This work was supported by an ANU Vice Chancellor’s travel grant. The funders had no role in study design, data collection and analysis, decision to
publish, or preparation of the manuscript

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Review of two decades of cholera diagnostics--how far have we really come?

Pathogenic non-O1/non-O139 Vibrio cholerae strains can cause sporadic outbreaks of cholera worldwide. In this study, multilocus sequence typing (MLST) of seven housekeeping genes was applied to 55 non-O1/non-O139 isolates from clinical and environmental sources. Data from five published O1 isolates and 17 genomes were also included, giving a total of 77 isolates available for analysis. There were 66 sequence types (STs), with the majority being unique, and only three clonal complexes. The V. cholerae strains can be divided into four subpopulations with evidence of recombination among the subpopulations. Subpopulations I and III contained predominantly clinical strains. PCR screening for virulence factors including Vibrio pathogenicity island (VPI), cholera toxin prophage (CTXΦ), type III secretion system (T3SS), and enterotoxin genes (rtxA and sto/stn) showed that combinations of these factors were present in the clinical isolates with 85.7% having rtxA, 51.4% T3SS, 31.4% VPI, 31.4% sto/stn (NAG-ST) and 11.4% CTXΦ. These factors were also present in environmental isolates but at a lower frequency. Five strains previously mis-identified as V. cholerae serogroups O114 to O117 were also analysed and formed a separate population with V. mimicus. The MLST scheme developed in this study provides a framework to identify sporadic cholera isolates by genetic identity.

Population Structure and Evolution of Non-O1/Non-O139 Vibrio cholerae by Multilocus Sequence Typing

Background
Cholera is still a significant public health issue in developing countries. The aetiological agent is Vibrio cholerae and only two serogroups, O1 and O139, are known to cause pandemic or epidemic cholera. In contrast, non-O1/non-O139 V. cholerae has only been reported to cause sporadic cholera-like illness and localised outbreaks. The aim of this study was to determine the genetic diversity of non-O1/non-O139 V. cholerae isolates from hospitalised diarrhoeal patients in Zhejiang Province, China.

/pdf/molecular-analysis-of-non-o1-non-o139-vibrio-cholerae-2njcq9rvby.pdf

Molecular analysis of non-O1/non-O139 Vibrio cholerae isolated from hospitalised patients in China

The objectives of this study were to detect the presence of Vibrio cholerae in tropical estuaries (Northeastern Brazil) and to search for virulence factors in the environmental isolates Water and sediment samples were inoculated onto a vibrio-selective medium (TCBS), and colonies with morphological resemblance to V cholerae were isolated The cultures were identified phenotypically using a dichotomous key based on biochemical characteristics The total DNA extracted was amplified by PCR to detect ompW and by multiplex PCR to detect the virulence genes ctx, tcp, zot and rfbO1 The results of the phenotypic and genotypic identification were compared Nine strains of V cholerae were identified phenotypically, five of which were confirmed by detection of the species-specific gene ompW The dichotomous key was efficient at differentiating environmental strains of V cholerae Strains of V cholerae were found in all four estuaries, but none possessed virulence genes

http://www.scielo.br/pdf/rimtsp/v56n5/0036-4665-rimtsp-56-05-427.pdf

DETECTION OF VIRULENCE GENES IN ENVIRONMENTAL STRAINS OF Vibrio cholerae FROM ESTUARIES IN NORTHEASTERN BRAZIL

Diarrhea continues to be one of the most common causes of morbidity and mortality among infants and children in developing countries. The aim of the present study was to evaluate the antibacterial and antioxidant activities of extracts and compounds from Ludwigia leptocarpa, a plant traditionally used for its vermifugal, anti-dysenteric, and antimicrobial properties. A methanol extract was prepared by maceration of the dried plant and this was successively extracted with ethyl acetate to obtain an EtOAc extract and with n-butanol to obtain an n-BuOH extract. Column chromatography of the EtOAc and n-BuOH extracts was followed by purification of different fractions, leading to the isolation of 10 known compounds. Structures of isolated compounds were assigned on the basis of spectral analysis and by comparison to structures of compounds described in the literature. Antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and gallic acid equivalent antioxidant capacity (GAEAC) assays. Antibacterial activity was assessed with the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) with respect to strains of a Gram-positive bacterium, Staphylococcus aureus (a major cause of community and hospital-associated infection), and Gram-negative multi-drug-resistant bacteria, Vibrio cholerae (a cause of cholera) and Shigella flexneri (a cause of shigellosis). All of the extracts showed different degrees of antioxidant and antibacterial activities. 2β-hydroxyoleanolic acid, (2R,3S,2''S)-3''',4',4''',5,5'',7,7''-heptahydroxy-3,8"-biflavanone, and luteolin-8-C-glucoside displayed the most potent antibacterial and antioxidant properties, and these properties were in some cases equal to or more potent than those of reference drugs. Overall, the present results show that L. leptocarpa has the potential to be a natural source of anti-diarrheal and antioxidant products, so further investigation is warranted.

Complex secondary metabolites from Ludwigia leptocarpa with potent antibacterial and antioxidant activities

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-0691.2009.02763.x

F.A.M.O. Cariri

Papers

Characterization of potentially virulent non-O1/non-O139 Vibrio cholerae strains isolated from human patients