Microbiological and Molecular Methods to Identify and Characterize Toxigenic Vibrio cholerae From Food Samples

Vibrios are Gram-negative γ-proteobacteria that are ubiquitous in marine, estuarine, and fresh-water environments and encompass a diverse group of bacteria, including many facultative symbiotic and pathogenic strains. Toxigenic Vibrio cholerae strains belonging to the serogroups O1 and O139 are the etiologic agents of cholera. Apart from water-borne transmission, food plays an important role in the transmission of cholera. In the chapter, we present the basic methods used for isolation, identification, and PCR-based biotype differentiation, serotype confirmation, and detection of molecular markers of virulence. We also describe standardized methods to fingerprint the strains of V. cholerae by ribotyping and pulsed-field gel electrophoresis. These molecular typing techniques are now acknowledged as excellent tools in tracing the source of infection and tracking the spread of the disease.