Transmission of epidemic Vibrio cholerae O1 in rural western Kenya associated with drinking water from Lake Victoria: an environmental reservoir for cholera?

Episodes of cholera stemming from indigenous Vibrio cholerae strains in Australia are mainly associated with environmental sources. In the present study, 10 V. cholerae O1 strains of Australian origin were characterized. All of the strains were serogroup O1 and their conventional phenotypic traits categorized them as belonging to the El Tor biotype. Genetic screening of 12 genomic regions that are associated with virulence in V. cholerae showed variable results. Analysis of the ctxAB gene showed that the Australian environmental reservoir contains both toxigenic and non-toxigenic V. cholerae strains. DNA sequencing revealed that all of the toxigenic V. cholerae strains examined were of ctxB genotype 2. Whole genome PFGE analysis revealed that the environmental toxigenic V. cholerae O1 strains were more diverse than the non-toxigenic environmental O1 strains, and the absence of genes that make up the Vibrio seventh pandemic island-I and -II in all of the strains indicates their pre-seventh pandemic ancestry.

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Detection of viable and viable nonculturable Vibrio cholerae O1 through cultures and immunofluorescence in the Tucumán rivers, Argentina

Revista da Sociedade Brasileira de Medicina Tropical ◽

10.1590/s0037-86822007000400002 ◽

2007 ◽

Vol 40 (4) ◽

pp. 385-390 ◽

Cited By ~ 12

Author(s):

Olga Aulet ◽

Clara Silva ◽

Sol González Fraga ◽

Mariana Pichel ◽

Rosa Cangemi ◽

...

Keyword(s):

Vibrio Cholerae ◽

Physicochemical Parameters ◽

Pearson Correlation ◽

Direct Immunofluorescence ◽

Culture Methods ◽

Conventional Culture ◽

Physical Chemical ◽

Chemical Measurements ◽

Environmental Reservoir ◽

Vibrio Cholerae O1

Vibrio cholerae has been sporadically isolated from rivers in Tucumán, Argentina, since the outbreak in 1991. The aim of this study was to determine the environmental reservoir of the bacterium in these rivers, assessing the presence of Vibrio cholerae non-O1 and O1 (the latter both in its viable culturable and non culturable state) and its relationship to environmental physicochemical variables. 18 water samplings were collected in the Salí River (in Canal Norte and Banda) and the Lules River between 2003 and 2005. Physical-chemical measurements (pH, water temperature, electrical conductivity and dissolved oxygen) were examined. Vibrio cholerae was investigated with conventional culture methods and with Direct Immunofluorescence (DFA-VNC) in order to detect viable non culturable organisms. All isolated microorganisms corresponded to Vibrio cholerae non-O1 and non-O139 (Lules 26%, Canal Norte 33% and Banda 41%). The majority was found during spring and summer and correlated with temperature and pH. Non culturable Vibrio cholerae O1 was detected year round in 38 of the 54 water samples analyzed. Application of the Pearson correlation coefficient revealed that there was no relationship between positive immunofluorescence results and environmental physicochemical parameters. Genes coding for somatic antigen O1 were confirmed in all DFA-VNC-positive samples, whereas the virulence-associated ctxA and tcpA genes were confirmed in 24 samples.

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In vivo Production of Soluble Inorganic Pyrophosphatases in Two Strains of Vibrio cholerae

Bangladesh Journal of Microbiology ◽

10.3329/bjm.v24i1.1235 ◽

1970 ◽

Vol 24 (1) ◽

pp. 38-41

Author(s):

Taslima Taher Lina ◽

Mohammad Ilias

Keyword(s):

Vibrio Cholerae ◽

Specific Activity ◽

Experimental Conditions ◽

Environmental Strain ◽

Cell Extracts ◽

Atcc Strain ◽

The Family ◽

Effects Of Ph ◽

Vibrio Cholerae O1

The in vivo production of soluble inorganic pyrophosphatases (PPases) was investigated in two strains, namely, Vibrio cholerae EM 004 (environmental strain) and Vibrio cholerae O1 757 (ATCC strain). V. cholerae is known to contain both family I and family II PPase coding sequences. The production of family I and family II PPases were determined by measuring the enzyme activity in cell extracts. The effects of pH, temperature, salinity of the growth medium on the production of soluble PPases were studied. In case of family I PPase, V. cholerae EM 004 gave the highest specific activity at pH 9.0, with 2% NaCl + 0.011% NaF and at 37°C. The strain V. cholerae O1 757 gave the highest specific activity at pH 9.0, with media containing 0% NaCl and at 37°C. On the other hand, under all the conditions family II PPase did not give any significant specific activity, suggesting that the family II PPase was not produced in vivo in either strains of V. cholerae under different experimental conditions. Keywords: Vibrio cholerae, Pyrophosphatases (PPases), Specific activityDOI: http://dx.doi.org/10.3329/bjm.v24i1.1235 Bangladesh J Microbiol, Volume 24, Number 1, June 2007, pp 38-41

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