacterial strains assimilating chemical ethanol has been isolated using an original technique. Active growth of strains belonging to the genera Pseudomonas and, particularly, Acinetobacter was registered on mineral media containing ethanol. A mathematical model was constructed select a strain of Acinetobacter calcoaceticus K-9 during its continuous cultivation on media containing ethanol. The model makes it possible to determine conditions for producing a present amount of the biomass, the percentage of its yield, and the produc;iveness as a function of the dilution rate, temperature, and the concentration of ethanol and phosphoric acid in the medium. The main characteristics of the growth process in the studied factor space were established. The optimum conditions were calculated for growth of the strain with respect to each of the criteria. Under various conditions of bacterial growth, changes in the morphology and ultra-fine structure of the cells correlated with their physiological activity. The volume of the cells increased with the rate of dilution of the medium: the process can be described by a saturation curve. The presence of mesosomal structures is typical of the cells growing at low flow rates.
-
Guth, C; Cavalli, Z; Pernod, C; Lhopital, C; Wey, Pf; Gerome, P; Turc, J
2016-01-01
to describe the management and control of a limited outbreak of carbapenem-resistant Acinetobacter baumanii (CRAB) outbreak in a French intensive care unit. Careful review of the contact's and carrier's files and outbreak management procedures. An undiagnosed CRAB carrier was admitted to our intensive care unit after medical evacuation from Turkey. Despite preventive isolation and contact precautions, a secondary case was diagnosed 5 days after admission of the index case and resulted in the creation of a crisis unit. Prompt management included an epidemiologic investigation with contact screening and follow-up, environmental screening, and additional restrictive measures: isolation room, closure of adjacent rooms, patient cohorting with designated nurses, and reinforcement of contact precautions. restrictive management of CRAB outbreaks may allow prompt outbreak control and avoid prolonged room closures.
-
Daur, Ihsanullah; Saad, Maged M; Eida, Abdul Aziz; Ahmad, Shakeel; Shah, Zahid Hussain; Ihsan, Muhammad Z; Muhammad, Yasir; Sohrab, Sayed S; Hirt, Heribert
2018-01-01
This study focused on rhizobacteria to promote sustainable crop production in arid regions of Saudi Arabia. The study isolated 17 tightly root-adhering rhizobacteria from various plants at Hada Al Sham in Saudi Arabia. All 17 rhizobacterial isolates were confirmed as plant growth promoting rhizobacteria by classical biochemical tests. Using 16S rDNA gene sequence analyses, the strains were identified as Bacillus, Acinetobacter and Enterobacter . Subsequently, the strains were assessed for their ability to improve the physiology, nutrient uptake, growth, and yield of alfalfa plants grown under desert agriculture conditions. The field trials were conducted in a randomized complete block design. Inoculation of alfalfa with any of these 17 strains improved the relative water content; chlorophyll a; chlorophyll b; carotenoid contents; nitrogen (N), phosphorus, and potassium contents; plant height; leaf-to-stem ratio; and fresh and dry weight. Acinetobacter pittii JD-14 was most effective to increase fresh and dry weight of alfalfa by 41 and 34%, respectively, when compared to non-inoculated control plants. Nevertheless, all strains enhanced crop traits when compared to controls plants, indicating that these desert rhizobacterial strains could be used to develop an eco-friendly biofertilizer for alfalfa and possibly other crop plants to enhance sustainable production in arid regions.
-
Daur, Ihsanullah; Saad, Maged M.; Eida, Abdul Aziz; Ahmad, Shakeel; Shah, Zahid Hussain; Ihsan, Muhammad Z.; Muhammad, Yasir; Sohrab, Sayed S.; Hirt, Heribert
2018-01-01
This study focused on rhizobacteria to promote sustainable crop production in arid regions of Saudi Arabia. The study isolated 17 tightly root-adhering rhizobacteria from various plants at Hada Al Sham in Saudi Arabia. All 17 rhizobacterial isolates were confirmed as plant growth promoting rhizobacteria by classical biochemical tests. Using 16S rDNA gene sequence analyses, the strains were identified as Bacillus, Acinetobacter and Enterobacter. Subsequently, the strains were assessed for their ability to improve the physiology, nutrient uptake, growth, and yield of alfalfa plants grown under desert agriculture conditions. The field trials were conducted in a randomized complete block design. Inoculation of alfalfa with any of these 17 strains improved the relative water content; chlorophyll a; chlorophyll b; carotenoid contents; nitrogen (N), phosphorus, and potassium contents; plant height; leaf-to-stem ratio; and fresh and dry weight. Acinetobacter pittii JD-14 was most effective to increase fresh and dry weight of alfalfa by 41 and 34%, respectively, when compared to non-inoculated control plants. Nevertheless, all strains enhanced crop traits when compared to controls plants, indicating that these desert rhizobacterial strains could be used to develop an eco-friendly biofertilizer for alfalfa and possibly other crop plants to enhance sustainable production in arid regions. PMID:29670582
-
Ali, Hayssam M; Salem, Mohamed Z M; El-Shikh, Mohamed S; Megeed, Ahmed Abdel; Alogaibi, Yahya A; Talea, Ibrahim Ahmed
2017-01-01
Multidrug-resistant (MDR) Acinetobacter baumannii infections are a great public health concern and demand continuous surveillance and antibiotic stewardship. Virulence traits and the pathogenicity of Acinetobacter are less studied compared with the molecular epidemiological and antibiotic resistance profile of this organism. In our present study, we investigated the primary characteristics contributing to the virulence of MDR A. baumannii isolates and compared them with avirulent isolates. A total of 32 well-characterized MDR A. baumannii clinical isolates and 22 avirulent isolates from a healthy individual were subjected to multilocus sequence typing and polymerase chain reaction (PCR) for a variety of biofilm-associated genes. Additionally, a number of in vitro tests were performed to determine virulence properties. Isolates were found to relate to six sequence types (STs) in which the dominant sequence was ST557 in clinical isolates, followed by ST195 and ST208. However, ST557 and ST222 were absent in avirulent isolates. All STs belonged to clonal complex 2 and clonal lineage 2, which is considered to be a universal clone. PCR analysis showed that most clinical isolates were positive for biofilm-forming genes, such as csu and bap, and also carried pga and ompA genes, which were less common in avirulent isolates. Biofilm formation, phospholipase C production, hemolytic activity, and acinetobactin production occurred significantly more frequently in clinical isolates compared with avirulent isolates. Though A. baumannii clonal lineages showed common virulence traits, they differed in virulent phenotype expression. These findings further support previous studies indicating that A. baumannii is a versatile pathogen with an ability to acquire iron and survive in iron-limiting conditions, highlighting the acinetobactin-mediated iron acquisition mechanisms involved in the pathogenesis of A. baumannii infections.
-
Biedenbach, Douglas J; Giao, Phan Trong; Hung Van, Pham; Su Minh Tuyet, Nguyen; Thi Thanh Nga, Tran; Phuong, Doan Mai; Vu Trung, Nguyen; Badal, Robert E
2016-09-01
Multidrug-resistant bacterial pathogens are becoming a significant problem worldwide. Acinetobacter baumannii and Pseudomonas aeruginosa are problematic multidrug-resistant pathogens. This multicenter study in Vietnam determined the level of resistance to antimicrobial agents used to treat A baumannii and P aeruginosa infections in this country. Five medical centers in Vietnam provided 529 P aeruginosa and 971 Acinetobacter species (904 A baumannii) isolates from patients with hospital-acquired or ventilator-associated pneumonia from 2012 to 2014. A central laboratory verified identification of the isolates and performed susceptibility testing using Clinical and Laboratory Standards Institute methods. Resistance to cephalosporins, β-lactam/β-lactamase inhibitors, carbapenems, and fluoroquinolones was >90% against A baumannii. Aminoglycosides had only slightly better activity, with amikacin resistance >80%. Only colistin (MIC90, ≤0.25 mg/L) and tigecycline (MIC90, 4 mg/L) had appreciable activity against A baumannii. Similar activity was observed among the β-lactams tested against P aeruginosa. Cefepime demonstrated the highest activity (60.1% susceptible), which was similar to doripenem (58.6% susceptible), the most active carbapenem tested. Amikacin was the most active aminoglycoside tested against P aeruginosa, with susceptibility of 81.7% compared with tobramycin (58.0%) and gentamicin (56.5%). Fluoroquinolones had limited activity against P aeruginosa with susceptibility to ciprofloxacin (55.0%). All P aeruginosa isolates had colistin MIC values ≤2 mg/L. The data from this 3-year longitudinal study in Vietnam demonstrate that 2 of the most common nonfermentative gram-negative pathogens associated with hospital-acquired and ventilator-associated pneumonia are significantly resistant to most of the available treatment options and require combination therapies unless new antimicrobial agents become available. Copyright © 2016. Published by Elsevier Inc.
-
The mazEF toxin-antitoxin system as a novel antibacterial target in Acinetobacter baumannii.
Ghafourian, Sobhan; Good, Liam; Sekawi, Zamberi; Hamat, Rukman Awang; Soheili, Sara; Sadeghifard, Nourkhoda; Neela, Vasanthakumari
2014-07-01
Although analysis of toxin-antitoxin (TA) systems can be instructive, to date, there is no information on the prevalence and identity of TA systems based on a large panel of Acinetobacter baumannii clinical isolates. The aim of the current study was to screen for functional TA systems among clinical isolates of A. baumannii and to identify the systems' locations. For this purpose, we screened 85 A. baumannii isolates collected from different clinical sources for the presence of the mazEF, relBE and higBA TA genes. The results revealed that the genes coding for the mazEF TA system were commonly present in all clinical isolates of A. baumannii. Reverse transcriptase-polymerase chain reaction analysis showed that transcripts were produced in the clinical isolates. Our findings showed that TA genes are prevalent, harboured by chromosomes and transcribed within A. baumannii. Hence, activation of the toxin proteins in the mazEF TA system should be investigated further as an effective antibacterial strategy against this bacterium.
-
Patel, G; Perez, F; Hujer, A M; Rudin, S D; Augustine, J J; Jacobs, G H; Jacobs, M R; Bonomo, R A
2015-04-01
Acinetobacter baumannii is an important cause of healthcare-associated infections, and is particularly problematic among patients who undergo organ transplantation. We describe a case of fulminant sepsis caused by carbapenem-resistant A. baumannii harboring the blaOXA-23 carbapenemase gene and belonging to international clone II. This isolate led to the death of a patient 6 days after simultaneous kidney-pancreas transplantation. Autopsy findings revealed acute mitral valve endocarditis, myocarditis, splenic and renal emboli, peritonitis, and pneumonia. This case highlights the severe nature of certain A. baumannii infections and the vulnerability of transplanted patients to the increasingly intractable "high-risk" clones of multidrug-resistant organisms. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
-
Elhosseiny, Noha M; Amin, Magdy A; Yassin, Aymen S; Attia, Ahmed S
2015-01-01
Acinetobacter baumannii is one of the most significant threats to global public health. This threat is compounded by the fact that A. baumannii is rapidly becoming resistant to all relevant antimicrobials. Identifying key microbial factors through which A. baumannii resists hostile host environment is paramount to the development of novel antimicrobials targeting infections caused by this emerging pathogen. An attractive target could be a molecule that plays a role in the pathogenesis and stress response of A. baumannii. Accordingly, the universal stress protein A (UspA) was chosen to be fully investigated in this study. A platform of A. baumannii constructs, expressing various levels of the uspA gene ranging from zero to thirteen folds of wild-type level, and a recombinant E. coli strain, were employed to investigate the role of UspA in vitro stress and in vivo pathogenesis. The UspA protein plays a significant role in protecting A. baumannii from H(2)O(2), low pH, and the respiratory toxin 2,4-DNP. A. baumannii UspA protein plays an essential role in two of the deadliest types of infection caused by A. baumannii; pneumonia and sepsis. This distinguishes A. baumannii UspA from its closely related homolog, the Staphylococcus aureus Usp2, as well as from the less similar Burkholderia glumae Usps. Heterologous and overexpression experiments suggest that UspA mediates its role via an indirect mechanism. Our study highlights the role of UspA as an important contributor to the A. baumannii stress and virulence machineries, and polishes it as a plausible target for new therapeutics. Copyright © 2014 Elsevier GmbH. All rights reserved.
-
Carbapenem-Resistant Acinetobacter baumannii and Enterobacteriaceae in South and Southeast Asia
Apisarnthanarak, Anucha; Khan, Erum; Ghafur, Abdul
2016-01-01
SUMMARY Carbapenem-resistant Gram-negative bacteria, in particular the Acinetobacter baumannii-calcoaceticus complex and Enterobacteriaceae, are escalating global public health threats. We review the epidemiology and prevalence of these carbapenem-resistant Gram-negative bacteria among countries in South and Southeast Asia, where the rates of resistance are some of the highest in the world. These countries house more than a third of the world's population, and several are also major medical tourism destinations. There are significant data gaps, and the almost universal lack of comprehensive surveillance programs that include molecular epidemiologic testing has made it difficult to understand the origins and extent of the problem in depth. A complex combination of factors such as inappropriate prescription of antibiotics, overstretched health systems, and international travel (including the phenomenon of medical tourism) probably led to the rapid rise and spread of these bacteria in hospitals in South and Southeast Asia. In India, Pakistan, and Vietnam, carbapenem-resistant Enterobacteriaceae have also been found in the environment and community, likely as a consequence of poor environmental hygiene and sanitation. Considerable political will and effort, including from countries outside these regions, are vital in order to reduce the prevalence of such bacteria in South and Southeast Asia and prevent their global spread. PMID:27795305
-
Selçuk, Caferi Tayyar; Durgun, Mustafa; Ozalp, Burhan; Tekin, Alicem; Tekin, Recep; Akçay, Cemal; Alabalık, Ulaş
2012-12-01
In this study, our aim is to compare the efficacy of different topical antibacterial agents in a rat model contaminated with a multi drug resistant (MDR) standard Acinetobacter baumannii strain. The study was carried out on 40 Sprague-Dawley rats of 250-300 g each. For the purposes of this study, the rats were divided into 5 groups, with 8 rats in each group: Group 1 control; Group 2 silver sulfadiazine; Group 3 mupirocin; Group 4 Acticoat group; and Group 5 octenidine dihydrochloride group. Following to the formation of the full-thickness burn areas in rats, the MDR A. baumannii standard strain was inoculated into the burned area. The rats in all the groups were sacrificed at the end of the 10th day and subjected to histopathological and microbiological evaluation. In the histopathological evaluation, the lowest inflammatory cell response and bacterial density in the eschar and muscle tissues were observed in the Acticoat group. While these results were found to be statistically significant compared to the silver sulfadiazine group, only the bacterial density in the muscle tissue was found as significant in comparison to the mupirocin and octenidine groups. In the microbiological evaluation, the lowest growth in the muscle tissue culture among all the groups was observed in the Acticoat group. The growth in the eschar tissue culture was significantly lower in the Acticoat and octenidine groups in comparison to the silver sulfadiazine group. At the end of the study, it has been observed that Acticoat was effective both in eschar and muscle, while octenidine was effective in eschar tissues in a rat burn model contaminated with MDR A. baumannii. Copyright © 2012 Elsevier Ltd and ISBI. All rights reserved.
-
Delgado Naranjo, Jesús; Villate Navarro, José Ignacio; Sota Busselo, Mercedes; Martínez Ruíz, Alberto; Hernández Hernández, José María; Torres Garmendia, María Pilar; Urcelay López, María Isabel
2013-01-01
Background. Between July 2009 and September 2010, an outbreak of multidrug-resistant (MDR) Acinetobacter baumannii was detected in one critical care unit of a tertiary hospital in the Basque Country, involving 49 infected and 16 colonized patients. The aim was to evaluate the impact of environmental cleaning and systematic sampling from environmental objects on the risk of infection by MDR A. baumannii. Methods. After systematic sampling from environmental objects and molecular typing of all new MDR A. baumannii strains from patients and environmental isolates, we analyzed the correlation (Pearson's r) between new infected cases and positive environmental samples. The risk ratio (RR) of infection was estimated with Poisson regression. Results. The risk increased significantly with the number of positive samples in common areas (RR = 1.40; 95%CI = 0.99-1.94) and positive samples in boxes (RR = 1.19; 95%CI = 1.01-1.40). The number of cases also positively correlated with positive samples in boxes (r = 0.50; P < 0.05) and common areas (r = 0.29; P = 0.18). Conclusion. Once conventional measures have failed, environmental cleaning, guided by systematic sampling from environmental objects, provided the objective risk reduction of new cases and enabled the full control of the outbreak.
-
Characterization of Acinetobacter baumannii biofilm associated components
NASA Astrophysics Data System (ADS)
Brossard, Kari A.
Acinetobacter baumannii is a Gram-negative aerobic coccobaccillus that is a major cause of nosocomial infections worldwide. Infected individuals may develop pneumonia, urinary tract, wound, and other infections that are associated with the use of indwelling medical devices such as catheters and mechanical ventilation. Treatment is difficult because many A. baumannii isolates have developed multi-drug resistance and the bacterium can persist on abiotic surfaces. Persistence and resistance may be due to formation of biofilms, which leads to long-term colonization, evasion of the host immune system and resistance to treatment with antibiotics and disinfectants. While biofilms are complex multifaceted structures, two bacterial components that have been shown to be important in formation and stability are exopolysaccharides (EPS) and the biofilm-associated protein (Bap). An EPS, poly-beta-1,6-N-acetylglucosamine, PNAG, has been described for E. coli and S. epidermidis. PNAG acts as an intercellular adhesin. Production of this adhesin is dependent on the pga/icaABCD locus. We have identified a homologous locus in A. baumannii 307-0294 that is involved in production of an exopolysaccharide, recognized by an anti-PNAG antibody. We hypothesized that the A. baumannii pgaABCD locus plays a role in biofilm formation, and protection against host innate defenses and disinfectants suggesting that PNAG is a possible virulence factor for the organism. The first aim of this thesis will define the pgaABCD locus. We have previously identified Bap, a protein with similarity to those described for S. aureus and we have demonstrated that this protein is involved in maintaining the stability of biofilms on glass. We hypothesized that A. baumannii Bap plays a role in persistence and pathogenesis and is regulated by quorum sensing. In our second aim we will examine the role of Bap in attachment and biofilm formation on medically relevant surfaces and also determine if Bap is involved in
-
Lertsrisatit, Yongyut; Santimaleeworagun, Wichai; Thunyaharn, Sudaluck; Traipattanakul, Jantima
2017-01-01
Colistin is a drug of last resort for treating multidrug-resistant Acinetobacter baumannii infections. Unfortunately, colistin-resistant A. baumannii (CoR-AB) has been reported. Here, we examined the in vitro effect of mono- and combined antimicrobials against CoR-AB strains and their resistance mechanism, and evaluated the clinical outcomes of CoR-AB-infected patients. Seventeen clinical CoR-AB strains were isolated from patients at Phramongkutklao hospital, 2011-2015. The mono- and synergistic activities of colistin, tigecycline, sulbactam, imipenem, meropenem, amikacin, fosfomycin, and cotrimoxazole were examined by minimum inhibitory concentration (MIC) and fractional inhibitory concentration index. Clonal relationship and resistance genes were determined by repetitive extragenic palindromic polymerase chain reaction with specific primers. The effect of carbonyl cyanide 3-chlorophenylhydrazone combined with colistin was used to test efflux pump involvement. Patient treatment outcomes were also reported. The most prevalent infection in CoR-AB patients was pneumonia (35.3%), and all patients were administered colistin combined with another agent. The 30-day mortality was 70.6%, and the colistin MIC range and MIC50 was 16-512 μg/mL and 64 μg/mL, respectively. All CoR-AB strains were sensitive to tigecycline. Sporadic isolates were susceptible to sulbactam, imipenem, meropenem, and cotrimoxazole. A synergistic or additive effect was observed for colistin plus imipenem or meropenem (16.7%), sulbactam (66.7%), or tigecycline (66.7%). The CoR-AB isolates could be divided into four different clones (A-D) with a high prevalence of group B (47.1%). Eight isolates harbored blaOXA23, blaIMP , blaKPC , and blaNDM , and one contained blaOXA23 , blaIMP , and blaKPC , while the eight remaining isolates carried only blaOXA23 . The MIC values of all strains were greatly reduced for colistin plus carbonyl cyanide 3-chlorophenylhydrazone. CoR-AB clinical isolates exhibited very
-
Turano, Helena; Gomes, Fernando; Medeiros, Micheli; Oliveira, Silvane; Fontes, Lívia C; Sato, Maria I Z; Lincopan, Nilton
2016-09-01
This study reports the presence of hospital-associated high-risk lineages of OXA-23-producing ST79 Acinetobacter baumannii and SPM-1-producing ST277 Pseudomonas aeruginosa in urban rivers in Brazil. These findings indicate that urban rivers can act as reservoirs of clinically important multidrug-resistant bacteria, which constitute a potential risk to human and animal health. Copyright © 2016 Elsevier Inc. All rights reserved.
-
Kushwaha, Anamika; Rani, Radha; Kumar, Sanjay; Thomas, Tarence; David, Arun Alfred; Ahmed, Meraz
2017-04-01
A lead-resistant bacterial strain was isolated from coal mine dump and identified as Acinetobacter junii Pb1 on basis of 16S rRNA (ribosomal ribonucleic acid) gene sequencing. The minimum inhibitory concentration of lead for the strain was 16,000 mg l -1 and it showed antibiotic and multi metal resistance. In aqueous culture, at an initial lead (Pb(II)) concentration of 100 and 500 mg l -1 , lead adsorption and accumulation by the isolate was 100 and 60%, at pH 7 at 30 °C after 48 and 120 h, respectively. The two fractions of exopolysaccharide (EPS), loosely associated EPS (laEPS) and bound EPS (bEPS), and whole cells (devoid of EPS) showed high binding affinity towards Pb(II). The binding affinity of laEPS towards Pb(II) (1071 mg Pb g -1 ) was three times higher than that of bEPS (321.5 mg Pb g -1 ) and 6.5 times higher than that of whole cells (165 mg Pb g -1 ). The binding affinity of EPS and whole cells with Pb(II), reported in the current study, is considerably higher as compared to that reported in the literature, till date. SEM analysis, showed an increase in thickness of cells on exposure to Pb(II) and TEM analysis, revealed its accumulation (interior of cell) and its adsorption (with the external cell surface). The isolate was also found to be positive for indole acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production which helps in promoting plant growth. Thus, this study provides a new understanding towards Pb(II) uptake by A. junii Pb1, highlighting its potential on the restoration of Pb(II) contaminated repositories.
-
Tsai, Chin-Chuan; Lin, Chi-Shiuan; Hsu, Chun-Ru; Chang, Chiu-Ming; Chang, I-Wei; Lin, Li-Wei; Hung, Chih-Hsin; Wang, Jiun-Ling
2018-03-20
No animal model studies have been conducted in which the efficacy of herbal compounds has been tested against multidrug-resistant Acinetobacter baumannii infections. Very few antibiotics are available for the treatment of pulmonary infections caused by extensively drug-resistant Acinetobacter baumannii (XDRAB). To find alternative treatments, traditional Chinese herbs were screened for their antimicrobial potential. The present study screened 30 herbs that are traditionally used in Taiwan and that are commonly prescribed for heat clearing and detoxification. The herbs with antibacterial activities were analysed by disc diffusion assays, time-kill assays and a murine lung infection model. Of the 30 herbs tested, only Scutellaria barbata demonstrated 100% in vitro activity against XDRAB. Furthermore, we compared the antibacterial effect of the S. barbata extract with that of colistin, and the S. barbata extract showed better antibacterial effect. In the XDRAB pneumonia murine model, we compared the antimicrobial effects of the orally administered S. barbata extract (200 mg/kg, every 24 h), the intratracheally administered colistin (75,000 U/kg, every 12 h), and the control group. The bacterial load in the lungs of the treatment group that received the oral S. barbata extract showed a significant decrease in comparison to that in the lungs of the control group. In addition, histopathological examinations also revealed better resolution of perivascular, peribronchial, and alveolar inflammation in the oral S. barbata extract-treated group. Our in vitro and in vivo data from the animal model support the use of S. barbata as an alternate drug to treat XDRAB pulmonary infections. However, detailed animal studies and clinical trials are necessary to establish the clinical utility of S. barbata in treating XDRAB pulmonary infections.
-
Giovannini, Pier Paolo; Grandini, Alessandro; Perrone, Daniela; Pedrini, Paola; Fantin, Giancarlo; Fogagnolo, Marco
2008-12-22
We report the very efficient biotransformation of cholic acid to 7-keto- and 7,12-diketocholic acids with Acinetobacter calcoaceticus lwoffii. The enzymes responsible of the biotransformation (i.e. 7alpha- and 12alpha-hydroxysteroid dehydrogenases) are partially purified and employed in a new chemo-enzymatic synthesis of ursodeoxycholic acid starting from cholic acid. The first step is the 12alpha-HSDH-mediated total oxidation of sodium cholate followed by the Wolf-Kishner reduction of the carbonyl group to chenodeoxycholic acid. This acid is then quantitatively oxidized with 7alpha-HSDH to 7-ketochenodeoxycholic acid, that was chemically reduced to ursodeoxycholic acid (70% overall yield).
-
Tada, Tatsuya; Shrestha, Shovita; Shimada, Kayo; Ohara, Hiroshi; Sherchand, Jeevan B; Pokhrel, Bharat M; Kirikae, Teruo
2017-03-01
A novel PER-type extended-spectrum β-lactamase, PER-8, was identified in an Acinetobacter baumannii clinical isolate obtained in Nepal. The amino acid sequence of PER-8 has a substitution at position 39 (Gly to Glu) compared with that of PER-7. The k cat / K m ratio of PER-8 for aztreonam was lower than that of PER-7, while the k cat / K m ratio of PER-8 for imipenem was higher than that of PER-7. The genomic environment surrounding bla PER-8 was intI1 bla PSE-1 qacEDI sulI IS CR1-bla PER-8 gts sulI orfX on a 100-kb plasmid. Copyright © 2017 American Society for Microbiology.
-
Survey of metal tolerance in moderately halophilic eubacteria.
Nieto, J J; Fernández-Castillo, R; Márquez, M C; Ventosa, A; Quesada, E; Ruiz-Berraquero, F
1989-01-01
The tolerance patterns, expressed as MICs, for 250 moderately halophilic eubacteria to 10 heavy metals were surveyed by using an agar dilution method. The moderate halophiles tested included 12 culture collection strains and fresh isolates representative of Deleya halophila (37 strains), Acinetobacter sp. (24 strains), Flavobacterium sp. (28 strains), and 149 moderately halophilic gram-positive cocci included in the genera Marinococcus, Sporosarcina, Micrococcus, and Staphylococcus. On the basis of the MICs, the collection strains showed, overall, similar responses to silver, cobalt, mercury, nickel, lead, and zinc. All were sensitive to silver, mercury, and zinc and tolerant of lead. The response to arsenate, cadmium, chromium, and copper was very heterogeneous. The metal susceptibility levels of the 238 freshly isolated strains were, in general, very heterogeneous among the four taxonomic groups as well as within the strains included in each group. The highest toxicities were found with mercury, silver, and zinc, while arsenate showed the lowest activity. All these strains were tolerant of nickel, lead, and chromium and sensitive to silver and mercury. Acinetobacter sp. strains were the most heavy-metal tolerant, with the majority of them showing tolerance of eight different metal ions. In contrast, Flavobacterium sp. strains were the most metal sensitive. The influence of salinity and yeast extract concentrations of the culture medium on the toxicity of the heavy metals tested for some representative strains was also studied. Lowering the salinity, in general, led to enhanced sensitivity to cadmium and, in some cases, to cobalt and copper. However, increasing the salinity resulted in only a slight decrease in the cadmium, copper, and nickel toxicities.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2802612
-
Survey of metal tolerance in moderately halophilic eubacteria.
Nieto, J J; Fernández-Castillo, R; Márquez, M C; Ventosa, A; Quesada, E; Ruiz-Berraquero, F
1989-09-01
The tolerance patterns, expressed as MICs, for 250 moderately halophilic eubacteria to 10 heavy metals were surveyed by using an agar dilution method. The moderate halophiles tested included 12 culture collection strains and fresh isolates representative of Deleya halophila (37 strains), Acinetobacter sp. (24 strains), Flavobacterium sp. (28 strains), and 149 moderately halophilic gram-positive cocci included in the genera Marinococcus, Sporosarcina, Micrococcus, and Staphylococcus. On the basis of the MICs, the collection strains showed, overall, similar responses to silver, cobalt, mercury, nickel, lead, and zinc. All were sensitive to silver, mercury, and zinc and tolerant of lead. The response to arsenate, cadmium, chromium, and copper was very heterogeneous. The metal susceptibility levels of the 238 freshly isolated strains were, in general, very heterogeneous among the four taxonomic groups as well as within the strains included in each group. The highest toxicities were found with mercury, silver, and zinc, while arsenate showed the lowest activity. All these strains were tolerant of nickel, lead, and chromium and sensitive to silver and mercury. Acinetobacter sp. strains were the most heavy-metal tolerant, with the majority of them showing tolerance of eight different metal ions. In contrast, Flavobacterium sp. strains were the most metal sensitive. The influence of salinity and yeast extract concentrations of the culture medium on the toxicity of the heavy metals tested for some representative strains was also studied. Lowering the salinity, in general, led to enhanced sensitivity to cadmium and, in some cases, to cobalt and copper. However, increasing the salinity resulted in only a slight decrease in the cadmium, copper, and nickel toxicities.(ABSTRACT TRUNCATED AT 250 WORDS)
-
Di Bonaventura, Ivan; Baeriswyl, Stéphane; Capecchi, Alice; Gan, Bee-Ha; Jin, Xian; Siriwardena, Thissa N; He, Runze; Köhler, Thilo; Pompilio, Arianna; Di Bonaventura, Giovanni; van Delden, Christian; Javor, Sacha; Reymond, Jean-Louis
2018-05-15
We used the concept of chemical space to explore a virtual library of bicyclic peptides formed by double thioether cyclization of a precursor linear peptide, and identified an antimicrobial bicyclic peptide (AMBP) with remarkable activity against several MDR strains of Acinetobacter baumannii and Pseudomonas aeruginosa.
-
Das, Joyati; Sarkar, Priyabrata
2018-05-15
Arsenic, a carcinogenic and toxic contaminant of soil and water, affects human health adversely. During last few decades, it has been an important global environmental issue. Among several arsenic detoxification methods remediation using arsenic resistant microbes is proved to be environment-friendly and cost-effective. This study aimed to test the effects of arsenic utilizing bacterial strain Acinetobacter lwoffii (RJB-2) on arsenic uptake and growth of mung bean plants (Vigna radiata). RJB-2 exhibited tolerance up to 125mM of arsenic (V) and 50mM of arsenic (III). RJB-2 produced plant growth promoting substances e.g. indole acetic acid (IAA), siderophores, exopolysaccharide (EPS) and phosphate solubilization in the absence and in presence of arsenic. Pot experiments were used to scrutinize the role of RJB-2 on arsenic uptake and growth of mung bean plants grown in soil amended with 22.5mgkg -1 of sodium arsenate (Na 2 HAsO 4 ·7H 2 O). RJB-2 could arrest arsenic uptake in just 7days and increase plant growth, number of plants per pot, chlorophyll and carotenoid content of the mung bean plants. RJB-2 formed biofilm and its root-association helped to abate arsenic uptake in mung bean. Confocal and light microscopic studies also revealed the abatement of arsenic uptake and increase in chlorophyll content in mung bean plants in presence of RJB-2. RJB-2 was also responsible for less production of reactive oxygen species (ROS) in mung bean plants reducing the oxidative damage caused by arsenic. The lower percentage of electrolytic leakage (EL) in RJB-2 inoculated mung bean plants proved arsenic abatement. The study also reported the distribution of arsenic in various parts of mung bean plant. RJB-2 owing to its intrinsic abilities of plant growth promotion even in presence of high concentrations of arsenic could inhibit arsenic uptake completely and therefore it could be used in large-scale cultivation for phytostabilization of plants. Copyright © 2017 Elsevier B
-
Characterization of a high-affinity iron transport system in Acinetobacter baumannii.
Echenique, J R; Arienti, H; Tolmasky, M E; Read, R R; Staneloni, R J; Crosa, J H; Actis, L A
1992-01-01
Analysis of a clinical isolate of Acinetobacter baumannii showed that this bacterium was able to grow under iron-limiting conditions, using chemically defined growth media containing different iron chelators such as human transferrin, ethylenediaminedi-(o-hydroxyphenyl)acetic acid, nitrilotriacetic acid, and 2,2'-bipyridyl. This iron uptake-proficient phenotype was due to the synthesis and secretion of a catechol-type siderophore compound. Utilization bioassays using the Salmonella typhimurium iron uptake mutants enb-1 and enb-7 proved that this siderophore is different from enterobactin. This catechol siderophore was partially purified from culture supernatants by adsorption chromatography using an XAD-7 resin. The purified component exhibited a chromatographic behavior and a UV-visible light absorption spectrum different from those of 2,3-dihydroxybenzoic acid and other bacterial catechol siderophores. Furthermore, the siderophore activity of this extracellular catechol was confirmed by its ability to stimulate energy-dependent uptake of 55Fe(III) as well as to promote the growth of A. baumannii bacterial cells under iron-deficient conditions imposed by 60 microM human transferrin. Polyacrylamide gel electrophoresis analysis showed the presence of iron-regulated proteins in both inner and outer membranes of this clinical isolate of A. baumannii. Some of these membrane proteins may be involved in the recognition and internalization of the iron-siderophore complexes. Images PMID:1447137
-
Management of an Acinetobacter baumannii outbreak in an intensive care unit.
Tanguy, M; Kouatchet, A; Tanguy, B; Pichard, É; Fanello, S; Joly-Guillou, M-L
2017-10-01
Acinetobacter baumannii is a ubiquitous pathogen resistant to desiccation and responsible for healthcare-associated infections (HAI), especially in intensive care units (ICU) where it is responsible for 5-10% of HAIs. An A. baumannii outbreak occurred in the ICU of the University Hospital of Angers, France. To describe the A. baumannii outbreak and to evaluate the control measures taken. The secondary objective was to evaluate the impact of the electronic alert system on the incidence of multidrug resistance to antibiotics. We performed a descriptive study of A. baumannii carriers during the outbreak. Case contacts and carriers were described using the epidemic curve and a case synopsis table. From August 2011 to September 2013, 49 patients presenting with an extended-spectrum beta-lactamase-producing A. baumannii infection were identified: thirty-four were colonized and 15 were infected. No death was due to the outbreak. Measures taken were: geographical and technical isolation of patients, dedicated team implementation, contact precaution implementation including hand hygiene measures, appropriate use of gloves, and reinforcement of bio-cleaning procedures. Some patients were re-admitted to hospital while still being carriers; this could explain epidemic peaks. The immersion mission of the hygiene nurse contributed to answering healthcare workers' queries and led to a better cooperation between the ICU and the hygiene team. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
-
Manian, Farrin A; Griesnauer, Sandra; Senkel, Diane
2013-04-01
Quantitative broth cultures were obtained from hospital rooms newly vacated by patients positive for multidrug-resistant Acinetobacter baumannii complex (ABC) before and after terminal cleaning and disinfection. Of 10 ABC-positive precleaned room surfaces, 6 (60%) remained culture-positive after terminal cleaning and disinfection. Of a total of 16 room surfaces with detectable ABC by the quantitative method, 5 (31.2%; 95% confidence interval, 13.9%-55.8%) were also culture-positive by the qualitative technique. Copyright © 2013 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.
-
Umezawa, Kazuo; Asai, Satomi; Ohshima, Toshio; Iwashita, Hideo; Ohashi, Maya; Sasaki, Mika; Kaneko, Akihiro; Inokuchi, Sadaki; Miyachi, Hayato
2015-11-01
An outbreak of amikacin- and ciprofloxacin-resistant Acinetobacter baumannii ST219 in Tokai University hospital's emergency intensive care unit was caused by its colonization in water systems and subsequent spread through oral care using tap water. The outbreak was successfully controlled after replacement of the water system and implementation as of daily cleaning of water taps and oral care with a dry method. It is important to strictly manage the water system in critical care areas. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
-
Mutai, Collins; Njuguna, Joyce; Ghimire, Sita
2017-10-01
Endophytic and plant-associated bacteria were isolated from plants and rhizoplane soil of naturally grown Brachiaria grasses at International Livestock Research Institute in Nairobi, Kenya. Eighty-four bacterial strains were isolated from leaf tissues, root tissues, and rhizoplane soil on nutrient agar and 869 media. All bacterial strains were identified to the lowest possible taxonomic unit using 16S rDNA primers and were characterized for the production of Indole-3-acetic acid, hydrogen cyanide, and ACC deaminase; phosphate solubilization; siderophore production; antifungal properties; and plant biomass production. The 16S rDNA-based identification grouped these 84 bacterial strains into 3 phyla, 5 classes, 8 orders, 12 families, 16 genera, and 50 unique taxa. The four most frequently isolated genera were Pseudomonas (23), Pantoea (17), Acinetobacter (9), and Enterobacter (8). The functional characterization of these strains revealed that 41 of 84 strains had a minimum of three plant beneficial properties. Inoculation of maize seedlings with Acinetobacter spp., Microbacterium spp., Pectobacterium spp., Pseudomonas spp., and Enterobacter spp. showed positive effects on seedling biomass production. The ability of Brachiaria grasses to host genetically diverse bacteria, many of them with multiple plant growth-promoting attributes, might have contributed to high biomass production and adaptation of Brachiaria grasses to drought and low fertility soils. © 2017 International Livestock Research Institute. MicrobiologyOpen published by John Wiley & Sons Ltd.
-
NASA Astrophysics Data System (ADS)
Zhang, Qiuzhuo; Wang, Duanchao; Li, Mengmeng; Xiang, Wei-Ning; Achal, Varenyam
2014-03-01
Two indigenous bacteria of petroleum contaminated soil were characterized to utilize diesel fuel as the sole carbon and energy sources in this work. 16S rRNA gene sequence analysis identified these bacteria as Sphingomonas sp. and Acinetobacter junii. The ability to degrade diesel fuel has been demonstrated for the first time by these isolates. The results of IR analyses showed that Sphingomonas sp. VA1 and A. junii VA2 degraded up to 82.6% and 75.8% of applied diesel over 15 days, respectively. In addition, Sphingomonas sp. VA1 possessed the higher cellular hydrophobicities of 94% for diesel compared to 81% by A. junii VA2. The isolates Sphingomonas sp. VA1 and A. junii VA2 exhibited 24% and 18%, respectively emulsification activity. This study reports two new diesel degrading bacterial species, which can be effectively used for bioremediation of petroleum contaminated sites.
-
The Acinetobacter baumannii Oxymoron: Commensal Hospital Dweller Turned Pan-Drug-Resistant Menace
Roca, Ignasi; Espinal, Paula; Vila-Farrés, Xavier; Vila, Jordi
2012-01-01
During the past few decades Acinetobacter baumannii has evolved from being a commensal dweller of health-care facilities to constitute one of the most annoying pathogens responsible for hospitalary outbreaks and it is currently considered one of the most important nosocomial pathogens. In a prevalence study of infections in intensive care units conducted among 75 countries of the five continents, this microorganism was found to be the fifth most common pathogen. Two main features contribute to the success of A. baumannii: (i) A. baumannii exhibits an outstanding ability to accumulate a great variety of resistance mechanisms acquired by different mechanisms, either mutations or acquisition of genetic elements such as plasmids, integrons, transposons, or resistant islands, making this microorganism multi- or pan-drug-resistant and (ii) The ability to survive in the environment during prolonged periods of time which, combined with its innate resistance to desiccation and disinfectants, makes A. baumannii almost impossible to eradicate from the clinical setting. In addition, its ability to produce biofilm greatly contributes to both persistence and resistance. In this review, the pathogenesis of the infections caused by this microorganism as well as the molecular bases of antibacterial resistance and clinical aspects such as treatment and potential future therapeutic strategies are discussed in depth. PMID:22536199
-
Zhang, Yunsong; Zhu, Yingbo; Gupta, Asheesh; Huang, Yingying; Murray, Clinton K; Vrahas, Mark S; Sherwood, Margaret E; Baer, David G; Hamblin, Michael R; Dai, Tianhong
2014-06-15
In this study, we investigated the utility of antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model. A bioluminescent clinical isolate of multidrug-resistant A. baumannii was obtained. The susceptibility of A. baumannii to blue light (415 nm)-inactivation was compared in vitro to that of human keratinocytes. Repeated cycles of sublethal inactivation of bacterial by blue light were performed to investigate the potential resistance development of A. baumannii to blue light. A mouse model of third degree burn infected with A. baumannii was developed. A single exposure of blue light was initiated 30 minutes after bacterial inoculation to inactivate A. baumannii in mouse burns. It was found that the multidrug-resistant A. baumannii strain was significantly more susceptible than keratinocytes to blue light inactivation. Transmission electron microscopy revealed blue light-induced ultrastructural damage in A. baumannii cells. Fluorescence spectroscopy suggested that endogenous porphyrins exist in A. baumannii cells. Blue light at an exposure of 55.8 J/cm(2) significantly reduced the bacterial burden in mouse burns. No resistance development to blue light inactivation was observed in A. baumannii after 10 cycles of sublethal inactivation of bacteria. No significant DNA damage was detected in mouse skin by means of a skin TUNEL assay after a blue light exposure of 195 J/cm(2). © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.
-
Irfan, S; Turton, J F; Mehraj, J; Siddiqui, S Z; Haider, S; Zafar, A; Memon, B; Afzal, O; Hasan, R
2011-06-01
The purpose of this study was to identify molecular and epidemiological characteristics of hospital-acquired carbapenem-resistant Acinetobacter baumannii (CRAB) from two different intensive care unit (ICU) settings in Karachi, Pakistan. A cross-sectional study was performed in the adult ICUs of a private sector tertiary care hospital (PS-ICU) and of a government sector hospital (GS-ICU) between November 2007 and August 2008. Deduplicated CRAB isolates from clinical specimens were examined for carbapenemase and class 1 integrase genes. Isolates were typed using sequence-based multiplex polymerase chain reaction, pulsed-field gel electrophoresis (PFGE) and variable number tandem repeat (VNTR). A total of 50 patients (33 from PS-ICU and 17 from GS-ICU) were recruited. There were statistically significant differences between patients in the two ICUs in terms of mean age, comorbidities, the presence of central venous pressure lines, urinary catheters, and average length of stay. bla(OxA-23-like) acquired-oxacillinase genes were found in 47/50 isolates. Class 1 integrase genes were found in 50% (25/50) of the organisms. The majority of isolates belonged to strains of European clones I and II. PFGE typing grouped the isolates into eight distinct clusters, three of which were found in both hospitals. Most of the isolates within each PFGE cluster shared identical or highly similar VNTR profiles, suggesting close epidemiological association. Irrespective of differences in risk factors and infection control policies and practices, the extent of clonality among CRAB isolates was very similar in both ICU settings. Copyright © 2011 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.
-
Bahador, Abbas; Raoofian, Reza; Pourakbari, Babak; Taheri, Mohammad; Hashemizadeh, Zahra; Hashemi, Farhad B.
2015-01-01
Carbapenem-resistant Acinetobacter baumannii (CR-AB) causes serious nosocomial infections, especially in ICU wards of hospitals, worldwide. Expression of blaOXA genes is the chief mechanism of conferring carbapenem resistance among CR-AB. Although some blaOXA genes have been studied among CR-AB isolates from Iran, their blaOXA-23-like genes have not been investigated. We used a multiplex-PCR to detect Ambler class A, B, and D carbapenemases of 85 isolates, and determined that 34 harbored blaOXA-23-like genes. Amplified fragment length polymorphism (AFLP) genotyping, followed by DNA sequencing of blaOXA-23-like amplicons of CR-AB from each AFLP group was used to characterize their blaOXA-23-like genes. We also assessed the antimicrobial susceptibility pattern of CR-AB isolates, and tested whether they harbored insertion sequences ISAba1 and ISAba4. Sequence comparison with reference strain A. baumannii (NCTC12156) revealed five types of mutations in blaOXA-23-like genes; including one novel variant and four mutants that were already reported from China and the USA. All of the blaOXA-23-like genes mutations were associated with increased minimum inhibitory concentrations (MICs) against imipenem. ISAba1 and ISAba4 sequences were detected upstream of blaOXA-23 genes in 19 and 7% of isolates, respectively. The isolation of CR-AB with new blaOXA-23 mutations including some that have been reported from the USA and China highlights CR-AB pervasive distribution, which underscores the importance of concerted national and global efforts to control the spread of CR-AB isolates worldwide. PMID:26617588