MOLECULAR TYPING OF YERSINIA-PSEUDOTUBERCULOSIS BY USING AN IS200-LIKE ELEMENT

The IS200 like insertion sequence (IS) is a 708-bp element recently fo und in Yersinia pestis. Its nucleotide Sequence is 85% identical to th at of IS200 recovered in most Salmonella enterica isolates. It is also present in multiple copies in Y. pseudotuberculosis. In contrast, thi s IS is found in some (biotype 1B strains) but not other Y. enterocoli tica strains and is absent in the nonpathogenic yersiniae: Y. frederik senii, Y. kristensenii, Y. intermedia, Y. bercovieri, and Y. mollareti i. The number and locations of the ISs in the Y. pseudotuberculosis ge nome vary among strains, resulting in a high degree of polymorphism, b ut IS fingerprints are stable after multiple subcultures of clinical i solates. The discriminative power of IS typing is better than that of ribotyping and almost as good as that of the time-consuming method of pulsotyping. Overall, IS200-like is a useful molecular marker in deter mining the epidemiology of Y. pseudotuberculosis infections.