COMPARATIVE-ANALYSIS OF YADA AND AIL POLYMERASE CHAIN-REACTION METHODS FOR VIRULENT YERSINIA-ENTEROCOLITICA

The performance of two polymerase chain reaction (PCR) methods targeti ng chromosomal ail and plasmid-borne yadA gene sequences in the analys is of a variety of virulent and avirulent Yersinia enterocolitica stra ins was examined. All of the 45 virulent isolates tested were positive in the ail PCR method, whereas the yadA PCR method gave positive resu lts with only 39 of these isolates, possibly due to virulence plasmid loss during subculturing of the six PCR-negative isolates. None of a p anel of avirulent Y. enterocolitica strains, other Yersinia spp. and n on-Yersinia bacteria tested gave positive results with either of the P CR methods, thus demonstrating their specificity. Both PCR methods pro vided excellent detectability in the assay of broth suspensions of cel ls, giving positive results with fewer than 5 c.f.u. per reaction usin g different serotypes. We conclude that the ail PCR method will provid e a reliable tool for the analysis of virulent Y. enterocolitica.