[Comparison between biotype of Vibrio cholerae O1 and genotype using polymerase chain reaction]

To compare between biotype of Vibrio cholerae O1 and genotype using polymerase chain reaction (PCR), 9 classical and 81 El Tor biovar strains were investigated for hemolysis, agglutination of avian erythrocytes, VP test reactivity, sensitivity to both polymyxin B and classical phage IV, and genotype using PCR amplification of hlyA, tcpA, rtxA and rtxC. One classical biovar strain showed atypical reaction upon agglutination of avian erythrocytes. Eighteen El Tor biovar strains showed atypical reactions, with the exception of sensitivity to polymyxin B. By PCR detection of hlyA, rtxA and rtxC amplifications, all classical biovar strains possessed only classical type hlyA, while all El Tor biovar strains possessed El Tor type hlyA, rtxA and rtxC. By PCR analysis of amplicons, all classical biovar strains possessed classical type tcpA. One ctx-negative El Tor biovar strain possessed degenerated classical type tcpA and 4 ctx-negative El Tor biovar strains had no detectable tcpA. These results indicated that genotype of V. cholerae O1 using PCR detection of hlyA, rtxA and rtxC was consistent with biotype of the organism, suggesting that analysis of the genotype of the organism was as effective as by biochemical properties. However, PCR detection of hlyA is most appropriate for the biotyping of V. cholerae O1, as compared to biochemical properties, since El Tor biovar was originally distinguished from classical biovar strains by the hemolytic reaction.