Activity of nadifloxacin (OPC-7251) and seven other antimicrobial agents against aerobic and anaerobic Gram-positive bacteria isolated from bacterial skin infections.

PubMed

Nenoff, P; Haustein, U-F; Hittel, N

2004-10-01

The in vitro activity of nadifloxacin (OPC-7251), a novel topical fluoroquinolone, was assessed and compared with those of ofloxacin, oxacillin, flucloxacillin, cefotiam, erythromycin, clindamycin, and gentamicin against 144 Gram-positive bacteria: 28 Staphylococcus aureus, 10 Streptococcus spp., 68 coagulase-negative staphylococci (CNS), 36 Propionibacterium acnes, and 2 Propionibacterium granulosum strains. All strains originated from bacterial-infected skin disease and were isolated from patients with impetigo, secondary infected wounds, folliculitis and sycosis vulgaris, and impetiginized dermatitis. In vitro susceptibility of all clinical isolates was tested by agar dilution procedure and minimum inhibitory concentrations (MICs) were determined. Nadifloxacin was active against all aerobic and anaerobic isolates. MIC(90) (MIC at which 90% of the isolates are inhibited) was 0.1 microg/ml for S. aureus, 0.78 microg/ml for both Streptococcus spp. and CNS, and 0.39 microg/ml for Propionibacterium spp. On the other hand, resistant strains with MICs exceeding 12.5 mug/ml were found in tests with the other antibiotics. For both CNS and Propionibacterium acnes, MIC(90) values > or =100 microg/ml were demonstrated for erythromycin. Ofloxacin, cefotiam, erythromycin, clindamycin and gentamicin exhibited MIC(90) values < or =1 microg/ml for some bacterial species tested. Both oxacillin and flucloxacillin were active against all investigated bacterial species with MIC(90) values < or =1 microg/ml. In summary, nadifloxacin, a topical fluoroquinolone, was found to be highly active against aerobic and anaerobic bacteria isolated from patients with infected skin disease, and seems to be a new alternative for topical antibiotic treatment in bacterial skin infections.

Monochloramine inactivation of bacterial select agents.

PubMed

Rose, Laura J; Rice, Eugene W; Hodges, Lisa; Peterson, Alicia; Arduino, Matthew J

2007-05-01

Seven species of bacterial select agents were tested for susceptibility to monochloramine. Under test conditions, the monochloramine routinely maintained in potable water would reduce six of the species by 2 orders of magnitude within 4.2 h. Bacillus anthracis spores would require up to 3.5 days for the same inactivation with monochloramine.

Phenotypic Characterization and Antibiogram of CSF Isolates in Acute Bacterial Meningitis.

PubMed

Modi, Syamal; Anand, Amit Kumar

2013-12-01

Acute bacterial meningitis (ABM) is a medical emergency, which warrants an early diagnosis and an aggressive therapy. Despite the availability of potent newer antibiotics, the mortality rate caused by acute bacterial meningitis remains significantly high in India and in other developing countries, which ranges from 16 - 32%. There is a need of a periodic review of bacterial meningitis worldwide, since the pathogens which are responsible for the infection may vary with time, geography and the age of the patient. Our aim was to study the bacterial profiles and antimicrobial susceptibility patterns of the CSF isolates which were obtained from patients of acute bacterial meningitis in our area. Two hundred and fifty two clinically diagnosed cases of acute bacterial meningitis, who were admitted to the wards of a tertiary medical centre in Patna, during the period from August 2011 to December 2012, were included in this study. Two hundred and fifty two CSF samples from as many patients of ABM were processed for cell counts, biochemical analysis, gram staining, culture, antigen detection by latex agglutination test (LAT) and antibiotic susceptibility tests, as per the standard techniques. In this study, 62.3% patients were males and 37.7% were females The most common age group of presentation was 12-60 years (80.2%). Gram stained smears were positive in 162 (64.3%) samples, while culture yielded positive growth in 200 (79.4%) patients. Streptococcus pneumoniae was the most common pathogen which was isolated in 120 (60%) culture positive cases. Cell counts showed the predominance of neutrophils in all cases with ABM. High protein and low sugar levels correlated well with the features of ABM. All gram positive isolates were sensitive to vancomycin. All the gram negative isolates were sensitive to imipenem. Twenty two (8.7%) patients expired during the course of study. Deaths were caused by N.meningitidis in 9 (40.9%) cases, by S.pneumoniae in 3 (13.6%) cases and by H

Evolvable social agents for bacterial systems modeling.

PubMed

Paton, Ray; Gregory, Richard; Vlachos, Costas; Saunders, Jon; Wu, Henry

2004-09-01

We present two approaches to the individual-based modeling (IbM) of bacterial ecologies and evolution using computational tools. The IbM approach is introduced, and its important complementary role to biosystems modeling is discussed. A fine-grained model of bacterial evolution is then presented that is based on networks of interactivity between computational objects representing genes and proteins. This is followed by a coarser grained agent-based model, which is designed to explore the evolvability of adaptive behavioral strategies in artificial bacteria represented by learning classifier systems. The structure and implementation of the two proposed individual-based bacterial models are discussed, and some results from simulation experiments are presented, illustrating their adaptive properties.

In vitro bacterial isolate susceptibility to empirically selected antimicrobials in 111 dogs with bacterial pneumonia.

PubMed

Proulx, Alexandre; Hume, Daniel Z; Drobatz, Kenneth J; Reineke, Erica L

2014-01-01

To determine the proportion of airway bacterial isolates resistant to both empirically selected and recently administered antimicrobials, and to assess the impact of inappropriate initial empiric antimicrobials selection on length of hospital stay and survival to discharge in dogs with bacterial pneumonia. Retrospective study. University veterinary teaching hospital. One hundred and eleven dogs with a clinical diagnosis of bacterial pneumonia that had aerobic bacterial culture and susceptibility testing performed from a tracheal wash sample. None. Overall, 26% (29/111) of the dogs had at least 1 bacterial isolate that was resistant to empirically selected antimicrobials. In dogs with a history of antimicrobial administration within the preceding 4 weeks, a high incidence (57.4%, 31/54) of in vitro bacterial resistance to those antimicrobials was found: 64.7% (11/17) in the community-acquired pneumonia group, 55.2% (16/29) in the aspiration pneumonia group, and 50.0% (4/8) in the other causes of bacterial pneumonia group. No statistically significant association was found between bacterial isolate resistance to empirically selected antimicrobials and length of hospital stay or mortality. The high proportion of in vitro airway bacterial resistance to empiric antimicrobials would suggest that airway sampling for bacterial culture and susceptibility testing may be helpful in guiding antimicrobial therapy and recently administered antimicrobials should be avoided when empirically selecting antimicrobials. Although no relationship was found between inappropriate initial empiric antimicrobial selection and length of hospital stay or mortality, future prospective studies using standardized airway-sampling techniques, treatment modalities, and stratification of disease severity based on objective values, such as arterial blood gas analysis in all dogs with pneumonia, would be needed to determine if a clinical effect of in vitro bacterial resistance to empirically

Microbiological etiology and susceptibility of bacterial conjunctivitis isolates from clinical trials with ophthalmic, twice-daily besifloxacin.

PubMed

Haas, Wolfgang; Gearinger, Lynne S; Hesje, Christine K; Sanfilippo, Christine M; Morris, Timothy W

2012-05-01

Bacterial conjunctivitis is a contagious infection of the surface of the eye usually treated empirically with topical antibiotics. Since the etiologic agent is rarely identified, it is important to monitor which bacteria cause conjunctivitis and determine their antibacterial resistance profiles. A total of 496 bacterial samples were isolated during a randomized, double-masked, vehicle-controlled, parallel-group study conducted in the United States with besifloxacin ophthalmic suspension 0.6% dosed twice daily. Species were determined by standard biochemical and/or molecular identification methods. Minimum inhibitory concentrations were determined according to Clinical and Laboratory Standards Institute standards. The most prevalent species was Haemophilus influenzae, followed by Staphylococcus epidermidis, Staphylococcus aureus, the Streptococcus mitis group, and Streptococcus pneumoniae. One species identified in this study, which was not previously noted as a common cause of bacterial conjunctivitis, was Dolosigranulum pigrum. Ampicillin resistance was common among H. influenzae isolates, while macrolide resistance was high among S. pneumoniae, S. epidermidis, and S. aureus. The latter two species also included a number of isolates resistant to methicillin and ciprofloxacin. Antibiotic resistance among isolates remains a concern and the appearance of an emerging ocular pathogen, D. pigrum, suggests the need for continued observation. The topical ophthalmic fluoroquinolones continue to provide a good balance of low to moderate (i.e., manageable) levels of resistance plus broad-spectrum coverage for empiric treatment of ocular infections.

The Three Bacterial Lines of Defense against Antimicrobial Agents.

PubMed

Zhou, Gang; Shi, Qing-Shan; Huang, Xiao-Mo; Xie, Xiao-Bao

2015-09-09

Antimicrobial agents target a range of extra- and/or intracellular loci from cytoplasmic wall to membrane, intracellular enzymes and genetic materials. Meanwhile, many resistance mechanisms employed by bacteria to counter antimicrobial agents have been found and reported in the past decades. Based on their spatially distinct sites of action and distribution of location, antimicrobial resistance mechanisms of bacteria were categorized into three groups, coined the three lines of bacterial defense in this review. The first line of defense is biofilms, which can be formed by most bacteria to overcome the action of antimicrobial agents. In addition, some other bacteria employ the second line of defense, the cell wall, cell membrane, and encased efflux pumps. When antimicrobial agents permeate the first two lines of defense and finally reach the cytoplasm, many bacteria will make use of the third line of defense, including alterations of intracellular materials and gene regulation to protect themselves from harm by bactericides. The presented three lines of defense theory will help us to understand the bacterial resistance mechanisms against antimicrobial agents and design efficient strategies to overcome these resistances.

Orbital abscess bacterial isolates and in vitro antimicrobial susceptibility patterns in dogs and cats.

PubMed

Wang, Annie L; Ledbetter, Eric C; Kern, Thomas J

2009-01-01

To determine bacterial populations, in vitro antimicrobial susceptibility patterns, and sources of microorganisms for dogs and cats with orbital abscess. In total, 34 dogs and 7 cats with orbital abscess participated in the study. Medical records of dogs and cats with a clinical diagnosis of orbital abscess, confirmed by cytologic or histopathologic evaluation of orbital specimens, were reviewed from the years 1990 to 2007. Animal signalment, presumptive source of microorganisms and mechanism of orbital introduction, bacterial isolates, and aerobic bacterial in vitro antimicrobial susceptibility test results were recorded. Percentages of susceptible aerobic bacterial isolates were compared among antimicrobials. Twenty dogs and five cats had positive culture results. The most frequent bacterial genera isolated from dogs were Staphylococcus, Escherichia, Bacteroides, Clostridium and Pasteurella. The most frequent bacterial genera isolated from cats were Pasteurella and Bacteroides. Aerobic bacterial isolates from dogs had the highest percentage of susceptibility to amikacin, ceftiofur, gentamicin, imipenem, ticarcillin and trimethoprim-sulfamethoxazole. Aerobic bacterial isolates from dogs had the lowest percentage of susceptibility to ampicillin, clindamycin, erythromycin and penicillin. Antimicrobial resistance was uncommon among feline aerobic bacterial isolates. The most commonly identified routes of orbital bacteria introduction were extension from adjacent anatomical structures, penetrating exogenous trauma, and foreign bodies. Mixed aerobic and anaerobic bacterial infections of the orbit occur commonly in dogs and cats. On the basis of aerobic and anaerobic bacterial isolates and in vitro susceptibility testing of aerobic bacterial isolates, cephalosporins, extended-spectrum penicillins, potentiated-penicillins and carbapenems are recommended for initial antimicrobial therapy of orbital abscess in dogs and cats.

Isolation of biologically active nanomaterial (inclusion bodies) from bacterial cells.

PubMed

Peternel, Spela; Komel, Radovan

2010-09-10

In recent years bacterial inclusion bodies (IBs) were recognised as highly pure deposits of active proteins inside bacterial cells. Such active nanoparticles are very interesting for further downstream protein isolation, as well as for many other applications in nanomedicine, cosmetic, chemical and pharmaceutical industry.To prepare large quantities of a high quality product, the whole bioprocess has to be optimised. This includes not only the cultivation of the bacterial culture, but also the isolation step itself, which can be of critical importance for the production process.To determine the most appropriate method for the isolation of biologically active nanoparticles, three methods for bacterial cell disruption were analyzed. In this study, enzymatic lysis and two mechanical methods, high-pressure homogenization and sonication, were compared.During enzymatic lysis the enzyme lysozyme was found to attach to the surface of IBs, and it could not be removed by simple washing. As this represents an additional impurity in the engineered nanoparticles, we concluded that enzymatic lysis is not the most suitable method for IBs isolation.During sonication proteins are released (lost) from the surface of IBs and thus the surface of IBs appears more porous when compared to the other two methods. We also found that the acoustic output power needed to isolate the IBs from bacterial cells actually damages proteins structures, thereby causing a reduction in biological activity.High-pressure homogenization also caused some damage to IBs, however the protein loss from the IBs was negligible. Furthermore, homogenization had no side-effects on protein biological activity. The study shows that among the three methods tested, homogenization is the most appropriate method for the isolation of active nanoparticles from bacterial cells.

Ocular surface infections in northeastern state of malaysia: a 10-year review of bacterial isolates and antimicrobial susceptibility.

PubMed

Rahman, Zaidah A; Harun, Azian; Hasan, Habsah; Mohamed, Zeehaida; Noor, Siti S Md; Deris, Zakuan Z; Ismail, Nabilah; Hassan, Asma S; Ahmad, Fadzhilah; Yaakub, Azhany

2013-09-01

Ocular surface infections that include infections of conjunctiva, adnexa, and cornea have the potential risk of causing blindness within a given population. Empirical antibiotic therapy is usually initiated based on epidemiological data of common causative agents. Thus, the aims of this study were to determine the bacterial agents and their susceptibility patterns of isolates from ocular surface specimens in our hospital. This is a retrospective analysis and records of bacterial isolates from ocular surface specimens in Hospital Universiti Sains Malaysia from January 2001 to December 2010 were examined. Specimens were processed according to standard laboratory procedures. Antimicrobial susceptibility testing was conducted based on Clinical and Laboratory Standards Institute recommendations. Only single, nonrepetitive isolates were included in the analysis. A total of 1,267 isolates were obtained during the study period, which comprised Staphylococcus aureus (n = 299, 23.6%), Pseudomonas aeruginosa (n = 194, 15.3%), Streptococcus pneumoniae (n = 108, 8.5%), Haemophilus influenzae (n = 100, 7.9%), Haemophilus parainfluenzae (n = 84, 6.6%), and Enterobacter spp. (n = 81, 6.4%). Fungi contributed to 4.4% of the total isolates. The antimicrobial susceptibility testing demonstrated that gram-positive bacteria were generally resistant to gentamicin (19%-57%), whereas gram-negative bacteria were resistant to chloramphenicol (27%-58%). Based on the above results, knowledge of the initial Gram stain findings is imperative before the commencement of empirical antibiotic therapy. Therefore, a simple Gram staining for all eye specimens is highly recommended.

Clonality of Bacterial Pathogens Causing Hospital-Acquired Pneumonia.

PubMed

Pudová, V; Htoutou Sedláková, M; Kolář, M

2016-09-01

Hospital-acquired pneumonia (HAP) is one of the most serious complications in patients staying in intensive care units. This multicenter study of Czech patients with HAP aimed at assessing the clonality of bacterial pathogens causing the condition. Bacterial isolates were compared using pulsed-field gel electrophoresis. Included in this study were 330 patients hospitalized between May 1, 2013 and December 31, 2014 at departments of anesthesiology and intensive care medicine of four big hospitals in the Czech Republic. A total of 531 bacterial isolates were obtained, of which 267 were classified as etiological agents causing HAP. Similarity or identity was assessed in 231 bacterial isolates most frequently obtained from HAP patients. Over the study period, no significant clonal spread was noted. Most isolates were unique strains, and the included HAP cases may therefore be characterized as mostly endogenous. Yet there were differences in species and potential identical isolates between the participating centers. In three hospitals, Gram-negative bacteria (Enterobacteriaceae and Pseudomonas aeruginosa) prevailed as etiological agents, and Staphylococcus aureus was most prevalent in the fourth center.

Isolation of biologically active nanomaterial (inclusion bodies) from bacterial cells

PubMed Central

2010-01-01

Background In recent years bacterial inclusion bodies (IBs) were recognised as highly pure deposits of active proteins inside bacterial cells. Such active nanoparticles are very interesting for further downstream protein isolation, as well as for many other applications in nanomedicine, cosmetic, chemical and pharmaceutical industry. To prepare large quantities of a high quality product, the whole bioprocess has to be optimised. This includes not only the cultivation of the bacterial culture, but also the isolation step itself, which can be of critical importance for the production process. To determine the most appropriate method for the isolation of biologically active nanoparticles, three methods for bacterial cell disruption were analyzed. Results In this study, enzymatic lysis and two mechanical methods, high-pressure homogenization and sonication, were compared. During enzymatic lysis the enzyme lysozyme was found to attach to the surface of IBs, and it could not be removed by simple washing. As this represents an additional impurity in the engineered nanoparticles, we concluded that enzymatic lysis is not the most suitable method for IBs isolation. During sonication proteins are released (lost) from the surface of IBs and thus the surface of IBs appears more porous when compared to the other two methods. We also found that the acoustic output power needed to isolate the IBs from bacterial cells actually damages proteins structures, thereby causing a reduction in biological activity. High-pressure homogenization also caused some damage to IBs, however the protein loss from the IBs was negligible. Furthermore, homogenization had no side-effects on protein biological activity. Conclusions The study shows that among the three methods tested, homogenization is the most appropriate method for the isolation of active nanoparticles from bacterial cells. PMID:20831775

Isolation and identification of biocellulose-producing bacterial strains from Malaysian acidic fruits.

PubMed

Voon, W W Y; Rukayadi, Y; Meor Hussin, A S

2016-05-01

Biocellulose (BC) is pure extracellular cellulose produced by several species of micro-organisms that has numerous applications in the food, biomedical and paper industries. However, the existing biocellulose-producing bacterial strain with high yield was limited. The aim of this study was to isolate and identify the potential biocellulose-producing bacterial isolates from Malaysian acidic fruits. One hundred and ninety-three bacterial isolates were obtained from 19 local acidic fruits collected in Malaysia and screened for their ability to produce BC. A total of 15 potential bacterial isolates were then cultured in standard Hestrin-Schramm (HS) medium statically at 30°C for 2 weeks to determine the BC production. The most potent bacterial isolates were identified using 16S rRNA gene sequence analysis, morphological and biochemical characteristics. Three new and potent biocellulose-producing bacterial strains were isolated from soursop fruit and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. Stenotrophomonas maltophilia WAUPM42 was the most potent biocellulose-producing bacterial strain that produced the highest amount of BC 0·58 g l(-1) in standard HS medium. Whereas, the isolates P. vagans WAUPM45 and B. fluminensis WAUPM53 showed 0·50 and 0·52 g l(-1) of BC production, respectively. Biocellulose (BC) is pure extracellular cellulose that is formed by many micro-organisms in the presence of carbon source and acidic condition. It can replace plant-based cellulose in multifarious applications due to its unique characteristics. In this study, three potential biocellulose-producing bacterial strains were obtained from Malaysian acidic fruits and identified as Stenotrophomonas maltophilia WAUPM42, Pantoea vagans WAUPM45 and Beijerinckia fluminensis WAUPM53. This study reports for the first time the new biocellulose-producing bacterial strains isolated from Malaysian acidic fruits. © 2016 The

The Three Bacterial Lines of Defense against Antimicrobial Agents

PubMed Central

Zhou, Gang; Shi, Qing-Shan; Huang, Xiao-Mo; Xie, Xiao-Bao

2015-01-01

Antimicrobial agents target a range of extra- and/or intracellular loci from cytoplasmic wall to membrane, intracellular enzymes and genetic materials. Meanwhile, many resistance mechanisms employed by bacteria to counter antimicrobial agents have been found and reported in the past decades. Based on their spatially distinct sites of action and distribution of location, antimicrobial resistance mechanisms of bacteria were categorized into three groups, coined the three lines of bacterial defense in this review. The first line of defense is biofilms, which can be formed by most bacteria to overcome the action of antimicrobial agents. In addition, some other bacteria employ the second line of defense, the cell wall, cell membrane, and encased efflux pumps. When antimicrobial agents permeate the first two lines of defense and finally reach the cytoplasm, many bacteria will make use of the third line of defense, including alterations of intracellular materials and gene regulation to protect themselves from harm by bactericides. The presented three lines of defense theory will help us to understand the bacterial resistance mechanisms against antimicrobial agents and design efficient strategies to overcome these resistances. PMID:26370986

Isolation, characterization, and identification of biological control agent for potato soft rot in Bangladesh.

PubMed

Rahman, M M; Ali, M E; Khan, A A; Akanda, A M; Uddin, Md Kamal; Hashim, U; Abd Hamid, S B

2012-01-01

A total of 91 isolates of probable antagonistic bacteria of potato soft rot bacterium Erwinia carotovora subsp. carotovora (Ecc) were extracted from rhizospheres and endophytes of various crop plants, different soil varieties, and atmospheres in the potato farming areas of Bangladesh. Antibacterial activity of the isolated probable antagonistic bacteria was tested in vitro against the previously identified most common and most virulent soft rot causing bacterial strain Ecc P-138. Only two isolates E-45 and E-65 significantly inhibited the in vitro growth of Ecc P-138. Physiological, biochemical, and carbon source utilization tests identified isolate E-65 as a member of the genus Bacillus and the isolate E-45 as Lactobacillus sp. The stronger antagonistic activity against Ecc P-138 was found in E-65 in vitro screening and storage potatoes. E-65 reduced the soft rot infection to 22-week storage potatoes of different varieties by 32.5-62.5% in model experiment, demonstrating its strong potential to be used as an effective biological control agent for the major pectolytic bacteria Ecc. The highest (62.5%) antagonistic effect of E-65 was observed in the Granola and the lowest (32.7%) of that was found in the Cardinal varieties of the Bangladeshi potatoes. The findings suggest that isolate E-65 could be exploited as a biocontrol agent for potato tubers.

Isolation, Characterization, and Identification of Biological Control Agent for Potato Soft Rot in Bangladesh

PubMed Central

Rahman, M. M.; Ali, M. E.; Khan, A. A.; Akanda, A. M.; Uddin, Md. Kamal; Hashim, U.; Abd Hamid, S. B.

2012-01-01

A total of 91 isolates of probable antagonistic bacteria of potato soft rot bacterium Erwinia carotovora subsp. carotovora (Ecc) were extracted from rhizospheres and endophytes of various crop plants, different soil varieties, and atmospheres in the potato farming areas of Bangladesh. Antibacterial activity of the isolated probable antagonistic bacteria was tested in vitro against the previously identified most common and most virulent soft rot causing bacterial strain Ecc P-138. Only two isolates E-45 and E-65 significantly inhibited the in vitro growth of Ecc P-138. Physiological, biochemical, and carbon source utilization tests identified isolate E-65 as a member of the genus Bacillus and the isolate E-45 as Lactobacillus sp. The stronger antagonistic activity against Ecc P-138 was found in E-65 in vitro screening and storage potatoes. E-65 reduced the soft rot infection to 22-week storage potatoes of different varieties by 32.5–62.5% in model experiment, demonstrating its strong potential to be used as an effective biological control agent for the major pectolytic bacteria Ecc. The highest (62.5%) antagonistic effect of E-65 was observed in the Granola and the lowest (32.7%) of that was found in the Cardinal varieties of the Bangladeshi potatoes. The findings suggest that isolate E-65 could be exploited as a biocontrol agent for potato tubers. PMID:22645446

Isolation of Ralstonia solanacearum-infecting bacteriophages from tomato fields in Chiang Mai, Thailand, and their experimental use as biocontrol agents.

PubMed

Bhunchoth, A; Phironrit, N; Leksomboon, C; Chatchawankanphanich, O; Kotera, S; Narulita, E; Kawasaki, T; Fujie, M; Yamada, T

2015-04-01

To isolate and characterize novel bacteriophages infecting the phytopathogen, Ralstonia solanacearum, and to evaluate them as resources with potential uses in the biocontrol of bacterial wilt. Fourteen phages infecting R. solanacearum were isolated from soil samples collected in Chiang Mai, Thailand. The phages showed different host ranges when tested against 59 R. solanacearum strains isolated from Thailand and Japan. These phages were characterized as nine podoviruses and five myoviruses based on their morphology. Podovirus J2 in combination with another podovirus (φRSB2) lysed host cells very efficiently in contaminated soil. J2 treatment prevented wilting of tomato plants infected with a highly virulent R. solanacearum strain. Treatment with J2 effectively reduced the amount of the bacterial wilt pathogen in contaminated soil and prevented bacterial wilt of tomato in pot experiments. Myovirus J6 possessed jumbo phage features, giving a unique opportunity to study its utilization as a biocontrol agent. As exemplified by J2, the phages isolated in this study represent valuable resources with potential uses in biocontrol of bacterial wilt. A rare jumbo phage J6 served as a valuable subject to understand and utilize this new group of phages. © 2015 The Society for Applied Microbiology.

Chitosanase purified from bacterial isolate Bacillus licheniformis of ruined vegetables displays broad spectrum biofilm inhibition.

PubMed

Muslim, Sahira Nsayef; Al-Kadmy, Israa M S; Hussein, Nadheema Hammood; Mohammed Ali, Alaa Naseer; Taha, Buthainah Mohammed; Aziz, Sarah Naji; Kheraif, Abdulaziz Abdullah Al; Divakar, Darshan Devang; Ramakrishnaiah, Ravikumar

2016-11-01

A number of bacterial species produces chitosanases which has variety of applications because of its high biodegradability, non-toxicity and antimicrobial assets. In the present study chitosanase is purified from new bacterial species Bacillus licheniformis from spoiled vegetable. This novel strain of Bacillus licheniformis isolated from spoilt cucumber and pepper samples has the ability to produce the chitosanase enzyme when grown on chitosan substrate. Study also examined its antibiofilm properties against diverse bacterial species with biofilm forming ability. The purified chitosanase inhibited the biofilm formation ability for all Gram-negative and Gram-positive biofilm-forming bacteria [biofilm producers] tested in this study in congo red agar and microtiter plate's methods. Highly antibiofilm activity of chitosanase was recorded against Pseudomonas aeruginosa followed by Klebsiella pneumoniae with reduction of biofilm formation upto 22 and 29%, respectively compared with [100] % of control. Biofilm formation has multiple role including ability to enhance resistance and self-protection from external stress. This chitosanase has promising benefit as antibiofilm agent against biofilm forming pathogenic bacteria and has promising application as alternative antibiofilm agents to combat the growing number of multidrug resistant pathogen-associated infections, especially in situation where biofilms are involved. Copyright © 2016 Elsevier Ltd. All rights reserved.

Bacterial isolates from equine infections in western Canada (1998–2003)

PubMed Central

Clark, Chris; Greenwood, Sarah; Boison, Joe O.; Chirino-Trejo, Manuel; Dowling, Patricia M.

2008-01-01

All bacterial samples of equine origin submitted to the diagnostic laboratory at the Western College of Veterinary Medicine from January 1998 to December 2003 from either “in-clinic” or Field Service cases were accessed (1323 submissions). The most common bacterial isolates from specific presenting signs were identified, along with their in vitro antimicrobial susceptibility patterns. The most common site from which significant bacterial isolates were recovered was the respiratory tract, followed by wounds. Streptococcus zooepidemicus was the most common isolate from most infections, followed by Escherichia coli. Antimicrobial resistance was not common in the isolates and acquired antimicrobial resistance to multiple drugs was rare. The results are compared with previous published studies from other institutions and used to suggest appropriate antimicrobial treatments for equine infections in western Canada. PMID:18309745

Evaluation of a multiplex real-time PCR for detection of four bacterial agents commonly associated with bovine respiratory disease in bronchoalveolar lavage fluid.

PubMed

Wisselink, Henk J; Cornelissen, Jan B W J; van der Wal, Fimme J; Kooi, Engbert A; Koene, Miriam G; Bossers, Alex; Smid, Bregtje; de Bree, Freddy M; Antonis, Adriaan F G

2017-07-13

Pasteurella multocida, Mannheimia haemolytica, Histophilus somni and Trueperella pyogenes are four bacterial agents commonly associated with bovine respiratory disease (BRD). In this study a bacterial multiplex real-time PCR (the RespoCheck PCR) was evaluated for the detection in bronchoalveolar lavage fluid (BALF) of these four bacterial agents. The analytical sensitivity of the multiplex real-time PCR assay determined on purified DNA and on bacterial cells of the four target pathogens was one to ten fg DNA/assay and 4 × 10 -1 to 2 × 10 0  CFU/assay. The analytical specificity of the test was, as evaluated on a collection of 118 bacterial isolates, 98.3% for M. haemolytica and 100% for the other three target bacteria. A set of 160 BALF samples of calves originating from ten different herds with health problems related to BRD was examined with bacteriological methods and with the RespoCheck PCR. Using bacteriological examination as the gold standard, the diagnostic sensitivities and specificities of the four bacterial agents were respectively between 0.72 and 1.00 and between 0.70 and 0.99. Kappa values for agreement between results of bacteriological examination and PCRs were low for H. somni (0.17), moderate for P. multocida (0.52) and M. haemolytica (0.57), and good for T. pyogenes (0.79). The low and moderate kappa values seemed to be related to limitations of the bacteriological examination, this was especially the case for H. somni. It was concluded that the RespoCheck PCR assay is a valuable diagnostic tool for the simultaneous detection of the four bacterial agents in BALF of calves.

Patterns of isolation of common gram positive bacterial pathogens and their susceptibilities to antimicrobial agents in Jimma Hospital.

PubMed

Gebreselassie, Solomon

2002-04-01

Gram positive bacteria are frequently emerging as antibiotic resistant pathogens, causing serious infections than ever before in the ill and debilitated patients. The pattern of isolation and the antimicrobial susceptibilities of common Gram positive cocci including Staphylococcus aureus, coagulase negative staphylococcus (CoNS), Streptococcus pyogenes, Enterococcus species and Streptococcus pneumoniae was investigated between January 1997 and June 2000 in Jimma Hospital. Of the 500 specimens collected from children and adults, 116 (23.2%) consisted of one or more of the above organisms. The following strains: Staphylococcus aureus, 47 (40.5%), CoNS, 36 (31.0%), Streptococcus pneumoniae, 26 (22.4%) Streptococcus pyogenes, 5 (4.3%) and Streptococcus faecalis, 2(1.7%) were isolated from different specimens including pus, sputum, urine, stool, blood and oro/nasopharyngeal swabs of patients. The in vitro activities of 14 different antibiotics including penicillin G, ampicillin, cloxacillin, cephalothin, gentamicin, kanamycin, tetracycline, chloramphenicol, erythromycin, trimethoprim-sulfamethoxazole, streptomycin, methicillin, vancomycin and clindamycin was determined against the clinical bacterial isolates. The antimicrobial activities were evaluated by agar diffusion technique using Mueller-Hinton agar according to NCCLS recommendations. The majority of the pathogens, 59(50.9%) were recovered from upper respiratory tract infections and 17 (14.6%) from the lower respiratory tract. The resistance patterns of S. aureus, CoNS, S. pneumoniae and enterococci to penicillin was 91.5%, 94.4%, 7.7% and 100% respectively. Penicillin, ampicillin and cloxacillin showed low effects (< 60%) on both S. aureus and CoNS. Multi-drug resistance was observed in all the gram-positive isolates, especially higher in staphylococcus species. All isolates of S. aureus (100%) were susceptible to vancomycin, clindamycin and gentamicin. In order to reduce morbidity and mortality due to antibiotic

Imipenem/cilastatin encapsulated polymeric nanoparticles for destroying carbapenem-resistant bacterial isolates.

PubMed

Shaaban, Mona I; Shaker, Mohamed A; Mady, Fatma M

2017-04-11

Carbapenem-resistance is an extremely growing medical threat in antibacterial therapy as the incurable resistant strains easily develop a multi-resistance action to other potent antimicrobial agents. Nonetheless, the protective delivery of current antibiotics using nano-carriers opens a tremendous approach in the antimicrobial therapy, allowing the nano-formulated antibiotics to beat these health threat pathogens. Herein, we encapsulated imipenem into biodegradable polymeric nanoparticles to destroy the imipenem-resistant bacteria and overcome the microbial adhesion and dissemination. Imipenem loaded poly Ɛ-caprolactone (PCL) and polylactide-co-glycolide (PLGA) nanocapsules were formulated using double emulsion evaporation method. The obtained nanocapsules were characterized for mean particle diameter, morphology, loading efficiency, and in vitro release. The in vitro antimicrobial and anti adhesion activities were evaluated against selected imipenem-resistant Klebsiella pneumoniae and Pseudomonas aeruginosa clinical isolates. The obtained results reveal that imipenem loaded PCL nano-formulation enhances the microbial susceptibility and antimicrobial activity of imipenem. The imipenem loaded PCL nanoparticles caused faster microbial killing within 2-3 h compared to the imipenem loaded PLGA and free drug. Successfully, PCL nanocapsules were able to protect imipenem from enzymatic degradation by resistant isolates and prevent the emergence of the resistant colonies, as it lowered the mutation prevention concentration of free imipenem by twofolds. Moreover, the imipenem loaded PCL eliminated bacterial attachment and the biofilm assembly of P. aeruginosa and K. pneumoniae planktonic bacteria by 74 and 78.4%, respectively. These promising results indicate that polymeric nanoparticles recover the efficacy of imipenem and can be considered as a new paradigm shift against multidrug-resistant isolates in treating severe bacterial infections.

New Paenibacillus larvae bacterial isolates from honey bee colonies infected with American foulbrood disease in Egypt.

PubMed

Masry, Saad Hamdy Daif; Kabeil, Sanaa Soliman; Hafez, Elsayed Elsayed

2014-03-04

The American foulbrood disease is widely distributed all over the world and causes a serious problem for the honeybee industry. Different infected larvae were collected from different apiaries, ground in phosphate saline buffer (PSB) and bacterial isolation was carried out on nutrient agar medium. Different colonies were observed and were characterized biologically. Two bacterial isolates (SH11 and SH33) were subjected to molecular identification using 16S rRNA gene and the sequence analysis revealed that the two isolates are Paenibacillus larvae with identity not exceeding 83%. The DNA sequence alignment between the other P. larvae bacterial strains and the two identified bacterial isolates showed that all the examined bacterial strains have the same ancestor, i.e. they have the same origin. The SH33 isolate was closely related to the P. larvae isolated from Germany, whereas the isolate SH11 was close to the P. larvae isolated from India. The phylogenetic tree constructed for 20 different Bacillus sp. and the two isolates SH11 and SH33 demonstrated that the two isolates are Bacillus sp. and they are new isolates. The bacterial isolates will be subjected to more tests for more confirmations.

Incidence of bacterial respiratory pathogens and their susceptibility to common antibacterial agents.

PubMed Central

Qadri, S. M.; Lee, G. C.; Ueno, Y.; Burdette, J. M.

1993-01-01

Although most respiratory tract infections are caused by viruses, bacterial pathogens are responsible for higher morbidity and mortality. Because virtually nothing is known about the etiology of bacterial respiratory pathogens in Saudi Arabia, this study examined the incidence of these organisms in 5426 patients over a 1-year period. Of the bacterial pathogens isolated from 904 patients, the most common organism was Hemophilus influenzae (31%), followed by pneumococci (22%), Pseudomonas aeruginosa (16%), and others (31%). Because the first two organisms accounted for more than 50% of isolates, their susceptibility to commonly used antibiotics was also reviewed. The results are presented here. PMID:8496993

Oviposition responses of Aedes mosquitoes to bacterial isolates from attractive bamboo infusions.

PubMed

Ponnusamy, Loganathan; Schal, Coby; Wesson, Dawn M; Arellano, Consuelo; Apperson, Charles S

2015-09-23

The mosquitoes Aedes aegypti and Aedes albopictus are vectors of pathogenic viruses that cause major human illnesses including dengue, yellow fever and chikungunya. Both mosquito species are expanding their geographic distributions and now occur worldwide in temperate and tropical climates. Collection of eggs in oviposition traps (ovitraps) is commonly used for monitoring and surveillance of container-inhabiting Aedes populations by public health agencies charged with managing mosquito-transmitted illness. Addition of an organic infusion in these traps increases the number of eggs deposited. Gravid females are guided to ovitraps by volatile chemicals produced from the breakdown of organic matter by microbes. We previously isolated and cultured 14 species of bacteria from attractive experimental infusions, made from the senescent leaves of canebrake bamboo (Arundinaria gigantea). Cultures were grown for 24 h at 28 °C with constant shaking (120 rpm) and cell densities were determined with a hemocytometer. Behavioral responses to single bacterial isolates and to a mix of isolates at different cell densities were evaluated using two-choice sticky-screen bioassay methods with gravid Ae. aegypti and Ae. albopictus. In behavioral assays of a mix of 14 bacterial isolates, significantly greater attraction responses were exhibited by Ae. aegypti and Ae. albopictus to bacterial densities of 10(7) and 10(8) cells/mL than to the control medium. When we tested single bacterial isolates, seven isolates (B1, B2, B3, B5, B12, B13 and B14) were significantly attractive to Ae. aegypti, and six isolates (B1, B5, B7, B10, B13 and B14) significantly attracted Ae. albopictus. Among all the isolates tested at three different cell densities, bacterial isolates B1, B5, B13 and B14 were highly attractive to both Aedes species. Our results show that at specific cell densities, some bacteria significantly influence the attraction of gravid Ae. aegypti and Ae. albopictus females to

In Search of Alternative Antibiotic Drugs: Quorum-Quenching Activity in Sponges and their Bacterial Isolates

PubMed Central

Saurav, Kumar; Bar-Shalom, Rinat; Haber, Markus; Burgsdorf, Ilia; Oliviero, Giorgia; Costantino, Valeria; Morgenstern, David; Steindler, Laura

2016-01-01

Owing to the extensive development of drug resistance in pathogens against the available antibiotic arsenal, antimicrobial resistance is now an emerging major threat to public healthcare. Anti-virulence drugs are a new type of therapeutic agent aiming at virulence factors rather than killing the pathogen, thus providing less selective pressure for evolution of resistance. One promising example of this therapeutic concept targets bacterial quorum sensing (QS), because QS controls many virulence factors responsible for bacterial infections. Marine sponges and their associated bacteria are considered a still untapped source for unique chemical leads with a wide range of biological activities. In the present study, we screened extracts of 14 sponge species collected from the Red and Mediterranean Sea for their quorum-quenching (QQ) potential. Half of the species showed QQ activity in at least 2 out of 3 replicates. Six out of the 14 species were selected for bacteria isolation, to test for QQ activity also in isolates, which, once cultured, represent an unlimited source of compounds. We show that ≈20% of the isolates showed QQ activity based on a Chromobacterium violaceum CV026 screen, and that the presence or absence of QQ activity in a sponge extract did not correlate with the abundance of isolates with the same activity from the same sponge species. This can be explained by the unknown source of QQ compounds in sponge-holobionts (host or symbionts), and further by the possible non-symbiotic nature of bacteria isolated from sponges. The potential symbiotic nature of the isolates showing QQ activity was tested according to the distribution and abundance of taxonomically close bacterial Operational Taxonomic Units (OTUs) in a dataset including 97 sponge species and 178 environmental samples (i.e., seawater, freshwater, and marine sediments). Most isolates were found not to be enriched in sponges and may simply have been trapped in the filtration channels of the

Screening of bacterial strains isolated from uranium mill tailings porewaters for bioremediation purposes.

PubMed

Sánchez-Castro, Iván; Amador-García, Ahinara; Moreno-Romero, Cristina; López-Fernández, Margarita; Phrommavanh, Vannapha; Nos, Jeremy; Descostes, Michael; Merroun, Mohamed L

2017-01-01

The present work characterizes at different levels a number of bacterial strains isolated from porewaters sampled in the vicinity of two French uranium tailing repositories. The 16S rRNA gene from 33 bacterial isolates, corresponding to the different morphotypes recovered, was almost fully sequenced. The resulting sequences belonged to 13 bacterial genera comprised in the phyla Firmicutes, Actinobacteria and Proteobacteria. Further characterization at physiological level and metals/metalloid tolerance provided evidences for an appropriate selection of bacterial strains potentially useful for immobilization of uranium and other common contaminants. By using High Resolution Transmission Electron Microscope (HRTEM), this potential ability to immobilize uranium as U phosphate mineral phases was confirmed for the bacterial strains Br3 and Br5 corresponding to Arthrobacter sp. and Microbacterium oxydans, respectively. Scanning Transmission Electron Microscope- High-Angle Annular Dark-Field (STEM-HAADF) analysis showed U accumulates on the surface and within bacterial cytoplasm, in addition to the extracellular space. Energy Dispersive X-ray (EDX) element-distribution maps demonstrated the presence of U and P within these accumulates. These results indicate the potential of certain bacterial strains isolated from porewaters of U mill tailings for immobilizing uranium, likely as uranium phosphates. Some of these bacterial isolates might be considered as promising candidates in the design of uranium bioremediation strategies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Biodegradation of complex hydrocarbons in spent engine oil by novel bacterial consortium isolated from deep sea sediment.

PubMed

Ganesh Kumar, A; Vijayakumar, Lakshmi; Joshi, Gajendra; Magesh Peter, D; Dharani, G; Kirubagaran, R

2014-10-01

Complex hydrocarbon and aromatic compounds degrading marine bacterial strains were isolated from deep sea sediment after enrichment on spent engine (SE) oil. Phenotypic characterization and phylogenetic analysis of 16S rRNA gene sequences showed the isolates were related to members of the Pseudoalteromonas sp., Ruegeria sp., Exiguobacterium sp. and Acinetobacter sp. Biodegradation using 1% (v/v) SE oil with individual and mixed strains showed the efficacy of SE oil utilization within a short retention time. The addition of non-ionic surfactant 0.05% (v/v) Tween 80 as emulsifying agent enhanced the solubility of hydrocarbons and renders them more accessible for biodegradation. The degradation of several compounds and the metabolites formed during the microbial oxidation process were confirmed by Fourier transform infrared spectroscopy and Gas chromatography-mass spectrometry analyses. The potential of this consortium to biodegrade SE oil with and without emulsifying agent provides possible application in bioremediation of oil contaminated marine environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

Isolation of cell-free bacterial inclusion bodies.

PubMed

Rodríguez-Carmona, Escarlata; Cano-Garrido, Olivia; Seras-Franzoso, Joaquin; Villaverde, Antonio; García-Fruitós, Elena

2010-09-17

Bacterial inclusion bodies are submicron protein clusters usually found in recombinant bacteria that have been traditionally considered as undesirable products from protein production processes. However, being fully biocompatible, they have been recently characterized as nanoparticulate inert materials useful as scaffolds for tissue engineering, with potentially wider applicability in biomedicine and material sciences. Current protocols for inclusion body isolation from Escherichia coli usually offer between 95 to 99% of protein recovery, what in practical terms, might imply extensive bacterial cell contamination, not compatible with the use of inclusion bodies in biological interfaces. Using an appropriate combination of chemical and mechanical cell disruption methods we have established a convenient procedure for the recovery of bacterial inclusion bodies with undetectable levels of viable cell contamination, below 10⁻¹ cfu/ml, keeping the particulate organization of these aggregates regarding size and protein folding features. The application of the developed protocol allows obtaining bacterial free inclusion bodies suitable for use in mammalian cell cultures and other biological interfaces.

Biocontrol of Sugarcane Smut Disease by Interference of Fungal Sexual Mating and Hyphal Growth Using a Bacterial Isolate.

PubMed

Liu, Shiyin; Lin, Nuoqiao; Chen, Yumei; Liang, Zhibin; Liao, Lisheng; Lv, Mingfa; Chen, Yufan; Tang, Yingxin; He, Fei; Chen, Shaohua; Zhou, Jianuan; Zhang, Lianhui

2017-01-01

Sugarcane smut is a fungal disease caused by Sporisorium scitamineum , which can cause severe economic losses in sugarcane industry. The infection depends on the mating of bipolar sporida to form a dikaryon and develops into hyphae to penetrate the meristematic tissue of sugarcane. In this study, we set to isolate bacterial strains capable of blocking the fungal mating and evaluate their potential in control of sugarcane smut disease. A bacterial isolate ST4 from rhizosphere displayed potent inhibitory activity against the mating of S. scitamineum bipolar sporida and was selected for further study. Phylogenetic analyses and biochemical characterization showed that the isolate was most similar to Pseudomonas guariconensis . Methanol extracts from minimum and potato dextrose agar (PDA) agar medium, on which strain ST4 has grown, showed strong inhibitory activity on the sexual mating of S. scitamineum sporida, without killing the haploid cells MAT-1 or MAT-2. Further analysis showed that only glucose, but not sucrose, maltose, and fructose, could support strain ST4 to produce antagonistic chemicals. Consistent with the above findings, greenhouse trials showed that addition of 2% glucose to the bacterial inoculum significantly increased the strain ST4 biocontrol efficiency against sugarcane smut disease by 77% than the inoculum without glucose. The results from this study depict a new strategy to screen for biocontrol agents for control and prevention of the sugarcane smut disease.

Validation of hierarchical cluster analysis for identification of bacterial species using 42 bacterial isolates

NASA Astrophysics Data System (ADS)

Ghebremedhin, Meron; Yesupriya, Shubha; Luka, Janos; Crane, Nicole J.

2015-03-01

Recent studies have demonstrated the potential advantages of the use of Raman spectroscopy in the biomedical field due to its rapidity and noninvasive nature. In this study, Raman spectroscopy is applied as a method for differentiating between bacteria isolates for Gram status and Genus species. We created models for identifying 28 bacterial isolates using spectra collected with a 785 nm laser excitation Raman spectroscopic system. In order to investigate the groupings of these samples, partial least squares discriminant analysis (PLSDA) and hierarchical cluster analysis (HCA) was implemented. In addition, cluster analyses of the isolates were performed using various data types consisting of, biochemical tests, gene sequence alignment, high resolution melt (HRM) analysis and antimicrobial susceptibility tests of minimum inhibitory concentration (MIC) and degree of antimicrobial resistance (SIR). In order to evaluate the ability of these models to correctly classify bacterial isolates using solely Raman spectroscopic data, a set of 14 validation samples were tested using the PLSDA models and consequently the HCA models. External cluster evaluation criteria of purity and Rand index were calculated at different taxonomic levels to compare the performance of clustering using Raman spectra as well as the other datasets. Results showed that Raman spectra performed comparably, and in some cases better than, the other data types with Rand index and purity values up to 0.933 and 0.947, respectively. This study clearly demonstrates that the discrimination of bacterial species using Raman spectroscopic data and hierarchical cluster analysis is possible and has the potential to be a powerful point-of-care tool in clinical settings.

New media for the semiselective isolation and enumeration of Xanthomonas campestris pv. mangiferaeindicae, the causal agent of mango bacterial black spot.

PubMed

Pruvost, O; Roumagnac, P; Gaube, C; Chiroleu, F; Gagnevin, L

2005-01-01

Mango bacterial black spot, caused by Xanthomonas campestris pv. mangiferaeindicae, is a potentially severe disease in several tropical and subtropical areas. Data describing the life cycle of the pathogen are needed for improving integrated pest management strategies. Because of the important bacterial microflora associated with mango leaves, isolation of the pathogen is often difficult using nonselective agar media. A previously developed medium, BVGA, failed to inhibit several Gram-negative saprophytic bacteria, especially those belonging to Enterobacteriaceae. Two new semiselective media were developed. The selectivity of KC and NCTM3 media was achieved using cephalexin 40 mg l(-1), kasugamycin 20 mg l(-1) and neomycin 1 mg l(-1), cephalexin 100 mg l(-1), trimethoprime 5 mg l(-1), pivmecillinam 100 mg l(-1) respectively. Plating efficiencies ranged from 76 to 104% and from 78 to 132% for KC and NCTM3 respectively. The new media allowed the growth of X. campestris pv. mangiferaeindicae whatever its country of isolation. The pathogen was repeatedly isolated with these media from asymptomatic leaves sampled in growth chamber experiments. This work provides a description of new semiselective media, which should be valuable tools to study the ecology and epidemiology of X. campestris pv. mangiferaeindicae.

Volatile organic compounds produced by a soil-isolate, Bacillus subtilis FA26 induce adverse ultra-structural changes to the cells of Clavibacter michiganensis ssp. sepedonicus, the causal agent of bacterial ring rot of potato.

PubMed

Rajer, Faheem Uddin; Wu, Huijun; Xie, Yongli; Xie, Shanshan; Raza, Waseem; Tahir, Hafiz Abdul Samad; Gao, Xuewen

2017-04-01

Rhizobacterial volatile organic compounds (VOCs) play an important role in the suppression of soil-borne phytopathogens. In this study, the VOCs produced by a soil-isolate, Bacillus subtilis FA26, were evaluated in vitro for their antibacterial activity against Clavibacter michiganensis ssp. sepedonicus (Cms), the causal agent of bacterial ring rot of potato. The VOCs emitted by FA26 inhibited the growth of Cms significantly compared with the control. Scanning and transmission electron microscopy analyses revealed distorted colony morphology and a wide range of abnormalities in Cms cells exposed to the VOCs of FA26. Varying the inoculation strategy and inoculum size showed that the production and activity of the antibacterial VOCs of FA26 were dependent on the culture conditions. Headspace solid-phase microextraction/gas chromatography-mass spectrometry analyses revealed that FA26 produced 11 VOCs. Four VOCs (benzaldehyde, nonanal, benzothiazole and acetophenone) were associated with the antibacterial activity against Cms. The results suggested that the VOCs produced by FA26 could control the causal agent of bacterial ring rot of potato. This information will increase our understanding of the microbial interactions mediated by VOCs in nature and aid the development of safer strategies for controlling plant disease.

[THE NATIONAL NUTRIENT MEDIUM FOR DIAGNOSTIC OF PURULENT BACTERIAL MENINGITIS].

PubMed

Podkopaev, Ya V; Domotenko, L V; Morozova, T P; Khramov, M K; Shepelin, A P

2015-05-01

The national growth mediums were developed for isolating and cultivating of main agents of purulent bacterial meningitis--haemophilus agar, chocolate agar, PBM-agar. The growing and selective characteristics of developed growth mediums are examined. The haemophilus agar ensures growth of Haemophilus influenzae. The chocolate agar, PBM-agar ensure growth of Neisseria meningitidis, Streptococcus pneumoniae and Haemophilus influenzae. By growing characteristics, the national growth mediums match foreign analogues. Under application of growth mediums with selective additions it is possible to achieve selective isolation of main agents of purulent bacterial meningitis with inhibition of growth of microbes-associates.

Bacterial contamination, bacterial profile and antimicrobial susceptibility pattern of isolates from stethoscopes at Jimma University Specialized Hospital.

PubMed

Shiferaw, Teklu; Beyene, Getenet; Kassa, Tesfaye; Sewunet, Tsegaye

2013-12-13

Hospital acquired infections are recognized as critical public health problems. Infections are frequently caused by organisms residing in healthcare environment, including contaminated medical equipment like Stethoscopes. To determine bacterial contamination, bacterial profile and anti-microbial susceptibility pattern of the isolates from stethoscopes at Jimma University Specialized Hospital. Cross-sectional study conducted from May to September 2011 at Jimma University Specialized Hospital. One hundred seventy-six stethoscopes owned by Health Care Workers (HCWs) and Medical students were randomly selected and studied. Self-administered structured questionnaire was used to collect socio-demographic data. Specimen was collected using moisten sterile cotton swab and 1 ml normal saline was used to transport the specimen, all laboratory investigations were done following standard microbiological techniques, at Microbiology Laboratory, Jimma University. SPSS windows version 16 used for data analysis and P <0.05 was considered statistically significant. A total, of 151 (85.8%) stethoscopes were contaminated. A total of 256 bacterial strains and a mean of 1.44×104 CFUs/diaphragm of stethoscopes was isolated. Of the 256 isolates, 133 (52%) were potential pathogens like S. aureus, Klebsiella spp., Citrobacter spp., Salmonella spp., Proteus spp., Enterobacter spp., P. aeruginosa and E. coli. All strains were resistant to multiple classes of antibiotics (two to eight classes of antibiotics). Disinfection practice was poor. Disinfection practice was found to be associated with bacterial contamination of stethoscopes (P < 0.05). High contamination rate 100 (90.9%) was observed among stethoscopes that had never been disinfected; while the least contamination 29 (72.2%) was found on those disinfected a week or less before the survey. Bacterial contamination of the stethoscope was significant. The isolates were potential pathogens and resistant to multiple classes of

Diarrheal diseases of infancy in Cali, Colombia: study design and summary report on isolated disease agents.

PubMed

Newell, K W; Dover, A S; Clemmer, D I; D'Alessandro, A; Duenas, A; Gracián, M; LeBlanc, D R

1976-01-01

For public health reasons, it is important that the etiologic agents of early childhood diarrhea be isolated and identified, and that their routes of transmission be defined. This is especially true in tropical and subtropical developing countries, where childhood patterns of exposure to diarrheal disease agents usually differ from those in developed countries, and where diarrheal illness is a frequent harbinger of death among children under five years of age. This artical describes a study designed to identify diarrheal disease agents and transmission patterns in Cali, a large city of western Colombia's fertile Cauca River Valley. The study area, composed of five working-class districts with a total population of some 40,000, appeared to provide an environment fairly similar to those of many other "average" working-class communities in Latin America. Beginning in July 1962, a cohort of 296 children being born in these districts was studied, the period of investigation starting with the date of birth and continuing until each child's second birthday or its premature withdrawal from the study. Weekly home visits were made to establish defecation patterns, feeding practices, and anthropometry. The resulting data were then analyzed in terms of defecation frequencies, occurrence of liquid stools, and the presence of blood, mucus, or pus in the stools. Differences were noted in male and female defecation patterns and in the defecation frequencies of different age groups. Stool specimens for bacteriologic, virologic, and parasitologic examination were collected monthly on a regular basis and weekly when diarrhea occurred. Numerically, viruses were isolated and identified more often than other agents. The most commonly isolated parasite species and viral and bacterial serotypes were G. lamblia (from 222 subjects), echovirus 11 (from 166 subjects), and enteropathogenic Escherichia coli 026:B6 (from 138 subjects). Compared with the findings of several studies in other

Spectrum and Sensitivity of Bacterial Keratitis Isolates in Auckland.

PubMed

Marasini, S; Swift, S; Dean, S J; Ormonde, S E; Craig, J P

2016-01-01

Background. The bacteria isolated from severe cases of keratitis and their antibiotic sensitivity are recognised to vary geographically and over time. Objectives. To identify the most commonly isolated bacteria in keratitis cases admitted over a 24-month period to a public hospital in Auckland, New Zealand, and to investigate in vitro sensitivity to antibiotics. Methods. Hospital admissions for culture-proven bacterial keratitis between January 2013 and December 2014 were identified. Laboratory records of 89 culture positive cases were retrospectively reviewed and antibiotic sensitivity patterns compared with previous studies from other NZ centres. Results. From 126 positive cultures, 35 species were identified. Staphylococcus was identified to be the most common isolate (38.2%), followed by Pseudomonas (21.3%). Over the last decade, infection due to Pseudomonas species, in the same setting, has increased (p ≤ 0.05). Aminoglycosides, cefazolin, ceftazidime, erythromycin, tetracycline, and doxycycline were 100% effective against tested isolates in vitro. Amoxicillin (41.6%), cefuroxime (33.3%), and chloramphenicol (94.7%) showed reduced efficacy against Gram-negative bacteria, whereas penicillin (51%) and ciprofloxacin (98.8%) showed reduced efficacy against Gram-positive bacteria. Conclusions. Despite a shift in the spectrum of bacterial keratitis isolates, antibiotic sensitivity patterns have generally remained stable and show comparability to results within the last decade from NZ centres.

Spectrum and Sensitivity of Bacterial Keratitis Isolates in Auckland

PubMed Central

Swift, S.; Dean, S. J.; Ormonde, S. E.

2016-01-01

Background. The bacteria isolated from severe cases of keratitis and their antibiotic sensitivity are recognised to vary geographically and over time. Objectives. To identify the most commonly isolated bacteria in keratitis cases admitted over a 24-month period to a public hospital in Auckland, New Zealand, and to investigate in vitro sensitivity to antibiotics. Methods. Hospital admissions for culture-proven bacterial keratitis between January 2013 and December 2014 were identified. Laboratory records of 89 culture positive cases were retrospectively reviewed and antibiotic sensitivity patterns compared with previous studies from other NZ centres. Results. From 126 positive cultures, 35 species were identified. Staphylococcus was identified to be the most common isolate (38.2%), followed by Pseudomonas (21.3%). Over the last decade, infection due to Pseudomonas species, in the same setting, has increased (p ≤ 0.05). Aminoglycosides, cefazolin, ceftazidime, erythromycin, tetracycline, and doxycycline were 100% effective against tested isolates in vitro. Amoxicillin (41.6%), cefuroxime (33.3%), and chloramphenicol (94.7%) showed reduced efficacy against Gram-negative bacteria, whereas penicillin (51%) and ciprofloxacin (98.8%) showed reduced efficacy against Gram-positive bacteria. Conclusions. Despite a shift in the spectrum of bacterial keratitis isolates, antibiotic sensitivity patterns have generally remained stable and show comparability to results within the last decade from NZ centres. PMID:27213052

NORMAL VAGINAL BACTERIAL FLORA OF GIANT PANDAS (AILUROPODA MELANOLEUCA) AND THE ANTIMICROBIAL SUSCEPTIBILITY PATTERNS OF THE ISOLATES.

PubMed

Yang, Xin; Yang, Jiang; Wang, Hongning; Li, Caiwu; He, Yongguo; Jin, SenYan; Zhang, Hemin; Li, Desheng; Wang, Pengyan; Xu, Yuesong; Xu, Changwen; Fan, Chengyun; Xu, Lulai; Huang, Shan; Qu, Chunmao; Li, Guo

2016-03-01

In order to study the typical vaginal bacterial flora of giant pandas (Ailuropoda melanoleuca), we took vaginal swabs for the sake of bacterial isolation, from 24 healthy female giant pandas. A total of 203 isolates were identified, representing a total of 17 bacterial species. The most common bacteria isolated were Lactobacillus spp. (54.2%, 13 of 24), followed by Staphylococcus epidermidis (41.7%, 10 of 24) and Escherichia coli (33.3%, 8 of 24). Some opportunistic pathogenic bacteria, such as Peptostreptococcus spp., Klebsiella pneumoniae, and Proteus mirabilis, were also isolated but showed no pathology. Antimicrobial susceptibility testing of aerobic bacterial isolates was performed with disk diffusion method. Of the 152 isolates, resistance was most frequently observed with chloramphenicol (17.8%), followed by tetracycline (14.5%), ciprofloxacin (12.5%), streptomycin (11.8%), and florfenicol (11.8%), while 7.2% were multidrug resistant. This is the first report of the normal vaginal culturable bacterial flora of giant pandas, followed by the antimicrobial susceptibility patterns of the isolates.

NORMAL VAGINAL BACTERIAL FLORA OF GIANT PANDAS (AILUROPODA MELANOLEUCA) AND THE ANTIMICROBIAL SUSCEPTIBILITY PATTERNS OF THE ISOLATES.

PubMed

Yang, Xin; Yang, Jiang; Wang, Hongning; Li, Caiwu; He, Yongguo; Jin, SenYan; Zhang, Hemin; Li, Desheng; Wang, Pengyan; Xu, Yuesong; Xu, Changwen; Fan, Chengyun; Xu, Lulai; Huang, Shan; Qu, Chunmao; Li, Guo

2016-06-01

To study the typical vaginal bacterial flora of giant pandas (Ailuropoda melanoleuca), we took vaginal swabs for the sake of bacterial isolation, from 24 healthy female giant pandas. A total of 203 isolates were identified, representing a total of 17 bacterial species. The most common bacteria isolated were Lactobacillus spp. (54.2%, 13/24), followed by Staphylococcus epidermidis (41.7%, 10/24) and Escherichia coli (33.3%, 8/24). Some opportunistic pathogenic bacteria, such as Peptostreptococcus spp., Klebsiella pneumoniae , and Proteus mirabilis , were also isolated but showed no pathology. Antimicrobial susceptibility testing of aerobic bacterial isolates was performed with the disk diffusion method. Of the 152 isolates, resistance was most frequently observed with chloramphenicol (17.8%), followed by tetracycline (14.5%), ciprofloxacin (12.5%), streptomycin (11.8%), and florfenicol (11.8%), whereas 7.2% were multidrug resistant. This is the first report of the normal culturable vaginal bacterial flora of giant pandas and the antimicrobial susceptibility patterns of the isolates.

Bacterial and fungal keratitis in Upper Egypt: In vitro screening of enzymes, toxins and antifungal activity

PubMed Central

Gharamah, Abdullah A; Moharram, Ahmed M; Ismail, Mady A; AL-Hussaini, Ashraf K

2014-01-01

Purpose: This work was conducted to study the ability of bacterial and fungal isolates from keratitis cases in Upper Egypt to produce enzymes, toxins, and to test the isolated fungal species sensitivity to some therapeutic agents. Materials and Methods: One hundred and fifteen patients clinically diagnosed to have microbial keratitis were investigated. From these cases, 37 bacterial isolates and 25 fungal isolates were screened for their ability to produce extra-cellular enzymes in solid media. In addition, the ability of fungal isolates to produce mycotoxins and their sensitivity to 4 antifungal agents were tested. Results: Protease, lipase, hemolysins, urease, phosphatase, and catalase were detected respectively in 48.65%, 37.84%, 59.46%, 43.24%, 67.57%, and 100% out of 37 bacterial isolates tested. Out of 25 fungal isolates tested during the present study, 80% were positive for protease, 84% for lipase and urease, 28% for blood hemolysis, and 100% for phosphatase and catalase enzymes. Thirteen fungal isolates were able to produce detectable amounts of 7 mycotoxins in culture medium (aflatoxins (B1, B2, G1, and G2), sterigmatocystin, fumagillin, diacetoxyscirpenol, zearalenone, T-2 toxin, and trichodermin). Among the antifungal agents tested in this study, terbinafine showed the highest effect against most isolates in vitro. Conclusion: In conclusion, the ability of bacterial and fungal isolates to produce extracellular enzymes and toxins may be aid in the invasion and destruction of eye tissues, which, in turn, lead to vision loss. PMID:24008795

Rapid polymerase chain reaction-based screening assay for bacterial biothreat agents.

PubMed

Yang, Samuel; Rothman, Richard E; Hardick, Justin; Kuroki, Marcos; Hardick, Andrew; Doshi, Vishal; Ramachandran, Padmini; Gaydos, Charlotte A

2008-04-01

To design and evaluate a rapid polymerase chain reaction (PCR)-based assay for detecting Eubacteria and performing early screening for selected Class A biothreat bacterial pathogens. The authors designed a two-step PCR-based algorithm consisting of an initial broad-based universal detection step, followed by specific pathogen identification targeted for identification of the Class A bacterial biothreat agents. A region in the bacterial 16S rRNA gene containing a highly variable sequence flanked by clusters of conserved sequences was chosen as the target for the PCR assay design. A previously described highly conserved region located within the 16S rRNA amplicon was selected as the universal probe (UniProbe, Integrated DNA Technology, Coralville, IA). Pathogen-specific TaqMan probes were designed for Bacillus anthracis, Yersinia pestis, and Francisella tularensis. Performance of the assay was assessed using genomic DNA extracted from the aforementioned biothreat-related organisms (inactivated or surrogate) and other common bacteria. The UniProbe detected the presence of all tested Eubacteria (31/31) with high analytical sensitivity. The biothreat-specific probes accurately identified organisms down to the closely related species and genus level, but were unable to discriminate between very close surrogates, such as Yersinia philomiragia and Bacillus cereus. A simple, two-step PCR-based assay proved capable of both universal bacterial detection and identification of select Class A bacterial biothreat and biothreat-related pathogens. Although this assay requires confirmatory testing for definitive species identification, the method has great potential for use in ED-based settings for rapid diagnosis in cases of suspected Category A bacterial biothreat agents.

Enterobacter and Klebsiella species isolated from fresh vegetables marketed in Valencia (Spain) and their clinically relevant resistances to chemotherapeutic agents.

PubMed

Falomir, María Pilar; Rico, Hortensia; Gozalbo, Daniel

2013-12-01

Occurrence of antibiotic-resistant pathogenic or commensal enterobacteria in marketed agricultural foodstuffs may contribute to their incorporation into the food chain and constitutes an additional food safety concern. In this work, we have determined the clinically relevant resistances to 11 common chemotherapeutic agents in Enterobacter and Klebsiella isolates from fresh vegetables from various sources (supermarkets and greengrocers' shops in Valencia, Spain). A total of 96 isolates were obtained from 160 vegetables analyzed (50% positive samples): 68 Enterobacter isolates (59 E. cloacae, two E. aerogenes, two E. cancerogenus, one E. gergoviae, and four E. sakazakii, currently Cronobacter spp.), and 28 Klebsiella isolates (19 K. oxytoca and 9 K. pneumoniae). Only seven isolates were susceptible to all agents tested, and no resistances to ceftazidime, ciprofloxacin, gentamicin, and chloramphenicol were detected. Most isolates were resistant to amoxicillin/clavulanic acid (74 [58 Enterobacter and 16 Klebsiella]) or to ampicillin (80 [55/25]). Other resistances were less frequent: nitrofurantoin (13 isolates [12/1]), tetracycline (6 [5/1]), co-trimoxazole (3 [3/0]), cefotaxime (1 [1/0]), and streptomycin (2 [1/1]). Multiresistant isolates to two (56 [41/15]), three (10 E. cloacae isolates), four (one E. cloacae and one K. pneumoniae isolate), and five (two E. cloacae isolates) chemotherapeutic agents were also detected. The presence of potential pathogens points to marketed fresh produce, which often is eaten raw, as a risk factor for consumer health. In addition, these results support the usefulness of these bacterial species as indicators of the spreading of antibiotic resistances into the environment, particularly in the food chain, and suggest their role as carriers of resistance determinants from farms to consumers, which may constitute an additional "silent" food safety concern. Therefore, there is a need to improve the hygienic quality of marketed fresh

Bacterial contamination, bacterial profile and antimicrobial susceptibility pattern of isolates from stethoscopes at Jimma University Specialized Hospital

PubMed Central

2013-01-01

Introduction Hospital acquired infections are recognized as critical public health problems. Infections are frequently caused by organisms residing in healthcare environment, including contaminated medical equipment like Stethoscopes. Objective To determine bacterial contamination, bacterial profile and anti-microbial susceptibility pattern of the isolates from stethoscopes at Jimma University Specialized Hospital. Methodology Cross-sectional study conducted from May to September 2011 at Jimma University Specialized Hospital. One hundred seventy-six stethoscopes owned by Health Care Workers (HCWs) and Medical students were randomly selected and studied. Self-administered structured questionnaire was used to collect socio-demographic data. Specimen was collected using moisten sterile cotton swab and 1 ml normal saline was used to transport the specimen, all laboratory investigations were done following standard microbiological techniques, at Microbiology Laboratory, Jimma University. SPSS windows version 16 used for data analysis and P <0.05 was considered statistically significant. Result: A total, of 151 (85.8%) stethoscopes were contaminated. A total of 256 bacterial strains and a mean of 1.44×104 CFUs/diaphragm of stethoscopes was isolated. Of the 256 isolates, 133 (52%) were potential pathogens like S. aureus, Klebsiella spp., Citrobacter spp., Salmonella spp., Proteus spp., Enterobacter spp., P. aeruginosa and E. coli. All strains were resistant to multiple classes of antibiotics (two to eight classes of antibiotics). Disinfection practice was poor. Disinfection practice was found to be associated with bacterial contamination of stethoscopes (P < 0.05). High contamination rate 100 (90.9%) was observed among stethoscopes that had never been disinfected; while the least contamination 29 (72.2%) was found on those disinfected a week or less before the survey. Conclusion Bacterial contamination of the stethoscope was significant. The isolates were potential

Plasmid profiling of bacterial isolates from confined environments

NASA Astrophysics Data System (ADS)

van Houdt, Rob; Provoost, Ann; Coninx, Ilse; Leys, Natalie; Mergeay, Max

Plasmid profiling of bacterial isolates from confined environments R. Van Houdt, I. Coninx, A. Provoost, N. Leys, and M. Mergeay Expertise group for Molecular and Cellular Biology, Institute for Environment, Health and Safety, Belgian Nuclear Research Centre (SCK•CEN), Boeretang 200, B-2400 Mol, Belgium. Human exploration of extreme and isolated hostile environments such as space requires special confined small volume habitats to protect and house the crew. However, human confinement in such small volume habitats has restrictions on waste disposal and personal hygiene and inevitably generates a particular community of microorganisms within the habitat. These microorganisms are mainly originating from the crew (skin, mucous membranes, upper respiratory tract, mouth, and gastrointestinal tract) but also include the residing environmental microorganisms. Earth-based confined habitats such as the Antarctic Research Station Concordia are used as test beds for long-duration spaceflights to study the physiologic and psychological adaptation to isolated environments. The dynamics of the environmental microbial population in such a test bed could render additional insights in assessing the potential health risks in long-duration space missions. Not only total bacterial contamination levels are important, but it is essential to identify also the predominant microbial taxa and their mobile genetic elements (MGE). These MGEs could be exchanged between bacteria by horizontal gene transfer and may alter the pathogenic potential since they often carry antibiotic resistance or more in general adaptation-enhancing traits. In this study several bacterial strains isolated in the Concordia research station were examined for their plasmid content. An optimized protocol for extraction of large plasmids showed the present of at least one plasmid in 50% of the strains. For all strains the minimal inhibitory concentration of a range of antibiotics was determined indicating resistance to

Draft Genome Sequence of Two Strains of Xanthomonas arboricola Isolated from Prunus persica Which Are Dissimilar to Strains That Cause Bacterial Spot Disease on Prunus spp.

PubMed Central

Garita-Cambronero, Jerson; Palacio-Bielsa, Ana; López, María M.

2016-01-01

The draft genome sequences of two strains of Xanthomonas arboricola, isolated from asymptomatic peach trees in Spain, are reported here. These strains are avirulent and do not belong to the same phylogroup as X. arboricola pv. pruni, a causal agent of bacterial spot disease of stone fruits and almonds. PMID:27609931

Isolation of a lead tolerant novel bacterial species, Achromobacter sp. TL-3: assessment of bioflocculant activity.

PubMed

Batta, Neha; Subudhi, Sanjukta; Lal, Banwari; Devi, Arundhuti

2013-11-01

Lead is one of the four heavy metals that has a profound damaging effects on human health. In the recent past there has been an increasing global concern for development of sustainable bioremediation technologies for detoxification of lead contaminant. Present investigation highlights for lead biosorption by a newly isolated novel bacterial species; Achromobacter sp. TL-3 strain, isolated from activated sludge samples contaminated with heavy metals (collected from oil refinery, Assam, North-East India). For isolation of lead tolerant bacteria, sludge samples were enriched into Luria Broth medium supplemented separately with a range of lead nitrate; 250, 500, 750, 1000, 1250 and 1500 ppm respectively. The bacterial consortium that could tolerate 1500 ppm of lead nitrate was selected further for purification of lead tolerant bacterial isolates. Purified lead tolerant bacterial isolates were then eventually inoculated into production medium supplemented with ethanol and glycerol as carbon and energy source to investigate for bioflocculant production. Bioflocculant production was estimated by monitoring the potential of lead tolerant bacterial isolate to flocculate Kaolin clay in presence of 1% CaCl2. Compared to other isolates, TL-3 isolate demonstrated for maximum bioflocculant activity of 95% and thus was identified based on 16S rRNA gene sequence analysis. TL3 isolate revealed maximum homology (98%) with Achromobacter sp. and thus designated as Achromobacter sp. TL-3. Bioflocculant activity of TL-3 isolate was correlated with the change in pH and growth. Achromobacter sp. TL-3 has significant potential for lead biosorption and can be effectively employed for detoxification of lead contaminated waste effluents/waste waters.

Isolation and identification of bacterial endophytes from grasses along the Oregon coast

USDA-ARS?s Scientific Manuscript database

Bacterial endophytes have been shown to improve abiotic and biotic stress responses in plants. Grasses growing along the Oregon coast are exposed to harsh conditions and may harbor endophytes that enable them to survive and grow under these conditions. Bacterial endophytes were isolated from thirty-...

Isolation of bacterial cellulose nanocrystalline from pineapple peel waste: Optimization of acid concentration in the hydrolysis method

NASA Astrophysics Data System (ADS)

Anwar, Budiman; Rosyid, Nurul Huda; Effendi, Devi Bentia; Nandiyanto, Asep Bayu Dani; Mudzakir, Ahmad; Hidayat, Topik

2016-02-01

Isolation of needle-shaped bacterial cellulose nanocrystalline with a diameter of 16-64 nm, a fiber length of 258-806 nm, and a degree of crystallinity of 64% from pineapple peel waste using an acid hydrolysis process was investigated. Experimental showed that selective concentration of acid played important roles in isolating the bacterial cellulose nanocrystalline from the cellulose source. To achieve the successful isolation of bacterial cellulose nanocrystalline, various acid concentrations were tested. To confirm the effect of acid concentration on the successful isolation process, the reaction conditions were fixed at a temperature of 50°C, a hydrolysis time of 30 minutes, and a bacterial cellulose-to-acid ratio of 1:50. Pineapple peel waste was used as a model for a cellulose source because to the best of our knowledge, there is no report on the use of this raw material for producing bacterial cellulose nanocrystalline. In fact, this material can be used as an alternative for ecofriendly and cost-free cellulose sources. Therefore, understanding in how to isolate bacterial cellulose nanocrystalline from pineapple peel waste has the potential for large-scale production of inexpensive cellulose nanocrystalline.

Bacterial meningitis - principles of antimicrobial treatment.

PubMed

Jawień, Miroslaw; Garlicki, Aleksander M

2013-01-01

Bacterial meningitis is associated with significant morbidity and mortality despite the availability of effective antimicrobial therapy. The management approach to patients with suspected or proven bacterial meningitis includes emergent cerebrospinal fluid analysis and initiation of appropriate antimicrobial and adjunctive therapies. The choice of empirical antimicrobial therapy is based on the patient's age and underlying disease status; once the infecting pathogen is isolated, antimicrobial therapy can be modified for optimal treatment. Successful treatment of bacterial meningitis requires the knowledge on epidemiology including prevalence of antimicrobial resistant pathogens, pathogenesis of meningitis, pharmacokinetics and pharmacodynamics of antimicrobial agents. The emergence of antibiotic-resistant bacterial strains in recent years has necessitated the development of new strategies for empiric antimicrobial therapy for bacterial meningitis.

Bacterial RNA isolation.

PubMed

Ares, Manuel

2012-09-01

In this bacterial RNA isolation protocol, an "RNA-protective" treatment is followed by lysozyme digestion of the peptidoglycan component of the cell wall. EDTA promotes the loss of the outer membrane of Gram-negative bacteria and allows the lysozyme better access to the peptidoglycan. Cells begin to lyse during digestion in hypotonic lysozyme buffer and lysis is completed by sodium dodecyl sulfate (SDS) and hot phenol:chloroform:isoamyl alcohol (PCA) extraction. SDS and hot phenol disrupt membranes, denature protein (including RNase), and strip proteins from RNA. The separation of the organic phase from the aqueous phase is achieved using Phase Lock Gel, an inert material with a density intermediate between the organic and aqueous samples. The sample is split into three phases: from bottom to top, these are phenol and chloroform (organic phase), the inert gel with the interface material, and the aqueous phase with the RNA. The gel acts as a physical barrier between the sample and the organic phase plus interface. Following organic extraction, the RNA is concentrated by ethanol precipitation.

[Polyvalence of bacteriophages isolated from fruit trees, affected by bacterial fire blight].

PubMed

Tovkach, F I; Moroz, S N; Korol', N A; Faĭdiuk, Iu V; Kushkina, A I

2013-01-01

Phage populations appearing as a result of a pathogenic process caused by Erwinia amylovora have been discovered and described. They accompany bacterial fire blight development in the process of quince, pear and apple trees vegetation in Zakarpattya region of Ukraine. Phage isolates of the affected pear and quince include polyvalent virulent phages able to develop on bacterial strains associated with plants--E. amylovora. E. "horticola" and Pantoea agglomerans. E. amylovora isolated from the plant tissues affected by the fire blight and detected at the same time as phages proved to be resistant to the viral infection. It is hard to explain now this characteristic however it was noticed that resistance to phages can change drastically in case of dissociation, lysogenization and mutagenesis of erwinia in laboratory conditions. Phage population study shows that they are heterogeneous and can obviously include not only polyvalent but also specific viruses. Further studies of biology and molecular genetics of pure lines of isolated phages will help to get closer to understanding the place and role of bacteriophages in the complicated network of relations between bacterial pathogens and plants.

Bacterial and fungal endophthalmitis in upper Egypt: related species and risk factors.

PubMed

Gharamah, A A; Moharram, A M; Ismail, M A; Al-Hussaini, A K

2012-08-01

To study risk factors, contributing factors of bacterial and fungal endophthalmitis in Upper Egypt, test the isolated species sensitive to some therapeutic agents, and to investigate the air-borne bacteria and fungi in opthalmology operating rooms. Thirty one cases of endophthalmitis were clinically diagnosed and microbiologically studied. Indoor air-borne bacteria and fungi inside four air-conditioned operating rooms in the Ophthalmology Department at Assiut University Hospitals were also investigated. The isolated microbes from endophthalmitis cases were tested for their ability to produce some extracellular enzymes including protease, lipase, urease, phosphatase and catalase. Also the ability of 5 fungal isolates from endophthalmitis origin to produce mycotoxins and their sensitivity to some therapeutic agents were studied. Results showed that bacteria and fungi were responsihle for infection in 10 and 6 cases of endophthalmitis, respectively and only 2 cases produced a mixture of bacteria and fungi. Trauma was the most prevalent risk factor of endophthalmitis where 58.1% of the 31 cases were due to trauma. In ophthalmology operating rooms, different bacterial and fungal species were isolated. 8 bacterial and 5 fungal isolates showed their ability to produce enzymes while only 3 fungal isolates were able to produce mycotoxins. Terbinafine showed the highest effect against most isolates in vitro. The ability of bacterial and fungal isolates to produce extracellular enzymes and mycotoxins may be aid in the invasion and destruction of eye tissues. Microbial contamination of operating rooms with air-borne bacteria and fungi in the present work may be a source of postoperative endophthalmitis.

Oxabicyclooctane-Linked Novel Bacterial Topoisomerase Inhibitors as Broad Spectrum Antibacterial Agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Sheo B.; Kaelin, David E.; Wu, Jin

Bacterial resistance is eroding the clinical utility of existing antibiotics necessitating the discovery of new agents. Bacterial type II topoisomerase is a clinically validated, highly effective, and proven drug target. This target is amenable to inhibition by diverse classes of inhibitors with alternative and distinct binding sites to quinolone antibiotics, thus enabling the development of agents that lack cross-resistance to quinolones. Described here are novel bacterial topoisomerase inhibitors (NBTIs), which are a new class of gyrase and topo IV inhibitors and consist of three distinct structural moieties. The substitution of the linker moiety led to discovery of potent broad-spectrum NBTIsmore » with reduced off-target activity (hERG IC50 > 18 μM) and improved physical properties. AM8191 is bactericidal and selectively inhibits DNA synthesis and Staphylococcus aureus gyrase (IC50 = 1.02 μM) and topo IV (IC50 = 10.4 μM). AM8191 showed parenteral and oral efficacy (ED50) at less than 2.5 mg/kg doses in a S. aureus murine infection model. A cocrystal structure of AM8191 bound to S. aureus DNA-gyrase showed binding interactions similar to that reported for GSK299423, displaying a key contact of Asp83 with the basic amine at position-7 of the linker.« less

Characterization of bacterial etiologic agents of biofilm formation in medical devices in critical care setup.

PubMed

Revdiwala, Sangita; Rajdev, Bhaumesh M; Mulla, Summaiya

2012-01-01

Background. Biofilms contaminate catheters, ventilators, and medical implants; they act as a source of disease for humans, animals, and plants. Aim. Critical care units of any healthcare institute follow various interventional strategies with use of medical devices for the management of critical cases. Bacteria contaminate medical devices and form biofilms. Material and Methods. The study was carried out on 100 positive bacteriological cultures of medical devices which were inserted in hospitalized patients. The bacterial isolates were processed as per microtitre plate. All the isolates were subjected to antibiotic susceptibility testing by VITEK 2 compact automated systems. Results. Out of the total 100 bacterial isolates tested, 88 of them were biofilm formers. A 16-20-hour incubation period was found to be optimum for biofilm development. 85% isolates were multidrug resistants and different mechanisms of bacterial drug resistance like ESBL, carbapenemase, and MRSA were found among isolates. Conclusion. Availability of nutrition in the form of glucose enhances the biofilm formation by bacteria. Time and availability of glucose are important factors for assessment of biofilm progress. It is an alarm for those who are associated with invasive procedures and indwelling medical devices especially in patients with low immunity.

Fluoroquinolone Treatment and Susceptibility of Isolates From Bacterial Keratitis

PubMed Central

Ray, Kathryn J.; Prajna, Lalitha; Srinivasan, Muthiah; Geetha, Manoharan; Karpagam, Rajarathinam; Glidden, David; Oldenburg, Catherine E.; Sun, Catherine Q.; McLeod, Stephen D.; Acharya, Nisha R.; Lietman, Thomas M.

2013-01-01

Objective To analyze the relationship between fluoroquinolone use at presentation and minimum inhibitory concentration in bacterial keratitis. Methods The Steroids for Corneal Ulcers Trial was a randomized, double-masked, placebo-controlled trial assessing the effect of adjunctive topical corticosteroid treatment on outcomes in bacterial keratitis. After presentation, all patients were treated with moxifloxacin hydrochloride, 0.5%. We compare antibiotic use at presentation with minimum inhibitory concentration against moxifloxacin for all isolates. Separate analyses accounted for organism species and fluoroquinolone generation. Results Topical fluoroquinolone use at presentation was reported in 92 of 480 cases (19.2%). Causative organisms in the 480 cases included Streptococcus pneumoniae (247 cases [51.5%]), Pseudomonas aeruginosa (109 cases [22.7%]), and Nocardia species (55 cases [11.5%]). Isolates from patients who reported fluoroquinolone use at presentation had a 2.01-fold–higher minimum inhibitory concentration (95% CI, 1.39-fold to 2.91-fold; P <.001). Fourth-generation fluoroquinolones were associated with a 3.48-fold–higher minimum inhibitory concentration than those isolates that were not exposed to pretreatment at enrollment (95% CI, 1.99-fold to 6.06-fold; P <.001). Conclusion This study provides evidence that prior use of fluoroquinolones is associated with antibiotic resistance. PMID:23307105

Fluoroquinolone treatment and susceptibility of isolates from bacterial keratitis.

PubMed

Ray, Kathryn J; Prajna, Lalitha; Srinivasan, Muthiah; Geetha, Manoharan; Karpagam, Rajarathinam; Glidden, David; Oldenburg, Catherine E; Sun, Catherine Q; McLeod, Stephen D; Acharya, Nisha R; Lietman, Thomas M

2013-03-01

To analyze the relationship between fluoroquinolone use at presentation and minimum inhibitory concentration in bacterial keratitis. The Steroids for Corneal Ulcers Trial was a randomized, double-masked, placebo-controlled trial assessing the effect of adjunctive topical corticosteroid treatment on outcomes in bacterial keratitis. After presentation, all patients were treated with moxifloxacin hydrochloride, 0.5%. We compare antibiotic use at presentation with minimum inhibitory concentration against moxifloxacin for all isolates. Separate analyses accounted for organism species and fluoroquinolone generation. Topical fluoroquinolone use at presentation was reported in 92 of 480 cases (19.2%). Causative organisms in the 480 cases included Streptococcus pneumoniae (247 cases [51.5%]), Pseudomonas aeruginosa (109 cases [22.7%]), and Nocardia species (55 cases [11.5%]). Isolates from patients who reported fluoroquinolone use at presentation had a 2.01-fold-higher minimum inhibitory concentration (95% CI, 1.39-fold to 2.91-fold; P < .001). Fourth-generation fluoroquinolones were associated with a 3.48-fold-higher minimum inhibitory concentration than those isolates that were not exposed to pretreatment at enrollment (95% CI, 1.99-fold to 6.06-fold; P < .001). This study provides evidence that prior use of fluoroquinolones is associated with antibiotic resistance. clinicaltrials.gov Identifier: NCT00324168.

Bacterial agents as a cause of infertility in humans.

PubMed

Ruggeri, Melania; Cannas, Sara; Cubeddu, Marina; Molicotti, Paola; Piras, Gennarina Laura; Dessole, Salvatore; Zanetti, Stefania

2016-07-01

Infertility is a problem affecting almost 15% of couples. There are many causes for this condition, among which urogenital bacterial infections seem to play an important role. Many studies have explained the mechanisms by which bacteria cause infertility both in men and women. Therefore we undertook this study to evaluate the presence of genito-urinary infections in infertile couples who sought counselling to investigate their condition. Microbiological analysis was performed on semen and vaginal/cervical samples of both partners of each couple. The percentage of individuals affected by a urogenital bacterial infection was between 14 and 20%. More significantly, most of the species isolated both in men and women have been described in the literature as potential causes of infertility.

Suppression of Bacterial Wilt and Fusarium Wilt by a Burkholderia nodosa Strain Isolated from Kalimantan Soils, Indonesia.

PubMed

Nion, Yanetri Asi; Toyota, Koki

2008-01-01

A trial was conducted to suppress bacterial wilt of tomato (BWT) caused by Ralstonia solanacearum using biocontrol agents (BCAs) isolated from soils in Kalimantan, Indonesia. Five isolates were selected from 270 isolates as better performing BCAs through screening four times using a pumice medium. The isolates selected were identified as Burkholderia nodosa, Burkholderia sacchari, Burkholderia pyrrocinia and Burkholderia terricola according to 16S rDNA sequences, fatty acid composition and carbon source utilization patterns. Among them, B. nodosa G5.2.rif1 had significant suppressive effects on Fusarium wilt of tomato (FWT) and spinach (FWS) as well as BWT. When B. nodosa G5.2rif1 was inoculated into a pumice medium in combination with sucrose, it showed even more stable disease suppression for BWT, but not for FWS. This suppression was considered to mainly occur through competition for nutrients. In two times greenhouse experiments for BWT using pots comparable in size to those used commercially, B. nodosa G5.2rif1 significantly suppressed the disease index by 33-79%, with no inhibitory effects on the growth, yield and quality of tomatoes.

Bacterial Coaggregation and Cohesion Among Isolates From Contact Lens Cases.

PubMed

Datta, Ananya; Stapleton, Fiona; Willcox, Mark D P

2018-06-01

The aim of this study was to examine cohesion, coaggregation, and coculture between bacteria commonly isolated from contact lens cases. Staphylococcus epidermidis, Staphylococcus haemolyticus, Micrococcus luteus, and Acinetobacter radioresistens (two strains each) isolated from contact lens cases of two asymptomatic wearers were used in this study. In the cohesion assay, bacteria were grown, washed, and examined by incubating lens cases with two different types of bacteria sequentially and assessing the number of adhered cells of each isolate. The ability of isolates to interfere with the growth of other isolates was tested by growing strains in cocultures for 24 hours and determining the numbers of cells of individual strains. For coaggregation, equal proportions of two bacterial suspensions were mixed and allowed to coaggregate for 24 hours. Inhibition of coaggregation was tested by the addition of lactose (0.06 M) or sucrose (0.06 M) or pronase. The initial adhesion of M. luteus or A. radioresistens significantly (P < 0.05) enhanced the subsequent adhesion of the staphylococci. The addition of A. radioresistens in liquid media significantly (P < 0.05) enhanced the growth of staphylococci. S. epidermidis or S. haemolyticus coaggregated with M. luteus or A. radioresistens. The degree of coaggregation varied between 30% and 54%. The highest coaggregation (54% ± 5%) was seen between A. radioresistens 22-1 and S. epidermidis 22-1, isolated from the same lens case. Only lactose or sucrose treatment of staphylococci could partly inhibit coaggregation of some pairs. Coaggregation, cohesion, and growth promotion may facilitate the process of bacterial colonization of contact lens cases.

Comparing genome versus proteome-based identification of clinical bacterial isolates.

PubMed

Galata, Valentina; Backes, Christina; Laczny, Cédric Christian; Hemmrich-Stanisak, Georg; Li, Howard; Smoot, Laura; Posch, Andreas Emanuel; Schmolke, Susanne; Bischoff, Markus; von Müller, Lutz; Plum, Achim; Franke, Andre; Keller, Andreas

2018-05-01

Whole-genome sequencing (WGS) is gaining importance in the analysis of bacterial cultures derived from patients with infectious diseases. Existing computational tools for WGS-based identification have, however, been evaluated on previously defined data relying thereby unwarily on the available taxonomic information.Here, we newly sequenced 846 clinical gram-negative bacterial isolates representing multiple distinct genera and compared the performance of five tools (CLARK, Kaiju, Kraken, DIAMOND/MEGAN and TUIT). To establish a faithful 'gold standard', the expert-driven taxonomy was compared with identifications based on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) analysis. Additionally, the tools were also evaluated using a data set of 200 Staphylococcus aureus isolates.CLARK and Kraken (with k =31) performed best with 626 (100%) and 193 (99.5%) correct species classifications for the gram-negative and S. aureus isolates, respectively. Moreover, CLARK and Kraken demonstrated highest mean F-measure values (85.5/87.9% and 94.4/94.7% for the two data sets, respectively) in comparison with DIAMOND/MEGAN (71 and 85.3%), Kaiju (41.8 and 18.9%) and TUIT (34.5 and 86.5%). Finally, CLARK, Kaiju and Kraken outperformed the other tools by a factor of 30 to 170 fold in terms of runtime.We conclude that the application of nucleotide-based tools using k-mers-e.g. CLARK or Kraken-allows for accurate and fast taxonomic characterization of bacterial isolates from WGS data. Hence, our results suggest WGS-based genotyping to be a promising alternative to the MS-based biotyping in clinical settings. Moreover, we suggest that complementary information should be used for the evaluation of taxonomic classification tools, as public databases may suffer from suboptimal annotations.

Bacillus subtilis vegetative isolate surviving chlorine dioxide exposure: an elusive mechanism of resistance.

PubMed

Martin, D J H; Wesgate, R L; Denyer, S P; McDonnell, G; Maillard, J-Y

2015-12-01

Oxidizing agents such as chlorine dioxide are widely used microbicides, including for disinfection of medical equipment. We isolated a Bacillus subtilis isolate from a washer-disinfector whose vegetative form demonstrated unique resistance to chlorine dioxide (0·03%) and hydrogen peroxide (7·5%). The aim of this study was to understand the mechanisms of resistance expressed by this isolate. A range of resistance mechanisms were investigated in the B. subtilis isolate and a reference B. subtilis strain (ATCC 6051) to include bacterial cell aggregation, the presence of profuse exopolysaccharide (EPS), and the expression of detoxification enzymes. The basis of resistance of the isolate to high concentrations of oxidizing agents was not linked to the presence of endospores. Although, the presence of EPS, aggregation and expression of detoxification enzymes may play a role in bacterial survival to low concentrations of chlorine dioxide, it is unlikely that the mechanisms helped tested to survive the bactericidal effect of higher oxidizer concentrations. Overall, the mechanisms conferring resistance to chlorine dioxide and hydrogen peroxide remains elusive. Based on recent advances in the mode of action of oxidizing agents and notably hydrogen peroxide, we postulate that additional efficient intracellular mechanisms may be involved to explain significant resistance to in-use concentrations of commonly used high-level disinfectants. The isolation of a highly resistant vegetative Gram-positive bacterium to a highly reactive oxidizing agent is worrying. Understanding the mechanisms conferring such resistance is essential to effectively control such bacterial isolates. Here, we postulate that there are still mechanisms of bacterial resistance that have not been fully characterized. © 2015 The Authors published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.

[The combination effects of antibacterial agents against clinical isolated multiple-drug resistant Pseudomonas aeruginosa].

PubMed

Maesaki, Shigefumi; Yamaguchi, Toshiyuki; Sasaki, Kazumasa; Hashikita, Giichi; Shibuya, Shunsuke; Watanabe, Masaharu; Takayama, Sadao; Kawakami, Sayoko; Nagasawa, Mitsuaki; Suzuki, Noriyasu; Uchida, Takashi; Okabe, Tadashi; Kobayashi, Sugako

2006-02-01

The effectiveness of antibacterial agents against 70 strains of clinically isolated multiple-drug resistant Pseudomonas aeruginosa (MDRP) was measured by the micro dilution method. Fifty of all strains (71%) produced metallo-beta-lactamase and the IMP-1 gene was detected by polymerase chain reaction (PCR). The MIC90 (the minimum inhibitory concentration of an antibiotic necessary to inhibit the growth of 90% of bacterial strains) values of biapenem (BIPM), meropenem (MEPM), tazobactam/piperacillin (TAZ/PIPC), sulbactam/ cefoperazone (SBT/CPZ), cefepime (CFPM), ciprofloxacin (CPFX), pazufloxacin (PZFX), amikacin (AMK) and aztreonam (AZT) were found to be 265, 512, 256, 512, 512, 64, 128, 128 and 128 microg/mL, respectively. The in vitro combination effects of antibacterial agents were examined against 62 strains of MDRP and the synergy or additive effects were evaluated by fractional inhibitory concentration (FIC) index calculated by the checkerboard method. The combination of AMK and AZT showed synergy effects on 15/59 (25.4%) strains of MDRP. The synergy and additive effects on the MDRP strains were also found by the other antibacterial agents combination such as TAZ/PIPC and AMK, CFPM and AMK, and SBT/CPZ and AZT. These results suggested the necessity of further investigation of clinical usefulness.

Preponderance of bacterial isolates in urine of HIV-positive malaria-infected pregnant women with urinary tract infection.

PubMed

Ako-Nai, Kwashie Ajibade; Ebhodaghe, Blessing Itohan; Osho, Patrick; Adejuyigbe, Ebun; Adeyemi, Folasade Mubiat; Kassim, Olakunle O

2014-12-15

This study examined HIV and malaria co-infection as a risk factor for urinary tract infections (UTIs) in pregnancy. The study group included 74 pregnant women, 20 to 42 years of age, who attended the antenatal clinic at the Specialist Hospital at Akure, Ondo State, Nigeria. Forty-four of the pregnant women were either HIV seropositive with malaria infection (HIV+Mal+) or HIV seropositive without malaria (HIV+Mal-). The remaining thirty pregnant women served as controls and included women HIV seronegative but with malaria (HIV-Mal+) and women HIV seronegative without malaria. UTI was indicated by a bacterial colony count of greater than 10⁵/mL of urine, using cysteine lactose electrolyte deficient medium (CLED) as the primary isolation medium. Bacterial isolates were characterized using convectional bacteriological methods, and antibiotics sensitivity tests were carried out using the disk diffusion method. A total of 246 bacterial isolates were recovered from the cultures, with a mean of 3.53 isolates per subject. Women who were HIV+Mal+ had the most diverse group of bacterial isolates and the highest frequency of UTIs. The bacterial isolates from the HIV+Mal+ women also showed the highest degree of antibiotic resistance. While pregnancy and HIV infection may each represent a risk factor for UTI, HIV and malaria co-infection may increase its frequency in pregnancy. The higher frequency of multiple antibiotic resistance observed among the isolates, particularly isolates from HIV+Mal+ subjects, poses a serious public health concern as these strains may aggravate the prognosis of both UTI and HIV infection.

Chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of animal bacterial pathogens.

PubMed

Ebrahimi, Azizollah; Hemati, Majid; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Khoshnood, Sheida; Khubani, Shahin; Dokht Faraj, Mahdi; Hakimi Alni, Reza

2014-05-01

To study chlorhexidine digluconate disinfectant effects on planktonic growth and biofilm formation in some bacterial field isolates from animals. The current study investigated chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of veterinary bacterial pathogens. Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus. aureus and Streptococcus agalactiae (10 isolates for each) were examined for chlorhexidine digluconate effects on biofilm formation and planktonic growth using microtiter plates. In all of the examined strains in the presence of chlorhexidine digluconate, biofilm development and planktonic growth were affected at the same concentrations of the disinfectant. Chlorhexidine digluconate inhibited the planktonic growth of different bacterial species at sub-MICs. But they were able to induce biofilm development of the E. coli, Salmonella spp., S. aureus and Str. agalactiae strains. Bacterial resistance against chlorhexidine is increasing. Sub-MIC doses of chlorhexidine digluconate can stimulate the formation of biofilm strains.

Chlorhexidine Digluconate Effects on Planktonic Growth and Biofilm Formation in Some Field Isolates of Animal Bacterial Pathogens

PubMed Central

Ebrahimi, Azizollah; Hemati, Majid; Habibian Dehkordi, Saeed; Bahadoran, Shahab; Khoshnood, Sheida; Khubani, Shahin; Dokht Faraj, Mahdi; Hakimi Alni, Reza

2014-01-01

Background: To study chlorhexidine digluconate disinfectant effects on planktonic growth and biofilm formation in some bacterial field isolates from animals. Objectives: The current study investigated chlorhexidine digluconate effects on planktonic growth and biofilm formation in some field isolates of veterinary bacterial pathogens. Materials and Methods: Forty clinical isolates of Escherichia coli, Salmonella serotypes, Staphylococcus. aureus and Streptococcus agalactiae (10 isolates for each) were examined for chlorhexidine digluconate effects on biofilm formation and planktonic growth using microtiter plates. In all of the examined strains in the presence of chlorhexidine digluconate, biofilm development and planktonic growth were affected at the same concentrations of the disinfectant. Results: Chlorhexidine digluconate inhibited the planktonic growth of different bacterial species at sub-MICs. But they were able to induce biofilm development of the E. coli, Salmonella spp., S. aureus and Str. agalactiae strains. Conclusions: Bacterial resistance against chlorhexidine is increasing. Sub-MIC doses of chlorhexidine digluconate can stimulate the formation of biofilm strains. PMID:24872940

Federal and State Quarantine and Isolation Authority

DTIC Science & Technology

2006-08-16

agents that are naturally occurring or released during a terrorist attack, the isolation of infected persons, and the quarantine of certain cities or...http://www.cdc.gov/ncidod/dq/sars_facts/isolationquarantine.pdf]. 9 42 U.S.C. § 264(e) and 42 C.F.R. § 70.2. agent from infecting others.5 The... agents ,” which include “anthrax, ebola, plague, smallpox, tularemia, or other bacterial, fungal, rickettsial, or viral agent , biological toxin, or other

A study of bacterial pathogens and antibiotic susceptibility patterns in chronic suppurative otitis media.

PubMed

Mofatteh, M R; Shahabian Moghaddam, F; Yousefi, M; Namaei, M H

2018-01-01

To assess the frequency of bacterial agents in chronic suppurative otitis media and the antibiotic susceptibility patterns of isolates among patients. A total of 185 patients clinically diagnosed with chronic suppurative otitis media were interviewed and middle-ear effusion samples were collected using sterile swabs. All bacterial isolates were identified by conventional microbiological methods. Antibiotic susceptibility patterns of the isolates were determined by Kirby-Bauer disc diffusion. Staphylococci spp. (64.9 per cent) were the most prevalent bacteria isolated, followed by Klebsiella spp. (12.9 per cent) and Pseudomonas aeruginosa (10.3 per cent). The most effective antibiotic for treatment of bacterial chronic suppurative otitis media was ciprofloxacin. Statistical analysis showed no significant difference in bacterial infestations among chronic suppurative otitis media patients and the antimicrobial susceptibility patterns of the bacterial isolates based on gender and age (p > 0.05). Our findings highlight the importance of a continuous and periodic evaluation of the bacteriological profile and antibiotic susceptibility patterns in chronic suppurative otitis media patients for efficacious treatment of the infection.

[Susceptibilities of Escherichia coli, Salmonella and Staphylococcus aureus isolated from animals to ofloxacin and commonly used antimicrobial agents].

PubMed

Takahashi, I; Yoshida, T; Higashide, Y; Sakano, T

1990-01-01

to all the test drugs other than OFLX and OXA. These resistant isolates amounted to a total of 12 isolates (42.9%). 4. S. aureus (28 isolates) were highly susceptible to OFLX (MIC50 and MIC90 were both 0.78 micrograms/ml). Commonly used antimicrobial agents to which the isolates responded with high to relatively high susceptibilities (MIC50 0.10-6.25 micrograms/ml) were, in the increasing order of MIC50: DOXY, ABPC, tylosin, tiamulin, KM, OXA and CP. Drugs with moderate to low bacterial susceptibilities (MIC50 12.5-100 microns/ml) were SD, SDMX and SPCM. Isolates resistant to all the test drugs except OFLX and SDMX amounted to 3.6-50% of the 28 isolates examined and they totalled 20 isolates (71.4%).(ABSTRACT TRUNCATED AT 400 WORDS)

Proteolysis produced within biofilms of bacterial isolates from raw milk tankers.

PubMed

Teh, Koon Hoong; Flint, Steve; Palmer, Jon; Andrewes, Paul; Bremer, Phil; Lindsay, Denise

2012-06-15

In this study, six bacterial isolates that produced thermo-resistant enzymes isolated from the internal surfaces of raw milk tankers were evaluated for their ability to produce proteolysis within either single culture biofilms or co-culture biofilms. Biofilms were formed in an in vitro model system that simulated the upper internal surface of a raw milk tanker during a typical summer's day of milk collection in New Zealand. The bacterial isolates were further evaluated for their ability to form biofilms at 25, 30 and 37°C. Mutual and competitive effects were observed in some of the co-culture biofilms, with all isolates being able to form biofilms in either single culture or co-culture at the three temperatures. The proteolysis was also evaluated in both biofilms and corresponding planktonic cultures. The proteolysis per cell decreased as the temperature of incubation (20-37°C) increased. Furthermore, mutualistic interactions in terms of proteolysis were observed when cultures were grown as co-culture biofilms. This is the first study to show that proteolytic enzymes can be produced in biofilms on the internal surfaces of raw milk tankers. This has important implications for the cleaning and the temperature control of raw milk transport tankers. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigation of In vitro Mineral forming bacterial isolates from supragingival calculus.

PubMed

Baris, O; Demir, T; Gulluce, M

2017-12-01

Although it is known that bacterial mechanisms are involved in dental calculus formation, which is a predisposing factor in periodontal diseases, there have been few studies of such associations, and therefore, information available is limited. The purpose of this study was to isolate and identify aerobic bacteria responsible for direct calcification from supragingival calculus samples. The study was conducted using supragingival calculus samples from patients with periodontal disease, which was required as part of conventional treatment. Isolations were performed by sampling the supragingival calculus with buffer and inoculating the samples on media on which crystallization could be observed. The 16S recombinant DNA of the obtained pure cultures was then amplified and sequenced. A few bacterial species that have not previously been associated with mineralization or identified on bacterial plaque or calculus were detected. The bacteria that caused mineralization an aerobic environment are identified as Neisseria flava, Aggregatibacter segnis, Streptococcus tigurinus, and Morococcus cerebrosus. These findings proved that bacteria potentially play a role in the etiopathology of supragingival calculus. The association between the effects of the identified bacteria on periodontal diseases and calculus formation requires further studies.

Characterization of bacterial knot disease caused by Pseudomonas savastanoi pv. savastanoi on pomegranate (Punica granatum L.) trees: a new host of the pathogen.

PubMed

Bozkurt, I A; Soylu, S; Mirik, M; Ulubas Serce, C; Baysal, Ö

2014-11-01

This study aimed to isolate and identify the causal organism causing hyperplastic outgrowths (knots) on stems and branches of pomegranate trees in the Eastern Mediterranean region of Turkey. Bacterial colonies were isolated from young knots on plates containing selective nutrient media. Biochemical tests, fatty acid analysis and PCR were performed to identify possible causal disease agent. Representative isolates were identified as Pseudomonas.pv.savastanoi (Psv) using biochemical tests, fatty acid profiling and PCR. Following inoculation of pomegranate plants (cv. hicaz) with bacterial suspensions, 25 of 54 bacterial isolates caused typical knots at the site of inoculation. PCR analysis, using specific primer for Psv, generated a single amplicon from all isolates. The similarity of the sequence of Turkish pomegranate isolate was 99% similar to the corresponding gene sequences of Psv in the databases. Based on symptoms, biochemical, molecular, pathogenicity tests and sequence analyses, the disease agent of knots observed on the pomegranate trees is Psv. To the best of our knowledge, this research has revealed pomegranate as a natural host of Psv, which extends the list of host plant species affected by the pathogen in the world and Turkey. Pomegranate trees were affected by the disease with outgrowths (galls or knot) disease. Currently, there is no published study on disease agent(s) causing the galls or knots on pomegranate trees in worldwide. Bacterial colonies were isolated from young knots. The causal agent of the knot Pseudomonas savastanoi pv.savastanoi (Psv) was identified based on symptoms, biochemical, molecular methods, pathogenicity tests and sequence analysis. To the best of our knowledge, this is the first report of Psv on pomegranate as a natural host, which extends the growing list of plant species affected by this bacterium in the world and Turkey. © 2014 The Society for Applied Microbiology.

Larvicidal Activities of Indigenous Bacillus thuringiensis Isolates and Nematode Symbiotic Bacterial Toxins against the Mosquito Vector, Culex pipiens (Diptera: Culicidae).

PubMed

Ahmed, Ashraf M; Hussein, Hamdy I; El-Kersh, Talat A; Al-Sheikh, Yazeed A; Ayaad, Tahany H; El-Sadawy, Hanan A; Al-Mekhlafi, Fahd A; Ibrahim, Mohamed S; Al-Tamimi, Jameel; Nasr, Fahd A

2017-06-01

The incidence of mosquito-borne diseases and the resistance of mosquitoes to conventional pesticides have recently caused a panic to the authorities in the endemic countries. This study was conducted to identify native larvicidal biopesticides against Culex pipiens for utilization in the battle against mosquito-borne diseases. Larvicidal activities of new indigenous Bacillus thuringiensis isolates and crude toxin complexes (TCs) of two nematode bacterial-symbionts, Photorhabdus luminescens akhurstii (HRM1) and Ph. luminescens akhurstii (HS1) that tested against Cx. pipiens . B. thuringiensis isolates were recovered from different environmental samples in Saudi Arabia, and the entomopathogenic nematodes, Heterorhabditis indica (HRM1) and He. sp (HS1) were isolated from Egypt. Larvicidal activities (LC 50 and LC 95 ) of the potentially active B. thuringiensis strains or TCs were then evaluated at 24 and 48h post-treatment. Three B. thuringiensis isolates were almost as active as the reference B. thuringiensis israelensis (Bti-H14), and seven isolates were 1.6-5.4 times more toxic than Bti-H14. On the other hand, the TCs of the bacterial symbionts, HRM1 and HS1, showed promising larvicidal activities. HS1 showed LC 50 of 2.54 folds that of HRM1 at 24h post-treatment. Moreover, histopathological examinations of the HS1-treated larvae showed deformations in midgut epithelial cells at 24h post-treatment. Synergistic activity and molecular characterization of these potentially active biocontrol agents are currently being investigated. These results may lead to the identification of eco-friend mosquito larvicidal product(s) that could contribute to the battle against mosquito-borne diseases.

Larvicidal Activities of Indigenous Bacillus thuringiensis Isolates and Nematode Symbiotic Bacterial Toxins against the Mosquito Vector, Culex pipiens (Diptera: Culicidae)

PubMed Central

Ahmed, Ashraf M; Hussein, Hamdy I; El-Kersh, Talat A; Al-Sheikh, Yazeed A; Ayaad, Tahany H; El-Sadawy, Hanan A; Al-Mekhlafi, Fahd A; Ibrahim, Mohamed S; Al-Tamimi, Jameel; Nasr, Fahd A

2017-01-01

Background: The incidence of mosquito-borne diseases and the resistance of mosquitoes to conventional pesticides have recently caused a panic to the authorities in the endemic countries. This study was conducted to identify native larvicidal biopesticides against Culex pipiens for utilization in the battle against mosquito-borne diseases. Methods: Larvicidal activities of new indigenous Bacillus thuringiensis isolates and crude toxin complexes (TCs) of two nematode bacterial-symbionts, Photorhabdus luminescens akhurstii (HRM1) and Ph. luminescens akhurstii (HS1) that tested against Cx. pipiens. B. thuringiensis isolates were recovered from different environmental samples in Saudi Arabia, and the entomopathogenic nematodes, Heterorhabditis indica (HRM1) and He. sp (HS1) were isolated from Egypt. Larvicidal activities (LC50 and LC95) of the potentially active B. thuringiensis strains or TCs were then evaluated at 24 and 48h post-treatment. Results: Three B. thuringiensis isolates were almost as active as the reference B. thuringiensis israelensis (Bti-H14), and seven isolates were 1.6–5.4 times more toxic than Bti-H14. On the other hand, the TCs of the bacterial symbionts, HRM1 and HS1, showed promising larvicidal activities. HS1 showed LC50 of 2.54 folds that of HRM1 at 24h post-treatment. Moreover, histopathological examinations of the HS1-treated larvae showed deformations in midgut epithelial cells at 24h post-treatment. Conclusion: Synergistic activity and molecular characterization of these potentially active biocontrol agents are currently being investigated. These results may lead to the identification of eco-friend mosquito larvicidal product(s) that could contribute to the battle against mosquito-borne diseases. PMID:29062851

Diversity and Antibiograms of Bacterial Organisms Isolated from Samples of Household Drinking-water Consumed by HIV-positive Individuals in Rural Settings, South Africa

PubMed Central

Mashao, M.B.; Bessong, P.O.; NKgau, T.F.; Momba, M.N.B.; Obi, C.L.

2012-01-01

Diarrhoea is a hallmark of HIV infections in developing countries, and many diarrhoea-causing agents are often transmitted through water. The objective of the study was to determine the diversity and antibiotic susceptibility profiles of bacterial organisms isolated from samples of household drinking-water consumed by HIV-infected and AIDS patients. In the present study, household water stored for use by HIV-positive patients was tested for microbial quality, and isolated bacterial organisms were analyzed for their susceptibility profiles against 25 different antibiotics. The microbial quality of water was generally poor, and about 58% of water samples (n=270) were contaminated with faecal coliforms, with counts varying from 2 colony-forming unit (CFU)/100 mL to 2.4×104 CFU/100 mL. Values of total coliform counts ranged from 17 CFU/100 mL to 7.9×105/100 mL. In total, 37 different bacterial species were isolated, and the major isolates included Acinetobacter lwoffii (7.5%), Enterobacter cloacae (7.5%), Shigella spp. (14.2%), Yersinia enterocolitica (6.7%), and Pseudomonas spp. (16.3%). No Vibrio cholerae could be isolated; however, V. fluvialis was isolated from three water samples. The isolated organisms were highly resistant to cefazolin (83.5%), cefoxitin (69.2%), ampicillin (66.4%), and cefuroxime (66.2%). Intermediate resistance was observed against gentamicin (10.6%), cefepime (13.4%), ceftriaxone (27.6%), and cefotaxime (29.9%). Levofloxacin (0.7%), ceftazidime (2.2%), meropenem (3%), and ciprofloxacin (3.7%) were the most active antibiotics against all the microorganisms, with all recording less than 5% resistance. Multiple drug resistance was very common, and 78% of the organisms were resistant to three or more antibiotics. Education on treatment of household water is advised for HIV-positive patients, and measures should be taken to improve point-of-use water treatment as immunosuppressed individuals would be more susceptible to opportunistic infections

Diversity and antibiograms of bacterial organisms isolated from samples of household drinking-water consumed by HIV-positive individuals in rural settings, South Africa.

PubMed

Samie, A; Mashao, M B; Bessong, P O; NKgau, T F; Momba, M N B; Obi, C L

2012-09-01

Diarrhoea is a hallmark of HIV infections in developing countries, and many diarrhoea-causing agents are often transmitted through water. The objective of the study was to determine the diversity and antibiotic susceptibility profiles of bacterial organisms isolated from samples of household drinking-water consumed by HIV-infected and AIDS patients. In the present study, household water stored for use by HIV-positive patients was tested for microbial quality, and isolated bacterial organisms were analyzed for their susceptibility profiles against 25 different antibiotics. The microbial quality of water was generally poor, and about 58% of water samples (n=270) were contaminated with faecal coliforms, with counts varying from 2 colony-forming unit (CFU)/100 mL to 2.4x10⁴ CFU/100 mL. Values of total coliform counts ranged from 17 CFU/100 mL to 7.9x10⁵/100 mL. In total, 37 different bacterial species were isolated, and the major isolates included Acinetobacter lwoffii (7.5%), Enterobacter cloacae (7.5%), Shigella spp. (14.2%), Yersinia enterocolitica (6.7%), and Pseudomonas spp. (16.3%). No Vibrio cholerae could be isolated; however, V. fluvialis was isolated from three water samples. The isolated organisms were highly resistant to cefazolin (83.5%), cefoxitin (69.2%), ampicillin (66.4%), and cefuroxime (66.2%). Intermediate resistance was observed against gentamicin (10.6%), cefepime (13.4%), ceftriaxone (27.6%), and cefotaxime (29.9%). Levofloxacin (0.7%), ceftazidime (2.2%), meropenem (3%), and ciprofloxacin (3.7%) were the most active antibiotics against all the microorganisms, with all recording less than 5% resistance. Multiple drug resistance was very common, and 78% of the organisms were resistant to three or more antibiotics. Education on treatment of household water is advised for HIV-positive patients, and measures should be taken to improve point-of-use water treatment as immunosuppressed individuals would be more susceptible to opportunistic

A marine bacterial adhesion microplate test using the DAPI fluorescent dye: a new method to screen antifouling agents.

PubMed

Leroy, C; Delbarre-Ladrat, C; Ghillebaert, F; Rochet, M J; Compère, C; Combes, D

2007-04-01

To develop a method to screen antifouling agents against marine bacterial adhesion as a sensitive, rapid and quantitative microplate fluorescent test. Our experimental method is based on a natural biofilm formed by mono-incubation of the marine bacterium Pseudoalteromonas sp. D41 in sterile natural sea water in a 96-well polystyrene microplate. The 4'6-diamidino-2-phenylindole dye was used to quantify adhered bacteria in each well. The total measured fluorescence in the wells was correlated with the amount of bacteria showing a detection limit of one bacterium per 5 microm(2) and quantifying 2 x 10(7) to 2 x 10(8) bacteria adhered per cm(2). The antifouling properties of three commercial surface-active agents and chlorine were tested by this method in the prevention of adhesion and also in the detachment of already adhered bacteria. The marine bacterial adhesion inhibition rate depending on the agent concentration showed a sigmoid shaped dose-response curve. This test is well adapted for a rapid and quantitative first screening of antifouling agents directly in seawater in the early steps of marine biofilm formation. In contrast to the usual screenings of antifouling products which detect a bactericidal activity, this test is more appropriate to screen antifouling agents for bacterial adhesion removal or bacterial adhesion inhibition activities. This screening test focuses on the antifouling properties of the products, especially the initial steps of marine biofilm formation.

Nonspecific Bacterial Flora Isolated from the Body Surface and Inside Ixodes ricinus Ticks.

PubMed

Okła, Hubert; Sosnowska, Malwina; Jasik, Krzysztof P; Słodki, Jan; Wojtyczka, Robert D

2012-09-28

Ixodes ricinus and other representatives of the order Ixodida are vectors of typical pathogens: Borrelia burgdorferi sensu lato, Anaplasma phagocytophilium, Babesia spp., a tick-borne encephalitis virus, and other microorganisms which are important from a medical and veterinary point of view. The presented study focuses on the verification of nonspecific bacterial flora of I. ricinus. We analyzed ticks collected in a forest region in Silesia, an industrial district in Poland. Methods of classical microbiology and biochemical assays (API 20 NE test, API Staph test and MICRONAUT System) were used for isolation and identification of microorganisms living on the body surface of I. ricinus and inside ticks. The results show the presence of various bacteria on the surface and inside ticks' bodies. During the study, we isolated Acinetobacter lwoffi, Pseudomonas fluorescens, Aeromonas hydrophila, Achromobacter denitrificans, Alcaligenes faecalis, Stenotrophomonas maltophilia, Pseudomonas oryzihabitans, Micrococcus spp., Kocuria varians, Staphylococcus lentus, Kocuria kristinae, Streptococcus pneumoniae, Rhizobium radiobacter, Staphylococcus xylosus. Majority of the isolated species are non-pathogenic environmental microorganisms, but some of the isolated bacterial strains could cause severe infections.

Susceptibility of bacteria isolated from acute gastrointestinal infections to rifaximin and other antimicrobial agents in Mexico.

PubMed

Novoa-Farías, O; Frati-Munari, A C; Peredo, M A; Flores-Juárez, S; Novoa-García, O; Galicia-Tapia, J; Romero-Carpio, C E

2016-01-01

Bacterial resistance may hamper the antimicrobial management of acute gastroenteritis. Bacterial susceptibility to rifaximin, an antibiotic that achieves high fecal concentrations (up to 8,000μg/g), has not been evaluated in Mexico. To determine the susceptibility to rifaximin and other antimicrobial agents of enteropathogenic bacteria isolated from patients with acute gastroenteritis in Mexico. Bacterial strains were analyzed in stool samples from 1,000 patients with diagnosis of acute gastroenteritis. The susceptibility to rifaximin (RIF) was tested by microdilution (<100, <200, <400 and <800μg/ml) and susceptibility to chloramphenicol (CHL), trimethoprim-sulfamethoxazole (T-S), neomycin (NEO), furazolidone (FUR), fosfomycin (FOS), ampicillin (AMP) and ciprofloxacin (CIP) was tested by agar diffusion at the concentrations recommended by the Clinical & Laboratory Standards Institute and the American Society for Microbiology. Isolated bacteria were: enteropathogenic Escherichia coli (E. coli) (EPEC) 531, Shigella 120, non-Typhi Salmonella 117, Aeromonas spp. 80, enterotoxigenic E. coli (ETEC) 54, Yersinia enterocolitica 20, Campylobacter jejuni 20, Vibrio spp. 20, Plesiomonas shigelloides 20, and enterohemorrhagic E. coli (EHEC 0:157) 18. The overall cumulative susceptibility to RIF at <100, <200, <400, and <800μg/ml was 70.6, 90.8, 99.3, and 100%, respectively. The overall susceptibility to each antibiotic was: AMP 32.2%, T-S 53.6%, NEO 54.1%, FUR 64.7%, CIP 67.3%, CLO 73%, and FOS 81.3%. The susceptibility to RIF <400 and RIF <800μg/ml was significantly greater than with the other antibiotics (p<0.001). Resistance of enteropathogenic bacteria to various antibiotics used in gastrointestinal infections is high. Rifaximin was active against 99-100% of these enteropathogens at reachable concentrations in the intestine with the recommended dose. Copyright © 2015 Asociación Mexicana de Gastroenterología. Published by Masson Doyma México S.A. All rights reserved.

Monitoring of oil pollution at Gemsa Bay and bioremediation capacity of bacterial isolates with biosurfactants and nanoparticles.

PubMed

El-Sheshtawy, H S; Khalil, N M; Ahmed, W; Abdallah, R I

2014-10-15

Fifteen crude oil-degrading bacterial isolates were isolated from an oil-polluted area in Gemsa Bay, Red Sea, Egypt. Two bacterial species showed the highest growth rate on crude oil hydrocarbons. From an analysis of 16S rRNA sequences, these isolates were identified as Pseudomonas xanthomarina KMM 1447 and Pseudomonas stutzeri ATCC 17588. Gas Chromatographic (GC) analysis of the crude oil remaining in the culture medium after one week at 30°C showed that the optimum biodegradation of crude petroleum oil was demonstrated at 50% in medium containing biosurfactant with two types of nanoparticles separately and two bacterial species. The complete degradation of some different members of polyaromatics and the percentage biodegradation of other polyaromatics increased in microcosm containing two different types of nanoparticles with biosurfactant after 7 days. In conclusion, these bacterial strains may be useful for the bioremediation process in the Gemsa Bay, Red Sea decreasing oil pollution in this marine ecosystem. Copyright © 2014 Elsevier Ltd. All rights reserved.

Isolation of an agent causing bilirubinemia and jaundice in raccoons

USGS Publications Warehouse

Kilham, L.; Herman, C.M.

1954-01-01

An infectious agent, which appears to be a virus (RJV) has been isolated from the liver of a wild raccoon which has led to a highly fatal type of disease characterized by conjunctivitis and an elevated serum bilirubin frequently accompanied by jaundice on inoculation of raccoons. Ferrets also appear to be susceptible to infections with this agent.

Antibacterial activity of natural spices on multiple drug resistant Escherichia coli isolated from drinking water, Bangladesh

PubMed Central

2011-01-01

Background Spices traditionally have been used as coloring agents, flavoring agents, preservatives, food additives and medicine in Bangladesh. The present work aimed to find out the antimicrobial activity of natural spices on multi-drug resistant Escherichia coli isolates. Methods Anti-bacterial potentials of six crude plant extracts (Allium sativum, Zingiber officinale, Allium cepa, Coriandrum sativum, Piper nigrum and Citrus aurantifolia) were tested against five Escherichia coli isolated from potable water sources at kushtia, Bangladesh. Results All the bacterial isolates were susceptible to undiluted lime-juice. None of them were found to be susceptible against the aqueous extracts of garlic, onion, coriander, pepper and ginger alone. However, all the isolates were susceptible when subjected to 1:1:1 aqueous extract of lime, garlic and ginger. The highest inhibition zone was observed with lime (11 mm). Conclusion Natural spices might have anti-bacterial activity against enteric pathogens and could be used for prevention of diarrheal diseases. Further evaluation is necessary. PMID:21406097

Antibacterial activity of natural spices on multiple drug resistant Escherichia coli isolated from drinking water, Bangladesh.

PubMed

Rahman, Shahedur; Parvez, Anowar Khasru; Islam, Rezuanul; Khan, Mahboob Hossain

2011-03-15

Spices traditionally have been used as coloring agents, flavoring agents, preservatives, food additives and medicine in Bangladesh. The present work aimed to find out the antimicrobial activity of natural spices on multi-drug resistant Escherichia coli isolates. Anti-bacterial potentials of six crude plant extracts (Allium sativum, Zingiber officinale, Allium cepa, Coriandrum sativum, Piper nigrum and Citrus aurantifolia) were tested against five Escherichia coli isolated from potable water sources at kushtia, Bangladesh. All the bacterial isolates were susceptible to undiluted lime-juice. None of them were found to be susceptible against the aqueous extracts of garlic, onion, coriander, pepper and ginger alone. However, all the isolates were susceptible when subjected to 1:1:1 aqueous extract of lime, garlic and ginger. The highest inhibition zone was observed with lime (11 mm). Natural spices might have anti-bacterial activity against enteric pathogens and could be used for prevention of diarrheal diseases. Further evaluation is necessary.

Assessment of bacterial diversity during composting of agricultural byproducts

PubMed Central

2013-01-01

Background Composting is microbial decomposition of biodegradable materials and it is governed by physicochemical, physiological and microbiological factors. The importance of microbial communities (bacteria, actinomycetes and fungi) during composting is well established. However, the microbial diversity during composting may vary with the variety of composting materials and nutrient supplements. Therefore, it is necessary to study the diversity of microorganisms during composting of different agricultural byproducts like wheat bran, rice bran, rice husk, along with grass clippings and bulking agents. Here it has been attempted to assess the diversity of culturable bacteria during composting of agricultural byproducts. Results The culturable bacterial diversity was assessed during the process by isolating the most prominent bacteria. Bacterial population was found to be maximum during the mesophilic phase, but decreased during the thermophilic phase and declined further in the cooling and maturation phase of composting. The bacterial population ranged from 105 to 109 cfu g-1 compost. The predominant bacteria were characterized biochemically, followed by 16S rRNA gene sequencing. The isolated strains, both Gram-positive and Gram-negative groups belonged to the order Burkholderiales, Enterobacteriales, Actinobacteriales and Bacillales, which includes genera e.g. Staphylococcus, Serratia, Klebsiella, Enterobacter, Terribacillus, Lysinibacillus Kocuria, Microbacterium, Acidovorax and Comamonas. Genera like Kocuria, Microbacterium, Acidovorax, Comamonas and some new species of Bacillus were also identified for the first time from the compost made from agricultural byproducts. Conclusion The use of appropriate nitrogen amendments and bulking agents in composting resulted in good quality compost. The culture based strategy enabled us to isolate some novel bacterial isolates like Kocuria, Microbacterium, Acidovorax and Comamonas first time from agro-byproducts compost

The antimicrobial activity of honey against common equine wound bacterial isolates.

PubMed

Carnwath, R; Graham, E M; Reynolds, K; Pollock, P J

2014-01-01

Delayed healing associated with distal limb wounds is a particular problem in equine clinical practice. Recent studies in human beings and other species have demonstrated the beneficial wound healing properties of honey, and medical grade honey dressings are available commercially in equine practice. Equine clinicians are reported to source other non-medical grade honeys for the same purpose. This study aimed to assess the antimicrobial activity of a number of honey types against common equine wound bacterial pathogens. Twenty-nine honey products were sourced, including gamma-irradiated and non-irradiated commercial medical grade honeys, supermarket honeys, and honeys from local beekeepers. To exclude contaminated honeys from the project, all honeys were cultured aerobically for evidence of bacterial contamination. Aerobic bacteria or fungi were recovered from 18 products. The antimicrobial activity of the remaining 11 products was assessed against 10 wound bacteria, recovered from the wounds of horses, including methicillin resistant Staphylococcus aureus and Pseudomonas aeruginosa. Eight products were effective against all 10 bacterial isolates at concentrations varying from <2% to 16% (v/v). Overall, the Scottish Heather Honey was the best performing product, and inhibited the growth of all 10 bacterial isolates at concentrations ranging from <2% to 6% (v/v). Although Manuka has been the most studied honey to date, other sources may have valuable antimicrobial properties. Since some honeys were found to be contaminated with aerobic bacteria or fungi, non-sterile honeys may not be suitable for wound treatment. Further assessment of gamma-irradiated honeys from the best performing honeys would be useful. Copyright © 2013 Elsevier Ltd. All rights reserved.

Evaluation of isolation methods for bacterial RNA quantitation in Dickeya dadantii

USDA-ARS?s Scientific Manuscript database

Dickeya dadantii is a difficult source for RNA of a sufficient quality for real-time qRT-PCR analysis of gene expression. Three RNA isolation methods were evaluated for their ability to produce high-quality RNA from this bacterium. Bacterial lysis with Trizol using standard protocols consistently ga...

Label-free isolation and deposition of single bacterial cells from heterogeneous samples for clonal culturing

NASA Astrophysics Data System (ADS)

Riba, J.; Gleichmann, T.; Zimmermann, S.; Zengerle, R.; Koltay, P.

2016-09-01

The isolation and analysis of single prokaryotic cells down to 1 μm and less in size poses a special challenge and requires micro-engineered devices to handle volumes in the picoliter to nanoliter range. Here, an advanced Single-Cell Printer (SCP) was applied for automated and label-free isolation and deposition of bacterial cells encapsulated in 35 pl droplets by inkjet-like printing. To achieve this, dispenser chips to generate micro droplets have been fabricated with nozzles 20 μm in size. Further, the magnification of the optical system used for cell detection was increased. Redesign of the optical path allows for collision-free addressing of any flat substrate since no compartment protrudes below the nozzle of the dispenser chip anymore. The improved system allows for deterministic isolation of individual bacterial cells. A single-cell printing efficiency of 93% was obtained as shown by printing fluorescent labeled E. coli. A 96-well plate filled with growth medium is inoculated with single bacteria cells on average within about 8 min. Finally, individual bacterial cells from a heterogeneous sample of E. coli and E. faecalis were isolated for clonal culturing directly on agar plates in user-defined array geometry.

Isolation of bacterial metabolites as natural inducers for larval settlement in the marine polychaete Hydroides elegans (Haswell).

PubMed

Harder, Tilmann; Lau, Stanley Chun Kwan; Dahms, Hans-Uwe; Qian, Pei-Yuan

2002-10-01

The bacterial component of marine biofilms plays an important role in the induction of larval settlement in the polychaete Hydroides elegans. In this study, we provide experimental evidence that bacterial metabolites comprise the chemical signal for larval settlement. Bacteria were isolated from biofilms, purified and cultured according to standard procedures. Bacterial metabolites were isolated from spent culture broth by chloroform extraction as well as by closed-loop stripping and adsorption of volatile components on surface-modified silica gel. A pronounced biological activity was exclusively observed when concentrated metabolites were adsorbed on activated charcoal. Larvae did not respond to waterbome metabolites when prevented from contacting the bacterial film surface. These results indicate that an association of the chemical signal with a sorbent-like substratum may be an essential cofactor for the expression of biological activity. The functional role of bacterial exopolymers as an adsorptive matrix for larval settlement signals is discussed.

An in vitro biofilm model to examine the effect of antibiotic ointments on biofilms produced by burn wound bacterial isolates.

PubMed

Hammond, Adrienne A; Miller, Kyle G; Kruczek, Cassandra J; Dertien, Janet; Colmer-Hamood, Jane A; Griswold, John A; Horswill, Alexander R; Hamood, Abdul N

2011-03-01

Topical treatment of burn wounds is essential as reduced blood supply in the burned tissues restricts the effect of systemic antibiotics. On the burn surface, microorganisms exist within a complex structure termed a biofilm, which enhances bacterial resistance to antimicrobial agents significantly. Since bacteria differ in their ability to develop biofilms, the susceptibility of these biofilms to topically applied antibiotics varies, making it essential to identify which topical antibiotics efficiently disrupt or prevent biofilms produced by these pathogens. Yet, a simple in vitro assay to compare the susceptibility of biofilms produced by burn wound isolates to different topical antibiotics has not been reported. Biofilms were developed by inoculating cellulose disks on agar plates with burn wound isolates and incubating for 24h. The biofilms were then covered for 24h with untreated gauze or gauze coated with antibiotic ointment and remaining microorganisms were quantified and visualized microscopically. Mupirocin and triple antibiotic ointments significantly reduced biofilms produced by the Staphylococcus aureus and Pseudomonas aeruginosa burn wound isolates tested, as did gentamicin ointment, with the exception of one P. aeruginosa clinical isolate. The described assay is a practical and reproducible approach to identify topical antibiotics most effective in eliminating biofilms produced by burn wound isolates. Copyright © 2010 Elsevier Ltd and ISBI. All rights reserved.

Potency of Bacillus thuringiensis isolates from bareng Tenes-Malang City as a biological control agent for suppressing third instar of Aedes aegypti larvae

NASA Astrophysics Data System (ADS)

Lutfiana, Nihayatul; Gama, Zulfaidah Penata

2017-11-01

Dengue is a mosquito-borne viral disease that is transmitted by the female Aedes species. The number of dengue fever cases has increased in many geographic regions including Indonesia and one of them occurred in Bareng Tenes, Malang City, East Java Province. The objective of this research was to identify the potency of B. thuringeinsis isolates from Bareng Tenes, Malang, as the biological agent to control third instar Ae. aegypti larvae and to identify the potential B. thuringiensis isolates based on 16S rDNA sequence. B. thuringiensis was isolated from water and soil from 12 sites in the Bareng Tenes area. Bacterial isolation was performed using B. thuringiensis selective media. Several isolates had similar phenotypic characters with B. thuringiensis used to toxicity test against third instar Ae. aegypti larvae. The LC50-96h value was determined using probit regression. The most effective isolate was identified based on the 16S rDNA sequence, then aligned to the reference isolate using the BLAST program. A phylogeny tree was constructed using the Maximum Likelihood method. This study showed that among 22 isolates of B. thuringiensis, only BA02b, BS04a, and BA03a isolates have similar phenotypic characters with B. thuringiensis. Based on the toxicity test of B. thuringiensis against the third instar of Ae. aegypti larvae, it was indicated that BA02b and BA03a isolates were the potential agents to control Ae. aegypti larvae. BA02b isolate was the most effective B. thuringiensis (LC50-96h = 2,75 x 107 cell/mL). Based on 16S rDNA sequence, BA02b was identified as Bacillus thuringiensis var. Israelensis BGSC4Q2 (99 % similarities).

Frequency and antimicrobial susceptibility of aerobic bacterial vaginal isolates.

PubMed

Tariq, Nabia; Jaffery, Tara; Ayub, Rukhsana; Alam, Ali Yawar; Javid, Mahmud Haider; Shafique, Shamsa

2006-03-01

To determine the frequency and antimicrobial susceptibility of aerobic bacterial isolates from high vaginal swab cultures. Cross-sectional survey. Shifa International Hospital, Islamabad, from January 2003 to February 2004. The subjects included 136 symptomatic women attending Obstetrics and Gynecology Out-Patient Department. A proforma was filled to document the demographic details, presenting complaint and examination findings. High vaginal swabs were taken for gram staining, culture and antimicrobial sensitivity testing using standard microbiologic techniques. Normal flora was isolated in 30% of the cases, followed by Candida spp. (21.3%), Enterococcus spp. (14.7%), E.coli (10.2%), Beta hemolytic Streptococcus spp. (7.3%), Staphylococcus spp. (4.4%), Enterobacter spp. (4.4%), while Streptococcus pyogenes, Staphylococcus epidermidis and Klebsiella spp. were isolated 1.5% each. Enterococcus, Staphylococcus and Streptococcus were mostly sensitive to penicillin and amoxicillin while E.coli and Klebsiella were sensitive to (piperacillin-Tazobactum, Imipenem and vancomycin. Enterococci species showed significant resistance to aminoglycoside antibiotics (68.8% to 81.3%) resistance to vancomycin was 5%. Thirty percent of symptomatic patients had normal flora on culture. Candida spp was the most frequent pathogen isolated. Co-amoxiclav should be used as empiric therapy until culture-sensitivity report is available.

Bacterial Sepsis in Patients with Visceral Leishmaniasis in Northwest Ethiopia

PubMed Central

Takele, Yegnasew; Woldeyohannes, Desalegn; Tiruneh, Moges; Mohammed, Rezika; Lynen, Lutgarde; van Griensven, Johan

2014-01-01

Background and Objectives. Visceral leishmaniasis (VL) is one of the neglected diseases affecting the poorest segment of world populations. Sepsis is one of the predictors for death of patients with VL. This study aimed to assess the prevalence and factors associated with bacterial sepsis, causative agents, and their antimicrobial susceptibility patterns among patients with VL. Methods. A cross-sectional study was conducted among parasitologically confirmed VL patients suspected of sepsis admitted to the University of Gondar Hospital, Northwest Ethiopia, from February 2012 to May 2012. Blood cultures and other clinical samples were collected and cultured following the standard procedures. Results. Among 83 sepsis suspected VL patients 16 (19.3%) had culture confirmed bacterial sepsis. The most frequently isolated organism was Staphylococcus aureus (68.8%; 11/16), including two methicillin-resistant isolates (MRSA). Patients with focal bacterial infection were more likely to have bacterial sepsis (P < 0.001). Conclusions. The prevalence of culture confirmed bacterial sepsis was high, predominantly due to S. aureus. Concurrent focal bacterial infection was associated with bacterial sepsis, suggesting that focal infections could serve as sources for bacterial sepsis among VL patients. Careful clinical evaluation for focal infections and prompt initiation of empiric antibiotic treatment appears warranted in VL patients. PMID:24895569

Urinary tract infection in pregnant population, which empirical antimicrobial agent should be specified in each of the three trimesters?

PubMed

Unlu, Bekir Serdar; Yildiz, Yunus; Keles, Ibrahim; Kaba, Metin; Kara, Halil; Tasin, Cuma; Erkilinc, Selcuk; Yildirim, Gulcin

2014-05-01

We aimed to investigate the bacterial profile and the adequacy of antimicrobial treatment in pregnant women with urinary tract infection. This retrospective observational study was conducted with 753 pregnant women who needed hospitalization because of UTI in each of the three trimesters. Midstream urine culture and antimicrobial susceptibility tests were evaluated. E. Coli was the most frequently isolated bacterial agent (82.2%), followed by Klebsiella spp. (11.2%). In each of the three trimesters, E. Coli remained the most frequently isolated bacterium (86%, 82.2%, 79.5%, respectively), followed by Klebsiella spp. (9%, 11.6%, 12.2%, respectively). Enterococcus spp. were isolated as a third microbial agent, with 43 patients (5.7%) in the three trimesters. The bacteria were found to be highly sensitive to fosfomycin, with 98-99% sensitivity for E.Coli and 88-89% for Klebsiella spp. and for Enterococcus spp. 93-100% nitrofurantoin sensitivity for each of the three trimesters. We demonstrated that E. Coli and Klebsiella spp. are the most common bacterial agents isolated from urine culture of pregnant women with UTI in each of the three trimesters. We consider fosfomycin to be the most adequate first-line treatment regimen due to high sensitivity to the drug, ease of use and safety for use in pregnancy

Isolation and identification of bacterial populations of zoonotic importance from captive non-venomous snakes in Malaysia.

PubMed

Abba, Yusuf; Ilyasu, Yusuf Maina; Noordin, Mustapha Mohamed

2017-07-01

Captivity of non-venomous snakes such as python and boa are common in zoos, aquariums and as pets in households. Poor captivity conditions expose these reptiles to numerous pathogens which may result in disease conditions. The purpose of this study was to investigate the common bacteria isolated from necropsied captive snakes in Malaysia over a five year period. A total of 27 snake carcasses presented for necropsy at the Universiti Putra Malaysia (UPM) were used in this survey. Samples were aseptically obtained at necropsy from different organs/tissues (lung, liver, heart, kindey, oesophagus, lymph node, stomach, spinal cord, spleen, intestine) and cultured onto 5% blood and McConkey agar, respectively. Gram staining, morphological evaluation and biochemical test such as oxidase, catalase and coagulase were used to tentatively identify the presumptive bacterial isolates. Pythons had the highest number of cases (81.3%) followed by anaconda (14.8%) and boa (3.7%). Mixed infection accounted for 81.5% in all snakes and was highest in pythons (63%). However, single infection was only observed in pythons (18.5%). A total of 82.7%, 95.4% and 100% of the bacterial isolates from python, anaconda and boa, respectively were gram negative. Aeromonas spp was the most frequently isolated bacteria in pythons and anaconda with incidences of 25 (18%) and 8 (36.6%) with no difference (p > 0.05) in incidence, respectively, while Salmonella spp was the most frequently isolated in boa and significantly higher (p < 0.05) than in python and anaconda. Bacteria species were most frequently isolated from the kidney of pythons 35 (25.2%), intestines of anacondas 11 (50%) and stomach of boa 3 (30%). This study showed that captive pythons harbored more bacterial species than anaconda or boa. Most of the bacterial species isolated from these snakes have public health importance and have been incriminated in human infections worldwide. Copyright © 2017 Elsevier Ltd. All rights reserved.

Elucidating Duramycin's Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope.

PubMed

Hasim, Sahar; Allison, David P; Mendez, Berlin; Farmer, Abigail T; Pelletier, Dale A; Retterer, Scott T; Campagna, Shawn R; Reynolds, Todd B; Doktycz, Mitchel J

2018-01-01

The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus -derived bacterial isolates to determine species selectivity. Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE) in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin's mode of action and a better understanding of its selectivity.

Bacterial Coaggregation Among the Most Commonly Isolated Bacteria From Contact Lens Cases.

PubMed

Datta, Ananya; Stapleton, Fiona; Willcox, Mark D P

2017-01-01

To examine the coaggregation and cohesion between the commonly isolated bacteria from contact lens cases. Four or five strains each of commonly isolated bacteria from contact lens cases, Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, and Serratia marcescens, were grown, washed, mixed in equal proportions, and allowed to coaggregate for 24 hours. Lactose (0.06 M), sucrose (0.06 M), and pronase (2 mg/mL; 2 hours, 37°C) were used to inhibit coaggregation. Oral bacterial isolates of Actinomyces naeslundii and Streptococcus sanguinis were used as a positive control for coaggregation. Cohesion was performed with the ocular bacteria that demonstrated the highest level of coaggregation. Production of growth-inhibitory substances was measured by growing strains together on agar plates. The oral bacterial pair showed >80% coaggregation. Coaggregation occurred between ocular strains of S. aureus (2/5) or S. epidermidis (2/5) with P. aeruginosa strains (3/5); 42% to 62%. There was only slight coaggregation between staphylococci and S. marcescens. Staphylococcus aureus coaggregated with S. epidermidis. Lactose or sucrose treatment of S. aureus but pronase treatment of P. aeruginosa reversed the coaggregation. There was no cohesion between the ocular isolates. P. aeruginosa was able to stop growth of S. aureus but not vice versa. This study demonstrated for the first time that ocular isolates of P. aeruginosa and S. aureus could coaggregate, probably through lectin-carbohydrate interactions. However, this may not be related to biofilm formation in contact lens cases, as there was no evidence that the coaggregation was associated with cohesion between the strains.

Diversity of bacterial isolates from commercial and homemade composts.

PubMed

Vaz-Moreira, Ivone; Silva, Maria E; Manaia, Célia M; Nunes, Olga C

2008-05-01

The diversity of heterotrophic bacterial isolates of three commercial and two homemade composts was studied. The commercial composts were produced from poultry litter (PC), sewage sludge (SC), municipal solid waste (MC), and homemade composts (thermal compost [DC] and vermicompost [VC]) from food wastes. The taxonomic and physiological diversity of the heterotrophic culturable bacteria was assessed using phenotypic and genotypic characterization and the analysis of the partial 16S rRNA gene sequence. Composts DC and SC presented the higher genotypic diversity, as could be inferred from the number of distinct genotypic patterns observed, 28 and 21, respectively. Gram-positive bacteria, mainly Firmicutes, were predominant in all the composts. Some organisms related with taxa rarely reported in composts, as Rhodanobacter spathiphylli, Moraxella osloensis, Lysobacter, Corynebacterium, Pigmentiphaga kullae, and new taxa were also isolated. The highest relative proportion of isolates able to degrade starch was found in compost SC (> 70%), to degrade gelatine in compost DC (> 70%), to degrade Tween 80 in compost PC (> 90%), and to degrade poly-epsilon-caprolactones in compost DC (> 80%). Compost MC presented the lowest relative proportions of isolates able to degrade starch (< 25%), gelatine (< 20%), and poly-epsilon-caprolactone (< 40%). When compared with the others, the homemade composts presented higher relative proportions of Gram-positive isolates able to inhibit the target organisms Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, or Pseudomonas aeruginosa. In compost MC, none of the Gram-positive isolates was able to inhibit those targets.

Novel bacterial consortia isolated from plastic garbage processing areas demonstrated enhanced degradation for low density polyethylene.

PubMed

Skariyachan, Sinosh; Manjunatha, Vishal; Sultana, Subiya; Jois, Chandana; Bai, Vidya; Vasist, Kiran S

2016-09-01

This study aimed to formulate novel microbial consortia isolated from plastic garbage processing areas and thereby devise an eco-friendly approach for enhanced degradation of low-density polyethylene (LDPE). The LDPE degrading bacteria were screened and microbiologically characterized. The best isolates were formulated as bacterial consortia, and degradation efficiency was compared with the consortia formulated using known isolates obtained from the Microbial Culture Collection Centre (MTCC). The degradation products were analyzed by FTIR, GC-FID, tensile strength, and SEM. The bacterial consortia were characterized by 16S ribosomal DNA (rDNA) sequencing. The formulated bacterial consortia demonstrated 81 ± 4 and 38 ± 3 % of weight reduction for LDPE strips and LDPE pellets, respectively, over a period of 120 days. However, the consortia formulated by MTCC strains demonstrated 49 ± 4 and 20 ± 2 % of weight reduction for LDPE strips and pellets, respectively, for the same period. Furthermore, the three isolates in its individual application exhibited 70 ± 4, 68 ± 4, and 64 ± 4 % weight reduction for LDPE strips and 21 ± 2, 28 ± 2, 24 ± 2 % weight reduction for LDPE pellets over a period of 120 days (p < 0.05). The end product analysis showed structural changes and formation of bacterial film on degraded LDPE strips. The 16S rDNA characterization of bacterial consortia revealed that these organisms were novel strains and designated as Enterobacter sp. bengaluru-btdsce01, Enterobacter sp. bengaluru-btdsce02, and Pantoea sp. bengaluru-btdsce03. The current study thus suggests that industrial scale-up of these microbial consortia probably provides better insights for waste management of LDPE and similar types of plastic garbage.

Mass mortality in ornamental fish, Cyprinus carpio koi caused by a bacterial pathogen, Proteus hauseri.

PubMed

Kumar, Raj; Swaminathan, T Raja; Kumar, Rahul G; Dharmaratnam, Arathi; Basheer, V S; Jena, J K

2015-09-01

Moribund koi carp, Cyprinus carpio koi, from a farm with 50% cumulative mortality were sampled with the aim of isolating and detecting the causative agent. Three bacterial species viz., Citrobacter freundii (NSCF-1), Klebsiella pneumoniae (NSKP-1) and Proteus hauseri [genomospecies 3 of Proteus vulgaris Bio group 3] (NSPH-1) were isolated, identified and characterized on the basis of biochemical tests and sequencing of the 16S rDNA gene using universal bacterial primers. Challenge experiments with these isolates using healthy koi carp showed that P. hauseri induced identical clinical and pathological states within 3 d of intramuscular injection. The results suggest P. hauseri (NSPH-1) was the causative agent. In phylogenetic analysis, strain NSPH-1 formed a distinct cluster with other P. hauseri reference strains with ≥99% sequence similarity. P. hauseri isolates were found sensitive to Ampicillin, Cefalexin, Ciprofloxacin and Cefixime and resistant to Gentamycin, Oxytetracycline, Chloramphenicol, and Kanamycin. The affected fish recovered from the infection after ciprofloxacin treatment. Copyright © 2015 Elsevier B.V. All rights reserved.

Lytic agents, cell permeability, and monolayer penetrability.

PubMed

Salton, M R

1968-07-01

Cell lysis induced by lytic agents is the terminal phase of a series of events leading to membrane disorganization and breadkdown with the release of cellular macromolecules. Permeability changes following exposure to lytic systems may range from selective effects on ion fluxes to gross membrane damage and cell leakage. Lysis can be conceived as an interfacial phenomenon, and the action of surface-active agents on erythrocytes has provided a model in which to investigate relationships between hemolysis and chemical structure, ionic charge, surface tension lowering, and ability to penetrate monolayers of membrane lipid components. Evidence suggests that lysis follows the attainment of surface pressures exceeding a "critical collapse" level and could involve membrane cholesterol or phospholipid. Similarities of chemical composition of membranes from various cell types could account for lytic responses observed on interaction with surface-active agents. Cell membranes usually contain about 20-30 % lipid and 50-75 % protein. One or two major phospholipids are present in all cell membranes, but sterols are not detectable in bacterial membranes other than those of the Mycoplasma group. The rigid cell wall in bacteria has an important bearing on their response to treatment with lytic agents. Removal of the wall renders the protoplast membrane sensitive to rapid lysis with surfactants. Isolated membranes of erythrocytes and bacteria are rapidly dissociated by surface-active agents. Products of dissociation of bacterial membranes have uniform behavior in the ultracentrifuge (sedimentation coefficients 2-3S). Dissociation of membrane proteins from lipids and the isolation and characterization of these proteins will provide a basis for investigating the specificity of interaction of lytic agents with biomembranes.

Inactivation of bacterial biothreat agents in water, a review.

PubMed

Rose, L J; Rice, E W

2014-12-01

Water supplies and water distribution systems have been identified as potential targets for contamination by bacterial biothreat agents. Since the 2001 Bacillus anthracis bioterrorist attacks, additional efforts have been aimed at research to characterize biothreat organisms in regards to their susceptibility to disinfectants and technologies currently in use for potable water. Here, we present a review of research relevant to disinfection of bacteria with the potential to pose a severe threat to public health and safety, and their potential surrogates. The efficacy of chlorine, monochloramine, chlorine dioxide, and ultraviolet light to inactivate each organism in suspension is described. The complexities of disinfection under varying water conditions and when the organisms are associated with biofilms in distribution systems are discussed.

Antibiotic Susceptibility Patterns of Bacterial Isolates from Pus Samples in a Tertiary Care Hospital of Punjab, India

PubMed Central

Trojan, Rugira; Razdan, Lovely

2016-01-01

We determined the prevalence and antibiotic susceptibilities patterns of bacterial isolates from pus samples collected from patients in a tertiary care hospital of Punjab, India. E. coli was the most prevalent pathogen (51.2%) followed by Staphylococcus aureus (21%), Klebsiella pneumoniae (11.6%), Pseudomonas aeruginosa (5.8%), Citrobacter spp. (3.5%), Acinetobacter baumannii (2.3%), Proteus mirabilis (2.3%), and Streptococcus spp. (2.3%). E. coli, K. pneumoniae, A. baumannii, and Citrobacter isolates were resistant to multiple antibiotics including higher generation cephalosporins. S. aureus and Streptococcus isolates were sensitive to cloxacillin and vancomycin. However, P. aeruginosa, P. mirabilis, and Streptococcus isolates were found to be less resistant to the spectrum of antibiotics tested. Overall, our findings indicate the prevalence of resistance to different classes of antibiotics in bacterial isolates from pus infections and hence highlight the need for effective surveillance, regulator reporting, and antibiogram-guided antibiotic prescription. PMID:27872643

Antibiotic Susceptibility Patterns of Bacterial Isolates from Pus Samples in a Tertiary Care Hospital of Punjab, India.

PubMed

Trojan, Rugira; Razdan, Lovely; Singh, Nasib

2016-01-01

We determined the prevalence and antibiotic susceptibilities patterns of bacterial isolates from pus samples collected from patients in a tertiary care hospital of Punjab, India. E. coli was the most prevalent pathogen (51.2%) followed by Staphylococcus aureus (21%), Klebsiella pneumoniae (11.6%), Pseudomonas aeruginosa (5.8%), Citrobacte r spp. (3.5%), Acinetobacter baumannii (2.3%), Proteus mirabilis (2.3%), and Streptococcus spp. (2.3%). E. coli , K. pneumoniae , A. baumannii , and Citrobacter isolates were resistant to multiple antibiotics including higher generation cephalosporins. S. aureus and Streptococcus isolates were sensitive to cloxacillin and vancomycin. However, P. aeruginosa , P. mirabilis , and Streptococcus isolates were found to be less resistant to the spectrum of antibiotics tested. Overall, our findings indicate the prevalence of resistance to different classes of antibiotics in bacterial isolates from pus infections and hence highlight the need for effective surveillance, regulator reporting, and antibiogram-guided antibiotic prescription.

Microbiological and molecular identification of bacterial species isolated from nasal and oropharyngeal mucosa of fuel workers in Riyadh, Saudi Arabia.

PubMed

AlWakeel, Suaad S

2017-09-01

This study aimed to determine the bacterial species colonizing the nasal and oropharyngeal mucosa of fuel workers in Central Riyadh, Saudi Arabia on a microbiological and molecular level. Throat and nasal swab samples were obtained from 29 fuel station attendants in the period of time extending from March to May 2014 in Riyadh, Saudi Arabia. Microbiological identification techniques were utilized to identify the bacterial species isolated. Antibiotic sensitivity was assessed for each of the bacterial isolates. Molecular identification techniques based on PCR analysis of specific genomic sequences was conducted and was the basis on which phylogeny representation was done for 10 randomly selected samples of the isolates. Blood was drawn and a complete blood count was conducted to note the hematological indices for each of the study participants. Nineteen bacterial species were isolated from both the nasal cavity and the oropharynx including Streptococcus thoraltensis , alpha-hemolytic streptococci, Staphylococcus hominis , coagulase-negative staphylococci, Leuconostoc mesenteroides , Erysipelothrix rhusiopathiae and several others. We found 100% sensitivity of the isolates to ciprofloxacin, cefuroxime and gentamicin. Whereas cefotaxime and azithromycin posted sensitivities of 85.7% and 91.4%, respectively. Low sensitivities (<60% sensitivity) to the antibiotics ampicillin, erythromycin, clarithromycin and norfloxacin were observed. Ninety-seven percent similarity to the microbial bank species was noted when the isolates were compared to it. Most hematological indices recorded were within the normal range. In conclusion, exposure to toxic fumes and compounds within fuel products may be a contributing factor to bacterial colonization of the respiratory tract in fuel workers.

Culturable bacterial endophytes isolated from Mangrove tree (Rhizophora apiculata Blume) enhance seedling growth in Rice.

PubMed

Deivanai, Subramanian; Bindusara, Amitraghata Santhanam; Prabhakaran, Guruswamy; Bhore, Subhash Janardhan

2014-07-01

Endophytic bacteria do have several potential applications in medicine and in other various sectors of biotechnology including agriculture. Bacterial endophytes need to be explored for their potential applications in agricultural biotechnology. One of the potential applications of bacterial endophytes in agricultural is to enhance the growth of the agricultural crops. Hence, this study was undertaken to explore the plant growth promoting potential application of bacterial endophytes. The objective of this study was to examine the effect of endophytic bacteria from mangrove tree (Rhizophora apiculata Blume) for their efficacy in promoting seedling growth in rice. Eight endophytic bacterial isolates (EBIs) isolated from twig and petiole tissues of the mangrove were identified based on their 16S ribosomal ribonucleic acid (rRNA) gene sequence homology. Separately, surface sterilized paddy seeds were treated with cell-free broth and cell suspension of the EBIs. Rice seedlings were analyzed by various bioassays and data was recorded. The gene sequences of the isolates were closely related to two genera namely, Bacillus and Pantoea. Inoculation of EBIs from R. apiculata with rice seeds resulted in accelerated root and shoot growth with significant increase in chlorophyll content. Among the isolates, Pantoea ananatis (1MSE1) and Bacillus amyloliquefaciens (3MPE1) had shown predominance of activity. Endophytic invasion was recognized by the non-host by rapid accumulation of reactive oxygen species (ROS) and was counteracted by the production of hydrogen peroxide (H2O2) and lipid peroxide. The results demonstrated that EBIs from mangrove tree can increase the fitness of the rice seedlings under controlled conditions. These research findings could be useful to enhance the seedling growth and could serve as foundation in further research on enhancing the growth of the rice crop using endophytic bacteria.

Isolation of bacterial skin flora of healthy sheep, with comparison between frequent and minimal human handling.

PubMed

Haarstad, Amy C; Eisenschenk, Melissa C; Heinrich, Nicole A; Weese, J Scott; McKeever, Patrick J

2014-06-01

Few data are available regarding skin bacterial flora of healthy sheep and meticillin-resistant Staphylococcus carriage. To compare skin, ear and mucosal bacterial populations between minimally and frequently handled sheep; to determine whether the frequency of meticillin-resistant Staphylococcus aureus varied between groups. One hundred and three healthy feedlot and show sheep from eight farms. Swabs were collected from the dorsum, right ear and right nostril of each sheep. Two groups from each farm were evaluated, except from one farm, which had only one group. Bacterial isolates were identified to the genus or species level using phenotypic analysis or matrix-associated laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing and spa typing were performed on isolates of S. aureus. Sixteen bacterial genera were identified and 11 staphylococcal species, including S. aureus. The skin and mucosal bacterial flora were compared between the groups. The only statistically significant difference in bacteria was Streptococcus spp. on the dorsum (P = 0.0088), with carriage being more common in frequently handled sheep. Antimicrobial susceptibility testing did not find meticillin-resistant S. aureus. There was no significant difference in S. aureus carriage in the ear (P = 0.33), nostril (P = 0.43) or dorsum (P = 0.053) between frequently and minimally handled sheep. The S. aureus isolates belonged to six different spa types. Three were of the ST398 lineage. Sheep are a potential source of livestock-associated meticillin-sensitive Staphylococcus aureus ST398. © 2014 ESVD and ACVD.

Inhibitory effect of gut bacteria from the Japanese honey bee, Apis cerana japonica, against Melissococcus plutonius, the causal agent of European foulbrood disease

PubMed Central

Wu, Meihua; Sugimura, Yuya; Iwata, Kyoko; Takaya, Noriko; Takamatsu, Daisuke; Kobayashi, Masaru; Taylor, DeMar; Kimura, Kiyoshi; Yoshiyama, Mikio

2014-01-01

Abstract European foulbrood is a contagious bacterial disease of honey bee larvae. Studies have shown that the intestinal bacteria of insects, including honey bees, act as probiotic organisms. Microbial flora from the gut of the Japanese honey bee, Apis cerana japonica F. (Hymenoptera: Apidae) , were characterized and evaluated for their potential to inhibit the growth of Melissococcus plutonius corrig. (ex White) Bailey and Collins (Lactobacillales: Enterococcaceae) , the causative agent of European foulbrood. Analysis of 16S rRNA gene sequences from 17 bacterial strains isolated by using a culture-dependent method revealed that most isolates belonged to Bacillus, Staphylococcus, and Pantoea. The isolates were screened against the pathogenic bacterium M. plutonius by using an in vitro growth inhibition assay, and one isolate (Acja3) belonging to the genus Bacillus exhibited inhibitory activity against M. plutonius. In addition, in vivo feeding assays revealed that isolate Acja3 decreased the mortality of honey bee larvae infected with M plutonius, suggesting that this bacterial strain could potentially be used as a probiotic agent against European foulbrood. PMID:25368073

Drug Susceptibility Testing of 31 Antimicrobial Agents on Rapidly Growing Mycobacteria Isolates from China.

PubMed

Pang, Hui; Li, Guilian; Zhao, Xiuqin; Liu, Haican; Wan, Kanglin; Yu, Ping

2015-01-01

Several species of rapidly growing mycobacteria (RGM) are now recognized as human pathogens. However, limited data on effective drug treatments against these organisms exists. Here, we describe the species distribution and drug susceptibility profiles of RGM clinical isolates collected from four southern Chinese provinces from January 2005 to December 2012. Clinical isolates (73) were subjected to in vitro testing with 31 antimicrobial agents using the cation-adjusted Mueller-Hinton broth microdilution method. The isolates included 55 M. abscessus, 11 M. fortuitum, 3 M. chelonae, 2 M. neoaurum, and 2 M. septicum isolates. M. abscessus (75.34%) and M. fortuitum (15.07%), the most common species, exhibited greater antibiotic resistance than the other three species. The isolates had low resistance to amikacin, linezolid, and tigecycline, and high resistance to first-line antituberculous agents, amoxicillin-clavulanic acid, rifapentine, dapsone, thioacetazone, and pasiniazid. M. abscessus and M. fortuitum were highly resistant to ofloxacin and rifabutin, respectively. The isolates showed moderate resistance to the other antimicrobial agents. Our results suggest that tigecycline, linezolid, clofazimine, and cefmetazole are appropriate choices for M. abscessus infections. Capreomycin, sulfamethoxazole, tigecycline, clofazimine, and cefmetazole are potentially good choices for M. fortuitum infections. Our drug susceptibility data should be useful to clinicians.

Drug Susceptibility Testing of 31 Antimicrobial Agents on Rapidly Growing Mycobacteria Isolates from China

PubMed Central

Pang, Hui; Li, Guilian; Zhao, Xiuqin; Liu, Haican; Wan, Kanglin; Yu, Ping

2015-01-01

Objectives. Several species of rapidly growing mycobacteria (RGM) are now recognized as human pathogens. However, limited data on effective drug treatments against these organisms exists. Here, we describe the species distribution and drug susceptibility profiles of RGM clinical isolates collected from four southern Chinese provinces from January 2005 to December 2012. Methods. Clinical isolates (73) were subjected to in vitro testing with 31 antimicrobial agents using the cation-adjusted Mueller-Hinton broth microdilution method. The isolates included 55 M. abscessus, 11 M. fortuitum, 3 M. chelonae, 2 M. neoaurum, and 2 M. septicum isolates. Results. M. abscessus (75.34%) and M. fortuitum (15.07%), the most common species, exhibited greater antibiotic resistance than the other three species. The isolates had low resistance to amikacin, linezolid, and tigecycline, and high resistance to first-line antituberculous agents, amoxicillin-clavulanic acid, rifapentine, dapsone, thioacetazone, and pasiniazid. M. abscessus and M. fortuitum were highly resistant to ofloxacin and rifabutin, respectively. The isolates showed moderate resistance to the other antimicrobial agents. Conclusions. Our results suggest that tigecycline, linezolid, clofazimine, and cefmetazole are appropriate choices for M. abscessus infections. Capreomycin, sulfamethoxazole, tigecycline, clofazimine, and cefmetazole are potentially good choices for M. fortuitum infections. Our drug susceptibility data should be useful to clinicians. PMID:26351633

Two poplar-associated bacterial isolates induce additive favorable responses in a constructed plant-microbiome system

DOE PAGES

Jawdy, Sara S.; Gunter, Lee E.; Engle, Nancy L.; ...

2016-04-26

Here, the biological function of the plant-microbiome system is the result of contributions from the host plant and microbiome members. In this work we study the function of a simplified community consisting of Pseudomonas and Burkholderia bacterial strains isolated from Populus hosts and inoculated on axenic Populus cutting in controlled laboratory conditions. Inoculation individually with either bacterial isolate increased root growth relative to uninoculated controls. Root area, photosynthetic efficiency, gene expression and metabolite expression data in individual and dual inoculated treatments indicate that the effects of these bacteria are unique and additive, suggesting that the function of a microbiome communitymore » may be predicted from the additive functions of the individual members.« less

Phytochemical, toxicological and antimicrobial evaluation of lawsonia inermis extracts against clinical isolates of pathogenic bacteria

PubMed Central

2013-01-01

Background The emerging resistance of pathogen against the currently available antimicrobial agents demands the search of new antimicrobial agents. The use of medicinal plants as natural substitute is the paramount area of research to overwhelm the drug resistance of infectious agents. Scientists have not made enough effort on the evaluation of safety of medicinal plant yet. Methods In the present study antimicrobial activity of Lawsonia inermis is investigated against clinical isolates of seven bacteria including four Gram negative (Escherichia coli, Salmonella typhi, Klebsiella spp., Shigella sonnei) and three Gram positive (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis) using disc diffusion method. Four types of Lawsonia inermis extracts were prepared using methanol, chloroform, acetone and water as extraction solvents, while DMSO (Dimethyl sulfoxide) and water as dissolution solvents. The rate and extent of bacterial killing was estimated by time-kill kinetic assay at 1× MIC of each bacterial isolate. The overall safety of Lawsonia inermis extracts was assessed in mice. Results Lawsonia inermis displayed noteworthy antimicrobial activity against both gram positive and gram negative bacterial strains used in the study. The minimum value of MIC for different bacterial strains ranged from 2.31 mg/ml to 9.27 mg/ml. At 1x MIC of each bacterial isolate, 3log10 decrease in CFU was recorded after 6 hours of drug exposure and no growth was observed in almost all tested bacteria after 24 hours of exposure. No sign of toxidrome were observed during in vivo toxicity evaluation in mice at 300 mg/kg concentration. Conclusion In conclusion, the present study provides the scientific rational for medicinal use of Lawsonia inermis. The use of Lawsonia inermis extracts is of great significance as substitute antimicrobial agent in therapeutics. PMID:24289297

Phytochemical, toxicological and antimicrobial evaluation of Lawsonia inermis extracts against clinical isolates of pathogenic bacteria.

PubMed

Gull, Iram; Sohail, Maria; Aslam, Muhammad Shahbaz; Amin Athar, Muhammad

2013-12-01

The emerging resistance of pathogen against the currently available antimicrobial agents demands the search of new antimicrobial agents. The use of medicinal plants as natural substitute is the paramount area of research to overwhelm the drug resistance of infectious agents. Scientists have not made enough effort on the evaluation of safety of medicinal plant yet. In the present study antimicrobial activity of Lawsonia inermis is investigated against clinical isolates of seven bacteria including four Gram negative (Escherichia coli, Salmonella typhi, Klebsiella spp., Shigella sonnei) and three Gram positive (Bacillus subtilis, Staphylococcus aureus, Staphylococcus epidermidis) using disc diffusion method. Four types of Lawsonia inermis extracts were prepared using methanol, chloroform, acetone and water as extraction solvents, while DMSO (Dimethyl sulfoxide) and water as dissolution solvents. The rate and extent of bacterial killing was estimated by time-kill kinetic assay at 1× MIC of each bacterial isolate. The overall safety of Lawsonia inermis extracts was assessed in mice. Lawsonia inermis displayed noteworthy antimicrobial activity against both gram positive and gram negative bacterial strains used in the study. The minimum value of MIC for different bacterial strains ranged from 2.31 mg/ml to 9.27 mg/ml. At 1x MIC of each bacterial isolate, 3log10 decrease in CFU was recorded after 6 hours of drug exposure and no growth was observed in almost all tested bacteria after 24 hours of exposure. No sign of toxidrome were observed during in vivo toxicity evaluation in mice at 300 mg/kg concentration. In conclusion, the present study provides the scientific rational for medicinal use of Lawsonia inermis. The use of Lawsonia inermis extracts is of great significance as substitute antimicrobial agent in therapeutics.

Survival of bacterial isolates exposed to simulated Jovian trapped radiation belt electrons and solar wind protons

NASA Technical Reports Server (NTRS)

Taylor, D. M.; Hagen, C. A.; Renninger, G. M.; Simko, G. J.; Smith, C. D.; Yelinek, J. A.

1972-01-01

With missions to Jupiter, the spacecraft will be exposed for extended duration to solar wind radiation and the Jovian trapped radiation belt. This study is designed to determine the effect of these radiation environments on spacecraft bacterial isolates. The information can be used in the probability of contamination analysis for these missions. A bacterial subpopulation from Mariner Mars 1971 spacecraft (nine sporeforming and three nonsporeforming isolates) plus two comparative organisms, Staphylococcus epidermidis ATCC 17917 and a strain of Bacillus subtilis var. niger, were exposed to 2-, 12-, and 25-MeV electrons at different doses with simultaneous exposure to a vacuum of 0.0013 N/sqm at 20 and -20 C. The radioresistance of the subpopulation was dependent on the isolate, dose, and energy of electrons. Temperature affected the radioresistance of only the sporeforming isolates. Survival data indicated that spores were reduced approximately 1 log/1500 J/kg, while nonsporeforming isolates (micrococci) were reduced 1.5 to 2 logs/1500 J/kg with the exception of an apparent radioresistant isolate whose resistance approached that of the spores. The subpopulation was found to be less resistant to lower energy than to higher energy electrons.

Comparison of different methods for isolation of bacterial DNA from retail oyster tissues

USDA-ARS?s Scientific Manuscript database

Oysters are filter-feeders that bio-accumulate bacteria in water while feeding. To evaluate the bacterial genomic DNA extracted from retail oyster tissues, including the gills and digestive glands, four isolation methods were used. Genomic DNA extraction was performed using the Allmag™ Blood Genomic...

Efficacy of a marine bacterial nuclease against biofilm forming microorganisms isolated from chronic rhinosinusitis.

PubMed

Shields, Robert C; Mokhtar, Norehan; Ford, Michael; Hall, Michael J; Burgess, J Grant; ElBadawey, Mohamed Reda; Jakubovics, Nicholas S

2013-01-01

The persistent colonization of paranasal sinus mucosa by microbial biofilms is a major factor in the pathogenesis of chronic rhinosinusitis (CRS). Control of microorganisms within biofilms is hampered by the presence of viscous extracellular polymers of host or microbial origin, including nucleic acids. The aim of this study was to investigate the role of extracellular DNA in biofilm formation by bacteria associated with CRS. Obstructive mucin was collected from patients during functional endoscopic sinus surgery. Examination of the mucous by transmission electron microscopy revealed an acellular matrix punctuated occasionally with host cells in varying states of degradation. Bacteria were observed in biofilms on mucosal biopsies, and between two and six different species were isolated from each of 20 different patient samples. In total, 16 different bacterial genera were isolated, of which the most commonly identified organisms were coagulase-negative staphylococci, Staphylococcus aureus and α-haemolytic streptococci. Twenty-four fresh clinical isolates were selected for investigation of biofilm formation in vitro using a microplate model system. Biofilms formed by 14 strains, including all 9 extracellular nuclease-producing bacteria, were significantly disrupted by treatment with a novel bacterial deoxyribonuclease, NucB, isolated from a marine strain of Bacillus licheniformis. Extracellular biofilm matrix was observed in untreated samples but not in those treated with NucB and extracellular DNA was purified from in vitro biofilms. Our data demonstrate that bacteria associated with CRS form robust biofilms which can be reduced by treatment with matrix-degrading enzymes such as NucB. The dispersal of bacterial biofilms with NucB may offer an additional therapeutic target for CRS sufferers.

Complete Genome Sequence of Ralstonia solanacearum FJAT-1458, a Potential Biocontrol Agent for Tomato Wilt.

PubMed

Chen, Deju; Liu, Bo; Zhu, Yujing; Wang, Jieping; Chen, Zheng; Che, Jiamei; Zheng, Xuefang; Chen, Xiaoqiang

2017-04-06

An avirulent strain of Ralstonia solanacearum FJAT-1458 was isolated from a living tomato. Here, we report the complete R. solanacearum FJAT-1458 genome sequence of 6,059,899 bp and 5,241 genes. This bacterial strain is a potential candidate as a biocontrol agent in the form of a plant vaccine for bacterial wilt. Copyright © 2017 Chen et al.

Inactivation of bacterial biothreat agents in water, a review

PubMed Central

Rice, E. W.

2016-01-01

Water supplies and water distribution systems have been identified as potential targets for contamination by bacterial biothreat agents. Since the 2001 Bacillus anthracis bioterrorist attacks, additional efforts have been aimed at research to characterize biothreat organisms in regards to their susceptibility to disinfectants and technologies currently in use for potable water. Here, we present a review of research relevant to disinfection of bacteria with the potential to pose a severe threat to public health and safety, and their potential surrogates. The efficacy of chlorine, monochloramine, chlorine dioxide, and ultraviolet light to inactivate each organism in suspension is described. The complexities of disinfection under varying water conditions and when the organisms are associated with biofilms in distribution systems are discussed. PMID:25473971

In vitro activity of AT-4140 against clinical bacterial isolates.

PubMed

Kojima, T; Inoue, M; Mitsuhashi, S

1989-11-01

The activity of AT-4140, a new fluoroquinolone, was evaluated against a wide range of clinical bacterial isolates and compared with those of existing analogs. AT-4140 had a broad spectrum and a potent activity against gram-positive and -negative bacteria, including Legionella spp. and Bacteroides fragilis. The activity of AT-4140 against gram-positive and -negative cocci, including Acinetobacter calcoaceticus, was higher than those of ciprofloxacin, ofloxacin, and norfloxacin. Its activity against gram-negative rods was generally comparable to that of ciprofloxacin. Some isolates of methicillin-resistant Staphylococcus aureus (MIC of methicillin, greater than or equal to 12.5 micrograms/ml) were resistant to existing quinolones, but many of them were still susceptible to AT-4140 at concentrations below 0.39 micrograms/ml. The MICs of AT-4140, ciprofloxacin, ofloxacin, and norfloxacin for 90% of clinical isolates of methicillin-resistant S. aureus were 0.2, 12.5, 6.25, and 100 micrograms/ml, respectively. AT-4140 was bactericidal for each of 20 clinical isolates of Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens, and Pseudomonas aeruginosa at concentrations near the MICs. AT-4140 inhibited the supercoiling activity of DNA gyrase from E. coli.

Degradation and mineralization of atrazine by a soil bacterial isolate.

PubMed Central

Radosevich, M; Traina, S J; Hao, Y L; Tuovinen, O H

1995-01-01

An atrazine-degrading bacterial culture was isolated from an agricultural soil previously impacted by herbicide spills. The organism was capable of using atrazine under aerobic conditions as the sole source of C and N. Cyanuric acid could replace atrazine as the sole source of N, indicating that the organism was capable of ring cleavage. Ring cleavage was confirmed in 14CO2 evolution experiments with [U-14C-ring]atrazine. Between 40 and 50% of ring-14C was mineralized to 14CO2. [14C]biuret and [14C]urea were detected in spent culture media. Cellular assimilation of 14C was negligible, in keeping with the fully oxidized valence of the ring carbon. Chloride release was stoichiometric. The formation of ammonium during atrazine degradation was below the stoichiometric amount, suggesting a deficit due to cellular assimilation and metabolite-N accumulation. With excess glucose and with atrazine as the sole N source, free ammonium was not detected, suggesting assimilation into biomass. The organism degraded atrazine anaerobically in media which contained (i) atrazine only, (ii) atrazine and glucose, and (iii) atrazine, glucose, and nitrate. To date, this is the first report of a pure bacterial isolate with the ability to cleave the s-triazine ring structure of atrazine. It was also concluded that this bacterium was capable of dealkylation, dechlorination, and deamination in addition to ring cleavage. PMID:7887609

Historical distribution and host-vector diversity of Francisella tularensis, the causative agent of tularemia, in Ukraine.

PubMed

Hightower, Jake; Kracalik, Ian T; Vydayko, Nataliya; Goodin, Douglas; Glass, Gregory; Blackburn, Jason K

2014-10-16

Francisella tularensis, the causative agent of tularemia, is a zoonotic agent that remains across much of the northern hemisphere, where it exists in enzootic cycles. In Ukraine, tularemia has a long history that suggests a need for sustained surveillance in natural foci. To better characterize the host-vector diversity and spatial distribution of tularemia, we analyzed historical data from field collections carried out from 1941 to 2008. We analyzed the spatial-temporal distribution of bacterial isolates collected from field samples. Isolates were characterized by source and dominant land cover type. To identify environmental persistence and spatial variation in the source of isolation, we used the space-time permutation and multinomial models in SaTScan. A total of 3,086 positive isolates were taken from 1,084 geographic locations. Isolation of F. tularensis was more frequent among arthropods [n = 2,045 (66.3%)] followed by mammals [n = 619 (20.1%)], water [n = 393 (12.7%)], and farm produce [n = 29 (0.94%)], respectively. Four areas of persistent bacterial isolation were identified. Water and farm produce as sources of bacterial isolation were clustered. Our findings confirm the presence of long-standing natural foci of F. tularensis in Ukraine. Given the history of tularemia as well as its environmental persistence there exists a possibility of (re)emergence in human populations. Heterogeneity in the distribution of tularemia isolate recovery related to land cover type supports the theory of natural nidality and clusters identify areas to target potential sources of the pathogen and improve surveillance.

Isolation and characterization of anti-SEB peptides using magnetic sorting and bacterial peptide display library technology

NASA Astrophysics Data System (ADS)

Pennington, Joseph M.; Kogot, Joshua M.; Sarkes, Deborah A.; Pellegrino, Paul M.; Stratis-Cullum, Dimitra N.

2012-06-01

Peptide display libraries offer an alternative method to existing antibody development methods enabling rapid isolation of highly stable reagents for detection of new and emerging biological threats. Bacterial display libraries are used to isolate new peptide reagents within 1 week, which is simpler and timelier than using competing display library technology based on phage or yeast. Using magnetic sorting methods, we have isolated peptide reagents with high affinity and specificity to staphylococcal enterotoxin B (SEB), a suspected food pathogen. Flow cytometry methods were used for on-cell characterization and the binding affinity (Kd) of this new peptide reagent was determined to be 56 nm with minimal cross-reactivity to other proteins. These results demonstrated that magnetic sorting for new reagents using bacterial display libraries is a rapid and effective method and has the potential for current and new and emerging food pathogen targets.

A standard bacterial isolate set for research on contemporary dairy spoilage.

PubMed

Trmčić, A; Martin, N H; Boor, K J; Wiedmann, M

2015-08-01

Food spoilage is an ongoing issue that could be dealt with more efficiently if some standardization and unification was introduced in this field of research. For example, research and development efforts to understand and reduce food spoilage can greatly be enhanced through availability and use of standardized isolate sets. To address this critical issue, we have assembled a standard isolate set of dairy spoilers and other selected nonpathogenic organisms frequently associated with dairy products. This publicly available bacterial set consists of (1) 35 gram-positive isolates including 9 Bacillus and 15 Paenibacillus isolates and (2) 16 gram-negative isolates including 4 Pseudomonas and 8 coliform isolates. The set includes isolates obtained from samples of pasteurized milk (n=43), pasteurized chocolate milk (n=1), raw milk (n=1), cheese (n=2), as well as isolates obtained from samples obtained from dairy-powder production (n=4). Analysis of growth characteristics in skim milk broth identified 16 gram-positive and 13 gram-negative isolates as psychrotolerant. Additional phenotypic characterization of isolates included testing for activity of β-galactosidase and lipolytic and proteolytic enzymes. All groups of isolates included in the isolate set exhibited diversity in growth and enzyme activity. Source data for all isolates in this isolate set are publicly available in the FoodMicrobeTracker database (http://www.foodmicrobetracker.com), which allows for continuous updating of information and advancement of knowledge on dairy-spoilage representatives included in this isolate set. This isolate set along with publicly available isolate data provide a unique resource that will help advance knowledge of dairy-spoilage organisms as well as aid industry in development and validation of new control strategies. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Epidemiology of bacterial isolates among pediatric cancer patients from a tertiary care oncology center in North India.

PubMed

Kapoor, G; Sachdeva, N; Jain, S

2014-01-01

Infections are a major cause of morbidity and mortality in pediatric oncology. Resistance pattern of bacterial isolates determine empiric antibiotic therapy and influence outcome. This study was planned to determine profile of bacterial isolates and their antibiotic resistance pattern among pediatric cancer patients. It was a retrospective, single institutional study. The study was carried out in the department of pediatric hematology-oncology of a tertiary care cancer centre in north India over a period of 24 months (2012-2014). Microbiological data pertaining to pediatric cancer patients, less than 18 yrs of age was analysed. Hence, 238 bacterial isolates were cultured from among 1757 blood, urine and other specimens. Gram negative bacteria were the most common (74%) pathogens identified and E. coli and Klebsiella comprised 80% of them. A high incidence of extended spectrum beta lactamase producing organisms (84%), beta-lactam beta-lactamase inhibitor (78%) and carbapenem resistance was observed (29%). Blood stream infection with multi-drug resistant Klebsiella was associated with high mortality. The gram positive bacteria isolated were predominantly staphylococcus aureus and were antibiotic sensitive. Reduction in the number of culture positive isolates in the second year of our study was probably due to rigorous implementation of infection control measures. These results on microbiologic profile and antibiotic sensitivity pattern of the isolates will be extremely helpful in revision of antibiotic guidelines for our patients and in developing strategies for coping with high prevalence of multi-drug resistance. Antibiotic stewardship and strict implementation of infection control practices will be important components of this effort.

Survival of bacterial isolates exposed to simulated Jovian trapped radiation belt electrons and solar wind protons

NASA Technical Reports Server (NTRS)

Taylor, D. M.; Hagen, C. A.; Renninger, G. M.; Simko, G. J.; Smith, C. D.; Yelinek, J. A.

1973-01-01

With missions to Jupiter, the spacecraft will be exposed for extended durations to solar wind radiation and the Jovian trapped radiation belt. This study is designed to determine the effect of these radiation environments on spacecraft bacterial isolates. The information can be used in the probability of contamination analysis for these missions. A bacterial subpopulation from Mariner Mars 1971 spacecraft (nine spore-forming and three non-spore-forming isolates) plus two comparative organisms, Staphylococcus epidermidis ATCC 17917 and a strain of Bacillus subtilis var. niger, were exposed to 2, 12, and 25 MeV electrons at different doses with simultaneous exposure to a vacuum of 1.3 x 10(-4) N m-2 at 20 and -20 degrees C. The radioresistance of the subpopulation was dependent on the isolate, dose and energy of electrons. Temperature affected the radioresistance of only the spore-forming isolates. Survival data indicated that spores were reduced approximately 1 log/1500 J kg-1 (10 J kg-1=1 krad), while non-spore-forming isolates (micrococci) were reduced 1.5-2 logs/1500 J kg-1 with the exception of an apparent radioresistant isolate whose resistance approached that of the spores. The subpopulation was found to be less resistant to lower energy than to higher energy electrons. The bacterial isolates were exposed to 3 keV protons under the same conditions as the electrons with a total fluence of 1.5 x 10(13) p cm-2 and a dose rate of 8.6 x 10(9) p cm-2 s-1. The results showed that only 20% of S. epidermidis and 45% of B. subtilis populations survived exposure to the 3 keV protons, while the mean survival of the spacecraft subpopulation was 45% with a range from 31.8% (non-spore-former) to 64.8% (non-spore-former). No significant difference existed between spore-forming and non-spore-forming isolates.

Bacterial Infections in Children With Acute Myeloid Leukemia Receiving Ciprofloxacin Prophylaxis.

PubMed

Al Omar, Suha; Anabtawi, Nadine; Al Qasem, Wiam; Rihani, Rawad

2017-04-01

The aim of the study was to describe the incidence and type of bacterial infections associated with the use of ciprofloxacin prophylaxis as single agent in pediatric patients with acute myeloid leukemia (AML). This was a retrospective review of all patients with AML, who were treated according to the AML02 protocol between 2011 and 2015. The medical records were reviewed for any positive cultures from the initiation of the protocol until death or protocol discontinuation. Patient demographics, type of infections, type of isolated bacteria, and intensive care unit admissions were recorded. A total of 50 patients were evaluated, who were of a mean age of 8 years±5.1 (SD). We identified 77 episodes of bacterial infections in 42 (84%) patients. Among those bacterial infections, 73 episodes were with bacteremia and included 45 (62%) gram-positive bacterial infections, 24 (33%) gram-negative bacterial infections, and 4 (6%) mixed gram-negative and gram-positive bacterial infections. Coagulase-negative Staphylococcus and Viridans streptococci were the most commonly isolated bacteria in 33% and 30% of the episodes, respectively. Seventeen (45%) patients with bacteremia required intensive care unit admission. A high rate of bacterial infection was detected in patients who received the AML02 protocol, mainly gram-positive bacterial infections. The prophylactic regimen should be reconsidered for its efficacy, and other antibacterial prophylaxis may be used.

Antagonistic activity of Bacillus subtilis SB1 and its biocontrol effect on tomato bacterial wilt

USDA-ARS?s Scientific Manuscript database

A potential biocontrol agent of bacterial wilt, Bacillus subtilis SB1, isolated from tomato roots, showed a broad-spectrum of antimicrobial activity in in vitro experiments. It inhibited the growth of many plant pathogens, including Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, Fusarium ox...

Spatial pattern in Antarctica: what can we learn from Antarctic bacterial isolates?

PubMed

Chong, Chun Wie; Goh, Yuh Shan; Convey, Peter; Pearce, David; Tan, Irene Kit Ping

2013-09-01

A range of small- to moderate-scale studies of patterns in bacterial biodiversity have been conducted in Antarctica over the last two decades, most suggesting strong correlations between the described bacterial communities and elements of local environmental heterogeneity. However, very few of these studies have advanced interpretations in terms of spatially associated patterns, despite increasing evidence of patterns in bacterial biogeography globally. This is likely to be a consequence of restricted sampling coverage, with most studies to date focusing only on a few localities within a specific Antarctic region. Clearly, there is now a need for synthesis over a much larger spatial to consolidate the available data. In this study, we collated Antarctic bacterial culture identities based on the 16S rRNA gene information available in the literature and the GenBank database (n > 2,000 sequences). In contrast to some recent evidence for a distinct Antarctic microbiome, our phylogenetic comparisons show that a majority (~75 %) of Antarctic bacterial isolates were highly similar (≥99 % sequence similarity) to those retrieved from tropical and temperate regions, suggesting widespread distribution of eurythermal mesophiles in Antarctic environments. However, across different Antarctic regions, the dominant bacterial genera exhibit some spatially distinct diversity patterns analogous to those recently proposed for Antarctic terrestrial macroorganisms. Taken together, our results highlight the threat of cross-regional homogenisation in Antarctic biodiversity, and the imperative to include microbiota within the framework of biosecurity measures for Antarctica.

Antibacterial Activity of the Isolation Ethyl Acetate-Soluble Extract Noni Fruit (Morindra citrifolia L.) against Meat Bacterial Decay

NASA Astrophysics Data System (ADS)

Nugraheni, E. R.; Nurrakhman, M. B. E.; Munawaroh, H.; Saputri, L.

2017-02-01

Noni (Morindra citrifolia L.) is native to Indonesia which have medicinal properties. One of them as an antibacterial. This study aims to determine the antibacterial activity of isolates from the ethanol extract noni fruit to bacterial decay meat is Bacillus licheniformis, Klebsiella pneumonia, Bacillus alvei, Acinetobacter calcoaceticus, and Staphylococcus saprophyticus. The extraction process using the maceration method, and then made a partition by centrifugation ethyl acetate. Soluble part partition showed bacterial growth inhibition activity of the strong to very strong. Furthermore, the ethyl acetate soluble partition on preparative thin layer chromatography produced 5 isolates. Isolates obtained antibacterial activity test performed with a concentration of 20% and 30%. The results of antibacterial test against bacteria test isolates, showing isolates A can not inhibit the growth of bacteria, isolates B and C have medium activity and strong, isolates D and E isolates have activity against bacteria that were tested. MIC and MBC test results showed that the isolates B gives an inhibitory effect (bacteriostatic) against all bacteria. Content analysis of compounds by TLC using the reagents cerium (IV) sulfate indicates a phenol group. Isolates B contains a major compound which can be used as an antibacterial candidate in food preservation replace chemical preservatives.

Elucidating Duramycin’s Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope

DOE PAGES

Hasim, Sahar; Allison, David P.; Mendez, Berlin; ...

2018-02-14

The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus-derived bacterial isolates to determine species selectivity.more » Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE) in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin’s mode of action and a better understanding of its selectivity.« less

Elucidating Duramycin’s Bacterial Selectivity and Mode of Action on the Bacterial Cell Envelope

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hasim, Sahar; Allison, David P.; Mendez, Berlin

The use of naturally occurring antimicrobial peptides provides a promising route to selectively target pathogenic agents and to shape microbiome structure. Lantibiotics, such as duramycin, are one class of bacterially produced peptidic natural products that can selectively inhibit the growth of other bacteria. However, despite longstanding characterization efforts, the microbial selectivity and mode of action of duramycin are still obscure. We describe here a suite of biological, chemical, and physical characterizations that shed new light on the selective and mechanistic aspects of duramycin activity. Bacterial screening assays have been performed using duramycin and Populus-derived bacterial isolates to determine species selectivity.more » Lipidomic profiles of selected resistant and sensitive strains show that the sensitivity of Gram-positive bacteria depends on the presence of phosphatidylethanolamine (PE) in the cell membrane. Further the surface and interface morphology were studied by high resolution atomic force microscopy and showed a progression of cellular changes in the cell envelope after treatment with duramycin for the susceptible bacterial strains. Together, these molecular and cellular level analyses provide insight into duramycin’s mode of action and a better understanding of its selectivity.« less

Indoleacetic acid production and plant growth promoting potential of bacterial endophytes isolated from rice (Oryza sativa L.) seeds.

PubMed

Shahzad, Raheem; Waqas, Muhammad; Khan, Abdul Latif; Al-Hosni, Khadija; Kang, Sang-Mo; Seo, Chang-Woo; Lee, In-Jung

2017-06-01

Bacterial endophytes from the phyllosphere and rhizosphere have been used to produce bioactive metabolites and to promote plant growth. However, little is known about the endophytes residing in seeds. This study aimed to isolate and identify seed-borne bacterial endophytes from rice and elucidate their potential for phytohormone production and growth enhancement. The isolated endophytes included Micrococcus yunnanensis RWL-2, Micrococcus luteus RWL-3, Enterobacter soli RWL-4, Leclercia adecarboxylata RWL-5, Pantoea dispersa RWL-6, and Staphylococcus epidermidis RWL-7, which were identified using 16S rRNA sequencing and phylogenetic analysis. These strains were analyzed for indoleacetic acid (IAA) production by using GC-MS and IAA was found in the range of 11.50 ± 0.77 μg ml -1 to 38.80 ± 1.35 μg ml -1 . We also assessed the strains for plant growth promoting potential because these isolates were able to produce IAA in pure culture. Most of the growth attributes of rice plants (shoot and root length, fresh and dry biomass, and chlorophyll content) were significantly increased by bacterial endophytes compared to the controls. These results show that IAA producing bacterial endophytes can improve hostplant growth traits and can be used as bio-fertilizers.

Aerobic cyanide degradation by bacterial isolates from cassava factory wastewater

PubMed Central

Kandasamy, Sujatha; Dananjeyan, Balachandar; Krishnamurthy, Kumar; Benckiser, Gero

2015-01-01

Ten bacterial strains that utilize cyanide (CN) as a nitrogen source were isolated from cassava factory wastewater after enrichment in a liquid media containing sodium cyanide (1 mM) and glucose (0.2% w/v). The strains could tolerate and grow in cyanide concentrations of up to 5 mM. Increased cyanide levels in the media caused an extension of lag phase in the bacterial growth indicating that they need some period of acclimatisation. The rate of cyanide removal by the strains depends on the initial cyanide and glucose concentrations. When initial cyanide and glucose concentrations were increased up to 5 mM, cyanide removal rate increased up to 63 and 61 per cent by Bacillus pumilus and Pseudomonas putida. Metabolic products such as ammonia and formate were detected in culture supernatants, suggesting a direct hydrolytic pathway without an intermediate formamide. The study clearly demonstrates the potential of aerobic treatment with cyanide degrading bacteria for cyanide removal in cassava factory wastewaters. PMID:26413045

Aerobic cyanide degradation by bacterial isolates from cassava factory wastewater.

PubMed

Kandasamy, Sujatha; Dananjeyan, Balachandar; Krishnamurthy, Kumar; Benckiser, Gero

2015-01-01

Ten bacterial strains that utilize cyanide (CN) as a nitrogen source were isolated from cassava factory wastewater after enrichment in a liquid media containing sodium cyanide (1 mM) and glucose (0.2% w/v). The strains could tolerate and grow in cyanide concentrations of up to 5 mM. Increased cyanide levels in the media caused an extension of lag phase in the bacterial growth indicating that they need some period of acclimatisation. The rate of cyanide removal by the strains depends on the initial cyanide and glucose concentrations. When initial cyanide and glucose concentrations were increased up to 5 mM, cyanide removal rate increased up to 63 and 61 per cent by Bacillus pumilus and Pseudomonas putida. Metabolic products such as ammonia and formate were detected in culture supernatants, suggesting a direct hydrolytic pathway without an intermediate formamide. The study clearly demonstrates the potential of aerobic treatment with cyanide degrading bacteria for cyanide removal in cassava factory wastewaters.

IDENTIFICATION, ISOLATION AND CHARACTERIZATION OF THE INFECTIOUS HEPATITIS (HEPATITIS A) AGENT

EPA Science Inventory

The research program has the overall objective of combining the techniques of electron microscopy, ultracentrifugation, column chromatography, tissue culture and serology to identify, isolate and characterize the etiologic agent of infectious hepatitis, to propagate it in cell cu...

Aerobic De-Epoxydation of Trichothecene Mycotoxins by a Soil Bacterial Consortium Isolated Using In Situ Soil Enrichment.

PubMed

He, Wei-Jie; Yuan, Qing-Song; Zhang, You-Bing; Guo, Mao-Wei; Gong, An-Dong; Zhang, Jing-Bo; Wu, Ai-Bo; Huang, Tao; Qu, Bo; Li, He-Ping; Liao, Yu-Cai

2016-09-24

Globally, the trichothecene mycotoxins deoxynivalenol (DON) and nivalenol (NIV) are among the most widely distributed mycotoxins that contaminate small grain cereals. In this study, a bacterial consortium, PGC-3, with de-epoxydation activity was isolated from soil by an in situ soil enrichment method. Screening of 14 soil samples that were sprayed with DON revealed that 4 samples were able to biotransform DON into de-epoxydized DON (dE-DON). Among these, the PGC-3 consortium showed the highest and most stable activity to biotransform DON into dE-DON and NIV into dE-NIV. PGC-3 exhibited de-epoxydation activity at a wide range of pH (5-10) and temperatures (20-37 °C) values under aerobic conditions. Sequential subculturing with a continued exposure to DON substantially reduced the microbial population diversity of this consortium. Analyses of the 16S rDNA sequences indicated that PGC-3 comprised 10 bacterial genera. Among these, one species, Desulfitobacterium, showed a steady increase in relative abundance, from 0.03% to 1.55% (a 52-fold increase), as higher concentrations of DON were used in the subculture media, from 0 to 500 μg/mL. This study establishes the foundation to further develop bioactive agents that can detoxify trichothecene mycotoxins in cereals and enables for the characterization of detoxifying genes and their regulation.

Aerobic De-Epoxydation of Trichothecene Mycotoxins by a Soil Bacterial Consortium Isolated Using In Situ Soil Enrichment

PubMed Central

He, Wei-Jie; Yuan, Qing-Song; Zhang, You-Bing; Guo, Mao-Wei; Gong, An-Dong; Zhang, Jing-Bo; Wu, Ai-Bo; Huang, Tao; Qu, Bo; Li, He-Ping; Liao, Yu-Cai

2016-01-01

Globally, the trichothecene mycotoxins deoxynivalenol (DON) and nivalenol (NIV) are among the most widely distributed mycotoxins that contaminate small grain cereals. In this study, a bacterial consortium, PGC-3, with de-epoxydation activity was isolated from soil by an in situ soil enrichment method. Screening of 14 soil samples that were sprayed with DON revealed that 4 samples were able to biotransform DON into de-epoxydized DON (dE-DON). Among these, the PGC-3 consortium showed the highest and most stable activity to biotransform DON into dE-DON and NIV into dE-NIV. PGC-3 exhibited de-epoxydation activity at a wide range of pH (5–10) and temperatures (20–37 °C) values under aerobic conditions. Sequential subculturing with a continued exposure to DON substantially reduced the microbial population diversity of this consortium. Analyses of the 16S rDNA sequences indicated that PGC-3 comprised 10 bacterial genera. Among these, one species, Desulfitobacterium, showed a steady increase in relative abundance, from 0.03% to 1.55% (a 52-fold increase), as higher concentrations of DON were used in the subculture media, from 0 to 500 μg/mL. This study establishes the foundation to further develop bioactive agents that can detoxify trichothecene mycotoxins in cereals and enables for the characterization of detoxifying genes and their regulation. PMID:27669304

The Unculturables: targeted isolation of bacterial species associated with canine periodontal health or disease from dental plaque.

PubMed

Davis, Ian J; Bull, Christopher; Horsfall, Alexander; Morley, Ian; Harris, Stephen

2014-08-01

The current inability to culture the entirety of observed bacteria is well known and with the advent of ever more powerful molecular tools, that can survey bacterial communities at previously unattainable depth, the gap in our capacity to culture and define all of these species increases exponentially. This gap has essentially become the rate limiting step in determining how the knowledge of which species are present in a sample can be applied to understand the role of these species in an ecosystem or disease process. A case in point is periodontal disease, which is the most widespread oral disease in dogs. If untreated the disease results in significant pain, eventual loss of the dentition and potentially an increased risk of systemic diseases. Previous molecular based studies have identified the bacterial species associated with periodontal disease in dogs; however without cultured strains from many of these species it has not been possible to study whether they play a role in the disease process. Using a quantitative polymerase chain reaction (qPCR) directed approach a range of microbiological media were screened and optimized to enrich for previously uncultivated target species. A systematic screening methodology was then employed to isolate the species of interest. In cases where the target species were not cultivable in isolation, helper strains grown underneath a nitrocellulose membrane were used to provide the necessary growth factors. This guided media optimization approach enabled the purification of 14 species, 8 of which we had previously been unable to cultivate in isolation. It is also applicable to the targeted isolation of isolates from species that have previously been cultured (for example to study intra-species variation) as demonstrated by the successful isolation of 6 targeted isolates of already cultured species. To our knowledge this is the first time this combination of qPCR guided media optimization, strategic screening and helper strain

Isolation and identification of bacterial pathogen from mastitis milk in Central Java Indonesia

NASA Astrophysics Data System (ADS)

Harjanti, D. W.; Ciptaningtyas, R.; Wahyono, F.; Setiatin, ET

2018-01-01

Mastitis is a multi-etiologic disease of the mammary gland characterized mainly by reduction in milk production and milk quality due to intramammary infection by pathogenic bacteria. Nearly 83% of lactating dairy cows in Indonesia are infected with mastitis in various inflammation degrees. This study was conducted to isolate and identify the pathogen in milk collected from mastitis-infected dairy cows. The study was carried out in ten smallholder dairy farms in Central Java Indonesia based on animal examination, California mastitis test, isolation bacterial pathogens, Gram staining, Catalase and Coagulase test, and identification of bacteria species using Vitek. Bacteriological examination of milk samples revealed 15 isolates where Streptococcus was predominant species (73.3%) and the coagulase negative Staphylococcus species was identified at the least bacteria (26.7%). The Streptococcus bacteria found were Streptococcus uberis (2 isolates), Streptococcus sanguinis(6 isolates), Streptococcus dysgalactiaessp dysgalactiae(1 isolate) , Streptococcus mitis (1 isolate) and Streptococcus agalactiae (1 isolate). The Staphylococcus isolates comprising of Staphylococcus simulans (1 isolate) and Staphylococcus chromogens (3 isolates). Contamination of raw milkwith pathogenic bacteria can cause outbreaks of human disease (milk borne disease). Thus, proper milk processing method that couldinhibit the growth or kill these pathogenic bacteria is important to ensure the safety of milk and milk products.

Isolation and characterization of two new methanesulfonic acid-degrading bacterial isolates from a Portuguese soil sample.

PubMed

De Marco, P; Murrell, J C; Bordalo, A A; Moradas-Ferreira, P

2000-02-01

Two novel bacterial strains that can utilize methanesulfonic acid as a source of carbon and energy were isolated from a soil sample collected in northern Portugal. Morphological, physiological, biochemical and molecular biological characterization of the two isolates indicate that strain P1 is a pink-pigmented facultative methylotroph belonging to the genus Methylobacterium, while strain P2 is a restricted methylotroph belonging to the genus Hyphomicrobium. Both strains are strictly aerobic, degrade methanesulfonate, and release small quantities of sulfite into the medium. Growth on methanesulfonate induces a specific polypeptide profile in each strain. This, together with the positive hybridization to a DNA probe that carries the msm genes of Methylosulfonomonas methylovora strain M2, strongly endorses the contention that a methanesulfonic acid monooxygenase related to that found in the previously known methanesulfonate-utilizing bacteria is present in strains P1 and P2. The isolation of bacteria containing conserved msm genes from diverse environments and geographical locations supports the hypothesis that a common enzyme may be globally responsible for the oxidation of methanesulfonate by natural methylotrophic communities.

The kuru infectious agent is a unique geographic isolate distinct from Creutzfeldt–Jakob disease and scrapie agents

PubMed Central

Manuelidis, Laura; Chakrabarty, Trisha; Miyazawa, Kohtaro; Nduom, Nana-Aba; Emmerling, Kaitlin

2009-01-01

Human sporadic Creutzfeldt–Jakob disease (sCJD), endemic sheep scrapie, and epidemic bovine spongiform encephalopathy (BSE) are caused by a related group of infectious agents. The new U.K. BSE agent spread to many species, including humans, and clarifying the origin, specificity, virulence, and diversity of these agents is critical, particularly because infected humans do not develop disease for many years. As with viruses, transmissible spongiform encephalopathy (TSE) agents can adapt to new species and become more virulent yet maintain fundamentally unique and stable identities. To make agent differences manifest, one must keep the host genotype constant. Many TSE agents have revealed their independent identities in normal mice. We transmitted primate kuru, a TSE once epidemic in New Guinea, to mice expressing normal and ≈8-fold higher levels of murine prion protein (PrP). High levels of murine PrP did not prevent infection but instead shortened incubation time, as would be expected for a viral receptor. Sporadic CJD and BSE agents and representative scrapie agents were clearly different from kuru in incubation time, brain neuropathology, and lymphoreticular involvement. Many TSE agents can infect monotypic cultured GT1 cells, and unlike sporadic CJD isolates, kuru rapidly and stably infected these cells. The geographic independence of the kuru agent provides additional reasons to explore causal environmental pathogens in these infectious neurodegenerative diseases. PMID:19633190

External Bacterial Flora and Antimicrobial Susceptibility Patterns of Staphylococcus spp. and Pseudomonas spp. Isolated from Two Household Cockroaches, Blattella germanica and Blatta orientalis.

PubMed

Menasria, Taha; Tine, Samir; Mahcene, Djaouida; Benammar, Leyla; Megri, Rochdi; Boukoucha, Mourad; Debabza, Manel

2015-04-01

A study was performed to estimate the prevalence of the external bacterial flora of two domestic cockroaches (Blattella germanica and Blatta orientalis) collected from households in Tebessa (northeast Algeria). Three major bacterial groups were cultured (total aerobic, enterobacteria, and staphylococci) from 14 specimens of cockroaches, and antibiotic susceptibility was tested for both Staphylococcus and Pseudomonas isolates. Culturing showed that the total bacterial load of cockroaches from different households were comparable (P<0.001) and enterobacteria were the predominant colonizers of the insect surface, with a bacterial load of (2.1 × 10⁵ CFU/insect), whereas the staphylococci group was the minority. Twenty-eight bacterial species were isolated, and susceptibility patterns showed that most of the staphylococci isolates were highly susceptible to chloramphenicol, gentamycin, pristinamycin, ofloxacin, clindamycin, and vancomycin; however, Pseudomonas strains exhibited resistance to amoxicillin/clavulanic acid, imipenem, and the second-generation antibiotic cephalosporin cefuroxime. Copyright © 2015 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

Propionibacterium acnes Bacteriophages Display Limited Genetic Diversity and Broad Killing Activity against Bacterial Skin Isolates

PubMed Central

Marinelli, Laura J.; Fitz-Gibbon, Sorel; Hayes, Clarmyra; Bowman, Charles; Inkeles, Megan; Loncaric, Anya; Russell, Daniel A.; Jacobs-Sera, Deborah; Cokus, Shawn; Pellegrini, Matteo; Kim, Jenny; Miller, Jeff F.; Hatfull, Graham F.; Modlin, Robert L.

2012-01-01

ABSTRACT Investigation of the human microbiome has revealed diverse and complex microbial communities at distinct anatomic sites. The microbiome of the human sebaceous follicle provides a tractable model in which to study its dominant bacterial inhabitant, Propionibacterium acnes, which is thought to contribute to the pathogenesis of the human disease acne. To explore the diversity of the bacteriophages that infect P. acnes, 11 P. acnes phages were isolated from the sebaceous follicles of donors with healthy skin or acne and their genomes were sequenced. Comparative genomic analysis of the P. acnes phage population, which spans a 30-year temporal period and a broad geographic range, reveals striking similarity in terms of genome length, percent GC content, nucleotide identity (>85%), and gene content. This was unexpected, given the far-ranging diversity observed in virtually all other phage populations. Although the P. acnes phages display a broad host range against clinical isolates of P. acnes, two bacterial isolates were resistant to many of these phages. Moreover, the patterns of phage resistance correlate closely with the presence of clustered regularly interspaced short palindromic repeat elements in the bacteria that target a specific subset of phages, conferring a system of prokaryotic innate immunity. The limited diversity of the P. acnes bacteriophages, which may relate to the unique evolutionary constraints imposed by the lipid-rich anaerobic environment in which their bacterial hosts reside, points to the potential utility of phage-based antimicrobial therapy for acne. PMID:23015740

Biodegradation of malathion, α- and β-endosulfan by bacterial strains isolated from agricultural soil in Veracruz, Mexico.

PubMed

Jimenez-Torres, Catya; Ortiz, Irmene; San-Martin, Pablo; Hernandez-Herrera, R Idalia

2016-12-01

The objective of this study was to evaluate the capacity of two bacterial strains isolated, cultivated, and purified from agricultural soils of Veracruz, Mexico, for biodegradation and mineralisation of malathion (diethyl 2-(dimethoxyphosphorothioyl) succinate) and α- and β-endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6-9-methano-2,4,3-benzodioxathiepine-3-oxide). The isolated bacterial strains were identified using biochemical and morphological characterization and the analysis of their 16S rDNA gene, as Enterobacter cloacae strain PMM16 (E1) and E. amnigenus strain XGL214 (M1). The E1 strain was able to degrade endosulfan, whereas the M1 strain was capable of degrading both pesticides. The E1 strain degraded 71.32% of α-endosulfan and 100% of β-endosulfan within 24 days. The absence of metabolites, such as endosulfan sulfate, endosulfan lactone, or endosulfan diol, would suggest degradation of endosulfan isomers through non-oxidative pathways. Malathion was completely eliminated by the M1 strain. The major metabolite was butanedioic acid. There was a time-dependent increase in bacterial biomass, typical of bacterial growth, correlated with the decrease in pesticide concentration. The CO 2 production also increased significantly with the addition of pesticides to the bacterial growth media, demonstrating that, under aerobic conditions, the bacteria utilized endosulfan and malathion as a carbon source. Here, two bacterial strains are shown to metabolize two toxic pesticides into non-toxic intermediates.

Recovery of bioactive protein from bacterial inclusion bodies using trifluoroethanol as solubilization agent.

PubMed

Upadhyay, Vaibhav; Singh, Anupam; Jha, Divya; Singh, Akansha; Panda, Amulya K

2016-06-08

Formation of inclusion bodies poses a major hurdle in recovery of bioactive recombinant protein from Escherichia coli. Urea and guanidine hydrochloride have routinely been used to solubilize inclusion body proteins, but many times result in poor recovery of bioactive protein. High pH buffers, detergents and organic solvents like n-propanol have been successfully used as mild solubilization agents for high throughput recovery of bioactive protein from bacterial inclusion bodies. These mild solubilization agents preserve native-like secondary structures of proteins in inclusion body aggregates and result in improved recovery of bioactive protein as compared to conventional solubilization agents. Here we demonstrate solubilization of human growth hormone inclusion body aggregates using 30% trifluoroethanol in presence of 3 M urea and its refolding into bioactive form. Human growth hormone was expressed in E. coli M15 (pREP) cells in the form of inclusion bodies. Different concentrations of trifluoroethanol with or without addition of low concentration (3 M) of urea were used for solubilization of inclusion body aggregates. Thirty percent trifluoroethanol in combination with 3 M urea was found to be suitable for efficient solubilization of human growth hormone inclusion bodies. Solubilized protein was refolded by dilution and purified by anion exchange and size exclusion chromatography. Purified protein was analyzed for secondary and tertiary structure using different spectroscopic tools and was found to be bioactive by cell proliferation assay. To understand the mechanism of action of trifluoroethanol, secondary and tertiary structure of human growth hormone in trifluoroethanol was compared to that in presence of other denaturants like urea and guanidine hydrochloride. Trifluoroethanol was found to be stabilizing the secondary structure and destabilizing the tertiary structure of protein. Finally, it was observed that trifluoroethanol can be used to solubilize

Understanding the Mechanism of Bacterial Biofilms Resistance to Antimicrobial Agents

PubMed Central

Singh, Shriti; Singh, Santosh Kumar; Chowdhury, Indrajit; Singh, Rajesh

2017-01-01

A biofilm is a group of microorganisms, that causes health problems for the patients with indwelling medical devices via attachment of cells to the surface matrix. It increases the resistance of a microorganism for antimicrobial agents and developed the human infection. Current strategies are removed or prevent the microbial colonies from the medical devices, which are attached to the surfaces. This will improve the clinical outcomes in favor of the patients suffering from serious infectious diseases. Moreover, the identification and inhibition of genes, which have the major role in biofilm formation, could be the effective approach for health care systems. In a current review article, we are highlighting the biofilm matrix and molecular mechanism of antimicrobial resistance in bacterial biofilms. PMID:28553416

PHYLOGENETIC AFFILIATION OF WATER DISTRIBUTION SYSTEM BACTERIAL ISOLATES USING 16S RDNA SEQUENCE ANALYSIS

EPA Science Inventory

In a previously described study, only 15% of the bacterial strains isolated from a water distribution system (WDS) grown on R2A agar were identifiable using fatty acid methyl esthers (FAME) profiling. The lack of success was attributed to the use of fatty acid databases of bacter...

Comparison of commercial DNA extraction kits for isolation and purification of bacterial and eukaryotic DNA from PAH-contaminated soils.

PubMed

Mahmoudi, Nagissa; Slater, Greg F; Fulthorpe, Roberta R

2011-08-01

Molecular characterization of the microbial populations of soils and sediments contaminated with polycyclic aromatic hydrocarbons (PAHs) is often a first step in assessing intrinsic biodegradation potential. However, soils are problematic for molecular analysis owing to the presence of organic matter, such as humic acids. Furthermore, the presence of contaminants, such as PAHs, can cause further challenges to DNA extraction, quantification, and amplification. The goal of our study was to compare the effectiveness of four commercial soil DNA extraction kits (UltraClean Soil DNA Isolation kit, PowerSoil DNA Isolation kit, PowerMax Soil DNA Isolation kit, and FastDNA SPIN kit) to extract pure, high-quality bacterial and eukaryotic DNA from PAH-contaminated soils. Six different contaminated soils were used to determine if there were any biases among the kits due to soil properties or level of contamination. Extracted DNA was used as a template for bacterial 16S rDNA and eukaryotic 18S rDNA amplifications, and PCR products were subsequently analyzed using denaturing gel gradient electrophoresis (DGGE). We found that the FastDNA SPIN kit provided significantly higher DNA yields for all soils; however, it also resulted in the highest levels of humic acid contamination. Soil texture and organic carbon content of the soil did not affect the DNA yield of any kit. Moreover, a liquid-liquid extraction of the DNA extracts found no residual PAHs, indicating that all kits were effective at removing contaminants in the extraction process. Although the PowerSoil DNA Isolation kit gave relatively low DNA yields, it provided the highest quality DNA based on successful amplification of both bacterial and eukaryotic DNA for all six soils. DGGE fingerprints among the kits were dramatically different for both bacterial and eukaryotic DNA. The PowerSoil DNA Isolation kit revealed multiple bands for each soil and provided the most consistent DGGE profiles among replicates for both

Heavy Metal Detoxification by Different Bacillus Species Isolated from Solar Salterns

PubMed Central

Syed, Shameer; Chinthala, Paramageetham

2015-01-01

The biosorption mechanism is an alternative for chemical precipitation and ultrafiltration which have been employed to treat heavy metal contamination with a limited success. In the present study, three species of Bacillus which were isolated from solar salterns were screened for their detoxification potential of the heavy metals, lead, chromium, and copper, by biosorption. Biosorption potential of each isolate was determined by Atomic Absorption Spectroscopy (AAS), Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), and Energy Dispersive Spectroscopy (EDS) as the amount of metal present in the medium after the treatment with the isolates. Bacterial isolates, Bacillus licheniformis NSPA5, Bacillus cereus NSPA8, and Bacillus subtilis NSPA13, showed significant level of lead biosorption with maximum of 87–90% by Bacillus cereus NSPA8. The biosorption of copper and chromium was relatively low in comparison with lead. With the obtained results, we have concluded that the bacterial isolates are potential agents to treat metal contamination in more efficient and ecofriendly manner. PMID:26525498

Bacteria as growth-promoting agents for citrus rootstocks.

PubMed

Giassi, Valdionei; Kiritani, Camila; Kupper, Katia Cristina

2016-09-01

The microbial community plays an essential role in maintaining the ecological balance of soils. Interactions between microorganisms and plants have a major influence on the nutrition and health of the latter, and growth-promoting rhizobacteria can be used to improve plant development through a wide range of mechanisms. Therefore, the objective of the present study was to evaluate bacteria as growth-promoting agents for citrus rootstocks. A total of 30 bacterial isolates (11 of Bacillus spp., 11 actinobacteria, and 8 lactic acid bacteria) were evaluated in vitro for indoleacetic acid production, phosphate solubilization, and nitrogen (N) fixation. In vivo testing consisted of growth promotion trials of the bacterial isolates that yielded the best results on in vitro tests with three rootstocks: Swingle citrumelo [Citrus×paradisi Macfad cv. Duncan×Poncirus trifoliata (L.) Raf.], Sunki mandarin (Citrus sunki Hort. ex Tan), and rangpur (Citrus×limonia Osbeck). The parameters of interest were height, number of leaves, stem diameter, shoot and root dry mass, and total dry mass at 150days after germination. The results showed that most bacterial isolates were capable of IAA production. Only one lactic acid bacterium isolate (BL06) solubilized phosphate, with a high solubilization index (PSI>3). In the actinobacteria group, isolates ACT01 (PSI=2.09) and ACT07 (PSI=2.01) exhibited moderate phosphate-solubilizing properties. Of the Bacillus spp. isolates, only CPMO6 and BM17 solubilized phosphate. The bacterial isolates that most fixated nitrogen were BM17, ACT11, and BL24. In the present study, some bacteria were able to promote growth of citrus rootstocks; however, this response was dependent on plant genotype and isolate. Bacillus spp. BM16 and CPMO4 were able to promote growth of Swingle citrumelo. In Sunki mandarin plants, the best treatment results were obtained with BM17 (Bacillus sp.) and ACT11 (actinobacteria). For Rangpur lime rootstock, only BM05 (Bacillus sp

Carbaryl degradation by bacterial isolates from a soil ecosystem of the Gaza Strip

PubMed Central

Hamada, Mazen; Matar, Ammar; Bashir, Abdallah

2015-01-01

Abstract Carbaryl is an important and widely used insecticide that pollutes soil and water systems. Bacteria from the local soil ecosystem of the Gaza Strip capable of utilizing carbaryl as the sole source of carbon and nitrogen were isolated and identified as belonging to Bacillus, Morganella, Pseudomonas, Aeromonas and Corynebacterium genera. Carbaryl biodegradation by Bacillus, Morganella and Corynebacterium isolates was analyzed in minimal liquid media supplemented with carbaryl as the only source of carbon and nitrogen. Bacillus and Morganella exhibited 94.6% and 87.3% carbaryl degradation, respectively, while Corynebacterium showed only moderate carbaryl degradation at 48.8%. These results indicate that bacterial isolates from a local soil ecosystem in the Gaza Strip are able to degrade carbaryl and can be used to decrease the risk of environmental contamination by this insecticide. PMID:26691466

[Microorganism test systems and antibiograms useful for the proper use of antibacterial agents].

PubMed

Takahashi, Shunji

2010-07-01

Antimicrobial agents are used for the accurate diagnosis of infectious diseases and effective implementation of antibacterial chemotherapy. The role of microbiological technologists is to provide data from microorganism tests useful for rapid infection treatment. Gram strain can be used to observe microorganisms and neutrophils from specimens of a patient. It is also possible to estimate the kinds of microorganism. If bacterial infectious disease is negative, there is no need for antibacterial chemotherapy. The applied dose of antibacterial agents is different in every hospital. Also, there is a difference in the percentage antibacterial agent susceptibility of isolates. Antibiograms must be created to investigate local factors. For empiric therapy, antibiograms are useful when choosing antibacterial agents showing marked efficacy against the clinical isolate. Microorganism test systems which are useful for the proper use of antibacterial agents are necessary to facilitate safe antibacterial chemotherapy and prevent the development of resistant bacteria. We report a microorganism test system employed at the Sapporo City General Hospital.

Whole-Genome Sequences of Two Borrelia afzelii and Two Borrelia garinii Lyme Disease Agent Isolates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Casjens, S.R.; Dunn, J.; Mongodin, E. F.

2011-12-01

Human Lyme disease is commonly caused by several species of spirochetes in the Borrelia genus. In Eurasia these species are largely Borrelia afzelii, B. garinii, B. burgdorferi, and B. bavariensis sp. nov. Whole-genome sequencing is an excellent tool for investigating and understanding the influence of bacterial diversity on the pathogenesis and etiology of Lyme disease. We report here the whole-genome sequences of four isolates from two of the Borrelia species that cause human Lyme disease, B. afzelii isolates ACA-1 and PKo and B. garinii isolates PBr and Far04.

[Timing of bacterial colonization in severe burns: is strict isolation necessary?].

PubMed

Barret, Juan P

2003-12-01

Infection is still one of the main causes of mortality in severe burn patients. Strict isolation has been used for the prevention of infection, but the efficacy of this measure is debatable. The aim of this study was to determine the timing of bacterial colonization in these patients and to ascertain whether strict isolation is indicated. Thirty consecutive children with severe burns were studied. Patients were only barrier-nursed during dressing changes. On admission and twice weekly over the entire hospital stay, burn, sputum, gastric aspirates, feces, and blood samples were obtained for culture. All isolates were tested for specific biotypes. Results were studied with linear regression and repeated measures ANOVA to determine the timing of colonization and cross-colonization between patients. On admission, normal cutaneous flora were isolated from burn cultures of all patients. The remaining cultures were negative. After one week, gastric aspirates were found to be colonized by gram-negative bacteria and fungi. This was followed by colonization of feces, burn, and sputum cultures. Biotype identification showed unidirectional colonization from the gastrointestinal tract to burns and upper airway. There were no cross infections between patients. Microbial colonization in severe burn patients was endogenous in nature and there were no cross infections. Thus, strict isolation is not necessary in burn centers, except during outbreaks of multi-resistant microorganisms.

Two similar but atypical strains of coryneform group A-4 isolated from patients with endophthalmitis.

PubMed Central

Coudron, P E; Harris, R C; Vaughan, M G; Dalton, H P

1985-01-01

Corynebacterium species and other coryneform organisms isolated from clinical specimens are frequently considered contaminants. We isolated two strains of a gram-positive organism from the vitreous fluid of two patients with endophthalmitis who had previously received intraocular lens transplants. The biochemical characteristics and gas chromatographic patterns of both isolates were similar to those of coryneform group A-4 strains. Major differences included esculin hydrolysis, nitrate reduction, growth pigment, and lactic acid production. These two strains along with a limited number of strains collected at the Special Bacterial Pathogens Laboratory (Division of Bacterial Diseases, Centers for Disease Control, Atlanta, Ga.) may represent a subgroup of coryneform group A-4. Results of in vitro susceptibility testing performed with antimicrobial agents commonly used to treat patients with bacterial endophthalmitis underscore the importance of determining MBCs for slow-growing organisms. This report cautions microbiologists not to discard organisms frequently considered contaminants when isolated from body fluids that are normally sterile and from patients receiving local steroids. PMID:3935657

Pilot Screening to Determine Antimicrobial Synergies in a Multidrug-Resistant Bacterial Strain Library

PubMed Central

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

Increased detection of mastitis pathogens by real-time PCR compared to bacterial culture.

PubMed

Keane, O M; Budd, K E; Flynn, J; McCoy, F

2013-09-21

Rapid and accurate identification of mastitis pathogens is important for disease control. Bacterial culture and isolate identification is considered the gold standard in mastitis diagnosis but is time consuming and results in many culture-negative samples. Identification of mastitis pathogens by PCR has been proposed as a fast and sensitive alternative to bacterial culture. The results of bacterial culture and PCR for the identification of the aetiological agent of clinical mastitis were compared. The pathogen identified by traditional culture methods was also detected by PCR in 98 per cent of cases indicating good agreement between the positive results of bacterial culture and PCR. A mastitis pathogen could not be recovered from approximately 30 per cent of samples by bacterial culture, however, an aetiological agent was identified by PCR in 79 per cent of these samples. Therefore, a mastitis pathogen was detected in significantly more milk samples by PCR than by bacterial culture (92 per cent and 70 per cent, respectively) although the clinical relevance of PCR-positive culture-negative results remains controversial. A mixed infection of two or more mastitis pathogens was also detected more commonly by PCR. Culture-negative samples due to undetected Staphylococcus aureus infections were rare. The use of PCR technology may assist in rapid mastitis diagnosis, however, accurate interpretation of PCR results in the absence of bacterial culture remains problematic.

Isolation, experimental transmission, and characterization of causative agent of Potomac horse fever.

PubMed

Holland, C J; Ristic, M; Cole, A I; Johnson, P; Baker, G; Goetz, T

1985-02-01

Potomac horse fever, a disease characterized by fever, anorexia, leukopenia, and occasional diarrhea, is fatal in approximately 30 percent of affected animals. The seasonal occurrence of the disease (June to October) and evidence of antibodies to the rickettsia Ehrlichia sennetsu in the serum of convalescing horses suggested that a related rickettsia might be the causative agent. Such an agent was isolated in cultured blood monocytes from an experimentally infected pony. This intracytoplasmic organism was adapted to growth in primary cultures of canine blood monocytes. A healthy pony inoculated with these infected monocytes also developed the disease. The organism was reisolated from this animal which, at autopsy, had pathological manifestations typical of Potomac horse fever. Cross serologic reactions between the newly isolated agent and antisera to 15 rickettsiae revealed that it is related to certain members of the genus Ehrlichia, particularly to Ehrlichia sennetsu. Since the disease occurs in other parts of the United States as well as in the vicinity of the Potomac River, and since it has also been reported in Europe, the name equine monocytic ehrlichiosis is proposed as being more descriptive.

Antimicrobial susceptibility survey on bacterial agents of canine and feline urinary tract infections: Weight of the empirical treatment.

PubMed

Rampacci, Elisa; Bottinelli, Marco; Stefanetti, Valentina; Hyatt, Doreene R; Sgariglia, Elisa; Coletti, Mauro; Passamonti, Fabrizio

2018-06-01

This work characterised the antimicrobial susceptibility of uropathogens isolated from empirically treated dogs and cats. Within-household transmission of uropathogens can involve humans and companion animals. Knowledge on the prevalence and susceptibility pattern of isolates from canine and feline urine samples and the impact of prior antimicrobial treatment is important to prevent the dissemination of antimicrobial resistance. A retrospective study was conducted selecting antibiotic-treated companion animals. Urine samples were collected by cystocentesis and were submitted to an Italian diagnostic laboratory over a 2-year period (2013-2015). The antimicrobial susceptibility of the isolates was analysed both using Clinical and Laboratory Standards Institute (CLSI) guidelines and a formula to help select rational antimicrobial therapy. Gram-negative bacteria were clearly prevalent. Gentamicin had the highest impact factors. Amoxicillin/clavulanic acid and doxycycline appeared to be the most effective compounds against Gram-positive infections, whilst marbofloxacin may be a useful option against Gram-negative urinary tract infections (UTIs) as well as doxycycline and trimethoprim/sulfamethoxazole in cats and dogs, respectively. Consulting published studies, a comparable overall trend regarding bacterial species incriminated in canine and feline UTIs and their susceptibilities seems likely, despite different circumstances where the studies were conducted. Companion animals are potential reservoirs of drug-resistant uropathogens. Judicious use of antibiotics is necessary to maintain the efficacy of antimicrobials in human and veterinary medicine. Antimicrobial susceptibility monitoring programmes are therefore essential to facilitate the choice of antimicrobial agent that is most likely to be effective, particularly in cases of prior antimicrobial treatment. Copyright © 2018 International Society for Chemotherapy of Infection and Cancer. All rights reserved.

Occurrence and antibacterial susceptibility pattern of bacterial pathogens isolated from diarrheal patients in Pakistan.

PubMed

Rasool, Muhammad H; Siddique, Abu B; Saqalein, Muhammad; Asghar, Muhammad J; Zahoor, Muhammad A; Aslam, Bilal; Shafiq, Humerah B; Nisar, Muhammad A

2016-03-01

To determine the occurrence of bacterial pathogens responsible for diarrhea and to engender information regarding the effectiveness of commonly used antibiotic against diarrhea. This cross-sectional study was conducted between April and July 2014. Samples were collected from the Divisional Headquarter and Allied Hospital, Faisalabad, Pakistan. The differential and selective media were used to isolate bacterial pathogens, which were identified through cultural characteristics, microscopy, and biochemical tests. Disc diffusion assay was carried out using Muller Hinton agar medium, and minimum inhibitory concentration was determined using broth dilution method against isolated pathogens. One hundred and forty-one (100%) samples were positive for some bacteria. Frequency of occurrence was Bacillus cereus (B. cereus) (66%), Escherichia coli (E.coli) (48.5%), Salmonella typhi (S. Typhi) (27.7%), Pseudomonas aeruginosa (P. aeruginosa) (8.5%), and Staphylococcus aureus (S. aureus) (4.3%). Single pathogen was detected in 20 (14.2%) samples whereas combinations were found in 121 (85.8%) samples. Bacillus cereus and E.coli were the most frequently detected pathogens followed by the S. Typhi, P. aeruginosa, and Staph. aureus. The percentage occurrence of isolated pathogens was 31% in B. cereus, 31% in E. coli, 18% in S. Typhi, 5% in P. aeruginosa, and 3% in Staph. aureus. Pseudomonas aeruginosa showed resistance against Amoxicillin and Cefotaxime, whereas S. aureus was found resistant against Cefotaxime. Statistical analysis using one way Analysis of Variance revealed that Ofloxacin and Gentamicin had significant (p less than 0.05) differences against all isolates as compared with other antibiotics used in this study.

Genetic diversity of the causative agent of ice-ice disease of the seaweed Kappaphycus alvarezii from Karimunjawa island, Indonesia

NASA Astrophysics Data System (ADS)

Syafitri, E.; Prayitno, S. B.; Ma'ruf, W. F.; Radjasa, O. K.

2017-02-01

An essential step in investigating the bacterial role in the occurrence of diseases in Kappaphycus alvarezii is the characterization of bacteria associated with this seaweed. A molecular characterization was conducted on the genetic diversity of the causative agents of ice-ice disease associated with K. alvarezii widely known as the main source of kappa carrageenan. K. alvrezii infected with ice-ice were collected from the Karimunjawa island, North Java Sea, Indonesia. Using Zobell 2216E marine agar medium, nine bacterial species were isolated from the infected seaweed. The molecular characterizations revealed that the isolated bacteria causing ice-ice disease were closely related to the genera of Alteromonas, Bacillus, Pseudomonas, Pseudoalteromonas, Glaciecola, Aurantimonas, and Rhodococcus. In order to identify the symptoms causative organisms, the isolated bacterial species were cultured and were evaluated for their pathogenity. Out of 9 species, only 3 isolates were able to cause the ice-ice symptoms and consisted of Alteromonas macleodii, Pseudoalteromonas issachenkonii and Aurantimonas coralicida. A. macleodii showed the highest pathogenity.

Isolation of bacterial strains able to metabolize lignin and lignin-related compounds.

PubMed

Tian, J-H; Pourcher, A-M; Peu, P

2016-07-01

In this study, we identified five strains isolated from soil and sediments able to degrade kraft lignin, aromatic dyes and lignin derivatives. Using 16S rRNA gene sequencing, the isolates were identified as Serratia sp. JHT01, Serratia liquefacien PT01, Pseudomonas chlororaphis PT02, Stenotrophomonas maltophilia PT03 and Mesorhizobium sp. PT04. All the isolates showed significant growth on lignin with no water-extractable compounds. Synthetic aromatic dyes were used to assess the presence of oxidative enzymes. All the isolates were able to use the thiazine dye Methylene blue and the anthraquinone dye Remazol Brilliant Blue R as the sole carbon source. Guaiacol, veratryl alcohol and biphenyl were also mineralized by all the strains isolated. These results suggest they could be used for the treatment of aromatic pollutants and for the degradation of the lignocellulosic biomass. The valorization of waste lignin and lignocellulosic biomass by biocatalysis opens up new possibilities for the production of value-added substituted aromatics, biofuel and for the treatment of aromatic pollutants. Bacteria with ligninolytic potential could be a source of novel enzymes for controlled lignin depolymerization. In this work, five soil bacteria were isolated and studied. Every isolate showed significant growth on lignin and was able to degrade several lignin monomers and ligninolytic indicator dyes. They could thus be a source of novel ligninolytic enzymes as well as candidates for a bacterial consortium for the delignification of lignocellulosic biomass. © 2016 The Society for Applied Microbiology.

Bacterial succession during curing process of a skate (Dipturus batis) and isolation of novel strains.

PubMed

Reynisson, E; Thornór Marteinsson, V; Jónsdóttir, R; Magnússon, S H; Hreggvidsson, G O

2012-08-01

To study the succession of cultivated and uncultivated microbes during the traditional curing process of skate. The microbial diversity was evaluated by sequencing 16Sr RNA clone libraries and cultivation in variety of media from skate samples taken periodically during a 9-day curing process. A pH shift was observed (pH 6·64-9·27) with increasing trimethylamine (2·6 up to 75·6 mg N per 100 g) and total volatile nitrogen (TVN) (from 58·5 to 705·8 mg N per 100 g) but with relatively slow bacterial growth. Uncured skate was dominated by Oceanisphaera and Pseudoalteromonas genera but was substituted after curing by Photobacterium and Aliivibrio in the flesh and Pseudomonas on the skin. Almost 50% of the clone library is derived from putative undiscovered species. Cultivation and enrichment strategies resulted in isolation of putatively new species belonging to the genera Idiomarina, Rheinheimera, Oceanisphaera, Providencia and Pseudomonas. The most abundant genera able to hydrolyse urea to ammonia were Oceanisphaera, Psychrobacter, Pseudoalteromonas and isolates within the Pseudomonas genus. The curing process of skate is controlled and achieved by a dynamic bacterial community where the key players belong to Oceanisphaera, Pseudoalteromonas, Photobacterium, Aliivibrio and Pseudomonas. For the first time, the bacterial population developments in the curing process of skate are presented and demonstrate a reservoir of many yet undiscovered bacterial species. No Claim to Norwegian Government works Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.

Genetic Diversity of Bacterial Communities and Gene Transfer Agents in Northern South China Sea

PubMed Central

Sun, Fu-Lin; Wang, You-Shao; Wu, Mei-Lin; Jiang, Zhao-Yu; Sun, Cui-Ci; Cheng, Hao

2014-01-01

Pyrosequencing of the 16S ribosomal RNA gene (rDNA) amplicons was performed to investigate the unique distribution of bacterial communities in northern South China Sea (nSCS) and evaluate community structure and spatial differences of bacterial diversity. Cyanobacteria, Proteobacteria, Actinobacteria, and Bacteroidetes constitute the majority of bacteria. The taxonomic description of bacterial communities revealed that more Chroococcales, SAR11 clade, Acidimicrobiales, Rhodobacterales, and Flavobacteriales are present in the nSCS waters than other bacterial groups. Rhodobacterales were less abundant in tropical water (nSCS) than in temperate and cold waters. Furthermore, the diversity of Rhodobacterales based on the gene transfer agent (GTA) major capsid gene (g5) was investigated. Four g5 gene clone libraries were constructed from samples representing different regions and yielded diverse sequences. Fourteen g5 clusters could be identified among 197 nSCS clones. These clusters were also related to known g5 sequences derived from genome-sequenced Rhodobacterales. The composition of g5 sequences in surface water varied with the g5 sequences in the sampling sites; this result indicated that the Rhodobacterales population could be highly diverse in nSCS. Phylogenetic tree analysis result indicated distinguishable diversity patterns among tropical (nSCS), temperate, and cold waters, thereby supporting the niche adaptation of specific Rhodobacterales members in unique environments. PMID:25364820

Development of practical diagnostic methods for monitoring rice bacterial panicle blight disease and evaluation of rice germplasm for resistance

USDA-ARS?s Scientific Manuscript database

A study was initiated to understand Burkholderia glumae, the major causal agent for bacterial panicle blight disease of rice; to develop practical diagnostic methods for monitoring the disease; and to evaluate rice germplasm for resistance. Burkholderia glumae was frequently isolated from infected p...

Development of practical diagnostic methods for monitoring rice bacterial panicle blight disease and evaluation of rice germplasm for resistance

USDA-ARS?s Scientific Manuscript database

A study was initiated to understand Burkholderia glumae (major causal agent for bacterial panicle blight disease of rice) to develop practical diagnostic methods for monitoring the disease; and to evaluate rice germplasm for resistance. B. glumae was frequently isolated from symptomatic panicles on...

Bacterial Contamination of Boar Semen and its Relationship to Sperm Quality Preserved in Commercial Extender Containing Gentamicin Sulfate.

PubMed

Gączarzewicz, D; Udała, J; Piasecka, M; Błaszczyk, B; Stankiewicz, T

2016-09-01

This study was designed to determine the degree and type of bacterial contamination in boar semen (79 ejaculates from Large White and Landrace boars) and its consequences for sperm quality during storage (27 extended semen samples, 16°C for five days) under practical conditions of artificial insemination (AI). The results revealed the presence of aerobic bacteria in 99% of the ejaculates (from 80 to 370 ×106 colony-forming units/mL). Most of the ejaculates contained two or three bacterial contaminants, while the Staphylococcus, Streptococcus, and Pseudomonas bacterial genera were most frequently isolated. Also detected were Enterobacter spp., Bacillus spp., Proteus spp., Escherichia coli, P. fluorescens, and P. aeruginosa. In general, the growth of certain bacterial types isolated prior to semen processing (Enterobacter spp., E. coli, P. fluorescens, and P. aeruginosa) was not discovered on different days of storage, but fluctuations (with a tendency towards increases) were found in the frequencies of Bacillus spp., Pseudomonas spp., and Staphylococcus spp. isolates up to the end of storage. Semen preserved for five days exhibited decreases in sperm motility and increases in the average number of total aerobic bacteria; this was associated with sperm agglutination, plasma membrane disruption, and acrosome damage. We inferred that, due to the different degrees and types of bacterial contaminants in the boar ejaculates, the inhibitory activity of some antimicrobial agents used in swine extenders (such as gentamicin sulfate) may be limited. Because such agents can contribute to the overgrowth of certain aerobic bacteria and a reduction in the quality of stored semen, procedures with high standards of hygiene and microbiological control should be used when processing boar semen.

Initial nitrogen enrichment conditions determines variations in nitrogen substrate utilization by heterotrophic bacterial isolates.

PubMed

Ghosh, Suchismita; Ayayee, Paul A; Valverde-Barrantes, Oscar J; Blackwood, Christopher B; Royer, Todd V; Leff, Laura G

2017-04-04

The nitrogen (N) cycle consists of complex microbe-mediated transformations driven by a variety of factors, including diversity and concentrations of N compounds. In this study, we examined taxonomic diversity and N substrate utilization by heterotrophic bacteria isolated from streams under complex and simple N-enrichment conditions. Diversity estimates differed among isolates from the enrichments, but no significant composition were detected. Substrate utilization and substrate range of bacterial assemblages differed within and among enrichments types, and not simply between simple and complex N-enrichments. N substrate use patterns differed between isolates from some complex and simple N-enrichments while others were unexpectedly similar. Taxonomic composition of isolates did not differ among enrichments and was unrelated to N use suggesting strong functional redundancy. Ultimately, our results imply that the available N pool influences physiology and selects for bacteria with various abilities that are unrelated to their taxonomic affiliation.

Glycerol Monolaurate Inhibits Lipase Production by Clinical Ocular Isolates Without Affecting Bacterial Cell Viability.

PubMed

Flanagan, Judith Louise; Khandekar, Neeta; Zhu, Hua; Watanabe, Keizo; Markoulli, Maria; Flanagan, John Terence; Papas, Eric

2016-02-01

We sought to determine the relative lipase production of a range of ocular bacterial isolates and to assess the efficacy of glycerol monolaurate (GML) in inhibiting this lipase production in high lipase-producing bacteria without affecting bacterial cell growth. Staphylococcus aureus,Staphylococcus epidermidis,Propionibacterium acnes, and Corynebacterium spp. were inoculated at a density of 10(6)/mL in varying concentrations of GML up to 25 μg/mL for 24 hours at 37 °C with constant shaking. Bacterial suspensions were centrifuged, bacterial cell density was determined, and production of bacterial lipase was quantified using a commercial lipase assay kit. Staphylococcus spp. produced high levels of lipase activity compared with P. acnes and Corynebacterium spp. GML inhibited lipase production by Staphylococcal spp. in a dose-dependent manner, with S. epidermidis lipase production consistently more sensitive to GML than S. aureus. Glycerol monolaurate showed significant (P < 0.05) lipase inhibition above concentrations of 15 μg/mL in S. aureus and was not cytotoxic up to 25 μg/mL. For S. epidermidis, GML showed significant (P < 0.05) lipase inhibition above 7.5 μg/mL. Lipase activity varied between species and between strains. Staphylococcal spp. produced higher lipase activity compared with P. acnes and Corynebacterium spp. Glycerol monolaurate inhibited lipase production by S. aureus and S. epidermidis at concentrations that did not adversely affect bacterial cell growth. GML can be used to inhibit ocular bacterial lipase production without proving detrimental to commensal bacteria viability.

Carbon nanotubes as anti-bacterial agents.

PubMed

Mocan, Teodora; Matea, Cristian T; Pop, Teodora; Mosteanu, Ofelia; Buzoianu, Anca Dana; Suciu, Soimita; Puia, Cosmin; Zdrehus, Claudiu; Iancu, Cornel; Mocan, Lucian

2017-10-01

Multidrug-resistant bacterial infections that have evolved via natural selection have increased alarmingly at a global level. Thus, there is a strong need for the development of novel antibiotics for the treatment of these infections. Functionalized carbon nanotubes through their unique properties hold great promise in the fight against multidrug-resistant bacterial infections. This new family of nanovectors for therapeutic delivery proved to be innovative and efficient for the transport and cellular translocation of therapeutic molecules. The current review examines the latest progress in the antibacterial activity of carbon nanotubes and their composites.

Characterization of CCN and IN activity of bacterial isolates collected in Atlanta, GA

NASA Astrophysics Data System (ADS)

Purdue, Sara; Waters, Samantha; Karthikeyan, Smruthi; Konstantinidis, Kostas; Nenes, Athanasios

2016-04-01

Characterization of CCN activity of bacteria, other than a few select types such as Pseudomonas syringae, is limited, especially when looked at in conjunction with corresponding IN activity. The link between these two points is especially important for bacteria as those that have high CCN activity are likely to form an aqueous phase required for immersion freezing. Given the high ice nucleation temperature of bacterial cells, especially in immersion mode, it is important to characterize the CCN and IN activity of many different bacterial strains. To this effect, we developed a droplet freezing assay (DFA) which consists of an aluminum cold plate, cooled by a continuous flow of an ethylene glycol-water mixture, in order to observe immersion freezing of the collected bacteria. Here, we present the initial results on the CCN and IN activities of bacterial samples we have collected in Atlanta, GA. Bacterial strains were collected and isolated from rainwater samples taken from different storms throughout the year. We then characterized the CCN activity of each strain using a DMT Continuous Flow Streamwise Thermal Gradient CCN Counter by exposing the aerosolized bacteria to supersaturations ranging from 0.05% to 0.6%. Additionally, using our new DFA, we characterized the IN activity of each bacterial strain at temperatures ranging from -20oC to 0oC. The combined CCN and IN activity gives us valuable information on how some uncharacterized bacteria contribute to warm and mixed-phase cloud formation in the atmosphere.

Multicenter Evaluation of the Bruker MALDI Biotyper CA System for the Identification of Clinical Aerobic Gram-Negative Bacterial Isolates

PubMed Central

Faron, Matthew L.; Buchan, Blake W.; Hyke, Josh; Madisen, Neil; Lillie, Jennifer L.; Granato, Paul A.; Wilson, Deborah A.; Procop, Gary W.; Novak-Weekley, Susan; Marlowe, Elizabeth; Cumpio, Joven; Griego-Fullbright, Christen; Kindig, Sandra; Timm, Karen; Young, Stephen; Ledeboer, Nathan A.

2015-01-01

The prompt and accurate identification of bacterial pathogens is fundamental to patient health and outcome. Recent advances in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) have revolutionized bacterial identification in the clinical laboratory, but uniform incorporation of this technology in the U.S. market has been delayed by a lack of FDA-cleared systems. In this study, we conducted a multicenter evaluation of the MALDI Biotyper CA (MBT-CA) System (Bruker Daltonics Inc, Billerica, MA) for the identification of aerobic gram-negative bacteria as part of a 510(k) submission to the FDA. A total of 2,263 aerobic gram negative bacterial isolates were tested representing 23 genera and 61 species. Isolates were collected from various clinical sources and results obtained from the MBT-CA System were compared to DNA sequencing and/or biochemical testing. Isolates that failed to report as a "high confidence species ID" [log(score) ≥2.00] were re-tested using an extraction method. The MBT-CA System identified 96.8% and 3.1% of isolates with either a "high confidence" or a "low confidence" [log(score) value between 1.70 and <2.00] species ID, respectively. Two isolates did not produce acceptable confidence scores after extraction. The MBT-CA System correctly identified 99.8% (2,258/2,263) to genus and 98.2% (2,222/2,263) to species level. These data demonstrate that the MBT-CA System provides accurate results for the identification of aerobic gram-negative bacteria. PMID:26529504

Multicenter Evaluation of the Bruker MALDI Biotyper CA System for the Identification of Clinical Aerobic Gram-Negative Bacterial Isolates.

PubMed

Faron, Matthew L; Buchan, Blake W; Hyke, Josh; Madisen, Neil; Lillie, Jennifer L; Granato, Paul A; Wilson, Deborah A; Procop, Gary W; Novak-Weekley, Susan; Marlowe, Elizabeth; Cumpio, Joven; Griego-Fullbright, Christen; Kindig, Sandra; Timm, Karen; Young, Stephen; Ledeboer, Nathan A

2015-01-01

The prompt and accurate identification of bacterial pathogens is fundamental to patient health and outcome. Recent advances in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) have revolutionized bacterial identification in the clinical laboratory, but uniform incorporation of this technology in the U.S. market has been delayed by a lack of FDA-cleared systems. In this study, we conducted a multicenter evaluation of the MALDI Biotyper CA (MBT-CA) System (Bruker Daltonics Inc, Billerica, MA) for the identification of aerobic gram-negative bacteria as part of a 510(k) submission to the FDA. A total of 2,263 aerobic gram negative bacterial isolates were tested representing 23 genera and 61 species. Isolates were collected from various clinical sources and results obtained from the MBT-CA System were compared to DNA sequencing and/or biochemical testing. Isolates that failed to report as a "high confidence species ID" [log(score) ≥2.00] were re-tested using an extraction method. The MBT-CA System identified 96.8% and 3.1% of isolates with either a "high confidence" or a "low confidence" [log(score) value between 1.70 and <2.00] species ID, respectively. Two isolates did not produce acceptable confidence scores after extraction. The MBT-CA System correctly identified 99.8% (2,258/2,263) to genus and 98.2% (2,222/2,263) to species level. These data demonstrate that the MBT-CA System provides accurate results for the identification of aerobic gram-negative bacteria.

The Potency of Local Bacterial Isolates Encapsulated Within Sodium Alginate in Carbofuran Degradation

NASA Astrophysics Data System (ADS)

Priyani, Nunuk; Pratiwi, Dian; Suryanto, Dwi

2018-03-01

Research on the viability of bacteria encapsulated within sodium alginate and their potential in carbofuran degradation has been done. A total of 8 bacterial isolates have been isolated from slaughter house waste. A 100 ml of Bushnell-Hass Broth (BHB) medium containing 146.982 ppm of carbofuran was used as a medium. As much as 2 gr of beads which equal to 108cells.ml‑1 was inoculated into each medium culture and incubated for 15 days at ambient temperature and was shaken at 100 rpm. Analysis of carbofuran residues using High Performance Liquid Chromatography (HPLC) showed that the best 2 isolates, DN 1 and OR 2, were able to decrease carbofuran phenol concentration up to 30.37 % and 32.09% respectively compared to control. These results suggested that no significant different from the ability of free cell which decreased carbofuran phenol concentration up to 32.54% and 28.29%.

Pederin-type pathways of uncultivated bacterial symbionts: analysis of o-methyltransferases and generation of a biosynthetic hybrid.

PubMed

Zimmermann, Katrin; Engeser, Marianne; Blunt, John W; Munro, Murray H G; Piel, Jörn

2009-03-04

The complex polyketide pederin is a potent antitumor agent isolated from Paederus spp. rove beetles. We have previously isolated a set of genes from a bacterial endosymbiont that are good candidates for pederin biosynthesis. To biochemically study this pathway, we expressed three methyltransferases from the putative pederin pathway and used the partially unmethylated analogue mycalamide A from the marine sponge Mycale hentscheli as test substrate. Analysis by high-resolution MS/MS and NMR revealed that PedO regiospecifically methylates the marine compound to generate the nonnatural hybrid compound 18-O-methylmycalamide A with increased cytotoxicity. To our knowledge, this is the first biochemical evidence that invertebrates can obtain defensive complex polyketides from bacterial symbionts.

Value of multiplex PCR to determine the bacterial and viral aetiology of pneumonia in school-age children.

PubMed

Aydemir, Yusuf; Aydemir, Özlem; Pekcan, Sevgi; Özdemir, Mehmet

2017-02-01

Conventional methods for the aetiological diagnosis of community-acquired pneumonia (CAP) are often insufficient owing to low sensitivity and the long wait for the results of culture and particularly serology, and it often these methods establish a diagnosis in only half of cases. To evaluate the most common bacterial and viral agents in CAP using a fast responsive PCR method and investigate the relationship between clinical/laboratory features and aetiology, thereby contributing to empirical antibiotic selection and reduction of treatment failure. In children aged 4-15 years consecutively admitted with a diagnosis of CAP, the 10 most commonly detected bacterial and 12 most commonly detected viral agents were investigated by induced sputum using bacterial culture and multiplex PCR methods. Clinical and laboratory features were compared between bacterial and viral pneumonia. In 78 patients, at least one virus was detected in 38 (48.7%) and at least one bacterium in 32 (41%). In addition, both bacteria and viruses were detected in 16 (20.5%) patients. Overall, the agent detection rate was 69.2%. The most common viruses were respiratory syncytial virus and influenza and the most frequently detected bacteria were S. pneumoniae and H. influenzae. PCR was superior to culture for bacterial isolation (41% vs 13%, respectively). Fever, wheezing and radiological features were not helpful in differentiating between bacterial and viral CAP. White blood cell count, CRP and ESR values were significantly higher in the bacterial/mixed aetiology group than in the viral aetiology group. In CAP, multiplex PCR is highly reliable, superior in detecting multiple pathogens and rapidly identifies aetiological agents. Clinical features are poor for differentiation between bacterial and viral infections. The use of PCR methods allow physicians to provide more appropriate antimicrobial therapy, resulting in a better response to treatment, and it may be possible for use as a routine service

Whole-Genome Sequencing and Concordance Between Antimicrobial Susceptibility Genotypes and Phenotypes of Bacterial Isolates Associated with Bovine Respiratory Disease

PubMed Central

Owen, Joseph R.; Noyes, Noelle; Young, Amy E.; Prince, Daniel J.; Blanchard, Patricia C.; Lehenbauer, Terry W.; Aly, Sharif S.; Davis, Jessica H.; O’Rourke, Sean M.; Abdo, Zaid; Belk, Keith; Miller, Michael R.; Morley, Paul; Van Eenennaam, Alison L.

2017-01-01

Extended laboratory culture and antimicrobial susceptibility testing timelines hinder rapid species identification and susceptibility profiling of bacterial pathogens associated with bovine respiratory disease, the most prevalent cause of cattle mortality in the United States. Whole-genome sequencing offers a culture-independent alternative to current bacterial identification methods, but requires a library of bacterial reference genomes for comparison. To contribute new bacterial genome assemblies and evaluate genetic diversity and variation in antimicrobial resistance genotypes, whole-genome sequencing was performed on bovine respiratory disease–associated bacterial isolates (Histophilus somni, Mycoplasma bovis, Mannheimia haemolytica, and Pasteurella multocida) from dairy and beef cattle. One hundred genomically distinct assemblies were added to the NCBI database, doubling the available genomic sequences for these four species. Computer-based methods identified 11 predicted antimicrobial resistance genes in three species, with none being detected in M. bovis. While computer-based analysis can identify antibiotic resistance genes within whole-genome sequences (genotype), it may not predict the actual antimicrobial resistance observed in a living organism (phenotype). Antimicrobial susceptibility testing on 64 H. somni, M. haemolytica, and P. multocida isolates had an overall concordance rate between genotype and phenotypic resistance to the associated class of antimicrobials of 72.7% (P < 0.001), showing substantial discordance. Concordance rates varied greatly among different antimicrobial, antibiotic resistance gene, and bacterial species combinations. This suggests that antimicrobial susceptibility phenotypes are needed to complement genomically predicted antibiotic resistance gene genotypes to better understand how the presence of antibiotic resistance genes within a given bacterial species could potentially impact optimal bovine respiratory disease

Aetiological agents of vaginitis in Nigerian women.

PubMed

Otuonye, N M; Odunukwe, N N; Idigbe, E O; Imosemi, O D; Smith, S I; Chigbo, R C; Bamidele, M; Oparaugo, C T; Mafe, A G; Musa, A Z

2004-01-01

This study focuses on the identification of aetiological agents of vaginitis in Nigerian women. Study subjects are drawn from patients presenting with lower abdominal pain, vaginal discharge and itching at the gynaecology clinic of Lagos University Teaching Hospital and at the Clinical Centre of the Nigerian Institute of Medical Research, Yaba, Lagos, between January 2001 and July 2002. A total of 250 patients gave informed consent to participate in the study. The patients also had pre- and post-test human immunodeficiency virus (HIV) counselling. Each patient completed a questionnaire in order to provide biographical data, past clinical history and socio-economic background information. A cervical swab (CS) and a high-vaginal swab (HVS) were obtained from each patient. Swab samples were examined for pH and under light microscopy by Gram's stain and as wet preparations in 10% potassium hydroxide. Subsequently, samples were cultured on appropriate media at optimal conditions and a drug sensitivity profile for all isolates was determined by standard methods. Blood samples were screened and confirmed for HIV antibodies. Bacterial, fungal and parasitic pathogens were identified or isolated in samples from 241 (96.4%) of the women. Bacterial agents (Neisseria, Streptococcus and Staphylococcus species) were predominant in 128 (51.2%) patients, followed by fungi in 108 (43.2%) and parasites (Trichomonas vaginalis) in five (2.0%). Sensitivity to ciprofloxacin was seen in 40% of Staphylococcus species and in 90% of Neisseria species. Positive HIV serology was seen in 25 (10%) of the 250 women studied, 20 (80%) of which had concurrent microbial infections. Overall, a broad spectrum of microbial agents were shown to be responsible for vaginitis in the group of patients studied.

Gamma-irradiated bacterial preparation having anti-tumor activity

DOEpatents

Vass, Arpad A.; Tyndall, Richard L.; Terzaghi-Howe, Peggy

1999-01-01

A bacterial preparation from Pseudomonas species isolated #15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

Identification of Heterotrophic Zinc Mobilization Processes among Bacterial Strains Isolated from Wheat Rhizosphere (Triticum aestivum L.).

PubMed

Costerousse, Benjamin; Schönholzer-Mauclaire, Laurie; Frossard, Emmanuel; Thonar, Cécile

2018-01-01

Soil and plant inoculation with heterotrophic zinc-solubilizing bacteria (ZSB) is considered a promising approach for increasing zinc (Zn) phytoavailability and enhancing crop growth and nutritional quality. Nevertheless, it is necessary to understand the underlying bacterial solubilization processes to predict their repeatability in inoculation strategies. Acidification via gluconic acid production remains the most reported process. In this study, wheat rhizosphere soil serial dilutions were plated on several solid microbiological media supplemented with scarcely soluble Zn oxide (ZnO), and 115 putative Zn-solubilizing isolates were directly detected based on the formation of solubilization halos around the colonies. Eight strains were selected based on their Zn solubilization efficiency and siderophore production capacity. These included one strain of Curtobacterium , two of Plantibacter , three strains of Pseudomonas , one of Stenotrophomonas , and one strain of Streptomyces In ZnO liquid solubilization assays, the presence of glucose clearly stimulated organic acid production, leading to medium acidification and ZnO solubilization. While solubilization by Streptomyces and Curtobacterium was attributed to the accumulated production of six and seven different organic acids, respectively, the other strains solubilized Zn via gluconic, malonic, and oxalic acids exclusively. In contrast, in the absence of glucose, ZnO dissolution resulted from proton extrusion (e.g., via ammonia consumption by Plantibacter strains) and complexation processes (i.e., complexation with glutamic acid in cultures of Curtobacterium ). Therefore, while gluconic acid production was described as a major Zn solubilization mechanism in the literature, this study goes beyond and shows that solubilization mechanisms vary among ZSB and are strongly affected by growth conditions. IMPORTANCE Barriers toward a better understanding of the mechanisms underlying zinc (Zn) solubilization by bacteria

[Isolation of the causative agent and histopathology of athlete's foot (preliminary report)].

PubMed

Pelayo Ulacia, S; Dafhnis, D

1980-01-01

Given the incidence of athlete's foot in our environment a study of the causing agent as well as the lesions it determines is made. For that purpose four male patients from an ESBEC (High School in the Countryside), seen at Jovellanos Municipality Hospital in the dermatology section, were studied. Average age was 13. The authors conducted a tissular study with adjusting sampling for isolating the relevant causing agent. The authors showed that the infecting agents were Trichophyton mentagrophytes and Trichophyton rubrum which determined hyperkeratosis with marked and focal parakeratosis; maceration areas with destruction and sphacelus of the corneal layer, a site with abundant necrotic cells and spores; acanthosis; papillomatosis; hyphas, and a lympho-histocytary inflammatory infiltrate in the upper dermis.

Characteristics of environmental isolates of Legionella pneumophila. [Legionella

DOE Office of Scientific and Technical Information (OSTI.GOV)

Orrison, L.H.; Cherry, W.B.; Fliermans, C.B.

1981-07-01

Thirty-eight cultures of Legionella pneumophila isolated from survace waters were characterized by their morphological, tinctorial, biochemical, and serological properties and by their ability to produce disease in guinea pigs. Their susceptibility to antimicrobial agents also was tested. When they were compared with clinical isolates, no important differences were found between cultures from the two sources. Sodium hippurate hydrolysis, gelatin liquefaction, pigment formation, and ..beta..-lactamase and alkaline phosphatase activity were useful in differentiating the four described species of Legionella. Hydrolysis of diacetylfluorescein and the inability to reduce nitrate help to distinguish Legionella species from other gram-negative bacterial rods.

Prevalence of bacterial pathogens and their anti-microbial resistance in Tilapia and their pond water in Trinidad.

PubMed

Newaj-Fyzul, A; Mutani, A; Ramsubhag, A; Adesiyun, A

2008-05-01

In Trinidad, Tilapia (Oreonchromis spp.) is one of the most important fresh water food fish and the number of farms has been increasing annually. A study was conducted in the local tilapia industry to determine the microbial quality of pond water, prevalence of bacterial pathogens and their anti-microbial resistance using the disk diffusion method. Seventy-five apparently healthy fish and 15 pond water samples from three of the four commercial tilapia fish farms in the country were processed. The 202 bacterial isolates recovered from fish slurry and 88 from water, belonged to 13 and 16 genera respectively. The predominant bacteria from fish slurry were Pseudomonas spp. (60.0%), Aeromonas spp. (44.0%), Plesiomonas (41.3%) and Chromobacterium (36.0%) (P < 0.05; chi(2)) compared with isolates from pond water where Bacillus spp. (80.0%), Staphylococcus spp., Alcaligenes spp. and Aeromonas spp. (60.0%) were most prevalent (P < 0.05; chi(2)). Using eight anti-microbial agents, to test bacteria from five genera (Aeromonas, Chromobacterium, Enterobacter, Plesiomonas and Pseudomonas), 168 (97.1%) of 173 bacterial isolates from fish slurry exhibited resistance to one or more anti-microbial agents compared with 47 (90.4%) of 52 from water (P > 0.05; chi(2)). Resistance was high to ampicillin, 90.2% (158 of 173), erythromycin, 66.5% (115 of 173) and oxytetracycline, 52.6%, (91 of 173) but relatively low to chloramphenicol, 9.8% (17 of 173) and sulphamethoxazole/trimethoprim, 6.4% (11 of 173) (P < 0.05; chi(2)). For pond water isolates, the frequency of resistance across bacterial genera ranged from 75% (nine of 12) for Chromobacter spp. to 100% found amongst Enterobacter spp. (six of six), Plesiomonas spp. (nine of nine) and Pseudomonas spp. (eight of eight) (P < 0.05; chi(2)). Resistance was generally high to ampicillin, 78.8% (41 of 52), erythromycin, 51.9% (27 of 52) and oxytetracycline, 34.5% (18 of 52) but low to sulphamethoxazole/trimethoprim, 7.7% (four of 52) and

Treatment of bacterial meningitis: an update.

PubMed

Shin, Seon Hee; Kim, Kwang Sik

2012-10-01

The introduction of protein conjugate vaccines for Haemophilus influenzae type b (Hib), Streptococcus pneumoniae (S. pneumoniae) and Neisseria meningitidis (N. menigitidis) has changed the epidemiology of bacterial meningitis. Bacterial meningitis continues to be an important cause of mortality and morbidity, and our incomplete knowledge of its pathogenesis and emergence of antimicrobial resistant bacteria contribute to such mortality and morbidity. An early empiric antibiotic treatment is critical for the management of patients with bacterial meningitis. This article gives an overview on optimal treatment strategies of bacterial meningitis, along with considerations of new insights on epidemiology, clinical and laboratory findings supportive of bacterial meningitis, chemoprophylaxis, selection of initial antimicrobial agents for suspected bacterial meningitis, antimicrobial resistance and utility of new antibiotics, status on anti-inflammatory agents and adjunctive therapy, and pathogenesis of bacterial meningitis. Prompt treatment of bacterial meningitis with an appropriate antibiotic is essential. Optimal antimicrobial treatment of bacterial meningitis requires bactericidal agents able to penetrate the blood-brain barrier (BBB), with efficacy in cerebrospinal fluid (CSF). Several new antibiotics have been introduced for the treatment of meningitis caused by resistant bacteria, but their use in human studies has been limited. More complete understanding of the microbial and host interactions that are involved in the pathogenesis of bacterial meningitis and associated neurologic sequelae is likely to help in developing new strategies for the prevention and therapy of bacterial meningitis.

[Susceptibility surveillance of clinical isolates to fluoroquinolone antimicrobial agents from 2003 to 2008: post-marketing study of prulifloxacin].

PubMed

Kawai, Shin; Yoshida, Atsushi; Okazaki, Mitsuhiro; Tsujihara, Yoshito; Inuzuka, Kazuhisa; Takeuchi, Kazuhide; Yamashita, Naoko; Onodera, Makoto; Hiraishi, Toru; Ida, Takashi; Maebashi, Kazunori

2010-06-01

Yearly changes in the susceptibility of clinical isolates to ulifloxacin (UFX) and other fluoroquinolones were examined through surveys over 3 periods. In the first survey, 534 strains derived from 19 species were collected from clinical specimens during 6 months from December 2003 to May 2004. In the same way, 805 strains were collected from December 2005 to May 2006 in the second survey, and 863 strains were from December 2007 to May 2008 in the third survey. Over these 3 study periods, the susceptibilities of fluoroquinolones against methicillin-susceptible Staphylococcus aureus and Escherichia coli were decreased. The isolation frequency of levofloxacin-nonsusceptible strain was increased from 0% to 11.8% and from 14.6% to 20.8%, respectively. MIC90s of UFX against these pathogens were also increased, but its MIC90 for E. coli was 2 to 4 times lower than that of levofloxacin. On the other hand, the susceptibility of strains of Klebsiella pneumoniae to UFX was increased. Among the fluoroquinolones tested, UFX showed the most potent activity against Pseudomonas aeruginosa, and no changes in the MIC90s occurred during the surveillance. Although one strain of Streptococcus pneumoniae isolated in the third study period showed levofloxacin-resistance (MIC, 8 microg/mL), there were nearly no changes in the MIC90s of any agents tested including UFX against S. pneumoniae during the surveillance. As for other bacterial species, a tendency to increase in resistance to UFX was not observed. The activity of UFX against Salmonella spp. and Shigella spp. was superior/equal to those of fluoroquinolones tested.

Gamma-irradiated bacterial preparation having anti-tumor activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vass, A.A.; Tyndall, R.L.; Terzaghi-Howe, P.

1999-11-16

This application describes a bacterial preparation from Pseudomonas species isolated {number{underscore}sign}15 ATCC 55638 that has been exposed to gamma radiation exhibits cytotoxicity that is specific for neoplastic carcinoma cells. A method for obtaining a bacterial preparation having antitumor activity consists of suspending a bacterial isolate in media and exposing the suspension to gamma radiation. A bacterial preparation of an aged culture of an amoeba-associated bacteria exhibits anti-reverse transcriptase activity. A method for obtaining a bacterial preparation having anti-reverse transcriptase activity from an amoeba-associated bacterial isolate grown to stationary phase is disclosed.

Bacterial Sialidase

NASA Technical Reports Server (NTRS)

2004-01-01

Data shows that elevated sialidase in bacterial vaginosis patients correlates to premature births in women. Bacterial sialidase also plays a significant role in the unusual colonization of Pseudomonas aeruginosa in cystic fibrosis patients. Crystals of Salmonella sialidase have been reproduced and are used for studying the inhibitor-enzyme complexes. These inhibitors may also be used to inhibit a trans-sialidase of Trypanosome cruzi, a very similar enzyme to bacterial sialidase, therefore preventing T. cruzi infection, the causitive agent of Chagas' disease. The Center for Macromolecular Crystallography suggests that inhibitors of bacterial sialidases can be used as prophylactic drugs to prevent bacterial infections in these critical cases.

Gold Nanoparticles: An Efficient Antimicrobial Agent against Enteric Bacterial Human Pathogen

PubMed Central

Shamaila, Shahzadi; Zafar, Noshin; Riaz, Saira; Sharif, Rehana; Nazir, Jawad; Naseem, Shahzad

2016-01-01

Enteric bacterial human pathogens, i.e., Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Klebsiella pneumoniae, are the major cause of diarrheal infections in children and adults. Their structure badly affects the human immune system. It is important to explore new antibacterial agents instead of antibiotics for treatment. This project is an attempt to explain how gold nanoparticles affect these bacteria. We investigated the important role of the mean particle size, and the inhibition of a bacterium is dose-dependent. Ultra Violet (UV)-visible spectroscopy revealed the size of chemically synthesized gold nanoparticle as 6–40 nm. Atomic force microscopy (AFM) analysis confirmed the size and X-ray diffractometry (XRD) analysis determined the polycrystalline nature of gold nanoparticles. The present findings explained how gold nanoparticles lyse Gram-negative and Gram-positive bacteria. PMID:28335198

Whole-Genome Sequencing and Concordance Between Antimicrobial Susceptibility Genotypes and Phenotypes of Bacterial Isolates Associated with Bovine Respiratory Disease.

PubMed

Owen, Joseph R; Noyes, Noelle; Young, Amy E; Prince, Daniel J; Blanchard, Patricia C; Lehenbauer, Terry W; Aly, Sharif S; Davis, Jessica H; O'Rourke, Sean M; Abdo, Zaid; Belk, Keith; Miller, Michael R; Morley, Paul; Van Eenennaam, Alison L

2017-09-07

Extended laboratory culture and antimicrobial susceptibility testing timelines hinder rapid species identification and susceptibility profiling of bacterial pathogens associated with bovine respiratory disease, the most prevalent cause of cattle mortality in the United States. Whole-genome sequencing offers a culture-independent alternative to current bacterial identification methods, but requires a library of bacterial reference genomes for comparison. To contribute new bacterial genome assemblies and evaluate genetic diversity and variation in antimicrobial resistance genotypes, whole-genome sequencing was performed on bovine respiratory disease-associated bacterial isolates ( Histophilus somni , Mycoplasma bovis , Mannheimia haemolytica , and Pasteurella multocida ) from dairy and beef cattle. One hundred genomically distinct assemblies were added to the NCBI database, doubling the available genomic sequences for these four species. Computer-based methods identified 11 predicted antimicrobial resistance genes in three species, with none being detected in M. bovis While computer-based analysis can identify antibiotic resistance genes within whole-genome sequences (genotype), it may not predict the actual antimicrobial resistance observed in a living organism (phenotype). Antimicrobial susceptibility testing on 64 H. somni , M. haemolytica , and P. multocida isolates had an overall concordance rate between genotype and phenotypic resistance to the associated class of antimicrobials of 72.7% ( P < 0.001), showing substantial discordance. Concordance rates varied greatly among different antimicrobial, antibiotic resistance gene, and bacterial species combinations. This suggests that antimicrobial susceptibility phenotypes are needed to complement genomically predicted antibiotic resistance gene genotypes to better understand how the presence of antibiotic resistance genes within a given bacterial species could potentially impact optimal bovine respiratory disease

Bacteria isolated from bats inhibit the growth of Pseudogymnoascus destructans, the causative agent of white-nose syndrome.

PubMed

Hoyt, Joseph R; Cheng, Tina L; Langwig, Kate E; Hee, Mallory M; Frick, Winifred F; Kilpatrick, A Marm

2015-01-01

Emerging infectious diseases are a key threat to wildlife. Several fungal skin pathogens have recently emerged and caused widespread mortality in several vertebrate groups, including amphibians, bats, rattlesnakes and humans. White-nose syndrome, caused by the fungal skin pathogen Pseudogymnoascus destructans, threatens several hibernating bat species with extinction and there are few effective treatment strategies. The skin microbiome is increasingly understood to play a large role in determining disease outcome. We isolated bacteria from the skin of four bat species, and co-cultured these isolates with P. destructans to identify bacteria that might inhibit or kill P. destructans. We then conducted two reciprocal challenge experiments in vitro with six bacterial isolates (all in the genus Pseudomonas) to quantify the effect of these bacteria on the growth of P. destructans. All six Pseudomonas isolates significantly inhibited growth of P. destructans compared to non-inhibitory control bacteria, and two isolates performed significantly better than others in suppressing P. destructans growth for at least 35 days. In both challenge experiments, the extent of suppression of P. destructans growth was dependent on the initial concentration of P. destructans and the initial concentration of the bacterial isolate. These results show that bacteria found naturally occurring on bats can inhibit the growth of P. destructans in vitro and should be studied further as a possible probiotic to protect bats from white-nose syndrome. In addition, the presence of these bacteria may influence disease outcomes among individuals, populations, and species.

Bacteria Isolated from Bats Inhibit the Growth of Pseudogymnoascus destructans, the Causative Agent of White-Nose Syndrome

PubMed Central

Hoyt, Joseph R.; Cheng, Tina L.; Langwig, Kate E.; Hee, Mallory M.; Frick, Winifred F.; Kilpatrick, A. Marm

2015-01-01

Emerging infectious diseases are a key threat to wildlife. Several fungal skin pathogens have recently emerged and caused widespread mortality in several vertebrate groups, including amphibians, bats, rattlesnakes and humans. White-nose syndrome, caused by the fungal skin pathogen Pseudogymnoascus destructans, threatens several hibernating bat species with extinction and there are few effective treatment strategies. The skin microbiome is increasingly understood to play a large role in determining disease outcome. We isolated bacteria from the skin of four bat species, and co-cultured these isolates with P. destructans to identify bacteria that might inhibit or kill P. destructans. We then conducted two reciprocal challenge experiments in vitro with six bacterial isolates (all in the genus Pseudomonas) to quantify the effect of these bacteria on the growth of P. destructans. All six Pseudomonas isolates significantly inhibited growth of P. destructans compared to non-inhibitory control bacteria, and two isolates performed significantly better than others in suppressing P. destructans growth for at least 35 days. In both challenge experiments, the extent of suppression of P. destructans growth was dependent on the initial concentration of P. destructans and the initial concentration of the bacterial isolate. These results show that bacteria found naturally occurring on bats can inhibit the growth of P. destructans in vitro and should be studied further as a possible probiotic to protect bats from white-nose syndrome. In addition, the presence of these bacteria may influence disease outcomes among individuals, populations, and species. PMID:25853558

Vitellogenin from the silkworm, Bombyx mori: an effective anti-bacterial agent.

PubMed

Singh, Nitin Kumar; Pakkianathan, Britto Cathrin; Kumar, Manish; Prasad, Tulika; Kannan, Mani; König, Simone; Krishnan, Muthukalingan

2013-01-01

Silkworm, Bombyx mori, vitellogenin (Vg) was isolated from perivisceral fat body of day 3 of pupa. Both Vg subunits were co-purified as verified by mass spectrometry and immunoblot. Purified Vg responded to specific tests for major posttranslational modifications on native gels indicating its nature as lipo-glyco-phosphoprotein. The Vg fraction had strong antibacterial activity against Gram negative bacterium Escherichia coli and Gram positive bacterium Bacillus subtilis. Microscopic images showed binding of Vg to bacterial cells and their destruction. When infected silkworm larvae were treated with purified Vg they survived the full life cycle in contrast to untreated animals. This result showed that Vg has the ability to inhibit the proliferation of bacteria in the silkworm fluid system without disturbing the regular metabolism of the host.

In vitro antifungal susceptibility to six antifungal agents of 229 Candida isolates from patients with diabetes mellitus.

PubMed

Manfredi, M; McCullough, M J; Polonelli, L; Conti, S; Al-Karaawi, Z M; Vescovi, P; Porter, S R

2006-06-01

The most common antifungal drugs in current clinical use for the treatment of oral candidosis are polyenes and azoles, mainly used topically. Poor glycaemic control in association with other local factors, such as the presence of oral dental prostheses, salivary pH, salivary flow rate and tobacco habits, may lead to the development of oral candidosis. Topical antifungal agents are frequently used to prevent the development of candidal infections in patients with poor metabolic control, particularly in the elderly wearing dentures. The aim of this study was to assess the antifungal susceptibility of Candida isolates to six antifungal agents using a commercially available kit, Fungitest. The isolated were collected from patients affected by diabetes mellitus from two different geographic localities (London, UK, and Parma, Italy) and from a group of healthy non-diabetic subjects. No differences in antifungal susceptibility to the six agents tested were observed between Candida isolates from diabetic and non-diabetic subjects. However, differences were observed between the two geographically different diabetes mellitus populations. Oral yeast isolates from diabetes mellitus patients in the UK more often displayed resistance or intermediate resistance to fluconazole (P=0.02), miconazole (P<0.0001), and ketoconazole (P=0.01) than did isolates from diabetes mellitus patients in Italy. In addition, more C. albicans isolates were found in diabetic and non-diabetic subjects that were susceptible to fluconazole (P=0.0008 and P=0.01, respectively) than non-albicans isolates. The difference in the antifungal resistance of isolates from the two populations of diabetes mellitus patients may be related to differences in the therapeutic management of candidal infections between the two centres.

In vitro susceptibility of gram-negative bacterial isolates to chlorhexidine gluconate.

PubMed

Mengistu, Y; Erge, W; Bellete, B

1999-05-01

To investigate the susceptibility of clinical isolates of gram-negative bacteria to chlorhexidine gluconate. Prospective laboratory study. Tikur Anbessa Hospital, Addis Ababa, Ethiopia. Clinical specimens from 443 hospital patients. Significant number of gram negative bacteria were not inhibited by chlorhexidine gluconate (0.02-0.05%) used for antisepsis. Four hundred and forty three strains of gram-negative bacteria were isolated from Tikur Anbessa Hospital patients. Escherichia coli (31.6%) and Klebsiella pneumoniae (23%) were the most frequently isolated bacteria followed by Proteus species (13.3%), Pseudomonas species (9.2%), and Citrobacter species (6.1%). Each organism was tested to chlorhexidine gluconate (CHG), minimum inhibitory concentration (MIC) ranging from 0.0001% to 1%w/v. All Salmonella species and E. coli were inhibited by CHG, MIC < or = 0.01%. Twenty nine per cent of Acinetobacter, 28% of K. pneumoniae and Enterobacter species and 19-25% of Pseudomonas, Proteus and Providencia species were only inhibited at high concentrations of CHG (> or = 0.1%). Our results showed that a significant number of the gram-negative bacterial isolates were not inhibited by CHG at the concentration used for disinfection of wounds or instruments (MIC 0.02-0.05% w/v). It is therefore important to select appropriate concentration of this disinfectant and rationally use it for disinfection and hospital hygiene. Continuing follow up and surveillance is also needed to detect resistant bacteria to chlorhexidine or other disinfectants in time.

Survival and persistence of nonspore-forming biothreat agents in water.

PubMed

Gilbert, S E; Rose, L J

2012-09-01

To determine whether nonspore-forming biothreat agents can survive and persist in potable water that does not contain a disinfectant.  Autoclaved, de-chlorinated Atlanta municipal water was inoculated with eight isolates of bacterial biothreat agents (10⁶ CFU ml⁻¹). The inoculated water samples were incubated at 5, 8 (Francisella tularensis only) or 25°C and assayed for viability by culture and by the presence of metabolic activity as measured by esterase activity (ScanRDI, AES Chemunex). Viability as determined by culture varied from 1 to 30 days, depending upon the organism and the temperature of the water. All organisms were determined viable as measured by esterase activity for the entire 30 days, regardless of the incubation temperature.  Francisella tularensis was culturable for at least 21 days if held at 8°C. The remaining nonspore-forming bacterial biothreat agents were found to be metabolically active for at least 30 days in water held at 5 or 25°C.  The data can assist public health officials to determine the safety of drinking water after contamination with a biothreat agent. No claim to US Government works. Letters in Applied Microbiology © 2012 The Society for Applied Microbiology.

Degradation and depolymerization of plastic waste by local bacterial isolates and bubble column reactor

NASA Astrophysics Data System (ADS)

Hussein, Amal A.; Alzuhairi, Mohammed; Aljanabi, Noor H.

2018-05-01

Accumulation of plastics, especially Polyethylene terephthalate (PET), is an ever increasing ecological threat due to its excessive usage in everyday human life. Nowadays, there are many methods to get rid of plastic wastes including burning, recycling and burying. However, these methods are not very active since their long period, anaerobic conditions that increase the rate of toxic materials released into the environment. This work aims to study the biological degradation of PET microorganism isolated from soil sample. Thirty eight (38) bacterial isolates were isolated from ten soil and plastic waste sample collected from four different waste disposal sites in Baghdad city during different periods between December 2016 and March 2017. Isolation was performed using enrichment culture method (flasks method) by culturing the soil samples in flasks with MSM medium where there is no carbon source only PET. Results showed that Al-Za'farania sample gave a higher number of isolates (13 isolates), while other samples gave less number of isolates. Screening was performed depending on their ability to grow in liquid MSM which contains PET powder and pieces and change the color of the PET-emulsified liquid medium as well as their ability to form the clear zone on PET-MSM agar. The results showed that NH-D-1 isolate has the higher ability to degrade DPET and PET pieces. According to morphological, biochemical characterization and Vitek-2 technique, the most active isolate was identified as Acinetobacter baumannii.

Diversity, Bacterial Symbionts and Antibacterial Potential of Gut-Associated Fungi Isolated from the Pantala flavescens Larvae in China

PubMed Central

Shao, Ming-Wei; Lu, Yi-Hui; Miao, Shuang; Zhang, Yun; Chen, Ting-Ting; Zhang, Ying-Lao

2015-01-01

The diversity of fungi associated with the gut of Pantala flavescens larvae was investigated using a culture-dependent method and molecular identification based on an analysis of the internally transcribed spacer sequence. In total, 48 fungal isolates were obtained from P. flavescens larvae. Based on phylogenetic analyses, the fungal isolates were grouped in 5 classes and 12 different genera. Fourteen bacterial 16S rDNA sequences derived from total genomic DNA extractions of fungal mycelia were obtained. The majority of the sequences were associated with Proteobacteria (13/14), and one Bacillaceae (1/14) was included. Leclercia sp., Oceanobacillus oncorhynchi and Methylobacterium extorquens, were reported for the first time as bacterial endosymbionts in fungi. High-performance liquid chromatography (HPLC) analysis indicated that bacterial symbionts produced specific metabolites and also exerted an inhibitory effect on fungal metabolites. The biological activity of the fungal culture extracts against the pathogenic bacteria Staphylococcus aureus (ATCC 6538), Bacillus subtilis (ATCC 6633) and Escherichia coli (ATCC 8739) was investigated, and 20 extracts (42%) exhibited antibacterial activity against at least one of the tested bacterial strains. This study is the first report on the diversity and antibacterial activity of symbiotic fungi residing in the gut of P. flavescens larvae, and the results show that these fungi are highly diverse and could be exploited as a potential source of bioactive compounds. PMID:26221957

Diversity, Bacterial Symbionts and Antibacterial Potential of Gut-Associated Fungi Isolated from the Pantala flavescens Larvae in China.

PubMed

Shao, Ming-Wei; Lu, Yi-Hui; Miao, Shuang; Zhang, Yun; Chen, Ting-Ting; Zhang, Ying-Lao

2015-01-01

The diversity of fungi associated with the gut of Pantala flavescens larvae was investigated using a culture-dependent method and molecular identification based on an analysis of the internally transcribed spacer sequence. In total, 48 fungal isolates were obtained from P. flavescens larvae. Based on phylogenetic analyses, the fungal isolates were grouped in 5 classes and 12 different genera. Fourteen bacterial 16S rDNA sequences derived from total genomic DNA extractions of fungal mycelia were obtained. The majority of the sequences were associated with Proteobacteria (13/14), and one Bacillaceae (1/14) was included. Leclercia sp., Oceanobacillus oncorhynchi and Methylobacterium extorquens, were reported for the first time as bacterial endosymbionts in fungi. High-performance liquid chromatography (HPLC) analysis indicated that bacterial symbionts produced specific metabolites and also exerted an inhibitory effect on fungal metabolites. The biological activity of the fungal culture extracts against the pathogenic bacteria Staphylococcus aureus (ATCC 6538), Bacillus subtilis (ATCC 6633) and Escherichia coli (ATCC 8739) was investigated, and 20 extracts (42%) exhibited antibacterial activity against at least one of the tested bacterial strains. This study is the first report on the diversity and antibacterial activity of symbiotic fungi residing in the gut of P. flavescens larvae, and the results show that these fungi are highly diverse and could be exploited as a potential source of bioactive compounds.

In Vitro Activity of Delafloxacin against Contemporary Bacterial Pathogens from the United States and Europe, 2014

PubMed Central

Pfaller, M. A.; Sader, H. S.; Rhomberg, P. R.

2017-01-01

ABSTRACT The in vitro activities of delafloxacin and comparator antimicrobial agents against 6,485 bacterial isolates collected from medical centers in Europe and the United States in 2014 were tested. Delafloxacin was the most potent agent tested against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus, Streptococcus pneumoniae, viridans group streptococci, and beta-hemolytic streptococci and had activity similar to that of ciprofloxacin and levofloxacin against certain members of the Enterobacteriaceae. Overall, the broadest coverage of the tested pathogens (Gram-positive cocci and Gram-negative bacilli) was observed with meropenem and tigecycline in both Europe and the United States. Delafloxacin was shown to be active against organisms that may be encountered in acute bacterial skin and skin structure infections, respiratory infections, and urinary tract infections. PMID:28167542

In Vitro Activity of Delafloxacin against Contemporary Bacterial Pathogens from the United States and Europe, 2014.

PubMed

Pfaller, M A; Sader, H S; Rhomberg, P R; Flamm, R K

2017-04-01

The in vitro activities of delafloxacin and comparator antimicrobial agents against 6,485 bacterial isolates collected from medical centers in Europe and the United States in 2014 were tested. Delafloxacin was the most potent agent tested against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus , Streptococcus pneumoniae , viridans group streptococci, and beta-hemolytic streptococci and had activity similar to that of ciprofloxacin and levofloxacin against certain members of the Enterobacteriaceae Overall, the broadest coverage of the tested pathogens (Gram-positive cocci and Gram-negative bacilli) was observed with meropenem and tigecycline in both Europe and the United States. Delafloxacin was shown to be active against organisms that may be encountered in acute bacterial skin and skin structure infections, respiratory infections, and urinary tract infections. Copyright © 2017 Pfaller et al.

Antibiotic resistance profile of bacterial isolates from animal farming aquatic environments and meats in a peri-urban community in Daejeon, Korea.

PubMed

Rho, Hyunjin; Shin, Bongjin; Lee, Okbok; Choi, Yu-Hyun; Rho, Jaerang; Lee, Jiyoung

2012-05-01

The increasing usage of antibiotics in the animal farming industry is an emerging worldwide problem contributing to the development of antibiotic resistance. The purpose of this work was to investigate the prevalence and antibiotic resistance profile of bacterial isolates collected from animal farming aquatic environments and meats in a peri-urban community in Daejeon, Korea. In an antibacterial susceptibility test, the bacterial isolates showed a high incidence of resistance (∼26.04%) to cefazolin, tetracycline, gentamycin, norfloxacin, erythromycin and vancomycin. The results from a test for multiple antibiotic resistance indicated that the isolates were displaying an approximately 5-fold increase in the incidence of multiple antibiotic resistance to combinations of two different antibiotics compared to combinations of three or more antibiotics. Most of the isolates showed multi-antibiotic resistance, and the resistance patterns were similar among the sampling groups. Sequencing data analysis of 16S rRNA showed that most of the resistant isolates appeared to be dominated by the classes Betaproteobacteria and Gammaproteobacteria, including the genera Delftia, Burkholderia, Escherichia, Enterobacter, Acinetobacter, Shigella and Pseudomonas.

Resistance to antimicrobial agents among Salmonella isolates recovered from layer farms and eggs in the Caribbean region.

PubMed

Adesiyun, Abiodun; Webb, Lloyd; Musai, Lisa; Louison, Bowen; Joseph, George; Stewart-Johnson, Alva; Samlal, Sannandan; Rodrigo, Shelly

2014-12-01

This investigation determined the frequency of resistance of 84 isolates of Salmonella comprising 14 serotypes recovered from layer farms in three Caribbean countries (Trinidad and Tobago, Grenada, and St. Lucia) to eight antimicrobial agents, using the disc diffusion method. Resistance among isolates of Salmonella was related to the country of recovery, type of sample, size of layer farms, and isolate serotype. Overall, all (100.0%) of the isolates exhibited resistance to one or more of seven antimicrobial agents tested, and all were susceptible to chloramphenicol. The resistance detected ranged from 11.9% to sulphamethoxazole-trimethoprim (SXT) to 100.0% to erythromycin. The difference was, however, not statistically significant (P = 0.23). Across countries, for types of samples that yielded Salmonella, significant differences in frequency of resistance were detected only to SXT (P = 0.002) in Trinidad and Tobago and to gentamycin (P = 0.027) in St. Lucia. For the three countries, the frequency of resistance to antimicrobial agents was significantly different for ampicillin (P = 0.001) and SXT (P = 0.032). A total of 83 (98.8%) of the 84 isolates exhibited 39 multidrug resistance patterns. Farm size significantly (P = 0.032) affected the frequency of resistance to kanamycin across the countries. Overall, among the 14 serotypes of Salmonella tested, significant (P < 0.05) differences in frequency of resistance were detected to kanamycin, ampicillin, and SXT. Results suggest that the relatively high frequency of resistance to six of the antimicrobial agents (erythromycin, streptomycin, gentamycin, kanamycin, ampicillin, and tetracycline) tested and the multidrug resistance detected may pose prophylactic and therapeutic concerns for chicken layer farms in the three countries studied.

Imipenem-resistant Gram-negative bacterial isolates carried by persons upon medical examination in Korea.

PubMed

Kim, So Yeon; Shin, Sang Yop; Rhee, Ji-Young; Ko, Kwan Soo

2017-08-01

Carbapenem-resistant Gram-negative bacteria (CR-GNB) have emerged and disseminated worldwide, become a great concern worldwide including Korea. The prevalence of fecal carriage of imipenem-resistant Gram-negative bacteria (IR-GNB) in persons in Korea was investigated. Stool samples were collected from 300 persons upon medical examination. Samples were screened for IR-GNB by using MacConkey agar with 2 μl/ml imipenem. Species were identified by 16S rRNA gene sequence analysis, and antimicrobial susceptibility was determined by the broth microdilution method. In total, 82 IR-GNB bacterial isolates were obtained from 79 (26.3%) out of 300 healthy persons. Multilocus sequence typing analysis showed very high diversity among IR P. aeruginosa, S. maltophilia, and E. cloacae isolates, and pulsed-field gel electrophoresis revealed five main pulsotypes of IR P. mirabilis. As for the presence of metallo-β-lactamases (MBLs), only one IMP-25-producing S. marcescens isolate was identified. Although only one carbapenemase-producing isolate was identified, the high colonization rates with IR-GNB isolates in this study is notable because carriers may be a reservoir for the dissemination of resistant pathogens within the community as well as in health care institutions.

Inquiry-based examination of chemical disruption of bacterial biofilms.

PubMed

Redelman, Carly V; Hawkins, Misty A W; Drumwright, Franklin R; Ransdell, Beverly; Marrs, Kathleen; Anderson, Gregory G

2012-01-01

Inquiry-based instruction in the sciences has been demonstrated as a successful educational strategy to use for both high school and college science classrooms. As participants in the NSF Graduate STEM Fellows in K-12 Education (GK-12) Program, we were tasked with creating novel inquiry-based activities for high school classrooms. As a way to introduce microbiology, molecular biology, ecology, and human health to students, we created a laboratory activity involving formation of biofilms composed of environmental bacteria from pond water and investigation into the resistance of these biofilms to antimicrobial agents. Two high schools participated in this study in different ways. Pike High School biology and advanced environmental science classrooms obtained pond water samples and grew biofilms from the bacteria in the pond water on plastic plates. They also observed killing of these biofilms by common household antimicrobial agents. As a senior capstone project, students at Arsenal Technical High School built on these research findings by isolating two different bacterial strains from the pond water and demonstrating the stimulatory effect of ethanol on biofilms formed by isolated bacterial strains. These activities were successful at introducing complex biological topics to high school students in a unique and exciting way. The students scored significantly higher on postactivity surveys compared with preactivity surveys that measured microbiology knowledge and experimental design knowledge. Furthermore, these projects seemed to elicit an excitement for science in the students who participated. Copyright © 2012 Wiley Periodicals, Inc.

Isolation and characterization of a hydrocarbonoclastic bacterial enrichment from total petroleum hydrocarbon contaminated sediments: potential candidates for bioaugmentation in bio-based processes.

PubMed

Di Gregorio, Simona; Siracusa, Giovanna; Becarelli, Simone; Mariotti, Lorenzo; Gentini, Alessandro; Lorenzi, Roberto

2016-06-01

Seven hydrocarbonoclastic new bacterial isolates were isolated from dredged sediments of a river estuary in Italy. The sediments were contaminated by shipyard activities since decades, mainly ascribable to the exploitation of diesel oil as the fuel for recreational and commercial navigation of watercrafts. The bacterial isolates were able to utilize diesel oil as sole carbon source. Their metabolic capacities were evaluated by GC-MS analysis, with reference to the depletion of both the normal and branched alkanes, the nC18 fatty acid methyl ester and the unresolved complex mixture of organic compounds. They were taxonomically identified as different species of Stenotrophomonas and Pseudomonas spp. by the combination of amplified ribosomal DNA restriction analysis (ARDRA) and repetitive sequence-based PCR (REP-PCR) analysis. The metabolic activities of interest were analyzed both in relation to the single bacterial strains and to the combination of the latter as a multibacterial species system. After 6 days of incubation in mineral medium with diesel oil as sole carbon source, the Stenotrophomonas sp. M1 strain depleted 43-46 % of Cn-alkane from C28 up to C30, 70 % of the nC18 fatty acid methyl ester and the 46 % of the unresolved complex mixture of organic compounds. On the other hand, the Pseudomonas sp. NM1 strain depleted the 76 % of the nC18 fatty acid methyl ester, the 50 % of the unresolved complex mixture of organic compounds. The bacterial multispecies system was able to completely deplete Cn-alkane from C28 up to C30 and to deplete the 95 % of the unresolved complex mixture of organic compounds. The isolates, either as single strains and as a bacterial multispecies system, were proposed as candidates for bioaugmentation in bio-based processes for the decontamination of dredged sediments.

Isolation, screening and molecular identification of novel bacterial strain removing methylene blue from water solutions

NASA Astrophysics Data System (ADS)

Kilany, Mona

2017-11-01

The potentially deleterious effects of methylene blue (MB) on human health drove the interest in its removal promptly. Bioremediation is an effective and eco friendly for removing MB. Soil bacteria were isolated and examined for their potential to remove MB. The most potent bacterial candidate was characterized and identified using 16S rRNA sequence technique. The evolutionary history of the isolate was conducted by maximum likelihood method. Some physiochemical parameters were optimized for maximum decolorization. Decolorization mechanism and microbial toxicity study of MB (100 mg/l) and by-products were investigated. Participation of heat killed bacteria in color adsorption have been investigated too. The bacterial isolate was identified as Stenotrophomonas maltophilia strain Kilany_MB 16S ribosomal RNA gene with 99% sequence similarity. The sequence was submitted to NCBI (Accession number = KU533726). Phylogeny depicted the phylogenetic relationships between 16S ribosomal RNA gene, partial sequence (1442 bp), of the isolated strain and other strains related to Stenotrophomonas maltophilia in the GenBank database. The optimal conditions were investigated to be pH 5 at 30 °C, after 24 h using 5 mg/l MB showing optimum decolorization percentage (61.3%). Microbial toxicity study demonstrated relative reduction in the toxicity of MB decolorized products on test bacteria. Mechanism of color removal was proved by both biosorption and biodegradation, where heat-killed and live cells showed 43 and 52% of decolorization, respectively, as a maximum value after 24-h incubation. It was demonstrated that the mechanism of color removal is by adsorption. Therefore, good performance of S maltophilia in MB color removal reinforces the exploitation of these bacteria in environmental clean-up and restoration of the ecosystem.

Ionome changes in Xylella fastidiosa-infected Nicotiana tabacum correlate with virulence and discriminate between subspecies of bacterial isolates.

PubMed

Oliver, J E; Sefick, S A; Parker, J K; Arnold, T; Cobine, P A; De La Fuente, L

2014-10-01

Characterization of ionomes has been used to uncover the basis of nutrient utilization and environmental adaptation of plants. Here, ionomic profiles were used to understand the phenotypic response of a plant to infection by genetically diverse isolates of Xylella fastidiosa, a gram-negative, xylem-limited bacterial plant pathogen. In this study, X. fastidiosa isolates were used to infect a common model host (Nicotiana tabacum 'SR1'), and leaf and sap concentrations of eleven elements together with plant colonization and symptoms were assessed. Multivariate statistical analysis revealed that changes in the ionome were significantly correlated with symptom severity and bacterial populations in host petioles. Moreover, plant ionome modification by infection could be used to differentiate the X. fastidiosa subspecies with which the plant was infected. This report establishes host ionome modification as a phenotypic response to infection.

Optimization of isolation and cultivation of bacterial endophytes through addition of plant extract to nutrient media

PubMed Central

Eevers, N; Gielen, M; Sánchez-López, A; Jaspers, S; White, J C; Vangronsveld, J; Weyens, N

2015-01-01

Many endophytes have beneficial effects on plants and can be exploited in biotechnological applications. Studies hypothesize that only 0.001–1% of all plant-associated bacteria are cultivable. Moreover, even after successful isolations, many endophytic bacteria often show reduced regrowth capacity. This research aimed to optimize isolation processes and culturing these bacteria afterwards. We compared several minimal and complex media in a screening. Beside the media themselves, two gelling agents and adding plant extract to media were investigated to enhance the number and diversity of endophytes as well as the growth capacity when regrown after isolation. In this work, 869 medium delivered the highest numbers of cultivable bacteria, as well as the highest diversity. When comparing gelling agents, no differences were observed in the numbers of bacteria. Adding plant extract to the media lead to a slight increase in diversity. However, when adding plant extract to improve the regrowth capacity, sharp increases of viable bacteria occurred in both rich and minimal media. PMID:25997013

Tetrachloromethane-Degrading Bacterial Enrichment Cultures and Isolates from a Contaminated Aquifer.

PubMed

Penny, Christian; Gruffaz, Christelle; Nadalig, Thierry; Cauchie, Henry-Michel; Vuilleumier, Stéphane; Bringel, Françoise

2015-07-02

The prokaryotic community of a groundwater aquifer exposed to high concentrations of tetrachloromethane (CCl₄) for more than three decades was followed by terminal restriction fragment length polymorphism (T-RFLP) during pump-and-treat remediation at the contamination source. Bacterial enrichments and isolates were obtained under selective anoxic conditions, and degraded 10 mg·L(-1) CCl₄, with less than 10% transient formation of chloroform. Dichloromethane and chloromethane were not detected. Several tetrachloromethane-degrading strains were isolated from these enrichments, including bacteria from the Klebsiella and Clostridium genera closely related to previously described CCl₄ degrading bacteria, and strain TM1, assigned to the genus Pelosinus, for which this property was not yet described. Pelosinus sp. TM1, an oxygen-tolerant, Gram-positive bacterium with strictly anaerobic metabolism, excreted a thermostable metabolite into the culture medium that allowed extracellular CCl₄ transformation. As estimated by T-RFLP, phylotypes of CCl₄-degrading enrichment cultures represented less than 7%, and archaeal and Pelosinus strains less than 0.5% of the total prokaryotic groundwater community.

Tetrachloromethane-Degrading Bacterial Enrichment Cultures and Isolates from a Contaminated Aquifer

PubMed Central

Penny, Christian; Gruffaz, Christelle; Nadalig, Thierry; Cauchie, Henry-Michel; Vuilleumier, Stéphane; Bringel, Françoise

2015-01-01

Abstract: The prokaryotic community of a groundwater aquifer exposed to high concentrations of tetrachloromethane (CCl4) for more than three decades was followed by terminal restriction fragment length polymorphism (T-RFLP) during pump-and-treat remediation at the contamination source. Bacterial enrichments and isolates were obtained under selective anoxic conditions, and degraded 10 mg·L−1 CCl4, with less than 10% transient formation of chloroform. Dichloromethane and chloromethane were not detected. Several tetrachloromethane-degrading strains were isolated from these enrichments, including bacteria from the Klebsiella and Clostridium genera closely related to previously described CCl4 degrading bacteria, and strain TM1, assigned to the genus Pelosinus, for which this property was not yet described. Pelosinus sp. TM1, an oxygen-tolerant, Gram-positive bacterium with strictly anaerobic metabolism, excreted a thermostable metabolite into the culture medium that allowed extracellular CCl4 transformation. As estimated by T-RFLP, phylotypes of CCl4-degrading enrichment cultures represented less than 7%, and archaeal and Pelosinus strains less than 0.5% of the total prokaryotic groundwater community. PMID:27682092

Seasonal variation in the biocontrol efficiency of bacterial wilt is driven by temperature-mediated changes in bacterial competitive interactions.

PubMed

Wei, Zhong; Huang, Jianfeng; Yang, Tianjie; Jousset, Alexandre; Xu, Yangchun; Shen, Qirong; Friman, Ville-Petri

2017-10-01

Microbe-based biocontrol applications hold the potential to become an efficient way to control plant pathogen disease outbreaks in the future. However, their efficiency is still very variable, which could be due to their sensitivity to the abiotic environmental conditions.Here, we assessed how environmental temperature variation correlates with ability of Ralstonia pickettii , an endophytic bacterial biocontrol agent, to suppress the Ralstonia solanacearum pathogen during different tomato crop seasons in China.We found that suppression of the pathogen was highest when the seasonal mean temperatures were around 20 °C and rapidly decreased with increasing mean crop season temperatures. Interestingly, low levels of disease incidence did not correlate with low pathogen or high biocontrol agent absolute densities. Instead, the biocontrol to pathogen density ratio was a more important predictor of disease incidence levels between different crop seasons. To understand this mechanistically, we measured the growth and strength of competition between the biocontrol agent and the pathogen over a naturally occurring temperature gradient in vitro . We found that the biocontrol strain grew relatively faster at low temperature ranges, and the pathogen at high temperature ranges, and that similar to field experiments, pathogen suppression peaked at 20 °C.Together, our results suggest that temperature-mediated changes in the strength of bacterial competition could potentially explain the variable R. solanacearum biocontrol outcomes between different crop seasons in China. Synthesis and applications . Our results suggest that abiotic environmental conditions, such as temperature, can affect the efficacy of biocontrol applications. Thus, in order to develop more consistent biocontrol applications in the future, we might need to find and isolate bacterial strains that can retain their functionality regardless of the changing environmental conditions.

Vitellogenin from the Silkworm, Bombyx mori: An Effective Anti-Bacterial Agent

PubMed Central

Kumar, Manish; Prasad, Tulika; Kannan, Mani; König, Simone

2013-01-01

Silkworm, Bombyx mori, vitellogenin (Vg) was isolated from perivisceral fat body of day 3 of pupa. Both Vg subunits were co-purified as verified by mass spectrometry and immunoblot. Purified Vg responded to specific tests for major posttranslational modifications on native gels indicating its nature as lipo-glyco-phosphoprotein. The Vg fraction had strong antibacterial activity against Gram negative bacterium Escherichia coli and Gram positive bacterium Bacillus subtilis. Microscopic images showed binding of Vg to bacterial cells and their destruction. When infected silkworm larvae were treated with purified Vg they survived the full life cycle in contrast to untreated animals. This result showed that Vg has the ability to inhibit the proliferation of bacteria in the silkworm fluid system without disturbing the regular metabolism of the host. PMID:24058454

BACTERIAL WATERBORNE PATHOGENS

EPA Science Inventory

Bacterial pathogens are examples of classical etiological agents of waterborne disease. While these agents no longer serve as major threats to U.S. water supplies, they are still important pathogens in areas with substandard sanitation and poor water treatment facilities. In th...

Bacterial agents causing meningitis during 2013-2014 in Turkey: A multi-center hospital-based prospective surveillance study.

PubMed

Ceyhan, Mehmet; Ozsurekci, Yasemin; Gürler, Nezahat; Karadag Oncel, Eda; Camcioglu, Yıldız; Salman, Nuran; Celik, Melda; Emiroglu, Melike Keser; Akin, Fatih; Tezer, Hasan; Parlakay, Aslinur Ozkaya; Tuygun, Nilden; Tamburaci, Diyar; Dinleyici, Ener Cagri; Karbuz, Adem; Uluca, Ünal; Alhan, Emre; Çay, Ümmühan; Kurugol, Zafer; Hatipoğlu, Nevin; Şiraneci, Rengin; İnce, Tolga; Sensoy, Gülnar; Belet, Nursen; Coskun, Enes; Yilmaz, Fatih; Hacimustafaoglu, Mustafa; Celebi, Solmaz; Celik, Ümit; Ozen, Metehan; Akaslan, Aybüke; Devrim, İlker; Kuyucu, Necdet; Öz, Fatmanur; Bozdemir, Sefika Elmas; Kara, Ahu

2016-11-01

This is an observational epidemiological study to describe causes of bacterial meningitis among persons between 1 month and 18 y of age who are hospitalized with suspected bacterial meningitis in 7 Turkish regions. covering 32% of the entire population of Turkey. We present here the results from 2013 and 2014. A clinical case with meningitis was defined according to followings: any sign of meningitis including fever, vomiting, headache, and meningeal irritation in children above one year of age and fever without any documented source, impaired consciousness, prostration and seizures in those < 1 y of age. Single tube multiplex PCR assay was performed for the simultaneous identification of bacterial agents. The specific gene targets were ctrA, bex, and ply for N. meningitidis, Hib, and S. pneumoniae, respectively. PCR positive samples were recorded as laboratory-confirmed acute bacterial meningitis. A total of 665 children were hospitalized for suspected acute meningitis. The annual incidences of acute laboratory-confirmed bacterial meningitis were 0.3 cases / 100,000 population in 2013 and 0.9 cases/100,000 in 2014. Of the 94 diagnosed cases of bacterial meningitis by PCR, 85 (90.4%) were meningococcal and 9 (9.6%) were pneumococcal. Hib was not detected in any of the patients. Among meningococcal meningitis, cases of serogroup Y, A, B and W-135 were 2.4% (n = 2), 3.5% (n = 3), 32.9% (n = 28), and 42.4% (n = 36). No serogroup C was detected among meningococcal cases. Successful vaccination policies for protection from bacterial meningitis are dependent on accurate determination of the etiology of bacterial meningitis. Additionally, the epidemiology of meningococcal disease is dynamic and close monitoring of serogroup distribution is comprehensively needed to assess the benefit of adding meningococcal vaccines to the routine immunization program.

Sequence-Specific Affinity Chromatography of Bacterial Small Regulatory RNA-Binding Proteins from Bacterial Cells.

PubMed

Gans, Jonathan; Osborne, Jonathan; Cheng, Juliet; Djapgne, Louise; Oglesby-Sherrouse, Amanda G

2018-01-01

Bacterial small RNA molecules (sRNAs) are increasingly recognized as central regulators of bacterial stress responses and pathogenesis. In many cases, RNA-binding proteins are critical for the stability and function of sRNAs. Previous studies have adopted strategies to genetically tag an sRNA of interest, allowing isolation of RNA-protein complexes from cells. Here we present a sequence-specific affinity purification protocol that requires no prior genetic manipulation of bacterial cells, allowing isolation of RNA-binding proteins bound to native RNA molecules.

Isolation and Characterization of phiLLS, a Novel Phage with Potential Biocontrol Agent against Multidrug-Resistant Escherichia coli

PubMed Central

Amarillas, Luis; Rubí-Rangel, Lucia; Chaidez, Cristobal; González-Robles, Arturo; Lightbourn-Rojas, Luis; León-Félix, Josefina

2017-01-01

Foodborne diseases are a serious and growing problem, and the incidence and prevalence of antimicrobial resistance among foodborne pathogens is reported to have increased. The emergence of antibiotic-resistant bacterial strains demands novel strategies to counteract this epidemic. In this regard, lytic bacteriophages have reemerged as an alternative for the control of pathogenic bacteria. However, the effective use of phages relies on appropriate biological and genomic characterization. In this study, we present the isolation and characterization of a novel bacteriophage named phiLLS, which has shown strong lytic activity against generic and multidrug-resistant Escherichia coli strains. Transmission electron microscopy of phiLLS morphology revealed that it belongs to the Siphoviridae family. Furthermore, this phage exhibited a relatively large burst size of 176 plaque-forming units per infected cell. Phage phiLLS significantly reduced the growth of E. coli under laboratory conditions. Analyses of restriction profiles showed the presence of submolar fragments, confirming that phiLLS is a pac-type phage. Phylogenetic analysis based on the amino acid sequence of large terminase subunits confirmed that this phage uses a headful packaging strategy to package their genome. Genomic sequencing and bioinformatic analysis showed that phiLLS is a novel bacteriophage that is most closely related to T5-like phages. In silico analysis indicated that the phiLLS genome consists of 107,263 bp (39.0 % GC content) encoding 160 putative ORFs, 16 tRNAs, several potential promoters and transcriptional terminators. Genome analysis suggests that the phage phiLLS is strictly lytic without carrying genes associated with virulence factors and/or potential immunoreactive allergen proteins. The bacteriophage isolated in this study has shown promising results in the biocontrol of bacterial growth under in vitro conditions, suggesting that it may prove useful as an alternative agent for the

Isolation and Characterization of phiLLS, a Novel Phage with Potential Biocontrol Agent against Multidrug-Resistant Escherichia coli.

PubMed

Amarillas, Luis; Rubí-Rangel, Lucia; Chaidez, Cristobal; González-Robles, Arturo; Lightbourn-Rojas, Luis; León-Félix, Josefina

2017-01-01

Foodborne diseases are a serious and growing problem, and the incidence and prevalence of antimicrobial resistance among foodborne pathogens is reported to have increased. The emergence of antibiotic-resistant bacterial strains demands novel strategies to counteract this epidemic. In this regard, lytic bacteriophages have reemerged as an alternative for the control of pathogenic bacteria. However, the effective use of phages relies on appropriate biological and genomic characterization. In this study, we present the isolation and characterization of a novel bacteriophage named phiLLS, which has shown strong lytic activity against generic and multidrug-resistant Escherichia coli strains. Transmission electron microscopy of phiLLS morphology revealed that it belongs to the Siphoviridae family. Furthermore, this phage exhibited a relatively large burst size of 176 plaque-forming units per infected cell. Phage phiLLS significantly reduced the growth of E. coli under laboratory conditions. Analyses of restriction profiles showed the presence of submolar fragments, confirming that phiLLS is a pac -type phage. Phylogenetic analysis based on the amino acid sequence of large terminase subunits confirmed that this phage uses a headful packaging strategy to package their genome. Genomic sequencing and bioinformatic analysis showed that phiLLS is a novel bacteriophage that is most closely related to T5-like phages. In silico analysis indicated that the phiLLS genome consists of 107,263 bp (39.0 % GC content) encoding 160 putative ORFs, 16 tRNAs, several potential promoters and transcriptional terminators. Genome analysis suggests that the phage phiLLS is strictly lytic without carrying genes associated with virulence factors and/or potential immunoreactive allergen proteins. The bacteriophage isolated in this study has shown promising results in the biocontrol of bacterial growth under in vitro conditions, suggesting that it may prove useful as an alternative agent for the

Insight into Cr6+ reduction efficiency of Rhodococcus erythropolis isolated from coalmine waste water.

PubMed

Banerjee, Soumya; Joshi, S R; Mandal, Tamal; Halder, Gopinath

2017-01-01

A microbial treatment of Cr 6+ contaminated wastewater with a chromium reducing bacteria isolated from coal mine area was investigated. In a series of batch study metal removal was executed under different parametric conditions which include pH (2-7), temperature (20-50 °C), initial Cr 6+ concentration (1-100 mg/L), substrate utilization and its overall effect on biomass generation. Impact of oxygen availability was checked at different agitation speed and its role on the remedial process. Liquid phase reduction of Cr 6+ was measured in terms of substrate reduction and total biomass yield. The bacterium species isolated was able to tolerate Cr 6+ over a wide range from 1 to 100 mg/L before it reached minimum inhibition concentration. Apart from Cr 6+ , the bacterial isolate showed tolerance towards Fe, As, Cu, Ag, Zn, Mn, Mg and Pb. Removal mechanism adopted by the bacterium recommended that it employed accumulation of Cr 6+ as Cr 3+ both within and outside the cell. Classical Monod equation was used to determine the biokinetics of the bacterial isolate along with the interference of metal ion concentration and substrate utilization. Cr 6+ removal was found prominent even in bimetallic solutions. The bacterial isolate was confirmed to be Rhodococcus erythopolis by 16s rRNA molecular characterization. Thus the bacterial isolate obtained from the coal mine area proved to be a potential agent for microbial remediation of Cr 6+ laden waste water. Copyright © 2016 Elsevier Ltd. All rights reserved.

Complete Genome Sequence of a Putative New Bacterial Strain, I507, Isolated from the Indian Ocean

PubMed Central

Wang, Shu-yan; Wei, Jia-qiang

2018-01-01

ABSTRACT Bacterial strain I507 was isolated from the central Indian Ocean and may be a potential novel species, according to the 16S rRNA gene sequence. Here, we present its complete genome sequence and expect that it will provide researchers with valuable information to further understand its classification and function in the future. PMID:29674539

Socioeconomic and Behavioral Factors Leading to Acquired Bacterial Resistance to Antibiotics in Developing Countries

PubMed Central

Okeke, Iruka N.; Lamikanra, Adebayo

1999-01-01

In developing countries, acquired bacterial resistance to antimicrobial agents is common in isolates from healthy persons and from persons with community-acquired infections. Complex socioeconomic and behavioral factors associated with antibiotic resistance, particularly regarding diarrheal and respiratory pathogens, in developing tropical countries, include misuse of antibiotics by health professionals, unskilled practitioners, and laypersons; poor drug quality; unhygienic conditions accounting for spread of resistant bacteria; and inadequate surveillance. PMID:10081668

Identification and evaluation of agents isolated from traditionally used herbs against Ophiophagus hannah venom.

PubMed

Salama, R; Sattayasai, J; Gande, A K; Sattayasai, N; Davis, M; Lattmann, E

2012-02-01

The aim of this study was firstly to identify active molecules in herbs, that are traditionally used for the treatment of snake bite, such as Curcuma antinaia, Curcuma contravenenum, Andrographis paniculata, and Tanacetum parthenium; secondly to test similar structurally related molecules and finally to prepare and evaluate an efficient formulation against Ophiophagus hannah venom intoxification. Three labdane based compounds, including labdane dialdehyde, labdane lactone, and labdane trialdehyde and two lactones including 14-deoxy-11,12-didehydroandrographolide and parthenolide were isolated by column chromatography and characterised. Using the isolated rat phrenic nerve-hemidiaphragm preparation, the antagonistic effect of crude extracts, isolated compounds and prepared formulations were measured in vitro on the inhibition of the neuromuscular transmission. Inhibition on muscle contraction, produced by the 5 μg/mL venom, was reversed by test agents in organ bath preparations. A labdane trialdehyde, isolated from C. contravenenum, was identified as the best antagonising agent in the low micromolar range. Tests on formulations of the most potent C. contravenenum extract showed, that the suppository with witepsol H15 was an effective medicine against O. hannah venom. This study elucidated the active compounds, accounting for the antivenin activity of traditionally used herbs and suggested the most suitable formulation, which may help to develop potent medicines for the treatment of snake bite in the future.

In vitro activity of daptomycin and comparator agents against Staphylococcus aureus isolates from intravenous drug users with right endocarditis.

PubMed

Sanchez-Porto, Antonio; Casanova-Roman, Manuel; Casas-Ciria, Javier; Santaella, Maria Jose; Sanchez-Morenilla, Immaculada; Eiros-Bouza, Jose Maria

2010-06-01

There is an increasing need for alternative agents in endocarditis, especially with the increasing incidence of vancomycin-intermediate Staphylococcus aureus (VISA). We evaluated the in vitro activity of daptomycin and several comparator agents against 33 non-duplicate clinical Staphylococcus aureus isolates from intravenous drug users with right endocarditis. Wider microdilution panels were used for all the comparator agents and daptomycin. Daptomycin was also tested using E-test strips. E-test strips were used to confirm the vancomycin MICs. Methicillin-resistant Staphylococcus aureus (MRSA isolates with vancomycin MICs ≥ 2 g/mL were screened using the E-test GRD. In all, 30 isolates were methicillin-susceptible (MSSA) and 3 MRSA. The three MRSA isolates exhibited a false vancomycin MIC >2 g/mL determined by Wider microdilution panels. They were screened using the E-test GRD and they were GRD negative. Their final MIC was 2 g/mL. Three MSSA and three MRSA isolates had a vancomycin MIC of 2 g/mL. Four MSSA isolates had a vancomycin MIC of 1.5 g/mL, daptomycin MIC90 0.25 g/mL, linezolid MIC90 2 g/mL. As regards daptomycin, wider microdilution panels and E-test strips yielded the same results. Our findings suggest that daptomycin and linezolid are a viable alternative for treating right endocarditis and bacteraemia caused by MSSA, MRSA and hVISA.

Erwinia teleogrylli sp. nov., a Bacterial Isolate Associated with a Chinese Cricket

PubMed Central

Liu, Bo; Luo, Jin; Li, Wei; Long, Xiu-Feng; Zhang, Yu-Qin; Zeng, Zhi-Gang; Tian, Yong-Qiang

2016-01-01

A bacterial isolate (SCU-B244T) was obtained in China from crickets (Teleogryllus occipitalis) living in cropland deserted for approximately 10 years. The isolated bacteria were Gram-negative, facultatively anaerobic, oxidase-negative rods. A preliminary analysis of the 16S rRNA gene sequence indicated that the strain belongs to either the genus Erwinia or Pantoea. Analysis of multilocus sequence typing based on concatenated partial atpD, gyrB and infB gene sequences and physiological and biochemical characteristics indicated that the strain belonged to the genus Erwinia, as member of a new species as it was distinct from other known Erwinia species. Further analysis of the 16S rRNA gene showed SCU-B244T to have 94.71% identity to the closest species of that genus, Erwinia oleae (DSM 23398T), which is below the threshold of 97% used to discriminate bacterial species. DNA-DNA hybridization results (5.78±2.52%) between SCU-B244T and Erwinia oleae (DSM 23398T) confirmed that SCU-B244T and Erwinia oleae (DSM 23398T) represent different species combined with average nucleotide identity values which range from 72.42% to 74.41. The DNA G+C content of SCU-B244T was 55.32 mol%, which also differs from that of Erwinia oleae (54.7 to 54.9 mol%). The polyphasic taxonomic approach used here confirmed that the strain belongs to the Erwinia group and represents a novel species. The name Erwinia teleogrylli sp. nov. is proposed for this novel taxon, for which the type strain is SCU-B244T (= CGMCC 1.12772T = DSM 28222T = KCTC 42022T). PMID:26800121

Propionibacterium acnes bacteriophages display limited genetic diversity and broad killing activity against bacterial skin isolates.

PubMed

Marinelli, Laura J; Fitz-Gibbon, Sorel; Hayes, Clarmyra; Bowman, Charles; Inkeles, Megan; Loncaric, Anya; Russell, Daniel A; Jacobs-Sera, Deborah; Cokus, Shawn; Pellegrini, Matteo; Kim, Jenny; Miller, Jeff F; Hatfull, Graham F; Modlin, Robert L

2012-01-01

Investigation of the human microbiome has revealed diverse and complex microbial communities at distinct anatomic sites. The microbiome of the human sebaceous follicle provides a tractable model in which to study its dominant bacterial inhabitant, Propionibacterium acnes, which is thought to contribute to the pathogenesis of the human disease acne. To explore the diversity of the bacteriophages that infect P. acnes, 11 P. acnes phages were isolated from the sebaceous follicles of donors with healthy skin or acne and their genomes were sequenced. Comparative genomic analysis of the P. acnes phage population, which spans a 30-year temporal period and a broad geographic range, reveals striking similarity in terms of genome length, percent GC content, nucleotide identity (>85%), and gene content. This was unexpected, given the far-ranging diversity observed in virtually all other phage populations. Although the P. acnes phages display a broad host range against clinical isolates of P. acnes, two bacterial isolates were resistant to many of these phages. Moreover, the patterns of phage resistance correlate closely with the presence of clustered regularly interspaced short palindromic repeat elements in the bacteria that target a specific subset of phages, conferring a system of prokaryotic innate immunity. The limited diversity of the P. acnes bacteriophages, which may relate to the unique evolutionary constraints imposed by the lipid-rich anaerobic environment in which their bacterial hosts reside, points to the potential utility of phage-based antimicrobial therapy for acne. Propionibacterium acnes is a dominant member of the skin microflora and has also been implicated in the pathogenesis of acne; however, little is known about the bacteriophages that coexist with and infect this bacterium. Here we present the novel genome sequences of 11 P. acnes phages, thereby substantially increasing the amount of available genomic information about this phage population

Bacterial Secretome Analysis in Hunt for Novel Bacteriocins with Ability to Control Xanthomonas citri subsp. Citri

PubMed Central

Gholami, Dariush; Goodarzi, Tannaz; Aminzadeh, Saeed; Alavi, Seyed Mehdi; Kazemipour, Nasrin; Farrokhi, Naser

2015-01-01

Background Xanthomonas citri subsp. citri (Xcc), the causative agent of bacterial citrus canker, has affected citriculture worldwide. Varieties of means have been used to minimize its devastating effects, but no attention has been given to bacteriocins. Objectives Here and for the first time, we report the isolation and characterization of two novel bacteriocins. Materials and Methods Secretome containing bacteriocins of isolated bacteria was separated via SDS-PAGE. Each isolated protein band was characterized and checked for its efficacy in controlling two pathogenic isolates of Xcc via disk diffusion assay. The effects of varieties of carbon, nitrogen and phosphate sources were evaluated on both bacterial growth and bacteriocin production via Taguchi orthogonal method. Results The two bacteriocins showed an activity up to 55ºC that were sensitive to proteases suggesting being protein in nature. Analysis of SDS-PAGE purified protein bands of bacterial secretomes with demonstrated potency against Xcc revealed the presence of peptides with relative molecular masses of 16.9 and 17 kDa for Cronobacter and Enterobacter, respectively. Sequence analysis of peptides revealed an HCP1 family VI secretion system homologue for Cronobacter (YP_001439956) and pilin FimA homologue for Enterobacter (CBK85798.1). A Taguchi orthogonal array was also implemented to determine the effect of temperature and eight other chemical factors on bacteriocin production for each bacterium. Conclusions Two peptides with novel antibacterial activities effective against Xcc were isolated, characterized and conditions were optimized for their higher production. PMID:28959294

Remediation of phenol-contaminated soil by a bacterial consortium and Acinetobacter calcoaceticus isolated from an industrial wastewater treatment plant.

PubMed

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).

Common bacterial isolates, clinical outcome and TB meningitis in children admitted at Morogoro Regional Referral Hospital, Tanzania.

PubMed

Chambuso, Ramadhani Salum; Mkhoi, Mkhoi Lord; Kaambo, Evelyn

2017-01-01

Bacterial meningitis is still one of the major causes of deaths, disabilities, and mental retardation in children in Morogoro region. To study the current meningitis burden, we evaluated the common bacterial isolates and clinical outcome of the disease in the region. We conducted a hospital-based prospective study on 1352 children aged between 7 days and 12 years admitted in pediatric wards at Morogoro Regional Referral Hospital for 7 months. Cerebrospinal fluid (CSF) for laboratory microbiological examination was collected by lumbar puncture in 72 children with signs and symptoms of meningitis. Latex agglutination test was used to confirm the bacterial colonies in the culture. Chi-square test was used for relative risk with 95% confidence intervals; statistical analysis and tests were considered statistically significant when P < 0.05. Among 72 CSF samples, 23 (31.9%) were positive for Streptococcus pneumoniae, 6 (8.3%) for Haemophilus influenzae, 5 (6.9%) for Group B Streptococcus, 3 (4.2%) for Escherichia coli, and 1 (1.4%) was positive for Mycobacterium tuberculosis. Furthermore, 34 CSF samples showed no bacteria growth in the culture media. In addition, 39 children (54.2%) did not respond to the treatment, whereas 79.5% (n = 39) of them died, while 20.5% (n = 39) of them were referred to a tertiary hospital. Nevertheless, the incidence of meningitis infection was 5.3% (n = 1352) among the admitted children. S. pneumoniae was the major laboratory-confirmed bacterial isolate associated with meningitis in children. We report for the first time the presence of tuberculous meningitis in Morogoro region. Ziehl-Neelsen staining for acid-fast bacilli should be mandatory for any case clinically suspected for meningitis.

Activity of Norspermidine on Bacterial Biofilms of Multidrug-Resistant Clinical Isolates Associated with Persistent Extremity Wound Infections.

PubMed

Cardile, Anthony P; Woodbury, Ronald L; Sanchez, Carlos J; Becerra, Sandra C; Garcia, Rebecca A; Mende, Katrin; Wenke, Joseph C; Akers, Kevin S

2017-01-01

Biofilm formation is a major virulence factor for numerous pathogenic bacteria and is cited as a central event in the pathogenesis of chronic human infections, which is in large part due to excessive extracellular matrix secretion and metabolic changes that occur within the biofilm rendering them highly tolerant to antimicrobial treatments. Polyamines, including norspermidine, play central roles in bacterial biofilm development, but have also recently been shown to inhibit biofilm formation in select strains of various pathogenic bacteria. The aim of this study was to evaluate in vitro the biofilm dispersive and inhibitory activities of norspermidine against multidrug-resistant clinical isolates of Acinetobacter baumannii(n = 4), Klebsiella pneumoniae (n = 3), Pseudomonas aeruginosa (n = 5) and Staphylococcus aureus (n = 4) associated with chronic extremity wound infections using the semi-quantitative 96-well plate method and confocal laser microscopy. In addition to the antibiofilm activity, biocompatibility of norspermidine was also evaluated by measuring toxicity in vitro to human cell lines and whole porcine tissue explants using MTT viability assay and histological analysis. Norspermidine (5-20 mM) had variable dispersive and inhibitory activity on biofilms which was dependent on both the strain and species. Of the clinical bacterial species evaluated herein, A. baumannii isolates were the most sensitive to the effect of norspermidine, which was in part due to the inhibitory effects of norspermidine on bacterial motility and expression of genes involved in the production of homoserine lactones and quorum sensing molecules both essential for biofilm formation. Importantly, exposure of cell lines and whole tissues to norspermidine for prolonged periods of time (≥24 h) was observed to reduce viability and alter tissue histology in a time and concentration dependent manner, with 20 mM exposure having the greatest negative effects on both tissues and individual

Lyme disease: a selective medium for isolation of the suspected etiological agent, a spirochete.

PubMed Central

Johnson, S E; Klein, G C; Schmid, G P; Bowen, G S; Feeley, J C; Schulze, T

1984-01-01

A simple procedure with a new selective culture medium for the isolation of the suspected etiological agent of Lyme disease from ticks is described. Live ticks (Ixodes dammini) were ground with a mortar and pestle, and the suspensions were inoculated into a selective and nonselective medium. The selective medium, which contained kanamycin and 5-fluorouracil, yielded positive spirochete cultures from 100% of the pooled ticks and from 79% of the single tick specimens. The isolation rate for the nonselective medium was 0% from the tick pools and 58% from the single tick specimens. PMID:6361065

Assembled sequence contigs by SOAPdenova and Volvet algorithms from metagenomic short reads of a new bacterial isolate of gut origin

USDA-ARS?s Scientific Manuscript database

Assembled sequence contigs by SOAPdenova and Volvet algorithms from metagenomic short reads of a new bacterial isolate of gut origin. This study included 2 submissions with a total of 9.8 million bp of assembled contigs....

Amylase production potentials of bacterial isolates obtained from the gut of Oryctes rhinoceros larvae

NASA Astrophysics Data System (ADS)

Aryati, P. C.; Pangastuti, A.; Sari, S. L. A.

2017-04-01

Amylase is one of the main enzymes used in industry, such as food, detergent, textile, and pharmaceutical industry. Amylase can be produced by plants, animals, and microorganisms. However, bacterial and fungal amylases have dominated application in industries. This research was aimed to determine amylolytic activity of bacteria isolated from the gut of Oryctes rhinoceros larvae. Based on clear zone formation, 9 from 11 isolates showed amylolytic activity. Isolates with the widest clear zone, i.e Bacillus subtilis GOR1, Bacillus cereus GOR3, and Bacillus pumilus GOR2, were screened for amylolytic activity based on reduction sugar production. The result showed that Bacillus subtilis GOR1 was the most potential as amylase producer, showed by the widest clear zone 5.224 cm2 and highest reduction sugar production 0.0235 mg/ml. Highest amylase specific activity (0.1447 U/mg protein) was obtained at 60°C and pH 7. Amylase activity was stable for 3 hours at 60°C with residual activity respectively was 59.7%.

Resistance profiles to antimicrobial agents in bacteria isolated from acute endodontic infections: systematic review and meta-analysis.

PubMed

Lang, Pauline M; Jacinto, Rogério C; Dal Pizzol, Tatiane S; Ferreira, Maria Beatriz C; Montagner, Francisco

2016-11-01

Infected root canal or acute apical abscess exudates can harbour several species, including Fusobacterium, Porphyromonas, Prevotella, Parvimonas, Streptococcus, Treponema, Olsenella and not-yet cultivable species. A systematic review and meta-analysis was performed to assess resistance rates to antimicrobial agents in clinical studies that isolated bacteria from acute endodontic infections. Electronic databases and the grey literature were searched up to May 2015. Clinical studies in humans evaluating the antimicrobial resistance of primary acute endodontic infection isolates were included. PRISMA guidelines were followed. A random-effect meta-analysis was employed. The outcome was described as the pooled resistance rates for each antimicrobial agent. Heterogeneity and sensitivity analyses were performed. Subgroup analyses were conducted based upon report or not of the use of antibiotics prior to sampling as an exclusion factor (subgroups A and B, respectively). Data from seven studies were extracted. Resistance rates for 15 different antimicrobial agents were evaluated (range, 3.5-40.0%). Lower resistance rates were observed for amoxicillin/clavulanic acid and amoxicillin; higher resistance rates were detected for tetracycline. Resistance rates varied according to previous use of an antimicrobial agent as demonstrated by the subgroup analyses. Heterogeneity was observed for the resistance profiles of penicillin G in subgroup A and for amoxicillin, clindamycin, metronidazole and tetracycline in subgroup B. Sensitivity analyses demonstrated that resistance rates changed for metronidazole, clindamycin, tetracycline and amoxicillin. These findings suggest that clinical isolates had low resistance to β-lactams. Further well-designed studies are needed to clarify whether the differences in susceptibility among the antimicrobial agents may influence clinical responses to treatment. Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights

Characterization of bacterial diversity associated with calcareous deposits and drip-waters, and isolation of calcifying bacteria from two Colombian mines.

PubMed

García G, Mariandrea; Márquez G, Marco Antonio; Moreno H, Claudia Ximena

2016-01-01

Bacterial carbonate precipitation has implications in geological processes and important biotechnological applications. Bacteria capable of precipitating carbonates have been isolated from different calcium carbonate deposits (speleothems) in caves, soil, freshwater and seawater around the world. However, the diversity of bacteria from calcareous deposits in Colombia, and their ability to precipitate carbonates, remains unknown. In this study, conventional microbiological methods and molecular tools, such as temporal temperature gradient electrophoresis (TTGE), were used to assess the composition of bacterial communities associated with carbonate deposits and drip-waters from two Colombian mines. A genetic analysis of these bacterial communities revealed a similar level of diversity, based on the number of bands detected using TTGE. The dominant phylogenetic affiliations of the bacteria, determined using 16S rRNA gene sequencing, were grouped into two phyla: Proteobacteria and Firmicutes. Within these phyla, seven genera were capable of precipitating calcium carbonates: Lysinibacillus, Bacillus, Strenotophomonas, Brevibacillus, Methylobacterium, Aeromicrobium and Acinetobacter. FTIR and SEM/EDX were used to analyze calcium carbonate crystals produced by isolated Acinetobacter gyllenbergii. The results showed that rhombohedral and angular calcite crystals with sizes of 90μm were precipitated. This research provides information regarding the presence of complex bacterial communities in secondary carbonate deposits from mines and their ability to precipitate calcium carbonate from calcareous deposits of Colombian mines. Copyright © 2015 Elsevier GmbH. All rights reserved.

Characterization of Asymptomatic Bacteriuria Escherichia coli Isolates in Search of Alternative Strains for Efficient Bacterial Interference against Uropathogens

PubMed Central

Stork, Christoph; Kovács, Beáta; Rózsai, Barnabás; Putze, Johannes; Kiel, Matthias; Dorn, Ágnes; Kovács, Judit; Melegh, Szilvia; Leimbach, Andreas; Kovács, Tamás; Schneider, György; Kerényi, Monika; Emödy, Levente; Dobrindt, Ulrich

2018-01-01

Asymptomatic bacterial colonization of the urinary bladder (asymptomatic bacteriuria, ABU) can prevent bladder colonization by uropathogens and thus symptomatic urinary tract infection (UTI). Deliberate bladder colonization with Escherichia coli ABU isolate 83972 has been shown to outcompete uropathogens and prevent symptomatic UTI by bacterial interference. Many ABU isolates evolved from uropathogenic ancestors and, although attenuated, may still be able to express virulence-associated factors. Our aim was to screen for efficient and safe candidate strains that could be used as alternatives to E. coli 83972 for preventive and therapeutic bladder colonization. To identify ABU E. coli strains with minimal virulence potential but maximal interference efficiency, we compared nine ABU isolates from diabetic patients regarding their virulence- and fitness-associated phenotypes in vitro, their virulence in a murine model of sepsis and their genome content. We identified strains in competitive growth experiments, which successfully interfere with colonization of ABU isolate 83972 or uropathogenic E. coli strain 536. Six isolates were able to outcompete E. coli 83972 and two of them also outcompeted UPEC 536 during growth in urine. Superior competitiveness was not simply a result of better growth abilities in urine, but seems also to involve expression of antagonistic factors. Competitiveness in urine did not correlate with the prevalence of determinants coding for adhesins, iron uptake, toxins, and antagonistic factors. Three ABU strains (isolates 61, 106, and 123) with superior competitiveness relative to ABU model strain 83972 display low in vivo virulence in a murine sepsis model, and susceptibility to antibiotics. They belong to different phylogroups and differ in the presence of ExPEC virulence- and fitness-associated genes. Importantly, they all lack marked cytotoxic activity and exhibit a high LD50 value in the sepsis model. These strains represent promising

Prevalence of Antibiotic-resistance Enterobacteriaceae strains Isolated from Chicken Meat at Traditional Markets in Surabaya, Indonesia

NASA Astrophysics Data System (ADS)

Yulistiani, R.; Praseptiangga, D.; Supyani; Sudibya; Raharjo, D.; Shirakawa, T.

2017-04-01

Antibiotic resistance in bacteria from the family Enterobacteriaceae is an important indicator of the emergence of resistant bacterial strains in the community. This study investigated the prevalence of antibiotic-resistant Enterobacteriaceae isolated from chicken meat sold at traditional markets in Surabaya Indonesia. In all, 203 isolates (43 Salmonella spp., 53 Escherichia coli, 16 Shigella spp., 22 Citrobacter spp., 13 Klebsiella spp, 24 Proteus spp., 15 Yersinia spp., 7 Enterobacter spp., 6 Serratia spp., 3 Edwardsiella spp. were resistant to tetracycline (69.95 %), nalidixid acid (54.19 %), sulfamethoxazole/sulfamethizole (42.36 %), chloramphenicol (12.81%), cefoxitin (6.40 %), gentamicin (5.91 %). Tetracycline was the antimicrobial that showed the highest frequency of resistance among Salmonella, E. coli, Citrobacter, Proteus and Erdwardsiella isolates, and nalidixid acid was second frequency of resistance. Overall, 124 (61.08 %) out of 203 isolates demonstrated multidrug resistance to at least two unrelated antimicrobial agents. The high rate of antimicrobial resistance in bacterial isolates from chicken meat may have major implications for human and animal health with adverse economic implications.

Wheat seeds harbour bacterial endophytes with potential as plant growth promoters and biocontrol agents of Fusarium graminearum.

PubMed

Díaz Herrera, Silvana; Grossi, Cecilia; Zawoznik, Myriam; Groppa, María Daniela

2016-01-01

The role of endophytic communities of seeds is still poorly characterised. The purpose of this work was to survey the presence of bacterial endophytes in the seeds of a commercial wheat cultivar widely sown in Argentina and to look for plant growth promotion features and biocontrol abilities against Fusarium graminearum among them. Six isolates were obtained from wheat seeds following a culture-dependent protocol. Four isolates were assignated to Paenibacillus genus according to their 16S rRNA sequencing. The only gammaproteobacteria isolated, presumably an Enterobactereaceae of Pantoea genus, was particularly active as IAA and siderophore producer, and also solubilised phosphate and was the only one that grew on N-free medium. Several of these isolates demonstrated ability to restrain F. graminearum growth on dual culture and in a bioassay using barley and wheat kernels. An outstanding ability to form biofilm on an inert surface was corroborated for those Paenibacillus which displayed greater biocontrol of F. graminearum, and the inoculation with one of these isolates in combination with the Pantoea isolate resulted in greater chlorophyll content in barley seedlings. Our results show a significant ecological potential of some components of the wheat seed endophytic community. Copyright © 2016 Elsevier GmbH. All rights reserved.

Dose modification in e.coli by a constitutive radioprotective agent isolated from m. radiodurans

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldstein, Lawrence S.

1972-01-01

A constitutive low molecular weight radioprotective agent has been isolated from a colorless mutant of Micrococcus radiodurans. The effect of radioprotective extract was also investigated in three mutant strains of E.coli B/r differing from one another at a given locus concerned with the repair of radiation induced damage/

Isolation of bacterial extrachromosomal DNA from human dental plaque associated with periodontal disease, using transposon-aided capture (TRACA).

PubMed

Warburton, Philip J; Allan, Elaine; Hunter, Stephanie; Ward, John; Booth, Veronica; Wade, William G; Mullany, Peter

2011-11-01

The human oral cavity is host to a complex microbial community estimated to comprise >700 bacterial species, of which at least half are thought to be not yet cultivable in vitro. To investigate the plasmids present in this community, we used a transposon-aided capture system, which allowed the isolation of plasmids from human oral supra- and subgingival plaque samples. Thirty-two novel plasmids and a circular molecule that could be an integrase-generated circular intermediate were isolated. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Genetic analysis of a bacterial genetic exchange element: The gene transfer agent of Rhodobacter capsulatus

PubMed Central

Lang, Andrew S.; Beatty, J. T.

2000-01-01

An unusual system of genetic exchange exists in the purple nonsulfur bacterium Rhodobacter capsulatus. DNA transmission is mediated by a small bacteriophage-like particle called the gene transfer agent (GTA) that transfers random 4.5-kb segments of the producing cell's genome to recipient cells, where allelic replacement occurs. This paper presents the results of gene cloning, analysis, and mutagenesis experiments that show that GTA resembles a defective prophage related to bacteriophages from diverse genera of bacteria, which has been adopted by R. capsulatus for genetic exchange. A pair of cellular proteins, CckA and CtrA, appear to constitute part of a sensor kinase/response regulator signaling pathway that is required for expression of GTA structural genes. This signaling pathway controls growth-phase-dependent regulation of GTA gene messages, yielding maximal gene expression in the stationary phase. We suggest that GTA is an ancient prophage remnant that has evolved in concert with the bacterial genome, resulting in a genetic exchange process controlled by the bacterial cell. PMID:10639170

In Vitro Evaluation of Delafloxacin Activity when Tested Against Contemporary community-Acquired Bacterial Respiratory Tract Infection Isolates (2014–2016): Results from the Sentry Antimicrobial Surveillance Program

PubMed Central

Shortridge, Dee; Streit, Jennifer M; Huband, Michael D; Rhomberg, Paul R; Flamm, Robert K

2017-01-01

Abstract Background Delafloxacin (DLX) is a broad-spectrum fluoroquinolone (FQ) antibacterial that has completed clinical development (oral and intravenous formulations) with the new drug application currently under the Food and Drug Administration review for the treatment of acute bacterial skin and skin structure infections (ABSSSI). DLX is also in clinical trials for community-acquired bacterial pneumonia. In this study, in vitro susceptibility results for DLX and comparator agents were determined for clinical isolates from community-acquired respiratory tract infections (CA-RTI) collected in medical centers in the United States and Europe participating in the SENTRY surveillance program during 2014–2016. Methods A total of 3,093 isolates that included 1,673 Streptococcus pneumoniae (SPN), 805 Haemophilus influenzae (HI) and 555 Moraxella catarrhalis (MC) were collected during 2014–2016 and included only 1 isolate/patient/infection episode. Isolate identifications were confirmed at JMI Laboratories. Susceptibility testing was performed according to CLSI reference broth microdilution methodology, and results were interpreted per CLSI (2017) breakpoints. Other antibacterials tested included levofloxacin (LVX) and penicillin. Β-lactamase production for HI and MC was determined by the nitrocephin disk test. Results DLX demonstrated potent in vitro activity against SPN (MIC50/90 0.015/0.03 mg/L). Activity remained the same for penicillin-intermediate or -resistant isolates. For 23 LVX nonsusceptible SPN, the DLX MIC50/90 were 0.12/0.25 mg/L with all isolates having DLX MIC values ≤1 mg/L. For HI, the DLX MIC50/90 were ≤0.001/0.004 mg/L, and for MC the MIC50/90 were 0.008/0.008 mg/L. DLX activity was unaffected by the presence of β-lactamase for either HI or MC. Activity of DLX was similar for US and European isolates. Conclusion Delafloxacin demonstrated potent in vitro antibacterial activity against CA-RTI pathogens, including SPN, HI, and MC. These

Lactobacillus species isolated from vaginal secretions of healthy and bacterial vaginosis-intermediate Mexican women: a prospective study

PubMed Central

2013-01-01

Background Lactobacillus jensenii, L. iners, L. crispatus and L. gasseri are the most frequently occurring lactobacilli in the vagina. However, the native species vary widely according to the studied population. The present study was performed to genetically determine the identity of Lactobacillus strains present in the vaginal discharge of healthy and bacterial vaginosis (BV) intermediate Mexican women. Methods In a prospective study, 31 strains preliminarily identified as Lactobacillus species were isolated from 21 samples collected from 105 non-pregnant Mexican women. The samples were classified into groups according to the Nugent score criteria proposed for detection of BV: normal (N), intermediate (I) and bacterial vaginosis (BV). We examined the isolates using culture-based methods as well as molecular analysis of the V1–V3 regions of the 16S rRNA gene. Enterobacterial repetitive intergenic consensus (ERIC) sequence analysis was performed to reject clones. Results Clinical isolates (25/31) were classified into four groups based on sequencing and analysis of the 16S rRNA gene: L. acidophilus (14/25), L. reuteri (6/25), L. casei (4/25) and L. buchneri (1/25). The remaining six isolates were presumptively identified as Enterococcus species. Within the L. acidophilus group, L. gasseri was the most frequently isolated species, followed by L. jensenii and L. crispatus. L. fermentum, L. rhamnosus and L. brevis were also isolated, and were placed in the L. reuteri, L. casei and L. buchneri groups, respectively. ERIC profile analysis showed intraspecific variability amongst the L. gasseri and L. fermentum species. Conclusions These findings agree with previous studies showing that L. crispatus, L. gasseri and L. jensenii are consistently present in the healthy vaginal ecosystem. Additional species or phylotypes were detected in the vaginal microbiota of the non-pregnant Mexican (Hispanic-mestizo) population, and thus, these results further our understanding of

Comparison of hydrogen peroxide and peracetic acid as isolator sterilization agents in a hospital pharmacy.

PubMed

Bounoure, Frederic; Fiquet, Herve; Arnaud, Philippe

2006-03-01

The efficacy of hydrogen peroxide and peracetic acid as isolator sterilization agents was compared. Sterilization and efficacy tests were conducted in a flexible 0.8-m3 transfer isolator using a standard load of glass bottles and sterile medical devices in their packing paper. Bacillus stearothermophilus spores were placed in six critical locations of the isolator and incubated at 55 degrees C in a culture medium for 14 days. Sterilization by 4.25 mL/m3 of 33% vapor-phase hydrogen peroxide and 12.5 mL/m3 of 3.5% peracetic acid was tested in triplicate. Sterility was validated for hydrogen peroxide and peracetic acid at 60, 90, 120, and 180 minutes and at 90, 120, 150, 180, 210, and 240 minutes, respectively. In an efficacy test conducted with an empty isolator, the sterilization time required to destroy B. stearothermophilus spores was 90 minutes for both sterilants, indicating that they have comparable bactericidal properties. During the validation test with a standard load, the sterilization time using hydrogen peroxide was 150 minutes versus 120 minutes with peracetic acid. The glove cuff was particularly difficult for hydrogen peroxide to sterilize, likely due to its slower diffusion time than that of peracetic acid. Hydrogen peroxide is an environmentally safer agent than peracetic acid; however, its bacteriostatic properties, lack of odor, and poor diffusion time may limit its use in sterilizing some materials. Hydrogen peroxide is a useful alternative to peracetic acid for isolator sterilization in a hospital pharmacy or parenteral nutrition preparation unit.

Molecular Survey of Bacterial Zoonotic Agents in Bats from the Country of Georgia (Caucasus).

PubMed

Bai, Ying; Urushadze, Lela; Osikowicz, Lynn; McKee, Clifton; Kuzmin, Ivan; Kandaurov, Andrei; Babuadze, Giorgi; Natradze, Ioseb; Imnadze, Paata; Kosoy, Michael

2017-01-01

Bats are important reservoirs for many zoonotic pathogens. However, no surveys of bacterial pathogens in bats have been performed in the Caucasus region. To understand the occurrence and distribution of bacterial infections in these mammals, 218 bats belonging to eight species collected from four regions of Georgia were examined for Bartonella, Brucella, Leptospira, and Yersinia using molecular approaches. Bartonella DNA was detected in 77 (35%) bats from all eight species and was distributed in all four regions. The prevalence ranged 6-50% per bat species. The Bartonella DNA represented 25 unique genetic variants that clustered into 21 lineages. Brucella DNA was detected in two Miniopterus schreibersii bats and in two Myotis blythii bats, all of which were from Imereti (west-central region). Leptospira DNA was detected in 25 (13%) bats that included four M. schreibersii bats and 21 M. blythii bats collected from two regions. The Leptospira sequences represented five genetic variants with one of them being closely related to the zoonotic pathogen L. interrogans (98.6% genetic identity). No Yersinia DNA was detected in the bats. Mixed infections were observed in several cases. One M. blythii bat and one M. schreibersii bat were co-infected with Bartonella, Brucella, and Leptospira; one M. blythii bat and one M. schreibersii bat were co-infected with Bartonella and Brucella; 15 M. blythii bats and three M. schreibersii bats were co-infected with Bartonella and Leptospira. Our results suggest that bats in Georgia are exposed to multiple bacterial infections. Further studies are needed to evaluate pathogenicity of these agents to bats and their zoonotic potential.

Isolation and analysis of bacteria with antimicrobial activities from the marine sponge Haliclona simulans collected from Irish waters.

PubMed

Kennedy, Jonathan; Baker, Paul; Piper, Clare; Cotter, Paul D; Walsh, Marcella; Mooij, Marlies J; Bourke, Marie B; Rea, Mary C; O'Connor, Paula M; Ross, R Paul; Hill, Colin; O'Gara, Fergal; Marchesi, Julian R; Dobson, Alan D W

2009-01-01

Samples of the marine sponge Haliclona simulans were collected from Irish coastal waters, and bacteria were isolated from these samples. Phylogenetic analyses of the cultured isolates showed that four different bacterial phyla were represented; Bacteriodetes, Actinobacteria, Proteobacteria, and Firmicutes. The sponge bacterial isolates were assayed for the production of antimicrobial substances, and biological activities against Gram-positive and Gram-negative bacteria and fungi were demonstrated, with 50% of isolates showing antimicrobial activity against at least one of the test strains. Further testing showed that the antimicrobial activities extended to the important pathogens Pseudomonas aeruginosa, Clostridium difficile, multi-drug-resistant Staphylococcus aureus, and pathogenic yeast strains. The Actinomycetes were numerically the most abundant producers of antimicrobial activities, although activities were also noted from Bacilli and Pseudovibrio isolates. Surveys for the presence of potential antibiotic encoding polyketide synthase and nonribosomal peptide synthetase genes also revealed that genes for the biosynthesis of these secondary metabolites were present in most bacterial phyla but were particularly prevalent among the Actinobacteria and Proteobacteria. This study demonstrates that the culturable fraction of bacteria from the sponge H. simulans is diverse and appears to possess much potential as a source for the discovery of new medically relevant biological active agents.

Draft Genome Sequence of Xanthomonas arboricola pv. pruni Strain Xap33, Causal Agent of Bacterial Spot Disease on Almond

PubMed Central

Garita-Cambronero, J.; Sena-Vélez, M.; Palacio-Bielsa, A.

2014-01-01

We report the annotated genome sequence of Xanthomonas arboricola pv. pruni strain Xap33, isolated from almond leaves showing bacterial spot disease symptoms in Spain. The availability of this genome sequence will aid our understanding of the infection mechanism of this bacterium as well as its relationship to other species of the same genus. PMID:24903863

Leaf-FISH: Microscale Imaging of Bacterial Taxa on Phyllosphere

PubMed Central

Peredo, Elena L.; Simmons, Sheri L.

2018-01-01

Molecular methods for microbial community characterization have uncovered environmental and plant-associated factors shaping phyllosphere communities. Variables undetectable using bulk methods can play an important role in shaping plant-microbe interactions. Microscale analysis of bacterial dynamics in the phyllosphere requires imaging techniques specially adapted to the high autoflouresence and 3-D structure of the leaf surface. We present an easily-transferable method (Leaf-FISH) to generate high-resolution tridimensional images of leaf surfaces that allows simultaneous visualization of multiple bacterial taxa in a structurally informed context, using taxon-specific fluorescently labeled oligonucleotide probes. Using a combination of leaf pretreatments coupled with spectral imaging confocal microscopy, we demonstrate the successful imaging bacterial taxa at the genus level on cuticular and subcuticular leaf areas. Our results confirm that different bacterial species, including closely related isolates, colonize distinct microhabitats in the leaf. We demonstrate that highly related Methylobacterium species have distinct colonization patterns that could not be predicted by shared physiological traits, such as carbon source requirements or phytohormone production. High-resolution characterization of microbial colonization patterns is critical for an accurate understanding of microbe-microbe and microbe-plant interactions, and for the development of foliar bacteria as plant-protective agents. PMID:29375531

Decreased Phototoxic Effects of TiO₂ Nanoparticles in Consortium of Bacterial Isolates from Domestic Waste Water

PubMed Central

Mathur, Ankita; Kumari, Jyoti; Parashar, Abhinav; T., Lavanya; Chandrasekaran, N.; Mukherjee, Amitava

2015-01-01

This study is aimed to explore the toxicity of TiO2 nanoparticles at low concentrations (0.25, 0.50 & 1.00 μg/ml); on five bacterial isolates and their consortium in waste water medium both in dark and UVA conditions. To critically examine the toxic effects of nanoparticles and the response mechanism(s) offered by microbes, several aspects were monitored viz. cell viability, ROS generation, SOD activity, membrane permeability, EPS release and biofilm formation. A dose and time dependent loss in viability was observed for treated isolates and the consortium. At the highest dose, after 24h, oxidative stress was examined which conclusively showed more ROS generation & cell permeability and less SOD activity in single isolates as compared to the consortium. As a defense mechanism, EPS release was enhanced in case of the consortium against the single isolates, and was observed to be dose dependent. Similar results were noticed for biofilm formation, which substantially increased at highest dose of nanoparticle exposure. Concluding, the consortium showed more resistance against the toxic effects of the TiO2 nanoparticles compared to the individual isolates. PMID:26496250

A Model to Explain Plant Growth Promotion Traits: A Multivariate Analysis of 2,211 Bacterial Isolates

PubMed Central

da Costa, Pedro Beschoren; Granada, Camille E.; Ambrosini, Adriana; Moreira, Fernanda; de Souza, Rocheli; dos Passos, João Frederico M.; Arruda, Letícia; Passaglia, Luciane M. P.

2014-01-01

Plant growth-promoting bacteria can greatly assist sustainable farming by improving plant health and biomass while reducing fertilizer use. The plant-microorganism-environment interaction is an open and complex system, and despite the active research in the area, patterns in root ecology are elusive. Here, we simultaneously analyzed the plant growth-promoting bacteria datasets from seven independent studies that shared a methodology for bioprospection and phenotype screening. The soil richness of the isolate's origin was classified by a Principal Component Analysis. A Categorical Principal Component Analysis was used to classify the soil richness according to isolate's indolic compound production, siderophores production and phosphate solubilization abilities, and bacterial genera composition. Multiple patterns and relationships were found and verified with nonparametric hypothesis testing. Including niche colonization in the analysis, we proposed a model to explain the expression of bacterial plant growth-promoting traits according to the soil nutritional status. Our model shows that plants favor interaction with growth hormone producers under rich nutrient conditions but favor nutrient solubilizers under poor conditions. We also performed several comparisons among the different genera, highlighting interesting ecological interactions and limitations. Our model could be used to direct plant growth-promoting bacteria bioprospection and metagenomic sampling. PMID:25542031

The First Report of Drug Resistant Bacteria Isolated from the Brown-Banded Cockroach, Supella longipalpa, in Ahvaz, South-western Iran

PubMed Central

Vazirianzadeh, Babak; Dehghani, Rouhullah; Mehdinejad, Manijeh; Sharififard, Mona; Nasirabadi, Nersi

2014-01-01

Background The brown-banded cockroach, Supella longipalpa is known as a carrier of pathogenic bacteria in urban environments, but its role is not well documented regarding the carriage of antibiotic-resistant pathogenic bacteria in Iran. The aim of this study was to determine the resistance bacteria isolated from the brown-banded cockroach in Ahvaz, south west of Iran. Methods: Totally 39 cockroaches were collected from kitchen area of houses and identified. All specimens were cultured to isolate the bacterial agents on blood agar and MacConky agar media. The microorganisms were identified using necessary differential and biochemical tests. Antimicrobial susceptibility tests were performed for isolated organisms by Kirby-Bauer’s disk diffusion according to NCLI guideline, using 18 antibiotics. Results: From the 39 collected S. langipalpa, 179 bacterial agents were isolated, 92 of alimentary ducts and 87 of external body surfaces. Isolated bacteria from cockroaches were identified as Enterobacter spp., Klebsiella spp., Citrobacter spp., Escherichia coli, Salmonella spp., Proteus spp., coagulase negative staphylococci, Serratia marcescens, Staphylococcus aureus, and Bacillus species. The pattern resistance rates were determined for gram negative bacilli and gram positive cocci regarding 18 antibiotics. Conclusion: The brown-banded cockroach can be involved in the spread of drug resistant bacteria and increases the possibility of contacting human environment to drug resistant bacteria. Therefore, the potential of removing this insect should be improved. This is the first original report of drug resistant bacteria isolated from the brown-banded cockroach of Iran. PMID:25629065

Prevalence and Bacterial Isolates of Mastitis in Dairy Farms in Selected Districts of Eastern Harrarghe Zone, Eastern Ethiopia

PubMed Central

Abera, Gerema

2017-01-01

The study was conducted from November 2015 to April 2016 to estimate the prevalence of clinical and subclinical mastitis in lactating cows, to assess the associated risk factors, and to isolate the major bacterial pathogens in dairy farms in selected district of Eastern Harrarghe Zone, Eastern Ethiopia. The study was carried out in 384 dairy cows based on data collection, farm visit, animal examination, California mastitis test (CMT), and isolation bacterial pathogens using standard techniques. In the present study the overall mastitis at cow level was 247 (64.3%). The prevalence of clinical and subclinical mastitis and quarter level prevalence for clinical and subclinical mastitis were 12.5% and 51.8% at cow level and 10.7% and 46.4% at quarter level, respectively. Clinically, 101 (6.6%) quarters which belong to 75 (19.5%) animals were found to be with blind teat. In the present study prevalence of mastitis was significantly associated with parity and age (p < 0.05). Bacteriological examination of milk sample revealed 187 isolates where coagulase negative Staphylococcus species (CNS) (34.2%) was the predominant species while Streptococcus faecalis (2.1%) was identified as the least bacteria. The present study concluded that prevalence of mastitis particularly the subclinical mastitis was major problem of dairy cows in the area and hence warrants serious attention. PMID:28352648

Comparison of the cidal activity of tea tree oil and terpinen-4-ol against clinical bacterial skin isolates and human fibroblast cells.

PubMed

Loughlin, R; Gilmore, B F; McCarron, P A; Tunney, M M

2008-04-01

The aim of this study was to compare both the antimicrobial activity of terpinen-4-ol and tea tree oil (TTO) against clinical skin isolates of meticillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci (CoNS) and their toxicity against human fibroblast cells. Antimicrobial activity was compared by using broth microdilution and quantitative in vitro time-kill test methods. Terpinen-4-ol exhibited significantly greater bacteriostatic and bactericidal activity, as measured by minimum inhibitory and bactericidal concentrations, respectively, than TTO against both MRSA and CoNS isolates. Although not statistically significant, time-kill studies also clearly showed that terpinen-4-ol exhibited greater antimicrobial activity than TTO. Comparison of the toxicity of terpinen-4-ol and TTO against human fibroblasts revealed that neither agent, at the concentrations tested, were toxic over the 24-h test period. Terpinen-4-ol is a more potent antibacterial agent against MRSA and CoNS isolates than TTO with neither agent exhibiting toxicity to fibroblast cells at the concentrations tested. Terpinen-4-ol should be considered for inclusion as a single agent in products formulated for topical treatment of MRSA infection. However, further work would initially be required to ensure that resistance would not develop with the use of terpinen-4-ol as a single agent.

Characterization of the spoilage potential of pure and mixed cultures of bacterial species isolated from tropical yellowfin tuna (Thunnus albacares).

PubMed

Silbande, A; Cornet, J; Cardinal, M; Chevalier, F; Rochefort, K; Smith-Ravin, J; Adenet, S; Leroi, F

2018-02-01

The spoilage potential of 28 bacterial strains isolated from spoiled raw yellowfin tuna was evaluated. Bacterial species were inoculated in irradiated tuna matrix. Chemical changes, bacterial growth and sensory quality were monitored during aerobic storage at 8°C. Pseudomonas spp., Enterobacter spp. and Escherichia hermanii had no spoiling effect. Brochothrix thermosphacta and Carnobacterium divergens/maltaromaticum developed moderate unpleasant odours. Hafnia paralvei and Serratia spp. released strong off-odours (pyrrolidine, sulphur/cabbage). No bacterial group (except H. paralvei) combined with Pseudomonas spp. deteriorated the sensory quality of tuna. When C. divergens/maltaromaticum was associated with H. paralvei or B. thermosphacta, the odour is close to the naturally contaminated tuna stored on the same conditions. The pH, total volatile basic nitrogen (TVBN) and trimethylamine (TMA) were not correlated with the spoilage. The bacterial species had a different impact on the sensory quality of the fish. The bacterial interactions lead to an enhancement or an inhibition of the spoilage potential and the bacterial growth. The specific spoilage organism (SSO) appears to be an association of lactic acid bacteria (LAB) with Enterobacteriaceae or B. thermosphacta. Pseudomonas, often dominant at the sensory rejection time, is not a good quality indicator. © 2017 The Society for Applied Microbiology.

Gentamicin Sulfate PEG-PLGA/PLGA-H Nanoparticles: Screening Design and Antimicrobial Effect Evaluation toward Clinic Bacterial Isolates

PubMed Central

Dorati, Rossella; DeTrizio, Antonella; Spalla, Melissa; Migliavacca, Roberta; Pagani, Laura; Pisani, Silvia; Chiesa, Enrica; Modena, Tiziana; Genta, Ida

2018-01-01

Nanotechnology is a promising approach both for restoring or enhancing activity of old and conventional antimicrobial agents and for treating intracellular infections by providing intracellular targeting and sustained release of drug inside infected cells. The present paper introduces a formulation study of gentamicin loaded biodegradable nanoparticles (Nps). Solid-oil-in water technique was studied for gentamicin sulfate nanoencapsulation using uncapped Polylactide-co-glycolide (PLGA-H) and Polylactide-co-glycolide-co-Polyethylenglycol (PLGA-PEG) blends. Screening design was applied to optimize: drug payload, Nps size and size distribution, stability and resuspendability after freeze-drying. PLGA-PEG concentration resulted most significant factor influencing particles size and drug content (DC): 8 w/w% DC and 200 nm Nps were obtained. Stirring rate resulted most influencing factor for size distribution (PDI): 700 rpm permitted to obtain homogeneous Nps dispersion (PDI = 1). Further experimental parameters investigated, by 23 screening design, were: polymer blend composition (PLGA-PEG and PLGA-H), Polyvinylalcohol (PVA) and methanol concentrations into aqueous phase. Drug content was increased to 10.5 w/w%. Nanoparticle lyophilization was studied adding cryoprotectants, polyvinypirrolidone K17 and K32, and sodiumcarboxymetylcellulose. Freeze-drying protocol was optimized by a mixture design. A freeze-dried Nps powder free resuspendable with stable Nps size and payload, was developed. The powder was tested on clinic bacterial isolates demonstrating that after encapsulation, gentamicin sulfate kept its activity. PMID:29329209

Detection of carboxylesterase and esterase activity in culturable gut bacterial flora isolated from diamondback moth, Plutella xylostella (Linnaeus), from India and its possible role in indoxacarb degradation.

PubMed

Ramya, Shanivarsanthe Leelesh; Venkatesan, Thiruvengadam; Srinivasa Murthy, Kottilingam; Jalali, Sushil Kumar; Verghese, Abraham

2016-01-01

Diamondback moth (DBM), Plutella xylostella (Linnaeus), is a notorious pest of brassica crops worldwide and is resistant to all groups of insecticides. The insect system harbors diverse groups of microbiota, which in turn helps in enzymatic degradation of xenobiotic-like insecticides. The present study aimed to determine the diversity of gut microflora in DBM, quantify esterase activity and elucidate their possible role in degradation of indoxacarb. We screened 11 geographic populations of DBM in India and analyzed them for bacterial diversity. The culturable gut bacterial flora underwent molecular characterization with 16S rRNA. We obtained 25 bacterial isolates from larvae (n=13) and adults (n=12) of DBM. In larval gut isolates, gammaproteobacteria was the most abundant (76%), followed by bacilli (15.4%). Molecular characterization placed adult gut bacterial strains into three major classes based on abundance: gammaproteobacteria (66%), bacilli (16.7%) and flavobacteria (16.7%). Esterase activity from 19 gut bacterial isolates ranged from 0.072 to 2.32μmol/min/mg protein. Esterase bands were observed in 15 bacterial strains and the banding pattern differed in Bacillus cereus - KC985225 and Pantoea agglomerans - KC985229. The bands were characterized as carboxylesterase with profenofos used as an inhibitor. Minimal media study showed that B. cereus degraded indoxacarb up to 20%, so it could use indoxacarb for metabolism and growth. Furthermore, esterase activity was greater with minimal media than control media: 1.87 versus 0.26μmol/min/mg protein. Apart from the insect esterases, bacterial carboxylesterase may aid in the degradation of insecticides in DBM. Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Isolation and characterization of butachlor-catabolizing bacterial strain Stenotrophomonas acidaminiphila JS-1 from soil and assessment of its biodegradation potential.

PubMed

Dwivedi, S; Singh, B R; Al-Khedhairy, A A; Alarifi, S; Musarrat, J

2010-07-01

Isolation, characterization and assessment of butachlor-degrading potential of bacterial strain JS-1 in soil. Butachlor-degrading bacteria were isolated using enrichment culture technique. The morphological, biochemical and genetic characteristics based on 16S rDNA sequence homology and phylogenetic analysis confirmed the isolate as Stenotrophomonas acidaminiphila strain JS-1. The strain JS-1 exhibited substantial growth in M9 mineral salt medium supplemented with 3.2 mmol l(-1) butachlor, as a sole source of carbon and energy. The HPLC analysis revealed almost complete disappearance of butachlor within 20 days in soil at a rate constant of 0.17 day(-1) and half-life (t((1/2))) of 4.0 days, following the first-order rate kinetics. The strain JS-1 in stationary phase of culture also produced 21.0 microg ml(-1) of growth hormone indole acetic acid (IAA) in the presence of 500 microg ml(-1) of tryptophan. The IAA production was stimulated at lower concentrations of butachlor, whereas higher concentrations above 0.8 mmol l(-1) were found inhibitory. The isolate JS-1 characterized as Stenotrophomonas acidaminiphila was capable of utilizing butachlor as sole source of carbon and energy. Besides being an efficient butachlor degrader, it substantially produces IAA. The bacterial strain JS-1 has a potential for butachlor remediation with a distinctive auxiliary attribute of plant growth stimulation.

Isolation of hydroquinone (benzene-1,4-diol) metabolite from halotolerant Bacillus methylotrophicus MHC10 and its inhibitory activity towards bacterial pathogens.

PubMed

Jeyanthi, Venkadapathi; Anbu, Periasamy; Vairamani, Mariappanadar; Velusamy, Palaniyandi

2016-03-01

A halotolerant bacterial isolate-MHC10 with broad spectrum antibacterial activity against clinical pathogens was isolated from saltpans located in Tuticorin and Chennai (India). 16S rRNA gene analysis of MHC10 revealed close similarity to that of Bacillus methylotrophicus. The culture conditions of B. methylotrophicus MHC10 strain were optimized for antibacterial production using different carbon and nitrogen sources, as well as varying temperature, pH, sodium chloride (NaCl) concentrations and incubation periods. The maximum antibacterial activity of B. methylotrophicus MHC10 was attained when ZMB was optimized with 1 % (w/v) glucose, 0.1 % (w/v) soybean meal which corresponded to a C/N ratio of 38.83, temperature at 37 °C, pH 7.0 and 8 % NaCl. The activity remained stable between 72 and 96 h and then drastically decreased after 96 h. Solvent extraction followed by chromatographic purification steps led to the isolation of hydroquinone (benzene-1,4-diol). The structure of the purified compound was elucidated based on FTIR, (1)H NMR, and (13)C NMR spectroscopy. The compound exhibited efficient antibacterial activity against both Gram-positive and Gram-negative bacterial pathogens. The minimum inhibitory concentration (MIC) for Gram-positive pathogens ranged from 15.625 to 62.5 µg/mL(-1), while it was between 7.81 and 250 µg/mL(-1) for Gram-negative bacterial pathogens. This is the first report of hydroquinone produced by halotolerant B. methylotrophicus exhibiting promising antibacterial activity.

Draft Genome Sequence of an Isolate of Colletotrichum fructicola, a Causal Agent of Mango Anthracnose.

PubMed

Li, Qili; Bu, Junyan; Yu, Zhihe; Tang, Lihua; Huang, Suiping; Guo, Tangxun; Mo, Jianyou; Hsiang, Tom

2018-02-22

Here, we present a draft genome sequence of isolate 15060 of Colletotrichum fructicola , a causal agent of mango anthracnose. The final assembly consists of 1,048 scaffolds totaling 56,493,063 bp (G+C content, 53.38%) and 15,180 predicted genes. Copyright © 2018 Li et al.

A Year of Infection in the Intensive Care Unit: Prospective Whole Genome Sequencing of Bacterial Clinical Isolates Reveals Cryptic Transmissions and Novel Microbiota

PubMed Central

Roach, David J.; Burton, Joshua N.; Lee, Choli; Stackhouse, Bethany; Butler-Wu, Susan M.; Cookson, Brad T.

2015-01-01

Bacterial whole genome sequencing holds promise as a disruptive technology in clinical microbiology, but it has not yet been applied systematically or comprehensively within a clinical context. Here, over the course of one year, we performed prospective collection and whole genome sequencing of nearly all bacterial isolates obtained from a tertiary care hospital’s intensive care units (ICUs). This unbiased collection of 1,229 bacterial genomes from 391 patients enables detailed exploration of several features of clinical pathogens. A sizable fraction of isolates identified as clinically relevant corresponded to previously undescribed species: 12% of isolates assigned a species-level classification by conventional methods actually qualified as distinct, novel genomospecies on the basis of genomic similarity. Pan-genome analysis of the most frequently encountered pathogens in the collection revealed substantial variation in pan-genome size (1,420 to 20,432 genes) and the rate of gene discovery (1 to 152 genes per isolate sequenced). Surprisingly, although potential nosocomial transmission of actively surveilled pathogens was rare, 8.7% of isolates belonged to genomically related clonal lineages that were present among multiple patients, usually with overlapping hospital admissions, and were associated with clinically significant infection in 62% of patients from which they were recovered. Multi-patient clonal lineages were particularly evident in the neonatal care unit, where seven separate Staphylococcus epidermidis clonal lineages were identified, including one lineage associated with bacteremia in 5/9 neonates. Our study highlights key differences in the information made available by conventional microbiological practices versus whole genome sequencing, and motivates the further integration of microbial genome sequencing into routine clinical care. PMID:26230489

Characterization of Novel Trichoderma asperellum Isolates to Select Effective Biocontrol Agents Against Tomato Fusarium Wilt

PubMed Central

El_Komy, Mahmoud H.; Saleh, Amgad A.; Eranthodi, Anas; Molan, Younes Y.

2015-01-01

The use of novel isolates of Trichoderma with efficient antagonistic capacity against Fusarium oxysporum f. sp. lycopersici (FOL) is a promising alternative strategy to pesticides for tomato wilt management. We evaluated the antagonistic activity of 30 isolates of T. asperellum against 4 different isolates of FOL. The production of extracellular cell wall degrading enzymes of the antagonistic isolates was also measured. The random amplified polymorphic DNA (RAPD) method was applied to assess the genetic variability among the T. asperellum isolates. All of the T. asperellum isolates significantly reduced the mycelial growth of FOL isolates but the amount of growth reduction varied significantly as well. There was a correlation between the antagonistic capacity of T. asperellum isolates towards FOL and their lytic enzyme production. Isolates showing high levels of chitinase and β-1,3-glucanase activities strongly inhibited the growth of FOL isolates. RAPD analysis showed a high level of genetic variation among T. asperellum isolates. The UPGMA dendrogram revealed that T. asperellum isolates could not be grouped by their anta- gonistic behavior or lytic enzymes production. Six isolates of T. asperellum were highly antagonistic towards FOL and potentially could be used in commercial agriculture to control tomato wilt. Our results are consistent with the conclusion that understanding the genetic variation within Trichoderma isolates and their biochemical capabilities are required for the selection of effective indigenous fungal strains for the use as biocontrol agents. PMID:25774110

Bacterial Microbiota of Rice Roots: 16S-Based Taxonomic Profiling of Endophytic and Rhizospheric Diversity, Endophytes Isolation and Simplified Endophytic Community.

PubMed

Moronta-Barrios, Felix; Gionechetti, Fabrizia; Pallavicini, Alberto; Marys, Edgloris; Venturi, Vittorio

2018-02-11

Rice is currently the most important food crop in the world and we are only just beginning to study the bacterial associated microbiome. It is of importance to perform screenings of the core rice microbiota and also to develop new plant-microbe models and simplified communities for increasing our understanding about the formation and function of its microbiome. In order to begin to address this aspect, we have performed a 16S rDNA taxonomic bacterial profiling of the rhizosphere and endorhizosphere of two high-yield rice cultivars-Pionero 2010 FL and DANAC SD20A-extensively grown in Venezuela in 2014. Fifteen putative bacterial endophytes were then isolated from surface-sterilized roots and further studied in vitro and in planta . We have then performed inoculation of rice seedlings with a simplified community composed by 10 of the isolates and we have tracked them in the course of 30 days in greenhouse cultivation. The results obtained suggest that a set was able to significantly colonize together the rice endorhizospheres, indicating possible cooperation and the ability to form a stable multispecies community. This approach can be useful in the development of microbial solutions for a more sustainable rice production.

Molecular Survey of Bacterial Zoonotic Agents in Bats from the Country of Georgia (Caucasus)

PubMed Central

Osikowicz, Lynn; McKee, Clifton; Kuzmin, Ivan; Kandaurov, Andrei; Babuadze, Giorgi; Natradze, Ioseb; Imnadze, Paata; Kosoy, Michael

2017-01-01

Bats are important reservoirs for many zoonotic pathogens. However, no surveys of bacterial pathogens in bats have been performed in the Caucasus region. To understand the occurrence and distribution of bacterial infections in these mammals, 218 bats belonging to eight species collected from four regions of Georgia were examined for Bartonella, Brucella, Leptospira, and Yersinia using molecular approaches. Bartonella DNA was detected in 77 (35%) bats from all eight species and was distributed in all four regions. The prevalence ranged 6–50% per bat species. The Bartonella DNA represented 25 unique genetic variants that clustered into 21 lineages. Brucella DNA was detected in two Miniopterus schreibersii bats and in two Myotis blythii bats, all of which were from Imereti (west-central region). Leptospira DNA was detected in 25 (13%) bats that included four M. schreibersii bats and 21 M. blythii bats collected from two regions. The Leptospira sequences represented five genetic variants with one of them being closely related to the zoonotic pathogen L. interrogans (98.6% genetic identity). No Yersinia DNA was detected in the bats. Mixed infections were observed in several cases. One M. blythii bat and one M. schreibersii bat were co-infected with Bartonella, Brucella, and Leptospira; one M. blythii bat and one M. schreibersii bat were co-infected with Bartonella and Brucella; 15 M. blythii bats and three M. schreibersii bats were co-infected with Bartonella and Leptospira. Our results suggest that bats in Georgia are exposed to multiple bacterial infections. Further studies are needed to evaluate pathogenicity of these agents to bats and their zoonotic potential. PMID:28129398

Prevalence of plant beneficial and human pathogenic bacteria isolated from salad vegetables in India.

PubMed

Nithya, Angamuthu; Babu, Subramanian

2017-03-14

The study aimed at enumerating, identifying and categorizing the endophytic cultivable bacterial community in selected salad vegetables (carrot, cucumber, tomato and onion). Vegetable samples were collected from markets of two vegetable hot spot growing areas, during two different crop harvest seasons. Crude and diluted vegetable extracts were plated and the population of endophytic bacteria was assessed based on morphologically distinguishable colonies. The bacterial isolates were identified by growth in selective media, biochemical tests and 16S rRNA gene sequencing. The endophytic population was found to be comparably higher in cucumber and tomato in both of the sampling locations, whereas lower in carrot and onion. Bacterial isolates belonged to 5 classes covering 46 distinct species belonging to 19 genera. Human opportunistic pathogens were predominant in carrot and onion, whereas plant beneficial bacteria dominated in cucumber and tomato. Out of the 104 isolates, 16.25% are human pathogens and 26.5% are human opportunistic pathogens. Existence of a high population of plant beneficial bacteria was found to have suppressed the population of plant and human pathogens. There is a greater potential to study the native endophytic plant beneficial bacteria for developing them as biocontrol agents against human pathogens that are harboured by plants.

Enhancement of Population Size of a Biological Control Agent and Efficacy in Control of Bacterial Speck of Tomato through Salicylate and Ammonium Sulfate Amendments

PubMed Central

Ji, Pingsheng; Wilson, Mark

2003-01-01

Sodium salicylate and ammonium sulfate were applied to leaf surfaces along with suspensions of the biological control agents Pseudomonas syringae Cit7(pNAH7), which catabolizes salicylate, and Cit7, which does not catabolize salicylate, to determine whether enhanced biological control of bacterial speck of tomato could be achieved. Foliar amendment with salicylate alone significantly enhanced the population size and the efficacy of Cit7(pNAH7), but not of Cit7, on tomato leaves. Application of ammonium sulfate alone did not result in enhanced population size or biological control efficacy of either Cit7(pNAH7) or Cit7; however, when foliar amendments with both sodium salicylate and ammonium sulfate were applied, a trend toward further increases in population size and biological control efficacy of Cit7(pNAH7) was observed. This study demonstrates the potential of using a selective carbon source to improve the efficacy of a bacterial biological control agent in the control of a bacterial plant disease and supports previous conclusions that the growth of P. syringae in the phyllosphere is primarily carbon limited and secondarily nitrogen limited. PMID:12571060

Antibacterial Activity of Ethyl Acetate the Extract of Noni Fruit (Morinda citrifolia L.) Against Bacterial Spoilage in Fish

NASA Astrophysics Data System (ADS)

Nugraheni, E. R.; Adriani, G. R.; Munawaroh, H.

2017-04-01

Noni fruit (Morinda citrifolia L.) contains compounds that have potential as antibacterial agent. Antibacterial compounds produced noni fruit (M. citrifolia L.) can inhibit bacterial growth. This study was conducted to test the antibacterial activity of ethyl acetate extract of noni fruit (M. citrifolia L.) against spoilage bacterial in fish. Pseudomonas aeruginosa, Bacillus cereus, Escherichia coli, Klebsiella oxytoca, and Enterobacter aerogenes isolates and examine antibacterial phytochemical profile. Extraction of noni compounds was done by maceration, followed by partition with ethyl acetate to obtain the soluble and insoluble ethyl acetate fraction. Previews result show that the ethyl acetate extract had very strong activity. Extraction process continued by separation and isolation used preparative thin layer chromatography method, so that obtained five isolates and mark them as A, B, C, D and E. Antibacterial activity assay performed on isolates A, B, C, D, and E with 20 and 30% concentration. The test results showed that isolates A could not be inhibit the growth of bacteria, isolates B, C, D, and E has antibacterial activity with weak to strong inhibition. Isolate B had the greatest inhibition activity against the B. cereus, whereas isolates E had the greatest inhibition activity against P. aeroginosa. MIC (Minimum Inhibitor Concentration) and MBC (Minimum Bactericidal Concentration) test result showed that MIC and MBC values could not be determined. Analysis of compounds by TLC showed that isolate B suspected contains coumarin or flavonoids compounds that have antibacterial activity.

Brevibacillus sp. KUMAs2, a bacterial isolate for possible bioremediation of arsenic in rhizosphere.

PubMed

Mallick, Ivy; Hossain, Sk Tofajjen; Sinha, Sangram; Mukherjee, Samir Kumar

2014-09-01

Arsenic (As) contamination of soil and water has been considered as a major global environmental issue during last few decades. Among the various methods so far reported for reclamation of As contaminated rhizosphere soil, bioremediation using bacteria has been found to be most promising. An As resistant bacterial isolate Brevibacillus sp. KUMAs2 was obtained from As contaminated soil of Nadia, West Bengal, India, which could resist As(V) and As(III) a maximum of 265mM and 17mM, respectively. The strain could remove ~40 percent As under aerobic culture conditions. As resistant property in KUMAs2 was found to be plasmid-borne, which carried both As oxidizing and reducing genes. The strain could promote chilli plant growth under As contaminated soil environment by decreasing As accumulation in plant upon successful colonization in the rhizosphere, which suggests the possibility of using this isolate for successful bioremediation of As in the crop field. Copyright © 2014 Elsevier Inc. All rights reserved.

Biodegradation of the metallic carcinogen hexavalent chromium Cr(VI) by an indigenously isolated bacterial strain

PubMed Central

Mishra, Susmita

2010-01-01

Background: Hexavalent chromium [Cr(VI)], a potential mutagen and carcinogen, is regularly introduced into the environment through diverse anthropogenic activities, including electroplating, leather tanning, and pigment manufacturing. Human exposure to this toxic metal ion not only causes potential human health hazards but also affects other life forms. The World Health Organization, the International Agency for Research on Cancer, and the Environmental Protection Agency have determined that Cr(VI) compounds are known human carcinogens. The Sukinda valley in Jajpur District, Orissa, is known for its deposit of chromite ore, producing nearly 98% of the chromite ore in India and one of the prime open cast chromite ore mines in the world (CES, Orissa Newsletter). Materials and Methods: Our investigation involved microbial remediation of Cr(VI) without producing any byproduct. Bacterial cultures tolerating high concentrations of Cr were isolated from the soil sample collected from the chromite-contaminated sites of Sukinda, and their bioaccumulation properties were investigated. Strains capable of growing at 250 mg/L Cr(VI) were considered as Cr resistant. Results: The experimental investigation showed the maximum specific Cr uptake at pH 7 and temperature 30°C. At about 50 mg/L initial Cr(VI) concentrations, uptake of the selected potential strain exceeded 98% within 12 h of incubation. The bacterial isolate was identified by 16S rRNA sequencing as Brevebacterium casei. Conclusion: Results indicated promising approach for microbial remediation of effluents containing elevated levels of Cr(VI). PMID:20976016

Comparison of Asian porcine high fever disease isolates of porcine reproductive and respiratory syndrome virus to United States isolates for their ability to cause disease and secondary bacterial infection in swine

USDA-ARS?s Scientific Manuscript database

Epidemiologic data from Asian outbreaks of highly-pathogenic (HP) porcine reproductive and respiratory syndrome virus (PRRSV) suggest that disease severity was associated with both the virulence of the PRRSV isolates and secondary bacterial infections. Previous reports have indicated that U.S. isola...

Mounting resistance of uropathogens to antimicrobial agents: A retrospective study in patients with chronic bacterial prostatitis relapse.

PubMed

Stamatiou, Konstantinos; Pierris, Nikolaos

2017-07-01

Despite recent progress in the management of chronic bacterial prostatitis (CBP), many cases relapse. Increased drug resistance patterns of responsible bacteria have been proposed as the most probable causative factor. Driven by the limited number of previous studies addressing this topic, we aimed to study whether antibiotic resistance increases in patients with CBP when relapse occurs. A secondary aim of this study was to determine the resistance patterns of responsible bacteria from patients with CBP. The study material consisted of bacterial isolates from urine and/or prostatic secretions obtained from patients with CBP. Bacterial identification was performed by using the Vitek 2 Compact system and susceptibility testing was performed by disc diffusion and/or the Vitek 2 system. Interpretation of susceptibility results was based on Clinical and Laboratory Standards Institute guidelines. A total of 253 samples from patients diagnosed with CBP for the first time (group A) and 137 samples from relapsing patients with a history of CBP and previous antibiotic treatment (group B) were analyzed. A significant reduction in bacterial resistance to the less used antibiotics (TMP-SMX, tetracyclines, aminoglycosides, penicillins, and macrolides) was noted. An increase in resistance to quinolones of many bacteria that cause CBP was also noted with the increase in resistance of enterococcus strains being alarming. Comparison of the resistance profile of CBP-responsible bacteria between samples from first-time-diagnosed patients and samples from relapsing patients revealed notable differences that could be attributed to previous antibiotic treatment.

Poly-β-hydroxybutyrate and exopolysaccharide biosynthesis by bacterial isolates from pigeonpea [Cajanus cajan (L.) Millsp] root nodules.

PubMed

Fernandes, Paulo Ivan; de Oliveira, Paulo Jansen; Rumjanek, Norma Gouvêa; Xavier, Gustavo Ribeiro

2011-02-01

The bacterial strains that are able to produce biopolymers that are applied in industrial sectors present a source of renewable resources. Some microorganisms are already applied at several industrial sectors, but the prospecting of new microbes must bring microorganisms that are feasible to produce interesting biopolymers more efficiently and in cheaper conditions. Among the biopolymers applied industrially, polyhydroxybutyrate (PHB) and exopolysaccharides (EPS) stand out because of its applications, mainly in biodegradable plastic production and in food industry, respectively. In this context, the capacity of bacteria isolated from pigeonpea root nodules to produce EPS and PHB was evaluated, as well as the cultural characterization of these isolates. Among the 38 isolates evaluated, the majority presented fast growth and ability to acidify the culture media. Regarding the biopolymer production, five isolates produced more than 10 mg PHB per liter of culture medium. Six EPS producing bacteria achieved more than 200 mg EPS per liter of culture medium. Evaluating different carbon sources, the PHB productivity of the isolate 24.6b reached 69% of cell dry weight when cultured with starch as sole carbon source, and the isolate 8.1c synthesized 53% PHB in dry cell biomass and more than 1.3 g L⁻¹ of EPS when grown using xylose as sole carbon source.

Bacteriophage Amplification-Coupled Detection and Identification of Bacterial Pathogens

NASA Astrophysics Data System (ADS)

Cox, Christopher R.; Voorhees, Kent J.

Current methods of species-specific bacterial detection and identification are complex, time-consuming, and often require expensive specialized equipment and highly trained personnel. Numerous biochemical and genotypic identification methods have been applied to bacterial characterization, but all rely on tedious microbiological culturing practices and/or costly sequencing protocols which render them impractical for deployment as rapid, cost-effective point-of-care or field detection and identification methods. With a view towards addressing these shortcomings, we have exploited the evolutionarily conserved interactions between a bacteriophage (phage) and its bacterial host to develop species-specific detection methods. Phage amplification-coupled matrix assisted laser desorption time-of-flight mass spectrometry (MALDI-TOF-MS) was utilized to rapidly detect phage propagation resulting from species-specific in vitro bacterial infection. This novel signal amplification method allowed for bacterial detection and identification in as little as 2 h, and when combined with disulfide bond reduction methods developed in our laboratory to enhance MALDI-TOF-MS resolution, was observed to lower the limit of detection by several orders of magnitude over conventional spectroscopy and phage typing methods. Phage amplification has been combined with lateral flow immunochromatography (LFI) to develop rapid, easy-to-operate, portable, species-specific point-of-care (POC) detection devices. Prototype LFI detectors have been developed and characterized for Yersinia pestis and Bacillus anthracis, the etiologic agents of plague and anthrax, respectively. Comparable sensitivity and rapidity was observed when phage amplification was adapted to a species-specific handheld LFI detector, thus allowing for rapid, simple, POC bacterial detection and identification while eliminating the need for bacterial culturing or DNA isolation and amplification techniques.

Comparison of Pathogen Eradication Rate and Safety of Anti-Bacterial Agents for Bronchitis: A Network Meta-Analysis.

PubMed

Wang, Jinghua; Xu, Haiyang; Wang, Dunwei; Li, Mingxian

2017-10-01

A large number of population in both developing and developed countries are affected by bronchitis, among all the factors, bacterial infection was considered as a critical cause of acute exacerbations of chronic bronchitis. Although several anti-bacterial agents were proved to have the effect of alleviating bronchitis, their relative efficacies and potential side effects remained not clear. We are keen to compare the pathogen eradication rate and safety of anti-bacterial agents for bronchitis. Relevant studies were searched in multiple sources and data were extracted from eligible studies. Then conventional meta-analysis and network meta-analysis (NMA) were conducted to determine the relative efficacy and safety of bronchitis medications. The efficacy of bronchitis medications was determined by using the outcome of pathogen eradication, including total pathogen eradication, pathogen eradication of Haemophilus influenzae, pathogen eradication of Moraxella catarrhalis, and pathogen eradication of Streptococcus pneumoniae. In addition, safety was assessed by using the outcome of adverse effects and diarrhoea. A 27 RCTs with 9,414 participants were included in the study. Among the medications, gatifloxacin and moxifloxacin exhibited better performance than clarithromycin with respect to pathogen eradication of H. influenzae (OR = 21.37, CI: 1.22-541.28; OR = 7.43, CI: 1.79-30.50). Clarithromycin, gemifloxacin, levofloxacin, moxifloxacin, and telithromycin appeared to be more preferable than amoxicillin + clavulanate and azithromycin with respect to diarrhoea (all OR <1). The surface under the cumulative ranking curve (SUCRA) results suggested that gemifloxacin and levofloxacin had a relatively high ranking in total pathogen eradication, whereas amoxicillin + clavulanate and azithromycin exhibited relatively lower ranking with respect to adverse effects and diarrhoea. Gemifloxacin and levofloxacin are more preferable than others for lowering respiratory

Determination of physiological, taxonomic, and molecular characteristics of a cultivable arsenic-resistant bacterial community.

PubMed

Cordi, A; Pagnout, C; Devin, S; Poirel, J; Billard, P; Dollard, M A; Bauda, P

2015-09-01

A collection of 219 bacterial arsenic-resistant isolates was constituted from neutral arsenic mine drainage sediments. Isolates were grown aerobically or anaerobically during 21 days on solid DR2A medium using agar or gelan gum as gelling agent, with 7 mM As(III) or 20 mM As(V) as selective pressure. Interestingly, the sum of the different incubation conditions used (arsenic form, gelling agent, oxygen pressure) results in an overall increase of the isolate diversity. Isolated strains mainly belonged to Proteobacteria (63%), Actinobacteria (25%), and Bacteroidetes (10%). The most representative genera were Pseudomonas (20%), Acinetobacter (8%), and Serratia (15%) among the Proteobacteria; Rhodococcus (13%) and Microbacterium (5%) among Actinobacteria; and Flavobacterium (13%) among the Bacteroidetes. Isolates were screened for the presence of arsenic-related genes (arsB, ACR3(1), ACR3(2), aioA, arsM, and arrA). In this way, 106 ACR3(1)-, 74 arsB-, 22 aioA-, 14 ACR3(2)-, and one arsM-positive PCR products were obtained and sequenced. Analysis of isolate sensitivity toward metalloids (arsenite, arsenate, and antimonite) revealed correlations between taxonomy, sensitivity, and genotype. Antimonite sensitivity correlated with the presence of ACR3(1) mainly present in Bacteroidetes and Actinobacteria, and arsenite or antimonite resistance correlated with arsB gene presence. The presence of either aioA gene or several different arsenite carrier genes did not ensure a high level of arsenic resistance in the tested conditions.

Differential signatures of bacterial and mammalian IMP dehydrogenase enzymes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, R.; Evans, G.; Rotella, F.

1999-06-01

IMP dehydrogenase (IMPDH) is an essential enzyme of de novo guanine nucleotide synthesis. IMPDH inhibitors have clinical utility as antiviral, anticancer or immunosuppressive agents. The essential nature of this enzyme suggests its therapeutic applications may be extended to the development of antimicrobial agents. Bacterial IMPDH enzymes show bio- chemical and kinetic characteristics that are different than the mammalian IMPDH enzymes, suggesting IMPDH may be an attractive target for the development of antimicrobial agents. We suggest that the biochemical and kinetic differences between bacterial and mammalian enzymes are a consequence of the variance of specific, identifiable amino acid residues. Identification ofmore » these residues or combination of residues that impart this mammalian or bacterial enzyme signature is a prerequisite for the rational identification of agents that specifically target the bacterial enzyme. We used sequence alignments of IMPDH proteins to identify sequence signatures associated with bacterial or eukaryotic IMPDH enzymes. These selections were further refined to discern those likely to have a role in catalysis using information derived from the bacterial and mammalian IMPDH crystal structures and site-specific mutagenesis. Candidate bacterial sequence signatures identified by this process include regions involved in subunit interactions, the active site flap and the NAD binding region. Analysis of sequence alignments in these regions indicates a pattern of catalytic residues conserved in all enzymes and a secondary pattern of amino acid conservation associated with the major phylogenetic groups. Elucidation of the basis for this mammalian/bacterial IMPDH signature will provide insight into the catalytic mechanism of this enzyme and the foundation for the development of highly specific inhibitors.« less

Isolation and partial characterization of Streptococcus suis from clinical cases in cattle.

PubMed

Okwumabua, Ogi; Peterson, Hanna; Hsu, Hui-Min; Bochsler, Phil; Behr, Melissa

2017-03-01

Sixteen isolates of gram-positive, coccoid bacteria were obtained from clinical cases of diverse conditions in cattle and identified as Streptococcus suis using 16S ribosomal DNA gene sequencing and other bacterial identification methods. None of the isolates could be assigned to any of the known S. suis capsular types. Virulence-associated gene profiling that targeted muramidase-released protein, extracellular protein factor, suilysin, 89-kb pathogenicity island, and arginine deiminase ( arcA) genes were negative except for 1 isolate that was arcA positive. The arcA-positive isolate caused severe widespread lesions, including multiorgan suppurative and hemorrhagic inflammation in the meninges, lung, liver, spleen, lymph nodes, and serosae of heart and intestines. The other isolates were primarily associated with meningitis, bronchopneumonia, and multifocal acute necrotizing hepatitis. The isolates differed from each other by 4-6 fragments when examined by pulsed-field gel electrophoresis, indicating they are possibly related. The isolates were susceptible to ampicillin, penicillin, and tiamulin. Resistance was noted to sulfadimethoxine (93%), oxytetracycline (86%), chlortetracycline (86%), neomycin (67%), tilmicosin (47%), clindamycin (47%), enrofloxacin (33%), gentamicin (13%), florfenicol (7%), trimethoprim-sulfamethoxazole (7%), and spectinomycin (53%). Multi-drug resistance (defined as resistance to at least 1 agent in 3 or more antimicrobial classes) was detected in 67% of the isolates. The pathology observations provide evidence that S. suis may be an important pathogen of bovine calves. S. suis is an agent that clinical bacteriology laboratories should consider when dealing with cases involving cattle.

Evaluation of atoxigenic isolates of Aspergillus flavus as potential biocontrol agents for aflatoxin in maize.

PubMed

Atehnkeng, J; Ojiambo, P S; Ikotun, T; Sikora, R A; Cotty, P J; Bandyopadhyay, R

2008-10-01

Aflatoxin contamination resulting from maize infection by Aspergillus flavus is both an economic and a public health concern. Therefore, strategies for controlling aflatoxin contamination in maize are being investigated. The abilities of eleven naturally occurring atoxigenic isolates in Nigeria to reduce aflatoxin contamination in maize were evaluated in grain competition experiments and in field studies during the 2005 and 2006 growing seasons. Treatments consisted of inoculation of either grains in vials or ears at mid-silking stage in field plots, with the toxigenic isolate (La3228) or atoxigenic isolate alone and co-inoculation of each atoxigenic isolate and La3328. Aflatoxin B(1) + B(2) concentrations were significantly (p < 0.05) lower in the co-inoculation treatments compared with the treatment in which the aflatoxin-producing isolate La3228 was inoculated alone. Relative levels of aflatoxin B(1) + B(2) reduction ranged from 70.1% to 99.9%. Among the atoxigenics, two isolates from Lafia, La3279 and La3303, were most effective at reducing aflatoxin B(1) + B(2) concentrations in both laboratory and field trials. These two isolates have potential value as agents for the biocontrol of aflatoxin contamination in maize. Because these isolates are endemic to West Africa, they are both more likely than introduced isolates to be well adapted to West African environments and to meet regulatory concerns over their use throughout that region.

Microbiome analysis and bacterial isolation from Lejía Lake soil in Atacama Desert.

PubMed

Mandakovic, Dinka; Maldonado, Jonathan; Pulgar, Rodrigo; Cabrera, Pablo; Gaete, Alexis; Urtuvia, Viviana; Seeger, Michael; Cambiazo, Verónica; González, Mauricio

2018-07-01

As a consequence of the severe climatic change affecting our entire world, many lakes in the Andes Cordillera are likely to disappear within a few decades. One of these lakes is Lejía Lake, located in the central Atacama Desert. The objectives of this study were: (1) to characterize the bacterial community from Lejía Lake shore soil (LLS) using 16S rRNA sequencing and (2) to test a culture-based approach using a soil extract medium (SEM) to recover soil bacteria. This extreme ecosystem was dominated by three phyla: Bacteroidetes, Proteobacteria, and Firmicutes with 29.2, 28.2 and 28.1% of the relative abundance, respectively. Using SEM, we recovered 7.4% of the operational taxonomic units from LLS, all of which belonged to the same three dominant phyla from LLS (6.9% of Bacteroidetes, 77.6% of Proteobacteria, and 15.3% of Firmicutes). In addition, we used SEM to recover isolates from LLS and supplemented the culture medium with increasing salt concentrations to isolate microbial representatives of salt tolerance (Halomonas spp.). The results of this study complement the list of microbial taxa diversity from the Atacama Desert and assess a pipeline to isolate selective bacteria that could represent useful elements for biotechnological approaches.

[Effect of penicillin and the habitat medium in the body of bacterial carriers on the intercellular bonds in populations of the meningococcus and pertussis microbe].

PubMed

Vysotskiĭ, V V; Smirnova-Mutusheva, M A; Efimova, O G; Bakulina, N A

1983-04-01

The relationship of the bacterial cells in populations and their adhesion activity is at present one of the research priorities in microbiological studies. The stimulating effect of penicillin on the development of morphologically different intercellular bonds (IB) in populations of the pertussis causative agent and first of all derivatives or evaginates of the cell wall membranes was observed. Morphologically similar systems and polytubular IB were detected in populations of meningococcal strains isolated from carriers having no signs of the disease. Correlation between the after-effect of penicillin and the presence of the causative agent in bacterial carriers was shown. Unknown systems of interlacing tubular structures not directly bound with the cells, the walls of which were single contour membranes were determined in the meningococcal populations treated with penicillin. IB were observed in the population in the form of transpopulation cords. Morphologically different IB playing the role of specialized organelles might be considered as factors of the functional unity of the bacterial population as a multicellular system.

Isolation of high-salinity-tolerant bacterial strains, Enterobacter sp., Serratia sp., Yersinia sp., for nitrification and aerobic denitrification under cyanogenic conditions.

PubMed

Mpongwana, N; Ntwampe, S K O; Mekuto, L; Akinpelu, E A; Dyantyi, S; Mpentshu, Y

2016-01-01

Cyanides (CN(-)) and soluble salts could potentially inhibit biological processes in wastewater treatment plants (WWTPs), such as nitrification and denitrification. Cyanide in wastewater can alter metabolic functions of microbial populations in WWTPs, thus significantly inhibiting nitrifier and denitrifier metabolic processes, rendering the water treatment processes ineffective. In this study, bacterial isolates that are tolerant to high salinity conditions, which are capable of nitrification and aerobic denitrification under cyanogenic conditions, were isolated from a poultry slaughterhouse effluent. Three of the bacterial isolates were found to be able to oxidise NH(4)-N in the presence of 65.91 mg/L of free cyanide (CN(-)) under saline conditions, i.e. 4.5% (w/v) NaCl. The isolates I, H and G, were identified as Enterobacter sp., Yersinia sp. and Serratia sp., respectively. Results showed that 81% (I), 71% (G) and 75% (H) of 400 mg/L NH(4)-N was biodegraded (nitrification) within 72 h, with the rates of biodegradation being suitably described by first order reactions, with rate constants being: 4.19 h(-1) (I), 4.21 h(-1) (H) and 3.79 h(-1) (G), respectively, with correlation coefficients ranging between 0.82 and 0.89. Chemical oxygen demand (COD) removal rates were 38% (I), 42% (H) and 48% (G), over a period of 168 h with COD reduction being highest at near neutral pH.

Bacterial communities associated with healthy and Acropora white syndrome-affected corals from American Samoa

USGS Publications Warehouse

Wilson, Bryan; Aeby, Greta S.; Work, Thierry M.; Bourne, David G.

2012-01-01

Acropora white syndrome (AWS) is characterized by rapid tissue loss revealing the white underlying skeleton and affects corals worldwide; however, reports of causal agents are conflicting. Samples were collected from healthy and diseased corals and seawater around American Samoa and bacteria associated with AWS characterized using both culture-dependent and culture-independent methods, from coral mucus and tissue slurries, respectively. Bacterial 16S rRNA gene clone libraries derived from coral tissue were dominated by the Gammaproteobacteria, and Jaccard's distances calculated between the clone libraries showed that those from diseased corals were more similar to each other than to those from healthy corals. 16S rRNA genes from 78 culturable coral mucus isolates also revealed a distinct partitioning of bacterial genera into healthy and diseased corals. Isolates identified as Vibrionaceae were further characterized by multilocus sequence typing, revealing that whilst several Vibrio spp. were found to be associated with AWS lesions, a recently described species, Vibrio owensii, was prevalent amongst cultured Vibrio isolates. Unaffected tissues from corals with AWS had a different microbiota than normal Acropora as found by others. Determining whether a microbial shift occurs prior to disease outbreaks will be a useful avenue of pursuit and could be helpful in detecting prodromal signs of coral disease prior to manifestation of lesions.

Characterization and competitive ability of non-aflatoxigenic Aspergillus flavus isolated from the maize agro-ecosystem in Argentina as potential aflatoxin biocontrol agents.

PubMed

Alaniz Zanon, María Silvina; Clemente, María Paz; Chulze, Sofía Noemí

2018-07-20

Aspergillus flavus is an opportunistic pathogen and may produce aflatoxins in maize, one of the most important crops in Argentina. A promising strategy to reduce aflatoxin accumulation is the biological control based on competitive exclusion. In order to select potential biocontrol agents among isolates from the maize growing region in Argentina, a total of 512 A. flavus strains were isolated from maize kernels and soil samples. Thirty-six per cent of the isolates from maize kernels did not produce detectable levels of aflatoxins, while 73% of the isolates from soil were characterized as non-aflatoxin producers. Forty percent and 49% of the isolates from maize kernels and soil samples, respectively, were not producers of cyclopiazonic acid (CPA). Sclerotia morphology was evaluated using Czapek Dox media. Eighty-six per cent of the isolates from maize kernels and 85% of the isolates from soil samples were L sclerotia morphotype (average diameter > 400 μm). The remaining isolates did not produce sclerotia. All isolates had MAT 1-1 idiomorph. The competitive ability of 9 non aflatoxigenic strains, 4 CPA(+) and 5 CPA(-), was evaluated in co-inoculations of maize kernels with an aflatoxigenic strain. All evaluated strains significantly (p < 0.05) reduced aflatoxin contamination in maize kernels. The aflatoxin B 1 (AFB 1 ) reduction ranged from 6 to 60%. The strain A. flavus ARG5/30 isolated from maize kernels would be a good candidate as a potential biocontrol agent to be used in maize, since it was characterized as neither aflatoxin nor CPA producer, morphotype L, MAT 1-1 idiomorph, and reduced AFB 1 content in maize kernels by 59%. This study showed the competitive ability of potential aflatoxin biocontrol agents to be evaluated under field trials in a maize agro-ecosystem in Argentina. Copyright © 2018 Elsevier B.V. All rights reserved.

Isolation of Dickeya dadantii strains from potato disease and biocontrol by their bacteriophages.

PubMed

Soleimani-Delfan, Abbas; Etemadifar, Zahra; Emtiazi, Giti; Bouzari, Majid

2015-01-01

One of the most economically important bacterial pathogens of plants and plant products is Dickeya dadantii. This bacterium causes soft rot disease in tubers and other parts of the potato and other plants of the Solanaceae family. The application of restricted host range bacteriophages as biocontrol agents has recently gained widespread interest. This study purposed to isolate the infectious agent of the potato and evaluate its biocontrol by bacteriophages. Two phytopathogenic strains were isolated from infected potatoes, identified based on biochemical and 16S rRNA gene sequencing, and submitted to GenBank as D. dadantii strain pis3 (accession no. HQ423668) and D. dadantii strain sip4 (accession no. HQ423669). Their bacteriophages were isolated from Caspian Sea water by enriching the water filtrate with D. dadantii strains as hosts using spot or overlay methods. On the basis of morphotypes, the isolated bacteriophages were identified as members of the Myoviridae and Siphoviridae families and could inhibit the growth of antibiotic resistant D. dadantii strains in culture medium. Moreover, in Dickeya infected plants treated with bacteriophage, no disease progression was detected. No significant difference was seen between phage-treated and control plants. Thus, isolated bacteriophages can be suggested for the biocontrol of plant disease caused by Dickeya strains.

Isolation, Characterization and Identification of Environmental Bacterial Isolates with Screening for Antagonism Against Three Bacterial Targets

DTIC Science & Technology

2017-04-01

treatments. This report summarizes work conducted to identify microorganisms that exhibit narrow-spectrum activity through the secretion of...induced activity against three target strains of interest to the DoD: Bacillus anthracis Sterne, Staphylococcus aureus and Pseudomonas aeruginosa. The...percentage of environmental isolates that demonstrated activity against Bacillus anthracis Sterne was 15% (9 of 62 isolates screened), while 2% of

Multiple reservoirs contribute to intraoperative bacterial transmission.

PubMed

Loftus, Randy W; Brown, Jeremiah R; Koff, Matthew D; Reddy, Sundara; Heard, Stephen O; Patel, Hetal M; Fernandez, Patrick G; Beach, Michael L; Corwin, Howard L; Jensen, Jens T; Kispert, David; Huysman, Bridget; Dodds, Thomas M; Ruoff, Kathryn L; Yeager, Mark P

2012-06-01

Intraoperative stopcock contamination is a frequent event associated with increased patient mortality. In the current study we examined the relative contributions of anesthesia provider hands, the patient, and the patient environment to stopcock contamination. Our secondary aims were to identify risk factors for stopcock contamination and to examine the prior association of stopcock contamination with 30-day postoperative infection and mortality. Additional microbiological analyses were completed to determine the prevalence of bacterial pathogens within intraoperative bacterial reservoirs. Pulsed-field gel electrophoresis was used to assess the contribution of reservoir bacterial pathogens to 30-day postoperative infections. In a multicenter study, stopcock transmission events were observed in 274 operating rooms, with the first and second cases of the day in each operating room studied in series to identify within- and between-case transmission events. Reservoir bacterial cultures were obtained and compared with stopcock set isolates to determine the origin of stopcock contamination. Between-case transmission was defined by the isolation of 1 or more bacterial isolates from the stopcock set of a subsequent case (case 2) that were identical to reservoir isolates from the preceding case (case 1). Within-case transmission was defined by the isolation of 1 or more bacterial isolates from a stopcock set that were identical to bacterial reservoirs from the same case. Bacterial pathogens within these reservoirs were identified, and their potential contribution to postoperative infections was evaluated. All patients were followed for 30 days postoperatively for the development of infection and all-cause mortality. Stopcock contamination was detected in 23% (126 out of 548) of cases with 14 between-case and 30 within-case transmission events confirmed. All 3 reservoirs contributed to between-case (64% environment, 14% patient, and 21% provider) and within-case (47

Effect of red clay on diesel bioremediation and soil bacterial community.

PubMed

Jung, Jaejoon; Choi, Sungjong; Hong, Hyerim; Sung, Jung-Suk; Park, Woojun

2014-08-01

Red clay is a type of soil, the red color of which results from the presence of iron oxide. It is considered an eco-friendly material, with many industrial, cosmetic, and architectural uses. A patented method was applied to red clay in order to change its chemical composition and mineral bioavailability. The resulting product was designated processed red clay. This study evaluates the novel use of red clay and processed red clay as biostimulation agents in diesel-contaminated soils. Diesel biodegradation was enhanced in the presence of red clay and processed red clay by 4.9- and 6.7-fold, respectively, and the number of culturable bacterial cells was correlated with the amount of diesel biodegradation. The growth of Acinetobacter oleivorans DR1, Pseudomonas putida KT2440, and Cupriavidus necator was promoted by both types of red clays. Culture-independent community analysis determined via barcoded pyrosequencing indicated that Nocardioidaceae, Xanthomonadaceae, Pseudomonadaceae, and Caulobacteraceae were enriched by diesel contamination. Bacterial strain isolation from naphthalene- and liquid paraffin-amended media was affiliated with enriched taxa based on 16S rRNA gene sequence identity. We suggest that the biostimulating mechanism of red clay and processed red clay is able to support bacterial growth without apparent selection for specific bacterial species.

[Revised Japanese guidelines for the clinical management of bacterial meningitis].

PubMed

Ishikawa, Harumi; Kamei, Satoshi

2014-01-01

Improvement of outcomes represents the most important problem in the treatment of bacterial meningitis. To achieve such improvement, revision of the guidelines for the clinical management of bacterial meningitis in Japan has been carried out, and these revised Japanese guidelines will soon be published. The choice of specific antimicrobial agents for initial treatment in bacterial meningitis is influenced by a number of factors, including patient age, systemic symptoms, and local patterns of bacterial resistance. In the revised Japanese guidelines, antimicrobial agents based on current knowledge of the epidemiology in Japan are recommended. Bacterial meningitis is a medical emergency, and patients with this disease require immediate medical assessment and appropriate treatment. Rapid diagnosis and treatment of bacterial meningitis reduces mortality and neurological sequelae. We describe the revised Japanese guidelines for the clinical management of bacterial meningitis 2014, with a focus on adults.

Virulence Factors of Escherichia coli Isolated From Female Reproductive Tract Infections and Neonatal Sepsis

PubMed Central

Cook, Susan W.; Hammill, Hunter A.

2001-01-01

Objective: The presence of enterobacteria such as Escherichia coli in the vagina of normal women is not synonymous with infection. However, vaginal E. coli may also cause symptomatic infections. We examined bacterial virulenceproperties that may promote symptomatic female reproductive tract infections (RTI) and neonatal sepsis. Methods: E. coli isolated as the causative agent from cases of vaginitis (n = 50), tubo-ovarian abscess (n = 45) and neonatal sepsis (n = 45) was examined for selected phenotypic and genetic virulence properties. Results were compared with the frequency of the same properties among fecal E. coli not associated with disease. Results: A significantly greater proportion of infection E. coli exhibited D-mannose resistant hemagglutination compared with fecal E. coli (p < 0.01). This adherence phenotype was associated with the presence of P fimbriae (pap) genes which were also significantly more prevalent among isolates from all three infection sites (p < 0.01). The majority of pap+ isolates contained the papG3 allele (Class II) regardless of infection type. Increased frequency of Type 1C genes among vaginitis and abscess isolates was also noted. No significant differences in frequency of other bacterial adherence genes, fim, sfa, uca (gaf) or dra were observed. E. coli associated with vaginitis was significantly more likely to be hemolytic ( HIy+) than were fecal isolates (p < 0.05). The HIy+ phenotype was also more prevalent among tubo-ovarian abscess and neonatal sepsis isolates (p < 0.08). Conclusions: E. coli isolated from female RTI and neonatal sepses possess unique properties that may enhance their virulence. These properties are similar to those associated with other E. coli extra-intestinal infections, indicating that strategies such as vaccination or bacterial interference that may be developed against urinary tract infections (UTI) and other E. coli extra-intestinal infections may also prevent selected female RTI. PMID:11916176

Modeling bacterial contamination of fuel ethanol fermentation.

PubMed

Bischoff, Kenneth M; Liu, Siqing; Leathers, Timothy D; Worthington, Ronald E; Rich, Joseph O

2009-05-01

The emergence of antibiotic-resistant bacteria may limit the effectiveness of antibiotics to treat bacterial contamination in fuel ethanol plants, and therefore, new antibacterial intervention methods and tools to test their application are needed. Using shake-flask cultures of Saccharomyces cerevisiae grown on saccharified corn mash and strains of lactic acid bacteria isolated from a dry-grind ethanol facility, a simple model to simulate bacterial contamination and infection was developed. Challenging the model with 10(8) CFU/mL Lactobacillus fermentum decreased ethanol yield by 27% and increased residual glucose from 6.2 to 45.5 g/L. The magnitude of the effect was proportional to the initial bacterial load, with 10(5) CFU/mL L. fermentum still producing an 8% decrease in ethanol and a 3.2-fold increase in residual glucose. Infection was also dependent on the bacterial species used to challenge the fermentation, as neither L. delbrueckii ATCC 4797 nor L. amylovorus 0315-7B produced a significant decrease in ethanol when inoculated at a density of 10(8) CFU/mL. In the shake-flask model, treatment with 2 microg/mL virginiamycin mitigated the infection when challenged with a susceptible strain of L. fermentum (MIC for virginiamycin < or =2 ppm), but treatment was ineffective at treating infection by a resistant strain of L. fermentum (MIC = 16 ppm). The model may find application in developing new antibacterial agents and management practices for use in controlling contamination in the fuel ethanol industry. Copyright 2008 Wiley Periodicals, Inc.

Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent.

PubMed

Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

2016-01-01

Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China's Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent.

Cultured bacterial diversity and human impact on alpine glacier cryoconite.

PubMed

Lee, Yung Mi; Kim, So-Yeon; Jung, Jia; Kim, Eun Hye; Cho, Kyeung Hee; Schinner, Franz; Margesin, Rosa; Hong, Soon Gyu; Lee, Hong Kum

2011-06-01

The anthropogenic effect on the microbial communities in alpine glacier cryoconites was investigated by cultivation and physiological characterization of bacteria from six cryoconite samples taken at sites with different amounts of human impact. Two hundred and forty seven bacterial isolates were included in Actinobacteria (9%, particularly Arthrobacter), Bacteroidetes (14%, particularly Olleya), Firmicutes (0.8%), Alphaproteobacteria (2%), Betaproteobacteria (16%, particularly Janthinobacterium), and Gammaproteobacteria (59%, particularly Pseudomonas). Among them, isolates of Arthrobacter were detected only in samples from sites with no human impact, while isolates affiliated with Enterobacteriaceae were detected only in samples from sites with strong human impact. Bacterial isolates included in Actinobacteria and Bacteroidetes were frequently isolated from pristine sites and showed low maximum growth temperature and enzyme secretion. Bacterial isolates included in Gammaproteobacteria were more frequently isolated from sites with stronger human impact and showed high maximum growth temperature and enzyme secretion. Ecotypic differences were not evident among isolates of Janthinobacterium lividum, Pseudomonas fluorescens, and Pseudomonas veronii, which were frequently isolated from sites with different degrees of anthropogenic effect.

Control of biofouling by xanthine oxidase on seawater reverse osmosis membranes from a desalination plant: enzyme production and screening of bacterial isolates from the full-scale plant.

PubMed

Nagaraj, V; Skillman, L; Li, D; Xie, Z; Ho, G

2017-07-01

Control of biofouling on seawater reverse osmosis (SWRO) membranes is a major challenge as treatments can be expensive, damage the membrane material and often biocides do not remove the polymers in which bacteria are embedded. Biological control has been largely ignored for biofouling control. The objective of this study was to demonstrate the effectiveness of xanthine oxidase enzyme against complex fouling communities and then identify naturally occurring bacterial strains that produce the free radical generating enzyme. Initially, 64 bacterial strains were isolated from different locations of the Perth Seawater Desalination Plant. In our preceding study, 25/64 isolates were selected from the culture collection as models for biofouling studies, based on their prevalence in comparison to the genomic bacterial community. In this study, screening of these model strains was performed using a nitroblue tetrazolium assay in the presence of hypoxanthine as substrate. Enzyme activity was measured by absorbance. Nine of 25 strains tested positive for xanthine oxidase production, of which Exiguobacterium from sand filters and Microbacterium from RO membranes exhibited significant levels of enzyme production. Other genera that produced xanthine oxidase were Marinomonas, Pseudomonas, Bacillus, Pseudoalteromonas and Staphylococcus. Strain variations were observed between members of the genera Microbacterium and Bacillus. Xanthine oxidase, an oxidoreductase enzyme that generates reactive oxygen species, is endogenously produced by many bacterial species. In this study, production of the enzyme by bacterial isolates from a full-scale desalination plant was investigated for potential use as biological control of membrane fouling in seawater desalination. We have previously demonstrated that free radicals generated by a commercially available xanthine oxidase in the presence of a hypoxanthine substrate, effectively dispersed biofilm polysaccharides on industrially fouled membranes

Screening of bacterial antagonists for biological control of Phytophthora blight of pepper.

PubMed

Rajkumar, M; Lee, Wang Hyu; Lee, Kui Jae

2005-01-01

The aim of this study was to assess the potential of bacterial antagonists to control Phytophthora blight of pepper caused by P. capsici using different screening methods. Among a collection of fluorescent pseudomonas isolated from the rhizosphere of pepper, twelve isolates were initially selected based on dual culture assay on potato dextrose agar and corn meal agar. Further, these twelve isolates were screened for the reduction of disease severity caused by P. capsici using detached leaves and seedling assay. Most of the antagonists showed varying levels of antagonism against P. capsici in both detached leaves and seedlings assay. In addition, few isolates increased shoot and root length of pepper in seedling assays. Among them, isolate PS119 showing highest ability to reduce the disease severity in the in vitro seedling assay was found to be the most efficient antagonists against P. capsici in the in vivo biological control tests. These results indicate that the in vitro seedling assay can be used as a rapid and more accurate technique for the selection of promising biocontrol agents against P. capsici. ((c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

Newly Isolated Bacteriophages from the Podoviridae, Siphoviridae, and Myoviridae Families Have Variable Effects on Putative Novel Dickeya spp.

PubMed

Alič, Špela; Naglič, Tina; Tušek-Žnidarič, Magda; Ravnikar, Maja; Rački, Nejc; Peterka, Matjaž; Dreo, Tanja

2017-01-01

and alkaline pH. Furthermore, the stability of the tested bacteriophage was also connected to the incubation medium and bacteriophage concentration at certain pH values. Finally, the emergence of bacteriophage-resistant bacterial colonies is highly connected to the concentration of bacteriophages in the bacterial environment. This is the first report on bacteriophages against Dickeya from the Podoviridae family to expand on potential bacteriophages to include in bacteriophage cocktails as biocontrol agents. Some of these bacteriophage isolates also showed activity against Dickeya solani , an aggressive strain that causes the soft rot of potatoes, which indicates their broad potential as biocontrol agents.

Newly Isolated Bacteriophages from the Podoviridae, Siphoviridae, and Myoviridae Families Have Variable Effects on Putative Novel Dickeya spp.

PubMed Central

Alič, Špela; Naglič, Tina; Tušek-Žnidarič, Magda; Ravnikar, Maja; Rački, Nejc; Peterka, Matjaž; Dreo, Tanja

2017-01-01

alkaline pH. Furthermore, the stability of the tested bacteriophage was also connected to the incubation medium and bacteriophage concentration at certain pH values. Finally, the emergence of bacteriophage-resistant bacterial colonies is highly connected to the concentration of bacteriophages in the bacterial environment. This is the first report on bacteriophages against Dickeya from the Podoviridae family to expand on potential bacteriophages to include in bacteriophage cocktails as biocontrol agents. Some of these bacteriophage isolates also showed activity against Dickeya solani, an aggressive strain that causes the soft rot of potatoes, which indicates their broad potential as biocontrol agents. PMID:29033917

Community acquired bacterial pneumonia: aetiology, laboratory detection and antibiotic susceptibility pattern.

PubMed

Akter, Sonia; Shamsuzzaman, S M; Jahan, Ferdush

2014-08-01

This cross sectional study was conducted to identify the common bacterial causes of community acquired pneumonia (CAP) from sputum and blood by culture and polymerase chain reaction (PCR) and to evaluate the effectiveness of these tests. A total of 105 sputum and blood samples were collected from patients with pneumonia on clinical suspicion. Common causative bacterial agents of pneumonia were detected by Gram staining, cultures, biochemical tests and PCR. Among 55 sputum culture positive cases, a majority (61.82%) of the patients were in the age group between 21-50 years and the ratio between male and female was 2.5:1. Most (61.90%) of the cases were from the lower socio-economic group. Out of 105 samples, 23 (37.12%) were positive by Gram stain, 29 (27.62%) yielded growth in culture media and 37 (35.24%) were positive by PCR for Streptococcus pneumoniae and Haemophilus influenzae. Streptococcus pneumoniae was the most common aetiological agent (19.05%) followed by Klebsiella pneumoniae (13.33%), Haemophilus influenzae (8.57%) and Pseudomonas aeruginosa (5.71%). Multiplex PCR is a useful technique for rapid diagnosis of bacterial causes of pneumonia directly from sputum and blood. Considering culture as a gold standard, the sensitivity of PCR was 96.55% and specificity was 88.15%. More than 80% of Streptococcus pneumoniae isolates were found to be sensitive to ampicillin, amoxycillinclavulanate, and ceftriaxone. Susceptibilities to other antimicrobials ranged from 65% for azithromycin to 70% for levofloxacin. On the other hand, the Gram negative organisms were more sensitive to meropenem, ceftriaxone, amoxycillin-clavulanate and amikacin.

Marine Isolates of Trichoderma spp. as Potential Halotolerant Agents of Biological Control for Arid-Zone Agriculture ▿ †

PubMed Central

Gal-Hemed, Inbal; Atanasova, Lea; Komon-Zelazowska, Monika; Druzhinina, Irina S.; Viterbo, Ada; Yarden, Oded

2011-01-01

The scarcity of fresh water in the Mediterranean region necessitates the search for halotolerant agents of biological control of plant diseases that can be applied in arid-zone agriculture irrigated with saline water. Among 29 Trichoderma strains previously isolated from Mediterranean Psammocinia sp. sponges, the greatest number of isolates belong to the Trichoderma longibrachiatum-Hypocrea orientalis species pair (9), H. atroviridis/T. atroviride (9), and T. harzianum species complex (7), all of which are known for high mycoparasitic potential. In addition, one isolate of T. asperelloides and two putative new species, Trichoderma sp. O.Y. 14707 and O.Y. 2407, from Longibrachiatum and Strictipilosa clades, respectively, have been identified. In vitro salinity assays showed that the ability to tolerate increasing osmotic pressure (halotolerance) is a strain- or clade-specific property rather than a feature of a species. Only a few isolates were found to be sensitive to increased salinity, while others either were halotolerant or even demonstrated improved growth in increasingly saline conditions. In vitro antibiosis assays revealed strong antagonistic activity toward phytopathogens due to the production of both soluble and volatile metabolites. Two marine-derived Trichoderma isolates, identified as T. atroviride and T. asperelloides, respectively, effectively reduced Rhizoctonia solani damping-off disease on beans and also induced defense responses in cucumber seedlings against Pseudomonas syringae pv. lachrimans. This is the first inclusive evaluation of marine fungi as potential biocontrol agents. PMID:21666030

Optimization of Culture Parameters for Maximum Polyhydroxybutyrate Production by Selected Bacterial Strains Isolated from Rhizospheric Soils.

PubMed

Lathwal, Priyanka; Nehra, Kiran; Singh, Manpreet; Jamdagni, Pragati; Rana, Jogender S

2015-01-01

The enormous applications of conventional non-biodegradable plastics have led towards their increased usage and accumulation in the environment. This has become one of the major causes of global environmental concern in the present century. Polyhydroxybutyrate (PHB), a biodegradable plastic is known to have properties similar to conventional plastics, thus exhibiting a potential for replacing conventional non-degradable plastics. In the present study, a total of 303 different bacterial isolates were obtained from soil samples collected from the rhizospheric area of three crops, viz., wheat, mustard and sugarcane. All the isolates were screened for PHB (Poly-3-hydroxy butyric acid) production using Sudan Black staining method, and 194 isolates were found to be PHB positive. Based upon the amount of PHB produced, the isolates were divided into three categories: high, medium and low producers. Representative isolates from each category were selected for biochemical characterization; and for optimization of various culture parameters (carbon source, nitrogen source, C/N ratio, different pH, temperature and incubation time periods) for maximizing PHB accumulation. The highest PHB yield was obtained when the culture medium was supplemented with glucose as the carbon source, ammonium sulphate at a concentration of 1.0 g/l as the nitrogen source, and by maintaining the C/N ratio of the medium as 20:1. The physical growth parameters which supported maximum PHB accumulation included a pH of 7.0, and an incubation temperature of 30 degrees C for a period of 48 h. A few isolates exhibited high PHB accumulation under optimized conditions, thus showing a potential for their industrial exploitation.

Prevalence of MDR pathogens of bacterial meningitis in Egypt and new synergistic antibiotic combinations.

PubMed

Abdelkader, Mona M; Aboshanab, Khaled M; El-Ashry, Marwa A; Aboulwafa, Mohammad M

2017-01-01

The aim of this study was identifying bacterial pathogens involved in meningitis, studying their antibiotic resistance profiles, investigating the antibiotic resistance genes as well as evaluating the use of various antibiotic combinations. Antibiotic susceptibility tests were evaluated according to CLSI guidelines. Antibiotic combinations were evaluated by calculating the Fractional Inhibitory Concentration (FIC) index. A total of 71 bacterial isolates were recovered from 68 culture positive CSF specimens. Sixty five of these isolates (91.5%) were recovered from single infection specimens, while 6 isolates (8.4%) were recovered from mixed infection specimens. Out of the 71 recovered isolates, 48 (67.6%) were Gram-positive, and 23 (32.4%) were Gram-negative. Thirty one of the Gram positive isolates were S. pneumoniae (64.6%, n = 48). Out of the recovered 71 isolates; 26 (36.6%) were multidrug-resistant (MDR) isolates of which, 18 (69.2%) were Gram-negative and 8 (30.8%) were Gram-positive. All MDR isolates (100%) showed resistance to penicillin and ampicillin, however, they showed lower resistance to meropenem (50%), levofloxacin (50%), amikacin (48%), pipercillin-tazobactam (45.8%). Most common antibiotic resistance genes were investigated including: tem (21.1%), shv (15.8%), ctx-m (15.8%) coding for TEM-, SHV, CTX-M extended-spectrum beta-lactamases (ESBLs), respectively; aac(6')-I b(26.3%) coding for aminoglycoside 6'-N-acetyltransferase type Ib ciprofloxacin resistant variant; and qnrA (5.3%) gene coding for quinolone resistance. The DNA sequences of the respective resistance genes of some selected isolates were PCR amplified, analyzed and submitted to the GenBank database under the accession numbers, KX214665, KX214664, KX214663, KX214662, respectively. The FIC values for ampicillin/sulbactam plus cefepime showed either additive or synergistic effect against ten tested Gram-negative MDR isolates, while doxycycline plus levofloxacin combination revealed

Genomic characterization of key bacteriophages to formulate the potential biocontrol agent to combat enteric pathogenic bacteria.

PubMed

Parmar, Krupa M; Dafale, Nishant A; Tikariha, Hitesh; Purohit, Hemant J

2018-05-01

Combating bacterial pathogens has become a global concern especially when the antibiotics and chemical agents are failing to control the spread due to its resistance. Bacteriophages act as a safe biocontrol agent by selectively lysing the bacterial pathogens without affecting the natural beneficial microflora. The present study describes the screening of prominent enteric pathogens NDK1, NDK2, NDK3, and NDK4 (Escherichia, Klebsiella, Enterobacter, and Serratia) mostly observed in domestic wastewater; against which KNP1, KNP2, KNP3, and KNP4 phages were isolated. To analyze their potential role in eradicating enteric pathogens and toxicity issue, these bacteriophages were sequenced using next-generation sequencing and characterized based on its genomic content. The isolated bacteriophages were homologous to Escherichia phage (KNP1), Klebsiella phage (KNP2), Enterobacter phage (KNP3), Serratia phage (KNP4), and belonged to Myoviridae family of Caudovirales except for the unclassified KNP4 phage. Draft genome analysis revealed the presence of lytic enzymes such as holing and lysozyme in KNP1 phage, endolysin in KNP2 phage, and endopeptidase with holin in KNP3 phage. The absence of any lysogenic and virulent genes makes this bacteriophage suitable candidate for preparation of phage cocktail to combat the pathogens present in wastewater. However, KNP4 contained a virulent gene rendering it unsuitable to be used as a biocontrol agent. These findings make the phages (KNP1-KNP3) as a promising alternative for the biocontrol of pathogens in wastewater which is the main culprit to spread these dominated pathogens in different natural water bodies. This study also necessitates for genomic screening of bacteriophages for lysogenic and virulence genes prior to its use as a biocontrol agent.

Common causes of vaginal infections and antibiotic susceptibility of aerobic bacterial isolates in women of reproductive age attending at Felegehiwot Referral Hospital, Ethiopia: a cross sectional study.

PubMed

Mulu, Wondemagegn; Yimer, Mulat; Zenebe, Yohannes; Abera, Bayeh

2015-05-13

Bacterial vaginosis, candidal, trichomonal and Gonococcal vaginal infections are a major health problems associated with gynecologic complications and increase in replication, shedding and transmission of HIV and other STIs in women of reproductive age. The study aimed at determining the prevalence of common vaginal infections and antimicrobial susceptibility profiles of aerobic bacterial isolates in women of reproductive age, attending Felegehiwot referral Hospital. A hospital based cross sectional study was conducted from May to November, 2013. Simple random sampling technique was used. Demographic variables were collected using a structured questionnaire. Clinical data were collected by physicians. Two vaginal swab specimens were collected from each participant. Wet mount and Gram staining were carried out to identify motile T.vaginalis, budding yeast and clue cells. All vaginal specimens were cultured for aerobic bacterial isolates using standard microbiology methods. Antimicrobial susceptibility was performed using disc diffusion technique as per the standard by Kirby-Bauer method. The results were analyzed using descriptive, chi-square and fisher's exact test as appropriate. A total of 409 women in reproductive age (15 - 49 years) participated in the study. The median age of the women was 28 years. Overall, 63 (15.4 %) of women had vaginal infections. The proportion of vaginal infection was higher in non-pregnant (17.3 %) than pregnant women (13.3 %) (P = 0.002). The most common identified vaginal infections were candidiasis (8.3 %) and bacterial vaginosis (2.8 %) followed by trichomoniasis (2.1 %). The isolation rate of N. gonorrhoeae and group B Streptococcus colonization was 4 (1 %) and 6 (1.2 %), respectively. Bacterial vaginosis was higher in non-pregnant (5.6 %) than pregnant women (0.5 %) (P = 0.002). Religion, age, living in rural area and having lower abdominal pain were significantly associated with bacterial vaginosis and

Novel components of leaf bacterial communities of field-grown tomato plants and their potential for plant growth promotion and biocontrol of tomato diseases.

PubMed

Romero, Fernando M; Marina, María; Pieckenstain, Fernando L

2016-04-01

This work aimed to characterize potentially endophytic culturable bacteria from leaves of cultivated tomato and analyze their potential for growth promotion and biocontrol of diseases caused by Botrytis cinerea and Pseudomonas syringae. Bacteria were obtained from inner tissues of surface-disinfected tomato leaves of field-grown plants. Analysis of 16S rRNA gene sequences identified bacterial isolates related to Exiguobacterium aurantiacum (isolates BT3 and MT8), Exiguobacterium spp. (isolate GT4), Staphylococcus xylosus (isolate BT5), Pantoea eucalypti (isolate NT6), Bacillus methylotrophicus (isolate MT3), Pseudomonas veronii (isolates BT4 and NT2), Pseudomonas rhodesiae (isolate BT2) and Pseudomonas cichorii (isolate NT3). After seed inoculation, BT2, BT4, MT3, MT8, NT2 and NT6 were re-isolated from leaf extracts. NT2, BT2, MT3 and NT6 inhibited growth of Botrytis cinerea and Pseudomonas syringae pv. tomato in vitro, produced antimicrobial compounds and reduced leaf damage caused by B. cinerea. Some of these isolates also promoted growth of tomato plants, produced siderophores, the auxin indole-3-acetic and solubilized inorganic phosphate. Thus, bacterial communities of leaves from field-grown tomato plants were found to harbor potentially endophytic culturable beneficial bacteria capable of antagonizing pathogenic microorganisms and promoting plant growth, which could be used as biological control agents and biofertilizers/biostimulators for promotion of tomato plant growth. Copyright © 2015 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Characterization of bacterial isolates from rubber dump site and their use in biodegradation of isoprene in batch and continuous bioreactors.

PubMed

Srivastva, Navnita; Shukla, Awadhesh Kumar; Singh, Ram Sharan; Upadhyay, Siddh Nath; Dubey, Suresh Kumar

2015-01-01

Bacterial isolates from contaminated soil of a waste rubber dumping site were isolated and characterized using biochemical and molecular approaches. Isoprene degradation kinetics in batch mode (isoprene concentration: 100-1000 ppm) revealed the degradation efficiency of isolates as: Pseudomonas sp. (83%)>Alcaligenes sp. (70%)>Klebsiella sp. (68.5%). The most efficient isolate Pseudomonas sp. was finally inoculated in a specifically designed bioreactor system comprising a bioscrubber and a biofilter packed with polyurethane foam connected in series. The bioscrubber and biofilter units when operated in a series showed more than 90% removal efficiency up to the inlet loading rate (IL) of 371.1g/m(3)/h. Maximum elimination capacity (EC) of biofilter was found to be an order of magnitude greater than that for bioscrubber. Oxidative cleavage of the double bond of isoprene has been revealed through IR spectra of the leachate. Copyright © 2015 Elsevier Ltd. All rights reserved.

Studies on the factors modulating indole-3-acetic acid production in endophytic bacterial isolates from Piper nigrum and molecular analysis of ipdc gene.

PubMed

Jasim, B; Jimtha John, C; Shimil, V; Jyothis, M; Radhakrishnan, E K

2014-09-01

The study mainly aimed quantitative analysis of IAA produced by endophytic bacteria under various conditions including the presence of extract from Piper nigrum. Analysis of genetic basis of IAA production was also conducted by studying the presence and diversity of the ipdc gene among the selected isolates. Five endophytic bacteria isolated previously from P. nigrum were used for the study. The effect of temperature, pH, agitation, tryptophan concentration and plant extract on modulating IAA production of selected isolates was analysed by colorimetric method. Comparative and quantitative analysis of IAA production by colorimetric isolates under optimal culture condition was analysed by HPTLC method. Presence of ipdc gene and thereby biosynthetic basis of IAA production among the selected isolates were studied by PCR-based amplification and subsequent insilico analysis of sequence obtained. Among the selected bacterial isolates from P. nigrum, isolate PnB 8 (Klebsiella pneumoniae) was found to have the maximum yield of IAA under various conditions optimized and was confirmed by colorimetric, HPLC and HPTLC analysis. Very interestingly, the study showed stimulating effect of phytochemicals from P. nigrum on IAA production by endophytic bacteria isolated from same plant. This study is unique because of the selection of endophytes from same source for comparative and quantitative analysis of IAA production under various conditions. Study on stimulatory effect of phytochemicals on bacterial IAA production as explained in the study is a novel approach. Studies on molecular basis of IAA production which was confirmed by sequence analysis of ipdc gene make the study scientifically attractive. Even though microbial production of IAA is well known, current report on detailed optimization, effect of plant extract and molecular confirmation of IAA biosynthesis is comparatively novel in its approach. © 2014 The Society for Applied Microbiology.

Final Scientific Report: Bacterial Nanowires and Extracellular Electron Transfer to Heavy Metals and Radionuclides by Bacterial Isolates from DOE Field Research Centers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nealson, Kenneth

This proposal involved the study of bacteria capable of transferring electrons from the bacterial cells to electron acceptors located outside the cell. These could be either insoluble minerals that were transformed into soluble products upon the addition of electrons, or they could be soluble salts like uranium or chromium, that become insoluble upon the addition of electrons. This process is called extracellular electron transport or EET, and can be done directly by cellular contact, or via conductive appendages called bacterial nanowires. In this work we examined a number of different bacteria for their ability to perform EET, and also lookedmore » at their ability to produce conductive nanowires that can be used for EET at a distance away from the EET-capable cells. In the work, new bacteria were isolated, new abilities of EET were examined, and many new methods were developed, and carefully described in the literature. These studies set the stage for future work dealing with the bioremediation of toxic metals like uranium and chromium. They also point out that EET (and conductive nanowires) are far more common that had been appreciated, and may be involved with energy transfer not only in sediments, but in symbioses between different bacteria, and in symbiosis/pathogenesis between bacteria and higher organisms.« less

Predicted Bacterial Interactions Affect in Vivo Microbial Colonization Dynamics in Nematostella

PubMed Central

Domin, Hanna; Zurita-Gutiérrez, Yazmín H.; Scotti, Marco; Buttlar, Jann; Hentschel Humeida, Ute; Fraune, Sebastian

2018-01-01

The maintenance and resilience of host-associated microbiota during development is a fundamental process influencing the fitness of many organisms. Several host properties were identified as influencing factors on bacterial colonization, including the innate immune system, mucus composition, and diet. In contrast, the importance of bacteria–bacteria interactions on host colonization is less understood. Here, we use bacterial abundance data of the marine model organism Nematostella vectensis to reconstruct potential bacteria–bacteria interactions through co-occurrence networks. The analysis indicates that bacteria–bacteria interactions are dynamic during host colonization and change according to the host’s developmental stage. To assess the predictive power of inferred interactions, we tested bacterial isolates with predicted cooperative or competitive behavior for their ability to influence bacterial recolonization dynamics. Within 3 days of recolonization, all tested bacterial isolates affected bacterial community structure, while only competitive bacteria increased bacterial diversity. Only 1 week after recolonization, almost no differences in bacterial community structure could be observed between control and treatments. These results show that predicted competitive bacteria can influence community structure for a short period of time, verifying the in silico predictions. However, within 1 week, the effects of the bacterial isolates are neutralized, indicating a high degree of resilience of the bacterial community. PMID:29740401

Clonal structure in Ichthyobacterium seriolicida, the causative agent of bacterial haemolytic jaundice in yellowtail, Seriola quinqueradiata, inferred from molecular epidemiological analysis.

PubMed

Matsuyama, T; Fukuda, Y; Sakai, T; Tanimoto, N; Nakanishi, M; Nakamura, Y; Takano, T; Nakayasu, C

2017-08-01

Bacterial haemolytic jaundice caused by Ichthyobacterium seriolicida has been responsible for mortality in farmed yellowtail, Seriola quinqueradiata, in western Japan since the 1980s. In this study, polymorphic analysis of I. seriolicida was performed using three molecular methods: amplified fragment length polymorphism (AFLP) analysis, multilocus sequence typing (MLST) and multiple-locus variable-number tandem repeat analysis (MLVA). Twenty-eight isolates were analysed using AFLP, while 31 isolates were examined by MLST and MLVA. No polymorphisms were identified by AFLP analysis using EcoRI and MseI, or by MLST of internal fragments of eight housekeeping genes. However, MLVA revealed variation in repeat numbers of three elements, allowing separation of the isolates into 16 sequence types. The unweighted pair group method using arithmetic averages cluster analysis of the MLVA data identified four major clusters, and all isolates belonged to clonal complexes. It is likely that I. seriolicida populations share a common ancestor, which may be a recently introduced strain. © 2016 John Wiley & Sons Ltd.

Anticlostridial agent 8-hydroxyquinoline improves the isolation of faecal bifidobacteria on modified Wilkins-Chalgren agar with mupirocin.

PubMed

Novakova, J; Vlkova, E; Salmonova, H; Pechar, R; Rada, V; Kokoska, L

2016-04-01

The need for suitable selective cultivation media for the isolation of Bifidobacterium spp. continues to be a real concern in the field of intestinal microbiology. Isolation of bifidobacteria from human and animal faecal samples using selective agar plating may be problematic especially in samples with increased clostridial counts than bifidobacterial counts. Due to the absence of anticlostridial agents in existing selective media, clostridia can displace bifidobacteria resulting in incorrect estimation of their counts. Therefore, we supplemented the existing selective medium 'modified Wilkins Chalgren agar with mupirocin' (MWM) with 90 mg l(-1) of 8-hydroxyquinoline (8HQ), which was recently proved to act selectively against clostridia. The newly composed 'modified Wilkins-Chalgren agar with 8HQ' (MWMQ) was tested on pure bifidobacterial and clostridial strains, their mixtures, and using faecal samples of mammalian origin; its selectivity was evaluated by genus-specific identification of isolates. The results demonstrated that the presence of 8HQ in this agar eliminated the growth of nonbifidobacterial strains on MWMQ compared to that on MWM, whereas the recovery of bifidobacterial counts was at satisfactory levels. In conclusion, MWMQ could be recommended for bifidobacterial isolation from human and animal faeces especially when bifidobacteria are not numerically dominant and there are chances of clostridial contamination. Routine isolation of bifidobacteria from mammalian faeces does not use a reliable selective agar with an anticlostridial agent. Overgrowth of clostridia may result in incorrect estimation of bifidobacterial counts. Thus, in order to improve the selectivity of existing media for bifidobacterial isolation, we chose the modified Wilkins-Chalgren agar with mupirocin and supplemented it with 8-hydroxyquinoline (8HQ), a molecule that shows anticlostridial activity without affecting the growth of bifidobacteria. This newly composed medium showed

New target for inhibition of bacterial RNA polymerase: 'switch region'.

PubMed

Srivastava, Aashish; Talaue, Meliza; Liu, Shuang; Degen, David; Ebright, Richard Y; Sineva, Elena; Chakraborty, Anirban; Druzhinin, Sergey Y; Chatterjee, Sujoy; Mukhopadhyay, Jayanta; Ebright, Yon W; Zozula, Alex; Shen, Juan; Sengupta, Sonali; Niedfeldt, Rui Rong; Xin, Cai; Kaneko, Takushi; Irschik, Herbert; Jansen, Rolf; Donadio, Stefano; Connell, Nancy; Ebright, Richard H

2011-10-01

A new drug target - the 'switch region' - has been identified within bacterial RNA polymerase (RNAP), the enzyme that mediates bacterial RNA synthesis. The new target serves as the binding site for compounds that inhibit bacterial RNA synthesis and kill bacteria. Since the new target is present in most bacterial species, compounds that bind to the new target are active against a broad spectrum of bacterial species. Since the new target is different from targets of other antibacterial agents, compounds that bind to the new target are not cross-resistant with other antibacterial agents. Four antibiotics that function through the new target have been identified: myxopyronin, corallopyronin, ripostatin, and lipiarmycin. This review summarizes the switch region, switch-region inhibitors, and implications for antibacterial drug discovery. Copyright © 2011 Elsevier Ltd. All rights reserved.

Immersion Refractometry of Isolated Bacterial Cell Walls

PubMed Central

Marquis, Robert E.

1973-01-01

Immersion-refractometric and light-scattering measurements were adapted to determinations of average refractive indices and physical compactness of isolated bacterial cell walls. The structures were immersed in solutions containing various concentrations of polymer molecules that cannot penetrate into wall pores, and then an estimate was made of the polymer concentration or the refractive index of the polymer solution in which light scattering was reduced to zero. Because each wall preparation was heterogeneous, the refractive index of the medium for zero light scattering had to be estimated by extrapolation. Refractive indices for walls suspended in bovine serum albumin solutions ranged from 1.348 for walls of the rod form of Arthrobacter crystallopoietes to 1.382 for walls of the teichoic acid deficient, 52A5 strain of Staphylococcus aureus. These indices were used to calculate approximate values for solids content per milliliter, and the calculated values agreed closely with those estimated from a knowledge of dextran-impermeable volumes per gram, dry weight, of the walls. When large molecules such as dextrans or serum albumin were used for immersion refractometry, the refractive indices obtained were for entire walls, including both wall polymers and wall water. When smaller molecules that can penetrate wall pores to various extents were used with Micrococcus lysodeikticus walls, the average, apparent refractive index of the structures increased as the molecular size of probing molecules was decreased. It was possible to obtain an estimate of 1.45 to 1.46 for the refractive index of wall polymers, predominantly peptidoglycans in this case, by extrapolating the curve for refractive index versus molecular radius to a value of 0.2 nm, the approximate radius of a water molecule. This relatively low value for polymer refractive index was interpreted as evidence in favor of the amorphous, elastic model of peptidoglycan structure and against the crystalline, rigid

In vitro antagonistic effect of Lactobacillus on organisms associated with bacterial vaginosis.

PubMed

Strus, Magdalena; Malinowska, Magdalena; Heczko, Piotr B

2002-01-01

To assess antagonistic properties of Lactobacillus strains isolated from the vaginas of healthy women as compared to the most common bacterial agents related to vaginosis. Antagonistic activity of different Lactobacillus strains isolated from the vaginas of healthy women not treated for infections with an antibiotic for the previous three months was screened using an agar slab method. The activity was tested against test organisms associated with bacterial vaginosis and/or urinary tract infections: Staphylococcus aureus, Enterococcus faecalis, Streptococcus agalactiae, Escherichia coli, Gardnerella vaginalis, Peptostreptococcus anaerobius and Prevotella bivia. Many of the 146 Lactobacillus strains tested exerted apparent antagonistic activities against gram-positive aerobic cocci and gram-negative rods, such as S aureus and E coli, and a marked number of Lactobacillus strains inhibited facultative bacteria, such as Gardnerella vaginalis and the anaerobes P anaerobius and P bivia. Only a few lactobacilli were able to inhibit growth of E faecalis and S agalactiae. Indicator bacteria growth inhibition probably relies upon several different complementary mechanisms. The specific indicator bacteria species determines which mechanism predominates. Lactobacillus strains taken from normal vaginal flora demonstrated antagonistic activity against a variety of bacteria related to vaginal and urinary tract infections. The specific occurrence rates of active Lactobacillus strains are different, and this difference is dependent on the indicator bacteria species.

Susceptibility of bacterial isolates from community-acquired infections in sub-Saharan Africa and Asia to macrolide antibiotics.

PubMed

Lubell, Yoel; Turner, Paul; Ashley, Elizabeth A; White, Nicholas J

2011-10-01

To review the literature on the susceptibility of common community pathogens in sub-Saharan Africa and Asia to the macrolide antibiotics. Inclusion criteria required that isolates were collected since 2004 to ensure results were of contemporary relevance. The data were aggregated by region, age group and sterility of site of culture sample. A total of 51 studies were identified, which reported the macrolide antimicrobial susceptibilities of common bacterial pathogens isolated since 2004. In general, there was less macrolide resistance in African than in Asian isolates. Most African studies reported high levels of macrolide susceptibility in Streptococcus pneumoniae, whereas most Chinese studies reported high levels of resistance. There was very little information available for Gram-negative organisms. Susceptibility of the pneumococcus to macrolides in SSA remains high in many areas, and good activity of azithromycin has been shown against Salmonellae spp. in Asia. In urban areas where high antibiotic consumption is prevalent, there was evidence of increased resistance to macrolides. However, there is no information on susceptibility from large areas in both continents. © 2011 Blackwell Publishing Ltd.

Shared Bacterial and Viral Respiratory Agents in Bighorn Sheep (Ovis canadensis), Domestic Sheep (Ovis aries), and Goats (Capra hircus) in Montana

PubMed Central

Miller, David S.; Weiser, Glen C.; Aune, Keith; Roeder, Brent; Atkinson, Mark; Anderson, Neil; Roffe, Thomas J.; Keating, Kim A.; Chapman, Phillip L.; Kimberling, Cleon; Rhyan, Jack; Clarke, P. Ryan

2011-01-01

Transmission of infectious agents from livestock reservoirs has been hypothesized to cause respiratory disease outbreaks in bighorn sheep (Ovis canadensis), and land management policies intended to limit this transmission have proven controversial. This cross-sectional study compares the infectious agents present in multiple populations of bighorn sheep near to and distant from their interface with domestic sheep (O. aries) and domestic goat (Capra hircus) and provides critical baseline information needed for interpretations of cross-species transmission risks. Bighorn sheep and livestock shared exposure to Pasteurellaceae, viral, and endoparasite agents. In contrast, although the impact is uncertain, Mycoplasma sp. was isolated from livestock but not bighorn sheep. These results may be the result of historic cross-species transmission of agents that has resulted in a mosaic of endemic and exotic agents. Future work using longitudinal and multiple population comparisons is needed to rigorously establish the risk of outbreaks from cross-species transmission of infectious agents. PMID:22195293

Shared Bacterial and Viral Respiratory Agents in Bighorn Sheep (Ovis canadensis), Domestic Sheep (Ovis aries), and Goats (Capra hircus) in Montana.

PubMed

Miller, David S; Weiser, Glen C; Aune, Keith; Roeder, Brent; Atkinson, Mark; Anderson, Neil; Roffe, Thomas J; Keating, Kim A; Chapman, Phillip L; Kimberling, Cleon; Rhyan, Jack; Clarke, P Ryan

2011-01-01

Transmission of infectious agents from livestock reservoirs has been hypothesized to cause respiratory disease outbreaks in bighorn sheep (Ovis canadensis), and land management policies intended to limit this transmission have proven controversial. This cross-sectional study compares the infectious agents present in multiple populations of bighorn sheep near to and distant from their interface with domestic sheep (O. aries) and domestic goat (Capra hircus) and provides critical baseline information needed for interpretations of cross-species transmission risks. Bighorn sheep and livestock shared exposure to Pasteurellaceae, viral, and endoparasite agents. In contrast, although the impact is uncertain, Mycoplasma sp. was isolated from livestock but not bighorn sheep. These results may be the result of historic cross-species transmission of agents that has resulted in a mosaic of endemic and exotic agents. Future work using longitudinal and multiple population comparisons is needed to rigorously establish the risk of outbreaks from cross-species transmission of infectious agents.

Shared bacterial and viral respiratory agents in bighorn sheep (Ovis canadensis), domestic sheep (Ovis aries), and goats (Capra hircus) in Montana

USGS Publications Warehouse

Miller, David S.; Weiser, Glen C.; Aune, Keith; Roeder, Brent; Atkinson, Mark; Anderson, Neil; Roffe, Thomas J.; Keating, Kim A.; Chapman, Phillip L.; Kimberling, Cleon; Rhyan, Jack C.; Clarke, P. Ryan

2011-01-01

Transmission of infectious agents from livestock reservoirs has been hypothesized to cause respiratory disease outbreaks in bighorn sheep (Ovis canadensis), and land management policies intended to limit this transmission have proven controversial. This cross-sectional study compares the infectious agents present in multiple populations of bighorn sheep near to and distant from their interface with domestic sheep (O. aries) and domestic goat (Capra hircus) and provides critical baseline information needed for interpretations of cross-species transmission risks. Bighorn sheep and livestock shared exposure to Pasteurellaceae, viral, and endoparasite agents. In contrast, although the impact is uncertain, Mycoplasma sp. was isolated from livestock but not bighorn sheep. These results may be the result of historic cross-species transmission of agents that has resulted in a mosaic of endemic and exotic agents. Future work using longitudinal and multiple population comparisons is needed to rigorously establish the risk of outbreaks from cross-species transmission of infectious agents.

Isolation and characterization of pathogenic Vibrio alginolyticus from diseased cobia Rachycentron canadum.

PubMed

Liu, Ping-Chung; Lin, Ji-Yang; Hsiao, Pei-Tze; Lee, Kuo-Kau

2004-01-01

Outbreaks of serious mortality among cultured juvenile cobia Rachycentron canadum L. (weighing 8-10 g) characterized by lethargy, dark skin and ascites in the peritoneal cavity while some fish possessing damaged eyes occurred in July and August of 2001 in Taiwan. Fifteen motile bacterial strains were isolated from head kidney and/or the ascites on tryptic soy agar supplemented with 1% NaCl (TSA1) and/or thiosulphate citrate bile salt (TCBS) sucrose agar plates during the two outbreaks. All the isolates were characterized and identified as Vibrio alginolyticus on the basis of biochemical characteristics, and comparisons with those of the reference strain V. alginolyticus ATCC 17749. The strain C3c01 (a representative of the 15 similar field isolates), was virulent to the cobia with an LD50 value of 3.28 x 10(4) colony forming units/g fish body weight. All the moribund/dead fish exhibited lethargy, dark skin and ascites in the peritoneal cavity as that observed in natural outbreaks. The same bacteria could be reisolated from kidney and the ascites of fish after bacterial challenge using TSA1 and TCBS plates. The results reveal that V. alginolyticus is an infectious agent of vibriosis in the cobia.

Bacterial vaginosis-associated microflora isolated from the female genital tract activates HIV-1 expression.

PubMed

Al-Harthi, L; Roebuck, K A; Olinger, G G; Landay, A; Sha, B E; Hashemi, F B; Spear, G T

1999-07-01

Alteration of cervicovaginal microbial flora can lead to vaginosis, which is associated with an increased risk of HIV-1 transmission. We recently characterized a soluble HIV-inducing factor (HIF) from the cervicovaginal lavage (CVL) samples of women. The goals of this study were to determine the effect of cervicovaginal microflora on HIV-1 expression and to elucidate the relationship between HIF activity and microflora. Physiologically relevant microorganisms, Mycoplasma, diphtheroid-like bacteria, Gardnerella vaginalis, Streptococcus agalactiae, and Streptococcus constellatus, cultured from the CVL of a representative woman with a clinical condition of bacterial vaginosis and possessing HIF activity, induced HIV-1 expression. The magnitude of virus induction varied widely with the greatest stimulation induced by diphtheroid-like bacteria and Mycoplasma. The transcriptional induction by Mycoplasma was mediated by activation of the KB enhancer, an activation mechanism shared with HIF. Also as with HIF, Mycoplasma induced AP-1 dependent transcription. Polymerase chain reaction (PCR)-based speciation showed that the isolate was M. hominis. Our data indicate that bacterial vaginosis-associated microflora can enhance HIV-1 transcription and replication and identify M. hominis as a potential source for HIF activity. The virus-enhancing activities associated with the microflora and HIF may increase genital tract viral load, potentially contributing to HIV transmission.

Diversity of Hindgut Bacterial Population in Subterranean Termite, Reticulitermes flavipes

Treesearch

Olanrewaju Raji; Dragica Jeremic-Nikolic; Juliet D. Tang

2017-01-01

The termite hindgut contains a bacterial community that symbiotically aids in digestion of cellulosic materials. For this paper, a species survey of bacterial hindgut symbionts in termites collected from Saucier, Mississippi was examined. Two methods were tested for optimal genetic material isolation. Genomic DNA was isolated from the hindgut luminal contents of five...

Multidrug Efflux Pumps from Enterobacteriaceae, Vibrio cholerae and Staphylococcus aureus Bacterial Food Pathogens

PubMed Central

Andersen, Jody L.; He, Gui-Xin; Kakarla, Prathusha; KC, Ranjana; Kumar, Sanath; Lakra, Wazir Singh; Mukherjee, Mun Mun; Ranaweera, Indrika; Shrestha, Ugina; Tran, Thuy; Varela, Manuel F.

2015-01-01

Foodborne illnesses caused by bacterial microorganisms are common worldwide and constitute a serious public health concern. In particular, microorganisms belonging to the Enterobacteriaceae and Vibrionaceae families of Gram-negative bacteria, and to the Staphylococcus genus of Gram-positive bacteria are important causative agents of food poisoning and infection in the gastrointestinal tract of humans. Recently, variants of these bacteria have developed resistance to medically important chemotherapeutic agents. Multidrug resistant Escherichia coli, Salmonella enterica, Vibrio cholerae, Enterobacter spp., and Staphylococcus aureus are becoming increasingly recalcitrant to clinical treatment in human patients. Of the various bacterial resistance mechanisms against antimicrobial agents, multidrug efflux pumps comprise a major cause of multiple drug resistance. These multidrug efflux pump systems reside in the biological membrane of the bacteria and actively extrude antimicrobial agents from bacterial cells. This review article summarizes the evolution of these bacterial drug efflux pump systems from a molecular biological standpoint and provides a framework for future work aimed at reducing the conditions that foster dissemination of these multidrug resistant causative agents through human populations. PMID:25635914

Multidrug efflux pumps from Enterobacteriaceae, Vibrio cholerae and Staphylococcus aureus bacterial food pathogens.

PubMed

Andersen, Jody L; He, Gui-Xin; Kakarla, Prathusha; K C, Ranjana; Kumar, Sanath; Lakra, Wazir Singh; Mukherjee, Mun Mun; Ranaweera, Indrika; Shrestha, Ugina; Tran, Thuy; Varela, Manuel F

2015-01-28

Foodborne illnesses caused by bacterial microorganisms are common worldwide and constitute a serious public health concern. In particular, microorganisms belonging to the Enterobacteriaceae and Vibrionaceae families of Gram-negative bacteria, and to the Staphylococcus genus of Gram-positive bacteria are important causative agents of food poisoning and infection in the gastrointestinal tract of humans. Recently, variants of these bacteria have developed resistance to medically important chemotherapeutic agents. Multidrug resistant Escherichia coli, Salmonella enterica, Vibrio cholerae, Enterobacter spp., and Staphylococcus aureus are becoming increasingly recalcitrant to clinical treatment in human patients. Of the various bacterial resistance mechanisms against antimicrobial agents, multidrug efflux pumps comprise a major cause of multiple drug resistance. These multidrug efflux pump systems reside in the biological membrane of the bacteria and actively extrude antimicrobial agents from bacterial cells. This review article summarizes the evolution of these bacterial drug efflux pump systems from a molecular biological standpoint and provides a framework for future work aimed at reducing the conditions that foster dissemination of these multidrug resistant causative agents through human populations.

Antimicrobial susceptibility of Brachyspira hyodysenteriae isolated from 21 Polish farms.

PubMed

Zmudzki, J; Szczotka, A; Nowak, A; Strzelecka, H; Grzesiak, A; Pejsak, Z

2012-01-01

Swine dysentery (SD) is a common disease among pigs worldwide, which contributes to major production losses. Antimicrobial susceptibility testing of B. hyodysenteriae, the etiological agent of SD, is mainly performed by the agar dilution method. This method has certain limitations due to difficulties in interpretation of results. The aim of this study was the analysis of antimicrobial susceptibility of Brachyspira hyodysenteriae (B. hyodysenteriae) Polish field isolates by broth microdilution procedure. The study was performed on 21 isolates of B. hyodysenteriae, collected between January 2006 to December 2010 from cases of swine dysentery. VetMIC Brachyspira panels with antimicrobial agents (tiamulin, valnemulin, doxycycline, lincomycin, tylosin and ampicillin) were used for susceptibility testing of B. hyodysenteriae. The minimal inhibitory concentration (MIC) was determined by the broth dilution procedure. The lowest antimicrobial activity was demonstrated for tylosin and lincomycin, with inhibition of bacterial growth using concentrations > 128 microg/ml and 32 microg/ml, respectively. In the case of doxycycline, the MIC values were < or = 2.0 microg/ml. No decreased susceptibility to tiamulin was found among the Polish isolates and MIC values for this antibiotic did not exceed 1.0 microg/ml. The results of the present study confirmed that Polish B. hyodysenteriae isolates were susceptible to the main antibiotics (tiamulin and valnemulin) used in treatment of swine dysentery. Further studies are necessary to evaluate a possible slow decrease in susceptibility to tiamulin and valnemulin of B. hyodysenteriae strains in Poland.

Action of cholecystokinin and cholinergic agents on calcium transport in isolated pancreatic acinar cells.

PubMed Central

Gardner, J D; Conlon, T P; Kleveman, H L; Adams, T D; Ondetti, M A

1975-01-01

COOH-terminal octapeptide of cholecystokinin (CCK-octapeptide) and the cholinergic agent carbamylcholine each produced a fourfold stimulation of calcium outflux in guinea pig isolated pancreatic acinar cells. Neither agent altered calcium influx. Stimulation of calcium outflux was rapid and specific, was abolished by reducing the incubation temperature to 4 degrees C, and was a saturable function of the secretagogue concentration. The concentrations of CCK-octapeptide and carbamylcholine that produced half-maximal stimulation of calcium outflux were 3.1 x 10(-10) M and 4.9 x 10(-5) M, respectively. The cholinergic antagonist antropine competitively inhibited carbamylcholine stimulation of calcium outflux but did not alter stimulation produced by CCK-octapeptide. Stimulation of calcium outflux by maximal concentrations of carbamycholine plus CCK-octapeptide was the same as that produced by a maximal concentration of either agent alone.Calcium outflux became refractory to stimulation by secretagogues, and incubation with either CCK-ostapeptide or carbamylcholine produced a refractoriness to both agents. The relative potencies with CCK and its related fragments stimulated calcium outflux were CCK-octapeptide greater than heptapeptide greater than CCK greater than hexapeptide = gastrin. Secretin, glucagon, and vasoactive intestinal peptide, at concentrations as high as 10(-5) M, failed to alter calcium outflux and did not affect stimulation by CCK-octapeptide or by carbamycholine. Images PMID:1150877

In Vitro Activity of Pexiganan and 10 Comparator Antimicrobials against 234 Isolates, Including 93 Pasteurella Species and 50 Anaerobic Bacterial Isolates Recovered from Animal Bite Wounds

PubMed Central

Citron, Diane M.; Tyrrell, Kerin L.; Leoncio, Eliza S.

2017-01-01

ABSTRACT Animal bite wounds affect more than 5 million Americans annually, resulting in 300,000 emergency department visits, 10,000 hospitalizations, and an untold number of physician office visits. Various forms of topical therapy are empirically self-employed by many patients prior to seeking medical attention. Pexiganan, a 22-amino-acid synthetic cationic analogue of the peptide magainin II, acts by selectively damaging bacterial cell membranes. We determined the MICs for pexiganan and other antimicrobial agents often used for treatment of bite wounds. Most isolates were from U.S. patients, and ∼10% were from European and Canadian patients. The comparator antimicrobials studied were penicillin, amoxicillin-clavulanate, piperacillin-tazobactam, meropenem, clindamycin, doxycycline, moxifloxacin, ceftriaxone, linezolid, and metronidazole. The MIC90s of pexiganan were 32 μg/ml (against Pasteurella multocida subsp. multocida), 16 μg/ml (P. multocida subsp. septica, Pasteurella canis, and Pasteurella dagmatis), 8 μg/ml (Pasteurella stomatis), 8 μg/ml (Eikenella corrodens), 2 μg/ml (Neisseria weaveri, Neisseria zoodegmatis, and Moraxella canis-Moraxella lacunata group), 16 μg/ml (Bergeyella zoohelcum), 64 μg/ml (Bacteroides pyogenes), 4 μg/ml (Fusobacterium russii), 32 μg/ml (Fusobacterium canifelinum), and 64 μg/ml (Prevotella heparinolytica). The concentration of pexiganan in the cream used was 8,000 μg/ml, more than 60 to 100 times the highest MIC obtained. Pexiganan exhibited a broad range of antimicrobial activity, showing potential for treating animal bite infections. A clinical trial seems warranted. PMID:28373186

Bacillus methylotrophicus Strain NKG-1, Isolated from Changbai Mountain, China, Has Potential Applications as a Biofertilizer or Biocontrol Agent

PubMed Central

Ge, Beibei; Liu, Binghua; Nwet, Thinn Thinn; Zhao, Wenjun; Shi, Liming; Zhang, Kecheng

2016-01-01

Chemical pesticides are widely used in agriculture, which endangers both environmental health and food safety. Biocontrol is an environmentally-friendly and cost-effective green technique in environmental protection and agricultural production; it generally uses selected bioresources, including beneficial microorganisms. We isolated a novel bacterial strain (NKG-1) from the rare dormant volcanic soils of Changbai Mountain in China’s Jilin Province. The strain was identified as Bacillus methylotrophicus using morphological, biochemical, physiological, and phylogenetic 16S rDNA sequencing data. This strain was able to suppress mycelial growth and conidial germination of numerous plant pathogenic fungi on solid media. A greenhouse experiment showed that application of NKG-1 fermentation broth prior to inoculation of Botrytis cinerea, the cause of gray tomato mold, inhibited growth of the mold by 60%. Furthermore, application of a 100× dilution of NKG-1 fermentation broth to tomato seedlings yielded a significant increase in seedling fresh weight (27.4%), seedling length (12.5%), and root length (57.7%) compared to the control. When the same dosage was applied in the field, we observed increases in tomato plant height (14.7%), stem diameter (12.7%), crown width (16.3%), and maximum fruit diameter (11.5%). These results suggest that NKG-1 has potential commercial application as a biofertilizer or biocontrol agent. PMID:27832162

Modeling physiological resistance in bacterial biofilms.

PubMed

Cogan, N G; Cortez, Ricardo; Fauci, Lisa

2005-07-01

A mathematical model of the action of antimicrobial agents on bacterial biofilms is presented. The model includes the fluid dynamics in and around the biofilm, advective and diffusive transport of two chemical constituents and the mechanism of physiological resistance. Although the mathematical model applies in three dimensions, we present two-dimensional simulations for arbitrary biofilm domains and various dosing strategies. The model allows the prediction of the spatial evolution of bacterial population and chemical constituents as well as different dosing strategies based on the fluid motion. We find that the interaction between the nutrient and the antimicrobial agent can reproduce survival curves which are comparable to other model predictions as well as experimental results. The model predicts that exposing the biofilm to low concentration doses of antimicrobial agent for longer time is more effective than short time dosing with high antimicrobial agent concentration. The effects of flow reversal and the roughness of the fluid/biofilm are also investigated. We find that reversing the flow increases the effectiveness of dosing. In addition, we show that overall survival decreases with increasing surface roughness.

Helminthic transmission and isolation of Ehrlichia risticii, the causative agent of Potomac horse fever, by using trematode stages from freshwater stream snails.

PubMed

Pusterla, N; Madigan, J E; Chae, J S; DeRock, E; Johnson, E; Pusterla, J B

2000-03-01

We report successful helminthic transmission of Ehrlichia risticii, the causative agent of Potomac horse fever, using trematode stages collected from Juga yrekaensis snails. The ehrlichial agent was isolated from the blood of experimentally infected horses by culture in murine monocytic cells and identified as E. risticii ultrastructurally and by characterization of three different genes.

In-vitro activity of several antimicrobial agents against methicillin-resistant Staphylococcus aureus (MRSA) isolates expressing aminoglycoside-modifying enzymes: potency of plazomicin alone and in combination with other agents.

PubMed

López Díaz, María Carmen; Ríos, Esther; Rodríguez-Avial, Iciar; Simaluiza, Rosa Janneth; Picazo, Juan José; Culebras, Esther

2017-08-01

This study investigated the in-vitro activity of clinically relevant aminoglycosides and new antimicrobial agents-plazomicin, ceftobiprole and dalbavancin-against 55 methicillin-resistant Staphylococcus aureus (MRSA) isolates producing aminoglycoside-modifying enzymes (AMEs). The checkerboard method was used to assess synergism between plazomicin and four antibiotics (fosfomycin, ceftobiprole, cefoxitin and meropenem), and time-kill assays were performed for the most active combinations. Among the aminoglycosides tested, plazomicin was the most active agent against MRSA, with >90% of isolates being inhibited at a minimum inhibitory concentration (MIC) of ≤1 mg/L. MIC 50 and MIC 90 values for ceftobiprole and dalbavancin were 2 and 4 mg/L, and 0.125 and 0.125 mg/L, respectively. The most prevalent AME gene was aac(6')Ie-aph(2″)Ia (87.3%), followed by ant(4')Ia (52.7%) and aph(3')IIIa (52.7%). Plazomicin activity was not affected by the type or number of enzymes detected. In checkerboard and time-kill assays, indifference was the most common result achieved for the antibiotic combinations. Notably, no antagonism was observed with any combination tested. Overall, plazomicin in combination with meropenem had the highest synergistic effect, demonstrating synergy against seven isolates in the checkerboard assay and three isolates in time-kill curves. In conclusion, plazomicin showed potent activity against aminoglycoside-resistant MRSA isolates, regardless of the number and type of AMEs present. These findings indicate the potential utility of plazomicin in combination with meropenem for the treatment of MRSA infections. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis.

PubMed

Brouwer, Matthijs C; Tunkel, Allan R; van de Beek, Diederik

2010-07-01

The epidemiology of bacterial meningitis has changed as a result of the widespread use of conjugate vaccines and preventive antimicrobial treatment of pregnant women. Given the significant morbidity and mortality associated with bacterial meningitis, accurate information is necessary regarding the important etiological agents and populations at risk to ascertain public health measures and ensure appropriate management. In this review, we describe the changing epidemiology of bacterial meningitis in the United States and throughout the world by reviewing the global changes in etiological agents followed by specific microorganism data on the impact of the development and widespread use of conjugate vaccines. We provide recommendations for empirical antimicrobial and adjunctive treatments for clinical subgroups and review available laboratory methods in making the etiological diagnosis of bacterial meningitis. Finally, we summarize risk factors, clinical features, and microbiological diagnostics for the specific bacteria causing this disease.

Comparison of Lactobacillus crispatus isolates from Lactobacillus-dominated vaginal microbiomes with isolates from microbiomes containing bacterial vaginosis-associated bacteria

PubMed Central

Abdelmaksoud, Abdallah A.; Koparde, Vishal N.; Sheth, Nihar U.; Serrano, Myrna G.; Glascock, Abigail L.; Fettweis, Jennifer M.; Strauss, Jerome F.; Buck, Gregory A.

2016-01-01

Vaginal lactobacilli can inhibit colonization by and growth of other bacteria, thereby preventing development of bacterial vaginosis (BV). Amongst the lactobacilli, Lactobacillus crispatus appears to be particularly effective at inhibiting growth of BV-associated bacteria. Nonetheless, some women who are colonized with this species can still develop clinical BV. Therefore, we sought to determine whether strains of L. crispatus that colonize women with lactobacilli-dominated vaginal microbiomes are distinct from strains that colonize women who develop BV. The genomes of L. crispatus isolates from four women with lactobacilli-dominated vaginal microbiomes ( < 1 % 16S rRNA reads above threshold from genera other than Lactobacillus) and four women with microbiomes containing BV-associated bacteria (>12 % 16S rRNA reads from bacterial taxa associated with BV) were sequenced and compared. Lactic acid production by the different strains was quantified. Phage induction in the strains was also analysed. There was considerable genetic diversity between strains, and several genes were exclusive to either the strains from Lactobacillus-dominated microbiomes or those containing BV-associated bacteria. Overall, strains from microbiomes dominated by lactobacilli did not differ from strains from microbiomes containing BV-associated bacteria with respect to lactic acid production. All of the strains contained multiple phage, but there was no clear distinction between the presence or absence of BV-associated bacteria with respect to phage-induced lysis. Genes found to be exclusive to the Lactobacillus-dominated versus BV-associated bacteria-containing microbiomes could play a role in the maintenance of vaginal health and the development of BV, respectively. PMID:26747455

Comparison of Lactobacillus crispatus isolates from Lactobacillus-dominated vaginal microbiomes with isolates from microbiomes containing bacterial vaginosis-associated bacteria.

PubMed

Abdelmaksoud, Abdallah A; Koparde, Vishal N; Sheth, Nihar U; Serrano, Myrna G; Glascock, Abigail L; Fettweis, Jennifer M; Strauss, Jerome F; Buck, Gregory A; Jefferson, Kimberly K

2016-03-01

Vaginal lactobacilli can inhibit colonization by and growth of other bacteria, thereby preventing development of bacterial vaginosis (BV). Amongst the lactobacilli, Lactobacillus crispatus appears to be particularly effective at inhibiting growth of BV-associated bacteria. Nonetheless, some women who are colonized with this species can still develop clinical BV. Therefore, we sought to determine whether strains of L. crispatus that colonize women with lactobacilli-dominated vaginal microbiomes are distinct from strains that colonize women who develop BV. The genomes of L. crispatus isolates from four women with lactobacilli-dominated vaginal microbiomes ( <1% 16S rRNA reads above threshold from genera other than Lactobacillus) and four women with microbiomes containing BV-associated bacteria (>12% 16S rRNA reads from bacterial taxa associated with BV) were sequenced and compared. Lactic acid production by the different strains was quantified. Phage induction in the strains was also analysed. There was considerable genetic diversity between strains, and several genes were exclusive to either the strains from Lactobacillus-dominated microbiomes or those containing BV-associated bacteria. Overall, strains from microbiomes dominated by lactobacilli did not differ from strains from microbiomes containing BV-associated bacteria with respect to lactic acid production. All of the strains contained multiple phage, but there was no clear distinction between the presence or absence of BV-associated bacteria with respect to phage-induced lysis. Genes found to be exclusive to the Lactobacillus-dominated versus BV-associated bacteria-containing microbiomes could play a role in the maintenance of vaginal health and the development of BV, respectively.

First isolation of Haemophilus parasuis and other NAD-dependent Pasteurellaceae of swine from European wild boars.

PubMed

Olvera, A; Cerdà-Cuéllar, M; Mentaberre, G; Casas-Diaz, E; Lavin, S; Marco, I; Aragon, V

2007-11-15

Haemophilus parasuis is a colonizer of the upper respiratory tract of pigs and the etiological agent of Glässer's disease, which is characterized by a fibrinous polyserositis, meningitis and arthritis. Glässer's disease has never been reported in wild boar (Sus scrofa), although antibodies against H. parasuis have been detected. The goal of this study was to confirm the presence of this bacterium in wild boar by bacterial isolation and to compare the strains to H. parasuis from domesticated pigs. Therefore, nasal swabs from 42 hunted wild boars were processed for bacterial isolation and subsequent H. parasuis identification by specific PCR, biochemical tests and 16S rRNA gene sequencing. Two different strains of H. parasuis from two wild boars were isolated. These strains belonged to serotype 2 and were included by 16S rRNA gene sequencing and MLST analysis in a cluster with other H. parasuis strains of nasal origin from domestic pigs. During this study, Actinobacillus minor and Actinobacillus indolicus, which are NAD-dependent Pasteurellaceae closely related to H. parasuis, were also isolated. Our results indicate similarities in the respiratory microbiota of wild boars and domestic pigs, and although H. parasuis was isolated from wild boars, more studies are needed to determine if this could be a source of H. parasuis infection for domestic pigs.

Isolation and identification of biocontrol agent Streptomyces rimosus M527 against Fusarium oxysporum f. sp. cucumerinum.

PubMed

Lu, Dandan; Ma, Zheng; Xu, Xianhao; Yu, Xiaoping

2016-08-01

Actinomycetes have received considerable attention as biocontrol agents against fungal plant pathogens and as plant growth promoters. In this study, a total of 320 actinomycetes were isolated from various habitats in China. Among which, 77 strains have been identified as antagonistic activities against Fusarium oxysporum f. sp. cucumerinum which usually caused fusarium wilt of cucumber. Of these, isolate actinomycete M527 not only displayed broad-spectrum antifungal activity but also showed the strongest antagonistic activity against the spore germination of F. oxysporum f. sp. cucumerinum. In pot experiments, the results indicated that isolate M527 could promote the shoot growth and prevent the development of the disease on cucumber caused by F. oxysporum f. sp. cucumerinum. The control efficacy against seedling fusarium wilt of cucumber after M527 fermentation broth root-irrigation was up to 72.1% as compared to control. Based on 16S rDNA sequence analysis, the isolate M527 was identified as Streptomyces rimosus. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of two real-time multiplex PCR assays for the detection and quantification of eight key bacterial pathogens in lower respiratory tract infections

PubMed Central

Gadsby, N.J.; McHugh, M.P.; Russell, C.D.; Mark, H.; Conway Morris, A.; Laurenson, I.F.; Hill, A.T.; Templeton, K.E.

2015-01-01

The frequent lack of a positive and timely microbiological diagnosis in patients with lower respiratory tract infection (LRTI) is an important obstacle to antimicrobial stewardship. Patients are typically prescribed broad-spectrum empirical antibiotics while microbiology results are awaited, but, because these are often slow, negative, or inconclusive, de-escalation to narrow-spectrum agents rarely occurs in clinical practice. The aim of this study was to develop and evaluate two multiplex real-time PCR assays for the sensitive detection and accurate quantification of Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus, Moraxella catarrhalis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. We found that all eight bacterial targets could be reliably quantified from sputum specimens down to a concentration of 100 CFUs/reaction (8333 CFUs/mL). Furthermore, all 249 positive control isolates were correctly detected with our assay, demonstrating effectiveness on both reference strains and local clinical isolates. The specificity was 98% on a panel of nearly 100 negative control isolates. Bacterial load was quantified accurately when three bacterial targets were present in mixtures of varying concentrations, mimicking likely clinical scenarios in LRTI. Concordance with culture was 100% for culture-positive sputum specimens, and 90% for bronchoalveolar lavage fluid specimens, and additional culture-negative bacterial infections were detected and quantified. In conclusion, a quantitative molecular test for eight key bacterial causes of LRTI has the potential to provide a more sensitive decision-making tool, closer to the time-point of patient admission than current standard methods. This should facilitate de-escalation from broad-spectrum to narrow-spectrum antibiotics, substantially improving patient management and supporting efforts to curtail inappropriate antibiotic use. PMID:25980353

Petroleum residues degradation in laboratory-scale by rhizosphere bacteria isolated from the mangrove ecosystem

NASA Astrophysics Data System (ADS)

Rinanti, A.; Nainggolan, I. J.

2018-01-01

This research is about petroleum bioremediation experiment to obtain bacterial isolate from mangrove ecosystem which potentially degrade petroleum. It was conducted in an Erlenmeyer batch system filled with growth medium of Stone Mineral Salt Solution (SMSS) plus petroleum residue, placed in an incubator shaker with a rotation speed of 120 rpm, temperature 3000C, for 14 research days. Indigenous bacteria that have been isolated and identified from the roots of mangrove plants are Ochrobactrum anthropi and Bacillus sp., Ralstonia pickettii and Bacillus circulans. Those bacteriain both monoculture and consortium form (mixed culture) are incorporated into erlenmeyer as remediator agents. All bacteria can utilize hydrocarbon compounds, but Ralstonia pickettii and Bacillus circulans reached exponential phase faster with more cell count than other bacteria. Compared to single cultures, petroleum degradation by a bacterial consortium provides a higher TPH reduction efficiency, i.e. at 5%, 10%, and 15% of initial TPH of 94.4%, 72%, and 80.3%, respectively. This study proved that all bacteria could optimize hydrocarbon compounds up to 15% TPH load.

Helminthic Transmission and Isolation of Ehrlichia risticii, the Causative Agent of Potomac Horse Fever, by Using Trematode Stages from Freshwater Stream Snails

PubMed Central

Pusterla, Nicola; Madigan, John E.; Chae, Joon-Seok; DeRock, Elfriede; Johnson, Eileen; Pusterla, Jeannine Berger

2000-01-01

We report successful helminthic transmission of Ehrlichia risticii, the causative agent of Potomac horse fever, using trematode stages collected from Juga yrekaensis snails. The ehrlichial agent was isolated from the blood of experimentally infected horses by culture in murine monocytic cells and identified as E. risticii ultrastructurally and by characterization of three different genes. PMID:10699046

Bioremediation potential of a highly mercury resistant bacterial strain Sphingobium SA2 isolated from contaminated soil.

PubMed

Mahbub, Khandaker Rayhan; Krishnan, Kannan; Megharaj, Mallavarapu; Naidu, Ravi

2016-02-01

A mercury resistant bacterial strain, SA2, was isolated from soil contaminated with mercury. The 16S rRNA gene sequence of this isolate showed 99% sequence similarity to the genera Sphingobium and Sphingomonas of α-proteobacteria group. However, the isolate formed a distinct phyletic line with the genus Sphingobium suggesting the strain belongs to Sphingobium sp. Toxicity studies indicated resistance to high levels of mercury with estimated EC50 values 4.5 mg L(-1) and 44.15 mg L(-1) and MIC values 5.1 mg L(-1) and 48.48 mg L(-1) in minimal and rich media, respectively. The strain SA2 was able to volatilize mercury by producing mercuric reductase enzyme which makes it potential candidate for remediating mercury. ICP-QQQ-MS analysis of Hg supplemented culture solutions confirmed that almost 79% mercury in the culture suspension was volatilized in 6 h. A very small amount of mercury was observed to accumulate in cell pellets which was also evident according to ESEM-EDX analysis. The mercuric reductase gene merA was amplified and sequenced. The deduced amino acid sequence demonstrated sequence homology with α-proteobacteria and Ascomycota group. Copyright © 2015 Elsevier Ltd. All rights reserved.

Selected Essential Oils as Antifungal Agents Against Antibiotic-Resistant Candida spp.: In Vitro Study on Clinical and Food-Borne Isolates.

PubMed

Rajkowska, Katarzyna; Kunicka-Styczyńska, Alina; Maroszyńska, Marta

2017-01-01

Candida spp. cause significant health problems, inducing various types of superficial and deep-seated mycoses in humans. As a result of the increasing antibiotic resistance among pathogenic yeasts, the interest in alternative agents of antifungal activity is growing. This study evaluated the antimicrobial activity of selected essential oils (EOs) against Candida clinical and food-borne strains, including antibiotic-resistant isolates, in relation to yeast cell surface hydrophobicity (CSH). Candida strains showed different range of susceptibility to tea tree, thyme, peppermint, and clove oils, and peppermint oil demonstrated the lowest anticandidal activity with minimal inhibitory concentrations (MICs) of 0.03-8.0% v/v. MIC values for thyme and clove oils ranged from 0.03% to 0.25% v/v, and for tea tree oil-from 0.12% to 2.0% v/v. The exception was Candida tropicalis food-borne strain, the growth of which was inhibited after application of EOs at concentration of 8% v/v. Due to diverse yeast susceptibility to EOs, isolates were divided into five clusters in a principal component analysis model, each containing both clinical and food-borne strains. Hydrophobic properties of yeast were also diversified, and 37% of clinical and 50% of food-borne strains exhibited high hydrophobicity. The study indicates high homology of clinical and food-borne Candida isolates in relation to their susceptibility to anticandidal agents and hydrophobic properties. The susceptibility of yeasts to EOs could be partially related to their CSH. High antifungal activity of examined EOs, also against antibiotic-resistant isolates, indicates their usefulness as agents preventing the development of Candida strains of different origin.

Tetrahedral DNA Nanoparticle Vector for Intracellular Delivery of Targeted Peptide Nucleic Acid Antisense Agents to Restore Antibiotic Sensitivity in Cefotaxime-Resistant Escherichia coli.

PubMed

Readman, John Benedict; Dickson, George; Coldham, Nick G

2017-06-01

The bacterial cell wall presents a barrier to the uptake of unmodified synthetic antisense oligonucleotides, such as peptide nucleic acids, and so is one of the greatest obstacles to the development of their use as therapeutic anti-bacterial agents. Cell-penetrating peptides have been covalently attached to antisense agents, to facilitate penetration of the bacterial cell wall and deliver their cargo into the cytoplasm. Although they are an effective vector for antisense oligonucleotides, they are not specific for bacterial cells and can exhibit growth inhibitory properties at higher doses. Using a bacterial cell growth assay in the presence of cefotaxime (CTX 16 mg/L), we have developed and evaluated a self-assembling non-toxic DNA tetrahedron nanoparticle vector incorporating a targeted anti-bla CTX-M-group 1 antisense peptide nucleic acid (PNA4) in its structure for penetration of the bacterial cell wall. A dose-dependent CTX potentiating effect was observed when PNA4 (0-40 μM) was incorporated into the structure of a DNA tetrahedron vector. The minimum inhibitory concentration (to CTX) of an Escherichia coli field isolate harboring a plasmid carrying bla CTX-M-3 was reduced from 35 to 16 mg/L in the presence of PNA4 carried by the DNA tetrahedron vector (40 μM), contrasting with no reduction in MIC in the presence of PNA4 alone. No growth inhibitory effects of the DNA tetrahedron vector alone were observed.

Bioflocculant production and biosorption of zinc and lead by a novel bacterial species, Achromobacter sp. TERI-IASST N, isolated from oil refinery waste.

PubMed

Subudhi, Sanjukta; Batta, Neha; Pathak, Mihirjyoti; Bisht, Varsha; Devi, Arundhuti; Lal, Banwari; Al khulifah, Bader

2014-10-01

A bioflocculant-producing bacterial isolate designated as 'TERI-IASST N' was isolated from activated sludge samples collected from an oil refinery. This isolate demonstrated maximum bioflocculation activity (74%) from glucose among 15 different bioflocculant-producing bacterial strains isolated from the sludge samples and identified as Achromobacter sp. based on 16S rRNA gene sequence. Optimization of pH and supplementation of urea as nitrogen source in the production medium enhanced the flocculation activity of strain TERI-IASST N to 84% (at pH 6). This strain revealed maximum flocculation activity (90%) from sucrose compared to the flocculation activity observed from other carbon sources as investigated (glucose, lactose, fructose, maltose and starch). Ca(2+) served as the suitable divalent cation for maximum bioflocculation activity of TERI-IASST strain N. Maximum flocculation activity was observed at optimum C/N ratio of 1. Flocculation activity of this strain decreased to 75% in the presence of heavy metals; Zn, Pb, Ni, Cu and Cd. In addition strain N revealed considerable biosorption of Zn (430mgL(-1)) and Pb (30mgL(-1)). Bioflocculant yield of strain N was 10.5gL(-1). Fourier transform infrared spectrum indicated the presence of carboxyl, hydroxyl, and amino groups, typical of glycoprotein. Spectroscopic analysis of bioflocculant by nuclear magnetic resonance revealed that it is a glycoprotein, consisting of 57% total sugar and 13% protein. Copyright © 2014 Elsevier Ltd. All rights reserved.

Potential and use of bacterial small RNAs to combat drug resistance: a systematic review

PubMed Central

Liu, Xiaodong; Zhang, Lin; Wong, Sunny Hei; Chan, Matthew TV; Wu, William KK

2017-01-01

Background Over the decades, new antibacterial agents have been developed in an attempt to combat drug resistance, but they remain unsuccessful. Recently, a novel class of bacterial gene expression regulators, bacterial small RNAs (sRNAs), has received increasing attention toward their involvement in antibiotic resistance. This systematic review aimed to discuss the potential of these small molecules as antibacterial drug targets. Methods Two investigators performed a comprehensive search of MEDLINE, EmBase, and ISI Web of Knowledge from inception to October 2016, without restriction on language. We included all in vitro and in vivo studies investigating the role of bacterial sRNA in antibiotic resistance. Risk of bias of the included studies was assessed by a modified guideline of Systematic Review Center for Laboratory Animal Experimentation (SYRCLE). Results Initial search yielded 432 articles. After exclusion of non-original articles, 20 were included in this review. Of these, all studies examined bacterial-type strains only. There were neither relevant in vivo nor clinical studies. The SYRCLE scores ranged from to 5 to 7, with an average of 5.9. This implies a moderate risk of bias. sRNAs influenced the antibiotics susceptibility through modulation of gene expression relevant to efflux pumps, cell wall synthesis, and membrane proteins. Conclusion Preclinical studies on bacterial-type strains suggest that modulation of sRNAs could enhance bacterial susceptibility to antibiotics. Further studies on clinical isolates and in vivo models are needed to elucidate the therapeutic value of sRNA modulation on treatment of multidrug-resistant bacterial infection. PMID:29290689

Prevalence of gastrointestinal bacterial pathogens in a population of zoo animals.

PubMed

Stirling, J; Griffith, M; Blair, I; Cormican, M; Dooley, J S G; Goldsmith, C E; Glover, S G; Loughrey, A; Lowery, C J; Matsuda, M; McClurg, R; McCorry, K; McDowell, D; McMahon, A; Cherie Millar, B; Nagano, Y; Rao, J R; Rooney, P J; Smyth, M; Snelling, W J; Xu, J; Moore, J E

2008-04-01

Faecal prevalence of gastrointestinal bacterial pathogens, including Campylobacter, Escherichia coli O157:H7, Salmonella, Shigella, Yersinia, as well as Arcobacter, were examined in 317 faecal specimens from 44 animal species in Belfast Zoological Gardens, during July-September 2006. Thermophilic campylobacters including Campylobacter jejuni, Campylobacter coli and Campylobacter lari, were the most frequently isolated pathogens, where members of this genus were isolated from 11 animal species (11 of 44; 25%). Yersinia spp. were isolated from seven animal species (seven of 44; 15.9%) and included, Yersinia enterocolitica (five of seven isolates; 71.4%) and one isolate each of Yersinia frederiksenii and Yersinia kristensenii. Only one isolate of Salmonella was obtained throughout the entire study, which was an isolate of Salmonella dublin (O 1,9,12: H g, p), originating from tiger faeces after enrichment. None of the animal species found in public contact areas of the zoo were positive for any gastrointestinal bacterial pathogens. Also, water from the lake in the centre of the grounds, was examined for the same bacterial pathogens and was found to contain C. jejuni. This study is the first report on the isolation of a number of important bacterial pathogens from a variety of novel host species, C. jejuni from the red kangaroo (Macropus rufus), C. lari from a maned wolf (Chrysocyon brachyurus), Y. kristensenii from a vicugna (Vicugna vicugna) and Y. enterocolitica from a maned wolf and red panda (Ailurus fulgens). In conclusion, this study demonstrated that the faeces of animals in public contact areas of the zoo were not positive for the bacterial gastrointestinal pathogens examined. This is reassuring for the public health of visitors, particularly children, who enjoy this educational and recreational resource.

Steroids in bacterial meningitis: yes.

PubMed

Benninger, Felix; Steiner, Israel

2013-02-01

Bacterial meningitis is an infectious condition associated with severe morbidity and mortality, even with rapid diagnosis and appropriate antibiotic therapy. Despite decrease in the rate of bacterial meningitis brought about by vaccination programs against Haemophilus influenzae type-B and Streptococcus pneumonia, the incidence of meningitis is still unacceptably high and acute treatment remains the mainstay of therapy. The infection is accompanied by intense inflammatory response, which may carry deleterious effects upon the tissue. This led to the possibility of adjuvant corticosteroid therapy, as an anti-inflammatory agent, in bacterial meningitis. The debate focuses on the rational and evidence supporting and refuting such an approach.

Indoor air bacterial load and antibiotic susceptibility pattern of isolates in operating rooms and surgical wards at jimma university specialized hospital, southwest ethiopia.

PubMed

Genet, Chalachew; Kibru, Gebre; Tsegaye, Wondewosen

2011-03-01

Surgical site infection is the second most common health care associated infection. One of the risk factors for such infection is bacterial contamination of operating rooms' and surgical wards' indoor air. In view of that, the microbiological quality of air can be considered as a mirror of the hygienic condition of these rooms. Thus, the objective of this study was to determine the bacterial load and antibiotic susceptibility pattern of isolates in operating rooms' and surgical wards' indoor air of Jimma University Specialized Hospital. A cross sectional study was conducted to measure indoor air microbial quality of operating rooms and surgical wards from October to January 2009/2010 on 108 indoor air samples collected in twelve rounds using purposive sampling technique by Settle Plate Method (Passive Air Sampling following 1/1/1 Schedule). Sample processing and antimicrobial susceptibility testing were done following standard bacteriological techniques. The data was analyzed using SPSS version 16 and interpreted according to scientifically determined baseline values initially suggested by Fisher. The mean aerobic colony counts obtained in OR-1(46cfu/hr) and OR-2(28cfu/hr) was far beyond the set 5-8cfu/hr acceptable standards for passive room. Similarly the highest mean aerobic colony counts of 465cfu/hr and 461cfu/hr were observed in Female room-1 and room-2 respectively when compared to the acceptable range of 250-450cfu/hr. In this study only 3 isolates of S. pyogenes and 48 isolates of S. aureus were identified. Over 66% of S. aureus was identified in Critical Zone of Operating rooms. All isolates of S. aureus showed 100% and 82.8% resistance to methicillin and ampicillin respectively. Higher degree of aerobic bacterial load was measured from operating rooms' and surgical wards' indoor air. Reducing foot trafficking, improving the ventilation system and routine cleaning has to be made to maintain the aerobic bacteria load with in optimal level.

Adenylate Kinase Release as a High-Throughput-Screening-Compatible Reporter of Bacterial Lysis for Identification of Antibacterial Agents

PubMed Central

Jacobs, Anna C.; DiDone, Louis; Jobson, Jennielle; Sofia, Madeline K.

2013-01-01

Adenylate kinase (AK) is a ubiquitous intracellular enzyme that is released into the extracellular space upon cell lysis. We have shown that AK release serves as a useful reporter of bactericidal agent activity and can be exploited for antimicrobial screening purposes. The AK assay exhibits improved sensitivity over that of growth-based assays and can detect agents that are active against bacteria in clinically relevant growth states that are difficult to screen using conventional approaches, such as small colony variants (SCV) and bacteria within established biofilms. The usefulness of the AK assay was validated by screening a library of off-patent drugs for agents that exhibit antimicrobial properties toward a variety of bacterial species, including Escherichia coli and all members of the “ESKAPE” pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species). The assay detected antibiotics within the library that were expected to be active against the organism screened. Moreover, 38 drugs with no previously reported antibacterial activity elicited AK release. Four of these were acquired, and all were verified to exhibit antimicrobial activity by standard susceptibility testing. Two of these molecules were further characterized. The antihistamine, terfenadine, was active against S. aureus planktonic, SCV population, and biofilm-associated cells. Tamoxifen, an estrogen receptor antagonist, was active toward E. faecium in vitro and also reduced E. faecium pathogenesis in a Galleria mellonella infection model. Our data demonstrate that the AK assay provides an attractive screening approach for identifying new antimicrobial agents. Further, terfenadine and tamoxifen may represent novel antimicrobial drug development scaffolds. PMID:23027196

[Algicidal activity against red-tide algaes by marine bacterial strain N3 isolated from a HABs area, southern China].

PubMed

Shi, Rong-jun; Huang, Hong-hui; Qi, Zhan-hui; Hu, Wei-an; Tian, Zi-yang; Dai, Ming

2013-05-01

A marine algicidal bacterium N3 was isolated from a HABs area in Mirs Bay, a subtropical bay, in southern China. Algicidal activity and algicidal mode against Phaeodactylum tricornutum, Scrippsiella trochoidea, Prorocentrum micans and Skeletonema costatum were observed by the liquid infection method. The results showed that there were no algicidal activities against P. tricornutum and S. costatum. However, when the bacterial volume fractions were 2% and 10% , S. trochoidea and P. micans could be killed, respectively. S. trochoidea cells which were exposed to strain N3 became irregular in shape and the cellular components lost their integrity and were decomposed. While, the P. micans cells became inflated and the cellular components aggregated, followed by cell lysis. Strain N3 killed S. trochoidea and P. micans directly, and the algicidal activities of the bacterial strain N3 was concentration-dependent. To S. trochoidea, 2% (V/V) of bacteria in algae showed the strongest algicidal activity, all of the S. trochoidea cells were killed within 120 h. But the growth rates of cells, in the 1% and 0. 1% treatment groups, were only slightly lower than that in the control group. In all treatment groups, the densities of strain N3 were in declining trends. While, to P. micans, 10% and 5% of bacteria in algae showed strong algicidal activities, 78% and 70% of the S. trochoidea were killed within 120 h, respectively. However, the number of S. trochoidea after exposure to 1% of bacterial cultures still increased up to 5 incubation days. And in the three treatment groups, the densities of strain N3 experienced a decrease process. The isolated strain N3 was identified as Bacillus sp. by morphological observation, physiological and biochemical characterization, and homology comparisons based on 16S rRNA sequences.

Study of bacterial meningitis in children below 5 years with comparative evaluation of gram staining, culture and bacterial antigen detection.

PubMed

Yadhav Ml, Kala

2014-04-01

Bacterial meningitis is one of the most serious infections seen in infants and children, which is associated with acute complications and chronic morbidity. Infections of Central Nervous System (CNS) still dominate the scene of childhood neurological disorders in most of the developing tropical countries. To isolate, identify and determine the antibiotic susceptibility patterns of pathogens associated with bacterial meningitis. We also aimed to comparatively evaluate of Gram staining, culture and bacterial antigen detection in cerebrospinal fluid samples. Present comparative study included 100 CSF samples of children below the age of 5 years, who were clinically suspected meningitis cases. The samples were subjected to Gram staining, culture and Latex agglutination test (LAT). The organisms isolated in the study were characterized and antibiotic susceptibility test was done according to standard guidelines. It was done by using Gaussian test. Of the 100 cases, 24 were diagnosed as Acute bacterial meningitis (ABM) cases by. Gram staining, culture and latex agglutination test. 21 (87.5%) cases were culture positive, with 2 cases being positive for polymicrobial isolates. Gram staining was positive in 17 (70.53%) cases and LAT was positive in 18 (33.33%) cases. Streptococcus pneumoniae was the predominant organism which was isolated and it was sensitive to antibiotics. In the present study, male to female ratio was 1.27:1, which showed a male preponderance. With the combination of Gram staining, culture, and LAT, 100% sensitivity and specificity can be achieved (p < 0.001). Gram staining and LAT can detect 85% of cases of ABM. Bacterial meningitis is a medical emergency and making an early diagnosis and providing treatment early are life saving and they reduce chronic morbidity.

A New Pharmacological Agent (AKB-4924) Stabilizes Hypoxia Inducible Factor (HIF) and Increases Skin Innate Defenses Against Bacterial Infection

PubMed Central

Okumura, Cheryl Y.M.; Hollands, Andrew; Tran, Dan N.; Olson, Joshua; Dahesh, Samira; von Köckritz-Blickwede, Maren; Thienphrapa, Wdee; Corle, Courtney; Jeung, Seung Nam; Kotsakis, Anna; Shalwitz, Robert A.; Johnson, Randall S.; Nizet, Victor

2013-01-01

Hypoxia inducible factor-1 (HIF-1) is a transcription factor that is a major regulator of energy homeostasis and cellular adaptation to low oxygen stress. HIF-1 is also activated in response to bacterial pathogens and supports the innate immune response of both phagocytes and keratinocytes. In this work, we show that a new pharmacological compound AKB-4924 (Akebia Therapeutics) increases HIF-1α levels and enhances the antibacterial activity of phagocytes and keratinocytes against both methicillin-sensitive and -resistant strains of Staphylococcus aureus in vitro. AKB-4924 is also effective in stimulating the killing capacity of keratinocytes against the important opportunistic skin pathogens Pseudomonas aeruginosa and Acinitobacter baumanii. The effect of AKB-4924 is mediated through the activity of host cells, as the compound exerts no direct antimicrobial activity. Administered locally as a single agent, AKB-4924 limits S. aureus proliferation and lesion formation in a mouse skin abscess model. This approach to pharmacologically boost the innate immune response via HIF-1 stabilization may serve as a useful adjunctive treatment for antibiotic-resistant bacterial infections. PMID:22371073

Bacterial community profiling of milk samples as a means to understand culture-negative bovine clinical mastitis.

PubMed

Kuehn, Joanna S; Gorden, Patrick J; Munro, Daniel; Rong, Ruichen; Dong, Qunfeng; Plummer, Paul J; Wang, Chong; Phillips, Gregory J

2013-01-01

Inflammation and infection of bovine mammary glands, commonly known as mastitis, imposes significant losses each year in the dairy industry worldwide. While several different bacterial species have been identified as causative agents of mastitis, many clinical mastitis cases remain culture negative, even after enrichment for bacterial growth. To understand the basis for this increasingly common phenomenon, the composition of bacterial communities from milk samples was analyzed using culture independent pyrosequencing of amplicons of 16S ribosomal RNA genes (16S rDNA). Comparisons were made of the microbial community composition of culture negative milk samples from mastitic quarters with that of non-mastitic quarters from the same animals. Genomic DNA from culture-negative clinical and healthy quarter sample pairs was isolated, and amplicon libraries were prepared using indexed primers specific to the V1-V2 region of bacterial 16S rRNA genes and sequenced using the Roche 454 GS FLX with titanium chemistry. Evaluation of the taxonomic composition of these samples revealed significant differences in the microbiota in milk from mastitic and healthy quarters. Statistical analysis identified seven bacterial genera that may be mainly responsible for the observed microbial community differences between mastitic and healthy quarters. Collectively, these results provide evidence that cases of culture negative mastitis can be associated with bacterial species that may be present below culture detection thresholds used here. The application of culture-independent bacterial community profiling represents a powerful approach to understand long-standing questions in animal health and disease.

Fluoroquinolone antimicrobial agents.

PubMed Central

Wolfson, J S; Hooper, D C

1989-01-01

The fluoroquinolones, a new class of potent orally absorbed antimicrobial agents, are reviewed, considering structure, mechanisms of action and resistance, spectrum, variables affecting activity in vitro, pharmacokinetic properties, clinical efficacy, emergence of resistance, and tolerability. The primary bacterial target is the enzyme deoxyribonucleic acid gyrase. Bacterial resistance occurs by chromosomal mutations altering deoxyribonucleic acid gyrase and decreasing drug permeation. The drugs are bactericidal and potent in vitro against members of the family Enterobacteriaceae, Haemophilus spp., and Neisseria spp., have good activity against Pseudomonas aeruginosa and staphylococci, and (with several exceptions) are less potent against streptococci and have fair to poor activity against anaerobic species. Potency in vitro decreases in the presence of low pH, magnesium ions, or urine but is little affected by different media, increased inoculum, or serum. The effects of the drugs in combination with a beta-lactam or aminoglycoside are often additive, occasionally synergistic, and rarely antagonistic. The agents are orally absorbed, require at most twice-daily dosing, and achieve high concentrations in urine, feces, and kidney and good concentrations in lung, bone, prostate, and other tissues. The drugs are efficacious in treatment of a variety of bacterial infections, including uncomplicated and complicated urinary tract infections, bacterial gastroenteritis, and gonorrhea, and show promise for therapy of prostatitis, respiratory tract infections, osteomyelitis, and cutaneous infections, particularly when caused by aerobic gram-negative bacilli. Fluoroquinolones have also proved to be efficacious for prophylaxis against travelers' diarrhea and infection with gram-negative bacilli in neutropenic patients. The drugs are effective in eliminating carriage of Neisseria meningitidis. Patient tolerability appears acceptable, with gastrointestinal or central nervous

Epidemiology, Diagnosis, and Antimicrobial Treatment of Acute Bacterial Meningitis

PubMed Central

Brouwer, Matthijs C.; Tunkel, Allan R.; van de Beek, Diederik

2010-01-01

Summary: The epidemiology of bacterial meningitis has changed as a result of the widespread use of conjugate vaccines and preventive antimicrobial treatment of pregnant women. Given the significant morbidity and mortality associated with bacterial meningitis, accurate information is necessary regarding the important etiological agents and populations at risk to ascertain public health measures and ensure appropriate management. In this review, we describe the changing epidemiology of bacterial meningitis in the United States and throughout the world by reviewing the global changes in etiological agents followed by specific microorganism data on the impact of the development and widespread use of conjugate vaccines. We provide recommendations for empirical antimicrobial and adjunctive treatments for clinical subgroups and review available laboratory methods in making the etiological diagnosis of bacterial meningitis. Finally, we summarize risk factors, clinical features, and microbiological diagnostics for the specific bacteria causing this disease. PMID:20610819

Diversity of bacteria associated with Bursaphelenchus xylophilus and other nematodes isolated from Pinus pinaster trees with pine wilt disease.

PubMed

Proença, Diogo Neves; Francisco, Romeu; Santos, Clara Vieira; Lopes, André; Fonseca, Luís; Abrantes, Isabel M O; Morais, Paula V

2010-12-09

The pinewood nematode (PWN), Bursaphelenchus xylophilus, has been thought to be the only causal agent of pine wilt disease (PWD), however, since bacteria have been suggested to play a role in PWD, it is important to know the diversity of the microbial community associated to it. This study aimed to assess the microbial community associated with B. xylophilus and with other nematodes isolated from pine trees, Pinus pinaster, with PWD from three different affected forest areas in Portugal. One hundred and twenty three bacteria strains were isolated from PWN and other nematodes collected from 14 P. pinaster. The bacteria strains were identified by comparative analysis of the 16S rRNA gene partial sequence. All except one gram-positive strain (Actinobacteria) belonged to the gram-negative Beta and Gammaproteobacteria. Most isolates belonged to the genus Pseudomonas, Burkholderia and to the family Enterobacteriaceae. Species isolated in higher percentage were Pseudomonas lutea, Yersinia intermedia and Burkholderia tuberum. The major bacterial population associated to the nematodes differed according to the forest area and none of the isolated bacterial species was found in all different forest areas. For each of the sampled areas, 60 to 100% of the isolates produced siderophores and at least 40% produced lipases. The ability to produce siderophores and lipases by most isolates enables these bacteria to have a role in plant physiological response. This research showed a high diversity of the microbial community associated with B. xylophilus and other nematodes isolated from P. pinaster with PWD.

Antibacterial and antiparasitic activity of oleanolic acid and its glycosides isolated from marigold (Calendula officinalis).

PubMed

Szakiel, Anna; Ruszkowski, Dariusz; Grudniak, Anna; Kurek, Anna; Wolska, Krystyna I; Doligalska, Maria; Janiszowska, Wirginia

2008-11-01

The antibacterial and antiparasitic activities of free oleanolic acid and its glucosides and glucuronides isolated from marigold (Calendula officinalis) were investigated. The MIC of oleanolic acid and the effect on bacterial growth were estimated by A600 measurements. Oleanolic acid's influence on bacterial survival and the ability to induce autolysis were measured by counting the number of cfu. Cell morphology and the presence of endospores were observed under electron and light microscopy, respectively. Oleanolic acid inhibited bacterial growth and survival, influenced cell morphology and enhanced the autolysis of Gram-positive bacteria suggesting that bacterial envelopes are the target of its activity. On the other hand, glycosides of oleanolic acid inhibited the development of L3 Heligmosomoides polygyrus larvae, the infective stage of this intestinal parasitic nematode. In addition, both oleanolic acid and its glycosides reduced the rate of L3 survival during prolonged storage, but only oleanolic acid glucuronides affected nematode infectivity. The presented results suggest that oleanolic acid and its glycosides can be considered as potential therapeutic agents.

A primary assessment of the endophytic bacterial community in a xerophilous moss (Grimmia montana) using molecular method and cultivated isolates

PubMed Central

Liu, Xiao Lei; Liu, Su Lin; Liu, Min; Kong, Bi He; Liu, Lei; Li, Yan Hong

2014-01-01

Investigating the endophytic bacterial community in special moss species is fundamental to understanding the microbial-plant interactions and discovering the bacteria with stresses tolerance. Thus, the community structure of endophytic bacteria in the xerophilous moss Grimmia montana were estimated using a 16S rDNA library and traditional cultivation methods. In total, 212 sequences derived from the 16S rDNA library were used to assess the bacterial diversity. Sequence alignment showed that the endophytes were assigned to 54 genera in 4 phyla (Proteobacteria, Firmicutes, Actinobacteria and Cytophaga/Flexibacter/Bacteroids). Of them, the dominant phyla were Proteobacteria (45.9%) and Firmicutes (27.6%), the most abundant genera included Acinetobacter, Aeromonas, Enterobacter, Leclercia, Microvirga, Pseudomonas, Rhizobium, Planococcus, Paenisporosarcina and Planomicrobium. In addition, a total of 14 species belonging to 8 genera in 3 phyla (Proteobacteria, Firmicutes, Actinobacteria) were isolated, Curtobacterium, Massilia, Pseudomonas and Sphingomonas were the dominant genera. Although some of the genera isolated were inconsistent with those detected by molecular method, both of two methods proved that many different endophytic bacteria coexist in G. montana. According to the potential functional analyses of these bacteria, some species are known to have possible beneficial effects on hosts, but whether this is the case in G. montana needs to be confirmed. PMID:24948927

Evaluation of insecticidal activity of a bacterial strain, Serratia sp. EML-SE1 against diamondback moth.

PubMed

Jeong, Hyung Uk; Mun, Hye Yeon; Oh, Hyung Keun; Kim, Seung Bum; Yang, Kwang Yeol; Kim, Iksoo; Lee, Hyang Burm

2010-08-01

To identify novel bioinsecticidal agents, a bacterial strain, Serratia sp. EML-SE1, was isolated from a dead larva of the lepidopteran diamondback moth (Plutella xylostella) collected from a cabbage field in Korea. In this study, the insecticidal activity of liquid cultures in Luria-Bertani broth (LBB) and nutrient broth (NB) of a bacterial strain, Serratia sp. EML-SE1 against thirty 3rd and 4th instar larvae of the diamondback moth was investigated on a Chinese cabbage leaf housed in a round plastic cage (Ø 10 x 6 cm). 72 h after spraying the cabbage leaf with LBB and NB cultures containing the bacterial strain, the mortalities of the larvae were determined to be 91.7% and 88.3%, respectively. In addition, the insecticidal activity on potted cabbage containing 14 leaves in a growth cage (165 x 83 x 124 cm) was found to be similar to that of the plastic cage experiment. The results of this study provided valuable information on the insecticidal activity of the liquid culture of a Serratia species against the diamondback moth.

Microbial population dynamics in the sediments of a eutrophic lake (Aydat, France) and characterization of some heterotrophic bacterial isolates.

PubMed

Mallet, C; Basset, M; Fonty, G; Desvilettes, C; Bourdier, G; Debroas, D

2004-07-01

The bacterial populations of anoxic sediments in a eutrophic lake (Aydat, Puy-de-Dôme-France) were studied by phospholipid fatty acid analysis (PLFA) and also by culturing heterotrophic bacteria under strictly anaerobic conditions. The mean PLFA concentrations of prokaryotes and microeukaryotes were 5.7 +/- 2.9 mgC g(-1) DS and 9.6 +/- 6.7 mgC g(-1) DS, respectively. The analysis of bacterial PLFA markers was used to determine the dynamics of the Gram-positive and Gram-negative species of anaerobic bacteria, Clostridiae, and sulfate-reducing bacteria. Throughout the sampling period the concentrations of i15:0 (from 20 nmol g(-1) DS to 130 nmol g(-1) DS), markers of Gram-positive bacteria, were higher than those for Gram-negative bacteria. The dynamics of Clostridiae (Cy15:0) paralleled those of sulfate-reducing bacteria that were marked by i17:1omega7. Partial 16S rDNA sequencing and the physiological study of the various fermenting strains, whose abundance in the superficial sediment layer was 1.1 +/- 0.4 x 10(6) cells mL(-1), showed that all the isolates belonged to the Clostridiae and related taxa ( Lactosphaera pasteurii, Clostridium vincentii, C. butyricum, C. algidixylanolyticum, C. puniceum, C. lituseburense, and C. gasigenes). All the isolates were capable of metabolizing a wide range of organic substrates.

Biodegradation of marine crude oil pollution using a salt-tolerant bacterial consortium isolated from Bohai Bay, China.

PubMed

Li, Xinfei; Zhao, Lin; Adam, Mohamed

2016-04-15

This study aims at constructing an efficient bacterial consortium to biodegrade crude oil spilled in China's Bohai Sea. In this study, TCOB-1 (Ochrobactrum), TCOB-2 (Brevundimonas), TCOB-3 (Brevundimonas), TCOB-4 (Bacillus) and TCOB-5 (Castellaniella) were isolated from Bohai Bay. Through the analysis of hydrocarbon biodegradation, TCOB-4 was found to biodegrade more middle-chain n-alkanes (from C17 to C23) and long-chain n-alkanes (C31-C36). TCOB-5 capable to degrade more n-alkanes including C24-C30 and aromatics. On the basis of complementary advantages, TCOB-4 and TCOB-5 were chosen to construct a consortium which was capable of degrading about 51.87% of crude oil (2% w/v) after 1week of incubation in saline MSM (3% NaCl). It is more efficient compared with single strain. In order to biodegrade crude oil, the construction of bacterial consortia is essential and the principle of complementary advantages could reduce competition between microbes. Copyright © 2016. Published by Elsevier Ltd.

Draft Genome Sequences of Two Isolates of Colletotrichum lindemuthianum, the Causal Agent of Anthracnose in Common Beans.

PubMed

de Queiroz, Casley Borges; Correia, Hilberty L Nunes; Menicucci, Renato Pedrozo; Vidigal, Pedro M Pereira; de Queiroz, Marisa Vieira

2017-05-04

Colletotrichum lindemuthianum is the causal agent of anthracnose in common beans, one of the main limiting factors of their culture. Here, we report for the first time, to our knowledge, a draft of the complete genome sequences of two isolates belonging to 83.501 and 89 A 2 2-3 of C. lindemutuianum . Copyright © 2017 de Queiroz et al.

Novel cajaninstilbene acid derivatives as antibacterial agents.

PubMed

Geng, Zhi-Zhong; Zhang, Jian-Jun; Lin, Jing; Huang, Mei-Yan; An, Lin-Kun; Zhang, Hong-Bin; Sun, Ping-Hua; Ye, Wen-Cai; Chen, Wei-Min

2015-07-15

Discovery of novel antibacterial agents with new structural scaffolds that combat drug-resistant pathogens is an urgent task. Cajaninstilbene acid, which is isolated from pigeonpea leaves, has shown antibacterial activity. In this study, a series of cajaninstilbene acid derivatives were designed and synthesized. The antibacterial activities of these compounds against gram-negative and gram-positive bacteria, as well as nine strains of methicillin-resistant staphylococcus aureus (MRSA) bacteria are evaluated，and the related structure-activity relationships are discussed. Assays suggest that some of the synthetic cajaninstilbene acid derivatives exhibit potent antibacterial activity against gram-positive bacterial strains and MRSA. Among these compounds, 5b, 5c, 5j and 5k show better antibacterial activity than the positive control compounds. The results of MTT assays illustrate the low cytotoxicity of the active compounds. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Identification of bacteria isolated from veterinary clinical specimens using MALDI-TOF MS.

PubMed

Pavlovic, Melanie; Wudy, Corinna; Zeller-Peronnet, Veronique; Maggipinto, Marzena; Zimmermann, Pia; Straubinger, Alix; Iwobi, Azuka; Märtlbauer, Erwin; Busch, Ulrich; Huber, Ingrid

2015-01-01

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently emerged as a rapid and accurate identification method for bacterial species. Although it has been successfully applied for the identification of human pathogens, it has so far not been well evaluated for routine identification of veterinary bacterial isolates. This study was performed to compare and evaluate the performance of MALDI-TOF MS based identification of veterinary bacterial isolates with commercially available conventional test systems. Discrepancies of both methods were resolved by sequencing 16S rDNA and, if necessary, the infB gene for Actinobacillus isolates. A total of 375 consecutively isolated veterinary samples were collected. Among the 357 isolates (95.2%) correctly identified at the genus level by MALDI-TOF MS, 338 of them (90.1% of the total isolates) were also correctly identified at the species level. Conventional methods offered correct species identification for 319 isolates (85.1%). MALDI-TOF identification therefore offered more accurate identification of veterinary bacterial isolates. An update of the in-house mass spectra database with additional reference spectra clearly improved the identification results. In conclusion, the presented data suggest that MALDI-TOF MS is an appropriate platform for classification and identification of veterinary bacterial isolates.

Bacteriological and virulence study of a Mycobacterium chimaera isolate from a patient in China.

PubMed

Liu, Guan; Chen, Su-Ting; Yu, Xia; Li, Yu-Xun; Ling, Ying; Dong, Ling-Ling; Zheng, Su-Hua; Huang, Hai-Rong

2015-04-01

A clinical isolate from a patient was identified as Mycobacterium chimaera, a recently identified species of nontuberculous Mycobacteria. The biochemical and molecular identity, drug sensitivity and virulence of this isolated strain were investigated. 16S rRNA, the 16S-23S ITS, hsp65 and rpoB were amplified, and their sequence similarities with other mycobacteria were analyzed. The minimum inhibitory concentrations of 22 anti-microbial agents against this isolate were established, and the virulence of the isolate was evaluated by intravenous injection into C57BL/6 mice using Mycobacterium tuberculosis H37Rv as a control strain. Growth and morphological characteristics and mycolic acid profile analysis revealed that this isolated strain was a member of the Mycobacterium avium complex. BLAST analysis of the amplified sequences showed that the isolated strain was closely related to M. chimaera. Susceptibility testing showed that the isolate was sensitive to rifabutin, rifapentine, clarithromycin, azithromycin, imipenem and cefoxitin. Bacterial load determination and tissue histopathology of the infected mice indicated that the isolate was highly virulent. The first case of M. chimaera infection in China was evaluated. The information derived from this case may offer valuable guidance for clinical diagnosis and treatment.

Towards Defining the Ecological Niches of Novel Coastal Gulf of Mexico Bacterial Isolates

NASA Astrophysics Data System (ADS)

Henson, M. W.; Thrash, C.; Nall, E.

2016-02-01

The study of microbial contributions to biogeochemistry is critical to understanding the cycles of fundamental compounds and gain predictive capabilities in a changing environment. Such study requires observation of microbial communities and genetics in nature, coupled with experimental testing of hypotheses both in situ and in laboratory settings. This study combines dilution-to-extinction based high-throughput culturing (HTC) with cultivation-independent and geochemical measurements to define potential ecological niches of novel bacterial isolates from the coastal northern Gulf of Mexico (cnGOM). Here we report findings from the first of a three-year project. In total, 43 cultures from seven HTC experiments were capable of being repeatedly transferred. Sanger sequencing of the 16S rRNA gene identified these isolates as belonging to the phyla Gammaproteobacteria, Alphaproteobacteria, Actinobacteria, and Betaproteobacteria. Eight are being genome sequenced, with two selected for further physiological characterization due to their phylogenic novelty and potential ecological significance. Strain LSUCC101 likely represents a novel family of Gammaproteobacteria (best blast hit to a cultured representative showed 91% sequence identity) and strain LSUCC96 belongs to the OM252 clade, with the Hawaiian isolate HIMB30 as its closest relative. Both are small (0.3-0.5 µm) cocci. The environmental importance of both LSUCC101 and LSUCC96 was illustrated by their presence within the top 30 OTU0.03 of cnGOM 16S rRNA gene datasets as well as within clone libraries from coastal regions around the world. Ongoing work is determining growth efficiencies, substrate utilization profiles, and metabolic potential to elucidate the roles of these organisms in the cnGOM. Comparative genomics will examine the evolutionary divergence of these organisms from their closest neighbors, and metagenomic recruitment to genomes will help identify strain-based variation from different coastal regions.

Growth Inhibition of Beauveria bassiana by Bacteria Isolated from the Cuticular Surface of the Corn Leafhopper, Dalbulus maidis and the Planthopper, Delphacodes kuscheli, Two Important Vectors of Maize Pathogens

PubMed Central

Toledo, A.V.; Alippi, A.M.; de Remes Lenicov, A.M.M.

2011-01-01

The phytosanitary importance of the corn leafhopper, Dalbulus maidis (De Long and Wolcott) (Hemiptera: Cicadellidae) and the planthopper, Delphacodes kuscheli Fennah (Hemiptera: Delphacidae) lies in their ability to transmit phloem-associated plant pathogens, mainly viruses and mollicutes, and to cause considerable mechanical damage to corn plants during feeding and oviposition. Fungi, particularly some members of the Ascomycota, are likely candidates for biocontrol agents against these insect pests, but several studies revealed their failure to invade the insect cuticle possibly because of the presence of inhibitory compounds such as phenols, quinones, and lipids and also by the antibiosis effect of the microbiota living on the cuticular surface of the host. The present work aims to understand interactions between the entomopathogenic fungus Beauveria bassiana (Balsamao-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae) and bacterial antagonists isolated from the cuticular surface of D. maidis and D. kuscheli. A total of 155 bacterial isolates were recovered from the insect's cuticle and tested against B. bassiana. Ninety-one out of 155 strains inhibited the growth of B. bassiana. Bacterial strains isolated from D. maidis were significantly more antagonistic against B. bassiana than those isolates from D. kuscheli. Among the most effective antagonistic strains, six isolates of Bacillus thuringiensis Berliner (Bacillales: Bacillaeae (after B. subtilis)), one isolate of B. mycoides Flügge, eight isolates of B. megaterium de Bary, five isolates of B.pumilus Meyer and Gottheil, one isolate of B. licheniformis (Weigmann) Chester, and four isolates of B. subtilis (Ehrenberg) Cohn were identified. PMID:21529147

Effect of fluorescent pseudomonades and Trichoderma sp. and their combination with two chemicals on Penicillium digitatum caused agent of citrus green mold.

PubMed

Zamani, M; Tehrani, A Sharifi; Ahmadzadeh, M; Abadi, A Alizadeh Ali

2006-01-01

Citrus green mold (Penicillium digitatum) causes economic losses. Chemical fungicides such as imazalil provide the primary means for controlling green mold decay of citrus fruits. Continuous use of fungicides has faced two major obstacles- increasing public concern regarding contamination of perishables with fungicidal residues, and proliferation of resistance in the pathogen populations. The aim of this research was to determine if the attacks of green mold on orange could be reduced by usage of biocontrol agent alone or in combination with low dosage of imazalil or sodium bicarbonate. Pseudomonas fluorescens isolate PN, P. fluorescens isolate PS and Trichoderma virens isolate TE were evaluated as potential biological agents for control of green mold of oranges caused by P. digitatum. Increasing concentration of SB decreased spore germination of P. digitatum. In laboratory tests, a cell suspension (10(8) cells per ml.) of bacterial strains reduced the incidence of green mold. On fruits surface biocontrol activity of antagonistic isolates was significantly increased when combined with low dosage of imazalil (500ppm) or sodium carbonate (5%). Effect of Trichoderma virens on controlling P. digitatum was better than others with or without these chemicals.

Induction of a Tier-1-Like Phenotype in Diverse Tier-2 Isolates by Agents That Guide HIV-1 Env to Perturbation-Sensitive, Nonnative States.

PubMed

Johnson, Jacklyn; Zhai, Yinjie; Salimi, Hamid; Espy, Nicole; Eichelberger, Noah; DeLeon, Orlando; O'Malley, Yunxia; Courter, Joel; Smith, Amos B; Madani, Navid; Sodroski, Joseph; Haim, Hillel

2017-08-01

The envelope glycoproteins (Envs) on the surfaces of HIV-1 particles are targeted by host antibodies. Primary HIV-1 isolates demonstrate different global sensitivities to antibody neutralization; tier-1 isolates are sensitive, whereas tier-2 isolates are more resistant. Single-site mutations in Env can convert tier-2 into tier-1-like viruses. We hypothesized that such global change in neutralization sensitivity results from weakening of intramolecular interactions that maintain Env integrity. Three strategies commonly applied to perturb protein structure were tested for their effects on global neutralization sensitivity: exposure to low temperature, Env-activating ligands, and a chaotropic agent. A large panel of diverse tier-2 isolates from clades B and C was analyzed. Incubation at 0°C, which globally weakens hydrophobic interactions, causes gradual and reversible exposure of the coreceptor-binding site. In the cold-induced state, Envs progress at isolate-specific rates to unstable forms that are sensitive to antibody neutralization and then gradually lose function. Agents that mimic the effects of CD4 (CD4Ms) also induce reversible structural changes to states that exhibit isolate-specific stabilities. The chaotropic agent urea (at low concentrations) does not affect the structure or function of native Env. However, urea efficiently perturbs metastable states induced by cold and CD4Ms and increases their sensitivity to antibody neutralization and their inactivation rates Therefore, chemical and physical agents can guide Env from the stable native state to perturbation-sensitive forms and modulate their stability to bestow tier-1-like properties on primary tier-2 strains. These concepts can be applied to enhance the potency of vaccine-elicited antibodies and microbicides at mucosal sites of HIV-1 transmission. IMPORTANCE An effective vaccine to prevent transmission of HIV-1 is a primary goal of the scientific and health care communities. Vaccine

The potential of compounds isolated from Xylaria spp. as antifungal agents against anthracnose.

PubMed

Elias, Luciana M; Fortkamp, Diana; Sartori, Sérgio B; Ferreira, Marília C; Gomes, Luiz H; Azevedo, João L; Montoya, Quimi V; Rodrigues, André; Ferreira, Antonio G; Lira, Simone P

2018-03-31

Anthracnose is a crop disease usually caused by fungi in the genus Colletotrichum or Gloeosporium. These are considered one of the main pathogens, causing significant economic losses, such as in peppers and guarana. The current forms of control include the use of resistant cultivars, sanitary pruning and fungicides. However, even with the use of some methods of controlling these cultures, the crops are not free of anthracnose. Additionally, excessive application of fungicides increases the resistance of pathogens to agrochemicals and cause harm to human health and the environment. In order to find natural antifungal agents against guarana anthracnose, endophytic fungi were isolated from Amazon guarana. The compounds piliformic acid and cytochalasin D were isolated by chromatographic techniques from two Xylaria spp., guided by assays with Colletotrichum gloeosporioides. The isolated compounds were identified by spectrometric techniques, as NMR and mass spectrometry. This is the first report that piliformic acid and cytochalasin D have antifungal activity against C. gloeosporioides with MIC 2.92 and 2.46μmolmL -1 respectively. Captan and difenoconazole were included as positive controls (MIC 16.63 and 0.02μmolmL -1 , respectively). Thus, Xylaria species presented a biotechnological potential and production of different active compounds which might be promising against anthracnose disease. Copyright © 2018 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

Developing live bacterial vaccines by selecting resistance to antibacterials

USDA-ARS?s Scientific Manuscript database

Four chemicals were used in this study to modify bacterial isolates through chemical-resistance strategy. All bacteria were able to develop high resistance to gossypol. However, none of the gossypol-resistant isolate was attenuated. Although majority of the proflavine hemisulfate-resistant isolates ...

CD28 homodimer interface mimetic peptide acts as a preventive and therapeutic agent in models of severe bacterial sepsis and gram-negative bacterial peritonitis.

PubMed

Ramachandran, Girish; Kaempfer, Raymond; Chung, Chun-Shiang; Shirvan, Anat; Chahin, Abdullah B; Palardy, John E; Parejo, Nicolas A; Chen, Yaping; Whitford, Melissa; Arad, Gila; Hillman, Dalia; Shemesh, Ronen; Blackwelder, William; Ayala, Alfred; Cross, Alan S; Opal, Steven M

2015-03-15

Severe gram-negative bacterial infections and sepsis are major causes of morbidity and mortality. Dysregulated, excessive proinflammatory cytokine expression contributes to the pathogenesis of sepsis. A CD28 mimetic peptide (AB103; previously known as p2TA) that attenuates CD28 signaling and T-helper type 1 cytokine responses was tested for its ability to increase survival in models of polymicrobial infection and gram-negative sepsis. Mice received AB103, followed by an injection of Escherichia coli 0111:B4 lipopolysaccharide (LPS); underwent induction E. coli 018:K1 peritonitis induction, followed by treatment with AB103; or underwent cecal ligation and puncture (CLP), followed by treatment with AB103. The effects of AB103 on factors associated with and the lethality of challenge infections were analyzed. AB103 strongly attenuated induction of tumor necrosis factor α and interleukin 6 (IL-6) by LPS in human peripheral blood mononuclear cells. Receipt of AB103 following intraperitoneal injection of LPS resulted in survival among 73% of CD1 mice (11 of 15), compared with 20% of controls (3 of 15). Suboptimal doses of antibiotic alone protected 20% of mice (1 of 5) from E. coli peritonitis, whereas 100% (15 of 15) survived when AB103 was added 4 hours following infection. Survival among mice treated with AB103 12 hours after CLP was 100% (8 of 8), compared with 17% among untreated mice (1 of 6). In addition, receipt of AB103 12 hours after CLP attenuated inflammatory cytokine responses and neutrophil influx into tissues and promoted bacterial clearance. Receipt of AB103 24 hours after CLP still protected 63% of mice (5 of 8). Single-dose AB103 reduces mortality in experimental models of polymicrobial and gram-negative bacterial infection and sepsis, warranting further studies of this agent in clinical trials. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please

Bacteriophage-like Particles Associated with the Gene Transfer Agent of Methanococcus Voltale PS

NASA Technical Reports Server (NTRS)

Bertani, G.; Eiserling, F.; Pushkin, A.; Gingery, M.

1999-01-01

The methanogenic archaebacterium Methanococus voltae (strain PS) is known to produce a filterable, DNase resistant agent (called VTA, for voltae transfer agent), which carries very small fragments (4,400 base pairs) of bacterial DNA and is able to transduce bacterial genes between derivatives of the strain.

Phytoplankton and bacterial community structures and their interaction during red-tide phenomena

NASA Astrophysics Data System (ADS)

Ismail, Mona Mohamed; Ibrahim, Hassan Abd Allah

2017-09-01

Phytoplankton and bacteria diversity were studied before, during and after red tide phenomena during spring season 2015 in the Eastern Harbour (E.H.) of Alexandria, Egypt. Fifty five species of phytoplankton were identified and represented different distinct classes "Bacillariophyceae; Dinophyceae, Chlorophyceae, Cyanophyceae and Eugelenophyceae". Also, Diatom formed the most dominant group. The average number of the phytoplankton density varied from 4.8 × 104 to 1.1 × 106 cell l-1 during the study period and Skeletonema costatum was the agent causing the red tide. The existence percentages of bacteria ranged from 2.6 to 17.9% on all media tested. The bacterial isolates on the nutrient agar medium represented the highest existence with a total percentage of 43.6%, followed by MSA medium (25.7%), while the lowest percentage was for the AA medium at 7.8%. However, twelve isolates were selected as representative for bacterial community during study interval. Based on the morphological, biochemical, physiological and enzymatic characteristics, the bacterial strains were described. Depending on the 16S rDNA gene sequence, three common antagonists were aligned as: Vibrio toranzoniae strain Vb 10.8, Ruegeria pelagia strain NBRC 102038 and Psychrobacter adeliensis strain DSM 15333. The interaction between these bacteria and S. costatum was studied. The growth of S. costatum was significantly lower whenever each bacterium was present as compared to axenic culture. More specifically, 30% (v/v) of the all tested bacteria showed the strongest algicidal activities, as all S. costatum cells were killed after two days. 10% of R. pelagia and P. adeliensis also showed significant algicidal activities within six days.

Biodegradation of kraft lignin by a newly isolated anaerobic bacterial strain, Acetoanaerobium sp. WJDL-Y2.

PubMed

Duan, J; Huo, X; Du, W J; Liang, J D; Wang, D Q; Yang, S C

2016-01-01

An anaerobic kraft lignin (KL)-degrading bacterial strain was isolated from sludge of a pulp and paper mill. It was characterized as Acetoanaerobium sp. WJDL-Y2 by 16S rRNA gene sequencing. The maximum KL degradation capability of strain Y2 was determined to be 24·9% on a COD basis under an optimal condition with temperature of 31·5°C, initial pH of 6·8 and KL to nitrogen (as NH4 Cl) ratio of 6·5 by mass. Growth kinetic studies showed that the KL tolerance of strain Y2 was relatively high (Ki  = 8120·45 mg l(-1) ). Analysing KL degradation products by GC-MS revealed the formation of low-molecular-weight aromatic compounds (LMWACs), including benzene-propanoic acid, syringic acid and ferulic acid. This indicates that strain Y2 can oxidize lignin structure's p-hydroxyphenyl (H) units, guaiacyl (G) units and syringyl (S). In addition, the inoculated sample also contained low-molecular acid compounds, such as hexanoic acid, adipic acid and 2-hydroxybutyric acid, further validating strain Y2's ability to degrade KL. Kraft lignin containing effluents discharged from pulp and paper industries causes serious environmental pollution in developing countries. Due to the immense environmental adaptability and biochemical versatility, bacterial ligninolytic potential deserve to be studied for application in effluent treatment of pulp and paper industry. In this study, an anaerobic lignin-degrading bacterium, Acetoanaerobium sp. WJDL-Y2 (accession no. KF176997),was isolated from the sludge of a pulp and paper mill. Strain Y2 can play an important role in treating pulp and paper wastewater, as well as breaking down materials for biofuel and chemical production. © 2015 The Society for Applied Microbiology.

Bacterial profile of urinary tract infection and antimicrobial susceptibility pattern among pregnant women attending at Antenatal Clinic in Dil Chora Referral Hospital, Dire Dawa, Eastern Ethiopia

PubMed Central

Derese, Behailu; Kedir, Haji; Teklemariam, Zelalem; Weldegebreal, Fitsum; Balakrishnan, Senthilkumar

2016-01-01

Purpose The aim of this study was to determine the bacterial profile of urinary tract infection (UTI) and antimicrobial susceptibility pattern among pregnant women attending at antenatal clinic in Dil Chora Referral Hospital, Dire Dawa, Eastern Ethiopia. Patients and methods An institutional-based cross-sectional study was conducted from February 18, 2015 to March 25, 2015. Clean-catch midstream urine specimens were collected from 186 pregnant women using sterile containers. Then, culture and antimicrobial susceptibility tests were performed by standard disk diffusion method. Patient information was obtained using pretested structured questionnaire. Data were entered and cleaned using EpiData Version 3 and then exported to Statistical Package for Social Science (Version 16) for further analysis. Results The prevalence of significant bacteriuria was 14%. Gram-negative bacteria were more prevalent (73%). Escherichia coli (34.6%), coagulase-negative staphylococci (19.2%), Pseudomonas aeruginosa (15.4%), and Klebsiella spp. (11.5%) were common bacterial isolates, where most of them were resistant against ampicillin, amoxicillin, tetracycline, trimethoprim–sulfamethoxazole, and chloramphenicol. Multidrug resistance (resistance in ≥2 drugs) was seen in 100% of the isolated bacteria. A majority of the bacterial isolates were sensitive to ciprofloxacin, ceftriaxone, erythromycin, and gentamicin. Conclusion This study found a number of bacterial isolates with very high resistance to the commonly prescribed drugs from pregnant women with and without symptoms of UTI. Therefore, the early routine detection of causative agents of UTI and determining their drug susceptibility pattern are important for pregnant women to avoid complications in mother and fetus. Ciprofloxacin, ceftriaxone, gentamicin, and erythromycin can be used with great care for the empirical treatment of UTI. PMID:26937197

Bacterial endophytes enhance competition by invasive plants.

PubMed

Rout, Marnie E; Chrzanowski, Thomas H; Westlie, Tara K; DeLuca, Thomas H; Callaway, Ragan M; Holben, William E

2013-09-01

Invasive plants can alter soil microbial communities and profoundly alter ecosystem processes. In the invasive grass Sorghum halepense, these disruptions are consequences of rhizome-associated bacterial endophytes. We describe the effects of N2-fixing bacterial strains from S. halepense (Rout and Chrzanowski, 2009) on plant growth and show that bacteria interact with the plant to alter soil nutrient cycles, enabling persistence of the invasive. • We assessed fluxes in soil nutrients for ∼4 yr across a site invaded by S. halepense. We assayed the N2-fixing bacteria in vitro for phosphate solubilization, iron chelation, and production of the plant-growth hormone indole-3-acetic acid (IAA). We assessed the plant's ability to recruit bacterial partners from substrates and vertically transmit endophytes to seeds and used an antibiotic approach to inhibit bacterial activity in planta and assess microbial contributions to plant growth. • We found persistent alterations to eight biogeochemical cycles (including nitrogen, phosphorus, and iron) in soils invaded by S. halepense. In this context, three bacterial isolates solubilized phosphate, and all produced iron siderophores and IAA in vitro. In growth chamber experiments, bacteria were transmitted vertically, and molecular analysis of bacterial community fingerprints from rhizomes indicated that endophytes are also horizontally recruited. Inhibiting bacterial activity with antibiotics resulted in significant declines in plant growth rate and biomass, with pronounced rhizome reductions. • This work suggests a major role of endophytes on growth and resource allocation of an invasive plant. Indeed, bacterial isolate physiology is correlated with invader effects on biogeochemical cycles of nitrogen, phosphate, and iron.

Intraperitoneal inoculation of Haemophilus influenzae local isolates in BALB/c mice model in the presence and absence of virulence enhancement agents.

PubMed

Mojgani, N; Maldjae, V; Rahbar, M; Mirafzali, S M; Khoshnood, S; Hatami, A

2013-01-01

Haemophilus influenzae (Hi), predominantly type b accounts for approximately 4% of cases of community-acquired and nosocomial meningitis, in adults. The objective of this study was to evaluate the pathogenicity of local Hi isolates (type b, f and non-typable) in BALB/c mice in the presence of virulence enhancement agents. Three different concentrations of the Hi isolates were inoculated intraperitoneally in BALB/c mice in the presence of 2% hemoglobin and 4% mucin as virulence enhancing agents (VEA). The ability of the isolates to produce bacteremia, the percent survival and lethal dose (LD50) were recorded in different challenge groups. The 3 Haemophilus influenzae type b (Hib) isolates used in study were able to show virulence in BALB/c mice model only in the presence of VEA and their LD50 decreased significantly when 2% hemoglobin and 4% mucin were used. All survived animals showed bacteremia within 4 h of inoculation which was cleared within 18 h. Significant differences (P<0.01) in the virulence and survival percentage of Hib challenge groups were observed based on their dose of inoculation and VEA. None of the isolates were able to induce infection in the absence of VEA. Non-type b isolates failed to produce disease in the mice models even at the highest inoculated dose (10⁸ cfu) and in the presence of VEA. BALB/c mice appeared suitable for evaluating the virulence of Hib strains, and 2% hemoglobin with 4% mucin an appropriate concentration for inducing infection in this animal model.

Characterization of plant growth promoting traits of bacterial isolates from the rhizosphere of barley (Hordeum vulgare L.) and tomato (Solanum lycopersicon L.) grown under Fe sufficiency and deficiency.

PubMed

Scagliola, M; Pii, Y; Mimmo, T; Cesco, S; Ricciuti, P; Crecchio, C

2016-10-01

Plant Growth Promoting Bacteria (PGPB) are considered a promising approach to replace the conventional agricultural practices, since they have been shown to affect plant nutrient-acquisition processes by influencing nutrient availability in the rhizosphere and/or those biochemical processes determining the uptake at root level of nitrogen (N), phosphorus (P), and iron (Fe), that represent the major constraints for crop productivity worldwide. We have isolated novel bacterial strains from the rhizosphere of barley (Hordeum vulgare L.) and tomato (Solanum lycopersicon L.) plants, previously grown in hydroponic solution (either Fe deficient or Fe sufficient) and subsequently transferred onto an agricultural calcareous soil. PGPB have been identified by molecular tools and characterized for their capacity to produce siderophores and indole-3-acetic acid (IAA), and to solubilize phosphate. Selected bacterial isolates, showing contemporarily high levels of the three activities investigated, were finally tested for their capacity to induce Fe reduction in cucumber roots two isolates, from barley and tomato plants under Fe deficiency, significantly increased the root Fe-chelate reductase activity; interestingly, another isolate enhanced the reduction of Fe-chelate reductase activity in cucumber plant roots, although grown under Fe sufficiency. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

The Rab-binding Profiles of Bacterial Virulence Factors during Infection*

PubMed Central

So, Ernest C.; Schroeder, Gunnar N.; Carson, Danielle; Mattheis, Corinna; Mousnier, Aurélie; Broncel, Malgorzata; Tate, Edward W.; Frankel, Gad

2016-01-01

Legionella pneumophila, the causative agent of Legionnaire's disease, uses its type IV secretion system to translocate over 300 effector proteins into host cells. These effectors subvert host cell signaling pathways to ensure bacterial proliferation. Despite their importance for pathogenesis, the roles of most of the effectors are yet to be characterized. Key to understanding the function of effectors is the identification of host proteins they bind during infection. We previously developed a novel tandem-affinity purification (TAP) approach using hexahistidine and BirA-specific biotinylation tags for isolating translocated effector complexes from infected cells whose composition were subsequently deciphered by mass spectrometry. Here we further advanced the workflow for the TAP approach and determined the infection-dependent interactomes of the effectors SidM and LidA, which were previously reported to promiscuously bind multiple Rab GTPases in vitro. In this study we defined a stringent subset of Rab GTPases targeted by SidM and LidA during infection, comprising of Rab1A, 1B, 6, and 10; in addition, LidA targets Rab14 and 18. Taken together, this study illustrates the power of this approach to profile the intracellular interactomes of bacterial effectors during infection. PMID:26755725

Epidemiological study of hazelnut bacterial blight in central Italy by using laboratory analysis and geostatistics.

PubMed

Lamichhane, Jay Ram; Fabi, Alfredo; Ridolfi, Roberto; Varvaro, Leonardo

2013-01-01

Incidence of Xanthomonas arboricola pv. corylina, the causal agent of hazelnut bacterial blight, was analyzed spatially in relation to the pedoclimatic factors. Hazelnut grown in twelve municipalities situated in the province of Viterbo, central Italy was studied. A consistent number of bacterial isolates were obtained from the infected tissues of hazelnut collected in three years (2010-2012). The isolates, characterized by phenotypic tests, did not show any difference among them. Spatial patterns of pedoclimatic data, analyzed by geostatistics showed a strong positive correlation of disease incidence with higher values of rainfall, thermal shock and soil nitrogen; a weak positive correlation with soil aluminium content and a strong negative correlation with the values of Mg/K ratio. No correlation of the disease incidence was found with soil pH. Disease incidence ranged from very low (<1%) to very high (almost 75%) across the orchards. Young plants (4-year old) were the most affected by the disease confirming a weak negative correlation of the disease incidence with plant age. Plant cultivars did not show any difference in susceptibility to the pathogen. Possible role of climate change on the epidemiology of the disease is discussed. Improved management practices are recommended for effective control of the disease.

Epidemiological Study of Hazelnut Bacterial Blight in Central Italy by Using Laboratory Analysis and Geostatistics

PubMed Central

Lamichhane, Jay Ram; Fabi, Alfredo; Ridolfi, Roberto; Varvaro, Leonardo

2013-01-01

Incidence of Xanthomonas arboricola pv. corylina, the causal agent of hazelnut bacterial blight, was analyzed spatially in relation to the pedoclimatic factors. Hazelnut grown in twelve municipalities situated in the province of Viterbo, central Italy was studied. A consistent number of bacterial isolates were obtained from the infected tissues of hazelnut collected in three years (2010–2012). The isolates, characterized by phenotypic tests, did not show any difference among them. Spatial patterns of pedoclimatic data, analyzed by geostatistics showed a strong positive correlation of disease incidence with higher values of rainfall, thermal shock and soil nitrogen; a weak positive correlation with soil aluminium content and a strong negative correlation with the values of Mg/K ratio. No correlation of the disease incidence was found with soil pH. Disease incidence ranged from very low (<1%) to very high (almost 75%) across the orchards. Young plants (4-year old) were the most affected by the disease confirming a weak negative correlation of the disease incidence with plant age. Plant cultivars did not show any difference in susceptibility to the pathogen. Possible role of climate change on the epidemiology of the disease is discussed. Improved management practices are recommended for effective control of the disease. PMID:23424654

Diverse bacteria isolated from microtherm oil-production water.

PubMed

Sun, Ji-Quan; Xu, Lian; Zhang, Zhao; Li, Yan; Tang, Yue-Qin; Wu, Xiao-Lei

2014-02-01

In total, 435 pure bacterial strains were isolated from microtherm oil-production water from the Karamay Oilfield, Xinjiang, China, by using four media: oil-production water medium (Cai medium), oil-production water supplemented with mineral salt medium (CW medium), oil-production water supplemented with yeast extract medium (CY medium), and blood agar medium (X medium). The bacterial isolates were affiliated with 61 phylogenetic groups that belong to 32 genera in the phyla Actinobacteria, Firmicutes, and Proteobacteria. Except for the Rhizobium, Dietzia, and Pseudomonas strains that were isolated using all the four media, using different media led to the isolation of bacteria with different functions. Similarly, nonheme diiron alkane monooxygenase genes (alkB/alkM) also clustered according to the isolation medium. Among the bacterial strains, more than 24 % of the isolates could use n-hexadecane as the sole carbon source for growth. For the first time, the alkane-degrading ability and alkB/alkM were detected in Rhizobium, Rhodobacter, Trichococcus, Micrococcus, Enterococcus, and Bavariicoccus strains, and the alkM gene was detected in Firmicutes strains.

A Novel Bacteriophage Targeting Cronobacter sakazakii Is a Potential Biocontrol Agent in Foods

PubMed Central

Lee, Ju-Hoon; Bai, Jaewoo; Shin, Hakdong; Kim, Yeran; Park, Bookyung; Heu, Sunggi

2015-01-01

Cronobacter sakazakii is an important pathogen that causes high mortality in infants. Due to its occasional antibiotic resistance, a bacteriophage approach might be an alternative effective method for the control of this pathogen. To develop a novel biocontrol agent using bacteriophages, the C. sakazakii-infecting phage CR5 was newly isolated and characterized. Interestingly, this phage exhibited efficient and relatively durable host lysis activity. In addition, a specific gene knockout study and subsequent complementation experiment revealed that this phage infected the host strain using the bacterial flagella. The complete genome sequence analysis of phage CR5 showed that its genome contains 223,989 bp of DNA, including 231 predicted open reading frames (ORFs), and it has a G+C content of 50.06%. The annotated ORFs were classified into six functional groups (structure, packaging, host lysis, DNA manipulation, transcription, and additional functions); no gene was found to be related to virulence or toxin or lysogen formation, but >80% of the predicted ORFs are unknown. In addition, a phage proteomic analysis using SDS-PAGE and matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) revealed that seven phage structural proteins are indeed present, supporting the ORF predictions. To verify the potential of this phage as a biocontrol agent against C. sakazakii, it was added to infant formula milk contaminated with a C. sakazakii clinical isolate or food isolate, revealing complete growth inhibition of the isolates by the addition of phage CR5 when the multiplicity of infection (MOI) was 105. PMID:26497465

BACTERIAL CONTAMINATION OF STETHOSCOPES

PubMed Central

Bukharie, Huda A.; Al-Zahrani, Hussain; Rubaish, Abdullah M.; Abdulmohsen, Mohammed F.

2004-01-01

Background: A stethoscope, an essential tool of the medical profession, can become a source of nosocomial infection. Objective: To determine the frequency of bacterial contamination of stethoscopes as well as the practices used for cleaning them. Methods: Cultures were taken from 100 stethoscopes used by different medical personnel in different hospital services. The stethoscopes were collected while the staff filled in a questionnaire. Results: Thirty (30%) out of the 100 stethoscopes surveyed were contaminated with microorganisms. The majority of organisms isolated were gram-positive bacteria (gram positive bacilli 12%, gram-negative bacteria 9%, gram-positive cocci 9%). None of the stethoscopes grew methicillin-resistant staphylococcus aureus. Overall, 21% of the health personnel cleaned their stethoscopes daily, 47% weekly, and 32% yearly. None of the health care workers cleaned their stethoscopes after every patient. Nurses cleaned their stethoscopes more often than physicians and medical students. Conclusion: Stethoscopes may be important in the spread of infectious agents. Their regular disinfection after use on each patient should be considered, particularly in such areas of the hospital, as the critical care units, and oncology units which house many patients with antibiotic-resistant organisms. PMID:23012043

Identification of non-Listeria spp. bacterial isolates yielding a β-D-glucosidase-positive phenotype on Agar Listeria according to Ottaviani and Agosti (ALOA).

PubMed

Angelidis, Apostolos S; Kalamaki, Mary S; Georgiadou, Sofia S

2015-01-16

Agar Listeria according to Ottaviani and Agosti (ALOA) is the mandatory medium used for the detection and enumeration of Listeria monocytogenes in foods according to the official International Organization for Standardization (ISO) methods. On ALOA, Listeria spp. appear as bluish-green colonies due to the production of β-D-glucosidase, an enzyme that cleaves 5-bromo-4-chloro-3-indolyl-β-D-glucopyranoside, a chromogenic substrate included in the formulation of the medium. The present work reports on bacterial isolates (n=64) from ready-to-eat soft cheeses, which are able to grow on ALOA, forming bluish-green colonies and therefore phenotypically resemble Listeria spp. All isolates were also capable of growing on the selective media PALCAM and RAPID L'mono. The isolates were characterised with biochemical tests including those specified in the ISO standards for the confirmation of Listeria spp. and identified via partial sequencing of their 16S rRNA gene. According to sequencing results the isolates represented 12 different bacterial species or species-groups belonging to seven different genera: Bacillus spp. (B. circulans, B. clausii, B. licheniformis and B. oleronius), Cellulosimicrobium spp. (C. funkei), Enterococcus spp. (E. faecalis, E. faecium/durans), Kocuria spp. (K. kristinae), Marinilactibacillus spp. (M. psychrotolerans), Rothia spp. (R. terrae) and Staphylococcus spp. (S. sciuri and S. saprophyticus subsp. saprophyticus/xylosus). Cellulosimicrobium spp. have never been previously isolated from foods. These results significantly extend the list of bacteria previously known as capable of growing on ALOA as bluish-green colonies and suggest that there may be room for further improvement in the medium's inhibitory properties towards non-Listeria spp., Gram-positive bacteria present in foods. Copyright © 2014 Elsevier B.V. All rights reserved.

Identification of Bacterial Species in Kuwaiti Waters Through DNA Sequencing

NASA Astrophysics Data System (ADS)

Chen, K.

2017-01-01

With an objective of identifying the bacterial diversity associated with ecosystem of various Kuwaiti Seas, bacteria were cultured and isolated from 3 water samples. Due to the difficulties for cultured and isolated fecal coliforms on the selective agar plates, bacterial isolates from marine agar plates were selected for molecular identification. 16S rRNA genes were successfully amplified from the genome of the selected isolates using Universal Eubacterial 16S rRNA primers. The resulted amplification products were subjected to automated DNA sequencing. Partial 16S rDNA sequences obtained were compared directly with sequences in the NCBI database using BLAST as well as with the sequences available with Ribosomal Database Project (RDP).

The role of respiratory viruses in the etiology of bacterial pneumonia

PubMed Central

Lee, Kyu Han; Gordon, Aubree; Foxman, Betsy

2016-01-01

Pneumonia is the leading cause of death among children less than 5 years old worldwide. A wide range of viral, bacterial and fungal agents can cause pneumonia: although viruses are the most common etiologic agent, the severity of clinical symptoms associated with bacterial pneumonia and increasing antibiotic resistance makes bacterial pneumonia a major public health concern. Bacterial pneumonia can follow upper respiratory viral infection and complicate lower respiratory viral infection. Secondary bacterial pneumonia is a major cause of influenza-related deaths. In this review, we evaluate the following hypotheses: (i) respiratory viruses influence the etiology of pneumonia by altering bacterial community structure in the upper respiratory tract (URT) and (ii) respiratory viruses promote or inhibit colonization of the lower respiratory tract (LRT) by certain bacterial species residing in the URT. We conducted a systematic review of the literature to examine temporal associations between respiratory viruses and bacteria and a targeted review to identify potential mechanisms of interactions. We conclude that viruses both alter the bacterial community in the URT and promote bacterial colonization of the LRT. However, it is uncertain whether changes in the URT bacterial community play a substantial role in pneumonia etiology. The exception is Streptococcus pneumoniae where a strong link between viral co-infection, increased carriage and pneumococcal pneumonia has been established. PMID:26884414

Optoacoustic sensing of ocular bacterial antigen using targeted gold nanorods

NASA Astrophysics Data System (ADS)

Maswadi, Saher; Page, Leland; Woodward, Lee; Glickman, Randolph D.; Barsalou, Norman

2008-02-01

Bacterial contamination can be detected using a minimally invasive optical method, based on laser-induced optoacoustic spectroscopy, to probe for specific antigens associated with a specific infectious agent. As a model system, we have used a surface antigen (Ag), isolated from Chlamydia trachomatis, and a complementary antibody (Ab). A preparation of 0.2 mg/ml of monoclonal Ab specific to the C. trachomatis surface Ag was conjugated to gold nanorods using standard commercial reagents, in order to produce a targeted contrast agent with a strong optoacoustic signal. The C. trachomatis Ag was absorbed in standard plastic microwells, and the binding of the complementary Ab-nanorod conjugate was tested in an immunoaffinity assay. Optoacoustic signals were elicited from the bound nanorods, using an optical parametric oscillator (OPO) laser system as the optical pump. The wavelength tuneability of the OPO optimized the spectroscopic measurement by exciting the nanorods at their optical absorption maxima. Optoacoustic responses were measured in the microwells using a probe beam deflection technique. Immunoaffinity assays were performed on several dilutions of purified C. trachomatis antigen ranging from 50 μg/ml to 1 pg/ml, in order to determine the detection limit for the optoacoustic-based assay. Only when the antigen was present, and the complementary Ab-NR reagent was introduced into the microwell, was an enhanced optoacoustic signal obtained, which indicated specific binding of the Ab-NR complex. The limit of detection with the current system design is between 1 and 5 pg/ml of bacterial Ag.

Bacterial Etiology and Antibiotic Resistance Profile of Community-Acquired Urinary Tract Infections in a Cameroonian City.

PubMed

Nzalie, Rolf Nyah-Tuku; Gonsu, Hortense Kamga; Koulla-Shiro, Sinata

2016-01-01

Introduction. Community-acquired urinary tract infections (CAUTIs) are usually treated empirically. Geographical variations in etiologic agents and their antibiotic sensitivity patterns are common. Knowledge of antibiotic resistance trends is important for improving evidence-based recommendations for empirical treatment of UTIs. Our aim was to determine the major bacterial etiologies of CAUTIs and their antibiotic resistance patterns in a cosmopolitan area of Cameroon for comparison with prescription practices of local physicians. Methods. We performed a cross-sectional descriptive study at two main hospitals in Yaoundé, collecting a clean-catch mid-stream urine sample from 92 patients having a clinical diagnosis of UTI. The empirical antibiotherapy was noted, and identification of bacterial species was done on CLED agar; antibiotic susceptibility testing was performed using the Kirby-Bauer disc diffusion method. Results. A total of 55 patients had samples positive for a UTI. Ciprofloxacin and amoxicillin/clavulanic acid were the most empirically prescribed antibiotics (30.9% and 23.6%, resp.); bacterial isolates showed high prevalence of resistance to both compounds. Escherichia coli (50.9%) was the most common pathogen, followed by Klebsiella pneumoniae (16.4%). Prevalence of resistance for ciprofloxacin was higher compared to newer quinolones. Conclusions. E. coli and K. pneumoniae were the predominant bacterial etiologies; the prevalence of resistance to commonly prescribed antibiotics was high.

[Epidemio-clinical aspects of adult acute bacterial pneumonia at Yalgado Ouédraogo University Health Center].