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Sample records for gram-positive cocci isolated

  1. Gram-Positive Anaerobic Cocci

    PubMed Central

    Murdoch, D. A.

    1998-01-01

    Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms defined by their morphological appearance and their inability to grow in the presence of oxygen; most clinical isolates are identified to species in the genus Peptostreptococcus. GPAC are part of the normal flora of all mucocutaneous surfaces and are often isolated from infections such as deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections. They have been little studied for several reasons, which include an inadequate classification, difficulties with laboratory identification, and the mixed nature of the infections from which they are usually isolated. Nucleic acid studies indicate that the classification is in need of radical revision at the genus level. Several species of Peptostreptococcus have recently been described, but others still await formal recognition. Identification has been based on carbohydrate fermentation tests, but most GPAC are asaccharolytic and use the products of protein degradation for their metabolism; the introduction of commercially available preformed enzyme kits affords a physiologically more appropriate method of identification, which is simple and relatively rapid and can be used in routine diagnostic laboratories. Recent reports have documented the isolation in pure culture of several species, notably Peptostreptococcus magnus, from serious infections. Studies of P. magnus have elucidated several virulence factors which correlate with the site of infection, and reveal some similarities to Staphylococcus aureus. P. micros is a strongly proteolytic species; it is increasingly recognized as an important pathogen in intraoral infections, particularly periodontitis, and mixed anaerobic deep-organ abscesses. Comparison of antibiotic susceptibility patterns reveals major differences between species. Penicillins are the antibiotics of choice, although some strains of P. anaerobius show broad-spectrum β-lactam resistance. PMID:9457430

  2. Vancomycin-resistant gram-positive cocci isolated from the saliva of wild songbirds.

    PubMed

    Ishihara, Shingo; Bitner, Jessica J; Farley, Greg H; Gillock, Eric T

    2013-04-01

    We analyzed highly vancomycin-resistant Gram-positive bacteria isolated from the saliva of migratory songbirds captured, sampled, and released from a bird-banding station in western Kansas. Individual bacterial isolates were identified by partial 16S rRNA sequencing. Most of the bacteria in this study were shown to be Staphylococcus succinus with the majority being isolated from the American Robin. Some of these bacteria were shown to carry vanA, vanB, and vanC vancomycin-resistance genes and have the ability to form biofilms. One of the van gene-carrying isolates is also coagulase positive, which is normally considered a virulence factor. Other organisms isolated included Staphylococcus saprophyticus as well as Enterococcus gallinarum. Given the wide range of the American Robin and ease of horizontal gene transfer between Gram-positive cocci, we postulate that these organisms could serve as a reservoir of vancomycin-resistance genes capable of transferring to human pathogens.

  3. Changes of the Quinolones Resistance to Gram-positive Cocci Isolated during the Past 8 Years in the First Bethune Hospital

    NASA Astrophysics Data System (ADS)

    Xu, Jiancheng; Chen, Qihui; Yao, Hanxin; Zhou, Qi

    This study was to investigate the quinolones resistance to gram-positive cocci isolated in the First Bethune Hospital during the past 8 years. Disk diffusion test was used to study the antimicrobial resistance. The data were analyzed by WHONET 5 software according to Clinical and Laboratory Standards Institute (CLSI). The rates of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant coagulase-negative Staphylococci (MRCNS) were 50.8%∼83.3% and 79.4%∼81.5%during the past 8 years, respectively. In recent 8 years, the quinolones resistance to gram-positive cocci had increased. Monitoring of the quinolones resistance to gram-positive cocci should be strengthened. The change of the antimicrobial resistance should be investigated in order to guide rational drug usage in the clinic and prevent bacterial strain of drug resistance from being transmitted.

  4. Vancomycin tolerance in Gram-positive cocci.

    PubMed

    Moscoso, Miriam; Domenech, Mirian; García, Ernesto

    2011-12-01

    Vancomycin, a glycopeptide antimicrobial agent, represents the last line of defence against a wide range of multi-resistant Gram-positive pathogens such as enterococci, staphylococci and streptococci. However, vancomycin-resistant enterococci and staphylococci, along with vancomycin-tolerant clinical isolates, are compromising the therapeutic efficacy of vancomycin. It is conceivable that tolerance may emerge during prolonged vancomycin use. It has not been until recently, however, that the molecular basis of this tolerance began to be understood. Superoxide anions might be involved in the bactericidal activity of vancomycin in enterococci, and recent evidence suggests that the stringent response is partly responsible for vancomycin tolerance in Enterococcus faecalis. The mechanism of vancomycin tolerance in Staphylococcus aureus and Streptococcus pneumoniae is sometimes associated with a reduction of autolysin activity. Vancomycin tolerance in S. aureus and S. pneumoniae also appears to be somehow related with the two-component regulatory systems linked to cell envelope stress, although the precise molecular regulatory pathways remain poorly defined. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  5. Evaluation of Antibiotic Susceptibility of Gram-Positive Anaerobic Cocci Isolated from Cancer Patients of the N. N. Blokhin Russian Cancer Research Center.

    PubMed

    Shilnikova, Irina I; Dmitrieva, Natalia V

    2015-01-01

    In total, 81 nonduplicate gram-positive anaerobic cocci (GPAC) were involved in this study. The GPAC were isolated from samples collected from cancer patients between 2004 and 2014. Species identification was carried out by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The majority of isolates were identified as Finegoldia magna (47%) and Peptoniphilus harei (28%). The susceptibility of six species of GPAC was determined for eight antibiotics according to E-test methodology. Furthermore, all isolates were susceptible to imipenem, vancomycin, and linezolid. Susceptibility to penicillin G, amoxicillin/clavulanate, metronidazole, ciprofloxacin, and levofloxacin varied for different species. One Finegoldia magna isolate was multidrug-resistant (i.e., parallel resistance to five antimicrobial agents, including metronidazole, was observed). Two Parvimonas micra isolates were highly resistant to metronidazole (MIC 256 μg/mL) but were sensitive to other tested antibiotics.

  6. Evaluation of Antibiotic Susceptibility of Gram-Positive Anaerobic Cocci Isolated from Cancer Patients of the N. N. Blokhin Russian Cancer Research Center

    PubMed Central

    Shilnikova, Irina I.; Dmitrieva, Natalia V.

    2015-01-01

    In total, 81 nonduplicate gram-positive anaerobic cocci (GPAC) were involved in this study. The GPAC were isolated from samples collected from cancer patients between 2004 and 2014. Species identification was carried out by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The majority of isolates were identified as Finegoldia magna (47%) and Peptoniphilus harei (28%). The susceptibility of six species of GPAC was determined for eight antibiotics according to E-test methodology. Furthermore, all isolates were susceptible to imipenem, vancomycin, and linezolid. Susceptibility to penicillin G, amoxicillin/clavulanate, metronidazole, ciprofloxacin, and levofloxacin varied for different species. One Finegoldia magna isolate was multidrug-resistant (i.e., parallel resistance to five antimicrobial agents, including metronidazole, was observed). Two Parvimonas micra isolates were highly resistant to metronidazole (MIC 256 μg/mL) but were sensitive to other tested antibiotics. PMID:26798518

  7. Evaluation of five selective media for isolation of catalase-negative gram-positive cocci from bulk tank milk.

    PubMed

    Sawant, Ashish A; Pillai, Shreekumar R; Jayarao, Bhushan M

    2002-05-01

    Five selective media including Edwards modified medium, Edwards modified medium supplemented with colistin sulfate (5 mg/L) and oxolinic acid (2.5 mg/L), Streptococcus selective medium, Streptosel agar, and thallium-crystal violet-toxin-ferric citrate medium were evaluated for the isolation of streptococci and streptococci-like organisms from raw milk. The sensitivity and specificity of these selective media for streptococci and streptococci-like organisms were determined by using American Type Culture Collection reference strains. Under experimental conditions Edwards modified medium with colistin sulfate (5 mg/L) and oxolinic acid (2.5 mg/L) showed the highest sensitivity (100%) and specificity (100%) for streptococci and streptococci-like organisms followed by thallium-crystal violettoxin-ferric citrate medium, Edwards modified medium, Streptococcus selective medium, and Streptosel agar. Edwards modified medium supplemented with colistin sulfate (5 mg/L) and oxolinic acid (2.5 mg/L) allowed growth of all streptococci and streptococci-like organisms, while inhibiting growth of the staphylococci and gram-negative reference strains. Bulk tank milk samples from 114 dairy herds were spiral plated onto Edwards modified medium with colistin sulfate (5 mg/L) and oxolinic acid (2.5 mg/L). A total of 344 isolates (at least three isolates from each sample) were randomly selected and identified to their species. This medium permitted growth of 328 streptococci and streptococci-like organisms belonging to genera Aerococcus, Enterococcus, Gemella, Lactococcus, Streptococcus, and Vagococcus. When Edwards modified medium supplemented with colistin sulfate (5 mg/L) and oxolinic acid (2.5 mg/L) was evaluated using bulk tank milk samples, the sensitivity and specificity of this medium for streptococci and streptococci-like organisms were observed to be 100 and 87.5%, respectively. The positive predictive value for streptococci and streptococci-like organisms was observed to be 99

  8. Gram-positive, catalase-positive cocci from dry cured Iberian ham and their enterotoxigenic potential.

    PubMed Central

    Rodríguez, M; Núñez, F; Córdoba, J J; Bermúdez, E; Asensio, M A

    1996-01-01

    Iberian ham is an uncooked, cured meat product ripened under natural uncontrolled conditions for 18 to 24 months. Gram-positive, catalase-positive cocci are the main microbial population in Iberian ham for most of the ripening time. Since some of these organisms are able to produce enterotoxins, adequate characterization and toxicological study are needed. For this, 1,327 gram-positive, catalase-positive cocci, isolated from Iberian hams at different stages and locations, were characterized by physiological and biochemical tests. Selected isolates were further characterized by guanine-cytosine (G+C) content and restriction enzyme analysis of genes coding for 16S rRNA. The toxigenic potential of these organisms was tested with specific DNA gene probes for staphylococcal enterotoxins A, B, C, and D and confirmed by semiquantitative sandwich enzyme immunoassay. The majority of the isolates were identified as Staphylococcus spp. and Micrococcus spp. Non-identified gram-positive, catalase-positive cocci which were moderately halophilic and showed a 42 to 52% G+C content were detected. A great variety of staphylococcal strains were found within the different species at any sampling time. Two strains of Staphylococcus xylosus, one Staphylococcus cohnii strain, and four of the non-identified organisms with 42 to 52% G+C contents hybridized with some of the DNA probes for C and D staphylococcal enterotoxin genes. S. xylosus hybridizing with C-enterotoxin probe reacted with both C and D enterotoxins in the immunological test. In addition, enterotoxin D was confirmed in the nonidentified strains. Some toxigenic organisms were isolated from the final product, posing a health hazard for the consumer. PMID:8787389

  9. Prevalence of multidrug resistant Gram-positive cocci in a Chinese hospital over an 8-year period.

    PubMed

    Zhang, Ruiqin; Wang, Fengzhi; Kang, Jianbang; Wang, Xinchun; Yin, Donghong; Dang, Wen; Duan, Jinju

    2015-01-01

    Gram-positive cocci are common causes of bloodstream and nosocomial infections, and their multi-drug resistance is an increasingly serious problem. The present study aimed to assess the prevalence of multi-drug-resistant Gram-positive cocci in a Chinese population. In this retrospective study, data about Gram-positive cocci from in-patients (January 2006 and December 2013) at the Second Hospital of Shanxi Medical University, Taiyuan, China, were reviewed. Antimicrobial susceptibility profile of the isolated Gram-positive cocci was evaluated using the disk diffusion method. Antibiotic resistance was determined according to the Clinical and Laboratory Standards Institute 2009 guidelines. The prevalence of drug resistance was determined, as well as correlation coefficients for various drugs between the resistance rate and year of sample collection. A total of 7789 Gram-positive cocci isolates were found, including 2576 (33%) coagulase-negative Staphylococci, 1477 (19%) Staphylococci aureus, 1343 (17%) Enterococcus faecalis, and 1139 (15%) Enterococcus faecium. The proportions of methicillin-resistant Staphylococci aureus (MRSA) and methicillin-resistant Staphylococci (MRS) were 31.5% (465/1477) and 61.6% (1587/2576), respectively. Among all isolates, MRS had much higher drug resistance rate than methicillin-sensitive Staphylococci (P<0.05). E. faecalis had a higher multi-drug resistance rate than E. faecium (P<0.01). Interestingly, MRSA resistance rates declined over the years, showing a negative correlation coefficient for all drugs, with significance for levofloxacin, azithromycin, erythromycin, and clindamycin (P<0.05), but not sulphamethoxazole/trimethoprim (P=0.057) and gentamicin (P=0.186). These results indicated that Staphylococci were the predominant Gram-positive cocci isolated. There was a trend of decreasing MRSA in the population studied.

  10. Prevalence of multidrug resistant Gram-positive cocci in a Chinese hospital over an 8-year period

    PubMed Central

    Zhang, Ruiqin; Wang, Fengzhi; Kang, Jianbang; Wang, Xinchun; Yin, Donghong; Dang, Wen; Duan, Jinju

    2015-01-01

    Gram-positive cocci are common causes of bloodstream and nosocomial infections, and their multi-drug resistance is an increasingly serious problem. The present study aimed to assess the prevalence of multi-drug-resistant Gram-positive cocci in a Chinese population. In this retrospective study, data about Gram-positive cocci from in-patients (January 2006 and December 2013) at the Second Hospital of Shanxi Medical University, Taiyuan, China, were reviewed. Antimicrobial susceptibility profile of the isolated Gram-positive cocci was evaluated using the disk diffusion method. Antibiotic resistance was determined according to the Clinical and Laboratory Standards Institute 2009 guidelines. The prevalence of drug resistance was determined, as well as correlation coefficients for various drugs between the resistance rate and year of sample collection. A total of 7789 Gram-positive cocci isolates were found, including 2576 (33%) coagulase-negative Staphylococci, 1477 (19%) Staphylococci aureus, 1343 (17%) Enterococcus faecalis, and 1139 (15%) Enterococcus faecium. The proportions of methicillin-resistant Staphylococci aureus (MRSA) and methicillin-resistant Staphylococci (MRS) were 31.5% (465/1477) and 61.6% (1587/2576), respectively. Among all isolates, MRS had much higher drug resistance rate than methicillin-sensitive Staphylococci (P<0.05). E. faecalis had a higher multi-drug resistance rate than E. faecium (P<0.01). Interestingly, MRSA resistance rates declined over the years, showing a negative correlation coefficient for all drugs, with significance for levofloxacin, azithromycin, erythromycin, and clindamycin (P<0.05), but not sulphamethoxazole/trimethoprim (P=0.057) and gentamicin (P=0.186). These results indicated that Staphylococci were the predominant Gram-positive cocci isolated. There was a trend of decreasing MRSA in the population studied. PMID:26309609

  11. Frequency of inducible clindamycin resistance among gram-positive cocci in a tertiary hospital, Tehran, Iran

    PubMed Central

    Saffar, Hiva; Rajabiani, Afsaneh; Abdollahi, Alireza; Habibi, Shirin; Baseri, Zohreh

    2016-01-01

    Background and Objectives: Accurate designation of antimicrobial susceptibility pattern of the infecting microorganisms is an important crucial factor in making appropriate therapeutic decisions. Macrolide, lincosamide and streptogramin B antibiotics are in a family, reserved as an alternative approach in treatment of resistant Gram positive cocci. Amongst them, clindamycin has been considered as the preferred agent due to its excellent pharmacokinetic properties. The inducible resistance to clindamycin in Gram positive staphylococci and streptococci cannot be recognized by routine broth or agar based susceptibility tests and D-zone testing is necessary. This study is conducted to evaluate the frequency of inducible clindamycin resistance in Gram positive cocci. Materials and Methods: Using traditional culture methods, 487 isolates of staphylococcus and β-hemolytic streptococcus were evaluated. If they were resistant to erythromycin and sensitive to clindamycin in primary antibiotic susceptibility testing by Kirby-Bauer method, they were subjected to D-zone testing to detect possible inducible clindamycin resistance. Results: Thirty three out of 172 isolates of Staphylococcus aureus and 50 out of 277 isolates of coagulase-negative staphylococci (CoNS) were subjected for D-zone testing. Among them 13/33 and 28/50 showed inducible clindamycin resistance, respectively. There was no significant difference in inducible clindamycin resistance regarding to methicillin susceptibility pattern. Positive D-test was observed in 17.39 and 13.33% of Group B streptococci and Streptococcus spp., respectively. Conclusion: Considerable number of isolates showed inducible clindamycin resistance in our study which falsely would be reported susceptible if D-zone testing was not performed. Thus, performing D-Zone testing is necessary to avoid misleading results which may cause treatment failure. PMID:28210463

  12. Linezolid activity against clinical Gram-positive cocci with advanced antimicrobial drug resistance in Iran.

    PubMed

    Houri, Hamidreza; Kazemian, Hossein; Sedigh Ebrahim-Saraie, Hadi; Taji, Asieh; Tayebi, Zahra; Heidari, Hamid

    2017-09-01

    The aim of the study was to investigate the linezolid activity against clinical Gram-positive cocci with advanced antimicrobial drug resistance. A collection of methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant enterococci (VRE), penicillin non-susceptible Streptococcus pneumoniae (PNSP), and group B streptococci (GBS) were isolated from various clinical samples. Antimicrobial susceptibility tests were done using standard methods Subsequently, we investigated linezolid antibacterial activities, the first approved oxazolidinone against isolates by the standard broth microdilution method. According to our results, MRSA and PNSP isolates were multidrug resistant, and almost half of the VRE isolates were high level gentamicin resistant (HLGR). Furthermore, resistance to linezolid was not seen among the isolates. The MIC90 values for MRSA, VRE, PNSP and GBS isolates were 4μg/ml, 2μg/ml, 1μg/ml, and 0.5μg/ml, respectively. Only 6.25% of vancomycin resistant enterococci showed intermediate susceptibility to this antibiotic. These findings indicate that linezolid has an excellent activity against clinical drug resistant Gram-positive isolates in Iran. Constant monitoring and surveillance of linezolid MIC distribution allows the researchers to assess and detect gradual upward MIC drifts. Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  13. Antibacterial activity of citreamicin-alpha (LL-E 19085 alpha) against gram-positive cocci.

    PubMed

    Qadri, S M; Saldin, H; Ueno, Y; al-Ballaa, S R

    1992-01-01

    In vitro antibacterial activity of 429 clinical isolates of gram-positive cocci was tested against citreamicin-alpha (LL-E 19085-alpha) by the agar dilution method. The microorganisms consisted of 313 isolates of staphylococci and 116 strains of streptococci. In vitro activity of citreamicin-alpha was compared with ampicillin, augmentin, cephalothin, erythromycin and vancomycin. MICs of citreamicin-alpha for staphylococci ranged between 0.12-4.0 micrograms/ml and 0.03-0.12 micrograms/ml for Streptococcus pyogenes. Enterococci, however, were relatively more resistant, requiring 2.0 micrograms/ml of this drug to inhibit 64% of the 62 isolates tested. In vitro activity of this antibacterial agent was far superior to that of ampicillin, augmentin, cephalothin and erythromycin, but equal to or slightly inferior to that of vancomycin.

  14. Comparative In Vitro Activities of Ciprofloxacin, Gemifloxacin, Grepafloxacin, Moxifloxacin, Ofloxacin, Sparfloxacin, Trovafloxacin, and Other Antimicrobial Agents against Bloodstream Isolates of Gram-Positive Cocci

    PubMed Central

    Hardy, Dwight; Amsterdam, Daniel; Mandell, Lionel A.; Rotstein, Coleman

    2000-01-01

    The in vitro activity of gemifloxacin against 316 bloodstream isolates of staphylococci, pneumococci, and enterococci was compared with the activities of six fluoroquinolones and three other antimicrobial agents. Of the antimicrobial agents tested, gemifloxacin was the most potent against penicillin-intermediate and -resistant pneumococci, methicillin-susceptible and -resistant Staphylococcus epidermidis isolates, and coagulase-negative staphylococci. PMID:10681365

  15. Recovery of vancomycin-resistant gram-positive cocci from pediatric liver transplant recipients.

    PubMed Central

    Green, M; Barbadora, K; Michaels, M

    1991-01-01

    Between November 1988 and October 1989, 49 first-time pediatric liver transplant recipients at the Children's Hospital of Pittsburgh were prospectively monitored for the presence of stool colonization and the development of disease caused by vancomycin-resistant gram-positive cocci (VRGPC). Quantitative stool culturing was done on a weekly basis, and cultures were planted onto a selective medium for VRGPC. Isolates for which the MIC was greater than or equal to 8 were considered resistant to vancomycin. Patients were monitored clinically for the development of infection, and their charts were systematically reviewed for the use of antibiotics. Eighty-six isolates were recovered from 36 of the 49 patients. Enterococcal species were isolated from 31 patients and included Enterococcus gallinarum (n = 28), E. casseliflavus (n = 14), E. faecium (n = 9), E. faecalis (n = 2), E. mundtii (n = 2), and E. durans (n = 1). Stool colonization with vancomycin-resistant enterococci was noted to increase steadily during the first month after transplantation. Only 9 of 31 patients demonstrated clearance of these organisms in serial repeat cultures. Additional isolates of VRGPC included Lactobacillus confusus (n = 13), Lactobacillus spp. (n = 12), and Pediococcus pentosaceus (n = 4). Infection due to VRGPC developed in three patients: a urinary tract infection in two and peritonitis in one. E. faecium was the pathogen in each of these cases. The ranges of MICs of vancomycin were 8 to 32 micrograms/ml for all enterococcal isolates and greater than 128 micrograms/ml for Lactobacillus and Pediococcus isolates. All Lactobacillus and Pediococcus isolates were resistant to teicoplanin, although they were susceptible to daptomycin. All other isolates were susceptible to both teicoplanin and daptomycin. This study demonstrates that stool colonization with VRGPC may be a common and early finding among pediatric liver transplant recipients. However, infection appears to be uncommon. PMID

  16. Antimicrobial activity of fusidic acid and disk diffusion susceptibility testing criteria for gram-positive cocci.

    PubMed

    Toma, E; Barriault, D

    1995-07-01

    The in vitro activity of fusidic acid was assessed and was compared with those of cloxacillin, cefamandole, vancomycin, teicoplanin, ofloxacin, ciprofloxacin, pefloxacin, and fleroxacin against 500 gram-positive cocci: 151 Staphylococcus aureus, 197 coagulase-negative staphylococci, and 152 Enterococcus faecalis strains. All clinical isolates were concomitantly tested by disk diffusion and agar dilution procedures as outlined by the National Committee for Clinical Laboratory Standards. The results with fusidic acid were further analyzed by regression line and error rate-bounded methods. With control American Type Culture Collection organisms, the values were within the limits of the National Committee for Clinical Laboratory Standards or published limits. The incidence of resistance to fusidic acid was 0.7% for S. aureus, 2.5% for coagulase-negative staphylococci, and 99.3% for E. faecalis. The correlation coefficient between the results of disk diffusion and agar dilution tests with fusidic acid was 0.90. Current interpretive criteria for susceptibility to fusidic acid (i.e., MIC of < 2 micrograms/ml and inhibitory zone of 20 mm) gave 1% false susceptibility (all strains being E. faecalis). This error rate is practically eliminated if a zone diameter of 21 mm is considered the breakpoint for susceptibility.

  17. Recovery of Gram-Positive Cocci and Candida albicans from Peroxygen/Silver-Based Disinfectants.

    PubMed

    Eissa, Mostafa E; Nouby, Ahmed S

    2016-01-01

    Neutralization method evaluation is an important first step in a disinfectant validation study program. It is also crucial in assessment of the efficiency of microbial recovery media in the presence of a residual biocidal agent. In the present study, four commercially available peroxygen/silver-based disinfectant formulae--intended to be used in a pharmaceutical facility sanitization program--were tested at two dilutions against three Gram-positive cocci and one yeast; Staphylococcus aureus (ATCC 6538), Kucoria rhizophila (ATCC 9341) and Candida albicans (ATCC 10231) and Staphylococcus capitis as an environmental monitoring (EM) isolate sample (identified by miniaturized biochemical identification system). Disinfectants preparation, dilutions and the test procedure were carried on in laboratory under conditions simulating the working environment of 20-25 degrees C and RH% 40-60. In-house made neutralizing broth was mixed with biocidal agents to make two dilutions of each disinfectant forming Peroxygen: neutralizing broth ratios of 1:10 and 1:100 (v/v). Three populations were established and two comparison ratio groups were examined, namely neutralizer efficacy and neutralizer toxicity. Two acceptance criteria were tested. One criterion showed higher rate of neutralization success than the other. S. aureus showed the highest rate of successful microbial recovery from neutralization process. The Disinfectant (Bixco) was exceptionally neutralized at all dilutions with all microorganisms. In conclusion, in-house made neutralizing broth effectively neutralized all disinfectants with all the tested microorganisms at 1:100 (v/v); thus, it can be used in sanitizer validation studies and EM media.

  18. Agreement Between Deoxyribonucleic Acid Base Composition and Taxometric Classification of Gram-Positive Cocci1

    PubMed Central

    Silvestri, L. G.; Hill, L. R.

    1965-01-01

    Silvestri, L. G. (Università Statale, Milan, Italy), and L. R. Hill. Agreement between deoxyribonucleic acid base composition and taxometric classification of gram-positive cocci. J. Bacteriol. 90:136–140. 1965.—It had been previously proposed, from taxometric analyses, that gram-positive, catalase-positive cocci be divided into two subgroups. Thirteen strains, representative of both subgroups, were examined for deoxyribonucleic acid (DNA) base composition, determined from melting temperatures. Per cent GC (guanine + cytosine/total bases) values fell into two groups: 30.8 to 36.5% GC and 69 to 75% GC. Strains with low per cent GC values belonged to the Staphylococcus aureus–S. saprophyticus–S. lactis taxometric subgroups, and those with high per cent GC values belonged to the S. roseus–S. afermentans subgroup. The hypothetical nature of any classification is emphasized, and, in the present work, the hypothesis derived from taxometric analyses of division into two subgroups is confirmed by the study of DNA base ratios. The two subgroups correspond, respectively, to the genera Staphylococcus and Micrococcus. PMID:16562008

  19. Rapid identification and antimicrobial susceptibility profiling of Gram-positive cocci in blood cultures with the Vitek 2 system.

    PubMed

    Lupetti, A; Barnini, S; Castagna, B; Capria, A-L; Nibbering, P H

    2010-01-01

    Rapid identification and antimicrobial susceptibility profiling of the bacteria in blood cultures can result in clinical and financial benefits. Addition of saponin to the fluid from blood culture bottles promotes the recovery of the bacteria and thus may shorten the turnaround time of the microbiological analyses. In this study we compared the identification and susceptibility profiles of saponin-treated and untreated (standard method) blood cultures monomicrobial for Gram-positive cocci using Vitek 2. We concordantly identified 49 (89%) of 55 monobacterial cultures using the results with the standard method as reference. Complete categorical agreement between the susceptibility profiles with the new and the standard method was found for 26 (53%) of 49 isolates, while discrepancies were seen for 23 (47%) cultures. E-tests indicated that the new method resulted in a correct susceptibility profile for 8 (35%) of these 23 blood cultures. Therefore, 34 (69%) of 49 cultures showed a concordant/correct susceptibility profile for all antimicrobials with an overall error rate of 2.3%. Thus, addition of saponin to the fluid from blood culture bottles of the Bactec 9240 leads to the rapid (results available >or=12 hours earlier) and reliable identification and susceptibility profiling of Gram-positive cocci in blood cultures with Vitek 2.

  20. Aspects of eukaryotic-like signaling in Gram-positive cocci: a focus on virulence

    PubMed Central

    Burnside, Kellie; Rajagopal, Lakshmi

    2011-01-01

    Living organisms adapt to the dynamic external environment for their survival. Environmental adaptation in prokaryotes is thought to be primarily accomplished by signaling events mediated by two-component systems, consisting of histidine kinases and response regulators. However, eukaryotic-like serine/threonine kinases (STKs) have recently been described to regulate growth, antibiotic resistance and virulence of pathogenic bacteria. This article summarizes the role of STKs and their cognate phosphatases (STPs) in Gram-positive cocci that cause invasive infections in humans. Given that a large number of inhibitors to eukaryotic STKs are approved for use in humans, understanding how serine/threonine phosphorylation regulates virulence and antibiotic resistance will be beneficial for the development of novel therapeutic strategies against bacterial infections. PMID:21797690

  1. Effect of spiramycin on adhesiveness and phagocytosis of gram-positive cocci.

    PubMed

    Desnottes, J F; Diallo, N; Moret, G

    1988-07-01

    Three strains of Staphylococcus aureus, serotype 18, Cowan I and serotype 66438, and different species of streptococci (Streptococcus pyogenes, Str, mutans, Str. sanguis and Str. faecalis) were tested for their adherence to buccal cells (as measured by interference contrast microscopy) and phagocytosis by rat polymorphonuclear leucocytes (PMNs) (as measured by fluorescence microscopy with a vital fluorochrome, acridine orange). Pretreatment of cocci with serial two-fold dilutions of spiramycin (from 1/2 to 1/1024 the MIC), increased the diameter of bacterial cells and decreased the adherence of staphylococci and streptococci to buccal cells. Exposure of streptococci to 1/4 the MIC of spiramycin led to an increase of the phagocytic capacity of PMNs. Pretreatment of PMNs with a therapeutic concentration (2 mg/l) also stimulated the phagocytosis of streptococci. Action of spiramycin on the phagocytosis of staphylococci varied according to the strain tested. Although in-vitro results cannot be directly compared with in-vivo data, it is of interest that spiramycin decreases adherence of different Gram-positive cocci and enhances phagocytic capacity of PMNs.

  2. Evaluation of the VITEK 2 System for Identification and Antimicrobial Susceptibility Testing of Medically Relevant Gram-Positive Cocci

    PubMed Central

    Ligozzi, Marco; Bernini, Cinzia; Bonora, Maria Grazia; de Fatima, Maria; Zuliani, Jessica; Fontana, Roberta

    2002-01-01

    A study was conducted to evaluate the new VITEK 2 system (bioMérieux) for identification and antibiotic susceptibility testing of gram-positive cocci. Clinical isolates of Staphylococcus aureus (n = 100), coagulase-negative staphylococci (CNS) (n = 100), Enterococcus spp. (n = 89), Streptococcus agalactiae (n = 29), and Streptococcus pneumoniae (n = 66) were examined with the ID-GPC identification card and with the AST-P515 (for staphylococci), AST-P516 (for enterococci and S. agalactiae) and AST-P506 (for pneumococci) susceptibility cards. The identification comparison methods were the API Staph for staphylococci and the API 20 Strep for streptococci and enterococci; for antimicrobial susceptibility testing, the agar dilution method according to the procedure of the National Committee for Clinical Laboratory Standards (NCCLS) was used. The VITEK 2 system correctly identified to the species level (only one choice or after simple supplementary tests) 99% of S. aureus, 96.5% of S. agalactiae, 96.9% of S. pneumoniae, 92.7% of Enterococcus faecalis, 91.3% of Staphylococcus haemolyticus, and 88% of Staphylococcus epidermidis but was least able to identify Enterococcus faecium (71.4% correct). More than 90% of gram-positive cocci were identified within 3 h. According to the NCCLS breakpoints, antimicrobial susceptibility testing with the VITEK 2 system gave 96% correct category agreement, 0.82% very major errors, 0.17% major errors, and 2.7% minor errors. Antimicrobial susceptibility testing showed category agreement from 94 to 100% for S. aureus, from 90 to 100% for CNS, from 91 to 100% for enterococci, from 96 to 100% for S. agalactiae, and from 91 to 100% for S. pneumoniae. Microorganism-antibiotic combinations that gave very major errors were CNS-erythromycin, CNS-oxacillin, enterococci-teicoplanin, and enterococci-high-concentration gentamicin. Major errors were observed for CNS-oxacillin and S. agalactiae-tetracycline combinations. In conclusion the results of

  3. Virulence arsenal of the most pathogenic species among the Gram-positive anaerobic cocci, Finegoldia magna.

    PubMed

    Boyanova, Lyudmila; Markovska, Rumyana; Mitov, Ivan

    2016-12-01

    This review focuses on the virulence arsenal of the most pathogenic species among Gram positive anaerobic cocci, Finegoldia magna according to recently published data from 2012 to 2016. Virulence factors like sortase dependent pili and F. magna adhesion factor (FAF) facilitate the start of the infection. Albumin binding protein (PAB) enhances F. magna survival. FAF, subtilisin-like extracellular serine protease (SufA) and superantigen protein L protect the bacteria from factors of innate defense system. SufA, capsule and tissue-destroying enzymes provide a deep penetration or spread of the infections and the protein L is associated with infection severity. Biofilm production results in infection chronification and complicated treatment as well as to persistence of multi-species biofilms. Resistance rates to quinolones (13.0->70%) and clindamycin (0-40.0%) are important, and resistance to penicillins (<4%), chloramphenicol (7.0%) and metronidazole (<7%) has been reported. F. magna should not be overlooked when present in monoinfections or mixed infections in humans.

  4. In-vitro activities of 14-, 15- and 16-membered macrolides against gram-positive cocci.

    PubMed

    Hamilton-Miller, J M

    1992-02-01

    The in-vitro activities of the 14-membered macrolides erythromycin, dirithromycin, roxithromycin, clarithromycin, the 15-membered compound azithromycin and the 16-membered macrolides (16 MM) josamycin, spiramycin and midecamycin acetate (MOM) have been compared against staphylococci, enterococci and streptococci. Results have been analysed separately according to the sensitivity status of the tested strains to erythromycin, namely sensitive (S), inducibly resistant (IR) or constitutively resistant (CR). 14- and 15-membered macrolides were active only against S strains; the order of potency in vitro was clarithromycin = erythromycin greater than azithromycin = roxithromycin greater than dirithromycin. The 16 MM were slightly less active against S strains than were the 14- and 15-membered compounds, and inhibited most IR strains; MOM and josamycin were about twice as potent as spiramycin. IR and S Staphylococcus aureus strains were equally sensitive to 16 MM, while IR strains of coagulase-negative staphylococci were less sensitive than were S strains. All CR strains of S. aureus were resistant to 16 MM, as were most of the other CR strains. However, 5/21 CR coagulase-negative staphylococci and 2/20 CR enterococci tested were sensitive to 16 MM. The seven CR strains showing anomalous sensitivity to the 16 MM (five Staphylococcus haemolyticus and two enterococci) were only 'moderately resistant' to erythromycin (MIC 8-64 mg/L), while all the other CR strains were 'highly resistant' (MIC greater than 128 mg/L). These results indicate that it may be difficult to predict the sensitivity of Gram-positive cocci to 16 MM, and therefore individual sensitivity testing to specific compounds is essential.

  5. Heterogeneity within the gram-positive anaerobic cocci demonstrated by analysis of 16S-23S intergenic ribosomal RNA polymorphisms.

    PubMed

    Hill, K E; Davies, C E; Wilson, M J; Stephens, P; Lewis, M A O; Hall, V; Brazier, J; Thomas, D W

    2002-11-01

    Peptostreptococci are gram-positive, strictly anaerobic bacteria which, although regarded as members of the commensal human microflora, are also frequently isolated from sites of clinical infection. The study of this diverse group of opportunist pathogens has been hindered by an inadequate taxonomy and the lack of a valid identification scheme. Recent re-classification of the Peptostreptococcus family into five distinct genus groups has helped to clarify the situation. However, this has been on the basis of 16S rRNA sequence determinations, which are both time-consuming and expensive. The aim of the present study was to evaluate the use of PCR-amplified ribosomal DNA spacer polymorphisms for the rapid differentiation of the currently recognised taxa within the group of anaerobic gram-positive cocci. A collection comprising 19 reference strains with representatives of each of the 15 species, two close relatives and two of the well-characterised groups, together with 38 test strains was studied. All strains were identified to species group level by phenotypic means. Amplification of the 16S-23S intergenic spacer region (ISR) with universal primers produced distinct banding patterns for all the 19 reference strains and the patterns could be differentiated easily visually. However, of the 38 test strains, less than half could be speciated from ISR analysis alone. Only five groups produced correlating banding patterns for all members tested (Peptoniphilus lacrimalis, P. ivorii, Anaerococcus octavius, Peptostreptococcus anaerobius and Micromonas micros). For other species, either the type strain differed significantly from other species members (e.g., A. hydrogenalis) or there appeared to be considerable intra-species variation (e.g., A. vaginalis). Partial 16S rRNA gene sequences for the 'trisimilis' and 'betaGAL' groups showed that both are most closely related to the Anaerococcus group. This work highlights the heterogeneous nature of a number of Peptostreptococcus

  6. Identification of pili on the surface of Finegoldia magna--a gram-positive anaerobic cocci.

    PubMed

    Murphy, Elizabeth C; Janulczyk, Robert; Karlsson, Christofer; Mörgelin, Matthias; Frick, Inga-Maria

    2014-06-01

    Pili have only been discovered in the major Gram-positive pathogens in the past decade and they have been found to play an important role in colonisation and virulence. Pili have been shown to have many important functions including attachment to host tissues, mediating bacterial aggregation, biofilm formation and binding to proteins in the extracellular matrix. In this study, sortase-dependent pili have been found to be expressed on the surface of Finegoldia magna ALB8. F. magna is a Gram-positive anaerobic coccus that, primarily, is a commensal of the skin and mucous membranes, but has also been isolated from various clinical infection sites and is associated with soft-tissue abscesses, wound infections and bone and prosthetic joint infections. In this study, F. magna ALB8 was found to harbour three sortases at the pilus locus, two of which bear high similarity to class C sortases in Streptococcus pneumoniae. Two putative sortase-dependent pili proteins were found in the locus, with one being identified as the major pilus subunit, Fmp1 (F. magna pilus subunit 1), due to its high similarity to other major pilus proteins in prominent Gram-positive pathogens. The presence of sortase-dependent pili was confirmed experimentally through recombinant production of Fmp1 and production of antiserum. The Fmp1 antiserum was used in Western blot to show the presence of a high molecular weight protein ladder, characteristic of the presence of pili, in trypsin released cell wall surface proteins from F. magna. The presence of sortase-dependent pili was visually confirmed by transmission electron microscopy, which showed the binding of gold labelled anti-Fmp1 to individual pilus proteins along the pilus. Furthermore, pili could also be found to bind and interact with keratinocytes in the epidermal layer of human skin, suggesting an adhesive role for pili on F. magna. Our work represents the first description of pilus structures in F. magna. This discovery further

  7. Accuracy of the VITEK® 2 system for a rapid and direct identification and susceptibility testing of Gramnegative rods and Gram-positive cocci in blood samples.

    PubMed

    Nimer, N A; Al-Saa'da, R J; Abuelaish, O

    2016-06-15

    The performance of the VITEK® 2 system for direct rapid identification and antimicrobial susceptibility testing of the bacteria responsible for blood infections was determined. The isolates studied included 166 Gram-negative rods and 74 Gram-positive cocci from inpatients. Specially treated monomicrobial samples from positive blood culture bottles were directly inoculated into the VITEK 2 system and the results were compared with those from cards inoculated with standardized bacterial suspensions. Compared with the standard method, 95.8% of Gram-negative rods were correctly identified by VITEK 2 and the overall level of agreement between the two methods in susceptibility testing was 92.0%. For Gram-positive bacteria, 89.2% were correctly identified by VITEK 2 and susceptibility testing revealed an overall agreement rate of 91.3%. These results suggest that VITEK 2 cards inoculated with fluids sampled directly from positive blood culture bottles are suitable for speedy identification and susceptibility testing of Gram-negative bacilli and Gram-positive cocci.

  8. Efficacy of direct Gram stain in differentiating staphylococci from streptococci in blood cultures positive for gram-positive cocci.

    PubMed Central

    Agger, W A; Maki, D G

    1978-01-01

    A preponderance of clusters seen on direct Gram stain of blood cultures positive for gram-positive cocci was 98% sensitive and 100% specific for identification of staphylococcal species or of Peptococcus. A preponderance of chains, pairs, or both was 100% sensitive and 98% specific for identifying streptococci. Further presumptive identification of either staphylococci or streptococci based on microscopic morphology was unreliable. The direct Gram stain is highly reliable for differentiating staphylococci from streptococci and should be of considerable value to clinicians selecting initial antimicrobial therapy. PMID:75888

  9. [Resistance to "last resort" antibiotics in Gram-positive cocci: The post-vancomycin era].

    PubMed

    Rincón, Sandra; Panesso, Diana; Díaz, Lorena; Carvajal, Lina P; Reyes, Jinnethe; Munita, José M; Arias, César A

    2014-04-01

    New therapeutic alternatives have been developed in the last years for the treatment of multidrug-resistant Gram-positive infections. Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) are considered a therapeutic challenge due to failures and lack of reliable antimicrobial options. Despite concerns related to the use of vancomycin in the treatment of severe MRSA infections in specific clinical scenarios, there is a paucity of solid clinical evidence that support the use of alternative agents (when compared to vancomycin). Linezolid, daptomycin and tigecycline are antibiotics approved in the last decade and newer cephalosporins (such as ceftaroline and ceftobiprole) and novel glycopeptides (dalvavancin, telavancin and oritavancin) have reached clinical approval or are in the late stages of clinical development. This review focuses on discussing these newer antibiotics used in the "post-vancomycin" era with emphasis on relevant chemical characteristics, spectrum of antimicrobial activity, mechanisms of action and resistance, as well as their clinical utility.

  10. 18 GHz electromagnetic field induces permeability of Gram-positive cocci

    PubMed Central

    Nguyen, The Hong Phong; Shamis, Yury; Croft, Rodney J.; Wood, Andrew; McIntosh, Robert L.; Crawford, Russell J.; Ivanova, Elena P.

    2015-01-01

    The effect of electromagnetic field (EMF) exposures at the microwave (MW) frequency of 18 GHz, on four cocci, Planococcus maritimus KMM 3738, Staphylococcus aureus CIP 65.8T, S. aureus ATCC 25923 and S. epidermidis ATCC 14990T, was investigated. We demonstrate that exposing the bacteria to an EMF induced permeability in the bacterial membranes of all strains studied, as confirmed directly by transmission electron microscopy (TEM), and indirectly via the propidium iodide assay and the uptake of silica nanospheres. The cells remained permeable for at least nine minutes after EMF exposure. It was shown that all strains internalized 23.5 nm nanospheres, whereas the internalization of the 46.3 nm nanospheres differed amongst the bacterial strains (S. epidermidis ATCC 14990T~ 0%; Staphylococcus aureus CIP 65.8T S. aureus ATCC 25923, ~40%; Planococcus maritimus KMM 3738, ~80%). Cell viability experiments indicated that up to 84% of the cells exposed to the EMF remained viable. The morphology of the bacterial cells was not altered, as inferred from the scanning electron micrographs, however traces of leaked cytosolic fluids from the EMF exposed cells could be detected. EMF-induced permeabilization may represent an innovative, alternative cell permeability technique for applications in biomedical engineering, cell drug delivery and gene therapy. PMID:26077933

  11. Cell density--dependent regulation: basic principles and effects on the virulence of Gram-positive cocci.

    PubMed

    Podbielski, Andreas; Kreikemeyer, Bernd

    2004-03-01

    Quorum sensing (QS) regulation appears to be a consequence of interbacterial communication by which bacteria of one or even different species learn about their current population density and react in a defined way to that information. QS-regulation is a three step process: in the first step specific signaling molecules are produced and secreted to the exterior space. In the second step, the molecules accumulate e.g. with growing population density. In the last step, a supra-threshold concentration of the molecules is extra- or intra-cellularly sensed by the bacteria and leads to a cascade of regulatory activities. While Gram-negative bacteria can employ five or more different chemical classes of signaling molecules, Gram-positive cocci predominantly use special oligopeptides for specific signaling. Examples of QS-regulatory effects on virulence factor expression in Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis are given. In these bacteria, QS-regulation appears to be crucial for displaying tissue invasiveness and/or biofilm formation. The high specificity of the initial signal sensing and the importance for expressing special virulence traits make this type of gene expression control a promising target for the development of novel therapeutics. The options for such therapies are critically discussed based on practical experiences with interference in S. aureus QS-regulation.

  12. [Evaluation of rapid genotype assay for the identification of gram-positive cocci from blood cultures and detection of mecA and van genes].

    PubMed

    Gülhan, Barış; Atmaca, Selahattin; Ozekinci, Tuncer; Suay, Adnan

    2011-10-01

    Rapid and accurate identification of bacterial pathogens grown in blood cultures of patients with sepsis is crucial for prompt initiation of appropriate therapy in order to decrease related morbidity and mortality rates. Although current automated blood culture systems led to a significant improvement in bacterial detection time, more rapid identification systems are still needed to optimise the establishment of treatment. Novel genotype technology which is developed for the rapid diagnosis of sepsis, is a molecular genetic assay based on DNA multiplex amplification with biotinylated primers followed by hybridization to membrane bound probes. The aim of this study was to evaluate the performance of "Genotype® BC gram-positive” test for the identification of gram-positive cocci grown in blood cultures and rapid detection of mecA and van genes. This test uses DNA.STRIP® technology which includes a panel of probes for identification of 17 gram-positive bacterial species and is able to determinate the methicillin and vancomycin resistance mediating genes (mecA and vanA, vanB, vanC1, vanC2/C3) simultaneously, in a single test run. A total of 55 positive blood cultures from BACTECTM Plus/F (Becton Dickinson, USA) aerobic and pediatric blood culture vials were included in the study. The isolates which exhibit gram-positive coccus morphology by Gram staining were identified by Genotype ® BC gram-positive test (Hain Life Science, Germany). All of the samples were also identified with the use of Phoenix PMIC/ID Panel (Becton Dickinson, USA) and antibiotic susceptibilities were determined. Of the 55 blood culture isolates, 17 were identified as Staphylococcus epidermidis [all were methicillin-resistant (MR)], 9 were S.aureus (one was MR), 18 were S.hominis (10 were MR), 4 were E.faecalis, 3 were E. faecium (one was vanconycin-resistant), 2 were S.saprophyticus (one was MR), 1 was S.warneri and 1 was S.haemolyticus, by Phoenix automated system. Genotype® BC gram-positive

  13. Identification of Gram-positive cocci by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry: comparison of different preparation methods and implementation of a practical algorithm for routine diagnostics.

    PubMed

    Schulthess, Bettina; Brodner, Katharina; Bloemberg, Guido V; Zbinden, Reinhard; Böttger, Erik C; Hombach, Michael

    2013-06-01

    This study compared three sample preparation methods (direct transfer, the direct transfer-formic acid method with on-target formic acid treatment, and ethanol-formic acid extraction) for the identification of Gram-positive cocci with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A total of 156 Gram-positive cocci representing the clinically most important genera, Aerococcus, Enterococcus, Staphylococcus, and Streptococcus, as well as more rare genera, such as Gemella and Granulicatella, were analyzed using a Bruker MALDI Biotyper. The rate of correct genus-level identifications was approximately 99% for all three sample preparation methods. The species identification rate was significantly higher for the direct transfer-formic acid method and ethanol-formic acid extraction (both 77.6%) than for direct transfer (64.1%). Using direct transfer-formic acid compared to direct transfer, the total time to result was increased by 22.6%, 16.4%, and 8.5% analyzing 12, 48, and 96 samples per run, respectively. In a subsequent prospective study, 1,619 clinical isolates of Gram-positive cocci were analyzed under routine conditions by MALDI-TOF MS, using the direct transfer-formic acid preparation, and by conventional biochemical methods. For 95.6% of the isolates, a congruence between conventional and MALDI-TOF MS identification was observed. Two major limitations were found using MALDI-TOF MS: the differentiation of members of the Streptococcus mitis group and the identification of Streptococcus dysgalactiae. The Bruker MALDI Biotyper system using the direct transfer-formic acid sample preparation method was shown to be a highly reliable tool for the identification of Gram-positive cocci. We here suggest a practical algorithm for the clinical laboratory combining MALDI-TOF MS with phenotypic and molecular methods.

  14. In Vitro Activities of Tedizolid and Linezolid against Gram-Positive Cocci Associated with Acute Bacterial Skin and Skin Structure Infections and Pneumonia.

    PubMed

    Chen, Ko-Hung; Huang, Yu-Tsung; Liao, Chun-Hsing; Sheng, Wang-Hui; Hsueh, Po-Ren

    2015-10-01

    Tedizolid is a novel, expanded-spectrum oxazolidinone with potent activity against a wide range of Gram-positive pathogens. A total of 425 isolates of Gram-positive bacteria were obtained consecutively from patients with acute bacterial skin and skin structure infections (ABSSSIs) or pneumonia. These isolates included methicillin-susceptible Staphylococcus aureus (MSSA) (n = 100), methicillin-resistant Staphylococcus aureus (MRSA) (n = 100), Streptococcus pyogenes (n = 50), Streptococcus agalactiae (n = 50), Streptococcus anginosus group (n = 75), Enterococcus faecalis (n = 50), and vancomycin-resistant enterococci (VRE) (Enterococcus faecium) (n = 50). The MICs of tedizolid and linezolid were determined by the agar dilution method. Tedizolid exhibited better in vitro activities than linezolid against MSSA (MIC90s, 0.5 versus 2 μg/ml), MRSA (MIC90s, 0.5 versus 2 μg/ml), S. pyogenes (MIC90s, 0.5 versus 2 μg/ml), S. agalactiae (MIC90s, 0.5 versus 2 μg/ml), Streptococcus anginosus group (MIC90s, 0.5 versus 2 μg/ml), E. faecalis (MIC90s, 0.5 versus 2 μg/ml), and VRE (MIC90s, 0.5 versus 2 μg/ml). The tedizolid MICs against E. faecalis (n = 3) and VRE (n = 2) intermediate to linezolid (MICs, 4 μg/ml) were 1 μg/ml and 0.5 μg/ml, respectively. The tedizolid MIC90s against S. anginosus, S. constellatus, and S. intermedius were 0.5, 1, and 0.5 μg/ml, respectively, and the rates of susceptibility based on the U.S. FDA MIC interpretive breakpoints to the isolates were 16%, 28%, and 72%, respectively. Tedizolid exhibited 2- to 4-fold better in vitro activities than linezolid against a variety of Gram-positive cocci associated with ABSSSIs and pneumonia. The lower susceptibilities of tedizolid against isolates of S. anginosus and S. constellatus than against those of S. intermedius in Taiwan were noted. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  15. In vitro activity of monoclonal and recombinant yeast killer toxin-like antibodies against antibiotic-resistant gram-positive cocci.

    PubMed Central

    Conti, S.; Magliani, W.; Arseni, S.; Dieci, E.; Frazzi, R.; Salati, A.; Varaldo, P. E.; Polonelli, L.

    2000-01-01

    BACKGROUND: Monoclonal (mAbKT) and recombinant single-chain (scFvKT) anti-idiotypic antibodies were produced to represent the internal image of a yeast killer toxin (KT) characterized by a wide spectrum of antimicrobial activity, including gram-positive cocci. Pathogenic eukaryotic and prokaryotic microorganisms, such as Candida albicans, Pneumocystis carinii, and a multidrug-resistant strain of Mycobacterium tuberculosis, presenting specific, although yet undefined, KT-cell wall receptors (KTR), have proven to be killed in vitro by mAbKT and scFvKT. mAbKT and scFvKT exert a therapeutic effect in vivo in experimental models of candidiasis and pneumocystosis by mimicking the functional activity of protective antibodies naturally produced in humans against KTR of infecting microorganisms. The swelling tide of concern over increasing bacterial resistance to antibiotic drugs gives the impetus to develop new therapeutic compounds against microbial threat. Thus, the in vitro bactericidal activity of mAbKT and scFvKT against gram-positive, drug-resistant cocci of major epidemiological interest was investigated. MATERIALS AND METHODS: mAbKT and scFvKT generated by hybridoma and DNA recombinant technology from the spleen lymphocytes of mice immunized with a KT-neutralizing monoclonal antibody (mAb KT4) were used in a conventional colony forming unit (CFU) assay to determine, from a qualitative point of view, their bactericidal activity against Staphylococcus aureus, S. haemolyticus, Enterococcus faecalis, E. faecium, and Streptococcus pneumoniae strains. These bacterial strains are characterized by different patterns of resistance to antibiotics, including methicillin, vancomycin, and penicillin. RESULTS: According to the experimental conditions adopted, no bacterial isolate proved to be resistant to the activity of mAbKT and scFvKT. CONCLUSIONS: scFvKT exerted a microbicidal activity against multidrug resistant bacteria, which may represent the basis for the drug modeling

  16. N,N-dimethylglycyl-amido derivative of minocycline and 6-demethyl-6-desoxytetracycline, two new glycylcyclines highly effective against tetracycline-resistant gram-positive cocci.

    PubMed

    Goldstein, F W; Kitzis, M D; Acar, J F

    1994-09-01

    The in vitro activities of the N,N-dimethylglycyl-amino derivative of minocycline (DMG-MINO) and 6-dimethyl-6-dexoxytetracycline (DMG-DMDOT), members of a new generation of tetracyclines, were evaluated by an agar dilution method and were compared with those of tetracycline and minocycline against 224 tetracycline-resistant and 73 tetracycline-susceptible recent clinical isolates of gram-positive cocci, including multiple-antibiotic-resistant methicillin-resistant Staphylococcus aureus and penicillin-resistant Streptococcus pneumoniae. The MICs of DMG-MINO and DMG-DMDOT were up to 500- to 2,000-fold lower than those of tetracycline against methicillin-resistant S. aureus and Streptococcus pneumoniae (MIC for 50% of strains tested [MIC50], < 0.06 microgram/ml). Against Streptococcus groups A, B, C, and G and Enterococcus faecalis, the MIC50 was 0.5 microgram/ml. MIC50s were greater only for coagulase-negative staphylococci (2 micrograms/ml). These data indicate that DMG-MINO and DMG-DMDOT are very potent drugs, and further in vitro and in vivo studies are warranted.

  17. The optimization and validation of the Biotyper MALDI-TOF MS database for the identification of Gram-positive anaerobic cocci.

    PubMed

    Veloo, A C M; de Vries, E D; Jean-Pierre, H; Justesen, U S; Morris, T; Urban, E; Wybo, I; van Winkelhoff, A J

    2016-09-01

    Gram-positive anaerobic cocci (GPAC) account for 24%-31% of the anaerobic bacteria isolated from human clinical specimens. At present, GPAC are under-represented in the Biotyper MALDI-TOF MS database. Profiles of new species have yet to be added. We present the optimization of the matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF MS) database for the identification of GPAC. Main spectral profiles (MSPs) were created for 108 clinical GPAC isolates. Identity was confirmed using 16S rRNA gene sequencing. Species identification was considered to be reliable if the sequence similarity with its closest relative was ≥98.7%. The optimized database was validated using 140 clinical isolates. The 16S rRNA sequencing identity was compared with the MALDI-TOF MS result. MSPs were added from 17 species that were not yet represented in the MALDI-TOF MS database or were under-represented (fewer than five MSPs). This resulted in an increase from 53.6% (75/140) to 82.1% (115/140) of GPAC isolates that could be identified at the species level using MALDI-TOF MS. An improved log score was obtained for 51.4% (72/140) of the strains. For strains with a sequence similarity <98.7% with their closest relative (n = 5) or with an inconclusive sequence identity (n = 4), no identification was obtained by MALDI-TOF MS or in the latter case an identity with one of its relatives. For some species the MSP of the type strain was not part of the confined cluster of the corresponding clinical isolates. Also, not all species formed a homogeneous cluster. It emphasizes the necessity of adding sufficient MSPs of human clinical isolates.

  18. Performance of the Vitek 2 system software version 5.03 in the bacterial identification and antimicrobial susceptibility test: evaluation study of clinical and reference strains of Gram-positive cocci.

    PubMed

    Paim, Thiago Galvão da Silva; Cantarelli, Vlademir Vicente; d'Azevedo, Pedro Alves

    2014-01-01

    The genera Enterococcus, Staphylococcus and Streptococcus are recognized as important Gram-positive human pathogens. The aim of this study was to evaluate the performance of Vitek 2 in identifying Gram-positive cocci and their antimicrobial susceptibilities. One hundred four isolates were analyzed to determine the accuracy of the automated system for identifying the bacteria and their susceptibility to oxacillin and vancomycin. The system correctly identified 77.9% and 97.1% of the isolates at the species and genus levels, respectively. Additionally, 81.8% of the Vitek 2 results agreed with the known antimicrobial susceptibility profiles. Vitek 2 correctly identified the commonly isolated strains; however, the limitations of the method may lead to ambiguous findings.

  19. [Consensus on antimicrobial sensitivity tests in gram-positive cocci. Subcommittee on Antimicrobials, SADEBAC (Argentinian Society of Clinical Bacteriology), Argentinian Association of Microbiology].

    PubMed

    Famiglietti, A; Quinteros, M; Predari, S C; Corso, A; Lopardo, H; Casellas, J M; Bantar, C; Couto, E; Galas, M; Goldberg, M; Gutkind, G; Kovensky Pupko, J; Marín, M; Nicola, F; Pasterán, F; Radice, M; Soloaga, R

    2003-01-01

    Antimicrobial susceptibility testing is mainly performed in Argentina by disk diffusion method, following National Committee for Clinical Laboratory Standards (NCCLS) recommendations. We worked out new recommendations for the reporting and interpretation of this test when dealing with gram-positive cocci, in accordance to local trends and epidemiology. General considerations for performing the diffusion assay, quality control, and an update on susceptibility testing for gram-positive cocci are reported in this first document. The present update should be considered as a group of recommendations summarized by Argentinean experts and as the result of a consensus meeting coordinated by the Subcomisión de Antimicrobianos of the Sociedad Argentina de Bacteriología Clínica (Asociación Argentina de Microbiología). Experts in antimicrobial agents were convened in order to prepare this final document. These recommendations take into account local needs, affordability and availability to be used in current practice, tending to contribute to the correct antimicrobial treatment election, according to the particular microorganism and the infection sites.

  20. Abscess-forming inflammatory granulation tissue with Gram-positive cocci and prominent eosinophil infiltration in cats: possible infection of methicillin-resistant Staphylococcus.

    PubMed

    Ozaki, K; Yamagami, T; Nomura, K; Haritani, M; Tsutsumi, Y; Narama, I

    2003-05-01

    We occasionally encounter feline cervical or mesenteric lesions diagnosed histopathologically as abscess or inflammatory granulation tissue with eosinophil infiltration. Gram-positive cocci accompany the lesions. In the present study, such lesions obtained from 27 cats were examined to evaluate the histopathologic features and the nature of the causative bacteria. The average age was 7.3 +/- 3.5 years. No sex predilection was observed. Most frequent locations of the lesions included the abdominal cavity with/without mesenteric lymph nodes (11/27, 41%) and subcutaneous tissue or lymph nodes of the neck (9/27, 33%). Common clinical presentation was a localized mass. Grossly, the lesions contained abscesses in the center and were surrounded by fibrous tissue. Microscopically, the necrotic zone contained bacterial colonies. Large numbers of eosinophils and macrophages infiltrated the area surrounding the necrotic tissue. The surrounding connective fiber-rich granulation tissue demarcated the eosinophilic abscess. The bacteria were Gram-positive cocci in 23 of the 27 cats and were positive for anti-staphylococcus antiserum in 19 of the 23 cats. In 15 out of 17 lesions, the colonies expressed immunoreactivity to penicillin-binding protein 2', which is a drug-resistance gene product of methicillin-resistant Staphylococcus (MRS) species. These findings suggest strongly that MRS causes this type of infectious lesion.

  1. Comparison of Three Commercial Rapid Identification Systems for the Unusual Gram-Positive Cocci Dolosigranulum pigrum, Ignavigranum ruoffiae, and Facklamia Species

    PubMed Central

    LaClaire, Leslye L.; Facklam, Richard R.

    2000-01-01

    We evaluated three rapid identification systems—The Biomerieux rapid ID 32 STREP (ID32), the BBL Crystal rapid gram-positive identification (Crystal), and the Remel IDS RapID STR (IDS) systems—for their ability to identify 7 strains of Alloiococcus otitidis, 27 strains of Dolosigranulum pigrum, 3 strains of Ignavigranum ruoffiae, and 18 strains of 4 different Facklamia species. Since none of these six species of gram-positive cocci are included in the identification databases for these systems, the correct identification for the strains tested should be “unacceptable ID” for the ID32 and Crystal systems or “no choice” for the IDS system. The ID32 system identified all 27 strains of D. pigrum, 6 of 18 Facklamia species, and 2 of 3 cultures of I. ruoffiae as “unacceptable ID.” The Crystal system identified 10 of 27 D. pigrum, 2 of 18 Facklamia species, and 2 of 3 I. ruoffiae strains as “unacceptable ID.” The IDS system identified only 1 culture of D. pigrum as “no choice,” but it also identified 2 cultures of D. pigrum as a “questionable microcode” and 19 cultures of D. pigrum as an “inadequate ID, E. faecalis 90%, S. intermedius 9%.” A total of 2 of the 18 cultures of Facklamia and all 3 of the I. ruoffiae cultures were correctly identified as “no choice.” The most common misidentifications of Facklamia species by the ID32 and IDS systems were as various Streptococcus species and as Gemella species. In the Crystal system, the most common erroneous identification was Micrococcus luteus. These data indicate the need for the commercial manufacturers of these products to update their databases to include newly described species of gram-positive cocci. PMID:10834950

  2. Novel physico-chemical diagnostic tools for high throughput identification of bovine mastitis associated gram-positive, catalase-negative cocci

    PubMed Central

    2014-01-01

    Background The routine diagnosis of Streptococcus spp. and other mastitis associated gram-positive, catalase-negative cocci is still based upon biochemical tests and serological methods, which frequently provide ambiguous identification results. We therefore aimed to establish an accurate identification system for differential diagnosis of mastitis associated Streptococcus spp. and related species using biophysical techniques such as Fourier-transform infrared (FTIR) spectroscopy and MALDI – TOF/MS. Results Based on a panel of 210 isolates from cases of bovine mastitis, an unsupervised FTIR spectral reference library was established and an artificial neural network (ANN) - assisted identification system was developed. All bacterial isolates were previously identified by species-specific PCR and/or 16S rRNA gene sequence analysis. An overall identification rate of 100% at species level for 173 strains unknown to the ANN and the library was achieved by combining ANN and the spectral database, thus demonstrating the suitability of our FTIR identification system for routine diagnosis. In addition, we investigated the potential of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of mastitis associated Streptococcus spp. and related bacteria. Using the Microflex LT System, MALDI Biotyper software™ (V3.3) we achieved an accuracy rate of 95.2%. A blind study, including 21 clinical samples from dairy cows, revealed a 100% correct species identification rate for FTIR and 90.5% for MALDI-TOF MS, indicating that these techniques are valuable tools for diagnosis. Conclusions This study clearly demonstrates that FTIR spectroscopy as well as MALDI-TOF MS can significantly improve and facilitate the identification and differentiation of mastitis associated Streptococcus spp. and related species. Although the FTIR identification system turned out being slightly superior to MALDI-TOF MS in terms of identification

  3. Antibacterial activity of Withania somnifera against Gram-positive isolates from pus samples

    PubMed Central

    Bisht, Punum; Rawat, Vinita

    2014-01-01

    Background: Withania somnifera is an important medicinal plant that has been used in Ayurvedic and indigenous medicine since ancient times. In the view of its varied therapeutic potential, it has also been the subject of considerable modern scientific attention. Attention has been drawn to antibacterial activity of the plant and its metabolites due to the challenge on growing antibacterial resistant pathogens. Aim: To examine the antimicrobial potential of leaf extract of W. somnifera against Gram-positive cocci. Materials and Methods: In this study, leaf extract of W. somnifera was used to examine their antimicrobial potential against Gram-positive cocci (n = 20) from pus samples of patients admitted in Government Medical College, Haldwani. Agar well diffusion method was used by taking methanolic leaf extract of W. somnifera. Results: It was observed that the methanolic leaf extract of W. somnifera was very effective in inhibiting the test pathogens including methicillin resistant Staphylococcus aureus and Enterococcus spp., with an average zone of inhibition of 20.6 mm and 19.4 mm at 2 mg/ml (100 μl) concentration, respectively. Conclusion: These results indicate that the antimicrobial property of W. somnifera leaf supports the traditional use of the plant in therapeutic use against microbial infections. PMID:25972723

  4. Heterogeneity of nonimmune immunoglobulin Fc reactivity among gram-positive cocci: description of three major types of receptors for human immunoglobulin G.

    PubMed

    Myhre, E B; Kronvall, G

    1977-09-01

    Two hundred and thirty strains of various gram-positive cocci were tested for quantitative, nonimmune binding of radiolabeled human polyclonal immunoglobulin G (IgG). The majority of coagulase-positive staphylococci and streptococci belonging to serogroups C and G showed a high uptake of IgG. The binding of immunoglobulin to group A streptococci was considerably less, with a number of strains completely negative. None of the pneumococcal or the group B or D streptococcal strains displayed any binding capacity. Heterogeneity of the IgG reactivity of various reactive strains was studied in an inhibition assay using 10 different animal serum pools. Three different inhibition patterns were seen, each of them revealing a striking degree of homogeneity within single bacterial species. Staphylococcus aureus and group A streptococci, respectively, constituted two homogeneous groups which differed markedly from each other and from C and G streptococci. No differences were observed between group C and G streptococci. Based on the profound differences between these homogeneous groups, three major types of Fc receptors could be defined. Type I and II Fc receptors were found on S. aureus and on group A streptococci, respectively. Fc receptor type III represented the immunoglobulin-binding structure of both group C and G streptococci.

  5. Direct inoculation method using BacT/ALERT 3D and BD Phoenix System allows rapid and accurate identification and susceptibility testing for both Gram-positive cocci and Gram-negative rods in aerobic blood cultures.

    PubMed

    Yonetani, Shota; Okazaki, Mitsuhiro; Araki, Koji; Makino, Hiroshi; Fukugawa, Yoko; Okuyama, Takahiro; Ohnishi, Hiroaki; Watanabe, Takashi

    2012-06-01

    This study describes a direct inoculation method using the automated BacT/ALERT 3D and the BD Phoenix System in combination for identification and susceptibility testing of isolates from positive blood cultures. Organism identification and susceptibility results were compared with the conventional method for 211 positive aerobic blood cultures. Of 110 Gram-positive cocci (GPCs), 98 (89.1%) isolates were correctly identified to the species level. Of 101 Gram-negative rods (GNRs), 98 (97.0%) isolates were correctly identified to the species level. The overall categorical agreement in antimicrobial susceptibility testing among the 110 GPCs was 92.7%, with 0.04% very major and 0.7% major error rates. The overall categorical agreement among 78 isolates of enterobacteria and 23 isolates of nonfermenters in GNRs was 99.5% and 91.1%, respectively, with no major errors identified. We conclude that, compared with previously reported direct inoculation methods, our method is superior in identification and susceptibility testing of GPCs.

  6. Prevalence and Characteristics of Surgical Site Infections Caused by Gram-negative Rod-shaped Bacteria from the Family Enterobacteriacae and Gram-positive Cocci from the Genus Staphylococcus in Patients who Underwent Surgical Procedures on Selected Surgical Wards.

    PubMed

    Tomaszewska-Kowalska, Małgorzata; Kołomecki, Krzysztof; Wieloch-Torzecka, Maria

    2016-10-01

    Surgical site infections on surgical wards are the most common cause of postoperative complications. Prevalence of surgical site infections depends on the surgical specialization. Analysis of the causes of surgical site infections allows to conclude that microorganisms from the patient's own microbiota - Gram-negative rod-shaped bacteria from the family Enterobacteriacae and from the patient's skin microbiota - Gram-positive cocci - Staphylococcus are the most common agents inducing surgical site infections. The aim of the study was to assess prevalence and characteristics of surgical site infections caused by Gram-negative rod-shaped bacteria from the family Eneterobacteriacae and Gram-positive cocci from the genus Staphylococcus in patients who underwent surgical procedures at the Regional Specialist Hospital named after M. Copernika in Łódź on selected surgical wards.

  7. Gram-positive bacteria of marine origin: a numerical taxonomic study on Mediterranean isolates.

    PubMed

    Ortigosa, M; Garay, E; Pujalte, M J

    1997-12-01

    A numerical taxonomic study was performed on 65 Gram-positive wild strains of heterotrophic, aerobic, marine bacteria, and 9 reference strains. The isolates were obtained from oysters and seawater sampled monthly over one year, by direct plating on Marine Agar. The strains were characterized by 96 morphological, biochemical, physiological and nutritional tests. Clustering yielded 13 phena at 0.62 similarity level (Sl coefficient). Only one of the seven phena containing wild isolates could be identified (Bacillus marinus). A pronounced salt requirement was found in most isolates.

  8. Isolation of highly active monoclonal antibodies against multiresistant gram-positive bacteria.

    PubMed

    Rossmann, Friederike S; Laverde, Diana; Kropec, Andrea; Romero-Saavedra, Felipe; Meyer-Buehn, Melanie; Huebner, Johannes

    2015-01-01

    Multiresistant nosocomial pathogens often cause life-threatening infections that are sometimes untreatable with currently available antibiotics. Staphylococci and enterococci are the predominant Gram-positive species associated with hospital-acquired infections. These infections often lead to extended hospital stay and excess mortality. In this study, a panel of fully human monoclonal antibodies was isolated from a healthy individual by selection of B-cells producing antibodies with high opsonic killing against E. faecalis 12030. Variable domains (VH and VL) of these immunoglobulin genes were amplified by PCR and cloned into an eukaryotic expression vector containing the constant domains of a human IgG1 molecule and the human lambda constant domain. These constructs were transfected into CHO cells and culture supernatants were collected and tested by opsonophagocytic assay against E. faecalis and S. aureus strains (including MRSA). At concentrations of 600 pg/ml, opsonic killing was between 40% and 70% against all strains tested. Monoclonal antibodies were also evaluated in a mouse sepsis model (using S. aureus LAC and E. faecium), a mouse peritonitis model (using S. aureus Newman and LAC) and a rat endocarditis model (using E. faecalis 12030) and were shown to provide protection in all models at a concentration of 4 μg/kg per animal. Here we present a method to produce fully human IgG1 monoclonal antibodies that are opsonic in vitro and protective in vivo against several multiresistant Gram-positive bacteria. The monoclonal antibodies presented in this study are significantly more effective compared to another monoclonal antibody currently in clinical trials.

  9. Isolation of Highly Active Monoclonal Antibodies against Multiresistant Gram-Positive Bacteria

    PubMed Central

    Rossmann, Friederike S.; Laverde, Diana; Kropec, Andrea; Romero-Saavedra, Felipe; Meyer-Buehn, Melanie; Huebner, Johannes

    2015-01-01

    Multiresistant nosocomial pathogens often cause life-threatening infections that are sometimes untreatable with currently available antibiotics. Staphylococci and enterococci are the predominant Gram-positive species associated with hospital-acquired infections. These infections often lead to extended hospital stay and excess mortality. In this study, a panel of fully human monoclonal antibodies was isolated from a healthy individual by selection of B-cells producing antibodies with high opsonic killing against E. faecalis 12030. Variable domains (VH and VL) of these immunoglobulin genes were amplified by PCR and cloned into an eukaryotic expression vector containing the constant domains of a human IgG1 molecule and the human lambda constant domain. These constructs were transfected into CHO cells and culture supernatants were collected and tested by opsonophagocytic assay against E. faecalis and S. aureus strains (including MRSA). At concentrations of 600 pg/ml, opsonic killing was between 40% and 70% against all strains tested. Monoclonal antibodies were also evaluated in a mouse sepsis model (using S. aureus LAC and E. faecium), a mouse peritonitis model (using S. aureus Newman and LAC) and a rat endocarditis model (using E. faecalis 12030) and were shown to provide protection in all models at a concentration of 4 μg/kg per animal. Here we present a method to produce fully human IgG1 monoclonal antibodies that are opsonic in vitro and protective in vivo against several multiresistant Gram-positive bacteria. The monoclonal antibodies presented in this study are significantly more effective compared to another monoclonal antibody currently in clinical trials. PMID:25706415

  10. Matrix-assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) as a Reliable Tool to Identify Species of Catalase-negative Gram-positive Cocci not Belonging to the Streptococcus Genus.

    PubMed

    Almuzara, Marisa; Barberis, Claudia; Velázquez, Viviana Rojas; Ramirez, Maria Soledad; Famiglietti, Angela; Vay, Carlos

    2016-01-01

    To evaluate the performance of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) by using 190 Catalase-negative Gram-Positive Cocci (GPC) clinical isolates. All isolates were identified by conventional phenotypic tests following the proposed scheme by Ruoff and Christensen and MALDI-TOF MS (Bruker Daltonics, BD, Bremen, Germany). Two different extraction methods (direct transfer formic acid method on spot and ethanol formic acid extraction method) and different cut-offs for genus/specie level identification were used. The score cut-offs recommended by the manufacturer (≥ 2.000 for species-level, 1.700 to 1.999 for genus level and <1.700 no reliable identification) and lower cut-off scores (≥1.500 for genus level, ≥ 1.700 for species-level and score <1.500 no reliable identification) were considered for identification. A minimum difference of 10% between the top and next closest score was required for a different genus or species. MALDI-TOF MS identification was considered correct when the result obtained from MS database agreed with the phenotypic identification result. When both methods gave discordant results, the 16S rDNA or sodA genes sequencing was considered as the gold standard identification method. The results obtained by MS concordant with genes sequencing, although discordant with conventional phenotyping, were considered correct. MS results discordant with 16S or sodA identification were considered incorrect. Using the score cut-offs recommended by the manufacturer, 97.37% and 81.05% were correctly identified to genus and species level, respectively. On the other hand, using lower cut-off scores for identification, 97.89% and 94.21% isolates were correctly identified to genus and species level respectively by MALDI-TOF MS and no significant differences between the results obtained with two extraction methods were obtained. The results obtained suggest that MALDI-TOF MS has the potential of being an

  11. Matrix-assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry (MALDI-TOF MS) as a Reliable Tool to Identify Species of Catalase-negative Gram-positive Cocci not Belonging to the Streptococcus Genus

    PubMed Central

    Almuzara, Marisa; Barberis, Claudia; Velázquez, Viviana Rojas; Ramirez, Maria Soledad; Famiglietti, Angela; Vay, Carlos

    2016-01-01

    Objective: To evaluate the performance of matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) by using 190 Catalase-negative Gram-Positive Cocci (GPC) clinical isolates. Methods: All isolates were identified by conventional phenotypic tests following the proposed scheme by Ruoff and Christensen and MALDI-TOF MS (Bruker Daltonics, BD, Bremen, Germany). Two different extraction methods (direct transfer formic acid method on spot and ethanol formic acid extraction method) and different cut-offs for genus/specie level identification were used. The score cut-offs recommended by the manufacturer (≥ 2.000 for species-level, 1.700 to 1.999 for genus level and <1.700 no reliable identification) and lower cut-off scores (≥1.500 for genus level, ≥ 1.700 for species-level and score <1.500 no reliable identification) were considered for identification. A minimum difference of 10% between the top and next closest score was required for a different genus or species. MALDI-TOF MS identification was considered correct when the result obtained from MS database agreed with the phenotypic identification result. When both methods gave discordant results, the 16S rDNA or sodA genes sequencing was considered as the gold standard identification method. The results obtained by MS concordant with genes sequencing, although discordant with conventional phenotyping, were considered correct. MS results discordant with 16S or sodA identification were considered incorrect. Results: Using the score cut-offs recommended by the manufacturer, 97.37% and 81.05% were correctly identified to genus and species level, respectively. On the other hand, using lower cut-off scores for identification, 97.89% and 94.21% isolates were correctly identified to genus and species level respectively by MALDI-TOF MS and no significant differences between the results obtained with two extraction methods were obtained. Conclusion: The results obtained suggest that MALDI

  12. Isolation and Characterization of Four Gram-Positive Nickel-Tolerant Microorganisms from Contaminated Sediments

    SciTech Connect

    Van Nostrand, J. D.; Khijniak, T. V.; Gentry, T. J.; Novak, M. T.; Sowder, A. G.; Zhou, J. Z.; Bertsch, P. M.; Morris, P. J.

    2007-01-01

    Microbial communities from riparian sediments contaminated with high levels of Ni and U were examined for metal-tolerant microorganisms. Isolation of four aerobic Ni-tolerant, Gram-positive heterotrophic bacteria indicated selection pressure from Ni. These isolates were identified as Arthrobacter oxydans NR-1, Streptomyces galbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatospora cystarginea NR-4 based on partial 16S rDNA sequences. A functional gene microarray containing gene probes for functions associated with biogeochemical cycling, metal homeostasis, and organic contaminant degradation showed little overlap among the four isolates. Fifteen of the genes were detected in all four isolates with only two of these related to metal resistance, specifically to tellurium. Each of the four isolates also displayed resistance to at least one of six antibiotics tested, with resistance to kanamycin, gentamycin, and ciprofloxacin observed in at least two of the isolates. Further characterization of S. aureofaciens NR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Ni tolerance constitutively. In addition, both were able to grow in higher concentrations of Ni at pH 6 as compared with pH 7 (42.6 and 8.5 mM Ni at pH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examined in these two isolates; a similar pH-dependent metal tolerance was observed when grown with Co and Zn. Neither isolate was tolerant to Cd. These findings suggest that Ni is exerting a selection pressure at this site for metal-resistant actinomycetes.

  13. Clinical Significance of Commensal Gram-Positive Rods Routinely Isolated from Patient Samples.

    PubMed

    Leal, Sixto M; Jones, Melissa; Gilligan, Peter H

    2016-12-01

    Commensal bacteria from the skin and mucosal surfaces are routinely isolated from patient samples and considered contaminants. The majority of these isolates are catalase-positive Gram-positive rods from multiple genera routinely classified as diphtheroids. These organisms can be seen upon Gram staining of clinical specimens or can be isolated as the predominant or pure species in culture, raising a priori suspicion of a possible involvement in infection. With the development and adoption of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), suspicious isolates are now routinely identified to the species level. In this study, we performed a retrospective data review (2012 to 2015) and utilized site-specific laboratory criteria and chart reviews to identify species within the diphtheroid classification representative of true infection versus contamination. Our data set included 762 isolates from 13 genera constituting 41 bacterial species. Only 18% represented true infection, and 82% were deemed contaminants. Clinically significant isolates were identified in anaerobic wounds (18%), aerobic wounds (30%), blood (5.5%), urine (22%), cerebrospinal fluid (24%), ophthalmologic cultures (8%), and sterile sites (20%). Organisms deemed clinically significant included multiple Actinomyces species in wounds, Propionibacterium species in joints and cerebrospinal fluid associated with central nervous system hardware, Corynebacterium kroppenstedtii (100%) in breast, and Corynebacterium striatum in multiple sites. Novel findings include clinically significant urinary tract infections by Actinomyces neuii (21%) and Corynebacterium aurimucosum (21%). Taken together, these findings indicate that species-level identification of diphtheroids isolated with a priori suspicion of infection is essential to accurately determine whether an isolate belongs to a species associated with specific types of infection.

  14. Production of acylated homoserine lactone by gram-positive bacteria isolated from marine water.

    PubMed

    Biswa, Pramal; Doble, Mukesh

    2013-06-01

    Acylated homoserine lactone (AHL)-based quorum sensing (QS) has been reported to be present only in Gram-negative microorganisms. Isolation of a novel Gram-positive microorganism from sea water, capable of producing AHL, is reported here. The isolate (GenBank: JF915892, designated as MPO) belonging to the Exiguobacterium genera is capable of inducing the AHL bioreporters, namely Chromobacterium violaceum CV026, Agrobacterium tumefaceins A136, and E. coli JM 109(psb1075). This inducer is characterized as C3-oxo-octanoyl homoserine lactone (OOHL), and its production reaches a maximum of 15.6 μg L(-1), during the stationary growth phase of the organism. MPO extract when exogenously added inhibits the formation of biofilm for the same organism and lowers the extracellular polymeric substances, indicating an AHL-associated phenotypic trait. The isolated sequence of a probable LuxR homolog from MPO (designated as ExgR) shows similar functional domains and contains conserved residues in LuxR from other known bacterial QS LuxR regulators. Also present immediately downstream to ExgR was found a sequence showing homology to known LuxI synthase of Pseudomonas putida. qPCR analysis suggests an increment in exgR mRNA on addition of AHL, further proving the role of ExgR as a QS regulator.

  15. Isolating "Unknown" Bacteria in the Introductory Microbiology Laboratory: A New Selective Medium for Gram-Positives.

    ERIC Educational Resources Information Center

    McKillip, John L.; Drake, MaryAnne

    1999-01-01

    Describes the development, preparation, and use of a medium that can select against a wide variety of Gram-negative bacteria while still allowing growth and differentiation of a wide range of Gram-positives. (WRM)

  16. Isolating "Unknown" Bacteria in the Introductory Microbiology Laboratory: A New Selective Medium for Gram-Positives.

    ERIC Educational Resources Information Center

    McKillip, John L.; Drake, MaryAnne

    1999-01-01

    Describes the development, preparation, and use of a medium that can select against a wide variety of Gram-negative bacteria while still allowing growth and differentiation of a wide range of Gram-positives. (WRM)

  17. Paucisalibacillus globulus gen. nov., sp. nov., a Gram-positive bacterium isolated from potting soil.

    PubMed

    Nunes, Inês; Tiago, Igor; Pires, Ana Luísa; da Costa, Milton S; Veríssimo, António

    2006-08-01

    A Gram-positive bacterium, designated B22(T), was isolated from potting soil produced in Portugal. This organism is a catalase-positive, oxidase-negative, motile, spore-forming, aerobic rod that grows optimally at 37 degrees C and pH 8.0-8.5. Optimal growth occurs in media containing 1 % (w/v) NaCl, although the organism can grow in 0-8 % NaCl. The cell wall peptidoglycan is of the A4alpha type with a cross-linkage containing d-Asp. The major respiratory quinone is menaquinone 7 and the major fatty acids are anteiso-15 : 0, anteiso-17 : 0 and iso-15 : 0. The DNA G+C content is 37.9 mol%. Phylogenetic analysis of 16S rRNA gene sequences revealed that strain B22(T) formed a new branch within the family Bacillaceae. The novel isolate is phylogenetically closely related to members of genera of moderately halophilic bacilli and formed a coherent cluster with species of the genera Salinibacillus, Virgibacillus, Oceanobacillus and Lentibacillus, supported by bootstrap analysis at a confidence level of 71 %. Strain B22(T) exhibited 16S rRNA gene pairwise sequence similarity values of 94.7-94.3 % with members of the genus Salinibacillus, 95.1-92.8 % with members of the genus Virgibacillus, 94.7-93.2 % with members of the genus Oceanobacillus and 93.1-92.3 % with members of the genus Lentibacillus. On the basis of phylogenetic analysis and physiological and biochemical characteristics, it is proposed that strain B22(T) represents a novel species in a new genus, Paucisalibacillus globulus gen. nov., sp. nov. Strain B22(T) (=LMG 23148(T)=CIP 108857(T)) is the type strain of Paucisalibacillus globulus.

  18. Isolation and Characterization of Gram-Positive Piezophilic Bacteria from Deep Marine Subsurface Sediment

    NASA Astrophysics Data System (ADS)

    Runko, G. M.; Fang, J.; Kato, C.

    2014-12-01

    The marine deep biosphere remains as the least studied of all of Earth's habitats and is inadequately understood, but is extremely important to understand the impacts that microbes have on global biogeochemical cycles. Sediment samples were obtained during IODP Expedition 337 in the western Pacific Ocean, from 1,498 meters below the seafloor (mbsf; samples 6R3), 1,951-1,999 mbsf (19R1), and 2,406 mbsf (29R7). These samples were initially mixed with marine broth and cultivated under anaerobic conditions at pressure of 35 MPa (megapascal) and temperatures of 35° C, 45° C, and 55° C for 3 months on board the Chikyu. Single colonies were isolated via plating on marine broth. Then, six strains of bacteria were identified, 6R3-1, 6R3-15, 19R1-5, 29R7-12B, 29R7-12M, and 29R7-12S. The six strains were then examined for optimal growth temperature and pressure. These organisms are Gram-positive, spore-forming, facultative anaerobic piezophilic bacteria. Major fatty acids are anteiso-15:0, anteiso-17:0 and iso-15:0. Phylogenetic analysis of 16S rRNA gene sequences revealed that the isolates are closely related to Virgibacillus pantothenticus, Robinsoniella peoriensis, and Bacillus subtilis. Because of their abundance in the deep marine subsurface, these microorganisms likely play an important role in sustaining the deep microbial ecosystem and influencing biogeochemical cycles in the deep biosphere.

  19. Isolation of gram-positive rods that resemble but are clearly distinct from Actinomyces pyogenes from mixed wound infections.

    PubMed Central

    Wüst, J; Lucchini, G M; Lüthy-Hottenstein, J; Brun, F; Altwegg, M

    1993-01-01

    Beginning in 1990, gram-positive rods resembling Actinomyces pyogenes were found with increasing frequency in mixed cultures from various infectious processes, most of them from patients with otitis, empyema, pilonidal cysts, perianal abscesses, and decubitus ulcers. Ribotyping and hybridization showed that these gram-positive rods could be divided into five groups not related to known Actinomyces species. Biochemical markers for reliable differentiation into these groups, however, could not be found. Therefore, naming new species is not warranted unless parameters are discovered that allow identification without DNA hybridization. These gram-positive rods have been isolated only in mixed cultures with anaerobes, Staphylococcus aureus, Streptococcus "milleri," enterococci, and gram-negative rods. Their exact role in these possibly synergistic infections needs further investigation. Images PMID:8501213

  20. In vitro activity of paldimycin (U-70138F) against gram-positive bacteria isolated from patients with cancer.

    PubMed Central

    Rolston, K V; LeBlanc, B; Ho, D H; Bodey, G P

    1987-01-01

    The in vitro activity of paldimycin, a novel antimicrobial agent, was compared with that of vancomycin against 306 gram-positive isolates (representing 12 bacterial species) obtained from patients with cancer. Paldimycin had lower MICs for 90% of isolates than vancomycin did against most isolates tested. Its activity, however, was medium and pH dependent, being greatest in Nutrient broth at a pH of 6.8. PMID:3606069

  1. Isolation and Characterization of Gram-Positive Biosurfactant-Producing Halothermophilic Bacilli From Iranian Petroleum Reservoirs

    PubMed Central

    Zargari, Saeed; Ramezani, Amin; Ostvar, Sassan; Rezaei, Rasool; Niazi, Ali; Ayatollahi, Shahab

    2014-01-01

    Background: Petroleum reservoirs have long been known as the hosts of extremophilic microorganisms. Some of these microorganisms are known for their potential biotechnological applications, particularly production of extra and intracellular polymers and enzymes. Objectives: Here, 14 petroleum liquid samples from southern Iranian oil reservoirs were screened for presence of biosurfactant‐producing halothermophiles. Materials and Methods: Mixture of the reservoir fluid samples with a minimal growth medium was incubated under an N2 atmosphere in 40°C; 0.5 mL samples were transferred from the aqueous phase to agar plates after 72 hours of incubation; 100 mL cell cultures were prepared using the MSS-1 (mineral salt solution 1) liquid medium with 5% (w/v) NaCl. The time-course samples were analyzed by recording the absorbance at 600 nm using a spectrophotometer. Incubation was carried out in 40°C with mild shaking in aerobic conditions. Thermotolerance was evaluated by growing the isolates at 40, 50, 60 and 70°C with varying NaCl concentrations of 5% and 10% (w/v). Halotolerance was evaluated using NaCl concentrations of 5%, 10%, 12.5% and 15% (w/v) and incubating them at 40°C under aerobic and anaerobic conditions. Different phenotypic characteristics were evaluated, as outlined in Bergey's manual of determinative bacteriology. Comparing 16S rDNA sequences is one of the most powerful tools for classification of microorganisms. Results: Among 34 isolates, 10 demonstrated biosurfactant production and growth at temperatures between 40°C and 70°C in saline media containing 5%‐15% w/v NaCl. Using partial 16S rDNA sequencing (and amplified ribosomal DNA restriction analysis [ARDRA]) and biochemical tests (API tests 20E and 50 CHB), all the 10 isolates proved to be facultative anaerobic, Gram-positive moderate thermohalophiles of the genus Bacillus (B. thermoglucosidasius, B. thermodenitrificans, B. thermoleovorans, B. stearothermophilus and B. licheniformis

  2. In Vitro Activities of a New Lipopeptide, HMR 1043, against Susceptible and Resistant Gram-Positive Isolates

    PubMed Central

    Bemer, Pascale; Juvin, Marie-Emmanuelle; Bryskier, Andre; Drugeon, Henri

    2003-01-01

    The purpose of this study was to compare the activity of HMR 1043 with those of daptomycin and teicoplanin against gram-positive isolates. Susceptibility tests were performed for 52 strains, 26 parental strains, including staphylococcal, streptococcal, enterococcal, and listerial strains, and 26 HMR 1043-resistant mutants obtained from parental strains by using the Szybalski method. Agar dilution and disk diffusion susceptibility tests were performed by the procedures outlined by the NCCLS. HMR 1043 demonstrated good activity against susceptible and resistant gram-positive bacteria. The activity of HMR 1043 in vitro was less influenced by the presence of calcium ions than that of daptomycin. Susceptibility test breakpoints were not defined because of the poor correlation coefficients obtained with the different disks tested. PMID:12937020

  3. In vitro activities of a new lipopeptide, HMR 1043, against susceptible and resistant gram-positive isolates.

    PubMed

    Bemer, Pascale; Juvin, Marie-Emmanuelle; Bryskier, Andre; Drugeon, Henri

    2003-09-01

    The purpose of this study was to compare the activity of HMR 1043 with those of daptomycin and teicoplanin against gram-positive isolates. Susceptibility tests were performed for 52 strains, 26 parental strains, including staphylococcal, streptococcal, enterococcal, and listerial strains, and 26 HMR 1043-resistant mutants obtained from parental strains by using the Szybalski method. Agar dilution and disk diffusion susceptibility tests were performed by the procedures outlined by the NCCLS. HMR 1043 demonstrated good activity against susceptible and resistant gram-positive bacteria. The activity of HMR 1043 in vitro was less influenced by the presence of calcium ions than that of daptomycin. Susceptibility test breakpoints were not defined because of the poor correlation coefficients obtained with the different disks tested.

  4. Evidence for Direct Electron Transfer by a Gram-Positive Bacterium Isolated from a Microbial Fuel Cell▿†

    PubMed Central

    Wrighton, K. C.; Thrash, J. C.; Melnyk, R. A.; Bigi, J. P.; Byrne-Bailey, K. G.; Remis, J. P.; Schichnes, D.; Auer, M.; Chang, C. J.; Coates, J. D.

    2011-01-01

    Despite their importance in iron redox cycles and bioenergy production, the underlying physiological, genetic, and biochemical mechanisms of extracellular electron transfer by Gram-positive bacteria remain insufficiently understood. In this work, we investigated respiration by Thermincola potens strain JR, a Gram-positive isolate obtained from the anode surface of a microbial fuel cell, using insoluble electron acceptors. We found no evidence that soluble redox-active components were secreted into the surrounding medium on the basis of physiological experiments and cyclic voltammetry measurements. Confocal microscopy revealed highly stratified biofilms in which cells contacting the electrode surface were disproportionately viable relative to the rest of the biofilm. Furthermore, there was no correlation between biofilm thickness and power production, suggesting that cells in contact with the electrode were primarily responsible for current generation. These data, along with cryo-electron microscopy experiments, support contact-dependent electron transfer by T. potens strain JR from the cell membrane across the 37-nm cell envelope to the cell surface. Furthermore, we present physiological and genomic evidence that c-type cytochromes play a role in charge transfer across the Gram-positive bacterial cell envelope during metal reduction. PMID:21908627

  5. Bactericidal effect of ultraviolet C (UVC), direct and filtered through transparent plastic, on gram-positive cocci: an in vitro study.

    PubMed

    Rao, Bhamini K; Kumar, Pramod; Rao, Sugandhi; Gurung, Bimala

    2011-07-01

    The prevalence of wound infections caused by multidrug-resistant (MDR) bacteria is increasing along with concern about widespread use of antibiotics. In vitro studies have shown that ultraviolet radiation, especially UVC, is both an effective bactericidal and antifungal. However, evidence about its bactericidal effect on wounds covered with transparent dressings remains inconclusive. Transparent dressings are used to retain moisture over the wound as part of an intermittent negative pressure dressing-the Limited Access Dressing (LAD) technique. Because this dressing is designed to remain in place for a number of days, an in vitro study was conducted to explore the bactericidal effect of direct and indirect UVR through a transparent 0.15-mm thick transparent polythene sheet on Gram-positive cocci. Six bacterial strains were inoculated to sheep blood agar (SBA) plates and exposed to direct and filtered UVC (254 nm) for 5, 10, 15, 20, 25, and 30 seconds with one media serving as a control (no UVC exposure). Plates were subsequently incubated for 24 hours and bacterial growth observed. Each set of experiment was repeated three times. Direct UVC was shown to have good bactericidal effect (100% eradication of organisms inoculated) at durations ranging from a minimum of 5 seconds (methicillin-resistant, coagulase-negative Staphylococcus and Streptococcus pyogenes) to a maximum of 15 seconds (methicillin-susceptible Staphylococcus aureus and Enterococci species). No bactericidal effect was observed when UVC was filtered through a 0.15-mm thick transparent polythene sheet. The results confirm the bactericidal effect of UVC in vitro and suggest that this effect can be achieved after a very short period of time. At the same time, film dressings appear to filter UVC. This may help protect skin from exposure to UVC but also limits its utility for use with the LAD technique. In vivo studies to evaluate the shortest effective UVC treatment duration and follow-up clinical studies

  6. Five-Year Summary of In Vitro Activity and Resistance Mechanisms of Linezolid against Clinically Important Gram-Positive Cocci in the United States from the LEADER Surveillance Program (2011 to 2015).

    PubMed

    Pfaller, Michael A; Mendes, Rodrigo E; Streit, Jennifer M; Hogan, Patricia A; Flamm, Robert K

    2017-07-01

    This report describes linezolid susceptibility testing results for 6,741 Gram-positive pathogens from 60 U.S. sites collected during 2015 for the LEADER Program. In addition, the report summarizes linezolid in vitro activity, resistance mechanisms, and molecular typing obtained for 2011 to 2015. During 2015, linezolid showed potent activity in testing against Staphylococcus aureus, inhibiting >99.9% of 3,031 isolates at ≤2 µg/ml. Similarly, linezolid showed coverage against 99.2% of coagulase-negative staphylococci, 99.7% of enterococci, and 100.0% of Streptococcus pneumoniae, virdans group, and beta-hemolytic streptococcus isolates tested. The overall linezolid resistance rate remained a modest <1% from 2011 to 2015. Staphylococci, especially Staphylococcus epidermidis, showed a range of linezolid resistance mechanisms. Increased annual trends for the presence of cfr among Staphylococcus aureus isolates were not observed, but 64.3% (9/14) of the isolates with decreased susceptibility (MIC, ≥4 µg/ml) to linezolid carried this transferrable gene (2011 to 2015). The cfr gene was detected in 21.9% (7/32) of linezolid-resistant staphylococci other than S. aureus from 2011 to 2015. The optrA gene was noted in half (2/4) of the population of linezolid-nonsusceptible Enterococcus faecalis isolates from 2011 to 2015, while linezolid-nonsusceptible Enterococcus faecium isolates showed alterations predominantly (16/16) in the 23S rRNA gene (G2576T). This report confirms a long record of linezolid activity against Gram-positive isolates in the United States since regulatory approval in 2000 and reports the oxazolidinones evolving resistance mechanisms. Copyright © 2017 American Society for Microbiology.

  7. Production of a bacteriocin by a poultry derived Campylobacter jejuni isolate with antimicrobial activity against Clostridium perfringens and other Gram positive bacteria.

    USDA-ARS?s Scientific Manuscript database

    We have purified a bacteriocin peptide (termed CUV-3), produced by a poultry cecal isolate of Campylobacter jejuni (strain CUV-3) with inhibitory activity against Gram positive bacteria including Clostridium perfringens (38 strains), Staphylococcus aureus, Staphylococcus epidermidis and Listeria mon...

  8. [GEIPC-SEIMC (Study Group for Infections in the Critically Ill Patient of the Spanish Society for Infectious Diseases and Clinical Microbiology) and GTEI-SEMICYUC ( Working Group on Infectious Diseases of the Spanish Society of Intensive Medicine, Critical Care, and Coronary Units) recommendations for antibiotic treatment of gram-positive cocci infections in the critical patient].

    PubMed

    Astigarraga, P M Olaechea; Montero, J Garnacho; Cerrato, S Grau; Colomo, O Rodríguez; Martínez, M Palomar; Crespo, R Zaragoza; García-Paredes, P Muñoz; Cerdá, E Cerdá; Lerma, F Alvarez

    2007-01-01

    In recent years, an increment of infections caused by gram-positive cocci has been documented in nosocomial and hospital-acquired-infections. In diverse countries, a rapid development of resistance to common antibiotics against gram-positive cocci has been observed. This situation is exceptional in Spain but our country might be affected in the near future. New antimicrobials active against these multi-drug resistant pathogens are nowadays available. It is essential to improve our current knowledge about pharmacokinetic properties of traditional and new antimicrobials to maximize its effectiveness and to minimize toxicity. These issues are even more important in critically ill patients because inadequate empirical therapy is associated with therapeutic failure and a poor outcome. Experts representing two scientific societies (Grupo de estudio de Infecciones en el Paciente Crítico de la SEIMC and Grupo de trabajo de Enfermedades Infecciosas de la SEMICYUC) have elaborated a consensus document based on the current scientific evidence to summarize recommendations for the treatment of serious infections caused by gram-positive cocci in critically ill patients.

  9. Isolation and Characterization of Four Gram-PositiveNickel-Tolerant Microorganisms from Contaminated Riparian Sediments

    SciTech Connect

    Van Nostrand, Joy D.; Khijniak, Tatiana V.; Gentry, Terry J.; Novak, Michelle T.; Sowder, Andrew G.; Zhou, Jizhong Z.; Bertsch, PaulM.; Morris, Pamela J.

    2006-08-30

    Microbial communities from riparian sediments contaminatedwith high levels of Ni and U were examined for metal-tolerantmicroorganisms. Isolation of four aerobic Ni-tolerant, Gram-positiveheterotrophic bacteria indicated selection pressure from Ni. Theseisolates were identified as Arthrobacter oxydans NR-1, Streptomycesgalbus NR-2, Streptomyces aureofaciens NR-3, and Kitasatosporacystarginea NR-4 based on partial 16S rDNA sequences. A functional genemicroarray containing gene probes for functions associated withbiogeochemical cycling, metal homeostasis, and organic contaminantdegradation showed little overlap among the four isolates. Fifteen of thegenes were detected in all four isolates with only two of these relatedto metal resistance, specifically to tellurium. Each of the four isolatesalso displayed resistance to at least one of six antibiotics tested, withresistance to kanamycin, gentamycin, and ciprofloxacin observed in atleast two of the isolates. Further characterization of S. aureofaciensNR-3 and K. cystarginea NR-4 demonstrated that both isolates expressed Nitolerance constitutively. In addition, both were able to grow in higherconcentrations of Ni at pH 6 as compared to pH 7 (42.6 and 8.5 mM Ni atpH 6 and 7, respectively). Tolerance to Cd, Co, and Zn was also examinedin these two isolates; a similar pH-dependent metal tolerance wasobserved when grown with Co and Zn. Neither isolate was tolerant to Cd.These findings suggest that Ni is exerting a selection pressure at thissite for metal-resistant actinomycetes.

  10. Combination of phage and Gram-positive bacterial display of human antibody repertoires enables isolation of functional high affinity binders.

    PubMed

    Hu, Francis Jingxin; Volk, Anna-Luisa; Persson, Helena; Säll, Anna; Borrebaeck, Carl; Uhlen, Mathias; Rockberg, Johan

    2017-08-01

    Surface display couples genotype with a surface exposed phenotype and thereby allows screening of gene-encoded protein libraries for desired characteristics. Of the various display systems available, phage display is by far the most popular, mainly thanks to its ability to harbour large size libraries. Here, we describe the first use of a Gram-positive bacterial host for display of a library of human antibody genes which, when combined with phage display, provides ease of use for screening, sorting and ranking by flow cytometry. We demonstrate the utility of this method by identifying low nanomolar affinity scFv fragments towards human epidermal growth factor receptor 2 (HER2). The ranking and performance of the scFv isolated by flow sorting in surface-immobilised form was retained when expressed as soluble scFv and analysed by biolayer interferometry, as well as after expression as full-length antibodies in mammalian cells. We also demonstrate the possibility of using Gram-positive bacterial display to directly improve the affinity of the identified binders via an affinity maturation step using random mutagenesis and flow sorting. This combined approach has the potential for a more complete scan of the antibody repertoire and for affinity maturation of human antibody formats. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  11. Quadrisphaera granulorum gen. nov., sp. nov., a Gram-positive polyphosphate-accumulating coccus in tetrads or aggregates isolated from aerobic granules.

    PubMed

    Maszenan, Abdul Majid; Tay, Joo-Hwa; Schumann, Peter; Jiang, He-Long; Tay, Stephen Tiong-Lee

    2005-09-01

    A Gram-positive bacterium, designated strain AG019(T), was isolated by micromanipulation from aerobic granules obtained from a laboratory-scale sequencing batch reactor. This isolate grew axenically as cocci clustered predominantly in tetrads, and was morphologically similar to the dominant organisms observed in the biomass. The morphology also resembled that of the tetrad-forming organisms commonly seen in activated sludge samples. Strain AG019(T) was found to be an oxidase-negative, catalase-positive, non-motile aerobe that does not reduce nitrate and grows at temperatures between 15 and 40 degrees C, with an optimum at 37 degrees C. The pH range for growth was 5.0-9.0, with an optimum at pH 7.5. Strain AG019(T) contained a peptidoglycan with directly cross-linked meso-diaminopimelic acid (type A1gamma) and lacked mycolic acids. The G+C content of the DNA was 75 mol%. Menaquinone MK-8(H(2)) was the major isoprenoid quinone. The bacterium stained positively for intracellular polyphosphate granules but not for poly-beta-hydroxyalkanoates. It produced capsular material and showed autoaggregation ability. Phenotypic and 16S rRNA gene analyses showed that the bacterium differed sufficiently from its closest phylogenetic relatives, namely members of the suborder Frankineae, which includes the genera Geodermatophilus, Blastococcus, Frankia, Sporichthya, Acidothermus and Microsphaera, that it is proposed that it be placed in a novel genus, Quadrisphaera, as Quadrisphaera granulorum gen. nov., sp. nov. The type strain is AG019(T) (=ATCC BAA-1104(T)=DSM 44889(T)).

  12. Peptoniphilus methioninivorax sp. nov., A Novel Gram-Positive Anaerobic Coccus Isolated from Retail Ground Beef

    USDA-ARS?s Scientific Manuscript database

    Strain NRRL B-23883 was isolated from retail ground beef as part of a study on the genetic diversity of Clostridium perfringens. The strain was found to be a strictly anaerobic, gram-type positive coccus that was able to utilize peptone as a sole carbon source. Subsequent to sequencing the 16S rib...

  13. Comparative In Vitro Activities of SMT19969, a New Antimicrobial Agent, against Clostridium difficile and 350 Gram-Positive and Gram-Negative Aerobic and Anaerobic Intestinal Flora Isolates

    PubMed Central

    Citron, Diane M.; Tyrrell, Kerin L.; Merriam, C. Vreni

    2013-01-01

    The comparative in vitro activity of SMT19969, a novel, narrow-spectrum, nonabsorbable agent, was studied against 50 ribotype-defined Clostridium difficile strains, 174 Gram-positive and 136 Gram-negative intestinal anaerobes, and 40 Gram-positive aerobes. SMT19969 was one dilution more active against C. difficile isolates (MIC range, 0.125 to 0.5 μg/ml; MIC90, 0.25 μg/ml), including ribotype 027 strains, than fidaxomicin (range, 0.06 to 1 μg/ml; MIC90, 0.5 μg/ml) and two to six dilutions lower than either vancomycin or metronidazole. SMT19969 and fidaxomicin were generally less active against Gram-negative anaerobes, especially the Bacteroides fragilis group species, than vancomycin and metronidazole, suggesting that SMT19969 has a lesser impact on the normal intestinal microbiota that maintain colonization resistance. SMT19969 showed limited activity against other Gram-positive anaerobes, including Bifidobacteria species, Eggerthella lenta, Finegoldia magna, and Peptostreptococcus anaerobius, with MIC90s of >512, >512, 64, and 64 μg/ml, respectively. Clostridium species showed various levels of susceptibility, with C. innocuum being susceptible (MIC90, 1 μg/ml) and C. ramosum and C. perfringens being nonsusceptible (MIC90, >512 μg/ml). Activity against Lactobacillus spp. (range, 0.06 to >512 μg/ml; MIC90, >512 μg/ml) was comparable to that of fidaxomicin and varied by species and strain. Gram-positive aerobic cocci (Staphylococcus aureus, Enterococcus faecalis, E. faecium, and streptococci) showed high SMT19969 MIC90 values (128 to >512 μg/ml). PMID:23877700

  14. In vitro activity of Oritavancin against gram-positive pathogens isolated in Canadian hospital laboratories from 2011 to 2015.

    PubMed

    Karlowsky, James A; Walkty, Andrew J; Baxter, Melanie R; Arhin, Francis F; Moeck, Gregory; Adam, Heather J; Zhanel, George G

    2017-04-01

    Gram-positive bacterial pathogens isolated from patient specimens submitted to 15 Canadian hospital laboratories from 2011 to 2015 were tested in the coordinating laboratory for susceptibility to oritavancin and comparative antimicrobial agents using the Clinical and Laboratory Standards Institute M07-A10 (2015) broth microdilution method. Oritavancin's in vitro activity was equivalent to, or more potent than, vancomycin, daptomycin, linezolid, and tigecycline against methicillin-susceptible Staphylococcus aureus (n=2680; oritavancin MIC90, 0.12μg/mL; 99.9% oritavancin-susceptible), methicillin-resistant S. aureus (n=728; oritavancin MIC90, 0.12μg/mL; 99.7% oritavancin-susceptible), Streptococcus pyogenes (n=218; oritavancin MIC90, 0.25μg/mL; 100% oritavancin-susceptible), Streptococcus agalactiae (n=269; oritavancin MIC90, 0.12μg/mL; 100% oritavancin-susceptible), and vancomycin-susceptible Enterococcus faecalis (n=508; oritavancin MIC90, 0.06μg/mL; 100% oritavancin-susceptible). Oritavancin, dalbavancin, and telavancin demonstrated equivalent in vitro activities (MIC90, μg/mL) against 602 isolates of MSSA (0.06, 0.06, 0.06, respectively) and 144 isolates of MRSA (0.12, 0.06, 0.06, respectively) collected in 2015.

  15. Usefulness of the MicroSeq 500 16S rDNA bacterial identification system for identification of anaerobic Gram positive bacilli isolated from blood cultures

    PubMed Central

    Lau, S K P; Ng, K H L; Woo, P C Y; Yip, K‐t; Fung, A M Y; Woo, G K S; Chan, K‐m; Que, T‐l

    2006-01-01

    Using full 16S ribosomal RNA (rRNA) gene sequencing as the gold standard, 20 non‐duplicating anaerobic Gram positive bacilli isolated from blood cultures were analysed by the MicroSeq 500 16S rDNA bacterial identification system. The MicroSeq system successfully identified 13 of the 20 isolates. Four and three isolates were misidentified at the genus and species level, respectively. Although the MicroSeq 500 16S rDNA bacterial identification system is better than three commercially available identification systems also evaluated, its database needs to be expanded for accurate identification of anaerobic Gram positive bacilli. PMID:16443743

  16. Microcella putealis gen. nov., sp. nov., a gram-positive alkaliphilic bacterium isolated from a nonsaline alkaline groundwater.

    PubMed

    Tiago, Igor; Pires, Carlos; Mendes, Vítor; Morais, Paula V; da Costa, Milton; Veríssimo, António

    2005-08-01

    Three Gram-positive bacteria designated CV-2T, CV-40 and AC-30 were isolated from a highly alkaline groundwater environment (pH 11.4). These organisms formed very small rod-shaped cells, are aerobic, non-spore-forming, catalase-positive, oxidase-negative, with an optimum growth temperature of 35 degrees C and optimum pH value of growth between 8.5 and 9.0. The strains possessed a novel B-type cell-wall peptidoglycan structure with lysine as the diamino acid; the major respiratory quinones were menaquinone 12 (MK12) and MK13. The G + C content of DNA was between 67.1 and 70.7 mol%. The phylogenetic analyses of the sequences of the 16S rRNA genes reveled that they formed a deep branch within the family Microbacteriaceae, with the highest similarity of approximately 95.6% with members of the genera Agreia, Agrococcus, Cryobacterium, Clavibacter, Frigoribacterium, Leifsonia, Mycetocola, Rhodoglobus, Salinibacterium and Subtercola. Based on the phylogenetic analyses and distinct phenotypic characteristics, we are of the opinion that strains CV-2T, CV-40 and AC-30, represent a new species of a novel genus within the family Microbacteriaceae for which we propose the name Microcella putealis gen. nov., sp. nov.

  17. Comparative in vitro activity of gemifloxacin against gram-positive and gram-negative clinical isolates in Argentina.

    PubMed

    Lopez, H; Stepanik, D; Vilches, V; Scarano, S; Sarachian, B; Mikaelian, G; Finlay, J; Sucari, A

    2001-08-01

    The in vitro activity of gemifloxacin against 1,000 clinical isolates of 147 Streptococcus pneumoniae (115, penicilin susceptible; 26, intermediate penicillin-resistant and 6, penicillin-resistant), 127 Hemophilus influenzae (109, beta lactamasa non-producer; 18, beta lactamase producers), 95 Streptococcus pyogenes (6, azytromycin-resistant), 84 Moraxella catarrhalis (79, beta lactamase producers), 110 Staphilococcus aureus (89, methicillin-susceptible; 21, methicilin-resistant), 98 Eenterococcus faecalis and 339 Enterobacteriacea, (recovered from patients with respiratory tract infection; skin and soft tissue infection and urinary tract infection), was compared with the activities of four fluorquinolones and five other antimicrobial agents. Of the quinolones tested, gemifloxacin was the most potent against Streptococcus pneumoniae, including penicillin intermediate and resistant strains. Mic(90) values obtained for gemifloxacin, ciprofloxacin, ofloxacin, levofloxacin and trvafloxacin were 0.03, 2, 2, 1 and 0.25 mg/L respectively. Gemifloxacin was 16 fold more potent than ciprofloxacin against methicillin-susceptible Staphylococcus aureus and 32 fold more potent than ciprofloxacin against Streptococcus pyogenes. When tested against Hemophilus influenzae, Moraxella catarrhalis and Enterobacteriaceae, all the quinolones showed similar activity. Our results demonstrate that gemifloxacin has similar activity than the other quinolones tested against Gram-negative organisms and is considerably more potent against Gram-positive organisms.

  18. In vitro activity of tigecycline and comparators against Gram-positive and Gram-negative isolates collected from the Middle East and Africa between 2004 and 2011.

    PubMed

    Kanj, Souha S; Whitelaw, Andrew; Dowzicky, Michael J

    2014-02-01

    The Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) was established in 2004 to monitor longitudinal changes in bacterial susceptibility to numerous antimicrobial agents, specifically tigecycline. In this study, susceptibility among Gram-positive and Gram-negative isolates between 2004 and 2011 from the Middle East and Africa was examined. Antimicrobial susceptibilities were determined using Clinical and Laboratory Standards Institute (CLSI) interpretive criteria, and minimum inhibitory concentrations (MICs) were determined by broth microdilution methods. US Food and Drug Administration (FDA)-approved breakpoints were used for tigecycline. In total, 2967 Gram-positive and 6322 Gram-negative isolates were examined from 33 participating centres. All Staphylococcus aureus isolates, including meticillin-resistant S. aureus, were susceptible to tigecycline, linezolid and vancomycin. Vancomycin, linezolid, tigecycline and levofloxacin were highly active (>97.6% susceptibility) against Streptococcus pneumoniae, including penicillin-non-susceptible strains. All Enterococcus faecium isolates were susceptible to tigecycline and linezolid, including 32 vancomycin-resistant isolates. Extended-spectrum β-lactamases were produced by 16.6% of Escherichia coli and 32.9% of Klebsiella pneumoniae. More than 95% of E. coli and Enterobacter spp. were susceptible to amikacin, tigecycline, imipenem and meropenem. The most active agents against Pseudomonas aeruginosa and Acinetobacter baumannii were amikacin (88.0% susceptible) and minocycline (64.2% susceptible), respectively; the MIC90 (MIC required to inhibit 90% of the isolates) of tigecycline against A. baumannii was low at 2mg/L. Tigecycline and carbapenem agents were highly active against most Gram-negative pathogens. Tigecycline, linezolid and vancomycin showed good activity against most Gram-positive pathogens from the Middle East and Africa.

  19. Antimicrobial susceptibility trends among gram-positive and -negative clinical isolates collected between 2005 and 2012 in Mexico: results from the Tigecycline Evaluation and Surveillance Trial.

    PubMed

    Morfin-Otero, Rayo; Noriega, Eduardo Rodriguez; Dowzicky, Michael J

    2015-12-15

    The Tigecycline Evaluation and Surveillance Trial (T.E.S.T) is a global antimicrobial surveillance study of both gram-positive and gram-negative organisms. This report presents data on antimicrobial susceptibility among organisms collected in Mexico between 2005 and 2012 as part of T.E.S.T., and compares rates between 2005-2007 and 2008-2012. Each center in Mexico submitted at least 200 isolates per collection year; including 65 gram-positive isolates and 135 gram-negative isolates. Minimum inhibitory concentrations (MICs) were determined using Clinical Laboratory Standards Institute (CLSI) broth microdilution methodology and antimicrobial susceptibility was established using the 2013 CLSI-approved breakpoints. For tigecycline US Food and Drug Administration (FDA) breakpoints were applied. Isolates of E. coli and K. pneumoniae with a MIC for ceftriaxone of >1 mg/L were screened for ESBL production using the phenotypic confirmatory disk test according to CLSI guidelines. The rates of some key resistant phenotypes changed during this study: vancomycin resistance among Enterococcus faecium decreased from 28.6 % in 2005-2007 to 19.1 % in 2008-2012, while β-lactamase production among Haemophilus influenzae decreased from 37.6 to 18.9 %. Conversely, methicillin-resistant Staphylococcus aureus increased from 38.1 to 47.9 %, meropenem-resistant Acinetobacter spp. increased from 17.7 to 33.0 % and multidrug-resistant Acinetobacter spp. increased from 25.6 to 49.7 %. The prevalence of other resistant pathogens was stable over the study period, including extended-spectrum β-lactamase-positive Escherichia coli (39.0 %) and Klebsiella pneumoniae (25.0 %). The activity of tigecycline was maintained across the study years with MIC90s of ≤2 mg/L against Enterococcus spp., S. aureus, Streptococcus agalactiae, Streptococcus pneumoniae, Enterobacter spp., E. coli, K. pneumoniae, Klebsiella oxytoca, Serratia marcescens, H. influenzae, and Acinetobacter spp. All gram-positive

  20. Salirhabdus euzebyi gen. nov., sp. nov., a Gram-positive, halotolerant bacterium isolated from a sea salt evaporation pond.

    PubMed

    Albuquerque, Luciana; Tiago, Igor; Rainey, Fred A; Taborda, Marco; Nobre, M Fernanda; Veríssimo, António; da Costa, Milton S

    2007-07-01

    A low-G+C, Gram-positive bacterium, designated CVS-14(T), was recovered from a sea salt evaporation pond on the island of Sal in the Cape Verde Archipelago. This organism was catalase- and oxidase-positive. Cells were motile, spore-forming aerobic rods, with an optimum growth temperature of about 35-40 degrees C and optimum pH between 7.0 and 8.5. Optimal growth occurred in media containing 4-6 % (w/v) NaCl, although the organism was able to grow in medium without added NaCl and in medium containing 16 % NaCl. The cell-wall peptidoglycan was of A1 gamma type and the major respiratory quinone was menaquinone 7 (MK-7). Major fatty acids were iso-15 : 0, anteiso-15 : 0, iso-17 : 0 and anteiso-17 : 0. The DNA G+C content was 37.0 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain CVS-14(T) formed a distinct new branch within the radiation of the moderately halophilic bacilli group, forming a separate lineage from species of the genera Salinibacillus, Paucisalibacillus, Oceanobacillus, Lentibacillus and Virgibacillus. Strain CVS-14(T) showed 16S rRNA gene pairwise similarity values of approximately 95 % with species of the genus Salinibacillus. On the basis of morphological, physiological, chemotaxonomic and phylogenetic characteristics, strain CVS-14(T) is considered to represent a novel species in a new genus, for which the name Salirhabdus euzebyi gen. nov., sp. nov. is proposed. The type strain is CVS-14(T) (=LMG 22839(T)=CIP 108577(T)).

  1. Structure analysis of a class II transposon encoding the mercury resistance of the Gram-positive Bacterium bacillus megaterium MB1, a strain isolated from minamata bay, Japan.

    PubMed

    Huang, C C; Narita, M; Yamagata, T; Itoh, Y; Endo, G

    1999-07-08

    A unique transposon was found in the chromosome of Bacillus megaterium MB1, a Gram-positive bacterium isolated from mercury-polluted sediments of Minamata Bay, Japan. The transposon region of a 14.5kb DNA fragment was amplified by PCR using a single PCR primer designed from the nucleotide sequence of an inverted repeat of class II transposons. The molecular analysis revealed that the PCR-amplified DNA fragment encodes a transposition module similar to that of Tn21. The transposon also encodes a broad-spectrum mercury resistance region having a restriction endonuclease map identical to that of Bacillus cereus RC607, a strain isolated from Boston Harbor, USA. The result of a phylogenetic analysis of the amino acid sequence of putative resolvase of the transposon showed that the transposon is phylogenetically closer to the transposons of Gram-positive bacteria than those of Gram-negative bacteria. Besides the transposition module and mer operon, the transposon encodes a mobile genetic element of bacterial group II introns between the resolvase gene and mer operon. The intron, however, does not intervene in any exon gene. The discovery of this newly found combination of the complex mobile elements may offer a clue to understanding the horizontal dissemination of broad-spectrum mercury resistance among microbes.

  2. Emergence of Carbapenem resistant Gram negative and vancomycin resistant Gram positive organisms in bacteremic isolates of febrile neutropenic patients: A descriptive study

    PubMed Central

    Irfan, Seema; Idrees, Faiza; Mehraj, Vikram; Habib, Faizah; Adil, Salman; Hasan, Rumina

    2008-01-01

    Background This study was conducted to evaluate drug resistance amongst bacteremic isolates of febrile neutropenic patients with particular emphasis on emergence of carbapenem resistant Gram negative bacteria and vancomycin resistant Enterococcus species. Methods A descriptive study was performed by reviewing the blood culture reports from febrile neutropenic patients during the two study periods i.e., 1999–00 and 2001–06. Blood cultures were performed using BACTEC 9240 automated system. Isolates were identified and antibiotic sensitivities were done using standard microbiological procedures. Results Seven twenty six febrile neutropenic patients were admitted during the study period. A total of 5840 blood cultures were received, off these 1048 (18%) were culture positive. Amongst these, 557 (53%) grew Gram positive bacteria, 442 (42%) grew Gram negative bacteria, 43 (4%) fungi and 6 (1%) anaerobes. Sixty (5.7%) out of 1048 positive blood cultures were polymicrobial. In the Gram negative bacteria, Enterobacteriaceae was the predominant group; E. coli was the most frequently isolated organism in both study periods. Amongst non- Enterobacteriaceae group, Pseudomonas aeruginosa was the commonest organism isolated during first study period followed by Acinetobacter spp. However, during the second period Acinetobacter species was the most frequent pathogen. Enterobacteriaceae group showed higher statistically significant resistance in the second study period against ceftriaxone, quinolone and piperacillin/tazobactam, whilst no resistance observed against imipenem/meropenem. The susceptibility pattern of Acinetobacter species shifted from sensitive to highly resistant one with significant p values against ceftriaxone, quinolone, piperacillin/tazobactam and imipenem/meropenem. Amongst Gram positive bacteria, MRSA isolation rate remained static, vancomycin resistant Enterococcus species emerged in second study period while no Staphylococcus species resistant to

  3. Antimicrobial susceptibility testing of Gram-positive and -negative bacterial isolates directly from spiked blood culture media with Raman spectroscopy.

    PubMed

    Dekter, H E; Orelio, C C; Morsink, M C; Tektas, S; Vis, B; Te Witt, R; van Leeuwen, W B

    2017-01-01

    Patients suffering from bacterial bloodstream infections have an increased risk of developing systematic inflammatory response syndrome (SIRS), which can result in rapid deterioration of the patients' health. Diagnostic methods for bacterial identification and antimicrobial susceptibility tests are time-consuming. The aim of this study was to investigate whether Raman spectroscopy would be able to rapidly provide an antimicrobial susceptibility profile from bacteria isolated directly from positive blood cultures. First, bacterial strains (n = 133) were inoculated in tryptic soy broth and incubated in the presence or absence of antibiotics for 5 h. Antimicrobial susceptibility profiles were analyzed by Raman spectroscopy. Subsequently, a selection of strains was isolated from blood cultures and analyzed similarly. VITEK®2 technology and broth dilution were used as the reference methods. Raman spectra from 67 antibiotic-susceptible strains showed discriminatory spectra in the absence or at low concentrations of antibiotics as compared to high antibiotic concentrations. For 66 antibiotic-resistant strains, no antimicrobial effect was observed on the bacterial Raman spectra. Full concordance with VITEK®2 data and broth dilution was obtained for the antibiotic-susceptible strains, 68 % and 98 %, respectively, for the resistant strains. Discriminative antimicrobial susceptibility testing (AST) profiles were obtained for all bacterial strains isolated from blood cultures, resulting in full concordance with the VITEK®2 data. It can be concluded that Raman spectroscopy is able to detect the antimicrobial susceptibility of bacterial species isolated from a positive blood culture bottle within 5 h. Although Raman spectroscopy is cheap and rapid, further optimization is required, to fulfill a great promise for future AST profiling technology development.

  4. Isolation and purification of enterocin E-760 with broad antimicrobial activity against gram-positive and gram-negative bacteria.

    PubMed

    Line, J E; Svetoch, E A; Eruslanov, B V; Perelygin, V V; Mitsevich, E V; Mitsevich, I P; Levchuk, V P; Svetoch, O E; Seal, B S; Siragusa, G R; Stern, N J

    2008-03-01

    Strain NRRL B-30745, isolated from chicken ceca and identified as Enterococcus durans, Enterococcus faecium, or Enterococcus hirae, was initially identified as antagonistic to Campylobacter jejuni. The isolate produced a 5,362-Da bacteriocin (enterocin) that inhibits the growth of Salmonella enterica serovar Enteritidis, S. enterica serovar Choleraesuis, S. enterica serovar Typhimurium, S. enterica serovar Gallinarum, Escherichia coli O157:H7, Yersinia enterocolitica, Citrobacter freundii, Klebsiella pneumoniae, Shigella dysenteriae, Pseudomonas aeruginosa, Proteus mirabilis, Morganella morganii, Staphylococcus aureus, Staphylococcus epidermidis, Listeria monocytogenes, Campylobacter jejuni, and 20 other Campylobacter species isolates. The enterocin, E-760, was isolated and purified by cation-exchange and hydrophobic-interaction chromatographies. The proteinaceous nature of purified enterocin E-760 was demonstrated upon treatment with various proteolytic enzymes. Specifically, the antimicrobial peptide was found to be sensitive to beta-chymotrypsin, proteinase K, and papain, while it was resistant to lysozyme and lipase. The enterocin demonstrated thermostability by retaining activity after 5 min at 100 degrees C and was stable at pH values between 5.0 and 8.7. However, activity was lost below pH 3.0 and above pH 9.5. Administration of enterocin E-760-treated feed significantly (P < 0.05) reduced the colonization of young broiler chicks experimentally challenged and colonized with two strains of C. jejuni by more than 8 log(10) CFU. Enterocin E-760 also significantly (P < 0.05) reduced the colonization of naturally acquired Campylobacter species in market age broiler chickens when administered in treated feed 4 days prior to analysis.

  5. [Interpretative reading of the antibiogram in gram-positive cocci].

    PubMed

    Torres, Carmen

    2002-01-01

    Resistance to methicillin in Staphylococcus is related to expression of the gene mecA, and implies resistance to all beta-lactams. Breakpoints for interpretation of this mechanism differ in S. aureus and in coagulase-negative species. In relation to macrolides-lincosamides-streptograminsB, the most frequent mechanism among resistant strains is expression of methylases (erm genes). Topoisomerase changes caused by point mutations and expression of the efflux pump NorA determine resistance to quinolones, but there are great differences on the activity of different compounds, which makes interpretative reading difficult. Strains of S. aureus with intermediate susceptibility to glycopeptides (GISA strains) have been recently described. In Spain, there is a high percentage of S. pneumoniae strains intermediate or resistant to penicillin, and a low percentage of strains intermediate or resistant to third generation cephalosporins, because of mutations in genes encoding penicillin-binding proteins. The most frequent phenotype of resistance to macrolides in this species is caused by methylase production. Resistance to quinolones is still uncommon, and is related to the mechanisms previously indicated for Staphylococcus, but clinical interpretation of the antibiograma for this organism is even more complex. No strains of S. pyogenes resistant to penicillin have yet been described. In Spain the most common phenotype of resistance to macrolides in S. pyogenes is determined by efflux pumps (mef genes), affecting 14- and 15-membered macrolides. E. faecalis is usually susceptible to ampicillin, in contrast to E. faecium. Enterococci show intrinsic resistance to aminoglycosides, but still remain susceptible to the combination of these antimicrobials and cell-wall active agents. Strains expressing different aminoglycoside-modifying enzymes became resistant to the combination. Glycopeptide-resistant strains of enterococci are uncommon in our country, but several genotypes, of which vanA is the most relevant from a clinical point of view, have been described in other regions.

  6. Production of two bacteriocins in various growth conditions produced by gram-positive bacteria isolated from chicken cecum.

    PubMed

    Wang, Qiuju; Cui, Yizhe; Wang, Wenmei; Xu, Jili; Xu, Li

    2012-01-01

    Lactobacillus plantarum CLP29 and Enterococcus faecium CLE34 isolated from the cecal contents of young broiler chicks were identified based on physiological and biochemical characteristics, and identification was confirmed by 16S rRNA sequencing. Both bacteria showed a broad range of inhibitory action against bacteria such as Salmonella and Escherichia coli and produced two peptides, plantaricin CLP29 and enterocin CLE34. Treatment with proteinase K, trypase, or benase resulted in the loss of activity of the two peptides, confirming their proteinaceous nature. The highest activity levels for both bacteria were recorded in de Man - Rogosa - Sharpe agar at pH 5.0, 6.0, and 7.0, at 37 °C. Carbon and nitrogen sources affected the antibacterial activities of the two bacteriocins in different combinations, which suggested that the antibacterial abilities of different bacteriocins produced in nutrient sources were various.

  7. In vitro activity of tedizolid against gram-positive bacteria in patients with skin and skin structure infections and hospital-acquired pneumonia: a Korean multicenter study.

    PubMed

    Lee, Yangsoon; Hong, Sung Kuk; Choi, Sunghak; Im, Weonbin; Yong, Dongeun; Lee, Kyungwon

    2015-09-01

    We compared the activities of tedizolid to those of linezolid and other commonly used antimicrobial agents against gram-positive cocci recovered from patients with skin and skin structure infections (SSSIs) and hospital-acquired pneumonia (HAP) in Korean hospitals. Gram-positive isolates were collected from 356 patients with SSSIs and 144 patients with HAP at eight hospitals in Korea from 2011 to 2014. SSSIs included impetigo, cellulitis, erysipelas, furuncles, abscesses, and infected burns. Antimicrobial susceptibility was tested by using the CLSI agar dilution method. All of the gram-positive isolates were inhibited by ≤1 μg/mL tedizolid. The minimum inhibitory concentration [MIC]₉₀ of tedizolid was 0.5 μg/mL for methicillin-resistant Staphylococcus aureus, which was 4-fold lower than that of linezolid. Tedizolid may become a useful option for the treatment of SSSIs and HAP caused by gram-positive bacteria.

  8. In vitro activity of ceftazidime, ceftaroline and aztreonam alone and in combination with avibactam against European Gram-negative and Gram-positive clinical isolates.

    PubMed

    Testa, Raymond; Cantón, Rafael; Giani, Tommaso; Morosini, María-Isabel; Nichols, Wright W; Seifert, Harald; Stefanik, Danuta; Rossolini, Gian Maria; Nordmann, Patrice

    2015-06-01

    Recent clinical isolates of key Gram-negative and Gram-positive bacteria were collected in 2012 from hospitalised patients in medical centres in four European countries (France, Germany, Italy and Spain) and were tested using standard broth microdilution methodology to assess the impact of 4 mg/L avibactam on the in vitro activities of ceftazidime, ceftaroline and aztreonam. Against Enterobacteriaceae, addition of avibactam significantly enhanced the level of activity of these antimicrobials. MIC(90) values (minimum inhibitory concentration that inhibits 90% of the isolates) of ceftazidime, ceftaroline and aztreonam for Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, Enterobacter aerogenes, Citrobacter freundii and Morganella morganii were reduced up to 128-fold or greater when combined with avibactam. A two-fold reduction in the MIC(90) of ceftazidime to 8 mg/L was noted in Pseudomonas aeruginosa isolates when combined with avibactam, whereas little effect of avibactam was noted on the MIC values of the test compounds when tested against Acinetobacter baumannii isolates. Avibactam had little effect on the excellent activity of ceftazidime, ceftaroline and aztreonam against Haemophilus influenzae. It had no impact on the in vitro activity of ceftazidime and ceftaroline against staphylococci and streptococci. This study demonstrates that addition of avibactam enhances the activities of ceftazidime, ceftaroline and aztreonam against Enterobacteriaceae and P. aeruginosa but not against A. baumannii.

  9. Antimicrobial resistance patterns of the gram-positive bacteria isolated from children with bloodstream infection in an Iranian referral Hospital: a 6-year study.

    PubMed

    Mamishi, Setareh; Pourakbari, Babak; Mahmoudi, Shima; Moradzadeh, Mina; Mahzari, Masoumeh; Ashtiani, Mohammad TaghiHaghi; Tanzifi, Parin

    2017-08-21

    Bloodstream infections (BSI) are considered as a serious cause of morbidity and mortality in pediatricschildren. The aim of this study was to depict report the common Gram-positive bacteria (GPB) responsible for bloodstream infections in children and determine their antimicrobial resistance patterns in Children Medical Center Hospital (CMC), ) Hospital, Tehran, Iran. This retrospective study was conducted within a six-year period (March 2011 to September 2016) for pediatric patients with BSI. Standard bacteriological methods were performed for identification of the bacteria. Antimicrobial susceptibility tests were evaluated by using the disk diffusion method according to the CLSI recommendations. Among 68233 blood cultures, 2325 2349 isolates were obtained which 59% of them (N=13691393) were GPB and 41% (n=956) were Gram-negative. The most common GPB isolates were Coagulase negative Staphylococcus (CoNS) (N= 609, 44%), followed by Staphylococcus aureus (N=319, 23%), Enterococcus spp.(. (N=139, 10%), Streptococcus pneumonia (N= 106, 8%), Streptococci viridans (N= 180, 13%) Micrococcus spp. (N=24, 1.7%) and Streptococcus group B (N= 16, 1%). The rate of methicillin resistance in Staphylococcus S. aureus and CoNS was 47% (N=116/246) and 91% (N=557/609), respectively. Isolates of S. pneumoniae showed high-level of resistance to Trimethoprimtrimethoprim/sulfamethoxazole (N=28/33, 85%) and erythromycin (N=59/91, 65%). S. viridans isolates and Micrococcus spp. were highly sensitive to linezolid (100%). All of the tested isolates of Streptococcus group B were sensitive to all of antibiotic were used in this study. Among Enterococcus spp., 52% (N=69/133) of them were resistant to vancomycin. Our results emphasize the importance of a valuable guide in identifying resistance trends and selecting appropriate antibiotic. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  10. New antibiotics against gram-positives: present and future indications.

    PubMed

    Morata, Laura; Mensa, Josep; Soriano, Alex

    2015-10-01

    Gram-positive cocci are the most frequent aetiology of community and nosocomially bacterial acquired infections. The prevalence of multidrug-resistant gram-positive bacteria is increasing and is associated with high morbidity and mortality. New antibiotics will be available in the European market during the next months. This revision is focused on lipoglycopeptides, new cephalosporins active against methicillin-resistant Staphylococcus aureus (MRSA) and the new oxazolidinone, tedizolid. The purpose of this review is to describe their in vitro activity, pharmacokinetic and pharmacodynamic characteristics, and experience from clinical trials. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Comparative evaluation of the Vitek-2 Compact and Phoenix systems for rapid identification and antibiotic susceptibility testing directly from blood cultures of Gram-negative and Gram-positive isolates.

    PubMed

    Gherardi, Giovanni; Angeletti, Silvia; Panitti, Miriam; Pompilio, Arianna; Di Bonaventura, Giovanni; Crea, Francesca; Avola, Alessandra; Fico, Laura; Palazzo, Carlo; Sapia, Genoveffa Francesca; Visaggio, Daniela; Dicuonzo, Giordano

    2012-01-01

    We performed a comparative evaluation of the Vitek-2 Compact and Phoenix systems for direct identification and antimicrobial susceptibility testing (AST) from positive blood culture bottles in comparison to the standard methods. Overall, 139 monomicrobial blood cultures, comprising 91 Gram-negative and 48 Gram-positive isolates, were studied. Altogether, 100% and 92.3% of the Gram-negative isolates and 75% and 43.75% of the Gram-positive isolates showed concordant identification between the direct and the standard methods with Vitek and Phoenix, respectively. AST categorical agreements of 98.7% and 99% in Gram-negative and of 96.2% and 99.5% in Gram-positive isolates with Vitek and Phoenix, respectively, were observed. In conclusion, direct inoculation procedures for Gram-negative isolates showed an excellent performance with both automated systems, while for identification of Gram-positive isolates they proved to be less reliable, although Vitek provided acceptable results. This approach contributes to reducing the turnaround time to result of blood cultures, with a positive impact on patient care.

  12. Differential regulation of polysaccharide-specific antibody responses to isolated polysaccharides, conjugate vaccines, and intact Gram-positive versus Gram-negative extracellular bacteria.

    PubMed

    Snapper, Clifford M

    2016-06-24

    Bacterial capsular polysaccharides are major virulence factors and are key targets in a number of licensed anti-bacterial vaccines. Their major characteristics are their large molecular weight and expression of repeating antigenic epitopes that mediate multivalent B cell receptor cross-linking. In addition, since the majority of these antigens cannot associate with MHC-II they fail to recruit CD4+ T cell help and are referred to as T cell-independent antigens. In this review I will discuss a series of studies from my laboratory that have underscored the importance of understanding polysaccharide-specific antibody responses within the context in which the PS is expressed (i.e. in isolation, as a component of conjugate vaccines, and expressed naturally by intact bacteria). We have shown that multivalent B cell receptor crosslinking, as mediated by polysaccharides, uniquely determines the qualitative response of the B cell to subsequent stimuli, but by itself is insufficient to induce antibody secretion or class switching. For these latter events to occur, second signals must act in concert with primary signals derived from the B cell receptor. The co-expression of polysaccharide and protein within intact bacteria promotes recruitment of CD4+ T cell help for the associated PS-specific IgG response, in contrast to isolated polysaccharides. Further, the particulate nature of extracellular bacteria confers properties to the polysaccharide-specific IgG response that makes it distinct immunologically from soluble conjugate vaccines. Finally, the underlying biochemical and/or structural differences that distinguish Gram-positive and Gram-negative bacteria appear to play critical roles in differentially regulating the associated polysaccharide-specific IgG responses to these groups of pathogens. These studies have a number of implications for the understanding and future design of polysaccharide-based vaccines. Published by Elsevier Ltd.

  13. [Antimicrobial spectrum of dalbavancin. Mechanism of action and in vitro activity against Gram-positive microorganisms].

    PubMed

    Cercenado, Emilia

    2017-01-01

    Because of the increase in bacterial resistance, there is a need for new antimicrobial agents. Dalbavancin is a semisynthetic glycopeptide that inhibits the late stages of bacterial cell wall synthesis in the same way as vancomycin, but in addition, its lipophilic side chain anchors dalbavancin to the cellular membrane and allows enhanced activity compared with that of vancomycin. Dalbavancin possesses a broad spectrum of in vitro activity against Gram-positive aerobic and anaerobic microorganisms, being 4-8 times more potent than vancomycin. The spectrum of dalbavancin includes staphylococci, enterococci, streptococci, and anaerobic Gram-positive cocci and bacilli. It is active against different species of multiresistant microorganisms, including methicillin-resistant Staphylococcus aureus and penicillin-resistant viridans streptococci and Streptococcus pneumoniae. Although it shows in vitro activity against Enterococcus spp., it is inactive against isolates expressing the VanA phenotype of vancomycin resistance. It also shows slow bactericidal activity against S. aureus, coagulase-negative staphylococci, and Streptococcus pyogenes. In general, the MIC90 (minimum inhibitory concentration 90%) against the majority of the microorganisms is 0.06mg/L and, more than 98% of the isolates that have been tested are inhibited at concentrations of ≤ 0.12mg/L. Dalbavancin is an interesting addition to the therapeutic armamentarium for the treatment of infections caused by Gram-positive microorganisms, including multidrug-resistant isolates.

  14. Enzymes produced by halotolerant spore-forming gram-positive bacterial strains isolated from a resting habitat (Restinga de Jurubatiba) in Rio de Janeiro, Brazil: focus on proteases.

    PubMed

    D Santos, Anderson Fragoso; Pacheco, Clarissa Almeida; Valle, Roberta D Santos; Seldin, Lucy; D Santos, André Luis Souza

    2014-12-01

    The screening for hydrolases-producing, halotolerant, and spore-forming gram-positive bacteria from the root, rhizosphere, and non-rhizosphere soil of Blutaparon portulacoides, a plant found in the Restinga de Jurubatiba located at the northern region of Rio de Janeiro State, Brazil, resulted in the isolation of 22 strains. These strains were identified as Halobacillus blutaparonensis (n = 2), Oceanobacillus picturae (n = 5), and Oceanobacillus iheyensis (n = 15), and all showed the ability to produce different extracellular enzymes. A total of 20 isolates (90.9 %) showed activity for protease, 5 (22.7 %) for phytase, 3 (13.6 %) for cellulase, and 2 (9.1 %) for amylase. Some bacterial strains were capable of producing three (13.6 %) or two (9.1 %) distinct hydrolytic enzymes. However, no bacterial strain with ability to produce esterase and DNase was observed. The isolate designated M9, belonging to the species H. blutaparonensis, was the best producer of protease and also yielded amylase and phytase. This strain was chosen for further studies regarding its protease activity. The M9 strain produced similar amounts of protease when grown either without or with different NaCl concentrations (from 0.5 to 10 %). A simple inspection of the cell-free culture supernatant by gelatin-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed the presence of three major alkaline proteases of 40, 50, and 70 kDa, which were fully inhibited by phenylmethylsulfonyl fluoride (PMSF) and tosyl-L-phenylalanine chloromethyl ketone (TPCK) (two classical serine protease inhibitors). The secreted proteases were detected in a wide range of temperature (from 4 to 45 °C) and their hydrolytic activities were stimulated by NaCl (up to 10 %). The serine proteases produced by the M9 strain cleaved gelatin, casein, albumin, and hemoglobin, however, in different extensions. Collectively, these results suggest the potential use of the M9 strain in biotechnological

  15. Characterization of a cryptic plasmid from a Greenland ice core Arthrobacter isolate and construction of a shuttle vector that replicates in psychrophilic high G+C Gram-positive recipients.

    PubMed

    Miteva, Vanya; Lantz, Sarah; Brenchley, Jean

    2008-05-01

    Over 60 Greenland glacial isolates were screened for plasmids and antibiotic resistance/sensitivity as the first step in establishing a genetic system. Sequence analysis of a small, cryptic, 1,950 bp plasmid, p54, from isolate GIC54, related to Arthrobacter agilis, showed a region similar to that found in theta replicating Rhodococcus plasmids. A 6,002 bp shuttle vector, pSVJ21, was constructed by ligating p54 and pUC18 and inserting a chloramphenicol acetyl transferase (CAT) cassette conferring chloramphenicol resistance. Candidate Gram-positive recipients were chosen among glacial isolates based on phylogenetic relatedness, relatively short doubling times at low temperatures, sensitivity to antibiotics, and absence of indigenous plasmids. We developed an electroporation protocol and transformed seven isolates related to members of the Arthrobacter, Microbacterium, Curtobacterium, and Rhodoglobus genera with pSVJ21. Plasmid stability was demonstrated by successive transformation into Escherichia coli and four Gram-positive isolates, growth without antibiotic, and plasmid re-isolation. This shuttle vector and our transformation protocol provide the basis for genetic experiments with different high G+C Gram-positive hosts to study cold adaptation and expression of cold-active enzymes at low temperatures.

  16. Postantibiotic effect of ceftaroline against gram-positive organisms.

    PubMed

    Pankuch, G A; Appelbaum, P C

    2009-10-01

    The postantibiotic effects (PAEs), postantibiotic sub-MIC effects (PA-SMEs), and sub-MIC effects (SMEs) of ceftaroline, a novel injectable cephalosporin, were determined for 15 gram-positive organisms. The pneumococcal, staphylococcal, and enterococcal PAEs were 0.8 to 1.8 h, 0.7 to 2.2 h, and 0.2 to 1.1 h, respectively. The corresponding PA-SMEs (0.4 times the MIC) were 2.5 to 6.7 h, 2.9 to >0.0 h, and 7.9 to >10.3 h, respectively. The PA-SMEs were longer than the PAEs, suggesting that sub-MIC levels extend the PAE of ceftaroline against gram-positive cocci.

  17. Isolation and Structural Elucidation of Brevibacillin, an Antimicrobial Lipopeptide from Brevibacillus laterosporus That Combats Drug-Resistant Gram-Positive Bacteria.

    PubMed

    Yang, Xu; Huang, En; Yuan, Chunhua; Zhang, Liwen; Yousef, Ahmed E

    2016-05-01

    A new environmental bacterial strain exhibited strong antimicrobial characteristics against methicillin-resistant Staphylococcus aureus, vancomycin-resistant strains of Enterococcus faecalis and Lactobacillus plantarum, and other Gram-positive bacteria. The producer strain, designated OSY-I1, was determined to be Brevibacillus laterosporusvia morphological, biochemical, and genetic analyses. The antimicrobial agent was extracted from cells of OSY-I1 with isopropanol, purified by high-performance liquid chromatography, and structurally analyzed using mass spectrometry (MS) and nuclear magnetic resonance (NMR). The MS and NMR results, taken together, uncovered a linear lipopeptide consisting of 13 amino acids and an N-terminal C6 fatty acid (FA) chain, 2-hydroxy-3-methylpentanoic acid. The lipopeptide (FA-Dhb-Leu-Orn-Ile-Ile-Val-Lys-Val-Val-Lys-Tyr-Leu-valinol, where Dhb is α,β-didehydrobutyric acid and valinol is 2-amino-3-methyl-1-butanol) has a molecular mass of 1,583.0794 Da and contains three modified amino acid residues: α,β-didehydrobutyric acid, ornithine, and valinol. The compound, designated brevibacillin, was determined to be a member of a cationic lipopeptide antibiotic family. In addition to its potency against drug-resistant bacteria, brevibacillin also exhibited low MICs (1 to 8 μg/ml) against selected foodborne pathogenic and spoilage bacteria, such as Listeria monocytogenes,Bacillus cereus, and Alicyclobacillus acidoterrestris Purified brevibacillin showed no sign of degradation when it was held at 80 °C for 60 min, and it retained at least 50% of its antimicrobial activity when it was held for 22 h under acidic or alkaline conditions. On the basis of these findings, brevibacillin is a potent antimicrobial lipopeptide which is potentially useful to combat drug-resistant bacterial pathogens and foodborne pathogenic and spoilage bacteria.

  18. Isolation and Structural Elucidation of Brevibacillin, an Antimicrobial Lipopeptide from Brevibacillus laterosporus That Combats Drug-Resistant Gram-Positive Bacteria

    PubMed Central

    Yang, Xu; Yuan, Chunhua; Zhang, Liwen

    2016-01-01

    A new environmental bacterial strain exhibited strong antimicrobial characteristics against methicillin-resistant Staphylococcus aureus, vancomycin-resistant strains of Enterococcus faecalis and Lactobacillus plantarum, and other Gram-positive bacteria. The producer strain, designated OSY-I1, was determined to be Brevibacillus laterosporus via morphological, biochemical, and genetic analyses. The antimicrobial agent was extracted from cells of OSY-I1 with isopropanol, purified by high-performance liquid chromatography, and structurally analyzed using mass spectrometry (MS) and nuclear magnetic resonance (NMR). The MS and NMR results, taken together, uncovered a linear lipopeptide consisting of 13 amino acids and an N-terminal C6 fatty acid (FA) chain, 2-hydroxy-3-methylpentanoic acid. The lipopeptide (FA-Dhb-Leu-Orn-Ile-Ile-Val-Lys-Val-Val-Lys-Tyr-Leu-valinol, where Dhb is α,β-didehydrobutyric acid and valinol is 2-amino-3-methyl-1-butanol) has a molecular mass of 1,583.0794 Da and contains three modified amino acid residues: α,β-didehydrobutyric acid, ornithine, and valinol. The compound, designated brevibacillin, was determined to be a member of a cationic lipopeptide antibiotic family. In addition to its potency against drug-resistant bacteria, brevibacillin also exhibited low MICs (1 to 8 μg/ml) against selected foodborne pathogenic and spoilage bacteria, such as Listeria monocytogenes, Bacillus cereus, and Alicyclobacillus acidoterrestris. Purified brevibacillin showed no sign of degradation when it was held at 80°C for 60 min, and it retained at least 50% of its antimicrobial activity when it was held for 22 h under acidic or alkaline conditions. On the basis of these findings, brevibacillin is a potent antimicrobial lipopeptide which is potentially useful to combat drug-resistant bacterial pathogens and foodborne pathogenic and spoilage bacteria. PMID:26921428

  19. The Ellis Island Effect: A novel mobile element in a multi-drug resistant Bacteroides fragilis clinical isolate includes a mosaic of resistance genes from Gram-positive bacteria.

    PubMed

    Husain, Fasahath; Veeranagouda, Yaligara; Boente, Renata; Tang, Kevin; Mulato, Gabriela; Wexler, Hannah M

    2014-01-01

    Objectives: Bacteroides fragilis, a Gram-negative anaerobic bacterium, is alternately a gut commensal or virulent pathogen and is an important reservoir for horizontal gene transfer (HGT) of bacterial resistance and virulence genes in the human gastrointestinal tract. We identified a unique conjugative transposon (CTn) in a multidrug resistant clinical isolate of B. fragilis (BF-HMW615); we named this element CTnHyb because it included a hybrid mosaic of foreign elements. This study reports the characterization of CTnHyb and discusses the potential impact on horizontal spread of resistance genes. Results: CTnHyb contains several efflux pump genes and several genes that confer or may confer antibiotic resistance to tetracycline, kanamycin, metronidazole and spectinomycin (truncated gene). CTnHyb also contains a mosaic of mobile elements from Gram-positive organisms. CTnHyb is easily transferred from BF-HMW615 (the original isolate) to BF638R (lab strain) and integrated into the BF638R chromosome. The "foreign" (from Gram-positive bacteria) nucleotide sequences within CTnHyb were > 99% preserved indicating that the gene acquisition from the Gram-positive bacteria was very recent. Conclusion: CTnHyb is a novel CTn residing in a multidrug resistant strain of B. fragilis. The global nature and wide phylogenetic reach of HGT means that any gene in any bacterium can potentially be mobilized. Understanding the mechanisms that drive the formation and transfer of these elements and, potentially, ways to limit the transfer are necessary to prevent a devastating spread of resistance elements.

  20. Nonsporing, anaerobic, gram-positive rods in saliva and the gingival crevice of humans.

    PubMed Central

    Sanyal, B; Russell, C

    1978-01-01

    Quantitative and qualitative examination of anaerobically isolated flora of the gingival crevice and saliva was carried out. It was found that half the organisms were anaerobes and that there were twice as many gram-positive organisms as there were gram-negative ones. Rods were predominant in the gingival crevice (60.5%) and cocci in saliva (69.1%). Of the total organisms, nonsporing, gram-positive anaerobic rods accounted for 24% in the gingival crevice and 9.7% in saliva. These organisms were characterized on the basis of the type of fatty acids produced from glucose and various biochemical reactions. They belonged to the following genera: Actinomyces, Propionibacterium, Arachnia, Lactobacillus, Eubacterium, and Bifidobacterium. Bifidobacteria were present only in saliva. Although members of the other genera were present both in the gingival crevice and saliva, there were considerable differences in the proportion of any particular organism (in relation to the total anaerobic viable count) between the two sites. The result of this study also indicates a greater than previously appreciated level of Propionibacterium and Arachnia in the human mouth. PMID:646354

  1. Transformation of gram positive bacteria by sonoporation

    DOEpatents

    Yang, Yunfeng; Li, Yongchao

    2014-03-11

    The present invention provides a sonoporation-based method that can be universally applied for delivery of compounds into Gram positive bacteria. Gram positive bacteria which can be transformed by sonoporation include, for example, Bacillus, Streptococcus, Acetobacterium, and Clostridium. Compounds which can be delivered into Gram positive bacteria via sonoporation include nucleic acids (DNA or RNA), proteins, lipids, carbohydrates, viruses, small organic and inorganic molecules, and nano-particles.

  2. Activities of Tedizolid and Linezolid Determined by the Reference Broth Microdilution Method against 3,032 Gram-Positive Bacterial Isolates Collected in Asia-Pacific, Eastern Europe, and Latin American Countries in 2014

    PubMed Central

    Pfaller, Michael A.; Flamm, Robert K.; Jones, Ronald N.; Farrell, David J.

    2016-01-01

    Tedizolid and linezolid in vitro activities against 3,032 Gram-positive pathogens collected in Asia-Pacific, Eastern European, and Latin American medical centers during 2014 were assessed. The isolates were tested for susceptibility by the current reference broth microdilution methods. Due to concern over the effect of MIC endpoint criteria on the results of testing the oxazolidinones tedizolid and linezolid, MIC endpoint values were read by two methods: (i) reading the MIC at the first well where the trailing began without regard for pinpoint trailing, according to CLSI M07-A10 and M100-S26 document instructions for reading linezolid (i.e., 80% inhibition of growth; these reads were designated tedizolid 80 and linezolid 80), and (ii) at 100% inhibition of growth (designated tedizolid 100 and linezolid 100). All Staphylococcus aureus, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus anginosus group, and Enterococcus faecalis isolates were inhibited at tedizolid 80 and 100 MIC values of 0.25 and 0.5, 0.25 and 0.25, 0.25 and 0.5, 0.12 and 0.25, and 0.5 and 1 μg/ml, respectively. Generally, MIC50 and MIC90 results for tedizolid 80 and linezolid 80 were one doubling dilution lower than those read at 100% inhibition. Tedizolid was 4- to 8-fold more potent than linezolid against all the isolates tested regardless of the MIC endpoint criterion used. Despite the differences in potency, >99.9% of isolates tested in this survey were susceptible to both linezolid and tedizolid using CLSI and EUCAST interpretive criteria. In conclusion, tedizolid demonstrated greater in vitro potency than linezolid against Gram-positive pathogens isolated from patients in medical centers across the Asia-Pacific region, Eastern Europe, and Latin America. PMID:27353270

  3. Isolation of insertion elements from gram-positive Brevibacterium, Corynebacterium and Rhodococcus strains using the Bacillus subtilis sacB gene as a positive selection marker.

    PubMed

    Jäger, W; Schäfer, A; Kalinowski, J; Pühler, A

    1995-02-01

    The sacB gene of Bacillus subtilis was successfully applied in various Arthrobacter, Brevibacterium, Corynebacterium and Rhodococcus strains for the isolation of transposable elements. Three different insertion sequence (IS) elements entrapped in sacB were isolated. The IS elements IS-Bl and IS-Cg isolated from Brevibacterium lactofermentum and Corynebacterium glutamicum, respectively, were found to be similar in size (1.45 kb) and generated target duplications of 8 bp. Their inverted repeats showed homology. In contrast, the IS element IS-Rf isolated from Rhodococcus fascians was only 1.3 kb long and generated a 3-bp target duplication. IS-Cg and IS-Rf were not restricted to their original host strains, and we also found strains harbouring more than one element.

  4. Antibacterial activity of Lactobacillus acidophilus strains isolated from honey marketed in Malaysia against selected multiple antibiotic resistant (MAR) Gram-positive bacteria.

    PubMed

    Aween, Mohamed Mustafa; Hassan, Zaiton; Muhialdin, Belal J; Eljamel, Yossra A; Al-Mabrok, Asma Saleh W; Lani, Mohd Nizam

    2012-07-01

    A total of 32 lactic acid bacteria (LAB) were isolated from 13 honey samples commercially marketed in Malaysia, 6 strains identified as Lactobacillus acidophilus by API CHL50. The isolates had antibacterial activities against multiple antibiotic resistant's Staphylococcus aureus (25 to 32 mm), Staphylococcus epidermis (14 to 22 mm) and Bacillus subtilis (12 to 19 mm) in the agar overlay method after 24 h incubation at 30 °C. The crude supernatant was heat stable at 90 °C and 121 °C for 1 h. Treatment with proteinase K and RNase II maintained the antimicrobial activity of all the supernatants except sample H006-A and H010-G. All the supernatants showed antimicrobial activities against target bacteria at pH 3 and pH 5 but not at pH 6 within 72 h incubation at 30 °C. S. aureus was not inhibited by sample H006-A isolated from Libyan honey and sample H008-D isolated from Malaysian honey at pH 5, compared to supernatants from other L. acidophilus isolates. The presence of different strains of L. acidophilus in honey obtained from different sources may contribute to the differences in the antimicrobial properties of honey.

  5. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance.

    PubMed

    Valle, Demetrio L; Cabrera, Esperanza C; Puzon, Juliana Janet M; Rivera, Windell L

    2016-01-01

    Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria.

  6. Antimicrobial Activities of Methanol, Ethanol and Supercritical CO2 Extracts of Philippine Piper betle L. on Clinical Isolates of Gram Positive and Gram Negative Bacteria with Transferable Multiple Drug Resistance

    PubMed Central

    Valle, Demetrio L.; Cabrera, Esperanza C.; Puzon, Juliana Janet M.; Rivera, Windell L.

    2016-01-01

    Piper betle L. has traditionally been used in alternative medicine in different countries for various therapeutic purposes, including as an anti-infective agent. However, studies reported in the literature are mainly on its activities on drug susceptible bacterial strains. This study determined the antimicrobial activities of its ethanol, methanol, and supercritical CO2 extracts on clinical isolates of multiple drug resistant bacteria which have been identified by the Infectious Disease Society of America as among the currently more challenging strains in clinical management. Assay methods included the standard disc diffusion method and the broth microdilution method for the determination of the minimum inhibitory concentration (MIC) and the minimum bactericidal concentrations (MBC) of the extracts for the test microorganisms. This study revealed the bactericidal activities of all the P. betle leaf crude extracts on methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), extended spectrum β-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, and metallo-β-lactamase-producing Pseudomonas aeruginosa and Acinetobacter baumannii, with minimum bactericidal concentrations that ranged from 19μg/ml to 1250 μg/ml. The extracts proved to be more potent against the Gram positive MRSA and VRE than for the Gram negative test bacteria. VRE isolates were more susceptible to all the extracts than the MRSA isolates. Generally, the ethanol extracts proved to be more potent than the methanol extracts and supercritical CO2 extracts as shown by their lower MICs for both the Gram positive and Gram negative MDRs. MTT cytotoxicity assay showed that the highest concentration (100 μg/ml) of P. betle ethanol extract tested was not toxic to normal human dermal fibroblasts (HDFn). Data from the study firmly established P. betle as an alternative source of anti-infectives against multiple drug resistant bacteria. PMID

  7. X-ray photoelectron spectroscopy analysis of whole cells and isolated cell walls of gram-positive bacteria: comparison with biochemical analysis.

    PubMed Central

    Dufrêne, Y F; van der Wal, A; Norde, W; Rouxhet, P G

    1997-01-01

    The surface chemical composition of whole cells and isolated cell walls of four coryneform bacteria and of a Bacillus brevis strain has been determined by X-ray photoelectron spectroscopy (XPS). The XPS data were converted into concentrations of model compounds: peptides, polysaccharides, and hydrocarbonlike compounds. The composition of the surface of B. brevis differed markedly from that of coryneforms: the peptide concentration was about twice higher in the former case, which is attributed to the presence of an S-layer at the cell surface; in contrast, the surface of coryneforms was rich in hydrocarbonlike compounds (about 40%), which was concomitant with a high water contact angle. The peptide surface concentration of the isolated cell walls of the five strains deduced from XPS data fitted well with the total peptide content determined by biochemical analysis, which supports the validity of XPS to determine the overall macromolecular composition of the bacterial cell surface. Compared to biochemical analysis of isolated cell walls, XPS analysis of whole cells provides information which concerns directly the cell surface (2- to 5-nm-thick layer) and is less subject to alteration via losses of cell wall constituents or contamination by intracellular compounds. PMID:9023179

  8. Antibiotics for gram-positive organisms.

    PubMed

    Pagan, F S

    1981-01-01

    Most infections due to Gram-positive organisms can be treated with quite a small number of antibiotics. Penicillin, cloxacillin, and erythromycin should be enough to cover 90 per cent of Gram-positive infections. The relatively narrow spectrum of these drugs should be the incentive to prescribers to use them selectively, together with adequate bacteriological investigation, in order to achieve effective treatment with a minimum of disturbance to the patient's normal bacterial flora and without any other harmful side effects.

  9. Naumannella halotolerans gen. nov., sp. nov., a Gram-positive coccus of the family Propionibacteriaceae isolated from a pharmaceutical clean room and from food.

    PubMed

    Rieser, Gernot; Scherer, Siegfried; Wenning, Mareike

    2012-12-01

    Four Gram-stain-positive, aerobic bacterial strains isolated from a pharmaceutical clean room (strain WS4616(T)), a dessert milk product (strain WS4617) and from raw milk (strains WS4623 and WS4624) were characterized using a polyphasic approach. Phylogenetic analyses based on 16S rRNA and recA gene sequences showed that they formed a distinct lineage within the family Propionibacteriaceae. Similarity values between 16S rRNA gene sequences of the four novel strains and the type species of all genera belonging to the family Propionibacteriaceae were 89.2-94.1%. The major cellular fatty acid was anteiso-C(15:0) and the major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. Respiratory quinones were MK-8(H(4)) and MK-9(H(4)). The cell-wall peptidoglycan of type A3γ contained ll-diaminopimelic acid, alanine, glycine and glutamic acid. The G+C content of the genomic DNA of strain WS4616(T) was 67.7 mol%. The whole-cell sugar pattern contained ribose, mannose, arabinose, glucose and galactose. On the basis of phenotypic and genetic data, strains WS4616(T), WS4617, WS4623 and WS4624 are classified as members of a novel species in a new genus of the family Propionibacteriaceae, for which the name Naumannella halotolerans gen. nov., sp. nov. is proposed. The type strain is WS4616(T) ( = DSM 24323(T) = LMG 26184(T)) and three additional strains are WS4617, WS4623 and WS4624.

  10. Relationship between results of in vitro susceptibility tests and outcomes following treatment with pirlimycin hydrochloride in cows with subclinical mastitis associated with gram-positive pathogens.

    PubMed

    Apparao, Dhananjay; Oliveira, Leane; Ruegg, Pamela L

    2009-06-01

    To determine the association between results of in vitro antimicrobial susceptibility tests and outcomes in cows that received intramammary treatment with pirlimycin hydrochloride for subclinical mastitis associated with gram-positive pathogens. Case-control study. 132 dairy cows (178 mammary glands with subclinical mastitis caused by 194 pathogen isolates). Cows with positive results for a California mastitis test (CMT) were assigned to receive 50 mg of pirlimycin via intramammary administration into each CMT-positive mammary gland every 24 hours for 2 consecutive days or no treatment. Duplicate milk samples were collected before treatment and approximately 21 days later. Target pathogens included coagulase-negative Staphylococcus spp (n = 118 isolates), Streptococcus spp (28), Staphylococcus aureus (7), and other gram-positive cocci (30). Antimicrobial susceptibilities were determined via broth microdilution. Overall treatment success rate was 66% (128/194) for both groups. In vitro resistance to pirlimycin ranged from 0% (0/7 isolates of S aureus) to 50% (13/26 isolates of other gram-positive cocci). For the treated group, 62 of 94 (66%) target pathogens were classified as treatment successes and 32 (34%) were classified as failures. Similarly for the control group, 66 of 100 (66%) target pathogens were classified as treatment successes, whereas 34 (34%) were classified as failures. Many target pathogens from cows with subclinical mastitis were eliminated without treatment, and treatment with pirlimycin did not improve the treatment success rate. Results of in vitro antimicrobial susceptibility tests were not useful as predictors of treatment success following intramammary treatment with pirlimycin.

  11. Evolving resistance among Gram-positive pathogens.

    PubMed

    Munita, Jose M; Bayer, Arnold S; Arias, Cesar A

    2015-09-15

    Antimicrobial therapy is a key component of modern medical practice and a cornerstone for the development of complex clinical interventions in critically ill patients. Unfortunately, the increasing problem of antimicrobial resistance is now recognized as a major public health threat jeopardizing the care of thousands of patients worldwide. Gram-positive pathogens exhibit an immense genetic repertoire to adapt and develop resistance to virtually all antimicrobials clinically available. As more molecules become available to treat resistant gram-positive infections, resistance emerges as an evolutionary response. Thus, antimicrobial resistance has to be envisaged as an evolving phenomenon that demands constant surveillance and continuous efforts to identify emerging mechanisms of resistance to optimize the use of antibiotics and create strategies to circumvent this problem. Here, we will provide a broad perspective on the clinical aspects of antibiotic resistance in relevant gram-positive pathogens with emphasis on the mechanistic strategies used by these organisms to avoid being killed by commonly used antimicrobial agents.

  12. Antibiotic resistance patterns of Gram-negative and Gram-positive strains isolated from inpatients with nosocomial infections in a tertiary hospital in Beijing, China from 2011 to 2014.

    PubMed

    Zhu, Xiaoyan; Tong, Aihua; Wang, Di; Sun, Huijie; Chen, Ling; Dong, Mei

    2016-06-27

    This study was to evaluate the resistance of antimicrobial agents against pathogens from inpatients with nosocomial infection collected in Beijing, China, during 2011-2014. Measurement of minimum inhibitory concentrations (MICs) was carried out using the broth microdilution method with the Clinical and Laboratory Standards Institute (CLSI) guidelines as the indicator. A total of 5442 Gram-negative and 806 Gram-positive isolates were collected in this study in 2011-2014. Two carbapenem-resistant strains appeared among Escherichia coli (E. coli), while imipenem-resistant isolates increased in proportion from 0% to 8.2% among Klebsiella pneumonia (K. pneumonia) during 4 year. Acinetobacter baumannii (A. baumannii) revealed severe antibacterial resistance to most antimicrobial agents. In contrast, a decreasing trend on resistance had been observed among Pseudomonas aeruginosa (P. aeruginosa) especially after 2012, range from 1.8% for co-trimoxazole to 13.5% for piperacillin. The resistance of Staphylococcus aureus (S. aureus) also had the lowest resistant to linezolid and vancomycin (0.1%). In summary, antimicrobial-resistant nosocomial pathogens have gradually increased from 2011 to 2014, so improved surveillance of hospital-acquired infections and effective infection-control measures may be the best way to solve the present problem.

  13. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, L.O.; Barbosa-Alleyne, M.D.F.

    1999-06-29

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

  14. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, L.O.; Barbosa-Alleyne, M.D.F.

    1996-01-09

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase. 2 figs.

  15. Ethanol production in gram-positive microbes

    DOEpatents

    Ingram, Lonnie O'Neal; Barbosa-Alleyne, Maria D. F.

    1999-01-01

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

  16. Ethanol production in Gram-positive microbes

    DOEpatents

    Ingram, Lonnie O'Neal; Barbosa-Alleyne, Maria D. F.

    1996-01-01

    The subject invention concerns the transformation of Gram-positive bacteria with heterologous genes which confer upon these microbes the ability to produce ethanol as a fermentation product. Specifically exemplified is the transformation of bacteria with genes, obtainable from Zymomonas mobilis, which encode pyruvate decarboxylase and alcohol dehydrogenase.

  17. alpha-1,4-D-glucan phosphorylase of gram-positive Corynebacterium callunae: isolation, biochemical properties and molecular shape of the enzyme from solution X-ray scattering.

    PubMed Central

    Weinhäusel, A; Griessler, R; Krebs, A; Zipper, P; Haltrich, D; Kulbe, K D; Nidetzky, B

    1997-01-01

    The alpha-1,4-D-glucan phosphorylase from gram-positive Corynebacterium callunae has been isolated and characterized. The enzyme is inducible approx. 2-fold by maltose, but remarkably not repressed by D-glucose. The phosphorylase is a homodimer with a stoichiometric content of the cofactor pyridoxal 5'-phosphate per 88-kDa protein subunit. The specificity constants (kcat/Km, glucan) in the directions of glucan synthesis and degradation are used for the classification of the enzyme as the first bacterial starch phosphorylase. A preference for large over small substrates is determined by variations in the apparent binding constants rather than catalytic-centre activities. The contribution of substrate chain length to binding energy is explained assuming two glucan binding sites in C. callunae phosphorylase: an oligosaccharide binding site composed of five subsites and a high-affinity polysaccharide site separated from the active site. A structural model of the molecular shape of the phosphorylase was obtained from small-angle solution X-ray scattering measurements. A flat, slightly elongated, ellipsoidal model with the three axes related to each other as 1:(0.87-0.95):0.43 showed scattering equivalence with the enzyme molecule. The model of C. callunae phosphorylase differs from the structurally well-characterized rabbit-muscle phosphorylase in size and axial dimensions. PMID:9307027

  18. Use of MALDI-TOF Mass Spectrometry for the Fast Identification of Gram-Positive Fish Pathogens

    PubMed Central

    Assis, Gabriella B. N.; Pereira, Felipe L.; Zegarra, Alexandra U.; Tavares, Guilherme C.; Leal, Carlos A.; Figueiredo, Henrique C. P.

    2017-01-01

    Gram-positive cocci, such as Streptococcus agalactiae, Lactococcus garvieae, Streptococcus iniae, and Streptococcus dysgalactiae subsp. dysgalactiae, are found throughout the world, particularly in outbreaks in farmed fish, and are thus associated with high economic losses, especially in the cultivation of Nile Tilapia. The aim of this study was to evaluate the efficacy of matrix-assisted laser desorption ionization (MALDI)-time of flight (TOF) mass spectrometry (MS) as an alternative for the diagnosis of these pathogens. One hundred and thirty-one isolates from Brazilian outbreaks assisted by the national authority were identified using a MALDI Biotyper from Bruker Daltonics. The results showed an agreement with respect to identification (Kappa = 1) between this technique and 16S ribosomal RNA gene sequencing for S. agalactiae and L. garvieae. However, for S. iniae and S. dysgalactiae subsp. dysgalactiae, perfect agreement was only achieved after the creation of a custom main spectra profile, as well as further comparisons with 16S ribosomal RNA and multilocus sequence analysis. MALDI-TOF MS was shown to be an efficient technology for the identification of these Gram-positive pathogens, yielding a quick and precise diagnosis. PMID:28848512

  19. Use of MALDI-TOF Mass Spectrometry for the Fast Identification of Gram-Positive Fish Pathogens.

    PubMed

    Assis, Gabriella B N; Pereira, Felipe L; Zegarra, Alexandra U; Tavares, Guilherme C; Leal, Carlos A; Figueiredo, Henrique C P

    2017-01-01

    Gram-positive cocci, such as Streptococcus agalactiae, Lactococcus garvieae, Streptococcus iniae, and Streptococcus dysgalactiae subsp. dysgalactiae, are found throughout the world, particularly in outbreaks in farmed fish, and are thus associated with high economic losses, especially in the cultivation of Nile Tilapia. The aim of this study was to evaluate the efficacy of matrix-assisted laser desorption ionization (MALDI)-time of flight (TOF) mass spectrometry (MS) as an alternative for the diagnosis of these pathogens. One hundred and thirty-one isolates from Brazilian outbreaks assisted by the national authority were identified using a MALDI Biotyper from Bruker Daltonics. The results showed an agreement with respect to identification (Kappa = 1) between this technique and 16S ribosomal RNA gene sequencing for S. agalactiae and L. garvieae. However, for S. iniae and S. dysgalactiae subsp. dysgalactiae, perfect agreement was only achieved after the creation of a custom main spectra profile, as well as further comparisons with 16S ribosomal RNA and multilocus sequence analysis. MALDI-TOF MS was shown to be an efficient technology for the identification of these Gram-positive pathogens, yielding a quick and precise diagnosis.

  20. Antiadhesion agents against Gram-positive pathogens.

    PubMed

    Cascioferro, Stella; Cusimano, Maria Grazia; Schillaci, Domenico

    2014-01-01

    A fundamental step of Gram-positive pathogenesis is the bacterial adhesion to the host tissue involving interaction between bacterial surface molecules and host ligands. This review is focused on antivirulence compounds that target Gram-positive adhesins and on their potential development as therapeutic agents alternative or complementary to conventional antibiotics in the contrast of pathogens. In particular, compounds that target the sortase A, wall theicoic acid inhibitors, carbohydrates able to bind bacterial proteins and proteins capable of influencing the bacterial adhesion, were described. We further discuss the advantages and disadvantages of this strategy in the development of novel antimicrobials and the future perspective of this research field still at its first steps.

  1. Evolving Resistance Among Gram-positive Pathogens

    PubMed Central

    Munita, Jose M.; Bayer, Arnold S.; Arias, Cesar A.

    2015-01-01

    Antimicrobial therapy is a key component of modern medical practice and a cornerstone for the development of complex clinical interventions in critically ill patients. Unfortunately, the increasing problem of antimicrobial resistance is now recognized as a major public health threat jeopardizing the care of thousands of patients worldwide. Gram-positive pathogens exhibit an immense genetic repertoire to adapt and develop resistance to virtually all antimicrobials clinically available. As more molecules become available to treat resistant gram-positive infections, resistance emerges as an evolutionary response. Thus, antimicrobial resistance has to be envisaged as an evolving phenomenon that demands constant surveillance and continuous efforts to identify emerging mechanisms of resistance to optimize the use of antibiotics and create strategies to circumvent this problem. Here, we will provide a broad perspective on the clinical aspects of antibiotic resistance in relevant gram-positive pathogens with emphasis on the mechanistic strategies used by these organisms to avoid being killed by commonly used antimicrobial agents. PMID:26316558

  2. Virulence Plasmids of Nonsporulating Gram-Positive Pathogens

    PubMed Central

    Van Tyne, Daria; Gilmore, Michael S.

    2014-01-01

    SUMMARY Gram-positive bacteria are leading causes of many types of human infection, including pneumonia, skin and nasopharyngeal infections, as well as urinary tract and surgical wound infections among hospitalized patients. These infections have become particularly problematic because many of the species causing them have become highly resistant to antibiotics. The role of mobile genetic elements, such as plasmids, in the dissemination of antibiotic resistance among Gram-positive bacteria has been well studied; less well understood is the role of mobile elements in the evolution and spread of virulence traits among these pathogens. While these organisms are leading agents of infection, they are also prominent members of the human commensal ecology. It appears that these bacteria are able to take advantage of the intimate association between host and commensal, via virulence traits that exacerbate infection and cause disease. However, evolution into an obligate pathogen has not occurred, presumably because it would lead to rejection of pathogenic organisms from the host ecology. Instead, in organisms that exist as both commensal and pathogen, selection has favored the development of mechanisms for variability. As a result, many virulence traits are localized on mobile genetic elements, such as virulence plasmids and pathogenicity islands. Virulence traits may occur within a minority of isolates of a given species, but these minority populations have nonetheless emerged as a leading problem in infectious disease. This chapter reviews virulence plasmids in nonsporulating Gram-positive bacteria, and examines their contribution to disease pathogenesis. PMID:25544937

  3. Evaluation of a microarray-based assay for rapid identification of Gram-positive organisms and resistance markers in positive blood cultures.

    PubMed

    Samuel, Linoj P; Tibbetts, Robert J; Agotesku, Adam; Fey, Margaret; Hensley, Rhonda; Meier, Frederick A

    2013-04-01

    Rapid identification of pathogens directly from positive blood cultures can play a major role in reducing patient mortality rates. We evaluated the performance of the Verigene Gram-Positive Blood Culture (BC-GP) assay (Nanosphere Inc., Northbrook, IL) for detection of commonly isolated Gram-positive organisms as well as associated resistance markers from positive blood cultures. Positive blood cultures (VersaTREK; Trek Diagnostic Systems, Independence, OH) from 203 patients with Gram-positive organism infections were analyzed using the BC-GP assay within 12 h for the detection of 12 different organisms, including staphylococci, streptococci, and enterococci, as well as for the presence of 3 resistance markers (mecA, vanA, and vanB). Results were compared to those of routine laboratory methods for identification and susceptibility testing. For identification of organisms and detection of resistance markers in 178 monomicrobial positive blood cultures, the BC-GP assay showed 94% and 97% concordance, respectively, with routine methods. After 25 polymicrobial cultures were included, the results showed 92% and 96% agreement for identification and resistance markers, respectively, for a total of 203 positive cultures. In 6/25 polymicrobial cultures, at least 1 isolate was not detected. Concordance levels for detection of major pathogens such Staphylococcus aureus (n = 45) and enterococci (n = 19) were 98% and 95%, respectively. Agreement levels for detection of resistance markers such as mecA and vanA/B were 92% and 100%, respectively. The BC-GP assay is capable of providing rapid identification of Gram-positive cocci as well as detection of resistance markers directly from positive blood cultures at least 24 to 48 h earlier than conventional methods.

  4. Bacteriocins of gram-positive bacteria.

    PubMed Central

    Jack, R W; Tagg, J R; Ray, B

    1995-01-01

    In recent years, a group of antibacterial proteins produced by gram-positive bacteria have attracted great interest in their potential use as food preservatives and as antibacterial agents to combat certain infections due to gram-positive pathogenic bacteria. They are ribosomally synthesized peptides of 30 to less than 60 amino acids, with a narrow to wide antibacterial spectrum against gram-positive bacteria; the antibacterial property is heat stable, and a producer strain displays a degree of specific self-protection against its own antibacterial peptide. In many respects, these proteins are quite different from the colicins and other bacteriocins produced by gram-negative bacteria, yet customarily they also are grouped as bacteriocins. Although a large number of these bacteriocins (or bacteriocin-like inhibitory substances) have been reported, only a few have been studied in detail for their mode of action, amino acid sequence, genetic characteristics, and biosynthesis mechanisms. Nevertheless, in general, they appear to be translated as inactive prepeptides containing an N-terminal leader sequence and a C-terminal propeptide component. During posttranslational modifications, the leader peptide is removed. In addition, depending on the particular type, some amino acids in the propeptide components may undergo either dehydration and thioether ring formation to produce lanthionine and beta-methyl lanthionine (as in lantibiotics) or thio ester ring formation to form cystine (as in thiolbiotics). Some of these steps, as well as the translocation of the molecules through the cytoplasmic membrane and producer self-protection against the homologous bacteriocin, are mediated through specific proteins (enzymes). Limited genetic studies have shown that the structural gene for such a bacteriocin and the genes encoding proteins associated with immunity, translocation, and processing are present in a cluster in either a plasmid, the chromosome, or a transposon. Following

  5. Activity of retapamulin (SB-275833), a novel pleuromutilin, against selected resistant gram-positive cocci.

    PubMed

    Jones, Ronald N; Fritsche, Thomas R; Sader, Helio S; Ross, James E

    2006-07-01

    Retapamulin (SB-275833), the first pleuromutilin to be developed for human topical use, was tested against a selected population of staphylococci and beta-hemolytic streptococci. The MIC90 results for retapamulin were 0.12 microg/ml for Staphylococcus aureus and < or = 0.03 microg/ml for Streptococcus pyogenes; no cross-resistance was observed for organism subsets resistant to oxacillin, erythromycin, or mupirocin.

  6. Activity of Retapamulin (SB-275833), a Novel Pleuromutilin, against Selected Resistant Gram-Positive Cocci

    PubMed Central

    Jones, Ronald N.; Fritsche, Thomas R.; Sader, Helio S.; Ross, James E.

    2006-01-01

    Retapamulin (SB-275833), the first pleuromutilin to be developed for human topical use, was tested against a selected population of staphylococci and β-hemolytic streptococci. The MIC90 results for retapamulin were 0.12 μg/ml for Staphylococcus aureus and ≤0.03 μg/ml for Streptococcus pyogenes; no cross-resistance was observed for organism subsets resistant to oxacillin, erythromycin, or mupirocin. PMID:16801451

  7. Peptide conversations in Gram-positive bacteria.

    PubMed

    Monnet, Véronique; Juillard, Vincent; Gardan, Rozenn

    2016-05-01

    Within Gram-positive bacteria, the expression of target genes is controlled at the population level via signaling peptides, also known as pheromones. Pheromones control a wide range of functions, including competence, virulence, and others that remain unknown. Until now, their role in bacterial gene regulation has probably been underestimated; indeed, bacteria are able to produce, by ribosomal synthesis or surface protein degradation, an extraordinary variety of peptides which are released outside bacteria and among which, some are pheromones that mediate cell-to-cell communication. The review aims at giving an updated overview of these peptide-dependant communication pathways. More specifically, it follows the whole peptide circuit from the peptide production and secretion in the extracellular medium to its interaction with sensors at bacterial surface or re-import into the bacteria where it plays its regulation role. In recent years, as we have accumulated more knowledge about these systems, it has become apparent that they are more complex than they first appeared. For this reason, more research on peptide-dependant pathways is needed to develop new strategies for controlling functions of interest in Gram-positive bacteria. In particular, such research could lead to alternatives to the use of antibiotics against pathogenic bacteria. In perspective, the review identifies new research questions that emerge in this field and that have to be addressed.

  8. Antimicrobial Peptides Targeting Gram-Positive Bacteria

    PubMed Central

    Malanovic, Nermina; Lohner, Karl

    2016-01-01

    Antimicrobial peptides (AMPs) have remarkably different structures as well as biological activity profiles, whereupon most of these peptides are supposed to kill bacteria via membrane damage. In order to understand their molecular mechanism and target cell specificity for Gram-positive bacteria, it is essential to consider the architecture of their cell envelopes. Before AMPs can interact with the cytoplasmic membrane of Gram-positive bacteria, they have to traverse the cell wall composed of wall- and lipoteichoic acids and peptidoglycan. While interaction of AMPs with peptidoglycan might rather facilitate penetration, interaction with anionic teichoic acids may act as either a trap for AMPs or a ladder for a route to the cytoplasmic membrane. Interaction with the cytoplasmic membrane frequently leads to lipid segregation affecting membrane domain organization, which affects membrane permeability, inhibits cell division processes or leads to delocalization of essential peripheral membrane proteins. Further, precursors of cell wall components, especially the highly conserved lipid II, are directly targeted by AMPs. Thereby, the peptides do not inhibit peptidoglycan synthesis via binding to proteins like common antibiotics, but form a complex with the precursor molecule, which in addition can promote pore formation and membrane disruption. Thus, the multifaceted mode of actions will make AMPs superior to antibiotics that act only on one specific target. PMID:27657092

  9. Conjugation in Gram-Positive Bacteria.

    PubMed

    Goessweiner-Mohr, Nikolaus; Arends, Karsten; Keller, Walter; Grohmann, Elisabeth

    2014-08-01

    Conjugative transfer is the most important means of spreading antibiotic resistance and virulence factors among bacteria. The key vehicles of this horizontal gene transfer are a group of mobile genetic elements, termed conjugative plasmids. Conjugative plasmids contain as minimum instrumentation an origin of transfer (oriT), DNA-processing factors (a relaxase and accessory proteins), as well as proteins that constitute the trans-envelope transport channel, the so-called mating pair formation (Mpf) proteins. All these protein factors are encoded by one or more transfer (tra) operons that together form the DNA transport machinery, the Gram-positive type IV secretion system. However, multicellular Gram-positive bacteria belonging to the streptomycetes appear to have evolved another mechanism for conjugative plasmid spread reminiscent of the machinery involved in bacterial cell division and sporulation, which transports double-stranded DNA from donor to recipient cells. Here, we focus on the protein key players involved in the plasmid spread through the two different modes and present a new secondary structure homology-based classification system for type IV secretion protein families. Moreover, we discuss the relevance of conjugative plasmid transfer in the environment and summarize novel techniques to visualize and quantify conjugative transfer in situ.

  10. [Epidemiology of the infection by resistant Gram-positive microorganisms].

    PubMed

    Cercenado, E

    2016-09-01

    Resistance among Gram-positive microorganisms to classical and new antimicrobials is a therapeutic threat. In Spain, methicillin resistance among Staphylococcus aureus (25-30%) and coagulase-negative staphylococci (50-60%) seems to have stabilized in the last decade. Among enterococci, vancomycin resistance is less than 5%. Both linezolid and daptomycin, in general, show good activity against these microorganisms. However, the resistance rates of Staphylococcus epidermidis to linezolid (20.9%), and of Enterococcus faecium to daptomycin (10.5%) in isolates from intensive care units are a worrying.

  11. [GEIPC-SEIMC and GTEI-SEMICYUC recommendations for antibiotic treatment of gram positive coccal infections in the critical patient].

    PubMed

    Olaechea Astigarraga, P M; Garnacho Montero, J; Grau Cerrato, S; Rodríguez Colomo, O; Palomar Martínez, M; Zaragoza Crespo, R; Muñoz García-Paredes, P; Cerdá Cerdá, E; Alvarez Lerma, F

    2007-01-01

    In recent years, an increment of infections caused by gram-positive cocci has been documented in nosocomial and hospital-acquired infections. In diverse countries, a rapid development of resistance to common antibiotics against gram-positive cocci has been observed. This situation is exceptional in Spain but our country might be affected in the near future. New antimicrobials active against these multi-drug resistant pathogens are nowadays available. It is essential to improve our current knowledge about pharmacokinetic properties of traditional and new antimicrobials to maximize its effectiveness and to minimize toxicity. These issues are even more important in critically ill patients because inadequate empirical therapy is associated with therapeutic failure and a poor outcome. Experts representing two scientific societies (Grupo de estudio de Infecciones en el Paciente Critico de la SEIMC and Grupo de trabajo de Enfermedades Infecciosas de la SEMICYUC) have elaborated a consensus document based on the current scientific evidence to summarize recommendations for the treatment of serious infections caused by gram-positive cocci in critically ill patients.

  12. Tandem affinity purification vectors for use in gram positive bacteria.

    PubMed

    Yang, Xiao; Doherty, Geoff P; Lewis, Peter J

    2008-01-01

    Tandem affinity purification has become a valuable tool for the isolation of protein complexes. Here we describe the construction and use of a series of plasmid vectors for Gram positive bacteria. The vectors utilize the SPA tag as well as variants containing a 3C rather than the TEV protease site as 3C protease has been shown to work efficiently at the low temperatures (4 degrees C) used to isolate protein complexes. In addition, a further vector incorporates a GST moiety in place of the 3xFLAG of the SPA tag which provides an additional tagging option for situations where SPA binding may be inefficient. The vectors are all compatible with previously constructed fluorescent protein fusion vectors enabling construction of a suite of affinity and fluorescently tagged genes using a single PCR product.

  13. Classification of Bacteriocins from Gram-Positive Bacteria

    NASA Astrophysics Data System (ADS)

    Rea, Mary C.; Ross, R. Paul; Cotter, Paul D.; Hill, Colin

    Bacteriocins are ribosomally synthesised antimicrobial peptides produced by bacteria, including many Gram-positive species. The classification of bacteriocins from Gram-positive bacteria is complicated by their heterogeneity and thus, as the number of Gram-positive bacteriocins identified has continued to increase, classification schemes have had to continuously evolve. Here, we review the various classification approaches, both historical and current, their underlying scientific basis and their relative merit, and suggest a rational scheme given the state of the art.

  14. [Update of antimicrobial resistance in Gram-positive microorganisms].

    PubMed

    Cercenado, Emilia

    2010-12-01

    In the last few decades, resistance among Gram-positive microorganisms to classical antimicrobials as well as the emergence of resistance to new antimicrobials has been observed in our environment. Methicillin resistance among Staphylococcus aureus and coagulase-negative staphylococci seems to have stabilized at around 30% and 70%, respectively, however, multiresistance of these species to other antimicrobials, emergence of linezolid resistance, and decreased susceptibility to glycopeptides is a cause of concern. Daptomycin has good antimicrobial activity, although some strains with slightly increased MICs have been detected. Among enterococci, vancomycin resistance is less than 5%, but multiresistance among these microorganisms, emerging linezolid resistance and reports of some isolates with decreased susceptibility to daptomycin are worrying. Adequate use of antimicrobials could help to prevent the increase in resistance and dissemination of these pathogens and will allow their efficacy to be guaranteed in the future.

  15. Thiol-Disulfide Exchange in Gram-Positive Firmicutes.

    PubMed

    Davey, Lauren; Halperin, Scott A; Lee, Song F

    2016-11-01

    Extracytoplasmic thiol-disulfide oxidoreductases (TDORs) catalyze the oxidation, reduction, and isomerization of protein disulfide bonds. Although these processes have been characterized in Gram-negative bacteria, the majority of Gram-positive TDORs have only recently been discovered. Results from recent studies have revealed distinct trends in the types of TDOR used by different groups of Gram-positive bacteria, and in their biological functions. Actinobacteria TDORs can be essential for viability, while Firmicute TDORs influence various physiological processes, including protein stability, oxidative stress resistance, bacteriocin production, and virulence. In this review we discuss the diverse extracytoplasmic TDORs used by Gram-positive bacteria, with a focus on Gram-positive Firmicutes.

  16. Gram-Positive Uropathogens, Polymicrobial Urinary Tract Infection, and the Emerging Microbiota of the Urinary Tract.

    PubMed

    Kline, Kimberly A; Lewis, Amanda L

    2016-04-01

    Gram-positive bacteria are a common cause of urinary-tract infection (UTI), particularly among individuals who are elderly, pregnant, or who have other risk factors for UTI. Here we review the epidemiology, virulence mechanisms, and host response to the most frequently isolated Gram-positive uropathogens: Staphylococcus saprophyticus, Enterococcus faecalis, and Streptococcus agalactiae. We also review several emerging, rare, misclassified, and otherwise underreported Gram-positive pathogens of the urinary tract including Aerococcus, Corynebacterium, Actinobaculum, and Gardnerella. The literature strongly suggests that urologic diseases involving Gram-positive bacteria may be easily overlooked due to limited culture-based assays typically utilized for urine in hospital microbiology laboratories. Some UTIs are polymicrobial in nature, often involving one or more Gram-positive bacteria. We herein review the risk factors and recent evidence for mechanisms of bacterial synergy in experimental models of polymicrobial UTI. Recent experimental data has demonstrated that, despite being cleared quickly from the bladder, some Gram-positive bacteria can impact pathogenic outcomes of co-infecting organisms. When taken together, the available evidence argues that Gram-positive bacteria are important uropathogens in their own right, but that some can be easily overlooked because they are missed by routine diagnostic methods. Finally, a growing body of evidence demonstrates that a surprising variety of fastidious Gram-positive bacteria may either reside in or be regularly exposed to the urinary tract and further suggests that their presence is widespread among women, as well as men. Experimental studies in this area are needed; however, there is a growing appreciation that the composition of bacteria found in the bladder could be a potentially important determinant in urologic disease, including susceptibility to UTI.

  17. Gram-Positive Uropathogens, Polymicrobial Urinary Tract Infection, and the Emerging Microbiota of the Urinary Tract

    PubMed Central

    Kline, Kimberly A.; Lewis, Amanda L.

    2015-01-01

    Gram-positive bacteria are a common cause of urinary tract infection (UTI), particularly among individuals who are elderly, pregnant, or who have other risk factors for UTI. Here we review the epidemiology, virulence mechanisms, and host response to the most frequently isolated Gram-positive uropathogens: Staphylococcus saprophyticus, Enterococcus faecalis, and Streptococcus agalactiae. We also review several emerging, rare, misclassified, and otherwise underreported Gram-positive pathogens of the urinary tract including Aerococcus, Corynebacterium, Actinobaculum, and Gardnerella. The literature strongly suggests that urologic diseases involving Gram-positive bacteria may be easily overlooked due to limited culture-based assays typically utilized for urine in hospital microbiology laboratories. Some UTIs are polymicrobial in nature, often involving one or more Gram-positive bacteria. We herein review the risk factors and recent evidence for mechanisms of bacterial synergy in experimental models of polymicrobial UTI. Recent experimental data has demonstrated that, despite being cleared quickly from the bladder, some Gram-positive bacteria can impact pathogenic outcomes of co-infecting organisms. When taken together, the available evidence argues that Gram-positive bacteria are important uropathogens in their own right, but that some can be easily overlooked because they are missed by routine diagnostic methods. Finally, a growing body of evidence demonstrates that a surprising variety of fastidious Gram-positive bacteria may either reside in or be regularly exposed to the urinary tract and further suggests that their presence is widespread among women, as well as men. Experimental studies in this area are needed; however, there is a growing appreciation that the composition of bacteria found in the bladder could be a potentially important determinant in urologic disease, including susceptibility to UTI. PMID:27227294

  18. In vitro activities of tedizolid compared with other antibiotics against Gram-positive pathogens associated with hospital-acquired pneumonia, skin and soft tissue infection and bloodstream infection collected from 26 hospitals in China.

    PubMed

    Li, Shuguang; Guo, Yu; Zhao, Chunjiang; Chen, Hongbin; Hu, Bijie; Chu, Yunzhuo; Zhang, Zhijie; Hu, Yunjian; Liu, Zhiyong; Du, Yan; Gui, Qiaodi; Ji, Ping; Zeng, Ji; Cao, Bin; Fu, Quan; Zhang, Rong; Wang, Zhongxin; Zhuo, Chao; Feng, Xianju; Jia, Wei; Jin, Yan; Xu, Xuesong; Liao, Kang; Ni, Yuxing; Yu, Yunsong; Xu, Xiuli; Hu, Zhidong; Lei, Jin-E; Yang, Qing; Wang, Hui

    2016-10-01

    To evaluate the in vitro antimicrobial activities of tedizolid, linezolid and other comparators against clinically significant Gram-positive cocci isolates from hospital-acquired pneumonia (HAP), skin and soft tissue infection (SSTI) and bloodstream infection (BSI), 2140 nonduplicate isolates (23.7 % isolated from HAP, 46.8 % from SSTI and 29.5 % from BSI) were consecutively collected in 26 hospitals in 17 cities across China during 2014. These pathogens included 632 methicillin-resistant Staphylococcus aureus, 867 methicillin-sensitive Staphylococcusaureus, 299 coagulase-negative Staphylococcus (CoNS), 104 Enterococcus faecalis, 99 Enterococcusfaecium, 13 Streptococcus pneumoniae, 23 α-haemolytic Streptococcus and 103 β-haemolytic Streptococcus. MICs of routine clinical antibiotics were determined by broth microdilution method according to the Clinical and Laboratory Standards Institute guidelines 2015. Tedizolid, linezolid, vancomycin, daptomycin, teicoplanin and tigecycline showed high in vitro activity against Gram-positive pathogens (≥98.0 % susceptible), and tedizolid exhibited four- to eight fold greater activity than linezolid against the pathogens tested, with MIC90s of methicillin-resistant Staphylococcus aureus, α-haemolytic Streptococcus and β-haemolytic Streptococcus (0.25 vs 2 µg ml-1); methicillin-sensitive Staphylococcu saureus, E. faecalis and E. faecium (0.5 vs 2 µg ml-1); methicillin-resistant CoNS and methicillin-sensitive CoNS (0.25 vs 1 µg ml-1); and Streptococcuspneumoniae (0.125 vs 0.5 µg ml-1). Tedizolid MIC90s associated with different infections did not show significant differences, and the drug exhibited excellent activity against surveyed Gram-positive pathogens associated with HAP, SSTI and BSI, including linezolid-nonsusceptible strains. These data suggest that tedizolid could be an alternative to linezolid for the treatment of infections caused by Gram-positive organisms.

  19. Methods for targetted mutagenesis in gram-positive bacteria

    DOEpatents

    Yang, Yunfeng

    2014-05-27

    The present invention provides a method of targeted mutagenesis in Gram-positive bacteria. In particular, the present invention provides a method that effectively integrates a suicide integrative vector into a target gene in the chromosome of a Gram-positive bacterium, resulting in inactivation of the target gene.

  20. Potential Impact of Rapid Blood Culture Testing for Gram-Positive Bacteremia in Japan with the Verigene Gram-Positive Blood Culture Test

    PubMed Central

    Matsuda, Mari; Iguchi, Shigekazu; Mizutani, Tomonori; Hiramatsu, Keiichi; Tega-Ishii, Michiru; Sansaka, Kaori; Negishi, Kenta; Shimada, Kimie; Umemura, Jun; Notake, Shigeyuki; Yanagisawa, Hideji; Yabusaki, Reiko; Araoka, Hideki; Yoneyama, Akiko

    2017-01-01

    Background. Early detection of Gram-positive bacteremia and timely appropriate antimicrobial therapy are required for decreasing patient mortality. The purpose of our study was to evaluate the performance of the Verigene Gram-positive blood culture assay (BC-GP) in two special healthcare settings and determine the potential impact of rapid blood culture testing for Gram-positive bacteremia within the Japanese healthcare delivery system. Furthermore, the study included simulated blood cultures, which included a library of well-characterized methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) isolates reflecting different geographical regions in Japan. Methods. A total 347 BC-GP assays were performed on clinical and simulated blood cultures. BC-GP results were compared to results obtained by reference methods for genus/species identification and detection of resistance genes using molecular and MALDI-TOF MS methodologies. Results. For identification and detection of resistance genes at two clinical sites and simulated blood cultures, overall concordance of BC-GP with reference methods was 327/347 (94%). The time for identification and antimicrobial resistance detection by BC-GP was significantly shorter compared to routine testing especially at the cardiology hospital, which does not offer clinical microbiology services on weekends and holidays. Conclusion. BC-GP generated accurate identification and detection of resistance markers compared with routine laboratory methods for Gram-positive organisms in specialized clinical settings providing more rapid results than current routine testing. PMID:28316631

  1. Invasive gram-positive bacterial infection in cancer patients.

    PubMed

    Holland, Thomas; Fowler, Vance G; Shelburne, Samuel A

    2014-11-15

    Systematic studies have shown that gram-positive organisms are the leading cause of invasive bacterial disease in patients with cancer. A broad range of gram-positive bacteria cause serious infections in the cancer patient with the greatest burden of disease being due to staphylococci, streptococci, and enterococci. The evolution of cancer therapy and the changing epidemiology of major gram-positive pathogens mean that ongoing efforts are needed to understand and mitigate the impact of these bacteria in patients with malignancy. The development of novel antibacterials, optimization of treatment approaches, implementation of improved vaccines, and manipulation of the microbiome are all active areas of investigation in the goal of improving the survival of the cancer patient through amelioration of the disease burden of gram-positive bacteria.

  2. Biogenesis of the Gram-positive bacterial cell envelope.

    PubMed

    Siegel, Sara D; Liu, Jun; Ton-That, Hung

    2016-12-01

    The Gram-positive cell envelope serves as a molecular platform for surface display of capsular polysaccharides, wall teichoic acids (WTAs), lipoteichoic acids (LTAs), lipoproteins, surface proteins and pili. WTAs, LTAs, and sortase-assembled pili are a few features that make the Gram-positive cell envelope distinct from the Gram-negative counterpart. Interestingly, a set of LytR-CpsA-Psr family proteins, found in all Gram-positives but limited to a minority of Gram-negative organisms, plays divergent functions, while decorating the cell envelope with glycans. Furthermore, a phylum of Gram-positive bacteria, the actinobacteria, appear to employ oxidative protein folding as the major folding mechanism, typically occurring in an oxidizing environment of the Gram-negative periplasm. These distinctive features will be highlighted, along with recent findings in the cell envelope biogenesis.

  3. The thuggacins, novel antibacterial macrolides from Sorangium cellulosum acting against selected Gram-positive bacteria.

    PubMed

    Irschik, Herbert; Reichenbach, Hans; Höfle, Gerhard; Jansen, Rolf

    2007-12-01

    In our screening program we found an activity against some Gram-positive bacteria, including mycobacteria in the culture supernatant of Sorangium cellulosum strain So ce895. The antibiotic responsible for this activity was isolated and named thuggacin. Initial studies towards the mechanism of action showed that thuggacin A inhibits a late step of the respiratory chain of some bacteria.

  4. First Report of Human Infection by Agromyces mediolanus, a Gram-Positive Organism Found in Soil

    PubMed Central

    Sridhar, Siddharth; Wang, Angela Y. M.; Chan, Jasper F. W.; Yip, Cyril C. Y.; Woo, Patrick C. Y.; Yuen, Kwok-Yung

    2015-01-01

    We report the first human infection by a member of the Agromyces genus, a group of Gram-positive bacteria found in soil. A patient with a long-term venous catheter developed bacteremia due to a non-vancomycin-susceptible isolate of Agromyces mediolanus. Rapid identification was possible by matrix-assisted laser desorption ionization–time of flight mass spectrometry. PMID:26202108

  5. Case-Control Study of Telavancin as an Alternative Treatment for Gram-Positive Bloodstream Infections in Patients with Cancer.

    PubMed

    Chaftari, Anne-Marie; Hachem, Ray; Jordan, Mary; Garoge, Kumait; Al Hamal, Zainab; El Zakhem, Aline; Viola, George M; Granwehr, Bruno; Mulanovich, Victor; Gagel, Andrew; Reitzel, Ruth; Yousif, Ammar; Jiang, Ying; Raad, Issam

    2015-10-19

    Gram-positive bacterial infections are an important cause of morbidity and death among cancer patients, despite current therapy. In this case-control study, we evaluated the clinical outcomes and safety of telavancin in cancer patients with uncomplicated Gram-positive bloodstream infections (BSIs). Between March 2011 and May 2013, we enrolled cancer patients with uncomplicated Gram-positive BSIs to receive intravenous telavancin therapy for at least 14 days for Staphylococcus aureus and 7 days for other Gram-positive cocci. Patients with baseline creatinine clearance (CLCR) values of >50 ml/min received 10 mg/kg/day of telavancin, and those with CLCR values between 30 and 49 ml/min received 7.5 mg/kg/day. Patients were compared with a retrospective cohort of 39 historical patients with Gram-positive BSIs, matched for underlying malignancy, infecting organism, and neutropenia status, who had been treated with vancomycin. A total of 78 patients were analyzed, with 39 in each group. The most common pathogen causing BSIs was S. aureus (51%), followed by alpha-hemolytic streptococci (23%), Enterococcus spp. (15%), coagulase-negative staphylococci (8%), and beta-hemolytic streptococci (3%). Sixty-two percent of patients had hematological malignancies, and 38% had solid tumors; 51% of the patients were neutropenic. The overall response rate determined by clinical outcome and microbiological eradication at 72 h following the initiation of therapy, in the absence of relapse, deep-seated infections, and/or infection-related death, was better with telavancin than with vancomycin (86% versus 61%; P = 0.013). Rates of drug-related adverse events were similar in the two groups (telavancin, 31%; vancomycin, 23%; P = 0.79), with similar rates of renal adverse events. Telavancin may provide a useful alternative to standard vancomycin therapy for Gram-positive BSIs in cancer patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT01321879.).

  6. Case-Control Study of Telavancin as an Alternative Treatment for Gram-Positive Bloodstream Infections in Patients with Cancer

    PubMed Central

    Hachem, Ray; Jordan, Mary; Garoge, Kumait; Al Hamal, Zainab; El Zakhem, Aline; Viola, George M.; Granwehr, Bruno; Mulanovich, Victor; Gagel, Andrew; Reitzel, Ruth; Yousif, Ammar; Jiang, Ying; Raad, Issam

    2015-01-01

    Gram-positive bacterial infections are an important cause of morbidity and death among cancer patients, despite current therapy. In this case-control study, we evaluated the clinical outcomes and safety of telavancin in cancer patients with uncomplicated Gram-positive bloodstream infections (BSIs). Between March 2011 and May 2013, we enrolled cancer patients with uncomplicated Gram-positive BSIs to receive intravenous telavancin therapy for at least 14 days for Staphylococcus aureus and 7 days for other Gram-positive cocci. Patients with baseline creatinine clearance (CLCR) values of >50 ml/min received 10 mg/kg/day of telavancin, and those with CLCR values between 30 and 49 ml/min received 7.5 mg/kg/day. Patients were compared with a retrospective cohort of 39 historical patients with Gram-positive BSIs, matched for underlying malignancy, infecting organism, and neutropenia status, who had been treated with vancomycin. A total of 78 patients were analyzed, with 39 in each group. The most common pathogen causing BSIs was S. aureus (51%), followed by alpha-hemolytic streptococci (23%), Enterococcus spp. (15%), coagulase-negative staphylococci (8%), and beta-hemolytic streptococci (3%). Sixty-two percent of patients had hematological malignancies, and 38% had solid tumors; 51% of the patients were neutropenic. The overall response rate determined by clinical outcome and microbiological eradication at 72 h following the initiation of therapy, in the absence of relapse, deep-seated infections, and/or infection-related death, was better with telavancin than with vancomycin (86% versus 61%; P = 0.013). Rates of drug-related adverse events were similar in the two groups (telavancin, 31%; vancomycin, 23%; P = 0.79), with similar rates of renal adverse events. Telavancin may provide a useful alternative to standard vancomycin therapy for Gram-positive BSIs in cancer patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT01321879.) PMID

  7. Diversity of pigmented Gram-positive bacteria associated with marine macroalgae from Antarctica.

    PubMed

    Leiva, Sergio; Alvarado, Pamela; Huang, Ying; Wang, Jian; Garrido, Ignacio

    2015-12-01

    Little is known about the diversity and roles of Gram-positive and pigmented bacteria in Antarctic environments, especially those associated with marine macroorganisms. This work is the first study about the diversity and antimicrobial activity of culturable pigmented Gram-positive bacteria associated with marine Antarctic macroalgae. A total of 31 pigmented Gram-positive strains were isolated from the surface of six species of macroalgae collected in the King George Island, South Shetland Islands. On the basis of 16S rRNA gene sequence similarities ≥99%, 18 phylotypes were defined, which were clustered into 11 genera of Actinobacteria (Agrococcus, Arthrobacter, Brachybacterium, Citricoccus, Kocuria, Labedella, Microbacterium, Micrococcus, Rhodococcus, Salinibacterium and Sanguibacter) and one genus of the Firmicutes (Staphylococcus). It was found that five isolates displayed antimicrobial activity against a set of macroalgae-associated bacteria. The active isolates were phylogenetically related to Agrococcus baldri, Brachybacterium rhamnosum, Citricoccus zhacaiensis and Kocuria palustris. The results indicate that a diverse community of pigmented Gram-positive bacteria is associated with Antartic macroalgae and suggest its potential as a promising source of antimicrobial and pigmented natural compounds. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  8. Phylogenetic Diversity of Gram-Positive Bacteria Cultured from Marine Sediments▿ †

    PubMed Central

    Gontang, Erin A.; Fenical, William; Jensen, Paul R.

    2007-01-01

    Major advances in our understanding of marine bacterial diversity have been gained through studies of bacterioplankton, the vast majority of which appear to be gram negative. Less effort has been devoted to studies of bacteria inhabiting marine sediments, yet there is evidence to suggest that gram-positive bacteria comprise a relatively large proportion of these communities. To further expand our understanding of the aerobic gram-positive bacteria present in tropical marine sediments, a culture-dependent approach was applied to sediments collected in the Republic of Palau from the intertidal zone to depths of 500 m. This investigation resulted in the isolation of 1,624 diverse gram-positive bacteria spanning 22 families, including many that appear to represent new taxa. Phylogenetic analysis of 189 representative isolates, based on 16S rRNA gene sequence data, indicated that 124 (65.6%) belonged to the class Actinobacteria while the remaining 65 (34.4%) were members of the class Bacilli. Using a sequence identity value of ≥98%, the 189 isolates grouped into 78 operational taxonomic units, of which 29 (37.2%) are likely to represent new taxa. The high degree of phylogenetic novelty observed during this study highlights the fact that a great deal remains to be learned about the diversity of gram-positive bacteria in marine sediments. PMID:17400789

  9. Isolation, cultivation and genomic analysis of magnetosome biomineralization genes of a new genus of South-seeking magnetotactic cocci within the Alphaproteobacteria

    SciTech Connect

    Morillo, Viviana; Abreu, Fernanda; Araujo, Ana C; de Almeida, Luiz G; Enrich-Prast, Alex; Farina, Marcos; de Vasconcelos, Ana T; Bazylinski, Dennis A; Lins, Ulysses

    2014-01-01

    Although magnetotactic bacteria (MTB) are ubiquitous in aquatic habitats, they are still considered fastidious microorganisms with regard to growth and cultivation with only a relatively low number of axenic cultures available to date. Here, we report the first axenic culture of an MTB isolated in the Southern Hemisphere (Itaipu Lagoon in Rio de Janeiro, Brazil). Cells of this new isolate are coccoid to ovoid in morphology and grow microaerophilically in semi-solid medium containing an oxygen concentration ([O2]) gradient either under chemoorganoheterotrophic or chemolithoautotrophic conditions. Each cell contains a single chain of approximately 10 elongated cuboctahedral magnetite (Fe3O4) magnetosomes. Phylogenetic analysis based on the 16S rRNA gene sequence shows that the coccoid MTB isolated in this study represents a new genus in the Alphaproteobacteria; the name Magnetofaba australis strain IT-1 is proposed. Preliminary genomic data obtained by pyrosequencing shows that M. australis strain IT-1 contains a genomic region with genes involved in biomineralization similar to those found in the most closely related magnetotactic cocci Magnetococcus marinus strain MC-1. However, organization of the magnetosome genes differs from M. marinus.

  10. Isolation, cultivation and genomic analysis of magnetosome biomineralization genes of a new genus of South-seeking magnetotactic cocci within the Alphaproteobacteria

    PubMed Central

    Morillo, Viviana; Abreu, Fernanda; Araujo, Ana C.; de Almeida, Luiz G. P.; Enrich-Prast, Alex; Farina, Marcos; de Vasconcelos, Ana T. R.; Bazylinski, Dennis A.; Lins, Ulysses

    2014-01-01

    Although magnetotactic bacteria (MTB) are ubiquitous in aquatic habitats, they are still considered fastidious microorganisms with regard to growth and cultivation with only a relatively low number of axenic cultures available to date. Here, we report the first axenic culture of an MTB isolated in the Southern Hemisphere (Itaipu Lagoon in Rio de Janeiro, Brazil). Cells of this new isolate are coccoid to ovoid in morphology and grow microaerophilically in semi-solid medium containing an oxygen concentration ([O2]) gradient either under chemoorganoheterotrophic or chemolithoautotrophic conditions. Each cell contains a single chain of approximately 10 elongated cuboctahedral magnetite (Fe3O4) magnetosomes. Phylogenetic analysis based on the 16S rRNA gene sequence shows that the coccoid MTB isolated in this study represents a new genus in the Alphaproteobacteria; the name Magnetofaba australis strain IT-1 is proposed. Preliminary genomic data obtained by pyrosequencing shows that M. australis strain IT-1 contains a genomic region with genes involved in biomineralization similar to those found in the most closely related magnetotactic cocci Magnetococcus marinus strain MC-1. However, organization of the magnetosome genes differs from M. marinus. PMID:24616719

  11. In vitro activity of ceftaroline-avibactam against gram-negative and gram-positive pathogens isolated from patients in Canadian hospitals from 2010 to 2012: results from the CANWARD surveillance study.

    PubMed

    Karlowsky, James A; Adam, Heather J; Baxter, Melanie R; Lagacé-Wiens, Philippe R S; Walkty, Andrew J; Hoban, Daryl J; Zhanel, George G

    2013-11-01

    The in vitro activities of ceftaroline-avibactam, ceftaroline, and comparative agents were determined for a collection of bacterial pathogens frequently isolated from patients seeking care at 15 Canadian hospitals from January 2010 to December 2012. In total, 9,758 isolates were tested by using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method (document M07-A9, 2012), with MICs interpreted by using CLSI breakpoints (document M100-S23, 2013). Ceftaroline-avibactam demonstrated potent activity (MIC90, ≤ 0.5 μg/ml) against Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, Morganella morganii, Citrobacter freundii, and Haemophilus influenzae; >99% of isolates of E. coli, K. pneumoniae, K. oxytoca, P. mirabilis, M. morganii, C. freundii, and H. influenzae were susceptible to ceftaroline-avibactam according to CLSI MIC interpretative criteria for ceftaroline. Ceftaroline was less active than ceftaroline-avibactam against all species of Enterobacteriaceae tested, with rates of susceptibility ranging from 93.9% (P. mirabilis) to 54.0% (S. marcescens). All isolates of methicillin-susceptible Staphylococcus aureus (MIC90, 0.25 μg/ml) and 99.6% of methicillin-resistant S. aureus isolates (MIC90, 1 μg/ml) were susceptible to ceftaroline; the addition of avibactam to ceftaroline did not alter its activity against staphylococci or streptococci. All isolates of Streptococcus pneumoniae (MIC90, 0.03 μg/ml), Streptococcus pyogenes (MIC90, ≤ 0.03 μg/ml), and Streptococcus agalactiae (MIC90, 0.015 μg/ml) tested were susceptible to ceftaroline. We conclude that combining avibactam with ceftaroline expanded its spectrum of activity to include most isolates of Enterobacteriaceae resistant to third-generation cephalosporins, including extended-spectrum β-lactamase (ESBL)- and AmpC-producing E. coli and ESBL-producing K. pneumoniae, while maintaining

  12. In Vitro Activity of Ceftaroline-Avibactam against Gram-Negative and Gram-Positive Pathogens Isolated from Patients in Canadian Hospitals from 2010 to 2012: Results from the CANWARD Surveillance Study

    PubMed Central

    Adam, Heather J.; Baxter, Melanie R.; Lagacé-Wiens, Philippe R. S.; Walkty, Andrew J.; Hoban, Daryl J.; Zhanel, George G.

    2013-01-01

    The in vitro activities of ceftaroline-avibactam, ceftaroline, and comparative agents were determined for a collection of bacterial pathogens frequently isolated from patients seeking care at 15 Canadian hospitals from January 2010 to December 2012. In total, 9,758 isolates were tested by using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method (document M07-A9, 2012), with MICs interpreted by using CLSI breakpoints (document M100-S23, 2013). Ceftaroline-avibactam demonstrated potent activity (MIC90, ≤0.5 μg/ml) against Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Proteus mirabilis, Enterobacter cloacae, Enterobacter aerogenes, Serratia marcescens, Morganella morganii, Citrobacter freundii, and Haemophilus influenzae; >99% of isolates of E. coli, K. pneumoniae, K. oxytoca, P. mirabilis, M. morganii, C. freundii, and H. influenzae were susceptible to ceftaroline-avibactam according to CLSI MIC interpretative criteria for ceftaroline. Ceftaroline was less active than ceftaroline-avibactam against all species of Enterobacteriaceae tested, with rates of susceptibility ranging from 93.9% (P. mirabilis) to 54.0% (S. marcescens). All isolates of methicillin-susceptible Staphylococcus aureus (MIC90, 0.25 μg/ml) and 99.6% of methicillin-resistant S. aureus isolates (MIC90, 1 μg/ml) were susceptible to ceftaroline; the addition of avibactam to ceftaroline did not alter its activity against staphylococci or streptococci. All isolates of Streptococcus pneumoniae (MIC90, 0.03 μg/ml), Streptococcus pyogenes (MIC90, ≤0.03 μg/ml), and Streptococcus agalactiae (MIC90, 0.015 μg/ml) tested were susceptible to ceftaroline. We conclude that combining avibactam with ceftaroline expanded its spectrum of activity to include most isolates of Enterobacteriaceae resistant to third-generation cephalosporins, including extended-spectrum β-lactamase (ESBL)- and AmpC-producing E. coli and ESBL-producing K. pneumoniae, while maintaining

  13. Evaluation of the Bruker MALDI Biotyper for Identification of Gram-Positive Rods: Development of a Diagnostic Algorithm for the Clinical Laboratory

    PubMed Central

    Bloemberg, Guido V.; Zbinden, Reinhard; Böttger, Erik C.; Hombach, Michael

    2014-01-01

    Reported matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) identification rates of Gram-positive rods (GPR) are low compared to identification rates of Gram-positive cocci. In this study, three sample preparation methods were compared for MALDI-TOF MS identification of 190 well-characterized GPR strains: direct transfer, direct transfer-formic acid preparation, and ethanol-formic acid extraction. Using the interpretation criteria recommended by the manufacturer, identification rates were significantly higher for direct transfer-formic acid preparation and ethanol-formic acid extraction than for direct transfer. Reducing the species cutoff from 2.0 to 1.7 significantly increased species identification rates. In a subsequent prospective study, 215 clinical GPR isolates were analyzed by MALDI-TOF MS, and the results were compared to those for identification using conventional methods, with discrepancies being resolved by 16S rRNA and rpoB gene analysis. Using the direct transfer-formic acid preparation and a species cutoff of 1.7, congruencies on the genus and species levels of 87.4% and 79.1%, respectively, were achieved. In addition, the rate of nonidentified isolates dropped from 12.1% to 5.6% when using an extended database, i.e., the Bruker database amended by reference spectra of the 190 GPR of the retrospective study. Our data demonstrate three ways to improve GPR identification by the Bruker MALDI Biotyper, (i) optimize sample preparation using formic acid, (ii) reduce cutoff scores for species identification, and (iii) expand the database. Based on our results, we suggest an identification algorithm for the clinical laboratory combining MALDI-TOF MS with nucleic acid sequencing. PMID:24452159

  14. Multidrug resistance in hydrocarbon-tolerant Gram-positive and Gram-negative bacteria.

    PubMed

    Stancu, Mihaela Marilena; Grifoll, Magdalena

    2011-01-01

    New Gram-positive and Gram-negative bacteria were isolated from Poeni oily sludge, using enrichment procedures. The six Gram-positive strains belong to Bacillus, Lysinibacillus and Rhodococcus genera. The eight Gram-negative strains belong to Shewanella, Aeromonas, Pseudomonas and Klebsiella genera. Isolated bacterial strains were tolerant to saturated (i.e., n-hexane, n-heptane, n-decane, n-pentadecane, n-hexadecane, cyclohexane), monoaromatic (i.e., benzene, toluene, styrene, xylene isomers, ethylbenzene, propylbenzene) and polyaromatic (i.e., naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons, and also resistant to different antimicrobial agents (i.e., ampicillin, kanamycin, rhodamine 6G, crystal violet, malachite green, sodium dodecyl sulfate). The presence of hydrophilic antibiotics like ampicillin or kanamycin in liquid LB-Mg medium has no effects on Gram-positive and Gram-negative bacteria resistance to toxic compounds. The results indicated that Gram-negative bacteria are less sensitive to toxic compounds than Gram-positive bacteria, except one bacteria belonging to Lysinibacillus genus. There were observed cellular and molecular modifications induced by ampicillin or kanamycin to isolated bacterial strains. Gram-negative bacteria possessed between two and four catabolic genes (alkB, alkM, alkB/alkB1, todC1, xylM, PAH dioxygenase, catechol 2,3-dioxygenase), compared with Gram-positive bacteria (except one bacteria belonging to Bacillus genus) which possessed one catabolic gene (alkB/alkB1). Transporter genes (HAE1, acrAB) were detected only in Gram-negative bacteria.

  15. Gram-negative and Gram-positive bacterial extracellular vesicles.

    PubMed

    Kim, Ji Hyun; Lee, Jaewook; Park, Jaesung; Gho, Yong Song

    2015-04-01

    Like mammalian cells, Gram-negative and Gram-positive bacteria release nano-sized membrane vesicles into the extracellular environment either in a constitutive manner or in a regulated manner. These bacterial extracellular vesicles are spherical bilayered proteolipids enriched with bioactive proteins, lipids, nucleic acids, and virulence factors. Recent progress in this field supports the critical pathophysiological functions of these vesicles in both bacteria-bacteria and bacteria-host interactions. This review provides an overview of the current understanding on Gram-negative and Gram-positive bacterial extracellular vesicles, especially regarding the biogenesis, components, and functions in poly-species communities. We hope that this review will stimulate additional research in this emerging field of bacterial extracellular vesicles and contribute to the development of extracellular vesicle-based diagnostic tools and effective vaccines against pathogenic Gram-negative and Gram-positive bacteria.

  16. Multiplex identification of drug-resistant Gram-positive pathogens using stuffer-free MLPA system.

    PubMed

    Chung, Boram; Park, Chulmin; Cho, Sung-Yeon; Shin, Sun; Yim, Seon-Hee; Jung, Gyoo Yeol; Lee, Dong-Gun; Chung, Yeun-Jun

    2016-12-01

    Early detection of pathogens from blood and identification of their drug resistance are essential for sepsis management. However, conventional culture-based methods require relatively longer time to identify drug-resistant pathogens, which delays therapeutic decisions. For precise multiplex detection of drug-resistant Gram-positive pathogens, we developed a method by using stuffer-free multiplex ligation-dependent probe amplification (MLPA) coupled with high-resolution CE single-strand conformation polymorphisms (CE-SSCP) system. We designed three probe sets for genes specific to Gram-positive species (Staphylococcus aureus: nuc, Enterococcus faecium: sodA, and Streptococcus pneumoniae: lytA) and two sets for genes associated with drug resistance (mecA and vanA) to discriminate major Gram-positive pathogens with the resistance. A total of 94 different strains (34 reference strains and 60 clinical isolates) were used to validate this method and strain-specific peaks were successfully observed for all the strains. To improve sensitivity of the method, a target-specific preamplification step was introduced and, consequently, the sensitivity increased from 10 pg to 100 fg. We also reduced a total assay time to 8 h by optimizing hybridization time without compromising test sensitivity. Taken together, our multiplex detection system can improve detection of drug-resistant Gram-positive pathogens from sepsis patients' blood.

  17. Protein Secretion in Gram-Positive Bacteria: From Multiple Pathways to Biotechnology.

    PubMed

    Anné, Jozef; Economou, Anastassios; Bernaerts, Kristel

    2016-11-25

    A number of Gram-positive bacteria are important players in industry as producers of a diverse array of economically interesting metabolites and proteins. As discussed in this overview, several Gram-positive bacteria are valuable hosts for the production of heterologous proteins. In contrast to Gram-negative bacteria, proteins secreted by Gram-positive bacteria are released into the culture medium where conditions for correct folding are more appropriate, thus facilitating the isolation and purification of active proteins. Although seven different protein secretion pathways have been identified in Gram-positive bacteria, the majority of heterologous proteins are produced via the general secretion or Sec pathway. Not all proteins are equally well secreted, because heterologous protein production often faces bottlenecks including hampered secretion, susceptibility to proteases, secretion stress, and metabolic burden. These bottlenecks are associated with reduced yields leading to non-marketable products. In this chapter, besides a general overview of the different protein secretion pathways, possible hurdles that may hinder efficient protein secretion are described and attempts to improve yield are discussed including modification of components of the Sec pathway. Attention is also paid to omics-based approaches that may offer a more rational approach to optimize production of heterologous proteins.

  18. Clinical impact of antibiotic-resistant Gram-positive pathogens.

    PubMed

    Lode, H M

    2009-03-01

    The European Union's attention to the problem of antibacterial resistance will soon reach a 10-year mark, but the rates of resistance in Gram-positive and Gram-negative bacteria are still increasing. This review focuses on the clinical impact of resistant Gram-positive bacteria on patients. Multiple drug resistance in pneumococcal infections will lead to more treatment failures and higher mortality, which so far have been seen with penicillins and pathogens with high-level resistance. Several studies have demonstrated higher mortality, prolonged length of hospital stay and higher costs associated with methicillin-resistant Staphylococcus aureus infections, in comparison with methicillin-susceptible Staphylococcus aureus infections. Similarly, vancomycin-resistant enterococci bloodstream infections have a negative impact with respect to mortality, length of hospital stay and costs, in comparison with infections due to vancomycin-susceptible enterococci. Several distinctive prophylactic and therapeutic approaches have to be undertaken to successfully prevent the clinical consequences of antibiotic resistance in Gram-positive bacteria. This review addresses the impact of antibiotic-resistant Gram-positive pathogens on clinical outcomes.

  19. Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria.

    PubMed

    Nawrocki, Kathryn L; Crispell, Emily K; McBride, Shonna M

    2014-10-13

    Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis.

  20. Protein secretion and surface display in Gram-positive bacteria

    PubMed Central

    Schneewind, Olaf; Missiakas, Dominique M.

    2012-01-01

    The cell wall peptidoglycan of Gram-positive bacteria functions as a surface organelle for the transport and assembly of proteins that interact with the environment, in particular, the tissues of an infected host. Signal peptide-bearing precursor proteins are secreted across the plasma membrane of Gram-positive bacteria. Some precursors carry C-terminal sorting signals with unique sequence motifs that are cleaved by sortase enzymes and linked to the cell wall peptidoglycan of vegetative forms or spores. The sorting signals of pilin precursors are cleaved by pilus-specific sortases, which generate covalent bonds between proteins leading to the assembly of fimbrial structures. Other precursors harbour surface (S)-layer homology domains (SLH), which fold into a three-pronged spindle structure and bind secondary cell wall polysaccharides, thereby associating with the surface of specific Gram-positive microbes. Type VII secretion is a non-canonical secretion pathway for WXG100 family proteins in mycobacteria. Gram-positive bacteria also secrete WXG100 proteins and carry unique genes that either contribute to discrete steps in secretion or represent distinctive substrates for protein transport reactions. PMID:22411983

  1. Presence of squalene in gram-positive bacteria.

    PubMed Central

    Amdur, B H; Szabo, E I; Socransky, S S

    1978-01-01

    The presence of the isoprenoid squalene, synthesized de novo, was demonstrated in 64 out of 73 strains of gram-positive bacteria by thin-layer chromatography. This observation was confirmed by gas-liquid chromatography, chemical reactivity, incorporation of radiolabeled precursor, and by gas chromatography mass spectroscopy of thin-layer chromatography-recovered material. PMID:670148

  2. Antimicrobial Peptide Resistance Mechanisms of Gram-Positive Bacteria

    PubMed Central

    Nawrocki, Kathryn L.; Crispell, Emily K.; McBride, Shonna M.

    2014-01-01

    Antimicrobial peptides, or AMPs, play a significant role in many environments as a tool to remove competing organisms. In response, many bacteria have evolved mechanisms to resist these peptides and prevent AMP-mediated killing. The development of AMP resistance mechanisms is driven by direct competition between bacterial species, as well as host and pathogen interactions. Akin to the number of different AMPs found in nature, resistance mechanisms that have evolved are just as varied and may confer broad-range resistance or specific resistance to AMPs. Specific mechanisms of AMP resistance prevent AMP-mediated killing against a single type of AMP, while broad resistance mechanisms often lead to a global change in the bacterial cell surface and protect the bacterium from a large group of AMPs that have similar characteristics. AMP resistance mechanisms can be found in many species of bacteria and can provide a competitive edge against other bacterial species or a host immune response. Gram-positive bacteria are one of the largest AMP producing groups, but characterization of Gram-positive AMP resistance mechanisms lags behind that of Gram-negative species. In this review we present a summary of the AMP resistance mechanisms that have been identified and characterized in Gram-positive bacteria. Understanding the mechanisms of AMP resistance in Gram-positive species can provide guidelines in developing and applying AMPs as therapeutics, and offer insight into the role of resistance in bacterial pathogenesis. PMID:25419466

  3. Contemporary tetracycline susceptibility testing: doxycycline MIC methods and interpretive criteria (CLSI and EUCAST) performance when testing Gram-positive pathogens.

    PubMed

    Jones, Ronald N; Stilwell, Matthew G; Wilson, Michael L; Mendes, Rodrigo E

    2013-05-01

    International susceptibility testing breakpoint organizations and regulatory agencies have markedly differing interpretive criteria for the tetracycline class. Here we examined the magnitude of these differences for doxycycline and tetracycline hydrochloride (HCL) when tested against a collection of 13,176 Gram-positive cocci from a worldwide surveillance network (SENTRY Antimicrobial Surveillance Program, 2010). Clinical and Laboratory Standards Institute (CLSI) breakpoints are routinely higher, usually 4-fold, compared to those of the European Committee on Antimicrobial Susceptibility Testing (EUCAST); however, CLSI recently (2013) modified Streptococcus pneumoniae breakpoints (≤ 2 μg/mL in 2012) to ≤ 0.25 and ≤ 1 μg/mL for doxycycline and tetracycline HCL, respectively. We report that these changes are a promising step toward international breakpoint harmonization, but lack a comprehensive approach needed for testing tetracyclines against all Gram-positive cocci. Generally, EUCAST breakpoint criteria showed i) lower spectrums (reduced susceptibility rates) for the tetracyclines, but highest for doxycycline versus all species examined; ii) greater test accuracy (lower predictive categorical errors), especially for tetracycline to predict doxycycline susceptibility (99.91%); and iii) zone diameter correlate breakpoints which are generally available online. Molecular tests for tet resistance genes demonstrate that tet (K) and tet (M) containing strains can occur in the susceptible population of MIC results by both CLSI and EUCAST breakpoint criteria. In summary, doxycycline continues to show greater comparative potency versus tetracycline HCL against all monitored Gram-positive species and the international harmonization of tetracycline breakpoints should be a priority, as the most recent CLSI update only addressed 1 streptococcal species and 2 tetracycline agents.

  4. Multiple Responses of Gram-Positive and Gram-Negative Bacteria to Mixture of Hydrocarbons

    PubMed Central

    Marilena Lăzăroaie, Mihaela

    2010-01-01

    Most of our knowledge about pollutants and the way they are biodegraded in the environment has previously been shaped by laboratory studies using hydrocarbon-degrading bacterial strains isolated from polluted sites. In present study Gram-positive (Mycobacterium sp. IBBPo1, Oerskovia sp. IBBPo2, Corynebacterium sp. IBBPo3) and Gram-negative (Chryseomonas sp. IBBPo7, Pseudomonas sp. IBBPo10, Burkholderia sp. IBBPo12) bacteria, isolated from oily sludge, were found to be able to tolerate pure and mixture of saturated hydrocarbons, as well as pure and mixture of monoaromatic and polyaromatic hydrocarbons. Isolated Gram-negative bacteria were more tolerant to mixture of saturated (n-hexane, n-hexadecane, cyclohexane), monoaromatic (benzene, toluene, ethylbenzene) and polyaromatic (naphthalene, 2-methylnaphthalene, fluorene) hydrocarbons than Gram-positive bacteria. There were observed cellular and molecular modifications induced by mixture of saturated, monoaromatic and polyaromatic hydrocarbons to Gram-positive and Gram-negative bacteria. These modifications differ from one strain to another and even for the same bacterial strain, according to the nature of hydrophobic substrate. PMID:24031541

  5. Diversity and abundance of Gram positive bacteria in a tidal flat ecosystem.

    PubMed

    Stevens, Heike; Brinkhoff, Thorsten; Rink, Beate; Vollmers, John; Simon, Meinhard

    2007-07-01

    Gram positive bacteria recently have been identified as important components of freshwater ecosystems and are also present in marine environments. However, their quantitative significance and possible role in the latter systems is still little studied, in particular in coastal regions. Therefore, we investigated the abundance and composition of Gram positive bacteria in the Wadden Sea, a tidal flat ecosystem in the German Bight of the North Sea. Applying fluorescence in situ hybridization we found that Actinobacteria constitute 4-7% of total bacteria in the Wadden Sea and slightly higher proportions in a freshwater drainage channel connected to the sea by a sluice. The application of denaturing gradient gel electrophoresis of 16S rRNA gene fragments after amplification by an Actinobacteria-specific primer set and subsequent sequencing showed that the composition of the actinobacterial community in the Wadden Sea was distinctly different from that in the freshwater system. A bacterial clone library of 111 clones yielded eight Gram positive phylotypes which are related closely to other marine phylotypes including the Marine Actinobacteria Clade but also to freshwater phylotypes. We applied dilution cultures, enriched with various biopolymers, Marine Broth and Fucus vesiculosus extracts, for isolating bacteria from the bulk water, suspended aggregates, the oxic surface and oxic/anoxic transition zone of the sediment. Fifty-three isolates affiliated to seven families of the order Actinomycetales and nine isolates to the family Bacillaceae. The salinity range (1-45 per thousand NaCl) and growth optimum of 14 strains from various families showed that all except one strain exhibited a rather broad range of sustained growth from 1 per thousand to >or= 20 per thousand NaCl and several strains exhibited an optimum of > 10 per thousand NaCl. The results indicate that the Gram positive bacterial community in the Wadden Sea is surprisingly diverse and consists mainly of

  6. Quorum Quenching Strategy Targeting Gram-Positive Pathogenic Bacteria.

    PubMed

    Singh, Ravindra Pal; Desouky, Said E; Nakayama, Jiro

    2016-01-01

    Quorum sensing (QS) is a cell density-dependent regulatory system that orchestrates the group behavior of unicellular organisms by synchronizing the expression of certain gene(s) within the clonal community of same species. Bacterial pathogens often employ QS system to establish efficiently an infection. A large part of low GC Gram-positive bacteria belonging to phylum Firmicutes use thiolactone/lactone peptides as communication signals so-called autoinducing peptides (AIPs) to coordinate QS circuit. In particular, QS of staphylococci, enterococci, and clostridia have been intensively studied in terms of alternative target of anti-pathogenic chemotherapy independent of bactericidal antibiotics. Thus far, a number of quorum quenching (QQ) agents that targeting the QS circuit of these Gram-positive pathogens have been developed by random screening of natural compounds or rationale design of AIP antagonists. This review summarizes those QQ agents and previews their potential as post-antibiotic drugs.

  7. Which antibiotic for resistant Gram-positives, and why?

    PubMed

    Bradley, John S

    2014-01-01

    Increasing resistance in Gram-positive pathogens, particularly Staphylococcus aureus, and enterococcus, has become a major clinical problem, particularly in the hospital environment, causing significant morbidity and mortality in both healthy hosts and in those with underlying comorbidities. Increased resistance drives the use of empiric therapy with less well-studied and potentially more toxic agents. Resistance mechanisms for currently recommended agents are discussed, with options for therapy of resistant pathogens. For any new agent used, resistance is likely to develop, which underscores the concept that both antibiotics and antimicrobial resistance are ancient, and only by prudent use of antimicrobial agents and effective infection control measures when resistance arises, will effective agents be available to treat Gram-positive pathogens in the future.

  8. Cyclic diguanylate signaling in Gram-positive bacteria.

    PubMed

    Purcell, Erin B; Tamayo, Rita

    2016-09-01

    The nucleotide second messenger 3'-5' cyclic diguanylate monophosphate (c-di-GMP) is a central regulator of the transition between motile and non-motile lifestyles in bacteria, favoring sessility. Most research investigating the functions of c-di-GMP has focused on Gram-negative species, especially pathogens. Recent work in Gram-positive species has revealed that c-di-GMP plays similar roles in Gram-positives, though the precise targets and mechanisms of regulation may differ. The majority of bacterial life exists in a surface-associated state, with motility allowing bacteria to disseminate and colonize new environments. c-di-GMP signaling regulates flagellum biosynthesis and production of adherence factors and appears to be a primary mechanism by which bacteria sense and respond to surfaces. Ultimately, c-di-GMP influences the ability of a bacterium to alter its transcriptional program, physiology and behavior upon surface contact. This review discusses how bacteria are able to sense a surface via flagella and type IV pili, and the role of c-di-GMP in regulating the response to surfaces, with emphasis on studies of Gram-positive bacteria.

  9. Conjugative type IV secretion systems in Gram-positive bacteria.

    PubMed

    Goessweiner-Mohr, Nikolaus; Arends, Karsten; Keller, Walter; Grohmann, Elisabeth

    2013-11-01

    Bacterial conjugation presents the most important means to spread antibiotic resistance and virulence factors among closely and distantly related bacteria. Conjugative plasmids are the mobile genetic elements mainly responsible for this task. All the genetic information required for the horizontal transmission is encoded on the conjugative plasmids themselves. Two distinct concepts for horizontal plasmid transfer in Gram-positive bacteria exist, the most prominent one transports single stranded plasmid DNA via a multi-protein complex, termed type IV secretion system, across the Gram-positive cell envelope. Type IV secretion systems have been found in virtually all unicellular Gram-positive bacteria, whereas multicellular Streptomycetes seem to have developed a specialized system more closely related to the machinery involved in bacterial cell division and sporulation, which transports double stranded DNA from donor to recipient cells. This review intends to summarize the state of the art of prototype systems belonging to the two distinct concepts; it focuses on protein key players identified so far and gives future directions for research in this emerging field of promiscuous interbacterial transport.

  10. Biosynthesis of peptide signals in gram-positive bacteria.

    PubMed

    Thoendel, Matthew; Horswill, Alexander R

    2010-01-01

    Gram-positive bacteria coordinate social behavior by sensing the extracellular level of peptide signals. These signals are biosynthesized through divergent pathways and some possess unusual functional chemistry as a result of posttranslational modifications. In this chapter, the biosynthetic pathways of Bacillus intracellular signaling peptides, Enterococcus pheromones, Bacillus subtilis competence pheromones, and cyclic peptide signals from Staphylococcus and other bacteria are covered. With the increasing prevalence of the cyclic peptide signals in diverse Gram-positive bacteria, a focus on this biosynthetic mechanism and variations on the theme are discussed. Due to the importance of peptide systems in pathogenesis, there is emerging interest in quorum-quenching approaches for therapeutic intervention. The quenching strategies that have successfully blocked signal biosynthesis are also covered. As peptide signaling systems continue to be discovered, there is a growing need to understand the details of these communication mechanisms. This information will provide insight on how Gram-positives coordinate cellular events and aid strategies to target these pathways for infection treatments. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  11. Pilins in gram-positive bacteria: A structural perspective.

    PubMed

    Krishnan, Vengadesan

    2015-07-01

    Pilins or fimbrilins are a class of proteins found in bacterial surface pilus, a hair-like surface appendage. Both the Gram-negative and -positive bacteria produce pilins to assemble pili on their cell-surface for different purposes including adherence, twitching motility, conjugation, immunomodulation, biofilm formation, and electron transfer. Immunogenic properties of the pilins make them attractive vaccine candidates. The polymerized pilins play a key role in the initiation of host adhesion, which is a critical step for bacterial colonization and infection. Because of their key role in adhesion and exposure on the cell surface, targeting the pilins-mediated adhesion (anti-adhesion therapy) is also seen as a promising alternative approach for preventing and treating bacterial infections, one that may overcome their ever-increasing repertoires of resistance mechanisms. Individual pilins interact with each other non-covalently to assemble the pilus fiber with the help of associated proteins like chaperones and Usher in Gram-negative bacteria. In contrast, the pilins in Gram-positive bacteria often connect with each other covalently, with the help of sortases. Certain unique structural features present on the pilins distinguish them from one another across different bacterial strains, and these dictate their cellular targets and functions. While the structure of pilins has been extensively studied in Gram-negative pathogenic bacteria, the pilins in Gram-positive pathogenic bacteria have been in only during the last decade. Recently, the discovery of pilins in non-pathogenic bacteria, such as Lactobacillus rhamnosus GG, has received great attention, though traditionally the attention was on pathogenic bacteria. This review summarizes and discusses the current structural knowledge of pilins in Gram-positive bacteria with emphasis on those pilins which are sortase substrates.

  12. [Update on antibiotic resistance in Gram-positive bacteria].

    PubMed

    Lozano, Carmen; Torres, Carmen

    2017-01-01

    Antimicrobial resistance among Gram-positive bacteria, especially in Staphylococcus aureus, Enterococcus faecium, Enterococcus faecalis, and Streptococcus pneumoniae, is a serious threat to public health. These microorganisms have multiple resistance mechanisms to agents currently used in clinical practice. Many of these resistance mechanisms are common to all 4 of these bacterial species, but other mechanisms seem to be more specific. The prevalence and dissemination of these mechanisms varies considerably, depending on the microorganism. This review discusses the resistance mechanisms to the most clinically relevant antibiotics, with particular emphasis on the new mechanisms described for widely used antibiotics and for newer agents such as lipopeptides, lipoglycopeptides, glycylcyclines and oxazolidinones.

  13. Current and novel antibiotics against resistant Gram-positive bacteria

    PubMed Central

    Perez, Federico; Salata, Robert A; Bonomo, Robert A

    2008-01-01

    The challenge posed by resistance among Gram-positive bacteria, epitomized by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and vancomycin-intermediate and -resistant S. aureus (VISA and VRSA) is being met by a new generation of antimicrobials. This review focuses on the new β-lactams with activity against MRSA (ceftobiprole and ceftaroline) and on the new glycopeptides (oritavancin, dalbavancin, and telavancin). It will also consider the role of vancomycin in an era of existing alternatives such as linezolid, daptomycin and tigecycline. Finally, compounds in early development are described, such as iclaprim, friulimicin, and retapamulin, among others. PMID:21694878

  14. Cloacal flora isolated from wild black-bellied whistling ducks (Dendrocygna autumnalis) in Laguna La Nacha, Mexico.

    PubMed

    Aguirre, A A; Quan, T J; Cook, R S; McLean, R G

    1992-01-01

    Cloacal swabs from 110 adult black-bellied whistling ducks trapped at Laguna La Nacha, Tamaulipas, Mexico, were cultured to determine the prevalence of normal and potentially pathogenic bacteria. Twenty-five gram-negative enterobacteria and four gram-positive cocci were isolated. The most common isolates included Escherichia coli (54%), Staphylococcus spp. (29%), Streptococcus spp. (22%), Aeromonas hydrophila (15%) Enterobacter cloacae (14%), and Micrococcus sp. (14%). The implications of whistling ducks as possible reservoirs of pathogenic bacteria are discussed.

  15. Acquired inducible antimicrobial resistance in Gram-positive bacteria

    PubMed Central

    Chancey, Scott T; Zähner, Dorothea; Stephens, David S

    2012-01-01

    A major contributor to the emergence of antibiotic resistance in Gram-positive bacterial pathogens is the expansion of acquired, inducible genetic elements. Although acquired, inducible antibiotic resistance is not new, the interest in its molecular basis has been accelerated by the widening distribution and often ‘silent’ spread of the elements responsible, the diagnostic challenges of such resistance and the mounting limitations of available agents to treat Gram-positive infections. Acquired, inducible antibiotic resistance elements belong to the accessory genome of a species and are horizontally acquired by transformation/recombination or through the transfer of mobile DNA elements. The two key, but mechanistically very different, induction mechanisms are: ribosome-sensed induction, characteristic of the macrolide–lincosamide–streptogramin B antibiotics and tetracycline resistance, leading to ribosomal modifications or efflux pump activation; and resistance by cell surface-associated sensing of β-lactams (e.g., oxacillin), glycopeptides (e.g., vancomycin) and the polypeptide bacitracin, leading to drug inactivation or resistance due to cell wall alterations. PMID:22913355

  16. Controlling biofilms of gram-positive pathogenic bacteria.

    PubMed

    Abraham, Wolf-Rainer

    2006-01-01

    Many bacteria can form aggregates on interfaces, called biofilms, where they are much more protected against toxic agents such as antibiotics or antibodies. Bacteria organized in biofilms are therefore very difficult to control and often even high dosages of antibiotics cannot clear infectious biofilms. To form biofilms bacteria have to start a complex genetic program to switch from planktonic to sessile lifestyle. This starts with the determination of their cell density, a process called quorum sensing, triggered by small, water soluble molecules, so called autoinducers. From Gram-positive bacteria several small peptides are known, many of them thiolactones. More recently another group of compounds was discovered probably formed from ribose-homocysteine and the first autoinducer-II identified is a furanosyl borate diester. While small peptides are found to trigger the intraspecies communication autoinducer-II is assumed to be used for communication at the interspecies level. Taking the lead structure from these peptides several derivatives have been developed which prevent biofilm formation in many Gram-positive bacteria, including Staphylococcus aureus. Some of these compounds are already in clinical studies. In this review the different approaches to control bacterial biofilms are discussed together with the difficulties arising from the species-specificity of the autoinducers.

  17. Type IV Pili in Gram-Positive Bacteria

    PubMed Central

    Craig, Lisa

    2013-01-01

    SUMMARY Type IV pili (T4P) are surface-exposed fibers that mediate many functions in bacteria, including locomotion, adherence to host cells, DNA uptake (competence), and protein secretion and that can act as nanowires carrying electric current. T4P are composed of a polymerized protein, pilin, and their assembly apparatuses share protein homologs with type II secretion systems in eubacteria and the flagella of archaea. T4P are found throughout Gram-negative bacterial families and have been studied most extensively in certain model Gram-negative species. Recently, it was discovered that T4P systems are also widespread among Gram-positive species, in particular the clostridia. Since Gram-positive and Gram-negative bacteria have many differences in cell wall architecture and other features, it is remarkable how similar the T4P core proteins are between these organisms, yet there are many key and interesting differences to be found as well. In this review, we compare the two T4P systems and identify and discuss the features they have in common and where they differ to provide a very broad-based view of T4P systems across all eubacterial species. PMID:24006467

  18. Characterisation of thermotolerant cocci from indigenous flora of 'leben' in algerian arid area and DNA identification of atypical Lactococcus lactis strains.

    PubMed

    Bensalah, Farid; Delorme, Christine; Renault, P

    2009-08-01

    Lactic acid bacteria (LAB) are widely used in food industry and their growth performance is important for the quality of the fermented product. By combining results from conventional isolation methods and molecular investigation of 16S rRNA gene and lactococcal/enterococcal specific genes, we identify at species level catalase negative gram positive thermoresistant cocci isolated from traditional 'leben', a 24-h fermented milk in arid area of west Algeria. Forty strains phenotypically related to cocci LAB were identified as belonging to the species Lactococcus lactis ssp. lactis, Enterococcus faecalis, Enterococcus faecium, and other Enterococcus species. No Streptococcus thermophilus strain was isolated. Ten different phenotype groups were recognized, and the species content of these groups were in some cases different from the expected features usually given in genus and species descriptions. In particular, atypical lactococci, able to grow in 6.5% NaCl, at pH 9.5 and showing high resistance to thermal stresses were isolated. Lactococci, but also enterococci isolated from traditional 'leben' produced in the desert area, may be therefore of interest in milk fermentation. Further studies to assess this source of diversity within the wild microbial population should provide starter new strains for product innovation.

  19. Heterologous expression and purification of a multiheme cytochrome from a Gram-positive bacterium capable of performing extracellular respiration.

    PubMed

    Costa, N L; Carlson, H K; Coates, J D; Louro, R O; Paquete, C M

    2015-07-01

    Microbial electrochemical technologies are emerging as environmentally friendly biotechnological processes. Recently, a thermophilic Gram-positive bacterium capable of electricity production in a microbial fuel cell was isolated. Thermincola potens JR contains several multiheme c-type cytochromes that were implicated in the process of electricity production. In order to understand the molecular basis by which Gram-positive bacteria perform extracellular electron transfer, the relevant proteins need to be characterized in detail. Towards this end, a chimeric gene containing the signal peptide from Shewanella oneidensis MR-1 small tetraheme cytochrome c (STC) and the gene sequence of the target protein TherJR_0333 was constructed. This manuscript reports the successful expression of this chimeric gene in the Gram-negative bacterium Escherichia coli and its subsequent purification and characterization. This methodology opens the possibility to study other multiheme cytochromes from Gram-positive bacteria, allowing the extracellular electron transfer mechanisms of this class of organisms to be unraveled.

  20. Predominant Gram-Positive Bacteria in Human Feces: Numbers, Variety, and Persistence

    PubMed Central

    Gossling, Jennifer; Slack, John M.

    1974-01-01

    The predominant gram-positive bacteria in 47 fecal specimens from 10 healthy men were studied by microscopic and cultural counts, by the characterization and tentative identification of isolates, and by the use of fluorescein isothiocyanate (FITC)-conjugated globulins prepared using some of the isolates. Gram-positive bacteria averaged 1010.5±0.4(sd/g (wet weight) of feces with significant variation from host to host. Characterization of 865 isolates, all strict anaerobes and carbohydrate fermenters, showed 12 to 39 distinguishable strains from each host and indicated that some strains were present the full period of about 18 months. Sixty percent of the isolates belonged to one of five types, tentatively identified with five species—Bifidobacterium adolescentis, Eubacterium aerofaciens, E. rectale, Peptostreptococcus productus, and Ruminococcus bromii. There was distinct host idiosyncrasy in the pattern of estimated counts of these five types. Certain strains resembling B. adolescentis, E. aerofaciens, and P. productus, distinguished with FITC conjugates, were resident in their hosts for many months. In direct smears each strain constituted about 1% of the total bacteria. PMID:4595760

  1. New antimicrobial approaches to gram positive respiratory infections.

    PubMed

    Liapikou, Adamantia; Cilloniz, Catia; Mensa, Josep; Torres, Antonio

    2015-06-01

    Nowadays, we face growing resistance among gram-positive and gram-negative pathogens that cause respiratory infection in the hospital and in the community. The spread of penicillin- and macrolide-resistant pneumococci, Community-acquired methicillin-resistant staphylococcus aureus (Ca-MRSA), the emergence of glycopeptide-resistant staphylococci underline the need for underline the need for therapeutic alternatives. A number of new therapeutic agents, with activity against the above Gram (+) respiratory pathogens, as ceftaroline, ceftopibrole, telavancin, tedizolid have become available, either in clinical trials or have been approved for clinical use. Especially, the development of new oral antibiotics, as nemonaxacin, omadacyclin, cethromycin and solithromycin will give a solution to the lack of oral drugs for outpatient treatment. In the future the clinician needs to optimize the use of old and new antibiotics to treat gram (+) respiratory serious infections.

  2. Antibody production by the gram-positive bacterium Bacillus megaterium.

    PubMed

    Jordan, Eva; Al-Halabi, Laila; Schirrmann, Thomas; Hust, Michael

    2009-01-01

    The increasing demand for recombinant antibodies as detection reagents in research, diagnostics, and therapy requires appropriate production systems. In contrast to antibody therapies, small recombinant antibody fragments like Fab and scFv are sufficient for most applications in research and diagnostics. These antibody fragments can also be produced in bacterial hosts. Gram-negative bacteria, particularly Escherichia coli, were extensively studied for the recombinant antibody production but they showed only a limited capacity to secrete antibody fragments into the medium--a prerequisite for easy downstream processing. Gram-positive bacteria are known to efficiently secrete recombinant proteins into the medium. Recently, we demonstrated the production of scFv and scFab fragments in Bacillus megaterium. Here, we describe the process in detail from transformation of B. megaterium to production and purification of scFv fragments.

  3. Response of gram-positive bacteria to copper stress.

    PubMed

    Solioz, Marc; Abicht, Helge K; Mermod, Mélanie; Mancini, Stefano

    2010-01-01

    The Gram-positive bacteria Enterococcus hirae, Lactococcus lactis, and Bacillus subtilis have received wide attention in the study of copper homeostasis. Consequently, copper extrusion by ATPases, gene regulation by copper, and intracellular copper chaperoning are understood in some detail. This has provided profound insight into basic principles of how organisms handle copper. It also emerged that many bacterial species may not require copper for life, making copper homeostatic systems pure defense mechanisms. Structural work on copper homeostatic proteins has given insight into copper coordination and bonding and has started to give molecular insight into copper handling in biological systems. Finally, recent biochemical work has shed new light on the mechanism of copper toxicity, which may not primarily be mediated by reactive oxygen radicals.

  4. Rapid analysis of Gram-positive bacteria in water via membrane filtration coupled with nanoprobe-based MALDI-MS.

    PubMed

    Li, Shuping; Guo, Zhongxian; Wu, Hui-Fen; Liu, Ying; Yang, Zhaoguang; Woo, Chee Hoe

    2010-07-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is challenging when it is directly applied to identify bacteria in water. This study demonstrates a rapid, sensitive, and selective technique for detection of Gram-positive bacteria in water. It involves a combination of membrane filtration (MF) and vancomycin-conjugated magnetite nanoparticles (VNPs) to selectively separate and concentrate Gram-positive bacteria in tap water and reservoir water, followed by rapid analysis of the isolates using whole-cell MALDI-MS. VNPs specifically recognize cells of Gram-positive bacteria, which serves as a basis for affinity capture of target Gram-positive bacteria. A two-step procedure of surface modification of bare magnetite nanoparticles was applied to synthesize VNPs. MF prior to VNP-based magnetic separation can effectively increase the enrichment factor and detection sensitivity and reduce time-consuming culture steps and the matrix effect for analysis of bacteria in MALDI-MS. The enrichment factor for the MF-VNP technique is about 6 x 10(4). A variety of bacteria, including Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, and Enterococcus faecium, were successfully analyzed from aqueous solutions and their mixtures with Gram-negative bacteria. The optimal conditions of the VNP/MALDI-MS technique, including selection of the MALDI matrix, the choice of cell-washing solution, and the VNP concentration, were also investigated. The capture efficiencies of Gram-positive bacteria with VNPs were 26.7-33.3%. The mass variations of characteristic peaks of the captured bacteria were within +/-5 Da, which indicated good reproducibility of the proposed technique. The technique was applied to detect Gram-positive bacteria in tap water and reservoir water with an analysis time of around 2 h. The detection limit for Bacillus cereus, Enterococcus faecium, and Staphylococcus aureus was 5 x 10(2) cfu/ml for 2.0-l water samples.

  5. Contemporary potencies of minocycline and tetracycline HCL tested against Gram-positive pathogens: SENTRY Program results using CLSI and EUCAST breakpoint criteria.

    PubMed

    Jones, Ronald N; Wilson, Michael L; Weinstein, Melvin P; Stilwell, Matthew G; Mendes, Rodrigo E

    2013-04-01

    certain pathogens and utilize methods minimizing interpretive error. We conclude that EUCAST breakpoint criteria (≤0.5 or ≤1 μg/mL) represent the most conservative (better recognize strains with tet resistance mechanisms) and accurate tetracycline breakpoint guidelines for testing contemporary isolates of Gram-positive cocci. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Microarray-Based Detection of 90 Antibiotic Resistance Genes of Gram-Positive Bacteria

    PubMed Central

    Perreten, Vincent; Vorlet-Fawer, Lorianne; Slickers, Peter; Ehricht, Ralf; Kuhnert, Peter; Frey, Joachim

    2005-01-01

    A disposable microarray was developed for detection of up to 90 antibiotic resistance genes in gram-positive bacteria by hybridization. Each antibiotic resistance gene is represented by two specific oligonucleotides chosen from consensus sequences of gene families, except for nine genes for which only one specific oligonucleotide could be developed. A total of 137 oligonucleotides (26 to 33 nucleotides in length with similar physicochemical parameters) were spotted onto the microarray. The microarrays (ArrayTubes) were hybridized with 36 strains carrying specific antibiotic resistance genes that allowed testing of the sensitivity and specificity of 125 oligonucleotides. Among these were well-characterized multidrug-resistant strains of Enterococcus faecalis, Enterococcus faecium, and Lactococcus lactis and an avirulent strain of Bacillus anthracis harboring the broad-host-range resistance plasmid pRE25. Analysis of two multidrug-resistant field strains allowed the detection of 12 different antibiotic resistance genes in a Staphylococcus haemolyticus strain isolated from mastitis milk and 6 resistance genes in a Clostridium perfringens strain isolated from a calf. In both cases, the microarray genotyping corresponded to the phenotype of the strains. The ArrayTube platform presents the advantage of rapidly screening bacteria for the presence of antibiotic resistance genes known in gram-positive bacteria. This technology has a large potential for applications in basic research, food safety, and surveillance programs for antimicrobial resistance. PMID:15872258

  7. Prophylaxis, cost and effectiveness of therapy of infections caused by gram-positive organisms in neutropenic children.

    PubMed

    Schaison, G S; Decroly, F C

    1991-04-01

    Gram-positive infections are being reported with increasing frequency in children with haematological malignancies. Staphylococcus epidermidis, once considered a non-pathogenic skin contaminant, is emerging as a major cause of severe infection. However, in infants Gram-negative septicaemias are more frequent than in older children. A teicoplanin and ceftriaxone combination was assessed for use as empirical therapy of febrile episodes in neutropenic children with acute leukaemias. Of 47 patients, fever was of unknown origin in 21, and documented in 26 with 28 strains isolated; 19 Gram-positive (all sensitive to teicoplanin) and nine Gram-negative. Within 48 h, 41 patients became afebrile and the pathogen was cleared if initially present. Mean duration of treatment was 16 days. Febrile relapse occurred in 24 patients with eight documented superinfections. The need for prophylactic cover against Gram-positive organisms at the time of intravenous catheter insertion is questionable. We studied 71 patients who were randomly allocated to receive teicoplanin when the central line was inserted and if febrile, with added ceftriaxone and amikacin (arm A) or the tri-antibiotic regimen when fever occurred (arm B). In arm A a febrile episode occurred after ten days in 34/35 patients with only one Gram-positive organism isolated. In arm B a febrile episode occurred in all 36 patients after five days and ten Gram-positive strains were isolated. Those patients in arm A also received fluconazole. Amphotericin B was administered in cases of failure or relapses in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Rapid identification of Gram-positive anaerobic coccal species originally classified in the genus Peptostreptococcus by multiplex PCR assays using genus- and species-specific primers.

    PubMed

    Song, Yuli; Liu, Chengxu; McTeague, Maureen; Vu, Ann; Liu, Jia Yia; Finegold, Sydney M

    2003-07-01

    Here, a rapid and reliable two-step multiplex PCR assay for identifying 14 Gram-positive anaerobic cocci (GPAC) species originally classified in the genus Peptostreptococcus (Anaerococcus hydrogenalis, Anaerococcus lactolyticus, Anaerococcus octavius, Anaerococcus prevotii, Anaerococcus tetradius, Anaerococcus vaginalis, Finegoldia magna, Micromonas micros, Peptostreptococcus anaerobius, Peptoniphilus asaccharolyticus, Peptoniphilus harei, Peptoniphilus indolicus, Peptoniphilus ivorii and Peptoniphilus lacrimalis) is reported. Fourteen type strains representing 14 GPAC species were first identified to the genus level by multiplex PCR (multiplex PCR-G). Since three of these genera (Finegoldia, Micromonas and Peptostreptococcus) contain only a single species, F. magna, M. micros and P. anaerobius, respectively, these organisms were identified to the species level directly by using the multiplex PCR-G. Then six species of the genus Anaerococcus (A. hydrogenalis, A. lactolyticus, A. octavius, A. prevotii, A. vaginalis and A. tetradius) were further identified to the species level using multiplex PCR assays (multiplex PCR-Ia and multiplex PCR-Ib). Similarly, five species of the genus Peptoniphilus (Pn. asaccharolyticus, Pn. harei, Pn. indolicus, Pn. ivorii and Pn. lacrimalis) were identified to the species level using multiplex PCR-IIa and multiplex PCR-IIb. The established two-step multiplex PCR identification scheme was applied to the identification of 190 clinical isolates of GPAC species that had been identified previously to the species level by 16S rRNA sequencing and phenotypic tests. The identification obtained from multiplex PCR assays showed 100 % agreement with 16S rDNA sequencing identification, but only 65 % (123/190) agreement with the identification obtained by phenotypic tests. The multiplex PCR scheme established in this study is a simple, rapid and reliable method for the identification of GPAC species. It will permit a more accurate assessment of the

  9. High-level fluorescence labeling of gram-positive pathogens.

    PubMed

    Aymanns, Simone; Mauerer, Stefanie; van Zandbergen, Ger; Wolz, Christiane; Spellerberg, Barbara

    2011-01-01

    Fluorescence labeling of bacterial pathogens has a broad range of interesting applications including the observation of living bacteria within host cells. We constructed a novel vector based on the E. coli streptococcal shuttle plasmid pAT28 that can propagate in numerous bacterial species from different genera. The plasmid harbors a promoterless copy of the green fluorescent variant gene egfp under the control of the CAMP-factor gene (cfb) promoter of Streptococcus agalactiae and was designated pBSU101. Upon transfer of the plasmid into streptococci, the bacteria show a distinct and easily detectable fluorescence using a standard fluorescence microscope and quantification by FACS-analysis demonstrated values that were 10-50 times increased over the respective controls. To assess the suitability of the construct for high efficiency fluorescence labeling in different gram-positive pathogens, numerous species were transformed. We successfully labeled Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae subsp. equisimilis, Enterococcus faecalis, Enterococcus faecium, Streptococcus mutans, Streptococcus anginosus and Staphylococcus aureus strains utilizing the EGFP reporter plasmid pBSU101. In all of these species the presence of the cfb promoter construct resulted in high-level EGFP expression that could be further increased by growing the streptococcal and enterococcal cultures under high oxygen conditions through continuous aeration.

  10. Photodynamic inactivation of Gram-positive bacteria employing natural resources.

    PubMed

    Mamone, L; Di Venosa, G; Gándara, L; Sáenz, D; Vallecorsa, P; Schickinger, S; Rossetti, M V; Batlle, A; Buzzola, F; Casas, A

    2014-04-05

    The aim of this paper was to investigate a collection of plant extracts from Argentina as a source of new natural photosensitizers (PS) to be used in Photodynamic Inactivation (PDI) of bacteria. A collection of plants were screened for phototoxicity upon the Gram-positive species Staphylococcus epidermidis. Three extracts turned out to be photoactive: Solanum verbascifolium flower, Tecoma stans flower and Cissus verticillata root. Upon exposure to a light dose of 55J/cm(2), they induced 4, 2 and 3logs decrease in bacterial survival, respectively. Photochemical characterisation of S. verbascifolium extract was carried out. PDI reaction was dependent mainly on singlet oxygen and to a lesser extent, on hydroxyl radicals, through type II and I reactions. Photodegradation experiments revealed that the active principle of the extract was not particularly photolabile. It is noticeable that S. verbascifolium -PDI was more efficient under sunlight as compared to artificial light (total eradication vs. 4 logs decrease upon 120min of sunlight). The balance between oxidant and antioxidant compounds is likely to be masking or unmasking potential PS of plant extracts, but employing the crude extract, the level of photoactivity of S. verbascifolium is similar to some artificial PS upon exposure to sunlight, demonstrating that natural resources can be employed in PDI of bacteria.

  11. Resistance to bacteriocins produced by Gram-positive bacteria.

    PubMed

    Bastos, Maria do Carmo de Freire; Coelho, Marcus Lívio Varella; Santos, Olinda Cabral da Silva

    2015-04-01

    Bacteriocins are prokaryotic proteins or peptides with antimicrobial activity. Most of them exhibit a broad spectrum of activity, inhibiting micro-organisms belonging to different genera and species, including many bacterial pathogens which cause human, animal or plant infections. Therefore, these substances have potential biotechnological applications in either food preservation or prevention and control of bacterial infectious diseases. However, there is concern that continuous exposure of bacteria to bacteriocins may select cells resistant to them, as observed for conventional antimicrobials. Based on the models already investigated, bacteriocin resistance may be either innate or acquired and seems to be a complex phenomenon, arising at different frequencies (generally from 10(-9) to 10(-2)) and by different mechanisms, even amongst strains of the same bacterial species. In the present review, we discuss the prevalence, development and molecular mechanisms involved in resistance to bacteriocins produced by Gram-positive bacteria. These mechanisms generally involve changes in the bacterial cell envelope, which result in (i) reduction or loss of bacteriocin binding or insertion, (ii) bacteriocin sequestering, (iii) bacteriocin efflux pumping (export) and (iv) bacteriocin degradation, amongst others. Strategies that can be used to overcome this resistance are also addressed.

  12. Multifunctional cellulose beads and their interaction with gram positive bacteria.

    PubMed

    Blachechen, Leandro S; Fardim, Pedro; Petri, Denise F S

    2014-09-08

    Cellulose beads with ∼3 mm of diameter and high circularity were obtained by dripping cellulose solutions (5, 6, and 7 wt %) dissolved in NaOH7%/urea12%, into HCl 2 M coagulation bath. Carboxylic groups were generated on beads surface through NaClO/NaClO2/TEMPO oxidation method, achieving total charge density of ∼0.77 mmol/g. Pristine (CB) and oxidized (OCB) beads were characterized by means of optical images analyses, scanning electron microscopy (SEM) and compression tests. Both types of beads, CB and OCB, were used as adsorbent for poly(4-vinyl-N-pentylpyridinium) bromide, QPVP-C5, a bactericidal agent. The adsorption of QPVP-C5 on CB and OCB was evaluated by means of FTIR-ATR, UV-vis, CHN elemental analyses, and X-ray photoelectron spectroscopy (XPS). The adsorbed amount of QPVP-C5 was remarkably higher on OCB than on CB due to ionic interactions. Desorption was less than 5%. The interaction between neat OCB or OCB coated and two different amounts of QPVP-C5 and Gram-positive bacteria Micrococcus luteus was assessed by changes in turbidimetry, SEM, and elemental analyses. Bacteria adsorbed on the surface of neat OCB and weakly QPVP-C5 coated OCB due to hydrogen bonding or ion-dipole interaction. Notorious bactericidal action was observed for OCB samples coated with large amount of QPVP-C5.

  13. Streptococcus mutans: a new Gram-positive paradigm?

    PubMed

    Lemos, José A; Quivey, Robert G; Koo, Hyun; Abranches, Jacqueline

    2013-03-01

    Despite the enormous contributions of the bacterial paradigms Escherichia coli and Bacillus subtilis to basic and applied research, it is well known that no single organism can be a perfect representative of all other species. However, given that some bacteria are difficult, or virtually impossible, to cultivate in the laboratory, that some are recalcitrant to genetic and molecular manipulation, and that others can be extremely dangerous to manipulate, the use of model organisms will continue to play an important role in the development of basic research. In particular, model organisms are very useful for providing a better understanding of the biology of closely related species. Here, we discuss how the lifestyle, the availability of suitable in vitro and in vivo systems, and a thorough understanding of the genetics, biochemistry and physiology of the dental pathogen Streptococcus mutans have greatly advanced our understanding of important areas in the field of bacteriology such as interspecies biofilms, competence development and stress responses. In this article, we provide an argument that places S. mutans, an organism that evolved in close association with the human host, as a novel Gram-positive model organism.

  14. Regulation of Apoptosis by Gram-Positive Bacteria

    PubMed Central

    Ulett, Glen C.; Adderson, Elisabeth E.

    2008-01-01

    Apoptosis, or programmed cell death (PCD), is an important physiological mechanism, through which the human immune system regulates homeostasis and responds to diverse forms of cellular damage. PCD may also be involved in immune counteraction to microbial infection. Over the past decade, the amount of research on bacteria-induced PCD has grown tremendously, and the implications of this mechanism on immunity are being elucidated. Some pathogenic bacteria actively trigger the suicide response in critical lineages of leukocytes that orchestrate both the innate and adaptive immune responses; other bacteria proactively prevent PCD to benefit their own survival and persistence. Currently, the microbial virulence factors, which represent the keys to unlocking the suicide response in host cells, are a primary focus of this field. In this review, we discuss these bacterial “apoptosis regulatory molecules” and the apoptotic events they either trigger or prevent, the host target cells of this regulatory activity, and the possible ramifications for immunity to infection. Gram-positive pathogens including Staphylococcus, Streptococcus, Bacillus, Listeria, and Clostridia species are discussed as important agents of human infection that modulate PCD pathways in eukaryotic cells. PMID:19081777

  15. Saponin promotes rapid identification and antimicrobial susceptibility profiling of Gram-positive and Gram-negative bacteria in blood cultures with the Vitek 2 system.

    PubMed

    Lupetti, A; Barnini, S; Morici, P; Ghelardi, E; Nibbering, P H; Campa, M

    2013-04-01

    The rapid identification and antimicrobial susceptibility testing (AST) of bacteria in clinical blood cultures is crucial to optimise antimicrobial therapy. A previous study involving small sample numbers revealed that the addition of saponin to blood cultures, further referred to as the new method, shortened considerably the turn-around time for the identification and AST of Gram-positive cocci as compared to the current method involving an overnight subculture. Here, we extend previous results and compare the identification and AST of blood cultures containing Gram-negative bacilli by the new and current methods. The identification and AST of 121 Gram-positive and 109 Gram-negative bacteria in clinical monomicrobial blood cultures by the new and current methods and, in the case of Gram-negative bacilli, by direct (no additions) inoculation into an automated system (rapid method) was assessed using the Vitek 2 system. Discrepancies between the results obtained with the different methods were solved by manual methods. The new method correctly identified 88 % of Gram-positive and 98 % of Gram-negative bacteria, and the rapid method correctly identified 94 % of Gram-negative bacteria. The AST for all antimicrobials by the new method were concordant with the current method for 55 % and correct for an additional 9 % of Gram-positive bacteria, and concordant with the current method for 62 % and correct for an additional 21 % of Gram-negative bacilli. The AST by the rapid method was concordant with the current method for 62 % and correct for an additional 12 % of Gram-negative bacilli. Together, saponin-treated monomicrobial blood cultures allow rapid and reliable identification and AST of Gram-positive and Gram-negative bacteria.

  16. Novel Antimicrobial Peptides That Inhibit Gram Positive Bacterial Exotoxin Synthesis

    PubMed Central

    Merriman, Joseph A.; Nemeth, Kimberly A.; Schlievert, Patrick M.

    2014-01-01

    Gram-positive bacteria, such as Staphylococcus aureus, cause serious human illnesses through combinations of surface virulence factors and secretion of exotoxins. Our prior studies using the protein synthesis inhibitor clindamycin and signal transduction inhibitors glycerol monolaurate and α-globin and β-globin chains of hemoglobin indicate that their abilities to inhibit exotoxin production by S. aureus are separable from abilities to inhibit growth of the organism. Additionally, our previous studies suggest that inhibition of exotoxin production, in absence of ability to kill S. aureus and normal flora lactobacilli, will prevent colonization by pathogenic S. aureus, while not interfering with lactobacilli colonization. These disparate activities may be important in development of novel anti-infective agents that do not alter normal flora. We initiated studies to explore the exotoxin-synthesis-inhibition activity of hemoglobin peptides further to develop potential agents to prevent S. aureus infections. We tested synthesized α-globin chain peptides, synthetic variants of α-globin chain peptides, and two human defensins for ability to inhibit exotoxin production without significantly inhibiting S. aureus growth. All of these peptides were weakly or not inhibitory to bacterial growth. However, the peptides were inhibitory to exotoxin production with increasing activity dependent on increasing numbers of positively-charged amino acids. Additionally, the peptides could be immobilized on agarose beads or have amino acid sequences scrambled and still retain exotoxin-synthesis-inhibition. The peptides are not toxic to human vaginal epithelial cells and do not inhibit growth of normal flora L. crispatus. These peptides may interfere with plasma membrane signal transduction in S. aureus due to their positive charges. PMID:24748386

  17. Novel antimicrobial peptides that inhibit gram positive bacterial exotoxin synthesis.

    PubMed

    Merriman, Joseph A; Nemeth, Kimberly A; Schlievert, Patrick M

    2014-01-01

    Gram-positive bacteria, such as Staphylococcus aureus, cause serious human illnesses through combinations of surface virulence factors and secretion of exotoxins. Our prior studies using the protein synthesis inhibitor clindamycin and signal transduction inhibitors glycerol monolaurate and α-globin and β-globin chains of hemoglobin indicate that their abilities to inhibit exotoxin production by S. aureus are separable from abilities to inhibit growth of the organism. Additionally, our previous studies suggest that inhibition of exotoxin production, in absence of ability to kill S. aureus and normal flora lactobacilli, will prevent colonization by pathogenic S. aureus, while not interfering with lactobacilli colonization. These disparate activities may be important in development of novel anti-infective agents that do not alter normal flora. We initiated studies to explore the exotoxin-synthesis-inhibition activity of hemoglobin peptides further to develop potential agents to prevent S. aureus infections. We tested synthesized α-globin chain peptides, synthetic variants of α-globin chain peptides, and two human defensins for ability to inhibit exotoxin production without significantly inhibiting S. aureus growth. All of these peptides were weakly or not inhibitory to bacterial growth. However, the peptides were inhibitory to exotoxin production with increasing activity dependent on increasing numbers of positively-charged amino acids. Additionally, the peptides could be immobilized on agarose beads or have amino acid sequences scrambled and still retain exotoxin-synthesis-inhibition. The peptides are not toxic to human vaginal epithelial cells and do not inhibit growth of normal flora L. crispatus. These peptides may interfere with plasma membrane signal transduction in S. aureus due to their positive charges.

  18. [Evaluation of API Coryne System, version 2.0, for diphteroid gram-positive rods identification with clinical relevance].

    PubMed

    Almuzara, M N; De Mier, C; Rodríguez, C R; Famiglietti, A M R; Vay, C A

    2006-01-01

    The ability of the API Coryne system, version 2.0, to identify 178 strains of gram-positive rods was evaluated. Seventy eight isolates belonged to genus Corynebacterium and one hundred to related genera, all strains were isolated from clinical samples at the Laboratory of Bacteriology, Hospital de Clínicas José de San Martin (UBA) between 1995 and 2004. The isolates were identified according to von Graevenitz and Funke's scheme. One hundred and sixty two out of 178 strains (91%) were correctly identified at genus and species level (IC95 = 85.6-94.6), in 44 of them (24.7%) additional tests were needed to final identification. Sixteen strains (9%) were not correctly identified (IC95 = 5.4-14.4); none of the 178 strains remained unidentified. The API Coryne system, version 2.0, is useful to identify the majority of Cory-nebacterium species with clinical relevance: Corynebacterium jeikeium, Corynebacterium urealyticum, Corynebacterium striatum, Corynebacterium pseudodiphtheriticum, Corynebacterium amycolatum and related species such as Arcanobacterium haemolyticum, Dermabacter hominis, Listeria monocytogenes, among others. Nevertheless for yellow-pigmented diphteroid gram-positive rods (Aureobacterium spp., Leifsonia aquatica, Microbacterium spp. and Cellulomonas spp.) and for acid fast gram-positive rods (Rhodococcus, Gordonia, Tsukamurella and Nocardia) the identification usefulness the system is limited.

  19. Gepotidacin (GSK2140944) In Vitro Activity against Gram-Positive and Gram-Negative Bacteria.

    PubMed

    Flamm, R K; Farrell, D J; Rhomberg, P R; Scangarella-Oman, N E; Sader, H S

    2017-07-01

    Gepotidacin is a first-in-class, novel triazaacenaphthylene antibiotic that inhibits bacterial DNA replication and has in vitro activity against susceptible and drug-resistant pathogens. Reference in vitro methods were used to investigate the MICs and minimum bactericidal concentrations (MBCs) of gepotidacin and comparator agents for Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli Gepotidacin in vitro activity was also evaluated by using time-kill kinetics and broth microdilution checkerboard methods for synergy testing and for postantibiotic and subinhibitory effects. The MIC90 of gepotidacin for 50 S. aureus (including methicillin-resistant S. aureus [MRSA]) and 50 S. pneumoniae (including penicillin-nonsusceptible) isolates was 0.5 μg/ml, and for E. coli (n = 25 isolates), it was 4 μg/ml. Gepotidacin was bactericidal against S. aureus, S. pneumoniae, and E. coli, with MBC/MIC ratios of ≤4 against 98, 98, and 88% of the isolates tested, respectively. Time-kill curves indicated that the bactericidal activity of gepotidacin was observed at 4× or 10× MIC at 24 h for all of the isolates. S. aureus regrowth was observed in the presence of gepotidacin, and the resulting gepotidacin MICs were 2- to 128-fold higher than the baseline gepotidacin MICs. Checkerboard analysis of gepotidacin combined with other antimicrobials demonstrated no occurrences of antagonism with agents from multiple antimicrobial classes. The most common interaction when testing gepotidacin was indifference (fractional inhibitory concentration index of >0.5 to ≤4; 82.7% for Gram-positive isolates and 82.6% for Gram-negative isolates). The postantibiotic effect (PAE) of gepotidacin was short when it was tested against S. aureus (≤0.6 h against MRSA and MSSA), and the PAE-sub-MIC effect (SME) was extended (>8 h; three isolates at 0.5× MIC). The PAE of levofloxacin was modest (0.0 to 2.4 h), and the PAE-SME observed varied from 1.2 to >9 h at 0.5× MIC. These in vitro

  20. Active infective endocarditis due to Erysipelothrix rhusiopathiae: zoonosis caused by vancomycin-resistant gram-positive rod.

    PubMed

    Miura, Takashi; Hashizume, Koji; Ariyoshi, Tsuneo; Miwa, Takashi; Furumoto, Akitsugu; Izumida, Mai; Yanagihara, Katsunori; Eishi, Kiyoyuki

    2013-02-01

    A 42-year-old female who was a voluntary worker in a school for handicapped children was referred to us for surgery for active infective endocarditis. Trans-esophageal echocardiography showed 2 large mobile vegetations on the aortic valve and severe aortic regurgitation. Aortic valve replacement was performed to prevent septic embolism and deterioration of congestive heart failure. The empiric therapy with vancomycin, ampicillin, and gentamycin was initiated because a pathogen was not identified. But Erysipelothrix rhusiopathiae (gram-positive rod) was isolated on the 4th day after surgery. The target therapy with penicillin G and clindamycin was started and continued for 4 weeks after surgery. The inflammatory parameters improved steadily and the patient was discharged on the 36th day after surgery. Infective endocarditis due to gram-positive rods can be easily mistaken for streptococci or dismissed as a skin contamination. But, E. rhusiopathiae endocarditis should be considered in the differential diagnosis.

  1. The ability of electrochemical oxidation with a BDD anode to inactivate Gram-negative and Gram-positive bacteria in low conductivity sulfate medium.

    PubMed

    Bruguera-Casamada, Carmina; Sirés, Ignasi; Prieto, María J; Brillas, Enric; Araujo, Rosa M

    2016-11-01

    The disinfection of 100 mL of synthetic water containing 7 mM Na2SO4 with 10(6) CFU mL(-1) of either Gram-negative or Gram-positive bacteria has been studied by electrochemical oxidation. The electrolytic cell was a stirred tank reactor equipped with a boron-doped diamond (BDD) anode and a stainless steel cathode and the trials were performed at acidic and neutral pH, at 33.3 mA cm(-2) and 25 °C. Reactive oxygen species, pre-eminently hydroxyl radicals, were efficiently produced in both media from water oxidation at the BDD anode and the bacteria concentration was reduced by ≥ 5 log units after 60 min of electrolysis, thus constituting a good chlorine-free disinfection treatment. All the inactivation kinetics were described by a logistic model, with no significant statistical differences between acidic and neutral suspensions. The electrochemical disinfection with BDD was very effective for Gram-negative bacilli like Escherichia coli and Pseudomonas aeruginosa and Gram-positive ones like Bacillus atrophaeus, whereas the Gram-positive cocci Staphylococcus aureus and Enterococcus hirae were more resistant. Thus, the latter organisms are a better choice than E. coli as process indicators. Scanning electron microscopy highlighted a transition from initial cells with standard morphology supported on clean filters to inactivated cells with a highly altered morphology lying on dirty filters with plenty of cellular debris. Larger damage was observed for Gram-negative cells compared to Gram-positive ones. The inactivation effect could then be related to the chemical composition of the outer layers of the cell structure along with the modification of the transmembrane potentials upon current passage.

  2. Biochemical characterization of Gram-positive and Gram-negative plant-associated bacteria with micro-Raman spectroscopy.

    PubMed

    Paret, Mathews L; Sharma, Shiv K; Green, Lisa M; Alvarez, Anne M

    2010-04-01

    Raman spectra of Gram-positive and Gram-negative plant bacteria have been measured with micro-Raman spectrometers equipped with 785 and 514.5 nm lasers. The Gram-positive bacteria Microbacterium testaceum, Paenibacillus validus, and Clavibacter michiganensis subsp. michiganensis have strong carotenoid bands in the regions 1155-1157 cm(-1) and 1516-1522 cm(-1) that differentiate them from other tested Gram-negative bacteria. In the Raman spectrum of Gram-positive bacteria Bacillus megaterium excited with 785 nm laser, the Raman bands at 1157 and 1521 cm(-1) are weak in intensity compared to other Gram-positive bacteria, and these bands did not show significant resonance Raman enhancement in the spectrum recorded with 514.5 nm laser excitation. The Gram-positive bacteria could be separated from each other based on the bands associated with the in-phase C=C (v(1)) vibrations of the polyene chain of carotenoids. None of the Gram-negative bacteria tested had carotenoid bands. The bacteria in the genus Xanthomonas have a carotenoid-like pigment, xanthomonadin, identified in Xanthomonas axonopodis pv. dieffenbachiae, and it is a unique Raman marker for the bacteria. The representative bands for xanthomonadin were the C-C stretching (v(2)) vibrations of the polyene chain at 1135-1136 cm(-1) and the in-phase C=C (v(1)) vibrations of the polyene chain at 1529-1531 cm(-1), which were distinct from the carotenoid bands of other tested bacteria. The tyrosine peak in the region 1170-1175 cm(-1) was the only other marker present in Gram-negative bacteria that was absent in all tested Gram-positives. A strong-intensity exopolysaccharide-associated marker at 1551 cm(-1) is a distinguishable feature of Enterobacter cloacae. The Gram-negative Agrobacterium rhizogenes and Ralstonia solanacearum were differentiated from each other and other tested bacteria on the basis of presence or absence and relative intensities of peaks. The principal components analysis (PCA) of the spectra

  3. Cultivation of aerobic chemoorganotrophic proteobacteria and gram-positive bacteria from a hot spring microbial mat.

    PubMed

    Nold, S C; Kopczynski, E D; Ward, D M

    1996-11-01

    The diversity of aerobic chemoorganotrophic bacteria inhabiting the Octopus Spring cyanobacterial mat community (Yellowstone National Park) was examined by using serial-dilution enrichment culture and a variety of enrichment conditions to cultivate the numerically significant microbial populations. The most abundant bacterial populations cultivated from dilutions to extinction were obtained from enrichment flasks which contained 9.0 x 10(2) primary producer (Synechococcus spp.) cells in the inoculum. Two isolates exhibited 16S rRNA nucleotide sequences typical of beta-proteobacteria. One of these isolates contained a 16S rRNA sequence identical to a sequence type previously observed in the mat by molecular retrieval techniques. Both are distantly related to a new sequence directly retrieved from the mat and contributed by a beta-proteobacterial community member. Phenotypically diverse gram-positive isolates genetically similar to Bacillus flavothermus were obtained from a variety of dilutions and enrichment types. These isolates exhibited identical 16S rRNA nucleotide sequences through a variable region of the molecule. Of the three unique sequences observed, only one had been previously retrieved from the mat, illustrating both the inability of the cultivation methods to describe the composition of a microbial community and the limitations of the ability of molecular retrieval techniques to describe populations which may be less abundant in microbial communities.

  4. Genetic determinants of antimicrobial resistance in Gram positive bacteria from organic foods.

    PubMed

    Fernández-Fuentes, Miguel Angel; Abriouel, Hikmate; Ortega Morente, Elena; Pérez Pulido, Rubén; Gálvez, Antonio

    2014-02-17

    Bacterial biocide resistance is becoming a matter of concern. In the present study, a collection of biocide-resistant, Gram-positive bacteria from organic foods (including 11 isolates from genus Bacillus, 25 from Enterococcus and 10 from Staphylococcus) were analyzed for genes associated to biocide resistance efflux pumps and antibiotic resistance. The only qac-genes detected were qacA/B (one Bacillus cereus isolate) and smr (one B. cereus and two Staphylococcus saprophyticus isolates). Efflux pump genes efrA and efrB genes were detected in Staphylococcus (60% of isolates), Bacillus (54.54%) and Enterococcus (24%); sugE was detected in Enterococcus (20%) and in one Bacillus licheniformis; mepA was detected in Staphylococcus (60%) and in one Enterococcus isolate (which also carried mdeA), and norE gene was detected only in one Enterococcus faecium and one S. saprophyticus isolate. An amplicon for acrB efflux pump was detected in all but one isolate. When minimal inhibitory concentrations (MICs) were determined, it was found that the addition of reserpine reduced the MICs by eight fold for most of the biocides and isolates, corroborating the role of efflux pumps in biocide resistance. Erythromycin resistance gene ermB was detected in 90% of Bacillus isolates, and in one Staphylococcus, while ereA was detected only in one Bacillus and one Staphyloccus, and ereB only in one Staphylococcus. The ATP-dependent msrA gene (which confers resistance to macrolides, lincosamides and type B streptogramins) was detected in 60% of Bacillus isolates and in all staphylococci, which in addition carried msrB. The lincosamide and streptogramin A resistance gene lsa was detected in Staphylococcus (40%), Bacillus (27.27%) and Enterococcus (8%) isolates. The aminoglycoside resistance determinant aph (3_)-IIIa was detected in Staphylococcus (40%) and Bacillus (one isolate), aph(2_)-1d in Bacillus (27.27%) and Enterococcus (8%), aph(2_)-Ib in Bacillus (one isolate), and the bifunctional aac

  5. Sample preparation of Gram-positive bacteria for identification by matrix assisted laser desorption/ionization time-of-flight.

    PubMed

    Smole, Sandra C; King, Lisa A; Leopold, Peter E; Arbeit, Robert D

    2002-02-01

    A new sample preparation method was developed for fresh, whole-cell Gram-positive bacteria to be analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI ToF MS). With fresh, whole-cell Gram-negative bacteria of the Enterobacteriaceae family, we had previously achieved spectra consisting of >50 peaks and mass ranges of 2-25 kDa. Because similar spectral quantity could not be achieved for Gram-positive bacteria, using this same protocol, we investigated an alternative approach that focuses on the thick peptidoglycan layer of the cell wall. Gram-positive bacteria were incubated with 0.05-0.5 mg/ml lysozyme for 30 min prior to being analyzed by MALDI ToF MS. Lysozyme is an enzymatically stable, 14-kDa protein that specifically cleaves between peptidoglycan disaccharide subunits. A significant increase in overall number of peaks (>50) in the 2-14 kDa range was observed without interference from the presence of lysozyme. We show that for four different species (Staphylococcus aureus, S. haemolyticus, Streptococcus pyogenes, and S. agalactiae) reproducible subset of peaks were found within spectra from a reference strain and two unrelated clinical isolates. The data suggests that this sample preparation may be useful for increasing the overall number of peaks within spectra for subsequent development of bacterial identification strategies.

  6. Isolation and identification of culturable halophilic bacteria with producing hydrolytic enzyme from Incheh Broun hypersaline wetland in Iran.

    PubMed

    Zarparvar, P; Amoozegar, M A; Babavalian, H; Reza Fallahian, M; Tebyanian, H; Shakeri, F

    2016-10-31

    Incheh Broun hypersaline wetland is located near the border of Turkmenistan in thenorth of Iran. This wetland is notable because of salinity (280g/l) and alteration in pH range (2.8 to 6.8). Eastern part of wetland is affected by wastewater of iodine extraction factory.  Samples were taken from soil, water and salt. Totally, 400 bacterial strains were isolated of which 194 strains were Gram-positive bacilli, 184 strains were Gram-negative rod and 22 strains were Gram-positive cocci. According to phylogenetic analysis of 16S rRNA, selected strains were placed in three taxonomic phyla including Firmicutes, Actinobacteria and Gammaproteobacteria. Optimum growth was evaluated for salt and 22 strains were found to be moderate halophile and 33 strains were halotolerant. Production of lipase, amylase, gelatinase and protease was examined. Gram-positive bacilli were the main producers of hydrolytic enzymes. Gelatinase and protease were the most frequent enzymes. Gram-positive cocci were the main producers of lipase but they didn't produce amylase.

  7. Chemoinformatics for medicinal chemistry: in silico model to enable the discovery of potent and safer anti-cocci agents.

    PubMed

    Speck-Planche, Alejandro; Cordeiro, Maria Natália Dias Soeiro

    2014-01-01

    Gram-positive cocci are increasingly antibiotic-resistant bacteria responsible for causing serious diseases. Chemoinformatics can help to rationalize the discovery of more potent and safer antibacterial drugs. We have developed a chemoinformatic model for simultaneous prediction of anti-cocci activities, and profiles involving absorption, distribution, metabolism, elimination and toxicity (ADMET). A dataset containing 48,874 cases from many different chemicals assayed under dissimilar experimental conditions was created. The best model displayed accuracies around 93% in both training and prediction (test) sets. Quantitative contributions of several fragments to the biological effects were calculated and analyzed. Multiple biological effects of the investigational drug JNJ-Q2 were correctly predicted. Our chemoinformatic model can be used as powerful tool for virtual screening of promising anti-cocci agents.

  8. Antibacterial Efficacy of Eravacycline In Vivo against Gram-Positive and Gram-Negative Organisms

    PubMed Central

    Monogue, Marguerite L.; Hamada, Yukihiro

    2016-01-01

    Members of the tetracycline class are frequently classified as bacteriostatic. However, recent findings have demonstrated an improved antibacterial killing profile, often achieving ≥3 log10 bacterial count reduction, when such antibiotics have been given for periods longer than 24 h. We aimed to study this effect with eravacycline, a novel fluorocycline, given in an immunocompetent murine thigh infection model over 72 h against two methicillin-resistant Staphylococcus aureus (MRSA) isolates (eravacycline MICs = 0.03 and 0.25 μg/ml) and three Enterobacteriaceae isolates (eravacycline MICs = 0.125 to 0.25 μg/ml). A humanized eravacycline regimen, 2.5 mg/kg of body weight given intravenously (i.v.) every 12 h (q12h), demonstrated progressively enhanced activity over the 72-h study period. A cumulative dose response in which bacterial density was reduced by more than 3 log10 CFU at 72 h was noted over the study period in the two Gram-positive isolates, and eravacycline performed similarly to comparator antibiotics (tigecycline, linezolid, and vancomycin). A cumulative dose response with eravacycline and comparators (tigecycline and meropenem) over the study period was also observed in the Gram-negative isolates, although more variability in bacterial killing was observed for all antibacterial agents. Overall, a bacterial count reduction of ≥3 log was achieved in one of the three isolates with both eravacycline and tigecycline, while meropenem achieved a similar endpoint against two of the three isolates. Bactericidal activity is typically defined in vitro over 24 h; however, extended regimen studies in vivo may demonstrate an improved correlation with clinical outcomes by better identification of antimicrobial effects. PMID:27353265

  9. Multistep Resistance Development Studies of Ceftaroline in Gram-Positive and -Negative Bacteria▿

    PubMed Central

    Clark, Catherine; McGhee, Pamela; Appelbaum, Peter C.; Kosowska-Shick, Klaudia

    2011-01-01

    Ceftaroline, the active component of the prodrug ceftaroline fosamil, is a novel broad-spectrum cephalosporin with bactericidal activity against Gram-positive and -negative isolates. This study evaluated the potential for ceftaroline and comparator antibiotics to select for clones of Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecalis with elevated MICs. S. pneumoniae and S. pyogenes isolates in the present study were highly susceptible to ceftaroline (MIC range, 0.004 to 0.25 μg/ml). No streptococcal strains yielded ceftaroline clones with increased MICs (defined as an increase in MIC of >4-fold) after 50 daily passages. Ceftaroline MICs for H. influenzae and M. catarrhalis were 0.06 to 2 μg/ml for four strains and 8 μg/ml for a β-lactamase-positive, efflux-positive H. influenzae with a mutation in L22. One H. influenzae clone with an increased ceftaroline MIC (quinolone-resistant, β-lactamase-positive) was recovered after 20 days. The ceftaroline MIC for this isolate increased 16-fold, from 0.06 to 1 μg/ml. MICs for S. aureus ranged from 0.25 to 1 μg/ml. No S. aureus isolates tested with ceftaroline had clones with increased MIC (>4-fold) after 50 passages. Two E. faecalis isolates tested had ceftaroline MICs increased from 1 to 8 μg/ml after 38 days and from 4 to 32 μg/ml after 41 days, respectively. The parental ceftaroline MIC for the one K. pneumoniae extended-spectrum β-lactamase-negative isolate tested was 0.5 μg/ml and did not change after 50 daily passages. PMID:21343467

  10. Mechanisms of action of newer antibiotics for Gram-positive pathogens.

    PubMed

    Hancock, Robert Ew

    2005-04-01

    Certain Gram-positive bacteria, including meticillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, and quinolone-resistant Streptococcus pneumoniae have achieved the status of "superbugs", in that there are few or no antibiotics available for therapy against these pathogens. Only a few classes of novel antibiotics have been introduced in the past 40 years, and all since 1999, including the streptogramin combination quinupristin/dalfopristin (Synercid), the oxazolidinone linezolid, and the lipopeptide daptomycin. This review discusses the mechanisms of antibiotic action against Gram-positive pathogens, and resistance counter-mechanisms developed by Gram-positive bacteria, with emphasis on the newer agents.

  11. Thermophilic Gram-Positive Biocatalysts for Biomass Conversion to Ethanol

    SciTech Connect

    Shanmugam, K.T.; Ingram, L.O.; Maupin-Furlow, J.A.; Preston, J.F.; Aldrich, H.C.

    2003-12-01

    Production of energy from renewable sources is receiving increased attention due to the finite nature of fossil fuels and the environmental impact associated with the continued large scale use of fossil energy sources. Biomass, a CO2-neutral abundant resource, is an attractive alternate source of energy. Biomass-derived sugars, such as glucose, xylose, and other minor sugars, can be readily fermented to fuel ethanol and commodity chemicals. Extracellular cellulases produced by fungi are commercially developed for depolymerization of cellulose in biomass to glucose for fermentation by appropriate biocatalysts in a simultaneous saccharification and fermentation (SSF) process. Due to the differences in the optimum conditions for the activity of the fungal cellulases and the growth and fermentation characteristics of the current industrial biocatalysts, SSF of cellulose is envisioned at conditions that are not optimal for the fungal cellulase activity leading to higher than required cost of cellulase in SSF. We have isolated bacterial biocatalysts whose growth and fermentation requirements match the optimum conditions for commercial fungal cellulase activity (pH 5.0 and 50 deg. C). These isolates fermented both glucose and xylose, major components of cellulose and hemicellulose, respectively, to L(+)-lactic acid. Xylose was metabolized through the pentose-phosphate pathway by these organisms as evidenced by the fermentation profile and analysis of the fermentation products of 13C1-xylose by NMR. As expected for the metabolism of xylose by the pentose-phosphate pathway, 13C-lactate accounted for more than 90% of the total 13C-labeled products. All three strains fermented crystalline cellulose to lactic acid with the addition of fungal cellulase (Spezyme CE) (SSF) at an optimum of about 10 FPU/g cellulose. These isolates also fermented cellulose and sugar cane bagasse hemicellulose acid hydrolysate simultaneously. Based on fatty acid profile and 16S rRNA sequence, these

  12. Antimicrobial susceptibility of non-enterococcal intrinsic glycopeptide-resistant Gram-positive organisms.

    PubMed

    Vay, Carlos; Cittadini, Roxana; Barberis, Claudia; Hernán Rodríguez, Carlos; Perez Martínez, Herminia; Genero, Fabiana; Famiglietti, Angela

    2007-02-01

    Non-enterococcal Gram-positive bacteria that are intrinsically vancomycin-resistant have been infrequently isolated in association with serious infections. However, well-documented infections have lately been reported with increasing frequency. Because these organisms may be pathogens, we tested the MICs of 19 antimicrobial agents by the agar dilution method for predicting susceptibility. The activity of these antimicrobial agents was assessed against 28 strains (Lactobacillus rhamnosus, 6; Lactobacillus acidophilus, 1; Lactobacillus casei, 1; Lactobacillus fermentum, 2; Lactobacillus brevis, 1; Lactobacillus plantarum, 1; Weissella confusa, 2; Leuconostoc mesenteroides, 7; Leuconostoc lactis, 4; Pediococcus acidilactici, 2; Pediococcus pentosaceus, 1), isolated from clinical specimens in an Argentinian university hospital from 1997 to 2003. The MICs of penicillin for 67% of the Lactobacillus strains and 100% of the Leuconostoc spp. and Pediococcus spp. strains tested were in the 0.25-2 microg/mL range. Erythromycin was the most active antimicrobial overall. Multiresistance was observed in 2 strains (Lactobacillus rhamnosus, 1; Lactobacillus plantarum, 1).

  13. Antibacterial activity of oregano (Origanum vulgare Linn.) against gram positive bacteria.

    PubMed

    Saeed, Sabahat; Tariq, Perween

    2009-10-01

    The present investigation is focused on antibacterial potential of infusion, decoction and essential oil of oregano (Origanum vulgare) against 111 Gram-positive bacterial isolates belonging to 23 different species related to 3 genera. Infusion and essential oil exhibited antibacterial activity against Staphylococcus saprophyticus, S. aureus, Micrococcus roseus, M. kristinae, M. nishinomiyaensis, M. lylae, M. luteus, M. sedentarius, M. varians, Bacillus megaterium, B. thuringiensis, B. alvei, B. circulans, B. brevis, B. coagulans, B. pumilus, B. laterosporus, B. polymyxa, B. macerans, B. subtilis, B. firmus, B. cereus and B. lichiniformis. The infusion exhibited maximum activity against B. laterosporus (17.5 mm mean zone of inhibition+/-1.5 Standard deviation) followed by B. polymyxa (17.0 mm+/-2.0 SD) and essential oil of oregano exhibited maximum activity against S. saprophyticus (16.8 mm+/-1.8 SD) followed by B. circulans (14.5 mm+/-0.5 SD). While all these tested isolates were found resistant to decoction of oregano.

  14. Distinction of Gram-positive and -negative bacteria using a colorimetric microbial viability assay based on the reduction of water-soluble tetrazolium salts with a selection medium.

    PubMed

    Tsukatani, Tadayuki; Suenaga, Hikaru; Higuchi, Tomoko; Shiga, Masanobu; Noguchi, Katsuya; Matsumoto, Kiyoshi

    2011-01-01

    Bacteria are fundamentally divided into two groups: Gram-positive and Gram-negative. Although the Gram stain and other techniques can be used to differentiate these groups, some issues exist with traditional approaches. In this study, we developed a method for differentiating Gram-positive and -negative bacteria using a colorimetric microbial viability assay based on the reduction of the tetrazolium salt {2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium, monosodium salt} (WST-8) via 2-methyl-1,4-napthoquinone with a selection medium. We optimized the composition of the selection medium to allow the growth of Gram-negative bacteria while inhibiting the growth of Gram-positive bacteria. When the colorimetric viability assay was carried out in a selection medium containing 0.5µg/ml crystal violet, 5.0 µg/ml daptomycin, and 5.0µg/ml vancomycin, the reduction in WST-8 by Gram-positive bacteria was inhibited. On the other hand, Gram-negative bacteria produced WST-8-formazan in the selection medium. The proposed method was also applied to determine the Gram staining characteristics of bacteria isolated from various foodstuffs. There was good agreement between the results obtained using the present method and those obtained using a conventional staining method. These results suggest that the WST-8 colorimetric assay with selection medium is a useful technique for accurately differentiating Gram-positive and -negative bacteria.

  15. Uncultivated Magnetotactic Cocci from Yuandadu Park in Beijing, China▿

    PubMed Central

    Lin, Wei; Pan, Yongxin

    2009-01-01

    In the present study, we investigated a group of uncultivated magnetotactic cocci, which was magnetically isolated from a freshwater pond in Beijing, China. Light and transmission electron microscopy showed that these cocci ranged from 1.5 to 2.5 μm and contained two to four chains of magnetite magnetosomes, which sometimes were partially disorganized. Overall, the size of the disorganized magnetosomes was significantly smaller than that arranged in chains. All characterized magnetosome crystals were elongated (shape factor = 0.64) and fall into the single-domain size range (30 to 115 nm). Comparative 16S rRNA gene sequence analysis and fluorescence in situ hybridization showed that the enriched bacteria were a virtually homogeneous population and represented a novel lineage in the Alphaproteobacteria. The closest cultivated relative was magnetotactic coccoid strain MC-1 (88% sequence identity). First-order reversal curve diagrams revealed that these cocci had relatively strong magnetic interactions compared to the single-chain magnetotactic bacteria. Low-temperature magnetic measurements showed that the Verwey transition of them was ∼108 K, confirming magnetite magnetosomes, and the delta ratio δFC/δZFC was >2. Based on the structure, phylogenetic position and magnetic properties, the enriched magnetotactic cocci of Alphaproteobacteria are provisionally named as “Candidatus Magnetococcus yuandaducum.” PMID:19376904

  16. Efficacy of telavancin, a lipoglycopeptide antibiotic, in experimental models of Gram-positive infection.

    PubMed

    Hegde, Sharath S; Janc, James W

    2014-12-01

    Telavancin is a parenteral lipoglycopeptide antibiotic with a dual mechanism of action contributing to bactericidal activity against multidrug-resistant Gram-positive pathogens. It has been approved for the treatment of complicated skin and skin structure infections due to susceptible Gram-positive bacteria and hospital-acquired/ventilator-associated bacterial pneumonia due to Staphylococcus aureus when other alternatives are unsuitable. Telavancin has been demonstrated to be efficacious in multiple animal models of soft tissue, cardiac, systemic, lung, bone, brain and device-associated infections involving clinically relevant Gram-positive pathogens, including methicillin-resistant S. aureus, glycopeptide-intermediate S. aureus, heterogeneous vancomycin-intermediate S. aureus and daptomycin non-susceptible methicillin-resistant S. aureus. The AUC0-24h/MIC ratio is the primary pharmacodynamically-linked pharmacokinetic parameter. The preclinical data for telavancin supports further investigative clinical evaluation of its efficacy in additional serious infections caused by susceptible Gram-positive pathogens.

  17. Antibacterial activities of β-glucan (laminaran) against gram-negative and gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Chamidah, A.; Hardoko, Prihanto, A. A.

    2017-05-01

    This study aimed to determine the antibacterial activity of β-Glucan (laminaran) of LAE and LME extracts from brown algae Sargassum crassifolium using HPMS and Ultrasonication against Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (Salmonella typhimurium and Escherichia coli). The highest antibacterial activities of LME extract obtained using the HPMS method against Gram-positive bacteria (B. subtilis and S. aureus) were at 18:10 and 18.80 mm. The ultrasonication method showed a lower inhibition trend than the HPMS method, with MIC and MBC values of 250 mg/ml and 2-8 CFU/ml, respectively, in all Gram-negative and Gram-positive bacteria. The results showed that LME extract at a concentration of 250 mg/mL is bacteriostatic against Gram-positive and -negative bacteria.

  18. Linear alkanesulfonates as carbon and energy sources for gram-positive and gram-negative bacteria.

    PubMed

    Reichenbecher, W; Murrell, J C

    1999-01-01

    Several bacteria from soil and rainwater samples were enriched and isolated with propanesulfonate or butanesulfonate as sole carbon and energy source. Most of the strains isolated utilized nonsubstituted alkanesulfonates with a chain length of C3-C6 and the substituted sulfonates taurine and isethionate as carbon and energy source. A gram-positive isolate, P40, and a gram-negative isolate, P53, were characterized in more detail. Phylogenetic analysis grouped strain P40 within group IV of the genus Rhodococcus and showed a close relationship with Rhodococcus opacus. After phylogenetic and physiological analyses, strain P53 was identified as Comamonas acidovorans. Both bacteria also utilized a wide range of sulfonates as sulfur source. Strain P40, but not strain P53, released sulfite into the medium during dissimilation of sulfonated compounds. Cell-free extracts of strain P53 exhibited high sulfite oxidase activity [2.34 U (mg protein)-1] when assayed with ferricyanide, but not with cytochrome c. Experiments with whole-cell suspensions of both strains showed that the ability to dissimilate 1-propanesulfonate was specifically induced during growth on this substrate and was not present in cells grown on propanol, isethionate or taurine. Whole-cell suspensions of both strains accumulated acetone when oxidizing the non-growth substrate 2-propanesulfonate. Strain P40 cells also accumulated sulfite under these conditions. Stoichiometric measurements with 2-propanesulfonate as substrate in oxygen electrode experiments indicate that the nonsubstituted alkanesulfonates were degraded by a monooxygenase. When strain P53 grew with nonsubstituted alkanesulfonates as carbon and energy source, cells expressed high amounts of yellow pigments, supporting the proposition that an oxygenase containing iron sulfur centres or flavins was involved in their degradation.

  19. The Structure and Function of the Gram-Positive Bacterial RNA Degradosome.

    PubMed

    Cho, Kyu Hong

    2017-01-01

    The RNA degradosome is a highly structured protein complex responsible for bulk RNA decay in bacteria. The main components of the complex, ribonucleases, an RNA helicase, and glycolytic enzymes are well-conserved in bacteria. Some components of the degradosome are essential for growth and the disruption of degradosome formation causes slower growth, indicating that this complex is required for proper cellular function. The study of the Escherichia coli degradosome has been performed extensively for the last several decades and has revealed detailed information on its structure and function. On the contrary, the Gram-positive bacterial degradosome, which contains ribonucleases different from the E. coli one, has been studied only recently. Studies on the Gram-positive degradosome revealed that its major component RNase Y was necessary for the full virulence of medically important Gram-positive bacterial pathogens, suggesting that it could be a target of antimicrobial therapy. This review describes the structures and function of Gram-positive bacterial RNA degradosomes, especially those of a Gram-positive model organism Bacillus subtilis, and two important Gram-positive pathogens, Staphylococcus aureus and Streptococcus pyogenes.

  20. The Structure and Function of the Gram-Positive Bacterial RNA Degradosome

    PubMed Central

    Cho, Kyu Hong

    2017-01-01

    The RNA degradosome is a highly structured protein complex responsible for bulk RNA decay in bacteria. The main components of the complex, ribonucleases, an RNA helicase, and glycolytic enzymes are well-conserved in bacteria. Some components of the degradosome are essential for growth and the disruption of degradosome formation causes slower growth, indicating that this complex is required for proper cellular function. The study of the Escherichia coli degradosome has been performed extensively for the last several decades and has revealed detailed information on its structure and function. On the contrary, the Gram-positive bacterial degradosome, which contains ribonucleases different from the E. coli one, has been studied only recently. Studies on the Gram-positive degradosome revealed that its major component RNase Y was necessary for the full virulence of medically important Gram-positive bacterial pathogens, suggesting that it could be a target of antimicrobial therapy. This review describes the structures and function of Gram-positive bacterial RNA degradosomes, especially those of a Gram-positive model organism Bacillus subtilis, and two important Gram-positive pathogens, Staphylococcus aureus and Streptococcus pyogenes. PMID:28217125

  1. Cytokine profile in severe Gram-positive and Gram-negative abdominal sepsis.

    PubMed

    Surbatovic, Maja; Popovic, Nada; Vojvodic, Danilo; Milosevic, Ivan; Acimovic, Gordana; Stojicic, Milan; Veljovic, Milic; Jevdjic, Jasna; Djordjevic, Dragan; Radakovic, Sonja

    2015-06-16

    Sepsis is a principal cause of death in critical care units worldwide and consumes considerable healthcare resources. The aim of our study was to determine whether the early cytokine profile can discriminate between Gram-positive and Gram-negative bacteraemia (GPB and GNB, respectively) and to assess the prognostic value regarding outcome in critically ill patients with severe abdominal sepsis. The outcome measure was hospital mortality. Blood samples were obtained from 165 adult patients with confirmed severe abdominal sepsis. Levels of the proinflammatory mediators TNF-α, IL-8, IL-12 and IFN-γ and the anti-inflammatory mediators IL-1ra, IL-4, IL-10 and TGF-β1 were determined and correlated with the nature of the bacteria isolated from the blood culture and outcome. The cytokine profile in our study indicated that the TNF-α levels were 2-fold, IL-8 were 3.3-fold, IFN-γ were 13-fold, IL-1ra were 1.05-fold, IL-4 were 1.4-fold and IL-10 were 1.83-fold higher in the GNB group compared with the GPB group. The TNF-α levels were 4.7-fold, IL-8 were 4.6-fold, IL-1ra were 1.5-fold and IL-10 were 3.3-fold higher in the non-survivors compared with the survivors.

  2. Gram-positive pathogenic bacteria induce a common early response in human monocytes

    PubMed Central

    2010-01-01

    Background We infected freshly isolated human peripheral monocytes with live bacteria of three clinically important gram-positive bacterial species, Staphylococcus aureus, Streptococcus pneumoniae and Listeria monocytogenes and studied the ensuing early transcriptional response using expression microarrays. Thus the observed response was unbiased by signals originating from other helper and effector cells of the host and was not limited to induction by solitary bacterial constituents. Results Activation of monocytes was demonstrated by the upregulation of chemokine rather than interleukin genes except for the prominent expression of interleukin 23, marking it as the early lead cytokine. This activation was accompanied by cytoskeleton rearrangement signals and a general anti-oxidative stress and anti-apoptotic reaction. Remarkably, the expression profiles also provide evidence that monocytes participate in the regulation of angiogenesis and endothelial function in response to these pathogens. Conclusion Regardless of the invasion properties and survival mechanisms of the pathogens used, we found that the early response comprised of a consistent and common response. The common response was hallmarked by the upregulation of interleukin 23, a rather unexpected finding regarding Listeria infection, as this cytokine has been linked primarily to the control of extracellular bacterial dissemination. PMID:21044323

  3. Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria.

    PubMed

    Tamboli, Dhawal P; Lee, Dae Sung

    2013-09-15

    The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO₃ solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5-50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis.

  4. Revised mechanism of D-alanine incorporation into cell wall polymers in Gram-positive bacteria.

    PubMed

    Reichmann, Nathalie T; Cassona, Carolina Picarra; Gründling, Angelika

    2013-09-01

    Teichoic acids (TAs) are important for growth, biofilm formation, adhesion and virulence of Gram-positive bacterial pathogens. The chemical structures of the TAs vary between bacteria, though they typically consist of zwitterionic polymers that are anchored to either the peptidoglycan layer as in the case of wall teichoic acid (WTA) or the cell membrane and named lipoteichoic acid (LTA). The polymers are modified with D-alanines and a lack of this decoration leads to increased susceptibility to cationic antimicrobial peptides. Four proteins, DltA-D, are essential for the incorporation of d-alanines into cell wall polymers and it has been established that DltA transfers D-alanines in the cytoplasm of the cell onto the carrier protein DltC. However, two conflicting models have been proposed for the remainder of the mechanism. Using a cellular protein localization and membrane topology analysis, we show here that DltC does not traverse the membrane and that DltD is anchored to the outside of the cell. These data are in agreement with the originally proposed model for D-alanine incorporation through a process that has been proposed to proceed via a D-alanine undecaprenyl phosphate membrane intermediate. Furthermore, we found that WTA isolated from a Staphylococcus aureus strain lacking LTA contains only a small amount of D-alanine, indicating that LTA has a role, either direct or indirect, in the efficient D-alanine incorporation into WTA in living cells.

  5. Use of PNA FISH for blood cultures growing Gram-positive cocci in chains without a concomitant antibiotic stewardship intervention does not improve time to appropriate antibiotic therapy.

    PubMed

    Cosgrove, Sara E; Li, David X; Tamma, Pranita D; Avdic, Edina; Hadhazy, Eric; Wakefield, Teresa; Gherna, Michael; Carroll, Karen C

    2016-09-01

    Peptide nucleic acid fluorescence in situ hybridization (PNA FISH) is a rapid diagnostic assay that can identify certain organisms growing in blood cultures 30-90 min from the time of positive Gram-stain. Existing studies have demonstrated a clinical utility with this assay when antibiotic stewardship programs assist clinicians with interpreting the results. However, the benefit of these rapid assays in the absence of concomitant antibiotic stewardship involvement is unclear. In this randomized study of 220 patients with enterococcal or streptococcal bacteremia, we found that PNA FISH, in the absence of concomitant input from an antibiotic stewardship program, had no impact on time to effective or optimal therapy, length of hospital stay, or in-hospital mortality. Our results suggest that in the absence of guidance from an antibiotic stewardship program, the clinical benefits of rapid diagnostic microbiological tools may be reduced.

  6. [The antibacterial activity of cinnamon oil on the selected gram-positive and gram-negative bacteria].

    PubMed

    Urbaniak, Anna; Głowacka, Anna; Kowalczyk, Edward; Lysakowska, Monika; Sienkiewicz, Monika

    2014-01-01

    The aim of our study was to determine the antibacterial activity of cinnamon bark oil against Gram-positive and Gram-negative isolates belonging to Staphylococcus, Enterococcus, Enterobacter and Acinetobacter genera come from different clinical specimens. The microdilution method was used to determine the minimum inhibitory concentration--MIC for cinnamon bark oil. Susceptibility testing to antibiotics was carried out using disc-diffusion method. Our investigations showed that the tested cinnamon bark oil was inhibiting activity against all isolates. The MIC for Gram-positive bacteria were between 01.25 and 1.5 μl/ml and for Gram-negative between 1.0 and 1.75 μl/ml. The tested bacteria come from Staphylococcus, Enterococcus, Enterobacter and Acinetobacter genera were susceptible to essential oil obtained from Cinnamomum zeylanicum Ness in low concentrations, despite the fact that the bacteria characterized the high resistance to recommended antibiotics. No correlation was found between the antibiotic resistance of the bacterial strains and their sensitivity to essential oil. The cinnamon bark oil due to the strong activity can be used as alternative antibacterial agents in cosmetics, toiletries and disinfectants applied in hospital environment.

  7. Bio-fabricated silver nanoparticles preferentially targets Gram positive depending on cell surface charge.

    PubMed

    Mandal, Debasis; Kumar Dash, Sandeep; Das, Balaram; Chattopadhyay, Sourav; Ghosh, Totan; Das, Debasis; Roy, Somenath

    2016-10-01

    Recently bio-inspired experimental processes for synthesis of nanoparticles are receiving significant attention in nanobiotechnology. Silver nanoparticles (Ag NPs) have been used very frequently in recent times to the wounds, burns and bacterial infections caused by drug-resistant microorganisms. Though, the antibacterial effects of Ag NPs on some multi drug-resistant bacteria specially against Gram positive bacteria has been established, but further investigation is needed to elicit its effectiveness against Gram negatives and to identify the probable mechanism of action. Thus, the present study was conducted to synthesize Ag NPs using Andrographis paniculata leaf extract and to investigate its antibacterial efficacy. After synthesis process the biosynthesized nanoparticles were purified and characterized with the help of various physical measurement techniques which raveled their purity, stability and small size range. The antimicrobial activity of Ag NPs was determined against both Gram-positive Enterococcus faecalis and Gram-negative Proteus vulgaris. Results showed comparatively higher antibacterial efficacy of Ag NPs against Gram positive Enterococcus faecalis strains. It was found that greater difference in zeta potential values between Gram positive bacteria and Ag NPs triggers better internalization of the particles. Thus the cell surface charge played vital role in cell killing which was confirmed by surface zeta potential study. Finally it may be concluded that green synthesized Ag NPs using Andrographis paniculata leaf extract can be very useful against both multi drug resistant Gram-positive and Gram-negative bacteria.

  8. Human cytokine responses induced by Gram-positive cell walls of normal intestinal microbiota

    PubMed Central

    Chen, T; Isomäki, P; Rimpiläinen, M; Toivanen, P

    1999-01-01

    The normal microbiota plays an important role in the health of the host, but little is known of how the human immune system recognizes and responds to Gram-positive indigenous bacteria. We have investigated cytokine responses of peripheral blood mononuclear cells (PBMC) to Gram-positive cell walls (CW) derived from four common intestinal indigenous bacteria, Eubacterium aerofaciens (Eu.a.), Eubacterium limosum(Eu.l.), Lactobacillus casei(L.c.), and Lactobacillus fermentum (L.f.). Our results indicate that Gram-positive CW of the normal intestinal microbiota can induce cytokine responses of the human PBMC. The profile, level and kinetics of these responses are similar to those induced by lipopolysaccharide (LPS) or CW derived from a pathogen, Streptococcus pyogenes (S.p.). Bacterial CW are capable of inducing production of a proinflammatory cytokine, tumour necrosis factor-alpha (TNF-α), and an anti-inflammatory cytokine, IL-10, but not that of IL-4 or interferon-gamma (IFN-γ). Monocytes are the main cell population in PBMC to produce TNF-α and IL-10. Induction of cytokine secretion is serum-dependent; both CD14-dependent and -independent pathways are involved. These findings suggest that the human cytokine responses induced by Gram-positive CW of the normal intestinal microbiota are similar to those induced by LPS or Gram-positive CW of the pathogens. PMID:10540188

  9. [Prevalence and treatment of Gram-positive infections in internal medicine departments of Spanish hospitals: IGP Study].

    PubMed

    González-Romo, F; Rubio, M; Betriu, C; Picazo, J J

    2003-12-01

    This study aimed to identify therapeutic approaches and the tendencies of Gram-positive infections in Spanish hospitals in terms of prevalence, origin, location and etiology, as well as the characteristics of patients with these infections, their underlying illnesses, the severity and predisposing factors. We used statistical analysis to compare the results of two multicenter prevalence studies, the first from 1994-1995, and the second in 1998. We found a statistically significant decrease in the percentage of infected patients (45.8% vs. 32.8%; p <0.001), but an increase in infections by Gram-positive microorganisms (14.4% vs. 20.6%; p <0.001), which was reflected in the increased use of glycopeptides (17.1% vs. 31.2%; p = 0.002). The use of quinolones also increased. The most common underlying illnesses were heart disease and diabetes mellitus, and there was a reduction in the number of patients infected by HIV and in users of parenteral medication. The decrease in outpatient infections indicated that nosocomial infection was more frequent in the second study, in which the number of predisposing factors increased (52.3% vs. 79.2%; p <0.001), the most common of which were peripheral line, immobilization and a bladder catheter. Bacteremia was the most frequent infection, and there was a reduction in lower respiratory tract infections and an increase in skin and soft tissue infections. Staphylococcus aureus was the most frequently found microorganism and showed a significant increase in incidence (27.2% vs. 47.9%; p <0.001), whereas pneumococcus showed a decrease (15.0% vs. 5.2%; p = 0.012). It was concluded that despite the decrease in the percentage of infected patients and severely ill patients, there is an increase in Gram-positive infections, especially bacteremia, and in the use of more aggressive treatments. This may reflect the increase in resistant isolates.

  10. Surface multiheme c-type cytochromes from Thermincola potens and implications for respiratory metal reduction by Gram-positive bacteria.

    PubMed

    Carlson, Hans K; Iavarone, Anthony T; Gorur, Amita; Yeo, Boon Siang; Tran, Rosalie; Melnyk, Ryan A; Mathies, Richard A; Auer, Manfred; Coates, John D

    2012-01-31

    Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they may be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or anthraquinone-2,6-disulfonate (AQDS), an analog of the redox active components of humic substances. The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin-shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS, and that several MHCs are localized to the cell wall or cell surface. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants, suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results provide unique direct evidence for cell wall-associated cytochromes and support MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.

  11. Surface multiheme c-type cytochromes from Thermincola potens and implications for respiratory metal reduction by Gram-positive bacteria

    PubMed Central

    Carlson, Hans K.; Iavarone, Anthony T.; Gorur, Amita; Yeo, Boon Siang; Tran, Rosalie; Melnyk, Ryan A.; Mathies, Richard A.; Auer, Manfred; Coates, John D.

    2012-01-01

    Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they may be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or anthraquinone-2,6-disulfonate (AQDS), an analog of the redox active components of humic substances. The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin-shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS, and that several MHCs are localized to the cell wall or cell surface. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants, suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results provide unique direct evidence for cell wall-associated cytochromes and support MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium. PMID:22307634

  12. Thusin, a Novel Two-Component Lantibiotic with Potent Antimicrobial Activity against Several Gram-Positive Pathogens

    PubMed Central

    Xin, Bingyue; Zheng, Jinshui; Liu, Hualin; Li, Junhua; Ruan, Lifang; Peng, Donghai; Sajid, Muhammad; Sun, Ming

    2016-01-01

    Due to the rapidly increasing prevalence of multidrug-resistant bacterial strains, the need for new antimicrobial drugs to treat infections has become urgent. Bacteriocins, which are antimicrobial peptides of bacterial origin, are considered potential alternatives to conventional antibiotics and have attracted widespread attention in recent years. Among these bacteriocins, lantibiotics, especially two-component lantibiotics, exhibit potent antimicrobial activity against some clinically relevant Gram-positive pathogens and have potential applications in the pharmaceutical industry. In this study, we characterized a novel two-component lantibiotic termed thusin that consists of Thsα, Thsβ, and Thsβ' (mutation of Thsβ, A14G) and that was isolated from a B. thuringiensis strain BGSC 4BT1. Thsα and Thsβ (or Thsβ') exhibit optimal antimicrobial activity at a 1:1 ratio and act sequentially to affect target cells, and they are all highly thermostable (100°C for 30 min) and pH tolerant (pH 2.0 to 9.0). Thusin shows remarkable efficacy against all tested Gram-positive bacteria and greater activities than two known lantibiotics thuricin 4A-4 and ticin A4, and one antibiotic vancomycin against various bacterial pathogens (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus (MRSA), Staphylococcus sciuri, Enterococcus faecalis, and Streptococcus pneumoniae). Moreover, thusin is also able to inhibit the outgrowth of B. cereus spores. The potent antimicrobial activity of thusin against some Gram-positive pathogens indicates that it has potential for the development of new drugs. PMID:27486447

  13. Mechanism of action of recombinant acc-royalisin from royal jelly of Asian honeybee against gram-positive bacteria.

    PubMed

    Shen, Lirong; Liu, Dandan; Li, Meilu; Jin, Feng; Din, Meihui; Parnell, Laurence D; Lai, Chao-Qiang

    2012-01-01

    The antibacterial activity of royalisin, an antimicrobial peptide from the royal jelly produced by honeybees, has been addressed extensively. However, its mechanism of action remains unclear. In this study, a recombinant royalisin, RAcc-royalisin from the royal jelly of Asian honeybee Apis cerana cerana, was expressed by fusing with glutathione S-transferase (GST) in Escherichia coli BL21, isolated and purified. The agar dilution assays with inhibition zone showed that RAcc-royalisin, similar to nisin, inhibits the growth of Gram-positive bacteria. The antibacterial activity of RAcc-royalisin was associated with its concentration, and was weakened by heat treatment ranging from 55°C to 85°C for 15 min. Both RAcc-royalisin and nisin exhibited the minimum inhibitory concentrations (MIC) of 62.5 µg/ml, 125 µg/ml, and 250 µg/ml against Gram-positive bacterial strains, Bacillus subtilis and Micrococcus flavus and Staphyloccocus aureus in the microplate assay, respectively. However, RAcc-royalisin did not show antimicrobial activity against tested Gram-negative bacterial and fungal strains. The antibacterial activity of RAcc-royalisin agrees well with the decrease in bacterial cell hydrophobicity, the leakage of 260-nm absorbing materials, and the observation by transmission electron microscopy, all indicating that RAcc-royalisin induced the disruption and dysfunction of cell walls and membranes. This is the first report detailing the antibacterial mechanism of royalisin against Gram-positive bacteria, and provides insight into the application of recombinant royalisin in food and pharmaceutical industries as an antimicrobial agent.

  14. Surface multiheme c-type cytochromes from Thermincola potens: Implications for dissimilatory metal reduction by Gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Carlson, H. K.; Iavarone, A. T.; Gorur, A.; Yeo, B. S.; Tran, R.; Melnyk, R. A.; Mathies, R. A.; Auer, M.; Coates, J. D.

    2011-12-01

    Almost nothing is known about the mechanisms of dissimilatory metal reduction by Gram-positive bacteria, although they have been shown to be the dominant species in some environments. Thermincola potens strain JR was isolated from the anode of a microbial fuel cell inoculated with anaerobic digester sludge and operated at 55 °C. Preliminary characterization revealed that T. potens coupled acetate oxidation to the reduction of hydrous ferric oxides (HFO) or the humic substances analog, anthraquinone-2,6-disulfonate (AQDS). The genome of T. potens was recently sequenced, and the abundance of multiheme c-type cytochromes (MHCs) is unusual for a Gram-positive bacterium. We present evidence from trypsin shaving LC-MS/MS experiments and surface-enhanced Raman spectroscopy (SERS) that indicates the expression of a number of MHCs during T. potens growth on either HFO or AQDS and that several MHCs are localized to the cell wall or cell surface of T. potens. Furthermore, one of the MHCs can be extracted from cells with low pH or denaturants suggesting a loose association with the cell wall or cell surface. Electron microscopy does not reveal an S-layer, and the precipitation of silver metal on the cell surface is inhibited by cyanide, supporting the involvement of surface-localized redox-active heme proteins in dissimilatory metal reduction. These results are the first direct evidence for cell-wall associated cytochromes and MHC involvement in conducting electrons across the cell envelope of a Gram-positive bacterium.

  15. Mechanism of Action of Recombinant Acc-Royalisin from Royal Jelly of Asian Honeybee against Gram-Positive Bacteria

    PubMed Central

    Shen, Lirong; Liu, Dandan; Li, Meilu; Jin, Feng; Din, Meihui; Parnell, Laurence D.; Lai, Chao-Qiang

    2012-01-01

    The antibacterial activity of royalisin, an antimicrobial peptide from the royal jelly produced by honeybees, has been addressed extensively. However, its mechanism of action remains unclear. In this study, a recombinant royalisin, RAcc-royalisin from the royal jelly of Asian honeybee Apis cerana cerana, was expressed by fusing with glutathione S-transferase (GST) in Escherichia coli BL21, isolated and purified. The agar dilution assays with inhibition zone showed that RAcc-royalisin, similar to nisin, inhibits the growth of Gram-positive bacteria. The antibacterial activity of RAcc-royalisin was associated with its concentration, and was weakened by heat treatment ranging from 55°C to 85°C for 15 min. Both RAcc-royalisin and nisin exhibited the minimum inhibitory concentrations (MIC) of 62.5 µg/ml, 125 µg/ml, and 250 µg/ml against Gram-positive bacterial strains, Bacillus subtilis and Micrococcus flavus and Staphyloccocus aureus in the microplate assay, respectively. However, RAcc-royalisin did not show antimicrobial activity against tested Gram-negative bacterial and fungal strains. The antibacterial activity of RAcc-royalisin agrees well with the decrease in bacterial cell hydrophobicity, the leakage of 260-nm absorbing materials, and the observation by transmission electron microscopy, all indicating that RAcc-royalisin induced the disruption and dysfunction of cell walls and membranes. This is the first report detailing the antibacterial mechanism of royalisin against Gram-positive bacteria, and provides insight into the application of recombinant royalisin in food and pharmaceutical industries as an antimicrobial agent. PMID:23056609

  16. Bactericidal Activity and Mechanism of Photoirradiated Polyphenols against Gram-Positive and -Negative Bacteria.

    PubMed

    Nakamura, Keisuke; Ishiyama, Kirika; Sheng, Hong; Ikai, Hiroyo; Kanno, Taro; Niwano, Yoshimi

    2015-09-09

    The bactericidal effect of various types of photoirradiated polyphenols against Gram-positive and -negative bacteria was evaluated in relation to the mode of action. Gram-positive bacteria (Enterococcus faecalis, Staphylococcus aureus, and Streptococcus mutans) and Gram-negative bacteria (Aggregatibacter actinomycetemcomitans, Escherichia coli, and Pseudomonas aeruginosa) suspended in a 1 mg/mL polyphenol aqueous solution (caffeic acid, gallic acid, chlorogenic acid, epigallocatechin, epigallocatechin gallate, and proanthocyanidin) were exposed to LED light (wavelength, 400 nm; irradiance, 260 mW/cm(2)) for 5 or 10 min. Caffeic acid and chlorogenic acid exerted the highest bactericidal activity followed by gallic acid and proanthocyanidin against both Gram-positive and -negative bacteria. It was also demonstrated that the disinfection treatment induced oxidative damage of bacterial DNA, which suggests that polyphenols are incorporated into bacterial cells. The present study suggests that blue light irradiation of polyphenols could be a novel disinfection treatment.

  17. Labeling and Selective Inactivation of Gram-Positive Bacteria Employing Bimodal Photoprobes with Dual Readouts.

    PubMed

    Galstyan, Anzhela; Block, Desiree; Niemann, Silke; Grüner, Malte C; Abbruzzetti, Stefania; Oneto, Michele; Daniliuc, Constantin G; Hermann, Sven; Viappiani, Cristiano; Schäfers, Michael; Löffler, Bettina; Strassert, Cristian A; Faust, Andreas

    2016-04-04

    Carbohydrate-conjugated silicon(IV) phthalocyanines with bimodal photoactivity were developed as probes with both fluorescent labeling and photosensitizing capabilities, and the concomitant fluorescent labeling and photoinduced inactivation of Gram-positive and Gram-negative models was explored. The maltohexaose-conjugated photoprobe provides a dual readout to distinguish between both groups of pathogens, as only the Gram-positive species was inactivated, even though both appeared labeled with near-infrared luminescence. Antibiotic resistance did not hinder the phototoxic effect, as even the methicillin-resistant pathogen Staphylococcus aureus (MRSA) was completely photoinactivated. Time-resolved confocal fluorescence microscopy analysis suggests that the photoprobe sticks onto the outer rim of the microorganisms, explaining the resistance of Gram-negative species on the basis of their membrane constitution. The mannose-conjugated photoprobe yields a different readout because it is able to label and to inactivate only the Gram-positive strain.

  18. Class D β-lactamases do exist in Gram-positive bacteria

    SciTech Connect

    Toth, Marta; Antunes, Nuno Tiago; Stewart, Nichole K.; Frase, Hilary; Bhattacharya, Monolekha; Smith, Clyde A.; Vakulenko, Sergei B.

    2015-11-09

    Production of β-lactamases of one of four molecular classes (A, B, C and D) is the major mechanism of bacterial resistance to β-lactams, the largest class of antibiotics, which have saved countless lives since their inception 70 years ago. Although several hundred efficient class D enzymes have been identified in Gram-negative pathogens over the last four decades, none have been reported in Gram-positive bacteria. Here we demonstrate that efficient class D β-lactamases capable of hydrolyzing a wide array of β-lactam substrates are widely disseminated in various species of environmental Gram-positive organisms. Class D enzymes of Gram-positive bacteria have a distinct structural architecture and employ a unique substrate-binding mode that is quite different from that of all currently known class A, C and D β-lactamases. In conclusion, these enzymes thus constitute a previously unknown reservoir of novel antibiotic-resistance enzymes.

  19. Nucleotide sequence alignment of hdcA from Gram-positive bacteria.

    PubMed

    Diaz, Maria; Ladero, Victor; Redruello, Begoña; Sanchez-Llana, Esther; Del Rio, Beatriz; Fernandez, Maria; Martin, Maria Cruz; Alvarez, Miguel A

    2016-03-01

    The decarboxylation of histidine -carried out mainly by some gram-positive bacteria- yields the toxic dietary biogenic amine histamine (Ladero et al. 2010 〈10.2174/157340110791233256〉 [1], Linares et al. 2016 〈http://dx.doi.org/10.1016/j.foodchem.2015.11.013〉〉 [2]). The reaction is catalyzed by a pyruvoyl-dependent histidine decarboxylase (Linares et al. 2011 〈10.1080/10408398.2011.582813〉 [3]), which is encoded by the gene hdcA. In order to locate conserved regions in the hdcA gene of Gram-positive bacteria, this article provides a nucleotide sequence alignment of all the hdcA sequences from Gram-positive bacteria present in databases. For further utility and discussion, see 〈http://dx.doi.org/ 10.1016/j.foodcont.2015.11.035〉〉 [4].

  20. Nucleotide sequence alignment of hdcA from Gram-positive bacteria

    PubMed Central

    Diaz, Maria; Ladero, Victor; Redruello, Begoña; Sanchez-Llana, Esther; del Rio, Beatriz; Fernandez, Maria; Martin, Maria Cruz; Alvarez, Miguel A.

    2016-01-01

    The decarboxylation of histidine -carried out mainly by some gram-positive bacteria- yields the toxic dietary biogenic amine histamine (Ladero et al. 2010 〈10.2174/157340110791233256〉 [1], Linares et al. 2016 〈http://dx.doi.org/10.1016/j.foodchem.2015.11.013〉〉 [2]). The reaction is catalyzed by a pyruvoyl-dependent histidine decarboxylase (Linares et al. 2011 〈10.1080/10408398.2011.582813〉 [3]), which is encoded by the gene hdcA. In order to locate conserved regions in the hdcA gene of Gram-positive bacteria, this article provides a nucleotide sequence alignment of all the hdcA sequences from Gram-positive bacteria present in databases. For further utility and discussion, see 〈http://dx.doi.org/ 10.1016/j.foodcont.2015.11.035〉〉 [4]. PMID:26958625

  1. Class D β-lactamases do exist in Gram-positive bacteria

    PubMed Central

    Toth, Marta; Antunes, Nuno Tiago; Stewart, Nichole K.; Frase, Hilary; Bhattacharya, Monolekha; Smith, Clyde; Vakulenko, Sergei

    2015-01-01

    Production of β-lactamases of the four molecular classes (A, B, C, and D) is the major mechanism of bacterial resistance to β-lactams, the largest class of antibiotics that have saved countless lives since their inception 70 years ago. Although several hundred efficient class D enzymes have been identified in Gram-negative pathogens over the last four decades, they have not been reported in Gram-positive bacteria. Here we demonstrate that efficient class D β-lactamases capable of hydrolyzing a wide array of β-lactam substrates are widely disseminated in various species of environmental Gram-positive organisms. Class D enzymes of Gram-positive bacteria have a distinct structural architecture and employ a unique substrate binding mode quite different from that of all currently known class A, C, and D β-lactamases. They constitute a novel reservoir of antibiotic resistance enzymes. PMID:26551395

  2. Rose Bengal-decorated silica nanoparticles as photosensitizers for inactivation of gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Guo, Yanyan; Rogelj, Snezna; Zhang, Peng

    2010-02-01

    A new type of photosensitizer, made from Rose Bengal (RB)-decorated silica (SiO2-NH2-RB) nanoparticles, was developed to inactivate gram-positive bacteria, including Methicillin-resistant Staphylococcus aureus (MRSA), with high efficiency through photodynamic action. The nanoparticles were characterized microscopically and spectroscopically to confirm their structures. The characterization of singlet oxygen generated by RB, both free and immobilized on a nanoparticle surface, was performed in the presence of anthracene-9,10-dipropionic acid. The capability of SiO2-NH2-RB nanoparticles to inactivate bacteria was tested in vitro on both gram-positive and gram-negative bacteria. The results showed that RB-decorated silica nanoparticles can inactivate MRSA and Staphylococcus epidermidis (both gram-positive) very effectively (up to eight-orders-of-magnitude reduction). Photosensitizers of such design should have good potential as antibacterial agents through a photodynamic mechanism.

  3. Interaction of cationic peptides with lipoteichoic acid and gram-positive bacteria.

    PubMed

    Scott, M G; Gold, M R; Hancock, R E

    1999-12-01

    Compounds with antiendotoxin properties have been extensively studied for their potential as therapeutic agents for sepsis attributable to gram-negative bacteria. However, with the increasing incidence of gram-positive sepsis, there is interest in identifying compounds with a broad spectrum of action against both gram-positive and gram-negative bacteria. A series of synthetic alpha-helical cationic peptides related to bee melittin and silk moth cecropin have previously been shown to bind lipopolysaccharide (LPS) with high affinity, inhibit LPS-induced tumor necrosis factor alpha (TNF-alpha) production in vitro and in vivo, and kill gram-negative bacteria. In this study, we analyzed whether these peptides were active against gram-positive bacteria; whether they could bind to lipoteichoic acid (LTA), the major proinflammatory structure on gram-positive bacteria; and whether they could block the ability of LTA to promote the release of cytokines by the RAW 264.7 murine macrophage cell line. We found that the cationic peptides demonstrated moderate growth-inhibitory activity toward gram-positive bacteria. In addition, the peptides bound LTA with high affinity. This correlated with the ability of the peptides to block LTA-induced production of TNF and interleukin-6 by RAW 264.7 cells but did not correlate with their ability to kill the bacteria. The peptides also effectively inhibited LTA-induced TNF production in a whole human blood assay. The peptides were also able to partly block the ability of heat-killed Staphylococcus aureus, as well as soluble products of live S. aureus, to stimulate cytokine production by macrophages. Our results indicate that these cationic peptides may be useful to prevent sepsis and inflammation caused by both gram-negative and gram-positive bacteria.

  4. Experience With Rapid Microarray-Based Diagnostic Technology and Antimicrobial Stewardship for Patients With Gram-Positive Bacteremia.

    PubMed

    Neuner, Elizabeth A; Pallotta, Andrea M; Lam, Simon W; Stowe, David; Gordon, Steven M; Procop, Gary W; Richter, Sandra S

    2016-11-01

    OBJECTIVE To describe the impact of rapid diagnostic microarray technology and antimicrobial stewardship for patients with Gram-positive blood cultures. DESIGN Retrospective pre-intervention/post-intervention study. SETTING A 1,200-bed academic medical center. PATIENTS Inpatients with blood cultures positive for Staphylococcus aureus, Enterococcus faecalis, E. faecium, Streptococcus pneumoniae, S. pyogenes, S. agalactiae, S. anginosus, Streptococcus spp., and Listeria monocytogenes during the 6 months before and after implementation of Verigene Gram-positive blood culture microarray (BC-GP) with an antimicrobial stewardship intervention. METHODS Before the intervention, no rapid diagnostic technology was used or antimicrobial stewardship intervention was undertaken, except for the use of peptide nucleic acid fluorescent in situ hybridization and MRSA agar to identify staphylococcal isolates. After the intervention, all Gram-positive blood cultures underwent BC-GP microarray and the antimicrobial stewardship intervention consisting of real-time notification and pharmacist review. RESULTS In total, 513 patients with bacteremia were included in this study: 280 patients with S. aureus, 150 patients with enterococci, 82 patients with stretococci, and 1 patient with L. monocytogenes. The number of antimicrobial switches was similar in the pre-BC-GP (52%; 155 of 300) and post-BC-GP (50%; 107 of 213) periods. The time to antimicrobial switch was significantly shorter in the post-BC-GP group than in the pre-BC-GP group: 48±41 hours versus 75±46 hours, respectively (P<.001). The most common antimicrobial switch was de-escalation and time to de-escalation, was significantly shorter in the post-BC-GP group than in the pre-BC-GP group: 53±41 hours versus 82±48 hours, respectively (P<.001). There was no difference in mortality or hospital length of stay as a result of the intervention. CONCLUSIONS The combination of a rapid microarray diagnostic test with an antimicrobial

  5. Predictive Factors of Spontaneous Bacterial Peritonitis Caused by Gram-Positive Bacteria in Patients With Cirrhosis.

    PubMed

    Kim, Jung Ho; Jeon, Yong Duk; Jung, In Young; Ahn, Mi Young; Ahn, Hea Won; Ahn, Jin Young; Ku, Nam Su; Han, Sang Hoon; Choi, Jun Yong; Ahn, Sang Hoon; Song, Young Goo; Han, Kwang Hyub; Kim, June Myung

    2016-04-01

    Spontaneous bacterial peritonitis (SBP) in patients with cirrhosis is typically caused by gram-negative bacteria. However, the number of SBP cases due to gram-positive bacteria is steadily increasing. To date, little is known about the predictive factors involved in SBP infections.We performed a retrospective cohort study of patients (>18 years) with SBP due to gram-positive and -negative bacteria who were enrolled from January 2006 to December 2013 at Severance Hospital in Seoul, Korea where the incidences of hepatitis B virus associated chronic liver disease, cirrhosis, and hepatocellular carcinoma are high. Only the 1st SBP episode for each patient within the study period was included in our analysis.We identified 77 patients with cirrhosis and SBP. Of these, 27 patients (35%) had gram-positive bacterial infections and 50 patients (65%) had gram-negative bacterial infections. Our univariate analysis revealed that an early stage of cirrhosis (P = 0.004), lower creatinine level (P = 0.011), lower Sequential Organ Failure Assessment (SOFA) score (P = 0.001), lower Model for End-Stage Liver Disease score (P = 0.005), and use of systemic antibiotics within 30 days before SBP diagnosis (P = 0.03) were significantly associated with gram-positive bacterial infections. Our multivariate analysis indicated that the use of systemic antibiotics within 30 days before SBP diagnosis (odds ratio, 3.94; 95% CI, 1.11-13.96; P = 0.033) and a lower SOFA score (odds ratio, 0.56; 95% CI, 0.37-0.86; P = 0.007) were independent predictive factors of SBP caused by gram-positive bacterial infections in patients with cirrhosis. However, we did not observe a statistically significant difference in the 28-day mortality between the gram-positive and -negative bacterial infection groups (40.7% vs 46.0%, respectively; P = 0.407).In this study, the incidence rate of SBP caused by gram-positive bacteria in patients with cirrhosis was similar to the rates reported

  6. The use of lysozyme modified with fluorescein for the detection of Gram-positive bacteria.

    PubMed

    Arabski, Michał; Konieczna, Iwona; Tusińska, Ewa; Wąsik, Sławomir; Relich, Inga; Zając, Krzysztof; Kamiński, Zbigniew J; Kaca, Wiesław

    2015-01-01

    Lysozyme (1,4-β-N-acetylmuramidase) is commonly applied in the food, medical, and pharmaceutical industries. In this study, we tested a novel application of fluorescein-modified lysozyme (using carboxyfluorescein with a triazine-based coupling reagent) as a new tool for the detection of Gram-positive soil bacteria. The results, obtained by cultivation methods, fluorescence analysis, and laser interferometry, showed that, after optimization, fluorescein-modified lysozyme could be used to evaluate the prevalence of Gram-positive bacteria essential in bioremediation of soils with low pH, such as those degraded by sulfur.

  7. Predicting gram-positive bacterial protein subcellular localization based on localization motifs.

    PubMed

    Hu, Yinxia; Li, Tonghua; Sun, Jiangming; Tang, Shengnan; Xiong, Wenwei; Li, Dapeng; Chen, Guanyan; Cong, Peisheng

    2012-09-07

    The subcellular localization of proteins is closely related to their functions. In this work, we propose a novel approach based on localization motifs to improve the accuracy of predicting subcellular localization of Gram-positive bacterial proteins. Our approach performed well on a five-fold cross validation with an overall success rate of 89.5%. Besides, the overall success rate of an independent testing dataset was 97.7%. Moreover, our approach was tested using a new experimentally-determined set of Gram-positive bacteria proteins and achieved an overall success rate of 96.3%.

  8. Fresh layers of RNA-mediated regulation in Gram-positive bacteria.

    PubMed

    Bouloc, Philippe; Repoila, Francis

    2016-04-01

    Bacterial regulatory RNAs have been defined as diverse classes of cis and trans elements that may intervene at each step of gene expression, from RNA and protein synthesis to degradation. Here, we report on a few examples from Gram-positive bacteria that extend the definition of regulatory RNAs to include 5' and 3' UTRs that also act as cis and trans regulators. New examples unveil the existence of cis and trans acting regulatory RNAs on a single molecule. Also, we highlight data showing that a key RNA chaperone in Enterobacteriaceae, Hfq, does not fulfill the same role in Gram-positive Firmicutes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Quorum sensing in gram-positive bacteria: assay protocols for staphylococcal agr and enterococcal fsr systems.

    PubMed

    Shojima, Akane; Nakayama, Jiro

    2014-01-01

    A thiolactone/lactone peptide-mediated quorum sensing (QS) system is commonly employed in gram-positive bacteria to control the expression of a variety of phenotypes, including the production of virulence factors and biofilm formation. Here, we describe assay protocols for the well-studied QS systems (agr and fsr) of two representative gram-positive pathogens, Staphylococcus aureus and Enterococcus faecalis. These convenient assay systems are useful for the screening of QS inhibitors as well as for basic research to address the mechanism of these QS systems.

  10. Ceftaroline Plus Ampicillin Against Gram-Positive Organisms: Results from E-Test Synergy Assays.

    PubMed

    D'Arezzo, Silvia; Mazzarelli, Antonio; Venditti, Carolina; Nisii, Carla; Petrosillo, Nicola; De Giuli, Chiara; Vulcano, Antonella; Paglia, Maria Grazia; Bordi, Eugenio; Di Caro, Antonino; Taglietti, Fabrizio

    2017-06-01

    In an era of increasing drug resistance and limited numbers of antimicrobials in the drug production pipeline, healthcare-associated infections represent a growing public health threat. When therapeutic options are limited, clinicians often resort to using antimicrobial combinations that produce a synergistic effect on the target pathogen. Novel antibiotics are therefore welcome in the daily practice of medicine. For example, ceftaroline is a broad-spectrum cephalosporin active against a variety of bacteria, including methicillin-resistant Staphylococcus aureus, but with limited activity against enterococci, particularly Enterococcus faecium. In this study, we tested the efficacy of ceftaroline against clinical isolates of gram-positive bacteria (S. aureus, Enterococcus faecalis, and E. faecium) by the broth microdilution and E-test assays, and then evaluated the synergistic effect of ceftaroline and ampicillin using the E-test method. The time-kill assay was used to confirm the data on selected strains. This drug combination has been recently shown to be effective against E. faecalis and could offer the advantage of cost-effectiveness (compared to other synergistic associations) as well as good tolerability. The E-test was chosen because of its relative simplicity of use that makes it suitable for routine clinical laboratories as a quick tool to guide clinicians when confronted with difficult-to-treat infections that may require an empirical approach. Our results indicate the presence of a synergistic effect of ceftaroline and ampicillin on most of the strains used, especially E. faecium and E. faecalis. The fact that two of those Enterococcus strains were vancomycin resistant suggests that the possible use of this combination for combating the spread of vancomycin-resistant enterococci should be explored.

  11. Comparison of the Bruker MALDI-TOF mass spectrometry system and conventional phenotypic methods for identification of Gram-positive rods.

    PubMed

    Barberis, Claudia; Almuzara, Marisa; Join-Lambert, Olivier; Ramírez, María Soledad; Famiglietti, Angela; Vay, Carlos

    2014-01-01

    In recent years, MALDI-TOF Mass Spectrometry (MS) method has emerged as a promising and a reliable tool for bacteria identification. In this study we compared Bruker MALDI-TOF MS and conventional phenotypic methods to identify a collection of 333 Gram-positive clinical isolates comprising 22 genera and 60 species. 16S rRNA sequencing was the reference molecular technique, and rpoB gene sequecing was used as a secondary gene target when 16Sr RNA did not allow species identification of Corynebacterium spp. We also investigate if score cut-offs values of ≥ 1,5 and ≥ 1,7 were accurate for genus and species-level identification using the Bruker system. Identification at species level was obtained for 92,49% of Gram-positive rods by MALDI-TOF MS compared to 85,89% by phenotypic method. Our data validates the score ≥ 1,5 for genus level and ≥ 1,7 for species-level identification in a large and diverse collection of Gram-positive rods. The present study has proved the accuracy of MALDI-TOF MS as an identification method in Gram-positive rods compared to currently used methods in routine laboratories.

  12. An extreme-halophile archaebacterium possesses the interlock type of prephenate dehydratase characteristic of the Gram-positive eubacteria

    NASA Technical Reports Server (NTRS)

    Jensen, R. A.; d'Amato, T. A.; Hochstein, L. I.

    1988-01-01

    The focal point of phenylalanine biosynthesis is a dehydratase reaction which in different organisms may be prephenate dehydratase, arogenate dehydratase, or cyclohexadienyl dehydratase. Gram-positive, Gram-negative, and cyanobacterial divisions of the eubacterial kingdom exhibit different dehydratase patterns. A new extreme-halophile isolate, which grows on defined medium and is tentatively designated as Halobacterium vallismortis CH-1, possesses the interlock type of prephenate dehydratase present in Gram-positive bacteria. In addition to the conventional sensitivity to feedback inhibition by L-phenylalanine, the phenomenon of metabolic interlock was exemplified by the sensitivity of prephenate dehydratase to allosteric effects produced by extra-pathway (remote) effectors. Thus, L-tryptophan inhibited activity while L-tyrosine, L-methionine, L-leucine and L-isoleucine activated the enzyme. L-Isoleucine and L-phenylalanine were effective at micromolar levels; other effectors operated at mM levels. A regulatory mutant selected for resistance to growth inhibition caused by beta-2-thienylalanine possessed an altered prephenate dehydratase in which a phenomenon of disproportionately low activity at low enzyme concentration was abolished. Inhibition by L-tryptophan was also lost, and activation by allosteric activators was diminished. Not only was sensitivity to feedback inhibition by L-phenylalanine lost, but the mutant enzyme was now activated by this amino acid (a mutation type previously observed in Bacillus subtilis). It remains to be seen whether this type of prephenate dehydratase will prove to be characteristic of all archaebacteria or of some archaebacterial subgroup cluster.

  13. An extreme-halophile archaebacterium possesses the interlock type of prephenate dehydratase characteristic of the Gram-positive eubacteria

    NASA Technical Reports Server (NTRS)

    Jensen, R. A.; d'Amato, T. A.; Hochstein, L. I.

    1988-01-01

    The focal point of phenylalanine biosynthesis is a dehydratase reaction which in different organisms may be prephenate dehydratase, arogenate dehydratase, or cyclohexadienyl dehydratase. Gram-positive, Gram-negative, and cyanobacterial divisions of the eubacterial kingdom exhibit different dehydratase patterns. A new extreme-halophile isolate, which grows on defined medium and is tentatively designated as Halobacterium vallismortis CH-1, possesses the interlock type of prephenate dehydratase present in Gram-positive bacteria. In addition to the conventional sensitivity to feedback inhibition by L-phenylalanine, the phenomenon of metabolic interlock was exemplified by the sensitivity of prephenate dehydratase to allosteric effects produced by extra-pathway (remote) effectors. Thus, L-tryptophan inhibited activity while L-tyrosine, L-methionine, L-leucine and L-isoleucine activated the enzyme. L-Isoleucine and L-phenylalanine were effective at micromolar levels; other effectors operated at mM levels. A regulatory mutant selected for resistance to growth inhibition caused by beta-2-thienylalanine possessed an altered prephenate dehydratase in which a phenomenon of disproportionately low activity at low enzyme concentration was abolished. Inhibition by L-tryptophan was also lost, and activation by allosteric activators was diminished. Not only was sensitivity to feedback inhibition by L-phenylalanine lost, but the mutant enzyme was now activated by this amino acid (a mutation type previously observed in Bacillus subtilis). It remains to be seen whether this type of prephenate dehydratase will prove to be characteristic of all archaebacteria or of some archaebacterial subgroup cluster.

  14. Caenorhabditis elegans immune conditioning with the probiotic bacterium Lactobacillus acidophilus strain NCFM enhances gram-positive immune responses.

    PubMed

    Kim, Younghoon; Mylonakis, Eleftherios

    2012-07-01

    Although the immune response of Caenorhabditis elegans to microbial infections is well established, very little is known about the effects of health-promoting probiotic bacteria on evolutionarily conserved C. elegans host responses. We found that the probiotic Gram-positive bacterium Lactobacillus acidophilus NCFM is not harmful to C. elegans and that L. acidophilus NCFM is unable to colonize the C. elegans intestine. Conditioning with L. acidophilus NCFM significantly decreased the burden of a subsequent Enterococcus faecalis infection in the nematode intestine and prolonged the survival of nematodes exposed to pathogenic strains of E. faecalis and Staphylococcus aureus, including multidrug-resistant (MDR) isolates. Preexposure of nematodes to Bacillus subtilis did not provide any beneficial effects. Importantly, L. acidophilus NCFM activates key immune signaling pathways involved in C. elegans defenses against Gram-positive bacteria, including the p38 mitogen-activated protein kinase pathway (via TIR-1 and PMK-1) and the β-catenin signaling pathway (via BAR-1). Interestingly, conditioning with L. acidophilus NCFM had a minimal effect on Gram-negative infection with Pseudomonas aeruginosa or Salmonella enterica serovar Typhimurium and had no or a negative effect on defense genes associated with Gram-negative pathogens or general stress. In conclusion, we describe a new system for the study of probiotic immune agents and our findings demonstrate that probiotic conditioning with L. acidophilus NCFM modulates specific C. elegans immunity traits.

  15. Oligopolyphenylenevinylene-conjugated oligoelectrolyte membrane insertion molecules selectively disrupt cell envelopes of Gram-positive bacteria.

    PubMed

    Hinks, Jamie; Poh, Wee Han; Chu, Justin Jang Hann; Loo, Joachim Say Chye; Bazan, Guillermo C; Hancock, Lynn E; Wuertz, Stefan

    2015-03-01

    The modification of microbial membranes to achieve biotechnological strain improvement with exogenous small molecules, such as oligopolyphenylenevinylene-conjugated oligoelectrolyte (OPV-COE) membrane insertion molecules (MIMs), is an emerging biotechnological field. Little is known about the interactions of OPV-COEs with their target, the bacterial envelope. We studied the toxicity of three previously reported OPV-COEs with a selection of Gram-negative and Gram-positive organisms and demonstrated that Gram-positive bacteria are more sensitive to OPV-COEs than Gram-negative bacteria. Transmission electron microscopy demonstrated that these MIMs disrupt microbial membranes and that this occurred to a much greater degree in Gram-positive organisms. We used a number of mutants to probe the nature of MIM interactions with the microbial envelope but were unable to align the membrane perturbation effects of these compounds to previously reported membrane disruption mechanisms of, for example, cationic antimicrobial peptides. Instead, the data support the notion that OPV-COEs disrupt microbial membranes through a suspected interaction with diphosphatidylglycerol (DPG), a major component of Gram-positive membranes. The integrity of model membranes containing elevated amounts of DPG was disrupted to a greater extent by MIMs than those prepared from Escherichia coli total lipid extracts alone.

  16. Inactivation of Gram-Positive Bacteria by Novel Phenolic Branched-Chain Fatty Acids.

    PubMed

    Fan, Xuetong; Wagner, Karen; Sokorai, Kimberly J B; Ngo, Helen

    2017-01-01

    Novel phenolic branched-chain fatty acids (PBC-FAs) were evaluated for their antimicrobial properties against both gram-positive ( Listeria innocua , Bacillus subtilis , Enterococcus faecium ) and gram-negative ( Escherichia coli , Salmonella Typhimurium, and Pseudomonas tolaasii ) bacteria. In addition, PBC-FA derivatives, such as PBC-FA methyl ester mixture, methyl-branched fatty acid mixtures, and trimethylsilyl-PBC-FA methyl esters, were synthesized to study the structure activity relationship. Results showed that PBC-FAs were a potent antimicrobial against gram-positive bacteria with MICs of 1.8 to 3.6 μg/ml. The compounds were less effective against gram-negative bacteria. Derivatives of PBC-FAs and an equimolar mixture of oleic acid and phenol all had MICs above 233 μg/ml against both gram-positive and gram-negative bacteria. Comparison of antimicrobial activities of the PBC-FAs with those of the derivatives suggests that the carboxylic group in the fatty acid moiety and the hydroxyl group on the phenol moiety were responsible for the antimicrobial efficacy. Growth curves of L. innocua revealed that PBC-FAs prevented bacterial growth, while MBC-FAs only delayed the onset of rapid growth of L. innocua . Our results demonstrated that the novel PBC-FAs have potential for use as antimicrobials against gram-positive bacteria.

  17. Oligopolyphenylenevinylene-Conjugated Oligoelectrolyte Membrane Insertion Molecules Selectively Disrupt Cell Envelopes of Gram-Positive Bacteria

    PubMed Central

    Poh, Wee Han; Chu, Justin Jang Hann; Loo, Joachim Say Chye; Bazan, Guillermo C.; Hancock, Lynn E.

    2015-01-01

    The modification of microbial membranes to achieve biotechnological strain improvement with exogenous small molecules, such as oligopolyphenylenevinylene-conjugated oligoelectrolyte (OPV-COE) membrane insertion molecules (MIMs), is an emerging biotechnological field. Little is known about the interactions of OPV-COEs with their target, the bacterial envelope. We studied the toxicity of three previously reported OPV-COEs with a selection of Gram-negative and Gram-positive organisms and demonstrated that Gram-positive bacteria are more sensitive to OPV-COEs than Gram-negative bacteria. Transmission electron microscopy demonstrated that these MIMs disrupt microbial membranes and that this occurred to a much greater degree in Gram-positive organisms. We used a number of mutants to probe the nature of MIM interactions with the microbial envelope but were unable to align the membrane perturbation effects of these compounds to previously reported membrane disruption mechanisms of, for example, cationic antimicrobial peptides. Instead, the data support the notion that OPV-COEs disrupt microbial membranes through a suspected interaction with diphosphatidylglycerol (DPG), a major component of Gram-positive membranes. The integrity of model membranes containing elevated amounts of DPG was disrupted to a greater extent by MIMs than those prepared from Escherichia coli total lipid extracts alone. PMID:25576607

  18. Future gazing in the management of multiply drug-resistant Gram-positive infection.

    PubMed

    Wilcox, Mark H

    2009-09-01

    Gram-positive bacteria have evolved to become predominant health care associated pathogens. To meet this challenge, novel approaches to the development, prescribing, and control of antibiotics will be needed. Additional infection control methods must also be explored. This review discusses the challenges posed in particular by methicillin-resistant staphylococci and potential ways forward.

  19. Microbial pathogenicity and virulence mediated by integrons on Gram-positive microorganisms.

    PubMed

    Li, Yanmei; Yang, Ling; Fu, Jie; Yan, Muxia; Chen, Dingqiang; Zhang, Li

    2017-09-18

    Gram-positive microorganisms are one of leading pathogenic microorganisms in public health, including several typical "Super Bugs" as methicillin-resistant Staphylococcus aureus, Klebsiella pneumoniae carbapenemase and vancomycin-resistant enterococci, which caused a increasement of infections, clinical failures and expenses. Regarded as a common genetic element responsible for horizontal gene transfer, integrons are widely distributed in various pathogens considered as a determinant in the acquisition and evolution of antibiotic resistance. Current investigations mainly focus on the distribution of integrons in Gram-negative microorganisms, while the role of integron in antibiotic resistance among Gram-positive microorganisms remains unclear and need investigation. To date, the surveillances of integrons in Gram-positive microorganism have been widely conducted in clinic, community even husbandry. China remains one of the worst country in antibiotics abuse worldwide and considered as a potential area for the prevalence of antimicrobial microorganisms and the occurrence of various 'Super Bugs'. Recently, the surveillance of the occurrence of integron and resistance gene cassettes was conducted in South China during the first 10 years of the 21st century. Referred to the surveillance in South China and other investigation in Asian countries, this review aims to summarize the occurrence, pathogenicity and virulence mediated by integrons in typical Gram-positive microorganisms (Staphylococcus, Enterococcus, Corynebacterium and Streptococcus) and the role of integrons in antibiotic resistance. Copyright © 2017. Published by Elsevier Ltd.

  20. Native and heterologous production of bacteriocins from gram-positive microorganisms.

    PubMed

    Muñoz, Mabel; Jaramillo, Diana; Melendez, Adelina Del Pilar; J Alméciga-Diaz, Carlos; Sánchez, Oscar F

    2011-12-01

    In nature, microorganisms can present several mechanisms for setting intercommunication and defense. One of these mechanisms is related to the production of bacteriocins, which are peptides with antimicrobial activity. Bacteriocins can be found in Gram-positive and Gram-negative bacteria. Nevertheless, bacteriocins produced by Gram-positive bacteria are of particular interest due to the industrial use of several strains that belong to this group, especially lactic acid bacteria (LAB), which have the status of generally recognized as safe (GRAS) microorganisms. In this work, we will review recent tendencies in the field of invention and state of art related to bacteriocin production by Gram-positive microorganism. Hundred-eight patents related to Gram-positive bacteriocin producers have been disclosed since 1965, from which 57% are related bacteriocins derived from Lactococcus, Lactobacillus, Streptococcus, and Pediococcus strains. Surprisingly, patents regarding heterologous bacteriocins production were mainly presented just in the last decade. Although the major application of bacteriocins is concerned to food industry to control spoilage and foodborne bacteria, during the last years bacteriocin applications have been displacing to the diagnosis and treatment of cancer, and plant disease resistance and growth promotion.

  1. Multiplex PCR for colony direct detection of Gram-positive histamine- and tyramine-producing bacteria.

    PubMed

    Coton, Emmanuel; Coton, Monika

    2005-12-01

    Formation of biogenic amines (BA) may occur in fermented foods and beverages due to the amino acid decarboxylase activities of Gram-positive bacteria. These compounds may cause food poisoning and therefore could imply food exportation problems. A set of consensual primers based on histidine decarboxylase gene (hdc) sequences of different bacteria was designed for the detection of histamine-producing Gram-positive bacteria. A multiplex PCR based on these hdc primers and recently designed primers targeting the tyrosine decarboxylase (tyrdc) gene was created. A third set of primers targeting the 16S rRNA gene of eubacteria was also used as an internal control. This multiplex PCR was performed on extracted DNA as well as directly on cell colonies. The results obtained show that this new molecular tool allowed for the detection of Gram-positive histamine- and/or tyramine-producing bacteria. The use of this molecular tool for early and rapid detection of Gram-positive BA-producing bacteria is of interest in evaluating the potential of cultured indigenous strains to produce biogenic amines in a fermented food product as well as to validate the innocuity of potential starter strains in the food industry.

  2. Antimicrobial and Efflux Pump Inhibitory Activity of Caffeoylquinic Acids from Artemisia absinthium against Gram-Positive Pathogenic Bacteria

    PubMed Central

    Fiamegos, Yiannis C.; Kastritis, Panagiotis L.; Exarchou, Vassiliki; Han, Haley; Bonvin, Alexandre M. J. J.; Vervoort, Jacques; Lewis, Kim; Hamblin, Michael R.; Tegos, George P.

    2011-01-01

    Background Traditional antibiotics are increasingly suffering from the emergence of multidrug resistance amongst pathogenic bacteria leading to a range of novel approaches to control microbial infections being investigated as potential alternative treatments. One plausible antimicrobial alternative could be the combination of conventional antimicrobial agents/antibiotics with small molecules which block multidrug efflux systems known as efflux pump inhibitors. Bioassay-driven purification and structural determination of compounds from plant sources have yielded a number of pump inhibitors which acted against gram positive bacteria. Methodology/Principal Findings In this study we report the identification and characterization of 4′,5′-O-dicaffeoylquinic acid (4′,5′-ODCQA) from Artemisia absinthium as a pump inhibitor with a potential of targeting efflux systems in a wide panel of Gram-positive human pathogenic bacteria. Separation and identification of phenolic compounds (chlorogenic acid, 3′,5′-ODCQA, 4′,5′-ODCQA) was based on hyphenated chromatographic techniques such as liquid chromatography with post column solid-phase extraction coupled with nuclear magnetic resonance spectroscopy and mass spectroscopy. Microbial susceptibility testing and potentiation of well know pump substrates revealed at least two active compounds; chlorogenic acid with weak antimicrobial activity and 4′,5′-ODCQA with pump inhibitory activity whereas 3′,5′-ODCQA was ineffective. These intitial findings were further validated with checkerboard, berberine accumulation efflux assays using efflux-related phenotypes and clinical isolates as well as molecular modeling methodology. Conclusions/Significance These techniques facilitated the direct analysis of the active components from plant extracts, as well as dramatically reduced the time needed to analyze the compounds, without the need for prior isolation. The calculated energetics of the docking poses supported the

  3. Amplifiable DNA from Gram-negative and Gram-positive bacteria by a low strength pulsed electric field method

    PubMed Central

    Vitzthum, Frank; Geiger, Georg; Bisswanger, Hans; Elkine, Bentsian; Brunner, Herwig; Bernhagen, Jürgen

    2000-01-01

    An efficient electric field-based procedure for cell disruption and DNA isolation is described. Isoosmotic suspensions of Gram-negative and Gram-positive bacteria were treated with pulsed electric fields of <60 V/cm. Pulses had an exponential decay waveform with a time constant of 3.4 µs. DNA yield was linearly dependent on time or pulse number, with several thousand pulses needed. Electrochemical side-effects and electrophoresis were minimal. The lysates contained non-fragmented DNA which was readily amplifiable by PCR. As the method was not limited to samples of high specific resistance, it should be applicable to physiological fluids and be useful for genomic and DNA diagnostic applications. PMID:10734214

  4. Antimicrobial growth promoters used in animal feed: effects of less well known antibiotics on gram-positive bacteria.

    PubMed

    Butaye, Patrick; Devriese, Luc A; Haesebrouck, Freddy

    2003-04-01

    There are not many data available on antibiotics used solely in animals and almost exclusively for growth promotion. These products include bambermycin, avilamycin, efrotomycin, and the ionophore antibiotics (monensin, salinomycin, narasin, and lasalocid). Information is also scarce for bacitracin used only marginally in human and veterinary medicine and for streptogramin antibiotics. The mechanisms of action of and resistance mechanisms against these antibiotics are described. Special emphasis is given to the prevalence of resistance among gram-positive bacteria isolated from animals and humans. Since no susceptibility breakpoints are available for most of the antibiotics discussed, an alternative approach to the interpretation of MICs is presented. Also, some pharmacokinetic data and information on the influence of these products on the intestinal flora are presented.

  5. Antimicrobial Growth Promoters Used in Animal Feed: Effects of Less Well Known Antibiotics on Gram-Positive Bacteria

    PubMed Central

    Butaye, Patrick; Devriese, Luc A.; Haesebrouck, Freddy

    2003-01-01

    There are not many data available on antibiotics used solely in animals and almost exclusively for growth promotion. These products include bambermycin, avilamycin, efrotomycin, and the ionophore antibiotics (monensin, salinomycin, narasin, and lasalocid). Information is also scarce for bacitracin used only marginally in human and veterinary medicine and for streptogramin antibiotics. The mechanisms of action of and resistance mechanisms against these antibiotics are described. Special emphasis is given to the prevalence of resistance among gram-positive bacteria isolated from animals and humans. Since no susceptibility breakpoints are available for most of the antibiotics discussed, an alternative approach to the interpretation of MICs is presented. Also, some pharmacokinetic data and information on the influence of these products on the intestinal flora are presented. PMID:12692092

  6. Reliability of Disk Diffusion Test Results for the Antimicrobial Susceptibility Testing of Nosocomial Gram-positive Microorganisms: Is E-test Method Better?

    PubMed Central

    Khalili, Hossein; Soltani, Rasool; Negahban, Sorrosh; Abdollahi, Alireza; Gholami, Keirollah

    2012-01-01

    Disk diffusion test is the usual applicable method for assessing the antimicrobial susceptibility pattern in most institutions and hospitals. The aim of this study was to determine the reliability of resistant-reported results of disk diffusion test for 6 routinely used antibiotics against Gram-positive microorganisms of nosocomial origin, using E-test method. Over a 1-year period, clinical specimens (e.g. blood, tracheal secretions, wound secretions, urine, etc.) were obtained from hospitalized patients with defined nosocomial infection and were cultured. Isolated Gram-positive bacteria underwent disk diffusion test for cephalothin, oxacillin, clindamycin, ciprofloxacin, vancomycin, teicoplanin (only for Enterococci), and meropenem antibiotics. E-test method was performed for all isolates resistant or intermediately sensitive to the disks of any mentioned antibiotics. Data showed compatible results of disk diffusion test with the results of E-test method for cephalothin, oxacillin, ciprofloxacin, vancomycin, and teicoplanin. None of ciprofloxacin- and vancomycin-resistant isolates in disk diffusion test showed sensitivity in E-test method. Significant differences between the results of disk diffusion and E-test methods were observed for clindamycin and meropenem against S.aureus (p = 0.01 and 0.04, respectively) and Enterococcus spp (p = 0.03 and 0.02, respectively). In order to increase the reliability of antimicrobial susceptibility results, it is recommended to perform E-test for nosocomial Gram-positive microorganisms that show antibiotic resistance by disk diffusion test and it is more important for clindamycin and meropenem. PMID:24250479

  7. Reliability of Disk Diffusion Test Results for the Antimicrobial Susceptibility Testing of Nosocomial Gram-positive Microorganisms: Is E-test Method Better?

    PubMed

    Khalili, Hossein; Soltani, Rasool; Negahban, Sorrosh; Abdollahi, Alireza; Gholami, Keirollah

    2012-01-01

    Disk diffusion test is the usual applicable method for assessing the antimicrobial susceptibility pattern in most institutions and hospitals. The aim of this study was to determine the reliability of resistant-reported results of disk diffusion test for 6 routinely used antibiotics against Gram-positive microorganisms of nosocomial origin, using E-test method. Over a 1-year period, clinical specimens (e.g. blood, tracheal secretions, wound secretions, urine, etc.) were obtained from hospitalized patients with defined nosocomial infection and were cultured. Isolated Gram-positive bacteria underwent disk diffusion test for cephalothin, oxacillin, clindamycin, ciprofloxacin, vancomycin, teicoplanin (only for Enterococci), and meropenem antibiotics. E-test method was performed for all isolates resistant or intermediately sensitive to the disks of any mentioned antibiotics. Data showed compatible results of disk diffusion test with the results of E-test method for cephalothin, oxacillin, ciprofloxacin, vancomycin, and teicoplanin. None of ciprofloxacin- and vancomycin-resistant isolates in disk diffusion test showed sensitivity in E-test method. Significant differences between the results of disk diffusion and E-test methods were observed for clindamycin and meropenem against S.aureus (p = 0.01 and 0.04, respectively) and Enterococcus spp (p = 0.03 and 0.02, respectively). In order to increase the reliability of antimicrobial susceptibility results, it is recommended to perform E-test for nosocomial Gram-positive microorganisms that show antibiotic resistance by disk diffusion test and it is more important for clindamycin and meropenem.

  8. [Bacteria isolated from surgical infections and its susceptibilities to antimicrobial agents--special references to bacteria isolated between April 2009 and March 2010].

    PubMed

    Shinagawa, Nagao; Osanai, Hiroyuki; Hirata, Koichi; Furuhata, Tomohisa; Mizukuchi, Tohru; Yanai, Yoshiyuki; Hata, Fumitake; Taniguchi, Masaaki; Sasaki, Kazuaki; Someya, Tetsufumi; Sasaki, Kazunori; Oono, Keisuke; Mizuno, Isamu; Shamoto, Tomoya; Fukui, Takuji; Tokita, Shoji; Nakamura, Masashi; Mashita, Keiji; Shibuya, Hitoshi; Tanaka, Moritsugu; Hasegawa, Itaru; Kimura, Masami; Oshima, Hideki; Maeda, Hideki; Ishikawa, Syu; Mukaiya, Mitsuhiro; Kihara, Chikasi; Mizuno, Akira; Watabe, Kosho; Iwai, Akihiko; Saito, Takaaki; Hoshikawa, Tsuyoshi; Kimura, Hitoshi; Moori, Noriaki; Sumita, Naoki; Jae-Hoon, Yoo; Kubo, Shoji; Lee, Shigeru; Aikawa, Naoki; Sekine, Kazuhiko; Abe, Shinya; Oomura, Toru; Takeyama, Hiromitsu; Wakasugi, Takehiro; Kobayashi, Yasuhito; Tsuji, Takeshi; Yamaue, Hiroki; Ozawa, Satoru; Takesue, Yoshio; Fujiwara, Toshiyoshi; Tsumura, Hiroaki; Kimura, Hideyuki; Yokoyama, Takashi; Iwagaki, Hiromi; Takeuchi, Hitoshi; Tanakaya, Kouji; Sueda, Taijiro; Hiyama, Eiso; Murakami, Yoshiaki; Ohge, Hiroki; Uemura, Kenichiro; Yasunami, Yoichi; Sasaki, Takamitsu

    2011-06-01

    Bacteria isolated from surgical infections during the period from April 2009 to March 2010 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 671 strains including 16 strains of Candida spp. were isolated from 174 (79.1%) of 220 patients with surgical infections. Four hundred and eleven strains were isolated from primary infections, and 244 strains were isolated from surgical site infection. From primary infections, anaerobic Gram-negative bacteria were predominant, followed by aerobic Gram-negative bacteria, while from surgical site infection aerobic Gram-positive bacteria were predominant, followed by anaerobic Gram-negative bacteria. Among aerobic Gram-positive bacteria, the isolation rate of Enterococcus spp. was highest, followed by Streptococcus spp., and Staphylococcus spp. in this order, from primary infections, while Enterococcus spp. was highest, followed by Staphylococcus spp. from surgical site infection. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae, Enterobacter cloacae and Pseudomonas aeruginosa, in this order, and from surgical site infection, E. coli was most predominantly isolated, followed by P. aeruginosa and E. cloacae. Among anaerobic Gram-positive bacteria, the isolation rate of Eggerthella lenta was the highest from primary infections, followed by Parvimonas micra, Streptococcus constellatus and Finegoldia magna, and from surgical site infection, E. lenta was most predominantly isolated. Among anaerobic Gram-negative bacteria, the isolation rate of Bilophila wadsworthia was the highest from primary infections, followed by Bacteroides fragilis, Bacteroides ovatus and Bacteroides thetaiotaomicron, and from surgical site infection, B. fragilis was most predominantly isolated, followed by B. ovatus, B. wadsworthia and B. thetaiotaomicron, in this order. In this series, we noticed no

  9. Small regulatory RNAs from low-GC Gram-positive bacteria

    PubMed Central

    Brantl, Sabine; Brückner, Reinhold

    2014-01-01

    Small regulatory RNAs (sRNAs) that act by base-pairing were first discovered in so-called accessory DNA elements—plasmids, phages, and transposons—where they control replication, maintenance, and transposition. Since 2001, a huge body of work has been performed to predict and identify sRNAs in a multitude of bacterial genomes. The majority of chromosome-encoded sRNAs have been investigated in E. coli and other Gram-negative bacteria. However, during the past five years an increasing number of sRNAs were found in Gram-positive bacteria. Here, we outline our current knowledge on chromosome-encoded sRNAs from low-GC Gram-positive species that act by base-pairing, i.e., an antisense mechanism. We will focus on sRNAs with known targets and defined regulatory mechanisms with special emphasis on Bacillus subtilis. PMID:24576839

  10. Ubiquitous detection of gram-positive bacteria with bioorthogonal magnetofluorescent nanoparticles.

    PubMed

    Chung, Hyun Jung; Reiner, Thomas; Budin, Ghyslain; Min, Changwook; Liong, Monty; Issadore, David; Lee, Hakho; Weissleder, Ralph

    2011-11-22

    The ability to rapidly diagnose gram-positive pathogenic bacteria would have far reaching biomedical and technological applications. Here we describe the bioorthogonal modification of small molecule antibiotics (vancomycin and daptomycin), which bind to the cell wall of gram-positive bacteria. The bound antibiotics conjugates can be reacted orthogonally with tetrazine-modified nanoparticles, via an almost instantaneous cycloaddition, which subsequently renders the bacteria detectable by optical or magnetic sensing. We show that this approach is specific, selective, fast and biocompatible. Furthermore, it can be adapted to the detection of intracellular pathogens. Importantly, this strategy enables detection of entire classes of bacteria, a feat that is difficult to achieve using current antibody approaches. Compared to covalent nanoparticle conjugates, our bioorthogonal method demonstrated 1-2 orders of magnitude greater sensitivity. This bioorthogonal labeling method could ultimately be applied to a variety of other small molecules with specificity for infectious pathogens, enabling their detection and diagnosis.

  11. [Production of bacteriocins by gram-positive bacteria and the mechanisms of transcriptional regulation].

    PubMed

    Kotel'nikova, E A; Gel'fand, M S

    2002-06-01

    The mechanisms of production of bacteriocins in Gram-positive bacteria and the main distinctions of these bacteriocins from the bacteriocins of Gram-negative bacteria (colicins) are outlined. A classification of antibacterial peptides is presented, and most of known class I and II peptides are pointed out. In Gram-positive bacteria, the cases of bacteriocin-associated quorum sensing are examined. For these cases, the structure of loci containing the genes of regulatory systems, transport, immunity, processing, and posttranslational modification of antibacterial peptides are described. All known regulatory sites for class II bacteriocins are presented. A description of the putative regulatory sites found by us and their classification are provided. The evolutionary tree of transcriptional response regulators is shown to correspond to the tree of their recognition sites.

  12. Peptide signaling in Staphylococcus aureus and other Gram-positive bacteria.

    PubMed

    Lyon, Gholson J; Novick, Richard P

    2004-09-01

    There are two basic types of bacterial communication systems--those in which the signal is directed solely at other organisms and those in which the signal is sensed by the producing organism as well. The former are involved primarily in conjugation; the latter in adaptation to the environment. Gram-positive bacteria use small peptides for both types of signaling, whereas Gram-negative bacteria use homoserine lactones. Since adaptation signals are autoinducers the response is population-density-dependent and has been referred to as "quorum-sensing". Gram-negative bacteria internalize the signals which act upon an intracellular receptor, whereas Gram-positive bacteria use them as ligands for the extracellular receptor of a two-component signaling module. In both cases, the signal activates a complex adaptation response involving many genes.

  13. From environmental signals to regulators: modulation of biofilm development in Gram-positive bacteria.

    PubMed

    Mhatre, Eisha; Monterrosa, Ramses Gallegos; Kovács, Akos T

    2014-07-01

    Bacterial lifestyle is influenced by environmental signals, and many differentiation processes in bacteria are governed by the threshold concentrations of molecules present in their niche. Biofilm is one such example where bacteria in their sessile state adapt to a lifestyle that causes several adaptive alterations in the population. Here, a brief overview is given on a variety of environmental signals that bias biofilm development in Gram-positive bacteria, including nutrient conditions, self- and heterologously produced substances, like quorum sensing and host produced molecules. The Gram-positive model organism, Bacillus subtilis is a superb example to illustrate how distinct signals activate sensor proteins that integrate the environmental signals towards global regulators related to biofilm formation. The role of reduced oxygen level, polyketides, antimicrobials, plant secreted carbohydrates, plant cell derived polymers, glycerol, and osmotic conditions are discussed during the transcriptional activation of biofilm related genes in B. subtilis. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Antibacterial properties of sophorolipid-modified gold surfaces against Gram positive and Gram negative pathogens.

    PubMed

    Valotteau, Claire; Banat, Ibrahim M; Mitchell, Christopher A; Lydon, Helen; Marchant, Roger; Babonneau, Florence; Pradier, Claire-Marie; Baccile, Niki; Humblot, Vincent

    2017-09-01

    Sophorolipids are bioderived glycolipids displaying interesting antimicrobial properties. We show that they can be used to develop biocidal monolayers against Listeria ivanovii, a Gram-positive bacterium. The present work points out the dependence between the surface density and the antibacterial activity of grafted sophorolipids. It also emphasizes the broad spectrum of activity of these coatings, demonstrating their potential against both Gram-positive strains (Enteroccocus faecalis, Staphylococcus epidermidis, Streptococcus pyogenes) and Gram-negative strains (Escherichia coli, Pseudomonas aeruginosa and Salmonella typhymurium). After exposure to sophorolipids grafted onto gold, all these bacterial strains show a significant reduction in viability resulting from membrane damage as evidenced by fluorescent labelling and SEM-FEG analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Blue green alga mediated synthesis of gold nanoparticles and its antibacterial efficacy against Gram positive organisms.

    PubMed

    Suganya, K S Uma; Govindaraju, K; Kumar, V Ganesh; Dhas, T Stalin; Karthick, V; Singaravelu, G; Elanchezhiyan, M

    2015-02-01

    Biofunctionalized gold nanoparticles (AuNPs) play an important role in design and development of nanomedicine. Synthesis of AuNPs from biogenic materials is environmentally benign and possesses high bacterial inhibition and bactericidal properties. In the present study, blue green alga Spirulina platensis protein mediated synthesis of AuNPs and its antibacterial activity against Gram positive bacteria is discussed. AuNPs were characterized using Ultraviolet-visible (UV-vis) spectroscopy, Fluorescence spectroscopy, Fourier Transform-Infrared (FTIR) spectroscopy, Raman spectroscopy, High Resolution-Transmission Electron Microscopy (HR-TEM) and Energy Dispersive X-ray analysis (EDAX). Stable, well defined AuNPs of smaller and uniform shape with an average size of ~ 5 nm were obtained. The antibacterial efficacy of protein functionalized AuNPs were tested against Gram positive organisms Bacillus subtilis and Staphylococcus aureus.

  16. Novel Acylphosphate Mimics that Target PlsY, an Essential Acyltransferase in Gram-Positive Bacteria

    PubMed Central

    Grimes, Kimberly D.; Lu, Ying-Jie; Zhang, Yong-Mei; Luna, Vicki A.; Hurdle, Julian G.; Carson, Elizabeth I.; Qi, Jianjun; Kudrimoti, Sucheta; Rock, Charles O.

    2009-01-01

    PlsY is a recently discovered acyltransferase that executes an essential step in membrane phospholipid biosynthesis in Gram-positive bacteria. Using a bioisosteric replacement approach to generate substrate-based inhibitors of PlsY as potential novel antibacterial agents, a series of stabilized acylphosphate mimetics, including acylphosphonates, acyl αα,-difluoromethyl phosphonates, acyl phosphoramides, reverse amide phosphonates, acylsulfamates and acylsulfamides were designed and synthesized. Several acyl phosphonates, phosphoramides and sulfamates were identified as inhibitors of PlsY from Streptococcus pneumoniae and Bacillus anthracis. As anticipated, these inhibitors were competitive inhibitors with respect to the acylphosphate substrate. Antimicrobial testing showed the inhibitors to have generally weak anti Gram-positive activity with the exception of some acyl phosphonates, reverse amide phosphonates, and acylsulfamates that had potent activity against multiple strains of Bacillus anthracis. PMID:19016283

  17. Mid-infrared spectroscopic assessment of nanotoxicity in gram-negative vs. gram-positive bacteria.

    PubMed

    Heys, Kelly A; Riding, Matthew J; Strong, Rebecca J; Shore, Richard F; Pereira, M Glória; Jones, Kevin C; Semple, Kirk T; Martin, Francis L

    2014-03-07

    Nanoparticles appear to induce toxic effects through a variety of mechanisms including generation of reactive oxygen species (ROS), physical contact with the cell membrane and indirect catalysis due to remnants from manufacture. The development and subsequent increasing usage of nanomaterials has highlighted a growing need to characterize and assess the toxicity of nanoparticles, particularly those that may have detrimental health effects such as carbon-based nanomaterials (CBNs). Due to interactions of nanoparticles with some reagents, many traditional toxicity tests are unsuitable for use with CBNs. Infrared (IR) spectroscopy is a non-destructive, high throughput technique, which is unhindered by such problems. We explored the application of IR spectroscopy to investigate the effects of CBNs on Gram-negative (Pseudomonas fluorescens) and Gram-positive (Mycobacterium vanbaalenii PYR-1) bacteria. Two types of IR spectroscopy were compared: attenuated total reflection Fourier-transform infrared (ATR-FTIR) and synchrotron radiation-based FTIR (SR-FTIR) spectroscopy. This showed that Gram-positive and Gram-negative bacteria exhibit differing alterations when exposed to CBNs. Gram-positive bacteria appear more resistant to these agents and this may be due to the protection afforded by their more sturdy cell wall. Markers of exposure also vary according to Gram status; Amide II was consistently altered in Gram-negative bacteria and carbohydrate altered in Gram-positive bacteria. ATR-FTIR and SR-FTIR spectroscopy could both be applied to extract biochemical alterations induced by each CBN that were consistent across the two bacterial species; these may represent potential biomarkers of nanoparticle-induced alterations. Vibrational spectroscopy approaches may provide a novel means of fingerprinting the effects of CBNs in target cells.

  18. Progress in the Development of Effective Vaccines to Prevent Selected Gram Positive Bacterial Infections

    PubMed Central

    Bronze, Michael S.; Dale, James B.

    2010-01-01

    Infections due to virulent gram positive bacteria, such as Staphylococcus aureus, group B streptococci and group A streptococci remain significant causes of morbidity and mortality despite progress in antimicrobial therapy. Despite significant advances in the understanding of the pathogenesis of infection due to these organisms, there are only limited strategies to prevent infection. In this paper, we review efforts to develop safe and effective vaccines that would prevent infections due to these 3 pathogens. PMID:20697258

  19. Regulation of carbon metabolism in gram-positive bacteria by protein phosphorylation.

    PubMed

    Deutscher, J; Fischer, C; Charrier, V; Galinier, A; Lindner, C; Darbon, E; Dossonnet, V

    1997-01-01

    The main function of the bacterial phosphotransferase system is to transport and to phosphorylate mono- and disaccharides as well as sugar alcohols. However, the phosphotransferase system is also involved in regulation of carbon metabolism. In Gram-positive bacteria, it is implicated in carbon catabolite repression and regulation of expression of catabolic genes by controlling either catabolic enzyme activities, transcriptional activators or antiterminators. All these different regulations follow a protein phosphorylation mechanism.

  20. Gram positive and Gram negative bacteria differ in their sensitivity to cold plasma

    PubMed Central

    Mai-Prochnow, Anne; Clauson, Maryse; Hong, Jungmi; Murphy, Anthony B.

    2016-01-01

    Cold atmospheric-pressure plasma (CAP) is a relatively new method being investigated for antimicrobial activity. However, the exact mode of action is still being explored. Here we report that CAP efficacy is directly correlated to bacterial cell wall thickness in several species. Biofilms of Gram positive Bacillus subtilis, possessing a 55.4 nm cell wall, showed the highest resistance to CAP, with less than one log10 reduction after 10 min treatment. In contrast, biofilms of Gram negative Pseudomonas aeruginosa, possessing only a 2.4 nm cell wall, were almost completely eradicated using the same treatment conditions. Planktonic cultures of Gram negative Pseudomonas libanensis also had a higher log10 reduction than Gram positive Staphylococcus epidermidis. Mixed species biofilms of P. aeruginosa and S. epidermidis showed a similar trend of Gram positive bacteria being more resistant to CAP treatment. However, when grown in co-culture, Gram negative P. aeruginosa was more resistant to CAP overall than as a mono-species biofilm. Emission spectra indicated OH and O, capable of structural cell wall bond breakage, were present in the plasma. This study indicates that cell wall thickness correlates with CAP inactivation times of bacteria, but cell membranes and biofilm matrix are also likely to play a role. PMID:27934958

  1. Gram positive and Gram negative bacteria differ in their sensitivity to cold plasma.

    PubMed

    Mai-Prochnow, Anne; Clauson, Maryse; Hong, Jungmi; Murphy, Anthony B

    2016-12-09

    Cold atmospheric-pressure plasma (CAP) is a relatively new method being investigated for antimicrobial activity. However, the exact mode of action is still being explored. Here we report that CAP efficacy is directly correlated to bacterial cell wall thickness in several species. Biofilms of Gram positive Bacillus subtilis, possessing a 55.4 nm cell wall, showed the highest resistance to CAP, with less than one log10 reduction after 10 min treatment. In contrast, biofilms of Gram negative Pseudomonas aeruginosa, possessing only a 2.4 nm cell wall, were almost completely eradicated using the same treatment conditions. Planktonic cultures of Gram negative Pseudomonas libanensis also had a higher log10 reduction than Gram positive Staphylococcus epidermidis. Mixed species biofilms of P. aeruginosa and S. epidermidis showed a similar trend of Gram positive bacteria being more resistant to CAP treatment. However, when grown in co-culture, Gram negative P. aeruginosa was more resistant to CAP overall than as a mono-species biofilm. Emission spectra indicated OH and O, capable of structural cell wall bond breakage, were present in the plasma. This study indicates that cell wall thickness correlates with CAP inactivation times of bacteria, but cell membranes and biofilm matrix are also likely to play a role.

  2. Class D β-lactamases do exist in Gram-positive bacteria

    DOE PAGES

    Toth, Marta; Antunes, Nuno Tiago; Stewart, Nichole K.; ...

    2015-11-09

    Production of β-lactamases of one of four molecular classes (A, B, C and D) is the major mechanism of bacterial resistance to β-lactams, the largest class of antibiotics, which have saved countless lives since their inception 70 years ago. Although several hundred efficient class D enzymes have been identified in Gram-negative pathogens over the last four decades, none have been reported in Gram-positive bacteria. Here we demonstrate that efficient class D β-lactamases capable of hydrolyzing a wide array of β-lactam substrates are widely disseminated in various species of environmental Gram-positive organisms. Class D enzymes of Gram-positive bacteria have a distinctmore » structural architecture and employ a unique substrate-binding mode that is quite different from that of all currently known class A, C and D β-lactamases. In conclusion, these enzymes thus constitute a previously unknown reservoir of novel antibiotic-resistance enzymes.« less

  3. Critical cell wall hole size for lysis in Gram-positive bacteria

    NASA Astrophysics Data System (ADS)

    Mitchell, Gabriel; Wiesenfeld, Kurt; Nelson, Daniel; Weitz, Joshua

    2013-03-01

    Gram-positive bacteria transport molecules necessary for their survival through holes in their cell wall. The holes in cell walls need to be large enough to let critical nutrients pass through. However, the cell wall must also function to prevent the bacteria's membrane from protruding through a large hole into the environment and lysing the cell. As such, we hypothesize that there exists a range of cell wall hole sizes that allow for molecule transport but prevent membrane protrusion. Here we develop and analyze a biophysical theory of the response of a Gram-positive cell's membrane to the formation of a hole in the cell wall. We predict a critical hole size in the range 15-24nm beyond which lysis occurs. To test our theory, we measured hole sizes in Streptococcus pyogenes cells undergoing enzymatic lysis via transmission electron microscopy. The measured hole sizes are in strong agreement with our theoretical prediction. Together, the theory and experiments provide a means to quantify the mechanisms of death of Gram-positive cells via enzymatically mediated lysis and provides insight into the range of cell wall hole sizes compatible with bacterial homeostasis.

  4. Widespread abundance of functional bacterial amyloid in mycolata and other gram-positive bacteria.

    PubMed

    Jordal, Peter Bruun; Dueholm, Morten Simonsen; Larsen, Poul; Petersen, Steen Vang; Enghild, Jan Johannes; Christiansen, Gunna; Højrup, Peter; Nielsen, Per Halkjaer; Otzen, Daniel Erik

    2009-06-01

    Until recently, extracellular functional bacterial amyloid (FuBA) has been detected and characterized in only a few bacterial species, including Escherichia coli, Salmonella, and the gram-positive organism Streptomyces coelicolor. Here we probed gram-positive bacteria with conformationally specific antibodies and revealed the existence of FuBA in 12 of 14 examined mycolata species, as well as six other distantly related species examined belonging to the phyla Actinobacteria and Firmicutes. Most of the bacteria produced extracellular fimbriae, sometimes copious amounts of them, and in two cases large extracellular fibrils were also produced. In three cases, FuBA was revealed only after extensive removal of extracellular material by saponification, indicating that there is integrated attachment within the cellular envelope. Spores of species in the genera Streptomyces, Bacillus, and Nocardia were all coated with amyloids. FuBA was purified from Gordonia amarae (from the cell envelope) and Geodermatophilus obscurus, and they had the morphology, tinctorial properties, and beta-rich structure typical of amyloid. The presence of approximately 9-nm-wide amyloids in the cell envelope of G. amarae was visualized by transmission electron microscopy analysis. We conclude that amyloid is widespread among gram-positive bacteria and may in many species constitute a hitherto overlooked integral part of the spore and the cellular envelope.

  5. Widespread Abundance of Functional Bacterial Amyloid in Mycolata and Other Gram-Positive Bacteria▿

    PubMed Central

    Jordal, Peter Bruun; Dueholm, Morten Simonsen; Larsen, Poul; Petersen, Steen Vang; Enghild, Jan Johannes; Christiansen, Gunna; Højrup, Peter; Nielsen, Per Halkjær; Otzen, Daniel Erik

    2009-01-01

    Until recently, extracellular functional bacterial amyloid (FuBA) has been detected and characterized in only a few bacterial species, including Escherichia coli, Salmonella, and the gram-positive organism Streptomyces coelicolor. Here we probed gram-positive bacteria with conformationally specific antibodies and revealed the existence of FuBA in 12 of 14 examined mycolata species, as well as six other distantly related species examined belonging to the phyla Actinobacteria and Firmicutes. Most of the bacteria produced extracellular fimbriae, sometimes copious amounts of them, and in two cases large extracellular fibrils were also produced. In three cases, FuBA was revealed only after extensive removal of extracellular material by saponification, indicating that there is integrated attachment within the cellular envelope. Spores of species in the genera Streptomyces, Bacillus, and Nocardia were all coated with amyloids. FuBA was purified from Gordonia amarae (from the cell envelope) and Geodermatophilus obscurus, and they had the morphology, tinctorial properties, and β-rich structure typical of amyloid. The presence of approximately 9-nm-wide amyloids in the cell envelope of G. amarae was visualized by transmission electron microscopy analysis. We conclude that amyloid is widespread among gram-positive bacteria and may in many species constitute a hitherto overlooked integral part of the spore and the cellular envelope. PMID:19395568

  6. Acting antisense: plasmid- and chromosome-encoded sRNAs from Gram-positive bacteria.

    PubMed

    Brantl, Sabine

    2012-07-01

    sRNAs that act by base pairing were first discovered in plasmids, phages and transposons, where they control replication, maintenance and transposition. Since 2001, however, computational searches were applied that led to the discovery of a plethora of sRNAs in bacterial chromosomes. Whereas the majority of these chromsome-encoded sRNAs have been investigated in Escherichia coli, Salmonella and other Gram-negative bacteria, only a few well-studied examples are known from Gram-positive bacteria. Here, the author summarizes our current knowledge on plasmid- and chromosome-encoded sRNAs from Gram-positive species, thereby focusing on regulatory mechanisms used by these RNAs and their biological role in complex networks. Furthermore, regulatory factors that control the expression of these RNAs will be discussed and differences between sRNAs from Gram-positive and Gram-negative bacteria highlighted. The main emphasis of this review is on sRNAs that act by base pairing (i.e., by an antisense mechanism). Thereby, both plasmid-encoded and chromosome-encoded sRNAs will be considered.

  7. Ambuic acid inhibits the biosynthesis of cyclic peptide quormones in gram-positive bacteria.

    PubMed

    Nakayama, Jiro; Uemura, Yumi; Nishiguchi, Kenzo; Yoshimura, Norito; Igarashi, Yasuhiro; Sonomoto, Kenji

    2009-02-01

    Quorum sensing is a cell-density-dependent regulatory system in gram-positive bacteria and is often regulated by cyclic peptides called "quormones," which function as extracellular communication signals. With an aim to discover an antipathogenic agent targeting quorum sensing in gram-positive bacteria, we screened 153 samples of fungal butanol extracts with the guidance of the inhibition of quorum-sensing-mediated gelatinase production in Enterococcus faecalis. Following the screenings, we found that ambuic acid, a known secondary fungal metabolite, inhibited the quorum-sensing-mediated gelatinase production without influencing the growth of E. faecalis. We further demonstrated that ambuic acid targeted the biosynthesis of a cyclic peptide quormone called gelatinase biosynthesis-activating pheromone. Furthermore, ambuic acid also inhibited the biosynthesis of the cyclic peptide quormones of Staphylococcus aureus and Listeria innocua. These results suggest the potential use of ambuic acid as a lead compound of antipathogenic drugs that target the quorum-sensing-mediated virulence expression of gram-positive bacteria.

  8. [Strategies for management of resistant Gram-positive infections: from S. pneumoniae to MRSA].

    PubMed

    Cristini, Francesco

    2007-09-01

    S. pneumoniae and methicillin-resistant S. aureus are the main Gram-positive pathogens responsible for severe infections. In the context of community infections S. pneumoniae is the leading Gram-positive pathogen causing severe infections such as purulent meningitis and pneumonia. The typical pattern of antibiotic sensitivity of this bacterium, frequently resistant to macrolides and with significantly reduced sensitivity to penicillin, is only a relative therapeutic problem in that the preserved sensitivity to third-generation cephalosporins and respiratory fluoroquinolones is sufficient to make these antibiotics valid therapeutic solutions without having to use the latest generation of drugs. On the other hand, methicillin-resistant S. aureus, one of the main bacteria responsible for nosocomial infections such as bacteraemia and respiratory tract infections in severely ill patients, is a more challenging therapeutic problem since, historically, the therapeutic options available in clinical practice have been fewer and essentially limited to glycopeptides. The recent availability of oxazolidinones and the pharmacologically more rational and appropriate use of the glycopeptides have undoubtedly brought substantial benefits; the imminent introduction of new molecules active against Gram-positive pathogens will certainly make an important contribution, although their use in clinical practice will need to be monitored.

  9. Gram positive and Gram negative bacteria differ in their sensitivity to cold plasma

    NASA Astrophysics Data System (ADS)

    Mai-Prochnow, Anne; Clauson, Maryse; Hong, Jungmi; Murphy, Anthony B.

    2016-12-01

    Cold atmospheric-pressure plasma (CAP) is a relatively new method being investigated for antimicrobial activity. However, the exact mode of action is still being explored. Here we report that CAP efficacy is directly correlated to bacterial cell wall thickness in several species. Biofilms of Gram positive Bacillus subtilis, possessing a 55.4 nm cell wall, showed the highest resistance to CAP, with less than one log10 reduction after 10 min treatment. In contrast, biofilms of Gram negative Pseudomonas aeruginosa, possessing only a 2.4 nm cell wall, were almost completely eradicated using the same treatment conditions. Planktonic cultures of Gram negative Pseudomonas libanensis also had a higher log10 reduction than Gram positive Staphylococcus epidermidis. Mixed species biofilms of P. aeruginosa and S. epidermidis showed a similar trend of Gram positive bacteria being more resistant to CAP treatment. However, when grown in co-culture, Gram negative P. aeruginosa was more resistant to CAP overall than as a mono-species biofilm. Emission spectra indicated OH and O, capable of structural cell wall bond breakage, were present in the plasma. This study indicates that cell wall thickness correlates with CAP inactivation times of bacteria, but cell membranes and biofilm matrix are also likely to play a role.

  10. Screening beneficial rhizobacteria from Spartina maritima for phytoremediation of metal polluted salt marshes: comparison of gram-positive and gram-negative strains.

    PubMed

    Paredes-Páliz, Karina I; Caviedes, Miguel A; Doukkali, Bouchra; Mateos-Naranjo, Enrique; Rodríguez-Llorente, Ignacio D; Pajuelo, Eloísa

    2016-10-01

    The aim of our work was the isolation and characterization of bacteria from the rhizosphere of Spartina maritima in the metal contaminated Odiel estuary (Huelva, SW Spain). From 25 strains, 84 % were identified as gram-positive, particularly Staphylococcus and Bacillus. Gram-negative bacteria were represented by Pantoea and Salmonella. Salt and heavy metal tolerance, metal bioabsorption, plant growth promoting (PGP) properties, and biofilm formation were investigated in the bacterial collection. Despite the higher abundance of gram-positive bacteria, gram-negative isolates displayed higher tolerance toward metal(loid)s (As, Cu, Zn, and Pb) and greater metal biosorption, as deduced from ICP-OES and SEM-EDX analyses. Besides, they exhibited better PGP properties, which were retained in the presence of metals and the ability to form biofilms. Gram-negative strains Pantoea agglomerans RSO6 and RSO7, together with gram-positive Bacillus aryabhattai RSO25, were selected for a bacterial consortium aimed to inoculate S. maritima plants in metal polluted estuaries for phytoremediation purposes.

  11. Cell lysis and DNA extraction of gram-positive and gram-negative bacteria from whole blood in a disposable microfluidic chip.

    PubMed

    Mahalanabis, Madhumita; Al-Muayad, Hussam; Kulinski, M Dominika; Altman, Dave; Klapperich, Catherine M

    2009-10-07

    Sepsis caused by gram positive and gram negative bacteria is the leading cause of death in noncoronary ICUs and the tenth leading cause of death in the United States. We have developed a microfluidic sample preparation platform for rapid on-chip detection of infectious organisms for point-of-care diagnostics. The microfluidic chips are made of a robust thermoplastic and can be easily multiplexed for high throughput applications. Bacteria are lysed on-chip via hybrid chemical/mechanical method. Once lysed, the bacterial DNA is isolated using a microscale silica bead/polymer composite solid-phase-extraction (SPE) column. Lysis was confirmed using off-chip real time PCR. We isolated and detected both gram-negative (Escherichia coli) and gram-positive (Bacillussubtilis and Enterococcus faecalis) bacterial genomic DNA from microliter scale spiked whole human blood samples. The system performs better for gram-negative bacteria than it does for gram-positive bacteria, with limits of detection at 10(2) CFU/ml and 10(3)-10(4) CFU/ml, respectively. Total extraction times are less than one hour and can be further decreased by altering the channel geometry and pumping configuration.

  12. Antimicrobial susceptibility among Gram-positive organisms collected from pediatric patients globally between 2004 and 2011: results from the Tigecycline Evaluation and Surveillance Trial.

    PubMed

    Brandon, Michael; Dowzicky, Michael J

    2013-07-01

    The Tigecycline Evaluation and Surveillance Trial (TEST) was designed to monitor global longitudinal changes in bacterial susceptibility to a panel of antimicrobial agents, including tigecycline. In this study, we examine susceptibility among Gram-positive isolates collected from pediatric patients globally between 2004 and 2011. A total of 9,422 Gram-positive isolates were contributed by 1,255 centers, predominantly from Europe and North America. One-third of Staphylococcus aureus isolates were methicillin resistant, peaking in prevalence in 2007. All S. aureus isolates (n = 3,614) were susceptible to linezolid, tigecycline, and vancomycin; minocycline, imipenem, and meropenem were also highly active (>92% susceptibility). Ampicillin and penicillin susceptibility increased significantly during the study period (P < 0.0001 for both). Streptococcus pneumoniae isolates (n = 3,373) were highly susceptible to vancomycin (100%), linezolid (>99%), and levofloxacin and tigecycline (both >96%); imipenem susceptibility was low (32%) in Africa while minocycline susceptibility was low in Asia-Pacific Rim (38%). Penicillin resistance occurred in one-fifth of all S. pneumoniae isolates, with penicillin susceptibility ranging from 14% in Africa to 65% in Europe. Streptococcus agalactiae isolates (n = 1,056) were highly susceptible to most antimicrobials, although only 16% were susceptible to minocycline. Enterococcus faecalis isolates (n = 1,112) were highly susceptible (>97%) to ampicillin, linezolid, penicillin, tigecycline, and vancomycin globally, but only 34% were minocycline susceptible; minocycline susceptibility decreased significantly from 2004 to 2011 (P < 0.001). Tigecycline and linezolid were highly active against Enterococcus faecium (n = 267) globally (100% and 98% susceptible, respectively). Tigecycline and linezolid were highly active against Gram-positive pathogens from pediatric patients in TEST 2004 to 2011, with vancomycin and the carbapenems performing well

  13. Identification of a d-Arabinose-5-Phosphate Isomerase in the Gram-Positive Clostridium tetani.

    PubMed

    Cech, David L; Markin, Katherine; Woodard, Ronald W

    2017-09-01

    d-Arabinose-5-phosphate (A5P) isomerases (APIs) catalyze the interconversion of d-ribulose-5-phosphate and d-arabinose-5-phosphate. Various Gram-negative bacteria, such as the uropathogenic Escherichia coli strain CFT073, contain multiple API paralogs (KdsD, GutQ, KpsF, and c3406) that have been assigned various cellular functions. The d-arabinose-5-phosphate formed by these enzymes seems to play important roles in the biosynthesis of lipopolysaccharide (LPS) and group 2 K-antigen capsules, as well as in the regulation of the cellular d-glucitol uptake and uropathogenic infectivity/virulence. The genome of a Gram-positive pathogenic bacterium, Clostridium tetani, contains a gene encoding a putative API, C. tetani API (CtAPI), even though C. tetani lacks both LPS and capsid biosynthetic genes. To better understand the physiological role of d-arabinose-5-phosphate in this Gram-positive organism, recombinant CtAPI was purified and characterized. CtAPI displays biochemical characteristics similar to those of APIs from Gram-negative organisms and complements the API deficiency of an E. coli API knockout strain. Thus, CtAPI represents the first d-arabinose-5-phosphate isomerase to be identified and characterized from a Gram-positive bacterium.IMPORTANCE The genome of Clostridium tetani, a pathogenic Gram-positive bacterium and the causative agent of tetanus, contains a gene (the CtAPI gene) that shares high sequence similarity with those of genes encoding d-arabinose-5-phosphate isomerases. APIs play an important role within Gram-negative bacteria in d-arabinose-5-phosphate production for lipopolysaccharide biosynthesis, capsule formation, and regulation of cellular d-glucitol uptake. The significance of our research is in identifying and characterizing CtAPI, the first Gram-positive API. Our findings show that CtAPI is specific to the interconversion of arabinose-5-phosphate and ribulose-5-phosphate while having no activity with the other sugars and sugar phosphates

  14. Multiplex Identification of Gram-Positive Bacteria and Resistance Determinants Directly from Positive Blood Culture Broths: Evaluation of an Automated Microarray-Based Nucleic Acid Test

    PubMed Central

    Buchan, Blake W.; Ginocchio, Christine C.; Manii, Ryhana; Cavagnolo, Robert; Pancholi, Preeti; Swyers, Lettie; Thomson, Richard B.; Anderson, Christopher; Kaul, Karen; Ledeboer, Nathan A.

    2013-01-01

    Background A multicenter study was conducted to evaluate the diagnostic accuracy (sensitivity and specificity) of the Verigene Gram-Positive Blood Culture Test (BC-GP) test to identify 12 Gram-positive bacterial gene targets and three genetic resistance determinants directly from positive blood culture broths containing Gram-positive bacteria. Methods and Findings 1,252 blood cultures containing Gram-positive bacteria were prospectively collected and tested at five clinical centers between April, 2011 and January, 2012. An additional 387 contrived blood cultures containing uncommon targets (e.g., Listeria spp., S. lugdunensis, vanB-positive Enterococci) were included to fully evaluate the performance of the BC-GP test. Sensitivity and specificity for the 12 specific genus or species targets identified by the BC-GP test ranged from 92.6%–100% and 95.4%–100%, respectively. Identification of the mecA gene in 599 cultures containing S. aureus or S. epidermidis was 98.6% sensitive and 94.3% specific compared to cefoxitin disk method. Identification of the vanA gene in 81 cultures containing Enterococcus faecium or E. faecalis was 100% sensitive and specific. Approximately 7.5% (87/1,157) of single-organism cultures contained Gram-positive bacteria not present on the BC-GP test panel. In 95 cultures containing multiple organisms the BC-GP test was in 71.6% (68/95) agreement with culture results. Retrospective analysis of 107 separate blood cultures demonstrated that identification of methicillin resistant S. aureus and vancomycin resistant Enterococcus spp. was completed an average of 41.8 to 42.4 h earlier using the BC-GP test compared to routine culture methods. The BC-GP test was unable to assign mecA to a specific organism in cultures containing more than one Staphylococcus isolate and does not identify common blood culture contaminants such as Micrococcus, Corynebacterium, and Bacillus. Conclusions The BC-GP test is a multiplex test capable of detecting most

  15. Development and evaluation of a selective and differential medium for the primary isolation of Peptostreptococcus micros.

    PubMed

    Turng, B F; Guthmiller, J M; Minah, G E; Falkler, W A

    1996-10-01

    Peptostreptococcus micros, an anaerobic gram-positive coccus, has been associated with periodontal and endodontic lesions, including those refractory to treatment, as well as many human polymicrobial infections in other body locations. A selective and differential medium for the primary isolation of P. micros was developed and evaluated. Columbia CNA agar, a selective medium for gram-positive cocci, was supplemented with glutathione and lead acetate (P. micros medium: PMM). P. micros has a characteristic of rapidly utilizing the reduced form of glutathione to form hydrogen sulfide, which reacts with lead acetate producing a black precipitate in the medium. When grown on PMM, P. micros can be easily identified by its typical colonial morphology and the presence of a black precipitate directly under the colony. PMM was compared for the growth of P. micros with phenylethyl alcohol agar (PEA) and Columbia base medium (CBM) with 80 strains of P. micros and 30 strains of other gram-positive cocci. All P. micros isolates tested grew and showed the typical morphology of P. micros on PMM. Using colony counts on CBM as controls, there was an average 81.8% recovery in the number of P. micros colonies on PMM, in contrast to an average 6.1% recovery on PEA. Subgingival plaque and tongue samples from 12 adult periodontitis and 6 early-onset periodontitis patients were cultured onto PMM for the isolation of P. micros. P. micros was isolated on PMM and identified biochemically and enzymatically from both adult periodontitis and early-onset periodontitis patients with higher percentages isolated from the diseased periodontal pockets of adult periodontitis patients; furthermore, this is the first isolation of P. micros from tongue samples taken from periodontally diseased patients. This medium in cultural studies will further our understanding and assist future investigations of P. micros involved in disease processes.

  16. Bacteraemia in neonatal foals: clinicopathological differences between Gram-positive and Gram-negative infections, and single organism and mixed infections.

    PubMed

    Corley, K T T; Pearce, G; Magdesian, K G; Wilson, W D

    2007-01-01

    Treatment for bacteraemia in foals must be started before the identity of the causative organism is known. Information aiding selection of effective antimicrobials should improve outcome. To describe differences in clinical and clinicopathological data and outcome in foals with bacteraemia due to different classes of bacteria. Records of foals with a positive blood culture, age < 10 days and presenting to a university hospital 1995-2004, were reviewed. Bacterial culture results, subject details, historical information, physical examination findings at admission and clinicopathological data generated during the first 48 h of hospitalisation were analysed. Results from foals with Gram-positive or Gram-negative organisms, single or mixed organism bacteraemias, and with bacteraemia due to 3 commonly isolated organisms were compared. Eighty-five foals met the inclusion criteria. Gram-negative organisms (n = 59) Gram-positive organisms (n = 13) or multiple organisms (n = 19) were cultured from individual foals. Foals with Gram-negative bacteraemia had lower total white blood cell and lymphocyte counts at admission than did those from which only Gram-positive bacteria were cultured. Mixed organism bacteraemia was associated with tachycardia, increased serum concentrations of sodium, chloride and urea nitrogen, acidosis, respiratory distress, recumbency on admission and nonsurvival. Actinobacillus spp. infections were associated with leucopenia, neutropenia, lymphopenia and depression on hospital admission. Recognising particular patterns of clinical and clinicopathological findings associated with infection with specific groups of bacteria may, in the future, aid antimicrobial selection and influence prognosis in bacteraemic foals.

  17. Effects of Ultraviolet Radiation on the Gram-positive marine bacterium Microbacterium maritypicum.

    PubMed

    Williams, Patrick D; Eichstadt, Shaundra L; Kokjohn, Tyler A; Martin, Eugene L

    2007-07-01

    Although extensive information is available on the effect ultraviolet (UV) radiation has on Gram-negative marine bacteria, there is a scarcity of data concerning UV radiation and Gram-positive marine bacteria. The focus of this paper is on Microbacterium maritypicum, with the Gram-negative Vibrio natriegens being used as a standard of comparison. M. maritypicum exhibited growth over a NaCl range of 0-1000 mM: , with optimum growth occurring between 0 and 400 mM: NaCl. In contrast, V. natriegens grew over a NaCl span of 250-1000 mM: , with best growth being observed between 250 and 600 mM: NaCl. UV radiation experiments were done using the medium with 250 mM: NaCl. For solar (UV-A and B) radiation and log-phase cells, M. maritypicum was determined to be three times more resistant than V. natriegens. For germicidal (UV-C) radiation, the pattern of resistance of the log-phase cells to the lethal effects of the radiation was even more pronounced, with the Gram-positive bacterium being more than 12 to 13 times more resistant. Similar data to the solar and germicidal log-phase UV kill curves were obtained for stationary-phase cells of both organisms. Photoreactivation was observed for both types of cells exposed to UV-C but none for cells treated with UV-A and B. When log phase cells of M.maritypicum were grown at 0.0 and 0.6 M: NaCl and exposed to UV-C radiation, no difference in survivorship patterns was noted from that of 0.25 M: NaCl grown cells. Although this study has only focused on two marine bacteria, our results indicate that the Gram-positive M. maritypicum could have a built-in advantage for survival in some marine ecosystems.

  18. Mechanical consequences of cell-wall turnover in the elongation of a Gram-positive bacterium.

    PubMed

    Misra, Gaurav; Rojas, Enrique R; Gopinathan, Ajay; Huang, Kerwyn Casey

    2013-06-04

    A common feature of walled organisms is their exposure to osmotic forces that challenge the mechanical integrity of cells while driving elongation. Most bacteria rely on their cell wall to bear osmotic stress and determine cell shape. Wall thickness can vary greatly among species, with Gram-positive bacteria having a thicker wall than Gram-negative bacteria. How wall dimensions and mechanical properties are regulated and how they affect growth have not yet been elucidated. To investigate the regulation of wall thickness in the rod-shaped Gram-positive bacterium Bacillus subtilis, we analyzed exponentially growing cells in different media. Using transmission electron and epifluorescence microscopy, we found that wall thickness and strain were maintained even between media that yielded a threefold change in growth rate. To probe mechanisms of elongation, we developed a biophysical model of the Gram-positive wall that balances the mechanical effects of synthesis of new material and removal of old material through hydrolysis. Our results suggest that cells can vary their growth rate without changing wall thickness or strain by maintaining a constant ratio of synthesis and hydrolysis rates. Our model also indicates that steady growth requires wall turnover on the same timescale as elongation, which can be driven primarily by hydrolysis rather than insertion. This perspective of turnover-driven elongation provides mechanistic insight into previous experiments involving mutants whose growth rate was accelerated by the addition of lysozyme or autolysin. Our approach provides a general framework for deconstructing shape maintenance in cells with thick walls by integrating wall mechanics with the kinetics and regulation of synthesis and turnover. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  19. Regulatory mechanisms differ in UMP kinases from gram-negative and gram-positive bacteria.

    PubMed

    Evrin, Cécile; Straut, Monica; Slavova-Azmanova, Neli; Bucurenci, Nadia; Onu, Adrian; Assairi, Liliane; Ionescu, Mihaela; Palibroda, Nicolae; Bârzu, Octavian; Gilles, Anne-Marie

    2007-03-09

    In this work, we examined the regulation by GTP and UTP of the UMP kinases from eight bacterial species. The enzyme from Gram-positive organisms exhibited cooperative kinetics with ATP as substrate. GTP decreased this cooperativity and increased the affinity for ATP. UTP had the opposite effect, as it decreased the enzyme affinity for ATP. The nucleotide analogs 5-bromo-UTP and 5-iodo-UTP were 5-10 times stronger inhibitors than the parent compound. On the other hand, UMP kinases from the Gram-negative organisms did not show cooperativity in substrate binding and catalysis. Activation by GTP resulted mainly from the reversal of inhibition caused by excess UMP, and inhibition by UTP was accompanied by a strong increase in the apparent K(m) for UMP. Altogether, these results indicate that, depending on the bacteria considered, GTP and UTP interact with different enzyme recognition sites. In Gram-positive bacteria, GTP and UTP bind to a single site or largely overlapping sites, shifting the T R equilibrium to either the R or T form, a scenario corresponding to almost all regulatory proteins, commonly called K systems. In Gram-negative organisms, the GTP-binding site corresponds to the unique allosteric site of the Gram-positive bacteria. In contrast, UTP interacts cooperatively with a site that overlaps the catalytic center, i.e. the UMP-binding site and part of the ATP-binding site. These characteristics make UTP an original regulator of UMP kinases from Gram-negative organisms, beyond the common scheme of allosteric control.

  20. Glycerol monolaurate inhibits the effects of Gram-positive select agents on eukaryotic cells.

    PubMed

    Peterson, Marnie L; Schlievert, Patrick M

    2006-02-21

    Many exotoxins of Gram-positive bacteria, such as superantigens [staphylococcal enterotoxins, toxic shock syndrome toxin-1 (TSST-1), and streptococcal pyrogenic exotoxins] and anthrax toxin are bioterrorism agents that cause diseases by immunostimulation or cytotoxicity. Glycerol monolaurate (GML), a fatty acid monoester found naturally in humans, has been reported to prevent synthesis of Gram-positive bacterial exotoxins. This study explored the ability of GML to inhibit the effects of exotoxins on mammalian cells and prevent rabbit lethality from TSS. GML (>or=10 microg/mL) inhibited superantigen (5 microg/mL) immunoproliferation, as determined by inhibition of (3)H-thymidine incorporation into DNA of human peripheral blood mononuclear cells (1 x 10(6) cells/mL) as well as phospholipase Cgamma1, suggesting inhibition of signal transduction. The compound (20 microg/mL) prevented superantigen (100 microg/mL) induced cytokine secretion by human vaginal epithelial cells (HVECs) as measured by ELISA. GML (250 microg) inhibited rabbit lethality as a result of TSST-1 administered vaginally. GML (10 microg/mL) inhibited HVEC and macrophage cytotoxicity by anthrax toxin, prevented erythrocyte lysis by purified hemolysins (staphylococcal alpha and beta) and culture fluids containing streptococcal and Bacillus anthracis hemolysins, and was nontoxic to mammalian cells (up to 100 microg/mL) and rabbits (250 microg). GML stabilized mammalian cell membranes, because erythrocyte lysis was reduced in the presence of hypotonic aqueous solutions (0-0.05 M saline) or staphylococcal alpha- and beta-hemolysins when erythrocytes were pretreated with GML. GML may be useful in the management of Gram-positive exotoxin illnesses; its action appears to be membrane stabilization with inhibition of signal transduction.

  1. Desulfotomaculum spp. and related gram-positive sulfate-reducing bacteria in deep subsurface environments

    PubMed Central

    Aüllo, Thomas; Ranchou-Peyruse, Anthony; Ollivier, Bernard; Magot, Michel

    2013-01-01

    Gram-positive spore-forming sulfate reducers and particularly members of the genus Desulfotomaculum are commonly found in the subsurface biosphere by culture based and molecular approaches. Due to their metabolic versatility and their ability to persist as endospores. Desulfotomaculum spp. are well-adapted for colonizing environments through a slow sedimentation process. Because of their ability to grow autotrophically (H2/CO2) and produce sulfide or acetate, these microorganisms may play key roles in deep lithoautotrophic microbial communities. Available data about Desulfotomaculum spp. and related species from studies carried out from deep freshwater lakes, marine sediments, oligotrophic and organic rich deep geological settings are discussed in this review. PMID:24348471

  2. Expression systems for industrial Gram-positive bacteria with low guanine and cytosine content.

    PubMed

    de Vos, W M; Kleerebezem, M; Kuipers, O P

    1997-10-01

    Recent years have seen an increase in the development of gene expression systems for industrial Gram-positive bacteria with low guanine and cytosine content that belong to the genera Bacillus, Clostridium, Lactococcus, Lactobacillus, Staphylococcus and Streptococcus. In particular, considerable advances have been made in the construction of inducible gene expression systems based on the capacity of these bacteria to utilize specific sugars or to secrete autoinducing peptides that are involved in quorum sensing. These controlled expression systems allow for present and future exploitation of these bacteria as cell factories in medical, agricultural, and food biotechnology.

  3. Telavancin versus Vancomycin for Hospital-Acquired Pneumonia due to Gram-positive Pathogens

    PubMed Central

    Lalani, Tahaniyat; Corey, G. Ralph; Kanafani, Zeina A.; Nannini, Esteban C.; Rocha, Marcelo G.; Rahav, Galia; Niederman, Michael S.; Kollef, Marin H.; Shorr, Andrew F.; Lee, Patrick C.; Lentnek, Arnold L.; Luna, Carlos M.; Fagon, Jean-Yves; Torres, Antoni; Kitt, Michael M.; Genter, Fredric C.; Barriere, Steven L.; Friedland, H. David; Stryjewski, Martin E.

    2011-01-01

    Background. Telavancin is a lipoglycopeptide bactericidal against gram-positive pathogens. Methods. Two methodologically identical, double-blind studies (0015 and 0019) were conducted involving patients with hospital-acquired pneumonia (HAP) due to gram-positive pathogens, particularly methicillin-resistant Staphylococcus aureus (MRSA). Patients were randomized 1:1 to telavancin (10 mg/kg every 24 h) or vancomycin (1 g every 12 h) for 7–21 days. The primary end point was clinical response at follow-up/test-of-cure visit. Results. A total of 1503 patients were randomized and received study medication (the all-treated population). In the pooled all-treated population, cure rates with telavancin versus vancomycin were 58.9% versus 59.5% (95% confidence interval [CI] for the difference, –5.6% to 4.3%). In the pooled clinically evaluable population (n = 654), cure rates were 82.4% with telavancin and 80.7% with vancomycin (95% CI for the difference, –4.3% to 7.7%). Treatment with telavancin achieved higher cure rates in patients with monomicrobial S. aureus infection and comparable cure rates in patients with MRSA infection; in patients with mixed gram-positive/gram-negative infections, cure rates were higher in the vancomycin group. Incidence and types of adverse events were comparable between the treatment groups. Mortality rates for telavancin-treated versus vancomycin-treated patients were 21.5% versus 16.6% (95% CI for the difference, –0.7% to 10.6%) for study 0015 and 18.5% versus 20.6% (95% CI for the difference, –7.8% to 3.5%) for study 0019. Increases in serum creatinine level were more common in the telavancin group (16% vs 10%). Conclusions. The primary end point of the studies was met, indicating that telavancin is noninferior to vancomycin on the basis of clinical response in the treatment of HAP due to gram-positive pathogens. PMID:21148517

  4. The Role of Functional Amyloids in Multicellular Growth and Development of Gram-Positive Bacteria.

    PubMed

    Dragoš, Anna; Kovács, Ákos T; Claessen, Dennis

    2017-08-07

    Amyloid fibrils play pivotal roles in all domains of life. In bacteria, these fibrillar structures are often part of an extracellular matrix that surrounds the producing organism and thereby provides protection to harsh environmental conditions. Here, we discuss the role of amyloid fibrils in the two distant Gram-positive bacteria, Streptomyces coelicolor and Bacillus subtilis. We describe how amyloid fibrils contribute to a multitude of developmental processes in each of these systems, including multicellular growth and community development. Despite this variety of tasks, we know surprisingly little about how their assembly is organized to fulfill all these roles.

  5. New Gram-Positive Agents: the Next Generation of Oxazolidinones and Lipoglycopeptides

    PubMed Central

    Crotty, Matthew P.; Krekel, Tamara

    2016-01-01

    The growing problem of antimicrobial resistance among bacterial pathogens, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), has reached a critical state. Tedizolid phosphate, dalbavancin, and oritavancin have recently been approved by the U.S. Food and Drug Administration (FDA) for the treatment of acute bacterial skin and skin structure infections (ABSSSI) and represent the next generation of oxazolidinones and lipoglycopeptides. All three agents exhibit in vitro activity and clinical efficacy against MRSA. Tedizolid phosphate and oritavancin demonstrate in vitro activity against VRE. These new Gram-positive agents are reviewed here. PMID:26962092

  6. New and improved? A review of novel antibiotics for Gram-positive bacteria.

    PubMed

    Abbas, M; Paul, M; Huttner, A

    2017-10-01

    The number of antibiotics in the pipeline targeting Gram-positive pathogens has increased in recent years. This narrative review aims to provide a summary of existing evidence on efficacy, microbiological spectrum and safety of novel systemic antibiotics that have either recently been licensed or completed phase III trials, and possess activity predominantly against Gram-positive organisms. A review of the published literature via the MEDLINE database was performed. In addition, ongoing trials were identified through a search of the clinical trial registration platform clinicaltrials.gov, and when necessary, pharmaceutical companies responsible for the development of the drug were contacted for further information. Data on development, microbiological spectrum, pharmacokinetic/pharmacodynamic properties, clinical efficacy, safety and cost are presented for the new cephalosporins ceftaroline and ceftobiprole; the lipoglycopeptides dalbavancin, oritavancin and telavancin; the fluoroquinolones delafloxacin, nemonoxacin and zabofloxacin; the dihydrofolate-reductase inhibitor iclaprim; the pleuromutilin lefamulin; and the tetracycline omadacycline. Although promising, these new antibiotics have so far been tested in non-severe infections whose treatment is generally uncomplicated and whose aetiologies were not predominantly multidrug-resistant pathogens. None of the new antibiotics have shown superiority to standard care, and none have been investigated for patient-relevant outcomes. Safety and pharmacokinetic data continue to be lacking. How these new drugs are to be integrated into the current armamentarium remains to be established. Copyright © 2017 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  7. Peptidoglycan architecture of Gram-positive bacteria by solid-state NMR.

    PubMed

    Kim, Sung Joon; Chang, James; Singh, Manmilan

    2015-01-01

    Peptidoglycan is an essential component of cell wall in Gram-positive bacteria with unknown architecture. In this review, we summarize solid-state NMR approaches to address some of the unknowns in the Gram-positive bacteria peptidoglycan architecture: 1) peptidoglycan backbone conformation, 2) PG-lattice structure, 3) variations in the peptidoglycan architecture and composition, 4) the effects of peptidoglycan bridge-length on the peptidoglycan architecture in Fem mutants, 5) the orientation of glycan strands with respect to the membrane, and 6) the relationship between the peptidoglycan structure and the glycopeptide antibiotic mode of action. Solid-state NMR analyses of Staphylococcus aureus cell wall show that peptidoglycan chains are surprisingly ordered and densely packed. The peptidoglycan disaccharide backbone adopts 4-fold screw helical symmetry with the disaccharide unit periodicity of 40Å. Peptidoglycan lattice in the S. aureus cell wall is formed by cross-linked PG stems that have parallel orientations. The structural characterization of Fem-mutants of S. aureus with varying lengths of bridge structures suggests that the PG-bridge length is an important determining factor for the PG architecture.

  8. Visualizing the production and arrangement of peptidoglycan in Gram-positive cells.

    PubMed

    Popham, David L

    2013-05-01

    Decades of study have revealed the fine chemical structure of the bacterial peptidoglycan cell wall, but the arrangement of the peptidoglycan strands within the wall has been challenging to define. The application of electron cryotomography (ECT) and new methods for fluorescent labelling of peptidoglycan are allowing new insights into wall structure and synthesis. Two articles in this issue examine peptidoglycan structures in the model Gram-positive species Bacillus subtilis. Beeby et al. combined visualization of peptidoglycan using ECT with molecular modelling of three proposed arrangements of peptidoglycan strands to identify the model most consistent with their data. They argue convincingly for a Gram-positive wall containing multiple layers of peptidoglycan strands arranged circumferentially around the long axis of the rod-shaped cell, an arrangement similar to the single layer of peptidoglycan in similarly shaped Gram-negative cells. Tocheva et al. examined sporulating cells using ECT and fluorescence microscopy to demonstrate the continuous production of a thin layer of peptidoglycan around the developing spore as it is engulfed by the membrane of the adjacent mother cell. The presence of this peptidoglycan in the intermembrane space allows the refinement of a model for engulfment, which has been known to include peptidoglycan synthetic and lytic functions.

  9. Interfacial charge transfer between CdTe quantum dots and Gram negative vs. Gram positive bacteria.

    SciTech Connect

    Dumas, E.; Gao, C.; Suffern, D.; Bradforth, S. E.; Dimitrejevic, N. M.; Nadeau, J. L.; McGill Univ.; Univ. of Southern California

    2010-01-01

    Oxidative toxicity of semiconductor and metal nanomaterials to cells has been well established. However, it may result from many different mechanisms, some requiring direct cell contact and others resulting from the diffusion of reactive species in solution. Published results are contradictory due to differences in particle preparation, bacterial strain, and experimental conditions. It has been recently found that C{sub 60} nanoparticles can cause direct oxidative damage to bacterial proteins and membranes, including causing a loss of cell membrane potential (depolarization). However, this did not correlate with toxicity. In this study we perform a similar analysis using fluorescent CdTe quantum dots, adapting our tools to make use of the particles fluorescence. We find that two Gram positive strains show direct electron transfer to CdTe, resulting in changes in CdTe fluorescence lifetimes. These two strains also show changes in membrane potential upon nanoparticle binding. Two Gram negative strains do not show these effects - nevertheless, they are over 10-fold more sensitive to CdTe than the Gram positives. We find subtoxic levels of Cd{sup 2+} release from the particles upon irradiation of the particles, but significant production of hydroxyl radicals, suggesting that the latter is a major source of toxicity. These results help establish mechanisms of toxicity and also provide caveats for use of certain reporter dyes with fluorescent nanoparticles which will be of use to anyone performing these assays. The findings also suggest future avenues of inquiry into electron transfer processes between nanomaterials and bacteria.

  10. Fumaric Acid and Slightly Acidic Electrolyzed Water Inactivate Gram Positive and Gram Negative Foodborne Pathogens

    PubMed Central

    Tango, Charles Nkufi; Mansur, Ahmad Rois; Oh, Deog-Hwan

    2015-01-01

    Sanitizing effectiveness of slightly acidic electrolyzed water (SAEW) and fumaric acid (FA) at different dipping temperatures (25–60 °C), times (1–5 min), and concentrations (5–30 ppm for SAEW and 0.125%–0.5% for FA) on pure cultures of two Gram positive pathogens Staphylococcus aureus (SA) and Listeria monocytogenes (LM) and two Gram negative pathogens Escherichia coli O157:H7 (EC) and Salmonella Typhimurium (ST) was evaluated. FA (0.25%) showed the strongest sanitizing effect, demonstrating complete inactivation of EC, ST, and LM, while SA was reduced by 3.95–5.76 log CFU/mL at 25–60 °C, respectively, after 1 min of treatment. For SAEW, the complete inactivation was obtained when available chlorine concentration was increased to 20 ppm at 40 °C for 3 and 5 min. Moreover, Gram positive pathogens have been shown to resist to all treatment trends more than Gram negative pathogens throughout this experiment. Regardless of the different dipping temperatures, concentrations, and times, FA treatment was more effective than treatment with SAEW for reduction of foodborne pathogens. This study demonstrated that application of FA in food systems may be useful as a method for inactivation of foodborne pathogens. PMID:27682077

  11. Organic solvent adaptation of Gram positive bacteria: applications and biotechnological potentials.

    PubMed

    Torres, Sebastian; Pandey, Ashok; Castro, Guillermo R

    2011-01-01

    Organic-solvent-tolerant bacteria are considered extremophiles with different tolerance levels that change among species and strains, but also depend on the inherent toxicity of the solvent. Extensive studies to understand the mechanisms of organic solvent tolerance have been done in Gram-negative bacteria. On the contrary, the information on the solvent tolerance mechanisms in Gram-positive bacteria remains scarce. Possible shared mechanisms among Gram-(-) and Gram-(+) microorganisms include: energy-dependent active efflux pumps that export toxic organic solvents to the external medium; cis-to-trans isomerization of unsaturated membrane fatty acids and modifications in the membrane phospholipid headgroups; formation of vesicles loaded with toxic compounds; and changes in the biosynthesis rate of phospholipids to accelerate repair processes. However, additional physiological responses of Gram-(+) bacteria to organic solvents seem to be specific. The aim of the present work is to review the state of the art of responsible mechanisms for organic solvent tolerance in Gram-positive bacteria, and their industrial and environmental biotechnology potential.

  12. Effect of disinfection on number and stainability of gram-positive bacteria.

    PubMed

    van Mullem, P J; Wijnbergen, M

    1989-11-01

    Evidence provided by the Brown and Brenn stain for the presence of bacteria in fixed tissue sections depends on the ability to demonstrate them by staining. Previously, in a model experiment, it has been shown that demineralizing agents reduce the number of blue-staining Gram-positive bacteria (Wijnbergen & Van Mullem 1987). In the present study the influence of a structure-destroying disinfectant, a structure-preserving disinfectant or heat disinfection on number and stainability was investigated using S. faecalis suspensions. Numbers were determined using a haemocytometer, and percentages of blue-staining organisms were ascertained from smears. Immediately after disinfection the relative number of Gram-positive staining bacteria was reduced by a factor of three for chlorhexidine, almost two for alcoformol, and was slightly reduced by heat. After 4 days of storage the reduction factors were 90, 4, and 2, respectively. After 14 days of storage the reduction factors were infinite, 30 and 5, respectively. These results were explained on the basis of the rate of cell wall destruction evoked by the respective agents.

  13. Identification of gram-negative and gram-positive bacteria by fluorescence studies

    NASA Astrophysics Data System (ADS)

    Demchak, Jonathan; Calabrese, Joseph; Tzolov, Marian

    2011-03-01

    Several type strains of bacteria including Vibrio fischeri, Azotobacter vinelandii, Enterobacter cloacae, and Corynebacterium xerosis, were cultured in the laboratory following standard diagnostic protocol based on their individual metabolic strategies. The bacterial cultures were not further treated and they were studied in their pristine state (pure culture - axenic). The fluorescent studies were applied using a continuous wave and a pulsed excitation light sources. Emission and excitation spectra were recorded for the continuous wave excitation and they all show similar spectral features with the exception of the gram positive bacteria showing vibronic structures. The vibrational modes involved in these vibronic bands have energy typical for carbon-carbon vibrations. The fluorescence is quenched in addition of water, even a very thin layer, which confirms that the observed spectral features originate from the outer parts of the bacteria. These results allow to conclude that the fluorescence spectroscopy can be used as a method for studying the membranes of the bacteria and eventually to discriminate between gram positive and gram negative bacteria. The pulsed experiments show that the fluorescence lifetime is in the sub-microsecond range. The results indicate that the observed spectra are superposition of the emission with different lifetimes.

  14. METABOLIC PROPERTIES OF SOME L FORMS DERIVED FROM GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA.

    PubMed

    WEIBULL, C; GYLLANG, H

    1965-06-01

    Weibull Claes (Central Bacteriological Laboratory of Stockholm City, Stockholm, Sweden), and Hans Gyllang. Metabolic properties of some L forms derived from gram-positive and gram-negative bacteria. J. Bacteriol. 89:1443-1447. 1965.-L forms of two gram-positive bacteria, a staphylococcus and a diphtheroid, were found to be devoid of catalase and cytochromes, whereas the normal bacteria from which these L forms were derived contained large amounts of these enzymes. On the other hand, L forms of a gram-negative bacterium, Proteus mirabilis, contained the same cytochromes as normal Proteus bacteria. (Previous investigations showed that normal cells and L forms of P. mirabilis contain approximately the same amounts of catalase.) The respiratory quotients (Q(O2)) of all L forms studied were much lower than those of the corresponding normal bacteria. The conversion of the normal organisms into L forms did not markedly affect their growth rate, measured as the time required for doubling the bacterial mass during the exponential-growth phase.

  15. Synthetic Quorum Sensing and Cell-Cell Communication in Gram-Positive Bacillus megaterium.

    PubMed

    Marchand, Nicholas; Collins, Cynthia H

    2016-07-15

    The components of natural quorum-sensing (QS) systems can be used to engineer synthetic communication systems that regulate gene expression in response to chemical signals. We have used the machinery from the peptide-based agr QS system from Staphylococcus aureus to engineer a synthetic QS system in Bacillus megaterium to enable autoinduction of a target gene at high cell densities. Growth and gene expression from these synthetic QS cells were characterized in both complex and minimal media. We also split the signal production and sensing components between two strains of B. megaterium to produce sender and receiver cells and characterized the resulting communication in liquid media and on semisolid agar. The system described in this work represents the first synthetic QS and cell-cell communication system that has been engineered to function in a Gram-positive host, and it has the potential to enable the generation of dynamic gene regulatory networks in B. megaterium and other Gram-positive organisms.

  16. A CYTOCHEMICAL LOCALIZATION OF REDUCTIVE SITES IN A GRAM-POSITIVE BACTERIUM

    PubMed Central

    van Iterson, Woutera; Leene, W.

    1964-01-01

    In bacteria the exact location of a respiratory enzyme system comparable to that of the mitochondria of other cells has remained uncertain. On the one hand, the existence of particulate "bacterial mitochondria" has been advocated (Mudd); on the other hand, important enzymes of the respiratory chain were recovered in the cytoplasmic membranes associated with some granular material (Weibull). In order to gain insight into this question, sites of reducing activity were localized in thin sections of bacteria using the reduction of potassium tellurite as an indicator. When this salt was added to the culture medium of Bacillus subtilis, it turned out that in this Gram-positive organism the reduced product is strictly bound at two sites, and that the plasma membrane does not materially gain in electron opacity through deposition of the reduced product. The reduction product is found on or in the membranes of particular organelles, which may possibly be regarded as the mitochondrial equivalents in Gram-positive bacteria, and which are sometimes seen connected to the plasma membrane. The second location is in thin rod-like elements at the cell periphery, possibly the sites from which the flagella emerge. PMID:14128042

  17. Fumaric Acid and Slightly Acidic Electrolyzed Water Inactivate Gram Positive and Gram Negative Foodborne Pathogens.

    PubMed

    Tango, Charles Nkufi; Mansur, Ahmad Rois; Oh, Deog-Hwan

    2015-02-12

    Sanitizing effectiveness of slightly acidic electrolyzed water (SAEW) and fumaric acid (FA) at different dipping temperatures (25-60 °C), times (1-5 min), and concentrations (5-30 ppm for SAEW and 0.125%-0.5% for FA) on pure cultures of two Gram positive pathogens Staphylococcus aureus (SA) and Listeria monocytogenes (LM) and two Gram negative pathogens Escherichia coli O157:H7 (EC) and Salmonella Typhimurium (ST) was evaluated. FA (0.25%) showed the strongest sanitizing effect, demonstrating complete inactivation of EC, ST, and LM, while SA was reduced by 3.95-5.76 log CFU/mL at 25-60 °C, respectively, after 1 min of treatment. For SAEW, the complete inactivation was obtained when available chlorine concentration was increased to 20 ppm at 40 °C for 3 and 5 min. Moreover, Gram positive pathogens have been shown to resist to all treatment trends more than Gram negative pathogens throughout this experiment. Regardless of the different dipping temperatures, concentrations, and times, FA treatment was more effective than treatment with SAEW for reduction of foodborne pathogens. This study demonstrated that application of FA in food systems may be useful as a method for inactivation of foodborne pathogens.

  18. Cyclodepsipeptides produced by actinomycetes inhibit cyclic-peptide-mediated quorum sensing in Gram-positive bacteria.

    PubMed

    Desouky, Said E; Shojima, Akane; Singh, Ravindra Pal; Matsufuji, Takahisa; Igarashi, Yasuhiro; Suzuki, Takashi; Yamagaki, Tohru; Okubo, Ken-Ichi; Ohtani, Kaori; Sonomoto, Kenji; Nakayama, Jiro

    2015-07-01

    Cyclic peptides are commonly used as quorum-sensing autoinducers in Gram-positive Firmicutes bacteria. Well-studied examples of such molecules are thiolactone and lactone, used to regulate the expression of a series of virulence genes in the agr system of Staphylococcus aureus and the fsr system of Enterococcus faecalis, respectively. Three cyclodepsipeptides WS9326A, WS9326B and cochinmicin II/III were identified as a result of screening actinomycetes culture extracts for activity against the agr/fsr system. These molecules are already known as receptor antagonists, the first two for tachykinin and the last one for endothelin. WS9326A also inhibited the transcription of pfoA regulated by the VirSR two-component system in Clostridium perfringens. Receptor-binding assays using a fluorescence-labeled autoinducer (FITC-GBAP) showed that WS9326A and WS9326B act as receptor antagonists in this system. In addition, an ex vivo assay showed that WS9326B substantially attenuated the toxicity of S. aureus for human corneal epithelial cells. These results suggest that these three natural cyclodepsipeptides have therapeutic potential for targeting the cyclic peptide-mediated quorum sensing of Gram-positive pathogens. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  19. Cell to cell communication by autoinducing peptides in gram-positive bacteria.

    PubMed

    Sturme, Mark H J; Kleerebezem, Michiel; Nakayama, Jiro; Akkermans, Antoon D L; Vaugha, Elaine E; de Vos, Willem M

    2002-08-01

    While intercellular communication systems in Gram-negative bacteria are often based on homoserine lactones as signalling molecules, it has been shown that autoinducing peptides are involved in intercellular communication in Gram-positive bacteria. Many of these peptides are exported by dedicated systems, posttranslationally modified in various ways, and finally sensed by other cells via membrane-located receptors that are part of two-component regulatory systems. In this way the expression of a variety of functions including virulence, genetic competence and the production of antimicrobial compounds can be modulated in a co-ordinated and cell density- and growth phase-dependent manner. Occasionally the autoinducing peptide has a dual function, such as in the case of nisin that is both a signalling pheromone involved in quorum sensing and an antimicrobial peptide. Moreover, biochemical, genetic and genomic studies have shown that bacteria may contain multiple quorum sensing systems, underlining the importance of intercellular communication. Finally, in some cases different peptides may be recognised by the same receptor, while also hybrid receptors have been constructed that respond to new peptides or show novel responses. This paper provides an overview of the characteristics of autoinducing peptide-based quorum sensing systems, their application in various gram-positive bacteria, and the discovery of new systems in natural and engineered ecosystems.

  20. Genetic and Structural Analyses of RRNPP Intercellular Peptide Signaling of Gram-Positive Bacteria.

    PubMed

    Neiditch, Matthew B; Capodagli, Glenn C; Prehna, Gerd; Federle, Michael J

    2017-09-06

    Bacteria use diffusible chemical messengers, termed pheromones, to coordinate gene expression and behavior among cells in a community by a process known as quorum sensing. Pheromones of many gram-positive bac, such as Bacillus and Streptococcus, are small, linear peptides secreted from cells and subsequently detected by sensory receptors such as those belonging to the large family ofRRNPP proteins. These proteins are cytoplasmic pheromone receptors sharing a structurally similar pheromone-binding domain that functions allosterically to regulate receptor activity. X-ray crystal structures of prototypical RRNPP members have provided atomic-level insights into their mechanism and regulation by pheromones. This review provides an overview of RRNPP prototype signaling; describes the structure-function of this protein family, which is spread widely among gram-positive bacteria; and suggests approaches to target RRNPP systems in order to manipulate beneficial and harmful bacterial behaviors. Expected final online publication date for the Annual Review of Genetics Volume 51 is November 23, 2017. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  1. Antibacterial activity and mechanism of action of tick defensin against Gram-positive bacteria.

    PubMed

    Nakajima, Yoshiro; Ishibashi, Jun; Yukuhiro, Fumiko; Asaoka, Ai; Taylor, DeMar; Yamakawa, Minoru

    2003-12-05

    Defensins are a major group of antimicrobial peptides and are found widely in vertebrates, invertebrates and plants. Invertebrate defensins have been identified from insects, scorpions, mussels and ticks. In this study, chemically synthesized tick defensin was used to further investigate the activity spectrum and mode of action of natural tick defensin. Synthetic tick defensin showed antibacterial activity against many Gram-positive bacteria but not Gram-negative bacteria and low hemolytic activity, characteristic of invertebrate defensins. Furthermore, bactericidal activity against pathogenic Gram-positive bacteria including Bacillus cereus, Enterococcus faecalis and methicillin-resistant Staphylococcus aureus was observed. However, more than 30 min was necessary for tick defensin to completely kill bacteria. The interaction of tick defensin with the bacterial cytoplasmic membrane and its ability to disrupt the membrane potential was analyzed. Tick defensin was able to disrupt the membrane potential over a period of 30-60 min consistent with its relatively slow killing. Transmission electron microscopy of Micrococcus luteus treated with tick defensin showed lysis of the cytoplasmic membrane and leakage of cellular cytoplasmic contents. These findings suggest that the primary mechanism of action of tick defensin is bacterial cytoplasmic membrane lysis. In addition, incomplete cell division with multiple cross-wall formation was occasionally seen in tick defensin-treated bacteria showing pleiotropic secondary effects of tick defensin.

  2. Clinical evaluation of moxalactam: evidence of decreased efficacy in gram-positive aerobic infections.

    PubMed Central

    Salzer, W; Pegram, P S; McCall, C E

    1983-01-01

    Moxalactam was used as initial, empirical therapy in 69 patients with a variety of serious bacterial infections, 32% of which were accompanied by bacteremia. Overall, the success rate was 83% and drug-related adverse effects were minimal. The drug was less efficacious in infections caused by aerobic gram-positive pathogens than it was in those caused by gram-negative pathogens. The following gram-positive organisms were associated with special problems during moxalactam therapy: Streptococcus pneumoniae (development of meningitis and a relapse of pneumonia with a more resistant strain), Staphylococcus epidermidis (in vivo emergence of moxalactam resistance, and the enterococci (failure of therapy and a fatal superinfection. Moxalactam performed well in infections caused by most gram-negative organisms, including aminoglycoside-resistant strains, but the previously reported emergence of gram-negative bacillary resistance to moxalactam during therapy was reconfirmed in our series with Serratia marcescens. The use of moxalactam in the treatment of gram-negative meningitis was further supported by a patient with meningitis-ventriculitis caused by Bacteroides fragilis who was cured with moxalactam after failure on chloramphenicol. PMID:6222696

  3. Recently approved and investigational antibiotics for treatment of severe infections caused by Gram-positive bacteria.

    PubMed

    Appelbaum, Peter C; Jacobs, Michael R

    2005-10-01

    The development of resistance in the major pathogenic Gram-positive genera Staphylococcus and Streptococccus has led to the need for new agents that are able to overcome existing resistance mechanisms or that have novel mechanisms of action. There is currently a dearth of new agents that are active against resistant bacterial species. Agents that have recently been approved for clinical use include linezolid, the first oxazolidinone in clinical use, daptomycin, the first lipopeptide in clinical use, and telithromycin, a ketolide that is derived from clarithromycin. Agents currently in clinical development include tigecycline, a broad-spectrum intravenous tetracycline, ceftobiprole, a broad-spectrum cephalosporin that has activity against methicillin-resistant staphylococci, DX-619 and WCK-771, which are potent quinolones that have activity against quinolone-resistant staphylococci, oritavancin and dalbavancin, both of which are new glycopeptides, and iclaprim, which is a diaminopyrimidine. Additional agents that are in preclinical development against Gram-positive pathogens include quinoline-naphthyridine agents, which target novel DNA gyrase sites, other novel quinolones that have high potency, peptide deformylase inhibitors, and new lincosamide, oxazolidinone, lipopeptide and cephalosporin derivatives. Misuse of potent new agents will, however, result in the inevitable development of resistance to these agents; responsible use of potent new agents is required to prevent continuation of this vicious cycle.

  4. Gram-positive resistance: challenge for the development of new antibiotics.

    PubMed

    Baquero, F

    1997-05-01

    The incidence of infections caused by multidrug-resistant Gram-positive organisms is increasing despite advances in antibacterial therapy over the last 20 years. As the pathogens causing these infections are frequently resistant to most currently available antibacterials, they are extremely difficult to treat. Problematic pathogens include strains of Streptococcus pneumoniae resistant to beta-lactams and macrolides, viridans group streptococci resistant to beta-lactams and aminoglycosides, enterococci resistant to vancomycin and teicoplanin and highly resistant to penicillins and aminoglycosides, and Staphylococcus aureus resistant to methicillin, other beta-lactams, macrolides, lincosamides and aminoglycosides. Other important pathogens include Streptococcus pyogenes resistant to macrolides (and suspected to be resistant to penicillin), macrolide-resistant streptococci of groups B, C, and G, coagulase-negative staphylococci resistant to beta-lactams, aminoglycosides, macrolides, lincosamides and glycopeptides, multiresistant strains of Listeria and Corynebacterium and Gram-positive anaerobes, such as Peptostreptococcus and Clostridium, resistant to penicillins and macrolides. Thus, there is an urgent need for new antibacterial agents that are able to overcome multidrug-resistant mechanisms. The novel semisynthetic injectable streptogramin quinupristin/dalfopristin offers the prospect of effective treatment against many of the above pathogens.

  5. Fluorescence studies of gram-positive and gram-negative bacteria

    NASA Astrophysics Data System (ADS)

    Blust, Brittni

    2012-02-01

    Autofluorescence is a relatively unexplored technique for identification. It is nondestructive, noncontact, fast, and has the potential to be integrated in small handheld devices. On the other hand, the autofluorescent signal is sometimes very week, or it can be overwhelmed by the emission of a surrounding medium. We are exploring the possibility to develop an optical method for identification of the Gram-type of bacterial cultures based on the autofluorescence. We have enhanced the detectivity of a standard fluorimeter using combination of bandpass and long pass filters. In this particular study, we are investigating if the previously observed difference in the autofluorescent spectra of Gram-positive and Gram-negative bacteria is dependent on the age of the culture. We have selected two types of bacteria, Kocuria rhizophila and Alcagenes faecalis, and we have monitored in equal time intervals of their development the autofluorescence spectra. The stages of development were monitored separately by measuring the turbidity and creating a growth curve. The goal of this study is to find out if the previously observed difference in the autofluorescence spectra of Gram-positive and Gram-negative bacteria is dependent on the stage of the development of the bacterial culture.

  6. Symmetrically Substituted Xanthone Amphiphiles Combat Gram-Positive Bacterial Resistance with Enhanced Membrane Selectivity.

    PubMed

    Lin, Shuimu; Koh, Jun-Jie; Aung, Thet Tun; Lim, Fanghui; Li, Jianguo; Zou, Hanxun; Wang, Lin; Lakshminarayanan, Rajamani; Verma, Chandra; Wang, Yingjun; Tan, Donald T H; Cao, Derong; Beuerman, Roger W; Ren, Li; Liu, Shouping

    2017-02-23

    This is the first report of the design of a new series of symmetric xanthone derivatives that mimic antimicrobial peptides using a total synthesis approach. This novel design is advantageous because of its low cost, synthetic simplicity and versatility, and easy tuning of amphiphilicity by controlling the incorporated cationic and hydrophobic moieties. Two water-soluble optimized compounds, 6 and 18, showed potent activities against Gram-positive bacteria, including MRSA and VRE (MICs = 0.78-6.25 μg/mL) with a rapid bactericidal effect, low toxicity, and no emergence of drug resistance. Both compounds demonstrated enhanced membrane selectivity that was higher than those of most membrane-active antimicrobials in clinical trials or previous reports. The compounds appear to kill bacteria by disrupting their membranes. Significantly, 6 was effective in vivo using a mouse model of corneal infection. These results provide compelling evidence that these compounds have therapeutic potential as novel antimicrobials for multidrug-resistant Gram-positive infections.

  7. Antimicrobial resistance pattern of Gram-positive bacteria during three consecutive years at the nephrology ward of a tertiary referral hospital in Shiraz, Southwest Iran

    PubMed Central

    Karimzadeh, Iman; Mirzaee, Mona; Sadeghimanesh, Niloofar; Sagheb, Mohammad Mahdi

    2016-01-01

    Objective: The aim of the present study was to determine the pattern of antimicrobial resistance of Gram-positive bacteria during three consecutive years at the nephrology ward of Namazi Hospital in Shiraz, Southwest of Iran. Methods: During a 3-year period from 2013 to 2015, data of all biological samples of hospitalized patients at the adult nephrology ward of Namazi Hospital were sent to the central laboratory for identification of Gram-positive microorganisms and subsequently, their antimicrobial susceptibility testing by Kirby–Bauer disc diffusion method were analyzed in a retrospective manner. Findings: Coagulase-negative Staphylococci (CONS) (38.5%), Staphylococcus aureus (25.4%), and Enterococcus spp. (23.8%) were the most common isolated Gram-positive bacteria from all biological samples. All Enterococcus spp. isolates within the 3 years were resistant to oxacillin. The rate of vancomycin-resistant enterococci (VRE) increased from 40.63% in 2013 to 72.73% in 2015. Enterococcus spp. resistance rates to aminoglycosides during 3 years were above 85%. The frequencies of oxacillin-resistant S. aureus (ORSA) in 2013, 2014, and 2015 were 95.24%, 80.95%, and 36.36%, respectively. Two out of 11 (6.67%) S. aureus isolates were resistant to vancomycin. More than 90% of CONS were sensitive to vancomycin within the study period. The frequency of gentamicin-resistant CONS ranged from 40% to 57.14%. Conclusion: The rates of ORSA, VRE, and aminoglycoside-resistant CONS as well as Enterococcus spp. in our clinical setting were considerably high and concerning. These may be due to the failure or lack of infection control activities and antimicrobial selection pressure. PMID:27843959

  8. Surveillance of tedizolid activity and resistance: In vitro susceptibility of Gram-positive pathogens collected over 5 years from the United States and Europe.

    PubMed

    Bensaci, Mekki; Sahm, Daniel

    2017-02-01

    In vitro activity of tedizolid and comparators against 11,231 Gram-positive clinical isolates from the United States (84 centers) and Europe (115 centers) were summarized as part of the Surveillance of Tedizolid Activity and Resistance program between 2009 and 2013. Susceptibility testing was performed according to Clinical Laboratory and Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) interpretations were based on CLSI and European Committee on Antimicrobial Susceptibility Testing criteria. Tedizolid inhibited 99.7% of all isolates at MIC ≤0.5 mg/L; activity was similar regardless of methicillin or vancomycin resistance phenotypes of Staphylococcus aureus and enterococci, respectively. Tedizolid MIC >1 mg/L was reported for 3 S. aureus, 4 coagulase-negative staphylococci, and 2 enterococcal isolates; all streptococci were inhibited at MIC ≤0.5 mg/L. Tedizolid was ≥4-fold more potent than linezolid against all groups, including resistant phenotypes. Tedizolid had potent/stable activity against a large, contemporary collection of Gram-positive clinical isolates, with low rates of resistance.

  9. Pleuromutilin derivatives having a purine ring. Part 1: new compounds with promising antibacterial activity against resistant Gram-positive pathogens.

    PubMed

    Hirokawa, Yoshimi; Kinoshita, Hironori; Tanaka, Tomoyuki; Nakamura, Takanori; Fujimoto, Koichi; Kashimoto, Shigeki; Kojima, Tsuyoshi; Kato, Shiro

    2008-06-15

    In the course of our research aimed at the discovery of metabolic stable pleuromutilin derivatives with more potent antibacterial activity against Gram-positive pathogens than previous analogues, a series of compounds bearing a purine ring were prepared and evaluated. From SAR studies, we identified two promising compounds 85 and 87, which have excellent in vitro activity against a number of Gram-positive pathogens, including existing drug-resistant strains, and potent in vivo efficacy.

  10. Peptidoglycan Recycling in Gram-Positive Bacteria Is Crucial for Survival in Stationary Phase.

    PubMed

    Borisova, Marina; Gaupp, Rosmarie; Duckworth, Amanda; Schneider, Alexander; Dalügge, Désirée; Mühleck, Maraike; Deubel, Denise; Unsleber, Sandra; Yu, Wenqi; Muth, Günther; Bischoff, Markus; Götz, Friedrich; Mayer, Christoph

    2016-10-11

    Peptidoglycan recycling is a metabolic process by which Gram-negative bacteria reutilize up to half of their cell wall within one generation during vegetative growth. Whether peptidoglycan recycling also occurs in Gram-positive bacteria has so far remained unclear. We show here that three Gram-positive model organisms, Staphylococcus aureus, Bacillus subtilis, and Streptomyces coelicolor, all recycle the sugar N-acetylmuramic acid (MurNAc) of their peptidoglycan during growth in rich medium. They possess MurNAc-6-phosphate (MurNAc-6P) etherase (MurQ in E. coli) enzymes, which are responsible for the intracellular conversion of MurNAc-6P to N-acetylglucosamine-6-phosphate and d-lactate. By applying mass spectrometry, we observed accumulation of MurNAc-6P in MurNAc-6P etherase deletion mutants but not in either the isogenic parental strains or complemented strains, suggesting that MurQ orthologs are required for the recycling of cell wall-derived MurNAc in these bacteria. Quantification of MurNAc-6P in ΔmurQ cells of S. aureus and B. subtilis revealed small amounts during exponential growth phase (0.19 nmol and 0.03 nmol, respectively, per ml of cells at an optical density at 600 nm [OD600] of 1) but large amounts during transition (0.56 nmol and 0.52 nmol) and stationary (0.53 nmol and 1.36 nmol) phases. The addition of MurNAc to ΔmurQ cultures greatly increased the levels of intracellular MurNAc-6P in all growth phases. The ΔmurQ mutants of S. aureus and B. subtilis showed no growth deficiency in rich medium compared to the growth of the respective parental strains, but intriguingly, they had a severe survival disadvantage in late stationary phase. Thus, although peptidoglycan recycling is apparently not essential for the growth of Gram-positive bacteria, it provides a benefit for long-term survival.

  11. An optimized staining technique for the detection of Gram positive and Gram negative bacteria within tissue.

    PubMed

    Becerra, Sandra C; Roy, Daniel C; Sanchez, Carlos J; Christy, Robert J; Burmeister, David M

    2016-04-12

    Bacterial infections are a common clinical problem in both acute and chronic wounds. With growing concerns over antibiotic resistance, treatment of bacterial infections should only occur after positive diagnosis. Currently, diagnosis is delayed due to lengthy culturing methods which may also fail to identify the presence of bacteria. While newer costly bacterial identification methods are being explored, a simple and inexpensive diagnostic tool would aid in immediate and accurate treatments for bacterial infections. Histologically, hematoxylin and eosin (H&E) and Gram stains have been employed, but are far from optimal when analyzing tissue samples due to non-specific staining. The goal of the current study was to develop a modification of the Gram stain that enhances the contrast between bacteria and host tissue. A modified Gram stain was developed and tested as an alternative to Gram stain that improves the contrast between Gram positive bacteria, Gram negative bacteria and host tissue. Initially, clinically relevant strains of Pseudomonas aeruginosa and Staphylococcus aureus were visualized in vitro and in biopsies of infected, porcine burns using routine Gram stain, and immunohistochemistry techniques involving bacterial strain-specific fluorescent antibodies as validation tools. H&E and Gram stain of serial biopsy sections were then compared to a modification of the Gram stain incorporating a counterstain that highlights collagen found in tissue. The modified Gram stain clearly identified both Gram positive and Gram negative bacteria, and when compared to H&E or Gram stain alone provided excellent contrast between bacteria and non-viable burn eschar. Moreover, when applied to surgical biopsies from patients that underwent burn debridement this technique was able to clearly detect bacterial morphology within host tissue. We describe a modification of the Gram stain that provides improved contrast of Gram positive and Gram negative microorganisms within host

  12. Clinical experience with linezolid in the treatment of resistant gram-positive infections.

    PubMed Central

    Antony, S. J.; Diaz-Vasquez, E.; Stratton, C.

    2001-01-01

    This study presents our clinical experience with linezolid in 19 patients with serious resistant gram-positive infections enrolled as part of the compassionate study. In this prospective, non-randomized, noncomparative study, 19 patients were enrolled as part of the National Compassionate Study Protocol conducted by Pharmacia-Upjohn. At the time of this writing, these patients had not been published in the literature. All of the patients had to have documented evidence of serious gram-positive infections in normally sterile sites and should have been unable to tolerate available antimicrobial therapy or be unresponsive to available drugs. Clinical characteristics, laboratory values, and pharmacokinetic and pharmacodynamic parameters were obtained. Patients were followed both short-term and long-term after completion of therapy. Nineteen patients were enrolled: 13 females and 6 males. The average age was 63 years. The average length of therapy with linezolid was 22 days. Methicillin-resistant Staphylococcus aureus (MRSA) was treated in eight patients, methicillin-resistant Staphylococcus epidermidis (MRSE) in two patients, vancomycin-resistant Enterococcus faecium (VREF) in eight patients, and coagulase-negative Staphylococcus in two patients. Co-infecting organisms include Enterococcus species colonization in six patients, Pseudomonas species in one patient, Serratia marcenens in one patient, and Candida albicans in one patient. Sterile sites that were infected included bone and joint (wounds and septic joints) in six patients, gastrointestinal system (hepatobiliary, liver abscess, Crohn's) in five patients, genitourinary (kidney and urine) in two patients, blood in five patients, respiratory in one patient, and aortic valve in 1 patient. Linezolid was given at 600 mg IV every 12 hours with a mean length of therapy of 22 days. Surgical drainage was used in combination with linezolid in 11 of the patients. Seventy nine percent of these patients achieved clinical and

  13. Peptidoglycan Recycling in Gram-Positive Bacteria Is Crucial for Survival in Stationary Phase

    PubMed Central

    Borisova, Marina; Gaupp, Rosmarie; Duckworth, Amanda; Schneider, Alexander; Dalügge, Désirée; Mühleck, Maraike; Deubel, Denise; Unsleber, Sandra; Yu, Wenqi; Muth, Günther; Bischoff, Markus; Götz, Friedrich

    2016-01-01

    ABSTRACT Peptidoglycan recycling is a metabolic process by which Gram-negative bacteria reutilize up to half of their cell wall within one generation during vegetative growth. Whether peptidoglycan recycling also occurs in Gram-positive bacteria has so far remained unclear. We show here that three Gram-positive model organisms, Staphylococcus aureus, Bacillus subtilis, and Streptomyces coelicolor, all recycle the sugar N-acetylmuramic acid (MurNAc) of their peptidoglycan during growth in rich medium. They possess MurNAc-6-phosphate (MurNAc-6P) etherase (MurQ in E. coli) enzymes, which are responsible for the intracellular conversion of MurNAc-6P to N-acetylglucosamine-6-phosphate and d-lactate. By applying mass spectrometry, we observed accumulation of MurNAc-6P in MurNAc-6P etherase deletion mutants but not in either the isogenic parental strains or complemented strains, suggesting that MurQ orthologs are required for the recycling of cell wall-derived MurNAc in these bacteria. Quantification of MurNAc-6P in ΔmurQ cells of S. aureus and B. subtilis revealed small amounts during exponential growth phase (0.19 nmol and 0.03 nmol, respectively, per ml of cells at an optical density at 600 nm [OD600] of 1) but large amounts during transition (0.56 nmol and 0.52 nmol) and stationary (0.53 nmol and 1.36 nmol) phases. The addition of MurNAc to ΔmurQ cultures greatly increased the levels of intracellular MurNAc-6P in all growth phases. The ΔmurQ mutants of S. aureus and B. subtilis showed no growth deficiency in rich medium compared to the growth of the respective parental strains, but intriguingly, they had a severe survival disadvantage in late stationary phase. Thus, although peptidoglycan recycling is apparently not essential for the growth of Gram-positive bacteria, it provides a benefit for long-term survival. PMID:27729505

  14. A novel combination approach of human polyclonal IVIG and antibiotics against multidrug-resistant Gram-positive bacteria

    PubMed Central

    Sallam, Mariam Madkour; Abou-Aisha, Khaled; El-Azizi, Mohamed

    2016-01-01

    Background Gram-positive bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA) and enterococci, have shown a remarkable ability to develop resistance to antimicrobial agents. Objective We aimed to assess possible enhancement of the antimicrobial activity of vancomycin, amoxicillin, clarithromycin, and azithromycin by human polyclonal intravenous immunoglobulin G (IVIG) against 34 multidrug-resistant (MDR) bacterial isolates, including MRSA, Enterococcus faecium, and Enterococcus faecalis. Materials and methods Double combinations of the antibiotics with the IVIG were assessed by checkerboard assay, where the interaction was evaluated with respect to the minimum inhibitory concentration (MIC) of the antibiotics. The results of the checkerboard assay were verified in vitro using time-kill assay and in vivo using an invasive sepsis murine model. Results The checkerboard assay showed that IVIG enhanced the antimicrobial activity of amoxicillin and clarithromycin against isolates from the three groups of bacteria, which were resistant to the same antibiotics when tested in the absence of IVIG. The efficacy of vancomycin against 15% of the tested isolates was enhanced when it was combined with the antibodies. Antagonism was demonstrated in 47% of the E. faecalis isolates when clarithromycin was combined with the IVIG. Synergism was proved in the time-kill assay when amoxicillin was combined with the antibodies; meanwhile, antagonism was not demonstrated in all tested combinations, even in combinations that showed such response in checkerboard assay. Conclusion The suggested approach is promising and could be helpful to enhance the antimicrobial activity of not only effective antibiotics but also antibiotics that have been proven to be ineffective against MDR bacteria. To our knowledge, this combinatorial approach against MDR bacteria, such as MRSA and enterococci, has not been investigated before. PMID:27994476

  15. [Bifidobacterium scardovii isolated from 2 consecutive urine samples].

    PubMed

    Guevara Nuñez, Daiana; De Paulis, Adriana N; Bertona, Eugenia; Gutiérrez, Miguel Ángel; Vay, Carlos A; Suárez, Juan P; Predari, Silvia C

    2017-07-19

    Bifidobacterium scardovii species consists of facultative anaerobic gram-positive rods whose growth is stimulated by CO2 and anaerobiosis. Exceptionally it has been associated with infections in humans. An elderly male patient with a urinary tract infection due to B. scardovii and Enterococcus faecalis is presented here; both microorganisms were isolated from two consecutive urine samples. The bacillus did not grow on standard media, but on chocolate agar incubated in CO2 and on supplemented Brucella agar in an anaerobic atmosphere, incubated for 72h at 35°C. Gram staining with abundant irregular gram-positive rods with Y-shaped ends and some gram-positive cocci alerted to its presence. The importance of the Gram stain test in urine samples with pyuria and the growth on enriched media for long periods is highlighted here. In this case, if we had not had the Gram stain test results, and had considered only the E. faecalis growth, we would have lost the major etiologic agent. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  16. Buffering Capacity and Membrane H+ Conductance of Neutrophilic and Alkalophilic Gram-Positive Bacteria

    PubMed Central

    Rius, Núria; Lorén, José G.

    1998-01-01

    Buffering capacity and membrane H+ conductance were examined in three gram-positive bacteria, Staphylococcus aureus, Bacillus subtilis, and Bacillus alcalophilus. An acid pulse technique was used to measure both parameters. The buffering capacity and membrane H+ conductance of B. alcalophilus are influenced by the pH of the medium and the culture conditions. Suspensions of B. alcalophilus cells from both H. A. medium and l-malate medium cultures grown at pH 10.5 exhibited higher values for these parameters than cells grown at pH 8.5. B. alcalophilus grown aerobically had a lower buffering capacity and a lower membrane conductance for protons than the neutrophilic bacteria S. aureus and B. subtilis. Fermenting cells exhibited significantly higher values for both variables than respiring cells. PMID:9546171

  17. Selective Inactivation of Resistant Gram-Positive Pathogens with a Light-Driven Hybrid Nanomaterial.

    PubMed

    Grüner, Malte; Tuchscherr, Lorena; Löffler, Bettina; Gonnissen, Dominik; Riehemann, Kristina; Staniford, Mark C; Kynast, Ulrich; Strassert, Cristian A

    2015-09-23

    Herein, we present a straightforward strategy to disperse highly insoluble photosensitizers in aqueous environments, without major synthetic efforts and keeping their photosensitizing abilities unaffected. A layered nanoclay was employed to adsorb and to solubilize a highly efficient yet hydrophobic Si(IV) phthalocyaninate in water. The aggregation of the photoactive dye was correlated with its photophysical properties, particularly with the ability to produce highly cytotoxic singlet oxygen. Moreover, the resulting hybrid nanomaterial is able to selectively photoinactivate Gram-positive pathogens, due to local interactions between the bacterial membranes and the negatively charged nanodiscs. Nanotoxicity assays confirmed its innocuousness toward eukaryotic cells, showing that it constitutes a new class of "phototriggered magic bullet" for the inactivation of pathogens in phototherapy, as well as in the development of coatings for self-disinfecting surfaces.

  18. Enemies and brothers in arms: Candida albicans and gram-positive bacteria.

    PubMed

    Förster, Toni M; Mogavero, Selene; Dräger, Antonia; Graf, Katja; Polke, Melanie; Jacobsen, Ilse D; Hube, Bernhard

    2016-12-01

    Candida albicans is an important human opportunistic fungal pathogen which is frequently found as part of the normal human microbiota. It is well accepted that the fungus interacts with other components of the resident microbiota and that this impacts the commensal or pathogenic outcome of C. albicans colonization. Different types of interactions, including synergism or antagonism, contribute to a complex balance between the multitude of different species. Mixed biofilms of C. albicans and streptococci are a well-studied example of a mutualistic interaction often potentiating the virulence of the individual members. In contrast, other bacteria like lactobacilli are known to antagonize C. albicans, and research has just started elucidating the mechanisms behind these interactions. This scenario is even more complicated by a third player, the host. This review focuses on interactions between C. albicans and gram-positive bacteria whose investigation will without doubt ultimately help understanding C. albicans infections. © 2016 John Wiley & Sons Ltd.

  19. Target recognition, resistance, immunity and genome mining of class II bacteriocins from Gram-positive bacteria.

    PubMed

    Kjos, Morten; Borrero, Juan; Opsata, Mona; Birri, Dagim J; Holo, Helge; Cintas, Luis M; Snipen, Lars; Hernández, Pablo E; Nes, Ingolf F; Diep, Dzung B

    2011-12-01

    Due to their very potent antimicrobial activity against diverse food-spoiling bacteria and pathogens and their favourable biochemical properties, peptide bacteriocins from Gram-positive bacteria have long been considered promising for applications in food preservation or medical treatment. To take advantage of bacteriocins in different applications, it is crucial to have detailed knowledge on the molecular mechanisms by which these peptides recognize and kill target cells, how producer cells protect themselves from their own bacteriocin (self-immunity) and how target cells may develop resistance. In this review we discuss some important recent progress in these areas for the non-lantibiotic (class II) bacteriocins. We also discuss some examples of how the current wealth of genome sequences provides an invaluable source in the search for novel class II bacteriocins.

  20. Regulating the Intersection of Metabolism and Pathogenesis in Gram-positive Bacteria

    PubMed Central

    RICHARDSON, ANTHONY R.; SOMERVILLE, GREG A.; SONENSHEIN, ABRAHAM L.

    2015-01-01

    Pathogenic bacteria must contend with immune systems that actively restrict the availability of nutrients and cofactors, and create a hostile growth environment. To deal with these hostile environments, pathogenic bacteria have evolved or acquired virulence determinants that aid in the acquisition of nutrients. This connection between pathogenesis and nutrition may explain why regulators of metabolism in nonpathogenic bacteria are used by pathogenic bacteria to regulate both metabolism and virulence. Such coordinated regulation is presumably advantageous because it conserves carbon and energy by aligning synthesis of virulence determinants with the nutritional environment. In Gram-positive bacterial pathogens, at least three metabolite-responsive global regulators, CcpA, CodY, and Rex, have been shown to coordinate the expression of metabolism and virulence genes. In this chapter, we discuss how environmental challenges alter metabolism, the regulators that respond to this altered metabolism, and how these regulators influence the host-pathogen interaction. PMID:26185086

  1. Activation and manipulation of host responses by a Gram-positive bacterium

    PubMed Central

    Balaji, Vasudevan

    2008-01-01

    The interaction between tomato plants and Clavibacter michiganensis subsp. michiganensis (Cmm) represents a model pathosystem to study the interplay between the virulence determinants of a Gram-positive bacterium and the attempt of a crop plant to counteract pathogen invasion. To investigate plant responses activated during this compatible interaction, we recently analyzed gene expression profiles of tomato stems infected with Cmm. This analysis revealed activation of basal defense responses that are typically observed upon plant perception of pathogen-associated molecular patterns. In addition, Cmm infection upregulated the expression of host genes related to ethylene synthesis and response. Further analysis of tomato plants impaired in ethylene perception and production demonstrated an important role for ethylene in the development of disease symptoms. Here we discuss possible molecular strategies used by the plant to recognize Cmm infection and possible mechanisms employed by the pathogen to interfere with the activation of plant defense responses and promote disease. PMID:19704516

  2. Purification Techniques of Bacteriocins from Lactic Acid Bacteria and Other Gram-Positive Bacteria

    NASA Astrophysics Data System (ADS)

    Saavedra, Lucila; Sesma, Fernando

    The search for new antimicrobial peptides produced by lactic acid ­bacteria and other Gram-positive microorganisms has become an interesting field of research in the past decades. The fact that bacteriocins are active against numerous foodborne and human pathogens, are produced by generally regarded as safe (GRAS) microorganisms, and are readily degraded by proteolytic host systems makes them attractive candidates for biotechnological applications. However, before suggesting or choosing a new bacteriocin for future technology developments, it is necessary to elucidate its biochemical structure and its mode of action, which may be carried out once the bacteriocin is purified to homogeneity. This chapter focuses on describing the main strategies used for the purification of numerous bacteriocins.

  3. Activation and manipulation of host responses by a Gram-positive bacterium.

    PubMed

    Balaji, Vasudevan; Sessa, Guido

    2008-10-01

    The interaction between tomato plants and Clavibacter michiganensis subsp. michiganensis (Cmm) represents a model pathosystem to study the interplay between the virulence determinants of a Gram-positive bacterium and the attempt of a crop plant to counteract pathogen invasion. To investigate plant responses activated during this compatible interaction, we recently analyzed gene expression profiles of tomato stems infected with Cmm. This analysis revealed activation of basal defense responses that are typically observed upon plant perception of pathogen-associated molecular patterns. In addition, Cmm infection upregulated the expression of host genes related to ethylene synthesis and response. Further analysis of tomato plants impaired in ethylene perception and production demonstrated an important role for ethylene in the development of disease symptoms. Here we discuss possible molecular strategies used by the plant to recognize Cmm infection and possible mechanisms employed by the pathogen to interfere with the activation of plant defense responses and promote disease.

  4. Gram-positive and gram-negative bacterial toxins in sepsis: a brief review.

    PubMed

    Ramachandran, Girish

    2014-01-01

    Bacterial sepsis is a major cause of fatality worldwide. Sepsis is a multi-step process that involves an uncontrolled inflammatory response by the host cells that may result in multi organ failure and death. Both gram-negative and gram-positive bacteria play a major role in causing sepsis. These bacteria produce a range of virulence factors that enable them to escape the immune defenses and disseminate to remote organs, and toxins that interact with host cells via specific receptors on the cell surface and trigger a dysregulated immune response. Over the past decade, our understanding of toxins has markedly improved, allowing for new therapeutic strategies to be developed. This review summarizes some of these toxins and their role in sepsis.

  5. Through the wall: extracellular vesicles in Gram-positive bacteria, mycobacteria and fungi.

    PubMed

    Brown, Lisa; Wolf, Julie M; Prados-Rosales, Rafael; Casadevall, Arturo

    2015-10-01

    Extracellular vesicles (EVs) are produced by all domains of life. In Gram-negative bacteria, EVs are produced by the pinching off of the outer membrane; however, how EVs escape the thick cell walls of Gram-positive bacteria, mycobacteria and fungi is still unknown. Nonetheless, EVs have been described in a variety of cell-walled organisms, including Staphylococcus aureus, Mycobacterium tuberculosis and Cryptococcus neoformans. These EVs contain varied cargo, including nucleic acids, toxins, lipoproteins and enzymes, and have important roles in microbial physiology and pathogenesis. In this Review, we describe the current status of vesiculogenesis research in thick-walled microorganisms and discuss the cargo and functions associated with EVs in these species.

  6. Synthesis and evaluation of isatin-β-thiosemicarbazones as novel agents against antibiotic-resistant Gram-positive bacterial species.

    PubMed

    Zhang, Xu-Meng; Guo, Hui; Li, Zai-Shun; Song, Fu-Hang; Wang, Wei-Min; Dai, Huan-Qin; Zhang, Li-Xin; Wang, Jian-Guo

    2015-08-28

    Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE) have caused an increasing mortality rate, which means that antibiotic resistance is becoming an important health issue. In the course to screen new agents for resistant bacteria, we identified that a series of isatin-β-thiosemicarbazones (IBTs) could inhibit the growth of MRSA and VRE. This was the first time that the "familiar" IBT compounds exhibited significant anti Gram-positive pathogen activity. Against a clinical isolated MRSA strain, 20 of the 51 synthesized compounds showed minimum inhibitory concentration (MIC) data of 0.78 mg/L and another 12 novel compounds had MICs of 0.39 mg/L. Moreover, these compounds also inhibited Enterococcus faecalis and VRE at similar levels, indicating that IBTs might have different mode of action compared with vancomycin. For these IBTs, comparative field analysis (CoMFA) models were further established to understand the structure-activity relationships in order to design new compounds from steric and electrostatic contributions. This work has suggested that IBTs can be considered as potential lead compounds to discover antibacterial inhibitors to combat drug resistance.

  7. Genomic Analysis of Clavibacter michiganensis Reveals Insight Into Virulence Strategies and Genetic Diversity of a Gram-Positive Bacterial Pathogen.

    PubMed

    Thapa, Shree P; Pattathil, Sivakumar; Hahn, Michael G; Jacques, Marie-Agnès; Gilbertson, Robert L; Coaker, Gitta

    2017-10-01

    Clavibacter michiganensis subsp. michiganensis is a gram-positive bacterial pathogen that proliferates in the xylem vessels of tomato, causing bacterial canker disease. In this study, we sequenced and assembled genomes of 11 C. michiganensis subsp. michiganensis strains isolated from infected tomato fields in California as well as five Clavibacter strains that colonize tomato endophytically but are not pathogenic in this host. The analysis of the C. michiganensis subsp. michiganensis genomes supported the monophyletic nature of this pathogen but revealed genetic diversity among strains, consistent with multiple introduction events. Two tomato endophytes that clustered phylogenetically with C. michiganensis strains capable of infecting wheat and pepper and were also able to cause disease in these plants. Plasmid profiles of the California strains were variable and supported the essential role of the pCM1-like plasmid and the CelA cellulase in virulence, whereas the absence of the pCM2-like plasmid in some pathogenic C. michiganensis subsp. michiganensis strains revealed it is not essential. A large number of secreted C. michiganensis subsp. michiganensis proteins were carbohydrate-active enzymes (CAZymes). Glycome profiling revealed that C. michiganensis subsp. michiganensis but not endophytic Clavibacter strains is able to extensively alter tomato cell-wall composition. Two secreted CAZymes found in all C. michiganensis subsp. michiganensis strains, CelA and PelA1, enhanced pathogenicity on tomato. Collectively, these results provide a deeper understanding of C. michiganensis subsp. michiganensis diversity and virulence strategies.

  8. Design, synthesis, and characterization of novel tetrahydropyran-based bacterial topoisomerase inhibitors with potent anti-gram-positive activity.

    PubMed

    Surivet, Jean-Philippe; Zumbrunn, Cornelia; Rueedi, Georg; Hubschwerlen, Christian; Bur, Daniel; Bruyère, Thierry; Locher, Hans; Ritz, Daniel; Keck, Wolfgang; Seiler, Peter; Kohl, Christopher; Gauvin, Jean-Christophe; Mirre, Azely; Kaegi, Verena; Dos Santos, Marina; Gaertner, Mika; Delers, Jonathan; Enderlin-Paput, Michel; Boehme, Maria

    2013-09-26

    There is an urgent need for new antibacterial drugs that are effective against infections caused by multidrug-resistant pathogens. Novel nonfluoroquinolone inhibitors of bacterial type II topoisomerases (DNA gyrase and topoisomerase IV) have the potential to become such drugs because they display potent antibacterial activity and exhibit no target-mediated cross-resistance with fluoroquinolones. Bacterial topoisomerase inhibitors that are built on a tetrahydropyran ring linked to a bicyclic aromatic moiety through a syn-diol linker show potent anti-Gram-positive activity, covering isolates with clinically relevant resistance phenotypes. For instance, analog 49c was found to be a dual DNA gyrase-topoisomerase IV inhibitor, with broad antibacterial activity and low propensity for spontaneous resistance development, but suffered from high hERG K(+) channel block. On the other hand, analog 49e displayed lower hERG K(+) channel block while retaining potent in vitro antibacterial activity and acceptable frequency for resistance development. Furthermore, analog 49e showed moderate clearance in rat and promising in vivo efficacy against Staphylococcus aureus in a murine infection model.

  9. Effects of Growth Phase and Extracellular Slime on Photodynamic Inactivation of Gram-Positive Pathogenic Bacteria

    PubMed Central

    Gad, Faten; Zahra, Touqir; Hasan, Tayyaba; Hamblin, Michael R.

    2004-01-01

    The emergence of antibiotic resistance among pathogenic bacteria has led to efforts to find alternative antimicrobial therapeutics to which bacteria will not be easily able to develop resistance. One of these may be the combination of nontoxic dyes (photosensitizers [PS]) and visible light, known as photodynamic therapy, and we have reported its use to treat localized infections in animal models. While it is known that gram-positive species are generally susceptible to photodynamic inactivation (PDI), the factors that govern variation in degrees of killing are unknown. We used isogenic pairs of wild-type and transposon mutants deficient in capsular polysaccharide and slime production generated from Staphylococcus epidermidis and Staphylococcus aureus to examine the effects of extracellular slime on susceptibility to PDI mediated by two cationic PS (a polylysine-chlorine6 conjugate, pL-ce6, and methylene blue [MB]) and an anionic molecule, free ce6, and subsequent exposure to 665-nm light at 0 to 40 J/cm2. Free ce6 gave more killing of mutant strains than wild type, despite the latter taking up more PS. Log-phase cultures were killed more than stationary-phase cultures, and this correlated with increased uptake. The cationic pL-ce6 and MB gave similar uptakes and killing despite a 50-fold difference in incubation concentration. Differences in susceptibility between strains and between growth phases observed with free ce6 largely disappeared with the cationic compounds despite significant differences in uptake. These data suggest that slime production and stationary phase can be obstacles against PDI for gram-positive bacteria but that these obstacles can be overcome by using cationic PS. PMID:15155218

  10. Recognition of U-rich RNA by Hfq from the Gram-positive pathogen Listeria monocytogenes

    DOE PAGES

    Kovach, Alexander R.; Hoff, Kirsten E.; Canty, John T.; ...

    2014-08-22

    Hfq is a post-transcriptional regulator that binds U- and A-rich regions of sRNAs and their target mRNAs to stimulate their annealing in order to effect translation regulation and, often, to alter their stability. The functional importance of Hfq and its RNA-binding properties are relatively well understood in Gram-negative bacteria, whereas less is known about the RNAbinding properties of this riboregulator in Gram-positive species. Here, we describe the structure of Hfq from the Grampositive pathogen Listeria monocytogenes in its RNA-free form and in complex with a U6 oligoribonucleotide. As expected, the protein takes the canonical hexameric toroidal shape of all othermore » known Hfq structures. The U6 RNA binds on the “proximal face” in a pocket formed by conserved residues Q9, N42, F43, and K58. Additionally residues G5 and Q6 are involved in protein-nucleic and inter-subunit contacts that promote uracil specificity. Unlike Staphylococcus aureus (Sa) Hfq, Lm Hfq requires magnesium to bind U6 with high affinity. In contrast, the longer oligo-uridine, U16, binds Lm Hfq tightly in the presence or absence of magnesium, thereby suggesting the importance of additional residues on the proximal face and possibly the lateral rim in RNA interaction. Lastly, intrinsic tryptophan fluorescence quenching (TFQ) studies reveal, surprisingly, that Lm Hfq can bind (GU)3G and U6 on its proximal and distal faces, indicating a less stringent adenine-nucleotide specificity site on the distal face as compared to the Gram-positive Hfq proteins from Sa and Bacillus subtilis and suggesting as yet uncharacterized RNA-binding modes on both faces.« less

  11. The unique regulation of iron-sulfur cluster biogenesis in a Gram-positive bacterium.

    PubMed

    Santos, Joana A; Alonso-García, Noelia; Macedo-Ribeiro, Sandra; Pereira, Pedro José Barbosa

    2014-06-03

    Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators.

  12. An Export-Specific Reporter Designed for Gram-Positive Bacteria: Application to Lactococcus lactis

    PubMed Central

    Poquet, Isabelle; Ehrlich, S. Dusko; Gruss, Alexandra

    1998-01-01

    The identification of exported proteins by fusion studies, while well developed for gram-negative bacteria, is limited for gram-positive bacteria, in part due to drawbacks of available export reporters. In this work, we demonstrate the export specificity and use of the Staphylococcus aureus secreted nuclease (Nuc) as a reporter for gram-positive bacteria. Nuc devoid of its export signal (called ΔSPNuc) was used to create two fusions whose locations could be differentiated. Nuclease activity was shown to require an extracellular location in Lactococcus lactis, thus demonstrating the suitability of ΔSPNuc to report protein export. The shuttle vector pFUN was designed to construct ΔSPNuc translational fusions whose expression signals are provided by inserted DNA. The capacity of ΔSPNuc to reveal and identify exported proteins was tested by generating an L. lactis genomic library in pFUN and by screening for Nuc activity directly in L. lactis. All ΔSPNuc fusions displaying a strong Nuc+ phenotype contained a classical or a lipoprotein-type signal peptide or single or multiple transmembrane stretches. The function of some of the predicted signals was confirmed by cell fractionation studies. The fusions analyzed included long (up to 455-amino-acid) segments of the exported proteins, all previously unknown in L. lactis. Homology searches indicate that several of them may be implicated in different cell surface functions, such as nutrient uptake, peptidoglycan assembly, environmental sensing, and protein folding. Our results with L. lactis show that ΔSPNuc is well suited to report both protein export and membrane protein topology. PMID:9537391

  13. Development of methionyl-tRNA synthetase inhibitors as antibiotics for Gram-positive bacterial infections.

    PubMed

    Faghih, Omeed; Zhang, Zhongsheng; Ranade, Ranae M; Gillespie, J Robert; Creason, Sharon A; Huang, Wenlin; Shibata, Sayaka; Barros-Álvarez, Ximena; Verlinde, Christophe L M J; Hol, Wim G J; Fan, Erkang; Buckner, Frederick S

    2017-08-28

    Antibiotic resistant bacteria are widespread and pose a growing threat to human health. New antibiotics acting by novel mechanisms of action are needed to combat this threat. The bacterial methionyl-tRNA synthetase (MetRS) enzyme is essential for protein synthesis and the type found in Gram-positive bacteria is substantially different from its counterpart found in the mammalian cytoplasm. Selective inhibitors, both previously published and new, were shown to be highly active on Gram positive bacteria with minimum inhibitory concentrations (MICs) ≤ 1.3 μg/mL against Staphylococcus, Enterococcus, and Streptococcus strains. Incorporation of radioactive precursors demonstrated the mechanism of activity was due to inhibition of protein synthesis. Little activity was observed against Gram-negative bacteria, consistent with Gram-negative species containing a different type of MetRS enzyme. The ratio of MIC to minimum bactericidal concentrations (MBC) was consistent with a bacteriostatic mechanism. Protein binding was high (>95%) for the compounds and this translated to a substantial increase in MICs when tested in the presence of plasma. Despite this, the compounds were very active when tested in the Staphylococcus aureus murine thigh infection model. Compounds 1717 and 2144 given by oral gavage resulted in 3-4-log decreases in bacterial load compared to vehicle-treated mice which was comparable to results observed with the comparator drugs, vancomycin and linezolid. In summary, the research describes MetRS inhibitors with oral bioavailability that represent a class of compounds acting by a novel mechanism with excellent potential for clinical development. Copyright © 2017 American Society for Microbiology.

  14. N-acetylcysteine inhibits growth, adhesion and biofilm formation of Gram-positive skin pathogens.

    PubMed

    Eroshenko, Daria; Polyudova, Tatyana; Korobov, Vladimir

    2017-04-01

    N-Acetylcysteine (NAC) is a non-antibiotic drug with antimicrobial properties against biofilm phenotypes of Gram-positive and Gram-negative bacteria. Our aim was to assess the effects of NAC on the growth of Gram-positive human skin and mucous membrane pathogens in the planktonic and biofilm phases. The minimum inhibitory concentrations (MICs) of NAC against Enterococcus faecalis, Corynebacterium ammoniagenes, Mycobacterium smegmatis, Propionibacterium acnes, Staphylococcus aureus, S. epidermidis, Streptococcus pyogenes, and 14 clinical strains of coagulase-negative staphylococci (CNS) ranged from 0.098 to 25 mg/ml. We found that at sub-MICs of NAC the adherence of E. faecalis, S. epidermidis, and nine CNS strains significantly reduced. However, biofilm formation of E. faecalis, S. aureus and two CNS strains increased at sub-MICs of NAC. Furthermore, a dose-related decrease in biofilm formation of C. ammoniagenes, M. smegmatis, P. acnes, S. pyogenes, and S. epidermidis was observed. The effect of NAC on planktonic growth and biofilm formation of the M. smegmatis cell was also time-dependent. We have selected P. acnes VKM Ac-1450 Rif(r) strain with total resistance to rifampicin and used this microorganism for multispecies P. acnes - S. epidermidis biofilm model. The biofilm formation and growth of mixed culture of P. acnes and S. epidermidis was significantly slowed at 12.5 mg/ml of NAC. NAC also has a higher disruptive effect on both mature M. smegmatis and mixed P. acnes - S. epidermidis biofilm. Thus, NAC appears to be a promising, non-antibiotic alternative to prevent biofilm-associated infections. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Influence of bentonite particles on representative gram negative and gram positive bacterial deposition in porous media.

    PubMed

    Yang, Haiyan; Tong, Meiping; Kim, Hyunjung

    2012-11-06

    The significance of clay particles on the transport and deposition kinetics of bacteria in irregular quartz sand was examined by direct comparison of both breakthrough curves and retained profiles with clay particles in bacteria suspension versus those without clay particles. Two representative cell types, Gram-negative strain E. coli DH5α and Gram-positive strain Bacillus subtilis were utilized to systematically determine the influence of clay particles (bentonite) on cell transport behavior. Packed column experiments for both cell types were conducted in both NaCl (5 and 25 mM ionic strengths) and CaCl(2) (5 mM ionic strength) solutions at pH 6.0. The breakthrough plateaus with bentonite in solutions (30 mg L(-1) and 50 mg L(-1)) were lower than those without bentonite for both cell types under all examined conditions, indicating that bentonite in solutions decreased cell transport in porous media regardless of cell types (Gram-negative or Gram-positive) and solution chemistry (ionic strength and ion valence). The enhanced cell deposition with bentonite particles was mainly observed at segments near to column inlet, retained profiles for both cell types with bentonite particles were therefore steeper relative to those without bentonite. The increased cell deposition with bentonite observed in NaCl solutions was attributed to the codeposition of bacteria with bentonite particles whereas, in addition to codeposition of bacteria with bentonite, the bacteria-bentonite-bacteria cluster formed in suspensions also contributed to the increased deposition of bacteria with bentonite in CaCl(2) solution.

  16. The unique regulation of iron-sulfur cluster biogenesis in a Gram-positive bacterium

    PubMed Central

    Santos, Joana A.; Alonso-García, Noelia; Macedo-Ribeiro, Sandra; Pereira, Pedro José Barbosa

    2014-01-01

    Iron-sulfur clusters function as cofactors of a wide range of proteins, with diverse molecular roles in both prokaryotic and eukaryotic cells. Dedicated machineries assemble the clusters and deliver them to the final acceptor molecules in a tightly regulated process. In the prototypical Gram-negative bacterium Escherichia coli, the two existing iron-sulfur cluster assembly systems, iron-sulfur cluster (ISC) and sulfur assimilation (SUF) pathways, are closely interconnected. The ISC pathway regulator, IscR, is a transcription factor of the helix-turn-helix type that can coordinate a [2Fe-2S] cluster. Redox conditions and iron or sulfur availability modulate the ligation status of the labile IscR cluster, which in turn determines a switch in DNA sequence specificity of the regulator: cluster-containing IscR can bind to a family of gene promoters (type-1) whereas the clusterless form recognizes only a second group of sequences (type-2). However, iron-sulfur cluster biogenesis in Gram-positive bacteria is not so well characterized, and most organisms of this group display only one of the iron-sulfur cluster assembly systems. A notable exception is the unique Gram-positive dissimilatory metal reducing bacterium Thermincola potens, where genes from both systems could be identified, albeit with a diverging organization from that of Gram-negative bacteria. We demonstrated that one of these genes encodes a functional IscR homolog and is likely involved in the regulation of iron-sulfur cluster biogenesis in T. potens. Structural and biochemical characterization of T. potens and E. coli IscR revealed a strikingly similar architecture and unveiled an unforeseen conservation of the unique mechanism of sequence discrimination characteristic of this distinctive group of transcription regulators. PMID:24847070

  17. Ultrasound-Mediated DNA Transformation in Thermophilic Gram-Positive Anaerobes

    PubMed Central

    Ji, Yuetong; He, Zhili; Pu, Yunting; Zhou, Jizhong; Xu, Jian

    2010-01-01

    Background Thermophilic, Gram-positive, anaerobic bacteria (TGPAs) are generally recalcitrant to chemical and electrotransformation due to their special cell-wall structure and the low intrinsic permeability of plasma membranes. Methodology/Principal Findings Here we established for any Gram-positive or thermophiles an ultrasound-based sonoporation as a simple, rapid, and minimally invasive method to genetically transform TGPAs. We showed that by applying a 40 kHz ultrasound frequency over a 20-second exposure, Texas red-conjugated dextran was delivered with 27% efficiency into Thermoanaerobacter sp. X514, a TGPA that can utilize both pentose and hexose for ethanol production. Experiments that delivered plasmids showed that host-cell viability and plasmid DNA integrity were not compromised. Via sonoporation, shuttle vectors pHL015 harboring a jellyfish gfp gene and pIKM2 encoding a Clostridium thermocellum β-1,4-glucanase gene were delivered into X514 with an efficiency of 6×102 transformants/µg of methylated DNA. Delivery into X514 cells was confirmed via detecting the kanamycin-resistance gene for pIKM2, while confirmation of pHL015 was detected by visualization of fluorescence signals of secondary host-cells following a plasmid-rescue experiment. Furthermore, the foreign β-1,4-glucanase gene was functionally expressed in X514, converting the host into a prototypic thermophilic consolidated bioprocessing organism that is not only ethanologenic but cellulolytic. Conclusions/Significance In this study, we developed an ultrasound-based sonoporation method in TGPAs. This new DNA-delivery method could significantly improve the throughput in developing genetic systems for TGPAs, many of which are of industrial interest yet remain difficult to manipulate genetically. PMID:20838444

  18. Microcins from Enterobacteria: On the Edge Between Gram-Positive Bacteriocins and Colicins

    NASA Astrophysics Data System (ADS)

    Rebuffat, Sylvie

    Most bacteria and archaea produce gene-encoded antimicrobial peptides/proteins called bacteriocins, which are secreted by the producing bacteria to compete against other microorganisms in a given niche. They are considered important mediators of intra- and interspecies interactions and therefore a factor in ­maintaining the microbial diversity and stability. They are ribosomally synthesized, and most of them are produced as inactive precursor proteins, which in some cases are further enzymatically modified. Bacteriocins generally exert potent antibacterial activities directed against bacterial species closely related to the producing bacteria. Bacteriocins are abundant and diverse in Gram-negative and Gram-positive bacteria. This chapter focuses on colicins and microcins from enterobacteria (mainly Escherichia coli) and on bacteriocins from lactic acid bacteria (LAB). Microcins are the lower-molecular-mass bacteriocins produced by Gram-negative bacteria with a repertoire of only 14 representatives. They form a very restricted family of bacteriocins, compared to the huge family of LAB bacteriocins that is constituted of several hundreds of peptides, with which microcins share common characteristics. Nevertheless, microcins also show similarities, particularly in their uptake mechanisms, with the higher-molecular-mass colicins, also produced by E. coli strains. On the edge between LAB bacteriocins and colicins, microcins appear to combine highly efficient strategies developed by both Gram-positive and Gram-negative bacteria at different levels, including uptake, translocation, killing of target cells, and immunity of the producing bacteria, making them important actors of bacterial competitions and fascinating models for novel concepts toward antimicrobial strategies and against resistance mechanisms.

  19. The immune response after stimulation with wall components of gram-positive bacteria and fungi.

    PubMed

    Tsigou, Evdoxia; Aloizos, Stavros; Stavros, Aloizos; Myrianthefs, Pavlos; Pavlos, Myrianthefs; Gourgiotis, Stavros; Stavros, Gourgiotis; Tsakris, Athanassios; Athanassios, Tsakris; Baltopoulos, George; George, Baltopoulos

    2014-01-01

    Although several components of the microbial wall of gram-positive bacteria and fungi possess immunostimulatory properties, their pathogenetic role remains incompletely evaluated. The purpose of this study was to assess the basic immune status of patients susceptible to infections and their capability for cytokine production after stimulation with wall components of gram-positive bacteria and fungi. We measured serum cytokine levels as well as cytokine production after ex vivo lipoteichoic acid (LTA) and mannan stimulation of whole blood. The blood was taken from 10 healthy volunteers, 10 patients with end-stage renal disease (ESRD), 10 patients with diabetes mellitus (DM), and 10 patients on their 2nd day of stay in the Intensive Care Unit (ICU), who suffered from non septic systemic inflammatory response syndrome (SIRS) and had an APACHE II score ≥25. We used 1 μg/ml LTA and 100 μg/ml mannan for an incubation period of 8 h to stimulate 100 μl aliquots of whole blood. All patient groups had higher baseline values of TNF-α, IL-6, IL-1β, and IL-10 compared to the control group, but only for ICU patients the difference was statistically significant. The ratio IL-10/IL-6 was found 0.33, 0.22, and 0.96 in healthy persons, ESRD, and DM patients respectively, and 1.32 in ICU patients. In all examined groups, the levels of cytokines significantly increased after stimulation by LTA and mannan, although in severely ill patients this change was considerably smaller, possibly reflecting a state of monocytes' depression and relative hyporesponsiveness. No significant differences between the LTA and the mannan stimulation were observed. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Isolation and characterization of halophilic lactic acid bacteria isolated from "terasi" shrimp paste: a traditional fermented seafood product in Indonesia.

    PubMed

    Kobayashi, Takeshi; Kajiwara, Michika; Wahyuni, Mita; Kitakado, Toshihide; Hamada-Sato, Naoko; Imada, Chiaki; Watanabe, Etsuo

    2003-10-01

    Lactic acid bacteria from "terasi" shrimp paste, a highly popular fermented seafood in Indonesia were isolated and characterized. Viable cell counts were 10(4) to 10(6) cfu/g on MRS medium. All the isolates were catalase-negative, gram-positive cocci and were able to grow at 15% NaCl. Numerical phenotypic analysis showed that the isolates clustered into one group. However, they could be classified into two types: the Tetragenococcus halophilus group and the T. muriaticus group as revealed by a restriction fragment length polymorphism (RFLP) analysis and sequencing of the 16S rRNA gene. This study is the first to show that both species of Tetragenococcus are distributed in Indonesian fermented foods.

  1. Evaluation of the nanosphere verigene gram-positive blood culture assay with the VersaTREK blood culture system and assessment of possible impact on selected patients.

    PubMed

    Beal, Stacy G; Ciurca, Jane; Smith, Geremy; John, Jeffrey; Lee, Francesca; Doern, Christopher D; Gander, Rita M

    2013-12-01

    The Verigene Gram-positive blood culture (BC-GP) assay (Nanosphere, Northbrook, IL) is a molecular method for the rapid identification of Gram-positive organisms and resistance markers directly from blood culture bottles. A total of 148 VersaTREK REDOX 1 40-ml aerobic bottles demonstrating Gram-positive bacteria were tested. Results were compared with those from conventional biochemical and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) identifications. We obtained isolates of methicillin-resistant Staphylococcus aureus (MRSA) (24), methicillin-susceptible Staphylococcus aureus (MSSA) (14), methicillin-resistant Staphylococcus epidermidis (MRSE) (17), methicillin-susceptible Staphylococcus epidermidis (MSSE) (9), other coagulase-negative staphylococci (19), Streptococcus salivarius (5), Streptococcus parasanguinis (2), Streptococcus sanguinis (1), Streptococcus cristatus (1), the Streptococcus bovis group (5), Streptococcus agalactiae (9), the Streptococcus anginosus group (1), Streptococcus pneumoniae (6), vancomycin-resistant Enterococcus faecium (VRE FCM) (16), vancomycin-susceptible Enterococcus faecalis (3), Aerococcus viridans (2), Bacillus (6), Corynebacterium (8), Lactobacillus (2), Micrococcus (2), Neisseria mucosa (1), Escherichia coli (3), Candida tropicalis (1), Propionibacterium (1), and Rothia (1). Overall agreement with the culture results was 95%. A total of 137 of 138 (99%) monomicrobial cultures were concordant. We tested 9 polymicrobial samples and found 33% agreement. A chart review of 31 patients with MRSA, MSSA, or VRE demonstrated that the Nanosphere BC-GP assay might have led to more appropriate antibiotic selection for these patients an average of 42 h earlier. Additionally, contact isolation could have been initiated an average of 37 h earlier for patients with MRSA or VRE. The BC-GP assay may have a positive impact on patient care, health care costs, and antibiotic stewardship.

  2. In Vitro Activity of AZD0914, a Novel Bacterial DNA Gyrase/Topoisomerase IV Inhibitor, against Clinically Relevant Gram-Positive and Fastidious Gram-Negative Pathogens

    PubMed Central

    Huband, Michael D.; Hackel, Meredith; de Jonge, Boudewijn L. M.; Sahm, Daniel F.; Bradford, Patricia A.

    2015-01-01

    AZD0914, a new spiropyrimidinetrione bacterial DNA gyrase inhibitor with a novel mode of inhibition, has activity against bacterial species commonly cultured from patient infection specimens, including fluoroquinolone-resistant isolates. This study assessed the in vitro activity of AZD0914 against key Gram-positive and fastidious Gram-negative clinical isolates collected globally in 2013. AZD0914 demonstrated potent activity, with MIC90s for AZD0914 of 0.25 mg/liter against Staphylococcus aureus (n = 11,680), coagulase-negative staphylococci (n = 1,923), streptococci (n = 4,380), and Moraxella catarrhalis (n = 145), 0.5 mg/liter against Staphylococcus lugdunensis (n = 120) and Haemophilus influenzae (n = 352), 1 mg/liter against Enterococcus faecalis (n = 1,241), and 2 mg/liter against Haemophilus parainfluenzae (n = 70). The activity against Enterococcus faecium was more limited (MIC90, 8 mg/liter). The spectrum and potency of AZD0914 included fluoroquinolone-resistant isolates in each species group, including methicillin-resistant staphylococci, penicillin-resistant streptococci, vancomycin-resistant enterococci, β-lactamase-producing Haemophilus spp., and M. catarrhalis. Based on these in vitro findings, AZD0914 warrants further investigation for its utility against a variety of Gram-positive and fastidious Gram-negative bacterial species. PMID:26195518

  3. Sequence-Based Characterization of Tn5801-Like Genomic Islands in Tetracycline-Resistant Staphylococcus pseudintermedius and Other Gram-positive Bacteria from Humans and Animals

    PubMed Central

    de Vries, Lisbeth E.; Hasman, Henrik; Jurado Rabadán, Sonia; Agersø, Yvonne

    2016-01-01

    Antibiotic resistance in pathogens is often associated with mobile genetic elements, such as genomic islands (GI) including integrative and conjugative elements (ICEs). These can transfer resistance genes within and between bacteria from humans and/or animals. The aim of this study was to investigate whether Tn5801-like GIs carrying the tetracycline resistance gene, tet(M), are common in Staphylococcus pseudintermedius from pets, and to do an overall sequences-based characterization of Tn5801-like GIs detected in Gram-positive bacteria from humans and animals. A total of 27 tetracycline-resistant S. pseudintermedius isolates from Danish pets (1998–2005) were screened for tet(M) by PCR. Selected isolates (13) were screened for GI- or ICE-specific genes (intTn5801 or xisTn916) and their tet(M) gene was sequenced (Sanger-method). Long-range PCR mappings and whole-genome-sequencing (Illumina) were performed for selected S. pseudintermedius-isolates (seven and three isolates, respectively) as well as for human S. aureus isolates (seven and one isolates, respectively) and one porcine Enterococcus faecium isolate known to carry Tn5801-like GIs. All 27 S. pseudintermedius were positive for tet(M). Out of 13 selected isolates, seven contained Tn5801-like GIs and six contained Tn916-like ICEs. Two different Tn5801-like GI types were detected among S. pseudintermedius (Tn5801 and GI6287) - both showed high similarity compared to GenBank sequences from human pathogens. Two distinct Tn5801-like GI types were detected among the porcine E. faecium and human S. aureus isolates (Tn6014 and GI6288). Tn5801-like GIs were detected in GenBank-sequences from Gram-positive bacteria of human, animal or food origin worldwide. Known Tn5801-like GIs were divided into seven types. The results showed that Tn5801-like GIs appear to be relatively common in tetracycline-resistant S. pseudintermedius in Denmark. Almost identical Tn5801-like GIs were identified in different Gram-positive species

  4. Sequence-Based Characterization of Tn5801-Like Genomic Islands in Tetracycline-Resistant Staphylococcus pseudintermedius and Other Gram-positive Bacteria from Humans and Animals.

    PubMed

    de Vries, Lisbeth E; Hasman, Henrik; Jurado Rabadán, Sonia; Agersø, Yvonne

    2016-01-01

    Antibiotic resistance in pathogens is often associated with mobile genetic elements, such as genomic islands (GI) including integrative and conjugative elements (ICEs). These can transfer resistance genes within and between bacteria from humans and/or animals. The aim of this study was to investigate whether Tn5801-like GIs carrying the tetracycline resistance gene, tet(M), are common in Staphylococcus pseudintermedius from pets, and to do an overall sequences-based characterization of Tn5801-like GIs detected in Gram-positive bacteria from humans and animals. A total of 27 tetracycline-resistant S. pseudintermedius isolates from Danish pets (1998-2005) were screened for tet(M) by PCR. Selected isolates (13) were screened for GI- or ICE-specific genes (int Tn5801 or xis Tn916 ) and their tet(M) gene was sequenced (Sanger-method). Long-range PCR mappings and whole-genome-sequencing (Illumina) were performed for selected S. pseudintermedius-isolates (seven and three isolates, respectively) as well as for human S. aureus isolates (seven and one isolates, respectively) and one porcine Enterococcus faecium isolate known to carry Tn5801-like GIs. All 27 S. pseudintermedius were positive for tet(M). Out of 13 selected isolates, seven contained Tn5801-like GIs and six contained Tn916-like ICEs. Two different Tn5801-like GI types were detected among S. pseudintermedius (Tn5801 and GI6287) - both showed high similarity compared to GenBank sequences from human pathogens. Two distinct Tn5801-like GI types were detected among the porcine E. faecium and human S. aureus isolates (Tn6014 and GI6288). Tn5801-like GIs were detected in GenBank-sequences from Gram-positive bacteria of human, animal or food origin worldwide. Known Tn5801-like GIs were divided into seven types. The results showed that Tn5801-like GIs appear to be relatively common in tetracycline-resistant S. pseudintermedius in Denmark. Almost identical Tn5801-like GIs were identified in different Gram-positive species

  5. Evaluation of Three Bacterial Identification Systems for Species Identification of Bacteria Isolated from Bovine Mastitis and Bulk Tank Milk Samples.

    PubMed

    Savage, Emily; Chothe, Shubhada; Lintner, Valerie; Pierre, Traci; Matthews, Tammy; Kariyawasam, Subhashinie; Miller, Dawn; Tewari, Deepanker; Jayarao, Bhushan

    2017-03-01

    A study was conducted to evaluate Sensititre(®) Automated Reading and Incubation System 2x System (ARIS), API(®) (API), and Bruker MALDI-TOF MS (MALDI) bacterial species identification systems using 132 diverse bacterial isolates from bovine milk samples and bulk tank milk received at the Penn State Animal Diagnostic Laboratory. The results were compared with 16S rRNA gene sequence analysis, which served as the reference method for species identification. The ARIS, API, and MALDI identified 0%, 40%, and 33.4% of species classified as Gram-positive rod isolates belonging to genera Arthrobacter, Bacillus, Brachybacterium, Brevibacterium, and Corynebacterium, respectively. It was observed that 76.5%, 93.9%, and 96.9% of catalase-negative, Gram-positive cocci (n = 33; Aerococcus, Enterococcus, Lactococcus, Streptococcus) were correctly identified to the species level by ARIS, API, and MALDI, respectively, while 33.4%, 84.5%, and 97.7% of catalase-positive, Gram-positive cocci (n = 45; Kocuria, Staphylococcus) were correctly identified to their species by ARIS, API, and MALDI, respectively. A total of 48 isolates (Acinetobacter, Citrobacter, Enterobacter, Escherichia, Klebsiella, Pantoea, Pasteurella, Providencia, Pseduomonas, Serratia) of Gram-negative bacteria were examined, of which 85.4%, 93.7%, and 95.8% of the isolates were correctly identified to the species level by ARIS, API, and MALDI, respectively. In our laboratory, the MALDI had the least costs associated with consumables and reagents compared to ARIS, API, and 16S rRNA identification methods. Identification of bacterial species was accomplished in <2 h using MALDI and 24 h for ARIS, API, and 16S rRNA identification systems.

  6. Comparison of antimicrobial pharmacokinetic/pharmacodynamic breakpoints with EUCAST and CLSI clinical breakpoints for Gram-positive bacteria.

    PubMed

    Asín, Eduardo; Isla, Arantxazu; Canut, Andrés; Rodríguez Gascón, Alicia

    2012-10-01

    This study compared the susceptibility breakpoints based on pharmacokinetic/pharmacodynamic (PK/PD) models and Monte Carlo simulation with those defined by the Clinical and Laboratory Standards Institute (CLSI) and the European Committee on Antimicrobial Susceptibility Testing (EUCAST) for antibiotics used for the treatment of infections caused by Gram-positive bacteria. A secondary objective was to evaluate the probability of achieving the PK/PD target associated with the success of antimicrobial therapy. A 10,000-subject Monte Carlo simulation was executed to evaluate 13 antimicrobials (47 intravenous dosing regimens). Susceptibility data were extracted from the British Society for Antimicrobial Chemotherapy database for bacteraemia isolates. The probability of target attainment and the cumulative fraction of response (CFR) were calculated. No antibiotic was predicted to be effective (CFR≥90%) against all microorganisms. The PK/PD susceptibility breakpoints were also estimated and were compared with CLSI and EUCAST breakpoints. The percentages of strains affected by breakpoint discrepancies were calculated. In the case of β-lactams, breakpoint discrepancies affected <15% of strains. However, higher differences were detected for low doses of vancomycin, daptomycin and linezolid, with PK/PD breakpoints being lower than those defined by the CLSI and EUCAST. If this occurs, an isolate will be considered susceptible based on CLSI and EUCAST breakpoints although the PK/PD analysis predicts failure, which may explain treatment failures reported in the literature. This study reinforces the idea of considering not only the antimicrobial activity but also the dosing regimen to increase the probability of clinical success of an antimicrobial treatment.

  7. Higher platelet reactivity and platelet-monocyte complex formation in Gram-positive sepsis compared to Gram-negative sepsis.

    PubMed

    Tunjungputri, Rahajeng N; van de Heijden, Wouter; Urbanus, Rolf T; de Groot, Philip G; van der Ven, Andre; de Mast, Quirijn

    2016-12-29

    Platelets may play a role in the high risk for vascular complications in Gram-positive sepsis. We compared the platelet reactivity of 15 patients with Gram-positive sepsis, 17 with Gram-negative sepsis and 20 healthy controls using a whole blood flow cytometry-based assay. Patients with Gram-positive sepsis had the highest median fluorescence intensity (MFI) of the platelet membrane expression of P-selectin upon stimulation with high dose adenosine diphosphate (ADP; P = 0.002 vs. Gram-negative and P = 0.005 vs. control groups) and cross-linked collagen-related peptide (CRP-XL; P = 0.02 vs. Gram-negative and P = 0.0001 vs. control groups). The Gram-positive group also demonstrated significantly higher ADP-induced fibrinogen binding (P = 0.001), as wll as platelet-monocyte complex formation (P = 0.02), compared to the Gram-negative group and had the highest plasma levels of platelet factor 4, β-thromboglobulin and soluble P-selectin. In contrast, thrombin-antithrombin complex and C-reactive protein levels were comparable in both patient groups. In conclusion, common Gram-positive pathogens induce platelet hyperreactivity, which may contribute to a higher risk for vascular complications.

  8. Transport capabilities of eleven gram-positive bacteria: comparative genomic analyses.

    PubMed

    Lorca, Graciela L; Barabote, Ravi D; Zlotopolski, Vladimir; Tran, Can; Winnen, Brit; Hvorup, Rikki N; Stonestrom, Aaron J; Nguyen, Elizabeth; Huang, Li-Wen; Kim, David S; Saier, Milton H

    2007-06-01

    The genomes of eleven Gram-positive bacteria that are important for human health and the food industry, nine low G+C lactic acid bacteria and two high G+C Gram-positive organisms, were analyzed for their complement of genes encoding transport proteins. Thirteen to 18% of their genes encode transport proteins, larger percentages than observed for most other bacteria. All of these bacteria possess channel proteins, some of which probably function to relieve osmotic stress. Amino acid uptake systems predominate over sugar and peptide cation symporters, and of the sugar uptake porters, those specific for oligosaccharides and glycosides often outnumber those for free sugars. About 10% of the total transport proteins are constituents of putative multidrug efflux pumps with Major Facilitator Superfamily (MFS)-type pumps (55%) being more prevalent than ATP-binding cassette (ABC)-type pumps (33%), which, however, usually greatly outnumber all other types. An exception to this generalization is Streptococcus thermophilus with 54% of its drug efflux pumps belonging to the ABC superfamily and 23% belonging each to the Multidrug/Oligosaccharide/Polysaccharide (MOP) superfamily and the MFS. These bacteria also display peptide efflux pumps that may function in intercellular signalling, and macromolecular efflux pumps, many of predictable specificities. Most of the bacteria analyzed have no pmf-coupled or transmembrane flow electron carriers. The one exception is Brevibacterium linens, which in addition to these carriers, also has transporters of several families not represented in the other ten bacteria examined. Comparisons with the genomes of organisms from other bacterial kingdoms revealed that lactic acid bacteria possess distinctive proportions of recognized transporter types (e.g., more porters specific for glycosides than reducing sugars). Some homologues of transporters identified had previously been identified only in Gram-negative bacteria or in eukaryotes. Our studies

  9. Transport Capabilities of Eleven Gram-positive Bacteria: Comparative Genomic Analyses

    PubMed Central

    Lorca, Graciela L.; Barabote, Ravi D.; Zlotopolski, Vladimir; Tran, Can; Winnen, Brit; Hvorup, Rikki N.; Stonestrom, Aaron J.; Nguyen, Elizabeth; Huang, Li-Wen; Kim, David S.; Saier, Milton H.

    2007-01-01

    The genomes of eleven Gram-positive bacteria that are important for human health and the food industry, nine low G+C lactic acid bacteria and two high G+C Gram-positive organisms, were analyzed for their complement of genes encoding transport proteins. Thirteen to eighteen percent of their genes encode transport proteins, larger percentages than observed for most other bacteria. All of these bacteria possess channel proteins, some of which probably function to relieve osmotic stress. Amino acid uptake systems predominate over sugar and peptide cation symporters, and of the sugar uptake porters, those specific for oligosaccharides and glycosides often outnumber those for free sugars. About 10% of the total transport proteins are constituents of putative multidrug efflux pumps with Major Facilitator Superfamily (MFS)-type pumps (55%) being more prevalent than ATP-binding cassette (ABC)-type pumps (33%), which, however, usually greatly outnumber all other types. An exception to this generalization is Streptococcus thermophilus with 54% of its drug efflux pumps belonging to the ABC superfamily and 23% belonging each to the Multidrug/Oligosaccharide/Polysaccharide (MOP) superfamily and the MFS. These bacteria also display peptide efflux pumps that may function in intercellular signalling, and macromolecular efflux pumps, many of predictable specificities. Most of the bacteria analyzed have no pmf-coupled or transmembrane flow electron carriers. The one exception is Brevibacterium linens, which in addition to these carriers, also has transporters of several families not represented in the other ten bacteria examined. Comparisons with the genomes of organisms from other bacterial kingdoms revealed that lactic acid bacteria possess distinctive proportions of recognized transporter types (e.g., more porters specific for glycosides than reducing sugars). Some homologues of transporters identified had previously been identified only in Gram-negative bacteria or in eukaryotes

  10. Systematic Review of Membrane Components of Gram-Positive Bacteria Responsible as Pyrogens for Inducing Human Monocyte/Macrophage Cytokine Release

    PubMed Central

    Rockel, Christoph; Hartung, Thomas

    2012-01-01

    Fifty years after the elucidation of lipopolysaccharides (LPS, endotoxin) as the principal structure of Gram-negative bacteria activating the human immune system, its Gram-positive counterpart is still under debate. Pyrogen tests based on the human monocyte activation have been validated for LPS detection as an alternative to the rabbit test and, increasingly, the limulus amebocyte lysate test. For full replacement, international validations with non-endotoxin pyrogens are in preparation. Following evidence-based medicine approaches, a systematic review of existing evidence as to the structural nature of the Gram-positive pyrogen was undertaken. For the three major constituents suggested, i.e., peptidoglycan, lipoteichoic acids (LTA), and bacterial lipoproteins (LP), the questions to be answered and a search strategy for relevant literature was developed, starting in MedLine. The evaluation was based on the Koch–Dale criteria for a mediator of an effect. A total of 380 articles for peptidoglycan, 391 for LP, and 285 for LTA were retrieved of which 12, 8, and 24, respectively, fulfilled inclusion criteria. The compiled data suggest that for peptidoglycan two Koch–Dale criteria are fulfilled, four for LTA, and two for bacterial LP. In conclusion, based on the best currently available evidence, LTA is the only substance that fulfills all criteria. LTA has been isolated from a large number of bacteria, results in cytokine release patterns inducible also with synthetic LTA. Reduction in bacterial cytokine induction with an inhibitor for LTA was shown. However, this systematic review cannot exclude the possibility that other stimulatory compounds complement or substitute for LTA in being the counterpart to LPS in some Gram-positive bacteria. PMID:22529809

  11. Results of the surveillance of Tedizolid activity and resistance program: in vitro susceptibility of gram-positive pathogens collected in 2011 and 2012 from the United States and Europe.

    PubMed

    Sahm, Daniel F; Deane, Jennifer; Bien, Paul A; Locke, Jeffrey B; Zuill, Douglas E; Shaw, Karen J; Bartizal, Ken F

    2015-02-01

    The in vitro activity and spectrum of tedizolid and comparators were analyzed against 6884 Gram-positive clinical isolates collected from multiple US and European sites as part of the Surveillance of Tedizolid Activity and Resistance Program in 2011 and 2012. Organisms included 4499 Staphylococcus aureus, 537 coagulase-negative staphylococci (CoNS), 873 enterococci, and 975 β-hemolytic streptococci. The MIC values that inhibited 90% of the isolates within each group (MIC90) were 0.25 μg/mL for Staphylococcus epidermidis and β-hemolytic streptococci and 0.5 μg/mL for S. aureus, other CoNS, and enterococci. Of 16 isolates with elevated tedizolid or linezolid MIC values (intermediate or resistant isolates), 10 had mutations in the genes encoding 23S rRNA (primarily G2576T), 5 had mutations in the genes encoding ribosomal proteins L3 or L4, and 5 carried the cfr multidrug resistance gene. Overall, tedizolid showed excellent activity against Gram-positive bacteria and was at least 4-fold more potent than linezolid against wild-type and linezolid-resistant isolates. Given the low overall frequency of isolates that would be resistant to tedizolid at the proposed break point of 0.5 μg/mL (0.19%) and potent activity against contemporary US and European isolates, tedizolid has the potential to serve as a valuable therapeutic option in the treatment of infections caused by Gram-positive pathogens.

  12. Deoxyribonucleic Acid Base Composition and Biochemical Properties of Certain Coagulase-Negative Enterotoxigenic Cocci

    PubMed Central

    Lotter, Leonard P.; Genigeorgis, Constantin A.

    1975-01-01

    Eight coagulase-negative, enterotoxigenic strains of cocci and one weakly coagulase-positive strain isolated from a number of different sources, including cases of food poisoning incidents, were evaluated for their relationship to Staphylococcus aureus on the basis of deoxyribonucleic acid (DNA) buoyant density and physiological studies. One strain of cocci produced enterotoxins A and C, two strains produced types B and C, four strains produced only type C, and one strain only type D. The enterotoxin produced by one strain of cocci was serologically untypable. None of the test organisms produced detectable amounts of enterotoxin in broth cultures. The test strains of cocci exhibited the following profile: all produced catalase; all grew anaerobically and fermented glucose; five were sensitive to lysostaphin; the percentage of guanine plus cytosine content of their DNA varied from 32.7 to 37.6; five produced acid from mannitol both aerobically and anaerobically; two formed δ-hemolysin; five produced phosphatase and acetoin; and all produced heat-stable nuclease. None of the organisms exhibited typical characteristics of S. aureus, S. epidermidis, or S. saprophyticus. On the basis of the present data and data reported elsewhere, these organisms should be considered as variants or mutants of S. aureus. PMID:803812

  13. Deoxyribonucleic acid base composition and biochemical properties of certain coagulase-negative enterotoxigenic cocci.

    PubMed

    Lotter, L P; Genigeorgis, C A

    1975-02-01

    Eight coagulase-negative, enterotoxigenic strains of cocci and one weakly coagulase-positive strain isolated from a number of different sources, including cases of food poisoning incidents, were evaluated for their relationship to Staphylococcus aureus on the basis of deoxyribonucleic acid (DNA) buoyant density and physiological studies. One strain of cocci produced enterotoxins A and C, two strains produced types B and C, four strains produced only type C, and one strain only type D. The enterotoxin produced by one strain of cocci was serologically untypable. None of the test organisms produced detectable amounts of enterotoxin in broth cultures. The test strains of cocci exhibited the following profile: all produced catalase; all grew anaerobically and fermented glucse; five were sensitive to lysostaphin; the percentage of guanine plus cytosine content of their DNA varied from 32.7 to 37.6; five produced acid from mannitol both aerobically and anaerobically; two formed delta-hemolysin; five produced phosphatase and acetoin; and all produced heat-stable nuclease. None of the organisms exhibited typical characteristics of S. aureus, S. epidermidis, or S. saprophyticus. On the basis of the present data and data reported elsewhere, these organisms should be considered as variants or mutants of S. aureus.

  14. Multicenter Evaluation of the Vitek MS Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry System for Identification of Gram-Positive Aerobic Bacteria

    PubMed Central

    Burnham, Carey-Ann D.; Bythrow, Maureen; Garner, Omai B.; Ginocchio, Christine C.; Jennemann, Rebecca; Lewinski, Michael A.; Manji, Ryhana; Mochon, A. Brian; Procop, Gary W.; Richter, Sandra S.; Sercia, Linda; Westblade, Lars F.; Ferraro, Mary Jane; Branda, John A.

    2013-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting. PMID:23658261

  15. Multicenter evaluation of the Vitek MS matrix-assisted laser desorption ionization-time of flight mass spectrometry system for identification of Gram-positive aerobic bacteria.

    PubMed

    Rychert, Jenna; Burnham, Carey-Ann D; Bythrow, Maureen; Garner, Omai B; Ginocchio, Christine C; Jennemann, Rebecca; Lewinski, Michael A; Manji, Ryhana; Mochon, A Brian; Procop, Gary W; Richter, Sandra S; Sercia, Linda; Westblade, Lars F; Ferraro, Mary Jane; Branda, John A

    2013-07-01

    Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF) is gaining momentum as a tool for bacterial identification in the clinical microbiology laboratory. Compared with conventional methods, this technology can more readily and conveniently identify a wide range of organisms. Here, we report the findings from a multicenter study to evaluate the Vitek MS v2.0 system (bioMérieux, Inc.) for the identification of aerobic Gram-positive bacteria. A total of 1,146 unique isolates, representing 13 genera and 42 species, were analyzed, and results were compared to those obtained by nucleic acid sequence-based identification as the reference method. For 1,063 of 1,146 isolates (92.8%), the Vitek MS provided a single identification that was accurate to the species level. For an additional 31 isolates (2.7%), multiple possible identifications were provided, all correct at the genus level. Mixed-genus or single-choice incorrect identifications were provided for 18 isolates (1.6%). Although no identification was obtained for 33 isolates (2.9%), there was no specific bacterial species for which the Vitek MS consistently failed to provide identification. In a subset of 463 isolates representing commonly encountered important pathogens, 95% were accurately identified to the species level and there were no misidentifications. Also, in all but one instance, the Vitek MS correctly differentiated Streptococcus pneumoniae from other viridans group streptococci. The findings demonstrate that the Vitek MS system is highly accurate for the identification of Gram-positive aerobic bacteria in the clinical laboratory setting.

  16. Relative Contribution of the Cell Wall, Cytoplasmic Membrane, and Cytoplasm to the Gram-Positive Characteristic of Bacillus megaterium

    PubMed Central

    Bartholomew, J. W.; Cromwell, Thomas

    1965-01-01

    Bartholomew, J. W. (University of Southern California, Los Angeles), and Thomas Cromwell. Relative contribution of the cell wall, cytoplasmic membrane, and cytoplasm to the gram-positive characteristic of Bacillus megaterium. J. Bacteriol. 90:643–647. 1965.—A comparison of the roles of the cell wall, cytoplasmic membrane, and cytoplasmic components revealed that the intact cell wall was the dominant contributor to the gram-positive state. Protoplasts of Bacillus megaterium were confirmed as being gram-negative, as reported by Gerhardt et al. The “gram-positive protoplast” report of Amano et al. was shown to be a laboratory-produced artifact, resulting from the comparison of smears made from saline suspensions of Escherichia coli cells with smears made from formalin-sucrose suspensions of B. megaterium protoplasts. PMID:16562061

  17. Fate study of water-borne gram positive vegetative bacterial cells with Raman microscopy

    NASA Astrophysics Data System (ADS)

    Guicheteau, Jason; Tripathi, Ashish; Minter, Jennifer; Wilcox, Phillip; Christesen, Steven

    2010-04-01

    We present an initial bacterial fate study of Gram positive vegetative cells suspended in water and stored at ambient room temperature via Raman spectroscopy monitoring. Two types of cells were considered for this study: vegetative cells of Bacillus cereus, Bacillus thuringiensis which contain the polyhydroxybutyric acid (PHBA) as an energy storage compound and Bacillus subtlilis cells which do not. The cells were cultured specifically for this project. Immediately following the culturing phase, the bacteria were extracted, cleaned and at the onset of the study were suspended in de-ionized water and stored at room temperature. Aliquots of suspensions were deposited onto aluminum slides at different times and allowed to dry for Raman analysis. Spectra from multiple regions of each dried spot and each deposit time were acquired along with the bright-field and fluorescence images. Results were examined to investigate the effect of suspension time on the spectral signatures as well as the fate behavior of the three types of cells investigated. The cells were monitored daily for over a 14 period during which time the onset of starvation induced sporulation was observed.

  18. Economic impact and formulary positioning of linezolid: a new anti-Gram-positive antimicrobial.

    PubMed

    Nathwani, D

    2001-12-01

    Gram-positive bacteria have emerged as major causes of colonization and serious infection within the nosocomial and increasingly also within the community setting. These infections have significantly contributed to patient morbidity and mortality as well as prolongation of hospital stay, a key determinant of the cost of an episode of infection in hospital. In many countries globally, infections due to methicillin-resistant Staphylococcus aureus (MRSA) are providing the greatest burden of clinical infection, often occurring in vulnerable patients or "high risk" therapeutic settings. Combined with this scenario is the increasing requirement for health care organizations to provide cost-effective health care as well as care that is delivered on evidence-based practice delivered through formularies or guidelines. This article aims to: 1) summarize the key economic considerations pertinent to these multiresistant infections but with an emphasis on MRSA, 2) discuss the current therapeutic options of managing MRSA infections, and 3) discuss the formulary positioning of linezolid by means of outlining its core strengths, weaknesses and the opportunity it provides to hospital infection management.

  19. Bacterial glycobiology: rhamnose-containing cell wall polysaccharides in Gram-positive bacteria

    PubMed Central

    Mistou, Michel-Yves; Sutcliffe, Iain C.; van Sorge, Nina M.

    2016-01-01

    The composition of the Gram-positive cell wall is typically described as containing peptidoglycan, proteins and essential secondary cell wall structures called teichoic acids, which comprise approximately half of the cell wall mass. The cell walls of many species within the genera Streptococcus, Enterococcus and Lactococcus contain large amounts of the sugar rhamnose, which is incorporated in cell wall-anchored polysaccharides (CWP) that possibly function as homologues of well-studied wall teichoic acids (WTA). The presence and chemical structure of many rhamnose-containing cell wall polysaccharides (RhaCWP) has sometimes been known for decades. In contrast to WTA, insight into the biosynthesis and functional role of RhaCWP has been lacking. Recent studies in human streptococcal and enterococcal pathogens have highlighted critical roles for these complex polysaccharides in bacterial cell wall architecture and pathogenesis. In this review, we provide an overview of the RhaCWP with regards to their biosynthesis, genetics and biological function in species most relevant to human health. We also briefly discuss how increased knowledge in this field can provide interesting leads for new therapeutic compounds and improve biotechnological applications. PMID:26975195

  20. Population biology of Gram-positive pathogens: high-risk clones for dissemination of antibiotic resistance

    PubMed Central

    Willems, Rob J. L.; Hanage, William P; Bessen, Debra E.; Feil, Edward J.

    2011-01-01

    Infections caused by multi-resistant Gram positive bacteria represent a major health burden in the community as well as in hospitalized patients. Staphylococcus aureus, Enterococcus faecalis and Enterococcus faecium are well-known pathogens of hospitalized patients, frequently linked with resistance against multiple antibiotics, compromising effective therapy. Streptococcus pneumoniae and Streptococcus pyogenes are important pathogens in the community and S. aureus has recently emerged as an important community-acquired pathogen. Population genetic studies reveal that recombination prevails as a driving force of genetic diversity in E. faecium, E. faecalis, S. pneumoniae, and S. pyogenes and thus, these species are weakly clonal. Although recombination has a relatively modest role driving the genetic variation of the core genome of S. aureus, the horizontal acquistion of resistance and virulence genes plays a key role in the emergence of new clinically relevant clones in this species. In this review we discuss the population genetics of E. faecium, E. faecalis, S. pneumoniae, S. pyogenes, and S. aureus. Knowledge of the population structure of these pathogens is not only highly relevant for (molecular) epidemiological research but also for identifying the genetic variation that underlies changes in clinical behaviour, to improve our understanding of the pathogenic behaviour of particular clones and to identify novel targets for vaccines or immunotherapy. PMID:21658083

  1. In vitro reconstitution of peptidoglycan assembly from the Gram-positive pathogen Streptococcus pneumoniae.

    PubMed

    Zapun, André; Philippe, Jules; Abrahams, Katherine A; Signor, Luca; Roper, David I; Breukink, Eefjan; Vernet, Thierry

    2013-12-20

    Understanding the molecular basis of bacterial cell wall assembly is of paramount importance in addressing the threat of increasing antibiotic resistance worldwide. Streptococcus pneumoniae presents a particularly acute problem in this respect, as it is capable of rapid evolution by homologous recombination with related species. Resistant strains selected by treatment with β-lactams express variants of the target enzymes that do not recognize the drugs but retain their activity in cell wall building, despite the antibiotics being mimics of the natural substrate. Until now, the crucial transpeptidase activity that is inhibited by β-lactams was not amenable to in vitro investigation with enzymes from Gram-positive organisms, including streptococci, staphylococci, or enterococci pathogens. We report here for the first time the in vitro assembly of peptidoglycan using recombinant penicillin-binding proteins from pneumococcus and the precursor lipid II. The two required enzymatic activities, glycosyl transferase for elongating glycan chains and transpeptidase for cross-linking stem-peptides, were observed. Most importantly, the transpeptidase activity was dependent on the chemical nature of the stem-peptide. Amidation of the second residue glutamate into iso-glutamine by the recently discovered amido-transferase MurT/GatD is required for efficient cross-linking of the peptidoglycan.

  2. Antibacterial properties of biosurfactants against selected Gram-positive and -negative bacteria.

    PubMed

    Díaz De Rienzo, Mayri A; Stevenson, Paul; Marchant, Roger; Banat, Ibrahim M

    2016-01-01

    The antibacterial properties and ability to disrupt biofilms of biosurfactants (rhamnolipids, sophorolipids) and sodium dodecyl sulphate (SDS) in the presence and absence of selected organic acids were investigated. Pseudomonas aeruginosa PAO1 was inhibited by sophorolipids and SDS at concentrations >5% v/v, and the growth of Escherichia coli NCTC 10418 was also inhibited by sophorolipids and SDS at concentrations >5% and 0.1% v/v, respectively. Bacillus subtilis NCTC 10400 was inhibited by rhamnolipids, sophorolipids and SDS at concentrations >0.5% v/v of all three; the same effect was observed with Staphylococcus aureus ATCC 9144. The ability to attach to surfaces and biofilm formation of P. aeruginosa PAO1, E. coli NCTC 10418 and B. subtilis NCTC 10400 was inhibited by sophorolipids (1% v/v) in the presence of caprylic acid (0.8% v/v). In the case of S. aureus ATCC 9144, the best results were obtained using caprylic acid on its own. It was concluded that sophorolipids are promising compounds for the inhibition/disruption of biofilms formed by Gram-positive and Gram-negative microorganisms and this activity can be enhanced by the presence of booster compounds such as caprylic acid.

  3. Gram-positive bacterial cell envelopes: The impact on the activity of antimicrobial peptides.

    PubMed

    Malanovic, Nermina; Lohner, Karl

    2016-05-01

    A number of cationic antimicrobial peptides, effectors of innate immunity, are supposed to act at the cytoplasmic membrane leading to permeabilization and eventually membrane disruption. Thereby, interaction of antimicrobial peptides with anionic membrane phospholipids is considered to be a key factor in killing of bacteria. Recently, evidence was provided that killing takes place only when bacterial cell membranes are completely saturated with peptides. This adds to an ongoing debate, which role cell wall components such as peptidoglycan, lipoteichoic acid and lipopolysaccharide may play in the killing event, i.e. if they rather entrap or facilitate antimicrobial peptides access to the cytoplasmic membrane. Therefore, in this review we focused on the impact of Gram-positive cell wall components for the mode of action and activity of antimicrobial peptides as well as in innate immunity. This led us to conclude that interaction of antimicrobial peptides with peptidoglycan may not contribute to a reduction of their antimicrobial activity, whereas interaction with anionic lipoteichoic acids may reduce the local concentration of antimicrobial peptides on the cytoplasmic membrane necessary for sufficient destabilization of the membranes and bacterial killing. Further affinity studies of antimicrobial peptides toward the different cell wall as well as membrane components will be needed to address this problem on a quantitative level. This article is part of a Special Issue entitled: Antimicrobial peptides edited by Karl Lohner and Kai Hilpert.

  4. Combination of Pantothenamides with Vanin Inhibitors as a Novel Antibiotic Strategy against Gram-Positive Bacteria

    PubMed Central

    Jansen, Patrick A. M.; Hermkens, Pedro H. H.; Zeeuwen, Patrick L. J. M.; Botman, Peter N. M.; Blaauw, Richard H.; Burghout, Peter; van Galen, Peter M.; Mouton, Johan W.; Rutjes, Floris P. J. T.

    2013-01-01

    The emergence of resistance against current antibiotics calls for the development of new compounds to treat infectious diseases. Synthetic pantothenamides are pantothenate analogs that possess broad-spectrum antibacterial activity in vitro in minimal media. Pantothenamides were shown to be substrates of the bacterial coenzyme A (CoA) biosynthetic pathway, causing cellular CoA depletion and interference with fatty acid synthesis. In spite of their potential use and selectivity for bacterial metabolic routes, these compounds have never made it to the clinic. In the present study, we show that pantothenamides are not active as antibiotics in the presence of serum, and we found that they were hydrolyzed by ubiquitous pantetheinases of the vanin family. To address this further, we synthesized a series of pantetheinase inhibitors based on a pantothenate scaffold that inhibited serum pantetheinase activity in the nanomolar range. Mass spectrometric analysis showed that addition of these pantetheinase inhibitors prevented hydrolysis of pantothenamides by serum. We found that combinations of these novel pantetheinase inhibitors and prototypic pantothenamides like N5-Pan and N7-Pan exerted antimicrobial activity in vitro, particularly against Gram-positive bacteria (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, and Streptococcus pyogenes) even in the presence of serum. These results indicate that pantothenamides, when protected against degradation by host pantetheinases, are potentially useful antimicrobial agents. PMID:23877685

  5. Chitosan Augments Photodynamic Inactivation of Gram-Positive and Gram-Negative Bacteria▿†

    PubMed Central

    Tsai, Tsuimin; Chien, Hsiung-Fei; Wang, Tze-Hsien; Huang, Ching-Tsan; Ker, Yaw-Bee; Chen, Chin-Tin

    2011-01-01

    Antimicrobial photodynamic inactivation (PDI) was shown to be a promising treatment modality for microbial infections. This study explores the effect of chitosan, a polycationic biopolymer, in increasing the PDI efficacy against Gram-positive bacteria, including Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, and methicillin-resistant S. aureus (MRSA), as well as the Gram-negative bacteria Pseudomonas aeruginosa and Acinetobacter baumannii. Chitosan at <0.1% was included in the antibacterial process either by coincubation with hematoporphyrin (Hp) and subjection to light exposure to induce the PDI effect or by addition after PDI and further incubation for 30 min. Under conditions in which Hp-PDI killed the microbe on a 2- to 4-log scale, treatment with chitosan at concentrations of as low as 0.025% for a further 30 min completely eradicated the bacteria (which were originally at ∼108 CFU/ml). Similar results were also found with toluidine blue O (TBO)-mediated PDI in planktonic and biofilm cells. However, without PDI treatment, chitosan alone did not exert significant antimicrobial activity with 30 min of incubation, suggesting that the potentiated effect of chitosan worked after the bacterial damage induced by PDI. Further studies indicated that the potentiated PDI effect of chitosan was related to the level of PDI damage and the deacetylation level of the chitosan. These results indicate that the combination of PDI and chitosan is quite promising for eradicating microbial infections. PMID:21282440

  6. Sortases and the Art of Anchoring Proteins to the Envelopes of Gram-Positive Bacteria

    PubMed Central

    Marraffini, Luciano A.; DeDent, Andrea C.; Schneewind, Olaf

    2006-01-01

    The cell wall envelopes of gram-positive bacteria represent a surface organelle that not only functions as a cytoskeletal element but also promotes interactions between bacteria and their environment. Cell wall peptidoglycan is covalently and noncovalently decorated with teichoic acids, polysaccharides, and proteins. The sum of these molecular decorations provides bacterial envelopes with species- and strain-specific properties that are ultimately responsible for bacterial virulence, interactions with host immune systems, and the development of disease symptoms or successful outcomes of infections. Surface proteins typically carry two topogenic sequences, i.e., N-terminal signal peptides and C-terminal sorting signals. Sortases catalyze a transpeptidation reaction by first cleaving a surface protein substrate at the cell wall sorting signal. The resulting acyl enzyme intermediates between sortases and their substrates are then resolved by the nucleophilic attack of amino groups, typically provided by the cell wall cross bridges of peptidoglycan precursors. The surface protein linked to peptidoglycan is then incorporated into the envelope and displayed on the microbial surface. This review focuses on the mechanisms of surface protein anchoring to the cell wall envelope by sortases and the role that these enzymes play in bacterial physiology and pathogenesis. PMID:16524923

  7. The Influence of Soft Layer Electrokinetics on Electroporation of Gram-positive Bacteria

    NASA Astrophysics Data System (ADS)

    Dingari, Naga Neehar; Moran, Jeffrey L.; Garcia, Paulo A.; Buie, Cullen R.

    2016-11-01

    Bacterial electroporation involves subjecting cells to intense ( 10 kV/cm) electric pulses, to open pores on the cell membrane for intracellular delivery of exogenous molecules. Its high efficiency in genetic transformation makes it an attractive tool for synthetic biology. While mammalian cell electroporation has received extensive theoretical and experimental investigation, bacterial electroporation has received markedly less attention. In this work, we develop a theoretical model of electroporation for gram-positive bacteria, taking into account the effect of the bacterial cell envelope on the cell's response to an electroporation pulse. We model the influence of the cell wall charge on the electrokinetic transport (and hence the pore properties) around the bacterial cell envelope using the Poisson-Nernst-Planck equations. Further, we account for the influence of the cell wall's mechanical elasticity on the pore radius evolution during electroporation, which is typically neglected in mammalian cell electroporation. This yields valuable information about favorable conditions for pore formation and will enable designing optimal platforms for bacteria electroporation.

  8. Effect of microwave irradiation on cellular disintegration of Gram positive and negative cells.

    PubMed

    Zhou, Bi Wen; Shin, Seung Gu; Hwang, KwangHyun; Ahn, Johng-Hwa; Hwang, Seokhwan

    2010-06-01

    This research investigated the effect of microwave irradiation (MWI) on cell disintegration in municipal secondary sludge (MSS). A representative MSS Gram-positive bacterium (Bacillus subtilis) and Gram-negative bacteria (Acinetobacter calcoaceticus and Pseudomonas aeruginosa) were pure cultured separately and treated using MWI. Compared to untreated controls, MWI significantly increased the soluble chemical oxygen demand (COD) (1.8-4.0-fold), soluble protein concentration (1.1-1.8-fold), and soluble carbohydrate concentration (3.2-14.1-fold), with greater increase in the Gram-negative bacteria. After MSS was MWI-treated with different irradiation times, from 0 to 9 min, soluble COD increased gradually from 0.14 to 2.38 g/L (i.e., 72-fold). Effective disintegration of Gram-negative cell walls and of MSS by MWI was confirmed by scanning electron microscopy. These findings suggest that MWI could be an effective pretreatment method for MSS that is dominated by Gram-negative microorganisms.

  9. Biofilms affecting progression of mild steel corrosion by Gram positive Bacillus sp.

    PubMed

    Lin, Johnson; Madida, Bafana B

    2015-10-01

    The biodeterioration of metals have detrimental effects on the environment with economic implications. The deterioration of metals is of great concern to industry. In this study, mild steel coupons which were immersed in a medium containing Gram-positive Bacillus spp. and different nutrient sources were compared with the control in sterile deionized water. The weight loss of the coupons in the presence of Bacillus spp. alone was lower than the control and was further reduced when additional carbon sources, especially fructose, were added. The level of metal corrosion was significantly increased in the presence of nitrate with or without bacteria. There was a significant strong correlation between the weight loss and biofilm level (r =  0.64; p < 0.05). The addition of nitrate and Bacillus spp. produced more biofilms on the coupons and resulted in greater weight loss compared to that with Bacillus spp. only under the same conditions. However, Bacillus spp. enriched with carbon sources formed less biofilms and results in lower weight loss compared to that with Bacillus spp. only. The production of biofilm by Bacillus spp. influences the level of metal corrosion under different environmental conditions, thereby, supporting the development of a preventive strategy against corrosion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. The RNPP family of quorum-sensing proteins in Gram-positive bacteria.

    PubMed

    Rocha-Estrada, Jorge; Aceves-Diez, Angel E; Guarneros, Gabriel; de la Torre, Mayra

    2010-07-01

    Quorum sensing is one of several mechanisms that bacterial cells use to interact with each other and coordinate certain physiological processes in response to cell density. This mechanism is mediated by extracellular signaling molecules; once a critical threshold concentration has been reached, a target sensor kinase or response regulator is activated (or repressed), facilitating the expression of quorum sensing-dependent genes. Gram-positive bacteria mostly use oligo-peptides as signaling molecules. These cells have a special kind of quorum-sensing systems in which the receptor protein interacts directly with its cognate signaling peptide. The receptors are either Rap phosphatases or transcriptional regulators and integrate the protein family RNPP, from Rap, Npr, PlcR, and PrgX. These quorum-sensing systems control several microbial processes, like sporulation, virulence, biofilm formation, conjugation, and production of extracellular enzymes. Insights of the mechanism of protein-signaling peptide binding as well as the molecular interaction among receptor protein, signaling peptide, and target DNA have changed some earlier perceptions. In spite of the increased knowledge and the potential biotechnological applications of these quorum-sensing systems, few examples on engineering for biotechnological applications have been published. Real applications will arise only when researchers working in applied microbiology and biotechnology are aware of the importance of quorum-sensing systems for health and bioprocess applications.

  11. Quorum-sensing regulators in Gram-positive bacteria: 'cherchez le peptide'.

    PubMed

    Monnet, V; Gardan, R

    2015-07-01

    Gram-positive bacteria can regulate gene expression at the population level via a mechanism known as quorum sensing. Oligopeptides serve as the signaling molecules; they are secreted and then are either detected at the bacterial surface by two-component systems or reinternalized via an oligopeptide transport system. In the latter case, imported peptides interact with cognate regulators (phosphatases or transcriptional regulators) that modulate the expression of target genes. These regulators help control crucial functions such as virulence, persistence, conjugation and competence and have been reported in bacilli, enterococci and streptococci. They form the rapidly growing RRNPP group. In this issue of Molecular Microbiology, Hoover et al. (2015) highlight the group's importance: they have identified a new family of regulators, Tprs (Transcription factor regulated by a Phr peptide), which work with internalized Phr-like peptides. The mechanisms underlying the expression of the genes that encode these internalized peptides are poorly documented. However, Hoover et al. (2015) have provided a new insight: an environmental molecule, glucose, can inhibit expression of the Phr-like peptide gene via catabolic repression. This previously undescribed regulatory pathway, controlling the production of a bacteriocin, might influence Streptococcus pneumonia's fitness in the nasopharynx, where galactose is present. © 2015 John Wiley & Sons Ltd.

  12. The Clavibacter michiganensis subspecies: molecular investigation of gram-positive bacterial plant pathogens.

    PubMed

    Eichenlaub, Rudolf; Gartemann, Karl-Heinz

    2011-01-01

    Clavibacter michiganensis subspecies are actinomycete plant pathogens residing mainly in the xylem vessels that infect economically important host plants. In the Clavibacter subspecies michiganensis and sepedonicus, infecting tomato and potato, respectively, essential factors for disease induction are plasmid encoded and loss of the virulence plasmids converts these biotrophic pathogens into endophytes. The genes responsible for successful colonization of the host plant, including evasion/suppression of plant defense reactions, are chromosomally encoded. Several serine proteases seem to be involved in colonization. They are secreted by Clavibacter, but their targets remain unknown. A type 3 secretion system (T3SS) translocating effectors into the plant cells is absent in these gram-positive pathogens. With the development of the modern 'omics technologies for RNA and proteins based on the known genome sequences, a new phase in the investigation of the mechanisms of plant pathogenicity has begun to allow the genome-wide investigation of the Clavibacter-host interaction. Copyright © 2011 by Annual Reviews. All rights reserved.

  13. Stuck in the Middle: Fibronectin-Binding Proteins in Gram-Positive Bacteria

    PubMed Central

    Hymes, Jeffrey P.; Klaenhammer, Todd R.

    2016-01-01

    Fibronectin is a multidomain glycoprotein found ubiquitously in human body fluids and extracellular matrices of a variety of cell types from all human tissues and organs, including intestinal epithelial cells. Fibronectin plays a major role in the regulation of cell migration, tissue repair, and cell adhesion. Importantly, fibronectin also serves as a common target for bacterial adhesins in the gastrointestinal tract. Fibronectin-binding proteins (FnBPs) have been identified and characterized in a wide variety of host-associated bacteria. Single bacterial species can contain multiple, diverse FnBPs. In pathogens, some FnBPs contribute to virulence via host cell attachment, invasion, and interference with signaling pathways. Although FnBPs in commensal and probiotic strains are not sufficient to confer virulence, they are essential for attachment to their ecological niches. Here we describe the interaction between human fibronectin and bacterial adhesins by highlighting the FnBPs of Gram-positive pathogens and commensals. We provide an overview of the occurrence and diversity of FnBPs with a focus on the model pathogenic organisms in which FnBPs are most characterized. Continued investigation of FnBPs is needed to fully understand their divergence and specificity in both pathogens and commensals. PMID:27713740

  14. Stuck in the Middle: Fibronectin-Binding Proteins in Gram-Positive Bacteria.

    PubMed

    Hymes, Jeffrey P; Klaenhammer, Todd R

    2016-01-01

    Fibronectin is a multidomain glycoprotein found ubiquitously in human body fluids and extracellular matrices of a variety of cell types from all human tissues and organs, including intestinal epithelial cells. Fibronectin plays a major role in the regulation of cell migration, tissue repair, and cell adhesion. Importantly, fibronectin also serves as a common target for bacterial adhesins in the gastrointestinal tract. Fibronectin-binding proteins (FnBPs) have been identified and characterized in a wide variety of host-associated bacteria. Single bacterial species can contain multiple, diverse FnBPs. In pathogens, some FnBPs contribute to virulence via host cell attachment, invasion, and interference with signaling pathways. Although FnBPs in commensal and probiotic strains are not sufficient to confer virulence, they are essential for attachment to their ecological niches. Here we describe the interaction between human fibronectin and bacterial adhesins by highlighting the FnBPs of Gram-positive pathogens and commensals. We provide an overview of the occurrence and diversity of FnBPs with a focus on the model pathogenic organisms in which FnBPs are most characterized. Continued investigation of FnBPs is needed to fully understand their divergence and specificity in both pathogens and commensals.

  15. Inactivation of Gram-positive biofilms by low-temperature plasma jet at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Marchal, F.; Robert, H.; Merbahi, N.; Fontagné-Faucher, C.; Yousfi, M.; Romain, C. E.; Eichwald, O.; Rondel, C.; Gabriel, B.

    2012-08-01

    This work is devoted to the evaluation of the efficiency of a new low-temperature plasma jet driven in ambient air by a dc-corona discharge to inactivate adherent cells and biofilms of Gram-positive bacteria. The selected microorganisms were lactic acid bacteria, a Weissella confusa strain which has the particularity to excrete a polysaccharide polymer (dextran) when sucrose is present. Both adherent cells and biofilms were treated with the low-temperature plasma jet for different exposure times. The antimicrobial efficiency of the plasma was tested against adherent cells and 48 h-old biofilms grown with or without sucrose. Bacterial survival was estimated using both colony-forming unit counts and fluorescence-based assays for bacterial cell viability. The experiments show the ability of the low-temperature plasma jet at atmospheric pressure to inactivate the bacteria. An increased resistance of bacteria embedded within biofilms is clearly observed. The resistance is also significantly higher with biofilm in the presence of sucrose, which indicates that dextran could play a protective role.

  16. Anchoring of LPXTG-Like Proteins to the Gram-Positive Cell Wall Envelope.

    PubMed

    Siegel, Sara D; Reardon, Melissa E; Ton-That, Hung

    2016-04-21

    In Gram-positive bacteria, protein precursors with a signal peptide and a cell wall sorting signal (CWSS)-which begins with an LPXTG motif, followed by a hydrophobic domain and a tail of positively charged residues-are targeted to the cell envelope by a transpeptidase enzyme call sortase. Evolution and selective pressure gave rise to six classes of sortase, i.e., SrtA-F. Only class C sortases are capable of polymerizing substrates harboring the pilin motif and CWSS into protein polymers known as pili or fimbriae, whereas the others perform cell wall anchoring functions. Regardless of the products generated from these sortases, the basic principle of sortase-catalyzed transpeptidation is the same. It begins with the cleavage of the LPXTG motif, followed by the cross-linking of this cleaved product at the threonine residue to a nucleophile, i.e., an active amino group of the peptidoglycan stem peptide or the lysine residue of the pilin motif. This chapter will summarize the efforts to identify and characterize sortases and their associated pathways with emphasis on the cell wall anchoring function.

  17. Tribolium castaneum defensins are primarily active against Gram-positive bacteria.

    PubMed

    Tonk, Miray; Knorr, Eileen; Cabezas-Cruz, Alejandro; Valdés, James J; Kollewe, Christian; Vilcinskas, Andreas

    2015-11-01

    The red flour beetle Tribolium castaneum is a destructive insect pest of stored food and feed products, and a model organism for development, evolutionary biology and immunity. The insect innate immune system includes antimicrobial peptides (AMPs) with a wide spectrum of targets including viruses, bacteria, fungi and parasites. Defensins are an evolutionarily-conserved class of AMPs and a potential new source of antimicrobial agents. In this context, we report the antimicrobial activity, phylogenetic and structural properties of three T. castaneum defensins (Def1, Def2 and Def3) and their relevance in the immunity of T. castaneum against bacterial pathogens. All three recombinant defensins showed bactericidal activity against Micrococcus luteus and Bacillus thuringiensis serovar tolworthi, but only Def1 and Def2 showed a bacteriostatic effect against Staphylococcus epidermidis. None of the defensins showed activity against the Gram-negative bacteria Escherichia coli and Pseudomonas entomophila or against the yeast Saccharomyces cerevisiae. All three defensins were transcriptionally upregulated following a bacterial challenge, suggesting a key role in the immunity of T. castaneum against bacterial pathogens. Phylogenetic analysis showed that defensins from T. castaneum, mealworms, Udo longhorn beetle and houseflies cluster within a well-defined clade of insect defensins. We conclude that T. castaneum defensins are primarily active against Gram-positive bacteria and that other AMPs may play a more prominent role against Gram-negative species.

  18. Metabolic basis for the differential susceptibility of Gram-positive pathogens to fatty acid synthesis inhibitors

    PubMed Central

    Parsons, Joshua B.; Frank, Matthew W.; Subramanian, Chitra; Saenkham, Panatda; Rock, Charles O.

    2011-01-01

    The rationale for the pursuit of bacterial type 2 fatty acid synthesis (FASII) as a target for antibacterial drug discovery in Gram-positive organisms is being debated vigorously based on their ability to incorporate extracellular fatty acids. The regulation of FASII by extracellular fatty acids was examined in Staphylococcus aureus and Streptococcus pneumoniae, representing two important groups of pathogens. Both bacteria use the same enzymatic tool kit for the conversion of extracellular fatty acids to acyl-acyl carrier protein, elongation, and incorporation into phospholipids. Exogenous fatty acids completely replace the endogenous fatty acids in S. pneumoniae but support only 50% of phospholipid synthesis in S. aureus. Fatty acids overcame FASII inhibition in S. pneumoniae but not in S. aureus. Extracellular fatty acids strongly suppress malonyl-CoA levels in S. pneumoniae but not in S. aureus, showing a feedback regulatory system in S. pneumoniae that is absent in S. aureus. Fatty acids overcame either a biochemical or a genetic block at acetyl-CoA carboxylase (ACC) in S. aureus, confirming that regulation at the ACC step is the key difference between these two species. Bacteria that possess a stringent biochemical feedback inhibition of ACC and malonyl-CoA formation triggered by environmental fatty acids are able to circumvent FASII inhibition. However, if exogenous fatty acids do not suppress malonyl-CoA formation, FASII inhibitors remain effective in the presence of fatty acid supplements. PMID:21876172

  19. Effect of betamethasone in combination with antibiotics on gram positive and gram negative bacteria.

    PubMed

    Artini, M; Papa, R; Cellini, A; Tilotta, M; Barbato, G; Koverech, A; Selan, L

    2014-01-01

    Betamethasone is an anti-inflammatory steroid drug used in cases of anaphylactic and allergic reactions, of Alzheimer and Addison diseases and in soft tissue injuries. It modulates gene expression for anti-inflammatory activity suppressing the immune system response. This latter effect might decrease the effectiveness of immune system response against microbial infections. Corticosteroids, in fact, mask some symptoms of infection and during their use superimposed infections may occur. Thus, the use of glucocorticoids in patients with sepsis remains extremely controversial. In this study we analyzed the in vitro effect of a commercial formulation of betamethasone (Bentelan) on several Gram positive and Gram negative bacteria of clinical relevance. It was found to be an inhibitor of the growth of most of the strains examined. Also the effect of betamethasone in combination with some classes of antibiotics was evaluated. Antibiotic-steroid combination therapy is, in such cases, superior to antibiotic-alone treatment to impair bacterial growths. Such effect was essentially not at all observable on Staphylococcus aureus or Coagulase Negative Staphylococci (CoNS).

  20. Linezolid in late-chronic prosthetic joint infection caused by gram-positive bacteria.

    PubMed

    Cobo, Javier; Lora-Tamayo, Jaime; Euba, Gorane; Jover-Sáenz, Alfredo; Palomino, Julián; del Toro, Ma Dolores; Rodríguez-Pardo, Dolors; Riera, Melchor; Ariza, Javier

    2013-05-01

    Linezolid may be an interesting alternative for prosthetic joint infection (PJI) due to its bioavailability and its antimicrobial spectrum. However, experience in this setting is scarce. The aim of the study was to assess linezolid's clinical and microbiological efficacy, and also its tolerance. This was a prospective, multicenter, open-label, non-comparative study of 25 patients with late-chronic PJI caused by Gram-positive bacteria managed with a two-step exchange procedure plus 6 weeks of linezolid. Twenty-two (88%) patients tolerated linezolid without major adverse effects, although a global decrease in the platelet count was observed. Three patients were withdrawn because of major toxicity, which reversed after linezolid stoppage. Among patients who completed treatment, 19 (86%) demonstrated clinical and microbiological cure. Two patients presented with clinical and microbiological failure, and one showed clinical cure and microbiological failure. In conclusion, linezolid showed good results in chronic PJI managed with a two-step exchange procedure. Tolerance seems acceptable, though close surveillance is required.

  1. Gramicidin A Mutants with Antibiotic Activity against Both Gram-Positive and Gram-Negative Bacteria.

    PubMed

    Zerfas, Breanna L; Joo, Yechaan; Gao, Jianmin

    2016-03-17

    Antimicrobial peptides (AMPs) have shown potential as alternatives to traditional antibiotics for fighting infections caused by antibiotic-resistant bacteria. One promising example of this is gramicidin A (gA). In its wild-type sequence, gA is active by permeating the plasma membrane of Gram-positive bacteria. However, gA is toxic to human red blood cells at similar concentrations to those required for it to exert its antimicrobial effects. Installing cationic side chains into gA has been shown to lower its hemolytic activity while maintaining the antimicrobial potency. In this study, we present the synthesis and the antibiotic activity of a new series of gA mutants that display cationic side chains. Specifically, by synthesizing alkylated lysine derivatives through reductive amination, we were able to create a broad selection of structures with varied activities towards Staphylococcus aureus and methicillin-resistant S. aureus (MRSA). Importantly, some of the new mutants were observed to have an unprecedented activity towards important Gram-negative pathogens, including Escherichia coli, Klebsiella pneumoniae and Psuedomonas aeruginosa. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Water-soluble pleuromutilin derivative with excellent in vitro and in vivo antibacterial activity against gram-positive pathogens.

    PubMed

    Hirokawa, Yoshimi; Kinoshita, Hironori; Tanaka, Tomoyuki; Nakata, Katsuhisa; Kitadai, Noriyuki; Fujimoto, Koichi; Kashimoto, Shigeki; Kojima, Tsuyoshi; Kato, Shiro

    2008-04-10

    Although earlier pleuromutilin analogues showed potent in vitro antibacterial activity against some Gram-positive pathogens, their in vivo efficacy was low because of insufficient pharmacokinetic properties. We designed novel thioether pleuromutilin derivatives having a purine ring as a polar and water solubilizing group and identified a promising pleuromutilin analogue 6 with good solubility in water ( approximately 50 mg/mL). Compound 6 exhibited excellent in vitro and in vivo antibacterial activity against some Gram-positive strains, including drug-resistant pathogens.

  3. Antioxidant activity via DPPH, gram-positive and gram-negative antimicrobial potential in edible mushrooms.

    PubMed

    Ahmad, Nisar; Mahmood, Fazal; Khalil, Shahid Akbar; Zamir, Roshan; Fazal, Hina; Abbasi, Bilal Haider

    2014-10-01

    Edible mushrooms (EMs) are nutritionally rich source of proteins and essential amino acids. In the present study, the antioxidant activity via 1,1-diphenyl-2-picrylhydrazyl (DPPH) and antimicrobial potential in EMs (Pleurotus ostreatus, Morchella esculenta, P. ostreatus (Black), P. ostreatus (Yellow) and Pleurotus sajor-caju) were investigated. The DPPH radical scavenging activity revealed that the significantly higher activity (66.47%) was observed in Morchella esculenta at a maximum concentration. Similarly, the dose-dependent concentrations (200, 400, 600, 800 and 1000 µg) were also used for other four EMs. Pleurotus ostreatus exhibited 36.13% activity, P. ostreatus (Black (B)) exhibited 30.64%, P. ostreatus (Yellow (Y)) exhibited 40.75% and Pleurotus sajor-caju exhibited 47.39% activity at higher concentrations. Furthermore, the antimicrobial potential were investigated for its toxicity against gram-negative bacterial strains (Escherichia coli, Pseudomonas aeroginosa, Salmonella typhi, Klebsiella pneumonia, Erwinia carotovora and Agrobacterium tumifaciens), gram-positive bacterial strains (Bacillus subtilis, Bacillus atrophaeus and Staphylococcus aureus) and a fungal strain (Candida albicans) in comparison with standard antibiotics. Antimicrobial screening revealed that the ethanol extract of P. ostreatus was active against all microorganism tested except E. coli. Maximum zone of inhibition (13 mm) was observed against fungus and A. tumifaciens. P. sajor-caju showed best activities (12.5 mm) against B. subtilis, B. atrophaeus and K. pneumonia. P. ostreatus (Y) showed best activities against P. aeroginosa (21.83 mm), B. atrophaeus (20 mm) and C. albicans (21 mm). P. ostreatus (B) exhibited best activities against C. albicans (16 mm) and slightly lower activities against all other microbes except S. typhi. M. esculenta possess maximum activities in terms of inhibition zone against all microorganisms tested except S. typhi.

  4. Effects of rhodomyrtone on Gram-positive bacterial tubulin homologue FtsZ

    PubMed Central

    Saeloh, Dennapa; Wenzel, Michaela; Rungrotmongkol, Thanyada; Hamoen, Leendert Willem

    2017-01-01

    Rhodomyrtone, a natural antimicrobial compound, displays potent activity against many Gram-positive pathogenic bacteria, comparable to last-defence antibiotics including vancomycin and daptomycin. Our previous studies pointed towards effects of rhodomyrtone on the bacterial membrane and cell wall. In addition, a recent molecular docking study suggested that the compound could competitively bind to the main bacterial cell division protein FtsZ. In this study, we applied a computational approach (in silico), in vitro, and in vivo experiments to investigate molecular interactions of rhodomyrtone with FtsZ. Using molecular simulation, FtsZ conformational changes were observed in both (S)- and (R)-rhodomyrtone binding states, compared with the three natural states of FtsZ (ligand-free, GDP-, and GTP-binding states). Calculations of free binding energy showed a higher affinity of FtsZ to (S)-rhodomyrtone (−35.92 ± 0.36 kcal mol−1) than the GDP substrate (−23.47 ± 0.25 kcal mol−1) while less affinity was observed in the case of (R)-rhodomyrtone (−18.11 ± 0.11 kcal mol−1). In vitro experiments further revealed that rhodomyrtone reduced FtsZ polymerization by 36% and inhibited GTPase activity by up to 45%. However, the compound had no effect on FtsZ localization in Bacillus subtilis at inhibitory concentrations and cells also did not elongate after treatment. Higher concentrations of rhodomyrtone did affect localization of FtsZ and also affected localization of its membrane anchor proteins FtsA and SepF, showing that the compound did not specifically inhibit FtsZ but rather impaired multiple divisome proteins. Furthermore, a number of cells adopted a bean-like shape suggesting that rhodomyrtone possibly possesses further targets involved in cell envelope synthesis and/or maintenance. PMID:28168121

  5. Improving linezolid use decreases the incidence of resistance among Gram-positive microorganisms.

    PubMed

    Ramírez, Elena; Gómez-Gil, Rosa; Borobia, Alberto M; Moreno, Francisco; Zegarra, Claudia; Muñoz, Raúl; Reutero, Zaida; de Montreuil, Carolina; González, Diana; Hernández, Sonsoles; Herrero, Alicia; Gutiérrez, Avelino; Frías, Jesús

    2013-02-01

    Surveillance studies have shown the emergence of infections with linezolid-resistant bacteria. The relationship between appropriate linezolid use and the spread of linezolid resistance among Gram-positive microorganisms in a single tertiary referral centre was evaluated. In an initial observational study, a prospective prescription-indication study was conducted on intensive care areas and haematology, neurosurgery, vascular surgery and nephrology wards during 2009. An intervention through follow-up feedback on audit results from May-June 2010 was then conducted. From July-December 2010, a second drug-use study of linezolid was conducted, with the same objectives and methodology. To assess the antimicrobial pressure of linezolid, an ecological study was conducted from 2006-2010 in the same hospital wards. Indications for linezolid in the initial study were considered suitable in 38.5% of cases, whilst in the second study the rate was 51.2% (33% increase). Linezolid consumption fell by 57% in the second half of 2010. A significant correlation was found between its inadequate use (DDD/1000 patient-days) and the incidence of linezolid-resistant strains/1000 patient-days (r=0.93; P=6.9e-024); 85% of the variability in the incidence of linezolid resistance was predicted by its inadequate use. Its partial correlations were significant for Enterococcus faecium (r=0.407; P=0.049), Staphylococcus epidermidis (r=0.874; P=2.3e-008) and Staphylococcus haemolyticus (r=0.406; P=0.049) but not Staphylococcus aureus (r=0.051; P=0.704). A relationship was found between appropriate linezolid use and the incidence of linezolid-resistant strains of E. faecium, S. epidermidis and S. haemolyticus.

  6. A Carbocyclic Curcumin Inhibits Proliferation of Gram-Positive Bacteria by Targeting FtsZ.

    PubMed

    Groundwater, Paul W; Narlawar, Rajeshwar; Liao, Vivian Wan Yu; Bhattacharya, Anusri; Srivastava, Shalini; Kunal, Kishore; Doddareddy, Munikumar; Oza, Pratik M; Mamidi, Ramesh; Marrs, Emma C L; Perry, John D; Hibbs, David E; Panda, Dulal

    2017-01-24

    Inhibition of FtsZ assembly has been found to stall bacterial cell division. Here, we report the identification of a potent carbocyclic curcumin analogue (2d) that inhibits Bacillus subtilis 168 cell proliferation by targeting the assembly of FtsZ. 2d also showed potent inhibitory activity (minimum inhibitory concentrations of 2-4 mg/L) against several clinically important species of Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus. In addition, 2d displayed a significantly reduced inhibitory effect on human cervical cancer cells in comparison to its effect on bacterial cells. Using live cell imaging of GFP-FtsZ by confocal microscopy, 2d was found to rapidly perturb the cytokinetic FtsZ rings in Bacillus subtilis cells. The immunofluorescence imaging of FtsZ also showed that 2d destroyed the Z-ring in bacteria within 5 min. Prolonged treatment with 2d produced filamentous bacteria, but 2d had no detectable effect either on the nucleoids or on the membrane potential of bacteria. 2d inhibited FtsZ assembly in vitro, whereas it had minimal effects on tubulin assembly. Interestingly, 2d strongly enhanced the GTPase activity of FtsZ and reduced the GTPase activity of tubulin. Furthermore, 2d bound to purified FtsZ with a dissociation constant of 4.0 ± 1.1 μM, and the binding of 2d altered the secondary structures of FtsZ. The results together suggested that the non-natural curcumin analogue 2d possesses powerful antibacterial activity against important pathogenic bacteria, and the evidence indicates that 2d inhibits bacterial proliferation by targeting FtsZ.

  7. Influenza antigen-sparing by immune stimulation with Gram-positive enhancer matrix (GEM) particles.

    PubMed

    Saluja, V; Visser, M R; Ter Veer, W; van Roosmalen, M L; Leenhouts, K; Hinrichs, W L J; Huckriede, A; Frijlink, H W

    2010-11-23

    Gram-positive enhancer matrix (GEM) particles, produced from non-genetically modified Lactococcus lactis bacteria have an inherent immunostimulatory activity. It was investigated whether co-administration of GEM particles can reduce the amount of influenza subunit vaccine (HA) necessary to protect mice from viral infection. Decreasing HA amounts of 5, 1, 0.2 and 0.04μg admixed with GEM particles were tested in intramuscular immunizations. Combinations of GEM and seasonal HA (A/Wisconsin/67/2005 [H3N2]) induced significantly higher systemic and better Th1/Th2-type balanced immune responses than HA alone. Addition of GEM to 0.04μg HA resulted in similar HI titers as 1-5μg non-adjuvanted HA. To test the protective efficacy of the adjuvanted combination, mice were immunized with influenza subunit vaccine A/PR/8/34 (H1N1) and then challenged with live virus (A/PR/8/34). Mice immunized with 1μg HA+GEM showed undetectable virus titers in the lungs 5 days after challenge, whereas mice immunized with 1μg HA alone showed detectable levels of virus in the lungs. Interestingly, mice vaccinated with the 0.04μg HA+GEM vaccine demonstrated reduced lung virus titers and a reduction in weight that was similar as that in mice vaccinated with 1μg non-adjuvanted HA. These results indicate that the use of GEM as immunostimulant allows for a strong reduction in the antigen dose as compared to the benchmark vaccine by using GEM particles. Thus, addition of GEM can strongly potentiate immunogenicity of influenza subunit vaccine both quantitatively and qualitatively. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. The cholesterol-dependent cytolysin family of gram-positive bacterial toxins.

    PubMed

    Heuck, Alejandro P; Moe, Paul C; Johnson, Benjamin B

    2010-01-01

    The cholesterol-dependent cytolysins (CDCs) are a family of beta-barrel pore-forming toxins secreted by Gram-positive bacteria. These toxins are produced as water-soluble monomeric proteins that after binding to the target cell oligomerize on the membrane surface forming a ring-like pre-pore complex, and finally insert a large beta-barrel into the membrane (about 250 A in diameter). Formation of such a large transmembrane structure requires multiple and coordinated conformational changes. The presence of cholesterol in the target membrane is absolutely required for pore-formation, and therefore it was long thought that cholesterol was the cellular receptor for these toxins. However, not all the CDCs require cholesterol for binding. Intermedilysin, secreted by Streptoccocus intermedius only binds to membranes containing a protein receptor, but forms pores only if the membrane contains sufficient cholesterol. In contrast, perfringolysin O, secreted by Clostridium perfringens, only binds to membranes containing substantial amounts of cholesterol. The mechanisms by which cholesterol regulates the cytolytic activity of the CDCs are not understood at the molecular level. The C-terminus of perfringolysin O is involved in cholesterol recognition, and changes in the conformation of the loops located at the distal tip of this domain affect the toxin-membrane interactions. At the same time, the distribution of cholesterol in the membrane can modulate toxin binding. Recent studies support the concept that there is a dynamic interplay between the cholesterol-binding domain of the CDCs and the excess of cholesterol molecules in the target membrane.

  9. Gram-Positive Bacterial Infections: Research Priorities, Accomplishments, and Future Directions of the Antibacterial Resistance Leadership Group.

    PubMed

    Doernberg, Sarah B; Lodise, Thomas P; Thaden, Joshua T; Munita, Jose M; Cosgrove, Sara E; Arias, Cesar A; Boucher, Helen W; Corey, G Ralph; Lowy, Franklin D; Murray, Barbara; Miller, Loren G; Holland, Thomas L

    2017-03-15

    Antimicrobial resistance in gram-positive bacteria remains a challenge in infectious diseases. The mission of the Gram-Positive Committee of the Antibacterial Resistance Leadership Group (ARLG) is to advance knowledge in the prevention, management, and treatment of these challenging infections to improve patient outcomes. Our committee has prioritized projects involving methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) due to the scope of the medical threat posed by these pathogens. Approved ARLG projects involving gram-positive pathogens include (1) a pharmacokinetics/pharmacodynamics study to evaluate the impact of vancomycin dosing on patient outcome in MRSA bloodstream infection (BSI); (2) defining, testing, and validating innovative assessments of patient outcomes for clinical trials of MRSA-BSI; (3) testing new strategies for "step-down" antibiotic therapy for MRSA-BSI; (4) management of staphylococcal BSIs in neonatal intensive care units; and (5) defining the impact of VRE bacteremia and daptomycin susceptibility on patient outcomes. This article outlines accomplishments, priorities, and challenges for research of infections caused by gram-positive organisms.

  10. Trans-generational Immune Priming Protects the Eggs Only against Gram-Positive Bacteria in the Mealworm Beetle.

    PubMed

    Dubuffet, Aurore; Zanchi, Caroline; Boutet, Gwendoline; Moreau, Jérôme; Teixeira, Maria; Moret, Yannick

    2015-10-01

    In many vertebrates and invertebrates, offspring whose mothers have been exposed to pathogens can exhibit increased levels of immune activity and/or increased survival to infection. Such phenomena, called "Trans-generational immune priming" (TGIP) are expected to provide immune protection to the offspring. As the offspring and their mother may share the same environment, and consequently similar microbial threats, we expect the immune molecules present in the progeny to be specific to the microbes that immune challenged the mother. We provide evidence in the mealworm beetle Tenebrio molitor that the antimicrobial activity found in the eggs is only active against Gram-positive bacteria, even when females were exposed to Gram-negative bacteria or fungi. Fungi were weak inducers of TGIP while we obtained similar levels of anti-Gram-positive activity using different bacteria for the maternal challenge. Furthermore, we have identified an antibacterial peptide from the defensin family, the tenecin 1, which spectrum of activity is exclusively directed toward Gram-positive bacteria as potential contributor to this antimicrobial activity. We conclude that maternal transfer of antimicrobial activity in the eggs of T. molitor might have evolved from persistent Gram-positive bacterial pathogens between insect generations.

  11. Dustborne and airborne gram-positive and gram-negative bacteria in high versus low ERMI homes

    EPA Science Inventory

    The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified...

  12. Trans-generational Immune Priming Protects the Eggs Only against Gram-Positive Bacteria in the Mealworm Beetle

    PubMed Central

    Dubuffet, Aurore; Zanchi, Caroline; Boutet, Gwendoline; Moreau, Jérôme; Teixeira, Maria; Moret, Yannick

    2015-01-01

    In many vertebrates and invertebrates, offspring whose mothers have been exposed to pathogens can exhibit increased levels of immune activity and/or increased survival to infection. Such phenomena, called “Trans-generational immune priming” (TGIP) are expected to provide immune protection to the offspring. As the offspring and their mother may share the same environment, and consequently similar microbial threats, we expect the immune molecules present in the progeny to be specific to the microbes that immune challenged the mother. We provide evidence in the mealworm beetle Tenebrio molitor that the antimicrobial activity found in the eggs is only active against Gram-positive bacteria, even when females were exposed to Gram-negative bacteria or fungi. Fungi were weak inducers of TGIP while we obtained similar levels of anti-Gram-positive activity using different bacteria for the maternal challenge. Furthermore, we have identified an antibacterial peptide from the defensin family, the tenecin 1, which spectrum of activity is exclusively directed toward Gram-positive bacteria as potential contributor to this antimicrobial activity. We conclude that maternal transfer of antimicrobial activity in the eggs of T. molitor might have evolved from persistent Gram-positive bacterial pathogens between insect generations. PMID:26430786

  13. Opioid Exacerbation of Gram-positive sepsis, induced by Gut Microbial Modulation, is Rescued by IL-17A Neutralization

    PubMed Central

    Meng, Jingjing; Banerjee, Santanu; Li, Dan; Sindberg, Gregory M.; Wang, Fuyuan; Ma, Jing; Roy, Sabita

    2015-01-01

    Sepsis is the predominant cause of mortality in ICUs, and opioids are the preferred analgesic in this setting. However, the role of opioids in sepsis progression has not been well characterized. The present study demonstrated that morphine alone altered the gut microbiome and selectively induced the translocation of Gram-positive gut bacteria in mice. Using a murine model of poly-microbial sepsis, we further demonstrated that morphine treatment led to predominantly Gram-positive bacterial dissemination. Activation of TLR2 by disseminated Gram-positive bacteria induced sustained up-regulation of IL-17A and IL-6. We subsequently showed that overexpression of IL-17A compromised intestinal epithelial barrier function, sustained bacterial dissemination and elevated systemic inflammation. IL-17A neutralization protected barrier integrity and improved survival in morphine-treated animals. We further demonstrated that TLR2 expressed on both dendritic cells and T cells play essential roles in IL-17A production. Additionally, intestinal sections from sepsis patients on opioids exhibit similar disruption in gut epithelial integrity, thus establishing the clinical relevance of this study. This is the first study to provide a mechanistic insight into the opioid exacerbation of sepsis and show that neutralization of IL-17A might be an effective therapeutic strategy to manage Gram-positive sepsis in patients on an opioid regimen. PMID:26039416

  14. Dustborne and airborne gram-positive and gram-negative bacteria in high versus low ERMI homes

    EPA Science Inventory

    The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified...

  15. Prevention of gram-positive infections in peritoneal dialysis patients in Hong Kong: a cost-effectiveness analysis.

    PubMed

    Wong, Carlos; Luk, In-Wa; Ip, Margaret; You, Joyce H S

    2014-04-01

    Gram-positive bacteria are the major causative pathogens of peritonitis and exit site infection in patients undergoing peritoneal dialysis (PD). We investigated the cost-effectiveness of regular application of mupirocin at the exit site in PD recipients from the perspective of health care providers in Hong Kong. A decision tree was designed to simulate outcomes of incident PD patients with and without regular application of mupirocin over a 1-year period. Outcome measures included total direct medical costs, quality-adjusted life-years (QALYs) gained, and gram-positive infection-related mortality rate. Model inputs were derived from the literature. Sensitivity analyses evaluated the impact of uncertainty in all model variables. In a base case analysis, the mupirocin group had a higher expected QALY value (0.6496 vs 0.6456), a lower infection-related mortality rate (0.18% vs 1.64%), and a lower total cost per patient (US $258 vs $1661) compared with the control group. The rate of gram-positive peritonitis without mupirocin and the risk of gram-positive peritonitis with mupirocin were influential factors. In 10,000 Monte Carlo simulations, the mupirocin group had significantly lower associated costs, higher QALYs, and a lower mortality rate 99.9% of the time. Topical mupirocin appears to be a cost-effective preventive measure against gram-positive infection in incident patients undergoing PD. The cost-effectiveness of mupirocin is affected by the level of infection risk reduction and subject to resistance against mupirocin. Copyright © 2014 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Mosby, Inc. All rights reserved.

  16. Daptomycin: an evidence-based review of its role in the treatment of Gram-positive infections.

    PubMed

    Gonzalez-Ruiz, Armando; Seaton, R Andrew; Hamed, Kamal

    2016-01-01

    Infections caused by Gram-positive pathogens remain a major public health burden and are associated with high morbidity and mortality. Increasing rates of infection with Gram-positive bacteria and the emergence of resistance to commonly used antibiotics have led to the need for novel antibiotics. Daptomycin, a cyclic lipopeptide with rapid bactericidal activity against a wide range of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus, has been shown to be effective and has a good safety profile for the approved indications of complicated skin and soft tissue infections (4 mg/kg/day), right-sided infective endocarditis caused by S. aureus, and bacteremia associated with complicated skin and soft tissue infections or right-sided infective endocarditis (6 mg/kg/day). Based on its pharmacokinetic profile and concentration-dependent bactericidal activity, high-dose (>6 mg/kg/day) daptomycin is considered an important treatment option in the management of various difficult-to-treat Gram-positive infections. Although daptomycin resistance has been documented, it remains uncommon despite the increasing use of daptomycin. To enhance activity and to minimize resistance, daptomycin in combination with other antibiotics has also been explored and found to be beneficial in certain severe infections. The availability of daptomycin via a 2-minute intravenous bolus facilitates its outpatient administration, providing an opportunity to reduce risk of health care-associated infections, improve patient satisfaction, and minimize health care costs. Daptomycin, not currently approved for use in the pediatric population, has been shown to be widely used for treating Gram-positive infections in children.

  17. Daptomycin: an evidence-based review of its role in the treatment of Gram-positive infections

    PubMed Central

    Gonzalez-Ruiz, Armando; Seaton, R Andrew; Hamed, Kamal

    2016-01-01

    Infections caused by Gram-positive pathogens remain a major public health burden and are associated with high morbidity and mortality. Increasing rates of infection with Gram-positive bacteria and the emergence of resistance to commonly used antibiotics have led to the need for novel antibiotics. Daptomycin, a cyclic lipopeptide with rapid bactericidal activity against a wide range of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus, has been shown to be effective and has a good safety profile for the approved indications of complicated skin and soft tissue infections (4 mg/kg/day), right-sided infective endocarditis caused by S. aureus, and bacteremia associated with complicated skin and soft tissue infections or right-sided infective endocarditis (6 mg/kg/day). Based on its pharmacokinetic profile and concentration-dependent bactericidal activity, high-dose (>6 mg/kg/day) daptomycin is considered an important treatment option in the management of various difficult-to-treat Gram-positive infections. Although daptomycin resistance has been documented, it remains uncommon despite the increasing use of daptomycin. To enhance activity and to minimize resistance, daptomycin in combination with other antibiotics has also been explored and found to be beneficial in certain severe infections. The availability of daptomycin via a 2-minute intravenous bolus facilitates its outpatient administration, providing an opportunity to reduce risk of health care-associated infections, improve patient satisfaction, and minimize health care costs. Daptomycin, not currently approved for use in the pediatric population, has been shown to be widely used for treating Gram-positive infections in children. PMID:27143941

  18. Genome-wide gene order distances support clustering the gram-positive bacteria

    PubMed Central

    House, Christopher H.; Pellegrini, Matteo; Fitz-Gibbon, Sorel T.

    2015-01-01

    Initially using 143 genomes, we developed a method for calculating the pair-wise distance between prokaryotic genomes using a Monte Carlo method to estimate the conservation of gene order. The method was based on repeatedly selecting five or six non-adjacent random orthologs from each of two genomes and determining if the chosen orthologs were in the same order. The raw distances were then corrected for gene order convergence using an adaptation of the Jukes-Cantor model, as well as using the common distance correction D′ = −ln(1-D). First, we compared the distances found via the order of six orthologs to distances found based on ortholog gene content and small subunit rRNA sequences. The Jukes-Cantor gene order distances are reasonably well correlated with the divergence of rRNA (R2 = 0.24), especially at rRNA Jukes-Cantor distances of less than 0.2 (R2 = 0.52). Gene content is only weakly correlated with rRNA divergence (R2 = 0.04) over all distances, however, it is especially strongly correlated at rRNA Jukes-Cantor distances of less than 0.1 (R2 = 0.67). This initial work suggests that gene order may be useful in conjunction with other methods to help understand the relatedness of genomes. Using the gene order distances in 143 genomes, the relations of prokaryotes were studied using neighbor joining and agreement subtrees. We then repeated our study of the relations of prokaryotes using gene order in 172 complete genomes better representing a wider-diversity of prokaryotes. Consistently, our trees show the Actinobacteria as a sister group to the bulk of the Firmicutes. In fact, the robustness of gene order support was found to be considerably greater for uniting these two phyla than for uniting any of the proteobacterial classes together. The results are supportive of the idea that Actinobacteria and Firmicutes are closely related, which in turn implies a single origin for the gram-positive cell. PMID:25653643

  19. A new hybrid bacteriocin, Ent35–MccV, displays antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria

    PubMed Central

    Acuña, Leonardo; Picariello, Gianluca; Sesma, Fernando; Morero, Roberto D.; Bellomio, Augusto

    2012-01-01

    Bacteriocins and microcins are ribosomally synthesized antimicrobial peptides that are usually active against phylogenetically related bacteria. Thus, bacteriocins are active against Gram-positive while microcins are active against Gram-negative bacteria. The narrow spectrum of action generally displayed by bacteriocins from lactic acid bacteria represents an important limitation for the application of these peptides as clinical drugs or as food biopreservatives. The present study describes the design and expression of a novel recombinant hybrid peptide combining enterocin CRL35 and microcin V named Ent35–MccV. The chimerical bacteriocin displayed antimicrobial activity against enterohemorrhagic Escherichia coli and Listeria monocytogenes clinical isolates, among other pathogenic bacteria. Therefore, Ent35–MccV may find important applications in food or pharmaceutical industries. PMID:23650575

  20. A new hybrid bacteriocin, Ent35-MccV, displays antimicrobial activity against pathogenic Gram-positive and Gram-negative bacteria.

    PubMed

    Acuña, Leonardo; Picariello, Gianluca; Sesma, Fernando; Morero, Roberto D; Bellomio, Augusto

    2012-01-01

    Bacteriocins and microcins are ribosomally synthesized antimicrobial peptides that are usually active against phylogenetically related bacteria. Thus, bacteriocins are active against Gram-positive while microcins are active against Gram-negative bacteria. The narrow spectrum of action generally displayed by bacteriocins from lactic acid bacteria represents an important limitation for the application of these peptides as clinical drugs or as food biopreservatives. The present study describes the design and expression of a novel recombinant hybrid peptide combining enterocin CRL35 and microcin V named Ent35-MccV. The chimerical bacteriocin displayed antimicrobial activity against enterohemorrhagic Escherichia coli and Listeria monocytogenes clinical isolates, among other pathogenic bacteria. Therefore, Ent35-MccV may find important applications in food or pharmaceutical industries.

  1. In vitro activity of WIN 49375 compared with those of other antibiotics in isolates from cancer patients.

    PubMed Central

    Garcia, I; Bodey, G P; Fainstein, V; Ho, D H; LeBlanc, B

    1984-01-01

    The activity of WIN 49375 [6-fluoro-1, 4-dihydro-1-(methylamino)-7-(4-methyl-1-piperazinyl)-4-oxo-3- quinolinecarboxylic acid], a new synthetic quinolone, was tested in vitro against 587 clinical isolates. The MICs for 90% of isolates of Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae were 0.20, 1.56, and 0.39 microgram/ml, respectively. The MICs for 90% of isolates of Pseudomonas aeruginosa and Serratia marcescens were both 3.12 micrograms/ml. WIN 49375 was minimally active against gram-positive cocci. Its in vitro activity suggests that it may be useful for the treatment of gram-negative bacillary infections. PMID:6508271

  2. GIL16, a New Gram-Positive Tectiviral Phage Related to the Bacillus thuringiensis GIL01 and the Bacillus cereus pBClin15 Elements

    PubMed Central

    Verheust, Céline; Fornelos, Nadine; Mahillon, Jacques

    2005-01-01

    One of the most notable characteristics of Tectiviridae resides in their double-layer coats: the double-stranded DNA is located within a flexible lipoprotein vesicle covered by a rigid protein capsid. Despite their apparent rarity, tectiviruses have an extremely wide distribution compared to other phage groups. Members of this family have been found to infect gram-negative (PRD1 and relatives) as well as gram-positive (Bam35, GIL01, AP50, and φNS11) hosts. Several reports have shown that tectiviruses infecting gram-negative bacteria are closely related, whereas no information is currently available on the genetic relationship among those infecting gram-positive bacteria. The present study reports the sequence of GIL16, a new isolate originating from Bacillus thuringiensis, and a genetic comparison of this isolate with the tectiviral bacteriophages Bam35 and GIL01, which originated from B. thuringiensis serovars Alesti and Israelensis, respectively. In contrast to PRD1 and its relatives, these are temperate bacteriophages existing as autonomous linear prophages within the host cell. Mutations in a particular motif in both the GIL01 and GIL16 phages are also shown to correlate with a switch to the lytic cycle. Interestingly, both bacterial viruses displayed narrow, yet slightly different, host spectrums. We also explore the hypothesis that pBClin15, a linear plasmid hosted by the Bacillus cereus reference strain ATCC 14579, is also a prophage. Sequencing of its inverted repeats at both extremities and a comparison with GIL01 and GIL16 emphasize its relationship to the Tectiviridae. PMID:15743944

  3. Sulfur Metabolism Pathways in Sulfobacillus acidophilus TPY, A Gram-Positive Moderate Thermoacidophile from a Hydrothermal Vent.

    PubMed

    Guo, Wenbin; Zhang, Huijun; Zhou, Wengen; Wang, Yuguang; Zhou, Hongbo; Chen, Xinhua

    2016-01-01

    Sulfobacillus acidophilus TPY, isolated from a hydrothermal vent in the Pacific Ocean, is a moderately thermoacidophilic Gram-positive bacterium that can oxidize ferrous iron or sulfur compounds to obtain energy. In this study, comparative transcriptomic analyses of S. acidophilus TPY were performed under different redox conditions. Based on these results, pathways involved in sulfur metabolism were proposed. Additional evidence was obtained by analyzing mRNA abundance of selected genes involved in the sulfur metabolism of sulfur oxygenase reductase (SOR)-overexpressed S. acidophilus TPY recombinant under different redox conditions. Comparative transcriptomic analyses of S. acidophilus TPY cultured in the presence of ferrous sulfate (FeSO4) or elemental sulfur (S(0)) were employed to detect differentially transcribed genes and operons involved in sulfur metabolism. The mRNA abundances of genes involved in sulfur metabolism decreased in cultures containing elemental sulfur, as opposed to cultures in which FeSO4 was present where an increase in the expression of sulfur metabolism genes, particularly sulfite reductase (SiR) involved in the dissimilatory sulfate reduction, was observed. SOR, whose mRNA abundance increased in S(0) culture, may play an important role in the initial sulfur oxidation. In order to confirm the pathways, SOR overexpression in S. acidophilus TPY and subsequent mRNA abundance analysis of sulfur metabolism-related genes were carried out. Conjugation-based transformation of pTrc99A derived plasmid from heterotrophic E. coli to facultative autotrophic S. acidophilus TPY was developed in this study. Transconjugation between E. coli and S. acidophilus was performed on modified solid 2:2 medium at pH 4.8 and 37°C for 72 h. The SOR-overexpressed recombinant S. acidophilus TPY-SOR had a [Formula: see text]-accumulation increase, higher oxidation/ reduction potentials (ORPs) and lower pH compared with the wild type strain in the late growth stage of S

  4. Sulfur Metabolism Pathways in Sulfobacillus acidophilus TPY, A Gram-Positive Moderate Thermoacidophile from a Hydrothermal Vent

    PubMed Central

    Guo, Wenbin; Zhang, Huijun; Zhou, Wengen; Wang, Yuguang; Zhou, Hongbo; Chen, Xinhua

    2016-01-01

    Sulfobacillus acidophilus TPY, isolated from a hydrothermal vent in the Pacific Ocean, is a moderately thermoacidophilic Gram-positive bacterium that can oxidize ferrous iron or sulfur compounds to obtain energy. In this study, comparative transcriptomic analyses of S. acidophilus TPY were performed under different redox conditions. Based on these results, pathways involved in sulfur metabolism were proposed. Additional evidence was obtained by analyzing mRNA abundance of selected genes involved in the sulfur metabolism of sulfur oxygenase reductase (SOR)-overexpressed S. acidophilus TPY recombinant under different redox conditions. Comparative transcriptomic analyses of S. acidophilus TPY cultured in the presence of ferrous sulfate (FeSO4) or elemental sulfur (S0) were employed to detect differentially transcribed genes and operons involved in sulfur metabolism. The mRNA abundances of genes involved in sulfur metabolism decreased in cultures containing elemental sulfur, as opposed to cultures in which FeSO4 was present where an increase in the expression of sulfur metabolism genes, particularly sulfite reductase (SiR) involved in the dissimilatory sulfate reduction, was observed. SOR, whose mRNA abundance increased in S0 culture, may play an important role in the initial sulfur oxidation. In order to confirm the pathways, SOR overexpression in S. acidophilus TPY and subsequent mRNA abundance analysis of sulfur metabolism-related genes were carried out. Conjugation-based transformation of pTrc99A derived plasmid from heterotrophic E. coli to facultative autotrophic S. acidophilus TPY was developed in this study. Transconjugation between E. coli and S. acidophilus was performed on modified solid 2:2 medium at pH 4.8 and 37°C for 72 h. The SOR-overexpressed recombinant S. acidophilus TPY-SOR had a SO42−-accumulation increase, higher oxidation/ reduction potentials (ORPs) and lower pH compared with the wild type strain in the late growth stage of S0 culture

  5. Analysis of an Effective Antibiotic (Chaetomacin) Isolated from a Thermophilic Bacillus sp. Against Olive Green Mold

    PubMed Central

    Tautorus, T. E.; Townsley, P. M.

    1984-01-01

    Successful methods to control the damaging weed mold Chaetomium olivaceum (olive green mold) in mushroom beds are not known. An effective antibiotic (named chaetomacin) against C. olivaceum was isolated from a thermophilic Bacillus sp. This compound was shown to be an extremely potent and stable antibiotic, effective over a wide range of both pH (2 to 10) and temperature (−15 to 150°C). Chaetomacin is soluble in most polar solvents and insoluble in nonpolar solvents. It is produced only at mesophilic temperatures and is also active against other Bacillus spp. and various eucaryotes, but it demonstrates no activity against gram-negative rods or gram-positive cocci. Final purification of chaetomacin was accomplished through thin-layer chromatography on silica gel analytical plates. Amino acid analysis revealed the antibiotic to be a peptide, acidic in nature. Examination of the literature reveals no other previously isolated antibiotics identical to chaetomacin. Images PMID:16346515

  6. [Characteristics of bacteria isolated from body surface of German cockroaches caught in hospitals].

    PubMed

    Czajka, Ewa; Pancer, Katarzyna; Kochman, Maria; Gliniewicz, Aleksandra; Sawicka, Bozena; Rabczenko, Daniel; Stypułkowska-Misiurewicz, Hanna

    2003-01-01

    The objective of the study was to identify bacterial flora from external parts of German cockroaches caught in hospitals. The susceptibility of the bacteria to the most important groups of antimicrobial agents was also examined. 80 strains of bacteria were isolated, among them 34 strains of Gram-positive cocci and 31 strains of Gram-negative rods. One of isolated strains of Citrobacter freundii and two strains of Serratia liquefaciens showed ESBL mechanism of resistance and extended level of AmpC--type beta-lactamases. Two Staphylococcus strains (S. epidermidis and S. equorum) were resistant to erythromycin and clindamycin (MLSB mechanism of resistance). Such strains, resistant to antibiotics and chemiotherapeutics may be reservoirs of resistance genes which can be transmitted into other bacteria. Presence of such pathogens on the body surface of German cockroaches, very mobile insects, might create conditions for easy dissemination of them in hospital environment.

  7. Pili in Gram-negative and Gram-positive bacteria - structure, assembly and their role in disease.

    PubMed

    Proft, T; Baker, E N

    2009-02-01

    Many bacterial species possess long filamentous structures known as pili or fimbriae extending from their surfaces. Despite the diversity in pilus structure and biogenesis, pili in Gram-negative bacteria are typically formed by non-covalent homopolymerization of major pilus subunit proteins (pilins), which generates the pilus shaft. Additional pilins may be added to the fiber and often function as host cell adhesins. Some pili are also involved in biofilm formation, phage transduction, DNA uptake and a special form of bacterial cell movement, known as 'twitching motility'. In contrast, the more recently discovered pili in Gram-positive bacteria are formed by covalent polymerization of pilin subunits in a process that requires a dedicated sortase enzyme. Minor pilins are added to the fiber and play a major role in host cell colonization.This review gives an overview of the structure, assembly and function of the best-characterized pili of both Gram-negative and Gram-positive bacteria.

  8. Synergy of nitric oxide and silver sulfadiazine against gram-negative, gram-positive, and antibiotic-resistant pathogens.

    PubMed

    Privett, Benjamin J; Deupree, Susan M; Backlund, Christopher J; Rao, Kavitha S; Johnson, C Bryce; Coneski, Peter N; Schoenfisch, Mark H

    2010-12-06

    The synergistic activity between nitric oxide (NO) released from diazeniumdiolate-modified proline (PROLI/NO) and silver(I) sulfadiazine (AgSD) was evaluated against Escherichia coli, Enterococcus faecalis, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis using a modified broth microdilution technique and a checkerboard-type assay. The combination of NO and AgSD was defined as synergistic when the fractional bactericidal concentration (FBC) was calculated to be <0.5. Gram-negative species were generally more susceptible to the individual antimicrobial agents than the Gram-positive bacteria, while Gram-positive bacteria were more susceptible to combination therapy. The in vitro synergistic activity of AgSD and NO observed against a range of pathogens strongly supports future investigation of this therapeutic combination, particularly for its potential use in the treatment of burns and chronic wounds.

  9. Evolution of sensitivity to fosfomycin in bacteria isolated in 1973, 1974 and 1975 in the Servicio de Microbiologia y Epidemiologia of the 'Clinica Puerta de Hierro', Madrid.

    PubMed

    Dámaso, D; Moreno-López, M; Martínez-Beltrán, J

    1977-01-01

    The bacteriostatic activity of fosfomycin was studied in vitro against 1,243 clinical isolations of gram-positive cocci and 4,086 isolations of gram-negative bacilli that were obtained in 1973, 1974 and in the period from January to May of 1975. MIC was determined by the agar diffusion method, quantifying it by means of the standard curve that was worked out with the strain of E. coli NCTC 10,418. A slight increase in resistance was observed in the gram-positive cocci: 64 mug/ml were inhibitory for 63% of the 249 isolations obtained in 1973, 59.1% of the 716 isolations obtained in 1974, and 57.5% of the 278 isolations from 1975. A slight loss of sensitivity was also observed in the gram-negative bacilli: the aforementioned concentration of fosfomycin inhibited 36% of the 742 isolations from 1973, 33.6% of the 2,387 isolations from 1974 and 32.6% of the 957 isolations from 1975. 933 g of this antibiotic were consumed in our hospital in 1973, 4,203 g in 1974 and 957 g in 1975. The consumption rate per patient per year was 0.15, 0.72 and 0.20 g, respectively. In conclusion, although no change was observed in the sensitivity of some bacterial strains to fosfomycin, the overall study indicates a slight decrease in the sensitivity, although it does not apparently have any relationship to the consumption of fosfomycin in our hospital.

  10. Dustborne and airborne Gram-positive and Gram-negative bacteria in high versus low ERMI homes.

    PubMed

    Adhikari, Atin; Kettleson, Eric M; Vesper, Stephen; Kumar, Sudhir; Popham, David L; Schaffer, Christopher; Indugula, Reshmi; Chatterjee, Kanistha; Allam, Karteek K; Grinshpun, Sergey A; Reponen, Tiina

    2014-06-01

    The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home's Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified into low (<5) and high (>5) ERMI groups based on the average ERMI values as well as 2011 ERMI values. Dust and air samples were collected from the homes in 2011 and all samples were analyzed for Gram-positive and Gram-negative bacteria using QPCR assays, endotoxin by the LAL assay, and N-acetyl-muramic acid using HPLC. In addition, air samples were analyzed for culturable bacteria. When average ERMI values were considered, the concentration and load of Gram-positive bacteria determined with QPCR in house dust, but not air, were significantly greater in high ERMI homes than in low ERMI homes. Furthermore, the concentration of endotoxin, but not muramic acid, in the dust was significantly greater in high ERMI than in low ERMI homes. In contrast, when ERMI values of 2011 were considered, Gram-negative bacteria determined with QPCR in air, endotoxin in air, and muramic acid in dust were significantly greater in high ERMI homes. The results suggest that both short-term and long-term mold contamination in homes could be linked with the bacterial concentrations in house dust, however, only the current mold status was associated with bacterial concentrations in air. Although correlations were found between endotoxin and Gram-negative bacteria as well as between muramic acid and Gram-positive bacteria in the entire data set, diverging associations were observed between the different measures of bacteria and the home moldiness. It is likely that concentrations of cells obtained by QPCR and concentrations of cell wall components are not equivalent and represent too broad categories to understand the bacterial composition and sources of the home microbiota.

  11. Relevance of GC content to the conservation of DNA polymerase III/mismatch repair system in Gram-positive bacteria

    PubMed Central

    Akashi, Motohiro; Yoshikawa, Hirofumi

    2013-01-01

    The mechanism of DNA replication is one of the driving forces of genome evolution. Bacterial DNA polymerase III, the primary complex of DNA replication, consists of PolC and DnaE. PolC is conserved in Gram-positive bacteria, especially in the Firmicutes with low GC content, whereas DnaE is widely conserved in most Gram-negative and Gram-positive bacteria. PolC contains two domains, the 3′-5′exonuclease domain and the polymerase domain, while DnaE only possesses the polymerase domain. Accordingly, DnaE does not have the proofreading function; in Escherichia coli, another enzyme DnaQ performs this function. In most bacteria, the fidelity of DNA replication is maintained by 3′-5′ exonuclease and a mismatch repair (MMR) system. However, we found that most Actinobacteria (a group of Gram-positive bacteria with high GC content) appear to have lost the MMR system and chromosomes may be replicated by DnaE-type DNA polymerase III with DnaQ-like 3′-5′ exonuclease. We tested the mutation bias of Bacillus subtilis, which belongs to the Firmicutes and found that the wild type strain is AT-biased while the mutS-deletant strain is remarkably GC-biased. If we presume that DnaE tends to make mistakes that increase GC content, these results can be explained by the mutS deletion (i.e., deletion of the MMR system). Thus, we propose that GC content is regulated by DNA polymerase and MMR system, and the absence of polC genes, which participate in the MMR system, may be the reason for the increase of GC content in Gram-positive bacteria such as Actinobacteria. PMID:24062730

  12. In vitro activity of Ozenoxacin against quinolone-susceptible and quinolone-resistant gram-positive bacteria.

    PubMed

    López, Y; Tato, M; Espinal, P; Garcia-Alonso, F; Gargallo-Viola, D; Cantón, R; Vila, J

    2013-12-01

    In vitro activity of ozenoxacin, a novel nonfluorinated topical (L. D. Saravolatz and J. Leggett, Clin. Infect. Dis. 37:1210-1215, 2003) quinolone, was compared with the activities of other quinolones against well-characterized quinolone-susceptible and quinolone-resistant Gram-positive bacteria. Ozenoxacin was 3-fold to 321-fold more active than other quinolones. Ozenoxacin could represent a first-in-class nonfluorinated quinolone for the topical treatment of a broad range of dermatological infections.

  13. Dustborne and Airborne Gram-Positive and Gram-Negative Bacteria in High versus Low ERMI Homes

    PubMed Central

    Adhikari, Atin; Kettleson, Eric M.; Vesper, Stephen; Kumar, Sudhir; Popham, David L.; Schaffer, Christopher; Indugula, Reshmi; Chatterjee, Kanistha; Allam, Karteek K.; Grinshpun, Sergey A.; Reponen, Tiina

    2014-01-01

    The study aimed at investigating Gram-positive and Gram-negative bacteria in moldy and non-moldy homes, as defined by the home’s Environmental Relative Moldiness Index (ERMI) value. The ERMI values were determined from floor dust samples in 2010 and 2011 and homes were classified into low (<5) and high (>5) ERMI groups based on the average ERMI values as well as 2011 ERMI values. Dust and air samples were collected from the homes in 2011 and all samples were analyzed for Gram-positive and Gram-negative bacteria using QPCR assays, endotoxin by the LAL assay, and N-acetyl-muramic acid using HPLC. In addition, air samples were analyzed for culturable bacteria. When average ERMI values were considered, the concentration and load of Gram-positive bacteria determined with QPCR in house dust, but not air, were significantly greater in high ERMI homes than in low ERMI homes. Furthermore, the concentration of endotoxin, but not muramic acid, in the dust was significantly greater in high ERMI than in low ERMI homes. In contrast, when ERMI values of 2011 were considered, Gram-negative bacteria determined with QPCR in air, endotoxin in air, and muramic acid in dust were significantly greater in high ERMI homes. The results suggest that both short-term and long-term mold contamination in homes could be linked with the bacterial concentrations in house dust, however, only the current mold status was associated with bacterial concentrations in air. Although correlations were found between endotoxin and Gram-negative bacteria as well as between muramic acid and Gram-positive bacteria in the entire data set, diverging associations were observed between the different measures of bacteria and the home moldiness. It is likely that concentrations of cells obtained by QPCR and concentrations of cell wall components are not equivalent and represent too broad categories to understand the bacterial composition and sources of the home microbiota. PMID:24642096

  14. Localization of Low Copy Number Plasmid pRC4 in Replicating Rod and Non-Replicating Cocci Cells of Rhodococcus erythropolis PR4

    PubMed Central

    Singhi, Divya; Jain, Aayushi; Srivastava, Preeti

    2016-01-01

    Rhodococcus are gram-positive bacteria, which can exist in two different shapes rod and cocci. A number of studies have been done in the past on replication and stability of small plasmids in this bacterium; however, there are no reports on spatial localization and segregation of these plasmids. In the present study, a low copy number plasmid pDS3 containing pRC4 replicon was visualized in growing cells of Rhodococcus erythropolis PR4 (NBRC100887) using P1 parS-ParB-GFP system. Cells were initially cocci and then became rod shaped in exponential phase. Cocci cells were found to be non-replicating as evident by the presence of single fluorescence focus corresponding to the plasmid and diffuse fluorescence of DnaB-GFP. Rod shaped cells contained plasmid either present as one fluorescent focus observed at the cell center or two foci localized at quarter positions. The results suggest that the plasmid is replicated at the cell center and then it goes to quarter position. In order to observe the localization of plasmid with respect to nucleoid, plasmid segregation was also studied in filaments where it was found to be replicated at the cell center in a nucleoid free region. To the best of our knowledge, this is the first report on segregation of small plasmids in R. erythropolis. PMID:27935968

  15. A Myeloid Hypoxia-inducible Factor 1α-Krüppel-like Factor 2 Pathway Regulates Gram-positive Endotoxin-mediated Sepsis*

    PubMed Central

    Mahabeleshwar, Ganapati H.; Qureshi, Muhammad Awais; Takami, Yoichi; Sharma, Nikunj; Lingrel, Jerry B.; Jain, Mukesh K.

    2012-01-01

    Although Gram-positive infections account for the majority of cases of sepsis, the molecular mechanisms underlying their effects remains poorly understood. We investigated how cell wall components of Gram-positive bacteria contribute to the development of sepsis. Experimental observations derived from cultured primary macrophages and the cell line indicate that Gram-positive bacterial endotoxins induce hypoxia-inducible factor 1α (HIF-1α) mRNA and protein expression. Inoculation of live or heat-inactivated Gram-positive bacteria with macrophages induced HIF-1 transcriptional activity in macrophages. Concordant with these results, myeloid deficiency of HIF-1α attenuated Gram-positive bacterial endotoxin-induced cellular motility and proinflammatory gene expression in macrophages. Conversely, Gram-positive bacteria and their endotoxins reduced expression of the myeloid anti-inflammatory transcription factor Krüppel-like transcription factor 2 (KLF2). Sustained expression of KLF2 reduced and deficiency of KLF2 enhanced Gram-positive endotoxins induced HIF-1α mRNA and protein expression in macrophages. More importantly, KLF2 attenuated Gram-positive endotoxins induced cellular motility and proinflammatory gene expression in myeloid cells. Consistent with these results, mice deficient in myeloid HIF-1α were protected from Gram-positive endotoxin-induced sepsis mortality and clinical symptomatology. By contrast, myeloid KLF2-deficient mice were susceptible to Gram-positive sepsis induced mortality and clinical symptoms. Collectively, these observations identify HIF-1α and KLF2 as critical regulators of Gram-positive endotoxin-mediated sepsis. PMID:22110137

  16. Lysis of gram-positive and gram-negative bacteria by antibacterial porous polymeric monolith formed in microfluidic biochips for sample preparation.

    PubMed

    Aly, Mohamed Aly Saad; Gauthier, Mario; Yeow, John

    2014-09-01

    Bacterial cell lysis is demonstrated using polymeric microfluidic biochips operating via a hybrid mechanical shearing/contact killing mechanism. These biochips are fabricated from a cross-linked poly(methyl methacrylate) (X-PMMA) substrate by well-controlled, high-throughput laser micromachining. The unreacted double bonds at the surface of X-PMMA provide covalent bonding for the formation of a porous polymeric monolith (PPM), thus contributing to the mechanical stability of the biochip and eliminating the need for surface treatment. The lysis efficiency of these biochips was tested for gram-positive (Enterococcus saccharolyticus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli and Pseudomonas fluorescens) and confirmed by off-chip PCR without further purification. The influence of the flow rate when pumping the bacterial suspension through the PPM, and of the hydrophobic-hydrophilic balance on the cell lysis efficiency was investigated at a cell concentration of 10(5) CFU/mL. It was shown that the contribution of contact killing to cell lysis was more important than that of mechanical shearing in the PPM. The biochip showed better lysis efficiency than the off-chip chemical, mechanical, and thermal lysis techniques used in this work. The biochip also acts as a filter that isolates cell debris and allows PCR-amplifiable DNA to pass through. The system performs more efficient lysis for gram-negative than for gram-positive bacteria. The biochip does not require chemical/enzymatic reagents, power consumption, or complicated design and fabrication processes, which makes it an attractive on-chip lysis device that can be used in sample preparation for genetics and point-of-care diagnostics. The biochips were reused for 20 lysis cycles without any evidence of physical damage to the PPM, significant performance degradation, or DNA carryover when they were back-flushed between cycles. The biochips efficiently lysed both gram-positive and gram

  17. Recent Advances in Multi-Drug Resistance (MDR) Efflux Pump Inhibitors of Gram-Positive Bacteria S. aureus

    PubMed Central

    Handzlik, Jadwiga; Matys, Anna; Kieć-Kononowicz, Katarzyna

    2013-01-01

    The paper focuses on recent achievements in the search for new chemical compounds able to inhibit multidrug resistance (MDR) mechanisms in Gram-positive pathogens. An analysis of the results of the search for new efflux pump inhibitors (EPIs) for Gram-positive bacteria, which have been performed over the last decade, indicates that almost all efforts are focused on the NorA (MFS) efflux pump in S. aureus. Considering the chemical structures of the NorA EPIs that have been identified, it can be observed that the most active agents belong to the families of compounds possessing conjugated double bonds, e.g., chalcones, piperine-like compounds, N-cinnamoylphenalkylamides or citral amide derivatives. Indole-, dihydronaphthyl-, 2-chloro-5-bromo-phenyl- or piperidine moieties seem to be profitable for the EPI properties, as well. These results, together with an increasing knowledge about a variety of efflux pumps that are involved in MDR of Gram-positive pathogens underline that further search for new EPIs should pay more attention to develop MDR efflux protein targets, including SMR, MATE, ABC or other members of the MFS family. PMID:27029290

  18. Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components

    NASA Technical Reports Server (NTRS)

    Gehron, M. J.; Davis, J. D.; Smith, G. A.; White, D. C.

    1984-01-01

    Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

  19. Probing interaction of gram-positive and gram-negative bacterial cells with ZnO nanorods.

    PubMed

    Jain, Aanchal; Bhargava, Richa; Poddar, Pankaj

    2013-04-01

    In the present work, the physiological effects of the ZnO nanorods on the Gram positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Aerobacter aerogenes) bacterial cells have been studied. The analysis of bacterial growth curves for various concentrations of ZnO nanorods indicates that Gram positive and Gram negative bacterial cells show inhibition at concentrations of ~64 and ~256 μg/mL respectively. The marked difference in susceptibility towards nanorods was also validated by spread plate and disk diffusion methods. In addition, the scanning electron micrographs show a clear damage to the cells via changed morphology of the cells from rod to coccoid etc. The confocal optical microscopy images of these cells also demonstrate the reduction in live cell count in the presence of ZnO nanorods. These, results clearly indicate that the antibacterial activity of ZnO nanorods is higher towards Gram positive bacterium than Gram negative bacterium which indicates that the structure of the cell wall might play a major role in the interaction with nanostructured materials and shows high sensitivity to the particle concentration.

  20. A novel beta-defensin structure: a potential strategy of big defensin for overcoming resistance by Gram-positive bacteria.

    PubMed

    Kouno, Takahide; Fujitani, Naoki; Mizuguchi, Mineyuki; Osaki, Tsukasa; Nishimura, Shin-ichiro; Kawabata, Shun-ichiro; Aizawa, Tomoyasu; Demura, Makoto; Nitta, Katsutoshi; Kawano, Keiichi

    2008-10-07

    Big defensin is a 79-residue peptide derived from hemocytes of the Japanese horseshoe crab. It has antimicrobial activities against Gram-positive and -negative bacteria. The amino acid sequence of big defensin can be divided into an N-terminal hydrophobic half and a C-terminal cationic half. Interestingly, the trypsin cleaves big defensin into two fragments, the N-terminal and C-terminal fragments, which are responsible for antimicrobial activity against Gram-positive and -negative bacteria, respectively. To explore the antimicrobial mechanism of big defensin, we determined the solution structure of mature big defensin and performed a titration experiment with DPC micelles. Big defensin has a novel defensin structure; the C-terminal domain adopts a beta-defensin structure, and the N-terminal domain forms a unique globular conformation. It is noteworthy that the hydrophobic N-terminal domain undergoes a conformational change in micelle solution, while the C-terminal domain remains unchanged. Here, we propose that the N-terminal domain achieves its antimicrobial activity in a novel fashion and explain that big defensin has developed a strategy different from those of other beta-defensins to suppress the growth of Gram-positive bacteria.

  1. Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components

    NASA Technical Reports Server (NTRS)

    Gehron, M. J.; Davis, J. D.; Smith, G. A.; White, D. C.

    1984-01-01

    Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

  2. A toll-like receptor 2-responsive lipid effector pathway protects mammals against skin infections with gram-positive bacteria.

    PubMed

    Georgel, Philippe; Crozat, Karine; Lauth, Xavier; Makrantonaki, Evgenia; Seltmann, Holger; Sovath, Sosathya; Hoebe, Kasper; Du, Xin; Rutschmann, Sophie; Jiang, Zhengfan; Bigby, Timothy; Nizet, Victor; Zouboulis, Christos C; Beutler, Bruce

    2005-08-01

    flake (flk), an N-ethyl-N-nitrosourea-induced recessive germ line mutation of C57BL/6 mice, impairs the clearance of skin infections by Streptococcus pyogenes and Staphylococcus aureus, gram-positive pathogens that elicit innate immune responses by activating Toll-like receptor 2 (TLR2). Positional cloning and sequencing revealed that flk is a novel allele of the stearoyl coenzyme A desaturase 1 gene (Scd1). flake homozygotes show reduced sebum production and are unable to synthesize the monounsaturated fatty acids (MUFA) palmitoleate (C(16:1)) and oleate (C(18:1)), both of which are bactericidal against gram-positive (but not gram-negative) organisms in vitro. However, intradermal MUFA administration to S. aureus-infected mice partially rescues the flake phenotype, which indicates that an additional component of the sebum may be required to improve bacterial clearance. In normal mice, transcription of Scd1-a gene with numerous NF-kappaB elements in its promoter--is strongly and specifically induced by TLR2 signaling. Similarly, the SCD1 gene is induced by TLR2 signaling in a human sebocyte cell line. These observations reveal the existence of a regulated, lipid-based antimicrobial effector pathway in mammals and suggest new approaches to the treatment or prevention of infections with gram-positive bacteria.

  3. A Toll-Like Receptor 2-Responsive Lipid Effector Pathway Protects Mammals against Skin Infections with Gram-Positive Bacteria

    PubMed Central

    Georgel, Philippe; Crozat, Karine; Lauth, Xavier; Makrantonaki, Evgenia; Seltmann, Holger; Sovath, Sosathya; Hoebe, Kasper; Du, Xin; Rutschmann, Sophie; Jiang, Zhengfan; Bigby, Timothy; Nizet, Victor; Zouboulis, Christos C.; Beutler, Bruce

    2005-01-01

    flake (flk), an N-ethyl-N-nitrosourea-induced recessive germ line mutation of C57BL/6 mice, impairs the clearance of skin infections by Streptococcus pyogenes and Staphylococcus aureus, gram-positive pathogens that elicit innate immune responses by activating Toll-like receptor 2 (TLR2) (K. Takeda and S. Akira, Cell. Microbiol. 5:143-153, 2003). Positional cloning and sequencing revealed that flk is a novel allele of the stearoyl coenzyme A desaturase 1 gene (Scd1). flake homozygotes show reduced sebum production and are unable to synthesize the monounsaturated fatty acids (MUFA) palmitoleate (C16:1) and oleate (C18:1), both of which are bactericidal against gram-positive (but not gram-negative) organisms in vitro. However, intradermal MUFA administration to S. aureus-infected mice partially rescues the flake phenotype, which indicates that an additional component of the sebum may be required to improve bacterial clearance. In normal mice, transcription of Scd1—a gene with numerous NF-κB elements in its promoter—is strongly and specifically induced by TLR2 signaling. Similarly, the SCD1 gene is induced by TLR2 signaling in a human sebocyte cell line. These observations reveal the existence of a regulated, lipid-based antimicrobial effector pathway in mammals and suggest new approaches to the treatment or prevention of infections with gram-positive bacteria. PMID:16040962

  4. Quorum sensing by peptide pheromones and two-component signal-transduction systems in Gram-positive bacteria.

    PubMed

    Kleerebezem, M; Quadri, L E; Kuipers, O P; de Vos, W M

    1997-06-01

    Cell-density-dependent gene expression appears to be widely spread in bacteria. This quorum-sensing phenomenon has been well established in Gram-negative bacteria, where N-acyl homoserine lactones are the diffusible communication molecules that modulate cell-density-dependent phenotypes. Similarly, a variety of processes are known to be regulated in a cell-density- or growth-phase-dependent manner in Gram-positive bacteria. Examples of such quorum-sensing modes in Gram-positive bacteria are the development of genetic competence in Bacillus subtilis and Streptococcus pneumoniae, the virulence response in Staphylococcus aureus, and the production of antimicrobial peptides by several species of Gram-positive bacteria including lactic acid bacteria. Cell-density-dependent regulatory modes in these systems appear to follow a common theme, in which the signal molecule is a post-translationally processed peptide that is secreted by a dedicated ATP-binding-cassette exporter. This secreted peptide pheromone functions as the input signal for a specific sensor component of a two-component signal-transduction system. Moreover, genetic linkage of the common elements involved results in autoregulation of peptide-pheromone production.

  5. Determination of the gram-positive bacterial content of soils and sediments by analysis of teichoic acid components.

    PubMed

    Gehron, M J; Davis, J D; Smith, G A; White, D C

    1984-01-01

    Many gram-positive bacteria form substituted polymers of glycerol and ribitol phosphate esters known as teichoic acids. Utilizing the relative specificity of cold concentrated hydrofluoric acid in the hydrolysis of polyphosphate esters it proved possible to quantitatively assay the teichoic acid-derived glycerol and ribitol from gram-positive bacteria added to various soils and sediments. The lipids are first removed from the soils or sediments with a one phase chloroform-methanol extraction and the lipid extracted residue is hydrolyzed with cold concentrated hydrofluoric acid. To achieve maximum recovery of the teichoic acid ribitol, a second acid hydrolysis of the aqueous extract is required. The glycerol and ribitol are then acetylated after neutralization and analyzed by capillary gas-liquid chromatography. This technique together with measures of the total phospholipid, the phospholipid fatty acid, the muramic acid and the hydroxy fatty acids of the lipopolysaccharide lipid A of the gram-negative bacteria makes it possible to describe the community structure environmental samples. The proportion of gram-positive bacteria measured as the teichoic acid glycerol and ribitol is higher in soils than in sediments and increases with depth in both.

  6. Gram-positive and gram-negative subcellular localization using rotation forest and physicochemical-based features

    PubMed Central

    2015-01-01

    Background The functioning of a protein relies on its location in the cell. Therefore, predicting protein subcellular localization is an important step towards protein function prediction. Recent studies have shown that relying on Gene Ontology (GO) for feature extraction can improve the prediction performance. However, for newly sequenced proteins, the GO is not available. Therefore, for these cases, the prediction performance of GO based methods degrade significantly. Results In this study, we develop a method to effectively employ physicochemical and evolutionary-based information in the protein sequence. To do this, we propose segmentation based feature extraction method to explore potential discriminatory information based on physicochemical properties of the amino acids to tackle Gram-positive and Gram-negative subcellular localization. We explore our proposed feature extraction techniques using 10 attributes that have been experimentally selected among a wide range of physicochemical attributes. Finally by applying the Rotation Forest classification technique to our extracted features, we enhance Gram-positive and Gram-negative subcellular localization accuracies up to 3.4% better than previous studies which used GO for feature extraction. Conclusion By proposing segmentation based feature extraction method to explore potential discriminatory information based on physicochemical properties of the amino acids as well as using Rotation Forest classification technique, we are able to enhance the Gram-positive and Gram-negative subcellular localization prediction accuracies, significantly. PMID:25734546

  7. Recent Advances in Multi-Drug Resistance (MDR) Efflux Pump Inhibitors of Gram-Positive Bacteria S. aureus.

    PubMed

    Handzlik, Jadwiga; Matys, Anna; Kieć-Kononowicz, Katarzyna

    2013-02-05

    The paper focuses on recent achievements in the search for new chemical compounds able to inhibit multidrug resistance (MDR) mechanisms in Gram-positive pathogens. An analysis of the results of the search for new efflux pump inhibitors (EPIs) for Gram-positive bacteria, which have been performed over the last decade, indicates that almost all efforts are focused on the NorA (MFS) efflux pump in S. aureus. Considering the chemical structures of the NorA EPIs that have been identified, it can be observed that the most active agents belong to the families of compounds possessing conjugated double bonds, e.g., chalcones, piperine-like compounds, N-cinnamoylphenalkylamides or citral amide derivatives. Indole-, dihydronaphthyl-, 2-chloro-5-bromo-phenyl- or piperidine moieties seem to be profitable for the EPI properties, as well. These results, together with an increasing knowledge about a variety of efflux pumps that are involved in MDR of Gram-positive pathogens underline that further search for new EPIs should pay more attention to develop MDR efflux protein targets, including SMR, MATE, ABC or other members of the MFS family.

  8. Acyl-sulfamates Target the Essential Glycerol-Phosphate Acyltransferase (PlsY) in Gram-Positive Bacteria

    PubMed Central

    Cherian, Philip; Yao, Jiangwei; Leonardi, Roberta; Maddox, Marcus M.; Luna, Vicki A.; Rock, Charles O.; Lee, Richard E.

    2012-01-01

    PlsY is the essential first step in membrane phospholipid synthesis of Gram-positive pathogens. PlsY catalyzes the transfer of the fatty acid from acyl-phosphate to the 1-position of glycerol-3-phosphate to form the first intermediate in membrane biogenesis. A series of non-metabolizable, acyl-sulfamate analogs of the acyl-phosphate PlsY substrate were prepared and evaluated as inhibitors of Staphylococcus aureus PlsY and for their Gram-positive antibacterial activities. From this series phenyl (8-phenyloctanoyl) sulfamate had the best overall profile, selectively inhibiting S. aureus phospholipid biosynthesis and causing the accumulation of both long-chain fatty acids and acyl-acyl carrier protein intermediates demonstrating that PlsY was the primary cellular target. Bacillus anthracis was unique in being more potently inhibited by long chain acyl-sulfamates than other bacterial species. However, it is shown that Bacillus anthracis PlsY is not more sensitive to the acyl-sulfamates than S. aureus PlsY. Metabolic profiling showed that B. anthracis growth inhibition by the acyl-sulfamates was not specific for lipid synthesis illustrating that the amphipathic acyl-sulfamates can also have off-target effects in Gram-positive bacteria. Nonetheless, this study further advances PlsY as a druggable target for the development of novel antibacterial therapeutics, through the discovery and validation of the probe compound phenyl (8-phenyloctanoyl) sulfamate as a S. aureus PlsY inhibitor. PMID:22795901

  9. Extracellular Vesicles Produced by the Gram-positive Bacterium Bacillus subtilis are Disrupted by the Lipopeptide Surfactin

    PubMed Central

    Brown, Lisa; Kessler, Anne; Cabezas-Sanchez, Pablo; Luque-Garcia, Jose L.; Casadevall, Arturo

    2014-01-01

    Summary Previously, extracellular vesicle production in Gram-positive bacteria was dismissed due to the absence of an outer membrane, where Gram-negative vesicles originate, and the difficulty in envisioning how such a process could occur through the cell wall. However, recent work has shown that Gram-positive bacteria produce extracellular vesicles and that the vesicles are biologically active. In this study, we show that Bacillus subtilis produces extracellular vesicles similar in size and morphology to other bacteria, characterized vesicles using a variety of techniques, provide evidence that these vesicles are actively produced by cells, show differences in vesicle production between strains, and identified a mechanism for such differences based on vesicle disruption. We found that in wild strains of B. subtilis, surfactin disrupted vesicles while in laboratory strains harboring a mutation in the gene sfp, vesicles accumulated in the culture supernatant. Surfactin not only lysed B. subtilis vesicles, but also vesicles from Bacillus anthracis, indicating a mechanism that crossed species boundaries. To our knowledge, this is the first time a gene and a mechanism has been identified in the active disruption of extracellular vesicles and subsequent release of vesicular cargo in Gram-positive bacteria. We also identify a new mechanism of action for surfactin. PMID:24826903

  10. Predominance of Gram-positive bacteria in house dust in the low-allergy risk Russian Karelia.

    PubMed

    Pakarinen, Jaakko; Hyvärinen, Anne; Salkinoja-Salonen, Mirja; Laitinen, Sirpa; Nevalainen, Aino; Mäkelä, Mika J; Haahtela, Tari; von Hertzen, Leena

    2008-12-01

    Simple living conditions and farming environment have been associated with reduced risk for allergic diseases such as atopy and asthma but the factors responsible for this effect remain unresolved. We examined the bacterial composition of house dusts obtained from Finnish and Russian Karelia, two adjacent areas with high and low occurrence of atopic diseases respectively. Two dust mixes, both composed of 10 randomly selected dust samples from 349 Finnish and 417 Russian Karelian households were studied for bacterial biomarkers (DNA, Limulus-active endotoxin, 3-OH fatty acids, muramic acid) and for 16S rRNA gene sequences. Overall, the DNA cloning revealed more taxons (94 different genera) of dustborne bacteria than seen in any previous study on residential environments. Majority (67%) of the bacterial DNA clones in house dust from the low-allergy Russian Kareliarepresented Gram-positive bacteria (Firmicutes and Actinobacteria), predominantly Staphylococcaceae and Corynebacteriaceae. Russian Karelian dust showed up to 20-fold higher contents of muramic acid (marker of Gram-positive bacteria) and a sevenfold higher number of clones of animal-associated species, whereas in Finnish Karelian dust Gram-negatives (mainly Proteobacteria) predominated. Clones of plant-associated bacterial species and of chloroplast, indicating plant biomass, were more numerous in Finnish than in Russian Karelian dust. In conclusion, this study revealed major disparities between Finnish and Russian house dusts. The higher bacterial content and the predominance of Gram-positive bacteria in Russian dust may have implications for occurrence of atopy.

  11. [Infections caused by multi-resistant Gram-positive bacteria (Staphylococcus aureus and Enterococcus spp.)].

    PubMed

    Cantón, Rafael; Ruiz-Garbajosa, Patricia

    2013-10-01

    Methicillin -resistant Staphylocccus aureus (MRSA) and multirresistant entorococci are still problematic in nosocomial infections and new challenges have emerged for their containment. MRSA has increased the multiresistant profile; it has been described vancomycin and linezolid resistant isolates and isolates with decreased daptomycin susceptibility. Moreover, new clones (ST398) have emerged, initially associated with piggeries, and new mec variants (mecC) with livestock origin that escape to the detection with current molecular methods based on mecA gene have been detected. In enterococci, linzeolid resistant isolates and isolates with deceased susceptibility to daptomycin have been described. Moreover, ampicillin resistant Enterococcus faecium due to β-lactamase production has been recently found in Europe. Control of MRSA isolates and multiresistant enteroccocci should combined antibiotic stewardship strategies and epidemiological measures, including detection of colonized patients in order to reduce colonization pressure and their transmission.

  12. Pharmacodynamic studies of trovafloxacin and grepafloxacin in vitro against Gram-positive and Gram-negative bacteria.

    PubMed

    Odenholt, I; Cars, T; Lowdin, E

    2000-07-01

    Grepafloxacin and trovafloxacin are two novel fluoroquinolones with extended Gram-positive bacterial spectra compared with older quinolones. The aim of the present study was to investigate the different pharmacodynamic parameters of grepafloxacin in comparison with those of trovafloxacin. The following studies were performed against various Gram-positive and Gram-negative bacteria: (i) determination of the rate and extent of killing at a concentration corresponding to the 1 h non-protein-bound human serum level following an oral dose of 800 mg grepafloxacin and 300 mg trovafloxacin; (ii) determination of the rate and extent of killing of the two quinolones at different concentrations; (iii) determination of the post-antibiotic effects (PAEs); (iv) determination of the post-antibiotic sub-MIC effects (PA SMEs); (iv) determination of the rate and extent of killing in an in vitro kinetic model. It was shown that both grepafloxacin and trovafloxacin exhibited concentration-dependent killing against both Gram-positive and Gram-negative bacteria. Grepafloxacin exhibited a slower bactericidal effect against all the Gram-positive strains investigated in comparison with trovafloxacin in spite of a similar C(max)/MIC in the static experiments and a similar AUC/MIC ratio in the kinetic experiments. No major differences in the extent and rate of killing were noted against the Gram-negative strains, which were killed almost completely after 3 h except for Pseudomonas aeruginosa. A PAE of both quinolones was noted for all strains investigated. Trovafloxacin induced longer PAEs against the Gram-positive strains but shorter PAEs in comparison with those of grepafloxacin against the Gram-negative strains. A prolonging of the PAEs was noted for all bacteria when exposed to sub-MICs in the post-antibiotic phase. With a similar AUC/MIC of 310 for the penicillin-sensitive strain of Streptococcus pneumoniae and 143 for the penicillin-resistant strain, the time for 99.9% eradication for

  13. Alternative fluorescent labeling strategies for characterizing gram-positive pathogenic bacteria: Flow cytometry supported counting, sorting, and proteome analysis of Staphylococcus aureus retrieved from infected host cells.

    PubMed

    Hildebrandt, Petra; Surmann, Kristin; Salazar, Manuela Gesell; Normann, Nicole; Völker, Uwe; Schmidt, Frank

    2016-10-01

    Staphylococcus aureus is a Gram-positive opportunistic pathogen that is able to cause a broad range of infectious diseases in humans. Furthermore, S. aureus is able to survive inside nonprofessional phagocytic host cell which serve as a niche for the pathogen to hide from the immune system and antibiotics therapies. Modern OMICs technologies provide valuable tools to investigate host-pathogen interactions upon internalization. However, these experiments are often hampered by limited capabilities to retrieve bacteria from such an experimental setting. Thus, the aim of this study was to develop a labeling strategy allowing fast detection and quantitation of S. aureus in cell lysates or infected cell lines by flow cytometry for subsequent proteome analyses. Therefore, S. aureus cells were labeled with the DNA stain SYTO(®) 9, or Vancomycin BODIPY(®) FL (VMB), a glycopeptide antibiotic binding to most Gram-positive bacteria which was conjugated to a fluorescent dye. Staining of S. aureus HG001 with SYTO 9 allowed counting of bacteria from pure cultures but not in cell lysates from infection experiments. In contrast, with VMB it was feasible to stain bacteria from pure cultures as well as from samples of infection experiments. VMB can also be applied for histocytochemistry analysis of formaldehyde fixed cell layers grown on coverslips. Proteome analyses of S. aureus labeled with VMB revealed that the labeling procedure provoked only minor changes on proteome level and allowed cell sorting and analysis of S. aureus from infection settings with sensitivity similar to continuous gfp expression. Furthermore, VMB labeling allowed precise counting of internalized bacteria and can be employed for downstream analyses, e.g., proteomics, of strains not easily amendable to genetic manipulation such as clinical isolates. © 2016 International Society for Advancement of Cytometry.

  14. Linezolid-resistant clinical isolates of enterococci and Staphylococcus cohnii from a multicentre study in China: molecular epidemiology and resistance mechanisms.

    PubMed

    Chen, Hongbin; Wu, Weiyuan; Ni, Ming; Liu, Yingmei; Zhang, Jixia; Xia, Fei; He, Wenqiang; Wang, Qi; Wang, Zhanwei; Cao, Bin; Wang, Hui

    2013-10-01

    Genetic characterisation of linezolid-resistant Gram-positive cocci in a multicentre study in China has not been reported previously. To study the mechanism underlying the resistance of linezolid-resistant isolates, nine Enterococcus faecalis, one Enterococcus faecium and three Staphylococcus cohnii isolates with various levels of resistance were collected from five hospitals across China in 2009-2012. The nine E. faecalis isolates were classified into seven sequence types, indicating that these linezolid-resistant E. faecalis isolates were polyclonal. Enterococci isolates had reduced susceptibility to linezolid (MICs of 4-8 mg/L) and had mutation of ribosomal protein L3, with three also having mutation of L4, but without the multidrug resistance gene cfr or the 23S rRNA mutation G2576T. The three S. cohnii isolates were highly resistant to linezolid (MICs of 64 mg/L to >256 mg/L), harboured the cfr gene and had the 23S rRNA mutation G2576T. Southern blotting indicated that the cfr gene of these three isolates resided on different plasmids (pHK01, pRM01 and pRA01). In plasmid pHK01, IS21-558 and the cfr gene were integrated into transposon Tn558. In plasmids pRM01 and pRA01, the cfr gene was flanked by two copies of an IS256-like insertion sequence, indicating that the transferable form of linezolid resistance is conferred by the cfr gene. In conclusion, the emergence of linezolid-resistant Gram-positive cocci in different regions of China is of concern. The cfr gene and the 23S rRNA mutation contribute to high-level linezolid resistance in S. cohnii, and the L3 and L4 mutations are associated with low-level linezolid resistance in enterococci.

  15. [Bacteria isolated from surgical infections and their susceptibility to antimicrobial agents--special reference to bacteria isolated between April 2007 and March 2008].

    PubMed

    Shinagawa, Nagao; Hasegawa, Masamitsu; Hirata, Koichi; Katsuramaki, Tadashi; Mizukuchi, Tohru; Ushijima, Yasuhide; Ushida, Tomohiro; Aikawa, Naoki; Yo, Kikuo; Yura, Jiro; Takeyama, Hiromitsu; Wakasugi, Takehiro; Taniguchi, Masaaki; Mizuno, Isamu; Mashita, Keiji; Ishikawa, Sw; Mizuno, Akira; Tsumura, Hiroaki; Yokoyama, Takashi; Moori, Noriaki; Sumita, Naoki; Kubo, Shoji; Lee, Shigeru; Oomura, Toru; Kobayashi, Yasuhito; Tsuji, Takeshi; Yamaue, Hiroki; Kawai, Manabu; Takesue, Yoshio; Tanaka, Noriaki; Kimura, Hideyuki; Iwagaki, Hiromi; Sueda, Taijiro; Hiyama, Eiso; Murakami, Yoshiaki; Ooge, Hiroki; Uemura, Kenichiro; Takeuchi, Hitoshi; Yasui, Yoshimasa; Yasunami, Yoichi; Ryu, Shinichiro

    2009-08-01

    Bacteria isolated from infections in abdominal surgery during the period from April 2007 to March 2008 were investigated in a multicenter study in Japan, and the following results were obtained. In this series, 707 strains including 24 strains of Candida spp. were isolated from 181 (79.0%) of 229 patients with surgical infections. Three hundred and ninety-five strains were isolated from primary infections, and 288 strains were isolated from postoperative infections. From primary infections, anaerobic Gram-negative bacteria were predominant, followed by aerobic Gram-negative bacteria, while from postoperative infections aerobic Gram-positive bacteria were predominant, followed by anaerobic Gram-negative bacteria. Among aerobic Gram-positive bacteria, the isolation rate of Enterococcus spp. was highest, followed by Streptococcus spp., and Staphylococcus spp. in this order, from primary infections, while Enterococcus spp. was highest, followed by Staphylococcus spp. from postoperative infections. Among aerobic Gram-negative bacteria, Escherichia coli was the most predominantly isolated from primary infections, followed by Klebsiella pneumoniae, Pseudomonas aeruginosa and Enterobacter cloacae, in this order, and from postoperative infections, P. aeruginosa was most predominantly isolated, followed by E. cloacae, E. coli and K. pneumoniae. Among anaerobic Gram-positive bacteria, the isolation rate of Parvimonas micra was the highest from primary infections, followed by Streptococcus constellatus and Gemella morbillorum, and from postoperative infections, Anaerococcus prevotii was most predominantly isolated. Among anaerobic Gram-negative bacteria, the isolation rate of both Bacteroides fragilis and Bilophila wadsworthia were the highest from primary infections, followed by Bacteroides thetaiotaomicron and Campylobacter gracilis, and from postoperative infections, B. thetaiotaomicron was most predominately isolated, followed by B. fragilis, Bacteroides caccae and B

  16. Staphylococcus aureus isolated from tonsillectomized adult patients with recurrent tonsillitis.

    PubMed

    Katkowska, Marta; Garbacz, Katarzyna; Stromkowski, Józef

    2017-01-01

    The aim of this study was to analyze the prevalence and antibiotic resistance of Staphylococcus aureus strains from 118 tonsillectomized adults due to recurrent tonsillitis (RT). The study included strains isolated from the tonsillar surface prior to tonsillectomy, recovered from the tonsillar core at the time of surgery, and from the posterior throat 2-4 weeks after the procedure. Susceptibility of isolates to 19 antibiotics was tested in line with the Clinical and Laboratory Standards Institute recommendations. Irrespective of the stage, the most commonly isolated bacteria were gram-positive cocci, and among them S. aureus. The tonsillar core was the most common site of S. aureus isolation (30.5%), followed by the tonsillar surface (10.8%) and the posterior pharynx (5.9%). This difference turned out to be statistically significant (p < 0.001). Beta-hemolytic streptococci, most often Streptococcus pyogenes (5.1%), were isolated from 2.5% to 10.2% of patients. Staphylococcal isolates were susceptible to most tested antibiotics (except from penicillin and ampicillin) and rarely showed methicillin resistance (n = 1). Staphylococcus aureus seems to be the most common pathogen isolated from patients tonsillectomized due to RT. Staphylococcal isolates associated with RT are present mostly within the tonsillar core and susceptible to most antibiotics. They are typically isolated from patients between 21 and 30 years of age. Tonsillectomy results in less frequent isolation of S. aureus strains.

  17. Antimicrobial activity of metal oxide nanoparticles against Gram-positive and Gram-negative bacteria: a comparative study

    PubMed Central

    Azam, Ameer; Ahmed, Arham S; Oves, Mohammad; Khan, Mohammad S; Habib, Sami S; Memic, Adnan

    2012-01-01

    Background Nanomaterials have unique properties compared to their bulk counterparts. For this reason, nanotechnology has attracted a great deal of attention from the scientific community. Metal oxide nanomaterials like ZnO and CuO have been used industrially for several purposes, including cosmetics, paints, plastics, and textiles. A common feature that these nanoparticles exhibit is their antimicrobial behavior against pathogenic bacteria. In this report, we demonstrate the antimicrobial activity of ZnO, CuO, and Fe2O3 nanoparticles against Gram-positive and Gram-negative bacteria. Methods and results Nanosized particles of three metal oxides (ZnO, CuO, and Fe2O3) were synthesized by a sol–gel combustion route and characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and transmission electron microscopy techniques. X-ray diffraction results confirmed the single-phase formation of all three nanomaterials. The particle sizes were observed to be 18, 22, and 28 nm for ZnO, CuO, and Fe2O3, respectively. We used these nanomaterials to evaluate their antibacterial activity against both Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus and Bacillus subtilis) bacteria. Conclusion Among the three metal oxide nanomaterials, ZnO showed greatest antimicrobial activity against both Gram-positive and Gram-negative bacteria used in this study. It was observed that ZnO nanoparticles have excellent bactericidal potential, while Fe2O3 nanoparticles exhibited the least bactericidal activity. The order of antibacterial activity was demonstrated to be the following: ZnO > CuO > Fe2O3. PMID:23233805

  18. A chromatographic approach to distinguish Gram-positive from Gram-negative bacteria using exogenous volatile organic compound metabolites.

    PubMed

    Ramírez-Guízar, Susana; Sykes, Hannah; Perry, John D; Schwalbe, Edward C; Stanforth, Stephen P; Perez-Perez, Ma Cristina I; Dean, John R

    2017-06-09

    This paper utilized L-alanine aminopeptidase activity as a useful approach to distinguish between Gram-negative and Gram-positive bacteria. This was done using two enzyme substrates, specifically 2-amino-N-phenylpropanamide and 2-amino-N-(4-methylphenyl)propanamide which liberated the volatile compounds aniline and p-toluidine, respectively. Two complementary analytical techniques have been used to identify and quantify the VOCs, specifically static headspace multicapillary column gas chromatography ion mobility spectrometry (SHS-MCC-GC-IMS) and headspace solid phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS). Superior limits of detection were obtained using HS-SPME-GC-MS, typically by a factor of x6 such that the LOD for aniline was 0.02μg/mL and 0.01μg/mL for p-toluidine. In addition, it was also possible to determine indole interference-free by HS-SPME-GC-MS at an LOD of 0.01μg/mL. The approach was applied to a range of selected bacteria: 15 Gram-negative and 7 Gram-positive bacteria. Use of pattern recognition, in the form of Principal Component Analysis, confirmed that it is possible to differentiate between Gram-positive and Gram-negative bacteria using the enzyme generated VOCs, aniline and p-toluidine. The exception was Stenotrophomonas maltophilia which showed negligible VOC concentrations for both aniline and p-toluidine, irrespective of the analytical techniques used and hence was not characteristic of the other Gram-negative bacteria investigated. The developed methodology has the potential to be applied for clinical and food applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. A Flexible Binding Site Architecture Provides New Insights into CcpA Global Regulation in Gram-Positive Bacteria

    PubMed Central

    Yang, Yunpeng; Zhang, Lu; Huang, He; Yang, Chen; Yang, Sheng

    2017-01-01

    ABSTRACT Catabolite control protein A (CcpA) is the master regulator in Gram-positive bacteria that mediates carbon catabolite repression (CCR) and carbon catabolite activation (CCA), two fundamental regulatory mechanisms that enable competitive advantages in carbon catabolism. It is generally regarded that CcpA exerts its regulatory role by binding to a typical 14- to 16-nucleotide (nt) consensus site that is called a catabolite response element (cre) within the target regions. However, here we report a previously unknown noncanonical flexible architecture of the CcpA-binding site in solventogenic clostridia, providing new mechanistic ins