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Applied and Environmental Microbiology, November 2009, p. 6981-6985, Vol. 75, No. 22
0099-2240/09/$08.00+0 doi:10.1128/AEM.00517-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Department of Microbiology, Xiamen Centre for Disease Control and Prevention, Xiamen, Fujian Province, China,1 Molecular Diagnostics Laboratory, Department of Biomedical Sciences, School of Life Sciences, Xiamen University, Xiamen, Fujian Province, China2
Received 2 March 2009/ Accepted 11 September 2009
Vibrio cholerae is a natural inhabitant of the aquatic environment. However, its toxigenic strains can cause potentially life-threatening diarrhea. A quadruplex real-time PCR assay targeting four genes, the cholera toxin gene (ctxA), the hemolysin gene (hlyA), O1-specific rfb, and O139-specific rfb, was developed for detection and differentiation of O1, O139, and non-O1, non-O139 strains and for prediction of their toxigenic potential. The specificity of the assay was 100% when tested against 70 strains of V. cholerae and 31 strains of non-V. cholerae organisms. The analytical sensitivity for detection of toxigenic V. cholerae O1 and O139 was 2 CFU per reaction with cells from pure culture. When the assay was tested with inoculated water from bullfrog feeding ponds, 10 CFU/ml could reliably be detected after culture for 3 h. The assay was more sensitive than the immunochromatographic assay and culture method when tested against 89 bullfrog samples and 68 water samples from bullfrog feeding ponds. The applicability of this assay was confirmed in a case study involving 15 bullfrog samples, from which two mixtures of nontoxigenic O1 and toxigenic non-O1/non-O139 strains were detected and differentiated. These data indicate that the quadruplex real-time PCR assay can both rapidly and accurately detect/identify V. cholerae and reliably predict the toxigenic potential of strains detected.
Published ahead of print on 18 September 2009.
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