Molecular typing of epidemic and nonepidemic Vibrio cholerae isolates and differentiation of V. cholerae and V. mimicus isolates by PCR-single-strand conformation polymorphism analysis

Aims: To examine the utility of polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) analysis to differentiate epidemic and nonepidemic Vibrio cholerae isolates as well as to differentiate V. cholerae and Vibrio mimicus isolates. Methods and Results: By both PCR-restriction fragment length polymorphism (RFLP) and PCR-SSCP analysis of groEL-I on chromosome 1 and groEL-II on chromosome 2, V. cholerae isolates gave distinct profiles compared with V. mimicus isolates. In addition, PCR-SSCP analysis of groEL-I and groEL-II could differentiate between V. cholerae epidemic and nonepidemic isolates. Interestingly, the relationships among strains based on groEL-I from chromosome 1 and groEL-II from chromosome 2 were congruent with each other, highlighting the conserved evolutionary history of both chromosomes in this species. Conclusions: PCR-SSCP is a powerful typing technique, which has the ability to differentiate V. cholerae and V. mimicus isolates. The epidemic V. cholerae O1/O139 serogroup isolates represent a clonal complex distinct from non-O1/non-O139 isolates that can be identified by PCR-SSCP analysis. Significance and Impact of the Study: This study highlights the effectiveness of using reliable molecular typing methods and in particular PCR-SSCP, to identify genetic variation among V. cholerae and V. mimicus isolates.