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Journal ArticleDOI

Putative virulence traits and pathogenicity of Vibrio cholerae Non-O1, Non-O139 isolates from surface waters in Kolkata, India.

15 Sep 2008-Applied and Environmental Microbiology (American Society for Microbiology)-Vol. 74, Iss: 18, pp 5635-5644
TL;DR: Comparison of the counts of the colonized environmental and clinical strains in the mouse intestine showed that the organisms of both groups had similar colonizing efficiencies.
Abstract: Vibrio cholerae non-O1, non-O139 was isolated from natural surface waters from different sites sampled in diarrhea endemic zones in Kolkata, India. Twenty-one of these isolates were randomly selected and included in the characterization. The multiserogroup isolates were compared by their virulence traits with a group of clinical non-O1, non-O139 isolates from the same geographic area. Of the 21 environmental isolates, 6 and 14 strains belonged to Heiberg groups I and II, respectively. Three of the environmental isolates showed resistance to 2,2-diamine-6,7-diisopropylpteridine phosphate. All of the non-O1, non-O139 strains were positive for toxR, and except for one environmental isolate, none of them were positive for tcpA in the PCR assay. None of the isolates were positive for genes encoding cholera toxin (ctxA), heat-stable toxin (est), heat-labile toxin (elt), and Shiga toxin variants (stx) of Escherichia coli. Additionally, except for one environmental isolate (PC32), all were positive for the gene encoding El Tor hemolysin (hly). The culture supernatants of 86% (18 of 21) of the environmental isolates showed a distinct cytotoxic effect on HeLa cells, and some of these strains also produced cell-rounding factor. The lipase, protease, and cell-associated hemagglutination activities and serum resistance properties of the environmental and clinical isolates did not differ much. However, seven environmental isolates exhibited very high hemolytic activities (80 to 100%), while none of the clinical strains belonged to this group. The environmental isolates manifested three adherence patterns, namely, carpet-like, diffuse, and aggregative adherence, and the clinical isolates showed diffuse adherence on HeLa cells. Of the 11 environmental isolates tested for enteropathogenic potential, 8 (73%) induced positive fluid accumulation (≥100) in a mouse model, and the reactivities of these isolates were comparable to those of clinical strains of non-O1, non-O139 and toxigenic O139 V. cholerae. Comparison of the counts of the colonized environmental and clinical strains in the mouse intestine showed that the organisms of both groups had similar colonizing efficiencies. These findings indicate the presence of potentially pathogenic V. cholerae non-O1, non-O139 strains in surface waters of the studied sites in Kolkata.
Citations
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Journal ArticleDOI
TL;DR: In this paper, the authors used Bacteroidales host-specific quantitative PCR (qPCR) to quantify fecal bacteria in water and provide insights into contributing host fecal sources.
Abstract: The value of Bacteroidales genetic markers and fecal indicator bacteria (FIB) to predict the occurrence of waterborne pathogens was evaluated in ambient waters along the central California coast. Bacteroidales host-specific quantitative PCR (qPCR) was used to quantify fecal bacteria in water and provide insights into contributing host fecal sources. Over 140 surface water samples from 10 major rivers and estuaries within the Monterey Bay region were tested over 14 months with four Bacteroidales-specific assays (universal, human, dog, and cow), three FIB (total coliforms, fecal coliforms, and enterococci), two protozoal pathogens (Cryptosporidium and Giardia spp.), and four bacterial pathogens (Campylobacter spp., Escherichia coli O157:H7, Salmonella spp., and Vibrio spp.). Indicator and pathogen distribution was widespread, and detection was not highly seasonal. Vibrio cholerae was detected most frequently, followed by Giardia, Cryptosporidium, Salmonella, and Campylobacter spp. Bayesian conditional probability analysis was used to characterize the Bacteroidales performance assays, and the ratios of concentrations determined using host-specific and universal assays were used to show that fecal contamination from human sources was more common than livestock or dog sources in coastal study sites. Correlations were seen between some, but not all, indicator-pathogen combinations. The ability to predict pathogen occurrence in relation to indicator threshold cutoff levels was evaluated using a weighted measure that showed the universal Bacteroidales genetic marker to have a comparable or higher mean predictive potential than standard FIB. This predictive ability, in addition to the Bacteroidales assays providing information on contributing host fecal sources, supports using Bacteroidales assays in water quality monitoring programs.

89 citations


Cites background from "Putative virulence traits and patho..."

  • ...Different microbial species and strains may vary in virulence and ability to cause disease in human and animal hosts (3, 12, 13, 58), thus no conclusions should be drawn regarding their pathogenic potential without further characterization....

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Journal ArticleDOI
TL;DR: The results of the present study indicate that the purified flavonoids from G. glandulosum possess antimicrobial activities, which are in some cases equal to, or higher than those of ciprofloxacin used as reference antibiotic.
Abstract: The search for new antimicrobials should take into account drug resistance phenomenon. Medicinal plants are known as sources of potent antimicrobial compounds including flavonoids. The objective of this investigation was to evaluate the antimicrobial activities of flavonoid glycosides from Graptophyllum grandulosum, as well as to determine their mechanism of antibacterial action using lysis, leakage and osmotic stress assays. The plant extracts were prepared by maceration in organic solvents. Column chromatography of the n-butanol extract followed by purification of different fractions led to the isolation of five flavonoid glycosides. The antimicrobial activities of extracts/compounds were evaluated using the broth microdilution method. The bacteriolytic activity was evaluated using the time-kill kinetic method. The effect of extracts on the red blood cells and bacterial cell membrane was determined by spectrophotometric methods. Chrysoeriol-7-O-β-D-xyloside (1), luteolin-7-O-β-D-apiofuranosyl-(1 → 2)-β-D-xylopyranoside (2), chrysoeriol-7-O-β-D-apiofuranosyl-(1 → 2)-β-D-xylopyranoside (3), chrysoeriol-7-O-α-L-rhamnopyranosyl-(1 → 6)-β-D-(4"-hydrogeno sulfate) glucopyranoside (4) and isorhamnetin-3-O-α-L-rhamnopyranosyl-(1 → 6)-β-D-glucopyranoside (5) were isolated from G. grandulosum and showed different degrees of antimicrobial activities. Their antibacterial activities against multi-drug-resistant Vibrio cholerae strains were in some cases equal to, or higher than those of ciprofloxacin used as reference antibiotic. The antibacterial activities of flavonoid glycosides and chloramphenicol increased under osmotic stress (5% NaCl) whereas that of vancomycin decreased under this condition. V. cholerae suspension treated with flavonoid glycosides, showed a significant increase in the optical density at 260 nm, suggesting that nucleic acids were lost through a damaged cytoplasmic membrane. A decrease in the optical density of V. cholerae NB2 suspension treated with the isolated compounds was observed, indicating the lysis of bacterial cells. The tested samples were non-toxic to normal cells highlighting their good selectivity index. The results of the present study indicate that the purified flavonoids from G. glandulosum possess antimicrobial activities. Their mode of antibacterial activity is due to cell lysis and disruption of the cytoplasmic membrane upon membrane permeability.

79 citations


Cites background or methods from "Putative virulence traits and patho..."

  • ...However, the highest MIC value for compounds (64 μg/mL) was recorded with compound 3 against V. cholerae CO6, and with compounds 2 and 5 against C. albicans, while the highest MBC value of 128 μg/mL was obtained on V. cholerae CO6 with compound 3 and on C. albicans with compound 5....

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  • ...Hence, the EtOAc extract of G. glandulosum was highly active (MIC < 100 μg/mL) against V. cholerae SG24 (1),V. cholerae NB2,V. cholerae PC2 and S. aureus; significantly active (100 ≤MIC ≤512 μg/mL) against V. cholerae CO6 and C. neoformans; moderately active (512 <MIC ≤2048 μg/mL) on C. albicans....

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  • ...flexneri are particularly noteworthy since these strains were MDR clinical isolates which were resistant to commonly used drugs such as ampicillin, streptomycin, nalidixic acid, furazolidone and co-trimoxazole [16, 29, 30]....

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  • ...Table 1 further shows that under osmotic stress, the antibacterial activities of compounds 1, 2 and 4 against V. chorae SG24 (1), V. chorae CO6, V. chorae NB2 and V. chorae PC2 were higher than that of vancomycin....

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  • ...The microorganisms used in this study were consisted of five bacterial strains namely Staphylococcus aureus ATCC 25923, Vibrio cholerae NB2, PC2, SG24 (1) and CO6 [16]....

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Journal ArticleDOI
01 Jul 2011-Mbio
TL;DR: This study provides insight into in vivo mechanisms by which a novel TTSS contributes to diarrheal disease caused by nonpandemic strains of V. cholerae, and suggests that the T TSS-dependent virulence in non-O1,non-O139 V.cholerae represents a new type of diarrheagenic mechanism.
Abstract: Cholera is a severe diarrheal disease typically caused by O1 serogroup strains of Vibrio cholerae. The pathogenicity of all pandemic V. cholerae O1 strains relies on two critical virulence factors: cholera toxin, a potent enterotoxin, and toxin coregulated pilus (TCP), an intestinal colonization factor. However, certain non-O1, non-O139 V. cholerae strains, such as AM-19226, do not produce cholera toxin or TCP, yet they still cause severe diarrhea. The molecular basis for the pathogenicity of non-O1, non-O139 V. cholerae has not been extensively characterized, but many of these strains encode related type III secretion systems (TTSSs). Here, we used infant rabbits to assess the contribution of the TTSS to non-O1, non-O139 V. cholerae pathogenicity. We found that all animals infected with wild-type AM-19226 developed severe diarrhea even more rapidly than rabbits infected with V. cholerae O1. Unlike V. cholerae O1 strains, which do not damage the intestinal epithelium in rabbits or humans, AM-19226 caused marked disruptions of the epithelial surface in the rabbit small intestine. TTSS proved to be essential for AM-19226 virulence in infant rabbits; an AM-19226 derivative deficient for TTSS did not elicit diarrhea, colonize the intestine, or induce pathological changes in the intestine. Deletion of either one of the two previously identified or two newly identified AM-19226 TTSS effectors reduced but did not eliminate AM-19226 pathogenicity, suggesting that at least four effectors contribute to this strain's virulence. In aggregate, our results suggest that the TTSS-dependent virulence in non-O1, non-O139 V. cholerae represents a new type of diarrheagenic mechanism.

70 citations

Journal ArticleDOI
TL;DR: The impact that its environmental reservoirs have on disease transmission and the distinction between reservoirs of V. cholerae is discussed, as well as the interactions of the microorganism with other inhabitants of aquatic environments.
Abstract: Vibrio cholerae is widely known to be the etiological agent of the life-threatening diarrheal disease cholera. Cholera remains a major scourge in many developing countries, infecting hundreds of thousands every year. Remarkably, V. cholerae is a natural inhabitant of brackish riverine, estuarine, and coastal waters, and only a subset of strains are known to be pathogenic to humans. Recent studies have begun to uncover a very complex network of relationships between V. cholerae and other sea dwellers, and the mechanisms associated with the occurrence of seasonal epidemics in regions where cholera is endemic are beginning to be elucidated. Many of the factors required for the organism's survival and persistence in its natural environment have been revealed, as well as the ubiquitous presence of horizontal gene transfer in the emergence of pathogenic strains of V. cholerae. In this article, we will focus on the environmental stage of pathogenic V. cholerae and the interactions of the microorganism with other inhabitants of aquatic environments. We will discuss the impact that its environmental reservoirs have on disease transmission and the distinction between reservoirs of V. cholerae and the vectors that establish cholera as a zoonosis.

66 citations

References
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01 Jan 2001
TL;DR: The supplemental information presented in this document is intended for use with the antimicrobial susceptibility testing procedures published in the following Clinical and Laboratory Standards Institute (CLSI)–approved standards.
Abstract: The supplemental information presented in this document is intended for use with the antimicrobial susceptibility testing procedures published in the following Clinical and Laboratory Standards Institute (CLSI)–approved standards: M02-A12—Performance Standards for Antimicrobial Disk Susceptibility Tests; Approved Standard—Twelfth Edition; M07-A10—Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard—Tenth Edition; and M11-A8—Methods for Antimicrobial Susceptibility Testing of Anaerobic Bacteria; Approved Standard— Eighth Edition. The standards contain information about both disk (M02) and dilution (M07 and M11) test procedures for aerobic and anaerobic bacteria. Clinicians depend heavily on information from the microbiology laboratory for treatment of their seriously ill patients. The clinical importance of antimicrobial susceptibility test results demands that these tests be performed under optimal conditions and that laboratories have the capability to provide results for the newest antimicrobial agents. The tabular information presented here represents the most current information for drug selection, interpretation, and QC using the procedures standardized in the most current editions of M02, M07, and M11. Users should replace the tables published earlier with these new tables. (Changes in the tables since the previous edition appear in boldface type.) Clinical and Laboratory Standards Institute (CLSI). Performance Standards for Antimicrobial Susceptibility Testing. 26th ed. CLSI supplement M100S (ISBN 1-56238-923-8 [Print]; ISBN 1-56238924-6 [Electronic]). Clinical and Laboratory Standards Institute, 950 West Valley Road, Suite 2500, Wayne, Pennsylvania 19087 USA, 2016. The data in the interpretive tables in this supplement are valid only if the methodologies in M02-A12—Performance Standards for Antimicrobial Disk Susceptibility Tests; Approved Standard—Twelfth Edition; M07-A10—Methods for Dilution Antimicrobial Susceptibility Tests for Bacteria That Grow Aerobically; Approved Standard—Tenth Edition; and M11-A8—Methods for Antimicrobial Susceptibility Testing of Anaerobic Bacteria; Approved Standard— Eighth Edition are followed.

17,824 citations

Journal ArticleDOI
TL;DR: Recommendations of the National Committee for Clinical Laboratory Standards continue to be based on this publication; the “Kirby-Bauer” method is, among the many disk methods used in other countries, still the one that has been researched most thoroughly and updated continuously.
Abstract: In the words of the authors, the paper by A. W. Bauer et al., from the University of Washington in Seattle, on a standardized single-disk method for antibiotic susceptibility testing “. . . consolidate(s) and update(s) previous descriptions of the method and provide(s) a concise outline for its performance and interpretation.” Clinical microbiologists were relieved that finally a disk diffusion method had been standardized, could be used with ease, and provided reliable results as compared with minimum inhibitory concentration tests. The pivotal role of Hans Ericsson’s theoretical and practical studies (H. Ericsson and G. Svartz-Malmberg, Antibiot. Chemother. 6:41–74, 1959), as well as earlier reports by some of the authors of the publications cited, must be mentioned as a matter of fairness. Most of the recommendations given are still valid today even though some of the antimicrobial agents are obsolete, new ones have been added, some zone sizes had to be modified, and new media were designed for Haemophilus influenzae and Neisseria gonorrhoeae. Recommendations of the National Committee for Clinical Laboratory Standards continue to be based on this publication; the “Kirby-Bauer” method is, among the many disk methods used in other countries, still the one that has been researched most thoroughly and updated continuously. ALEXANDER VON GRAEVENITZ

16,916 citations

Journal ArticleDOI

1,387 citations


"Putative virulence traits and patho..." refers background or methods in this paper

  • ...cholerae gives negative reactions for D-sorbitol, L-rhamnose, melibiose, L-arabinose, and salicin fermentation (15)....

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  • ...positive reactions were identified by methods described previously (13, 15, 49)...

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  • ...cholerae is arginine dihydrolase negative and lysine and ornithine decarboxylase positive (15)....

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