A combination of different polymerase chain reaction (PCR) assays for the presumptive identification of Yersinia pestis

A combination of four polymerase chain reaction (PCR) assays targeting the Yersinia pestis-specific plasmoidal genes of the fraction 1 capsular antige n and plasminogen activator/coagulase, the gene of the V antigen of the Yer sinia virulence plasmid, and the chromosomal 16S rRNA gene was evaluated fo r the identification of Y. pestis isolates. All four assays were subjected to the same preparation technique, reagents and cycling conditions. Eightee n Y. pestis, 66 Y. pseudotuberculosis, 40 Y. enterocolitica strains, the ty pe strains of the other Yersinia species, and 20 other pathogenic bacterial strains were investigated. By using the proposed combination of PCR assays all Y. pestis strains were identified correctly. The applicability of this combination of PCR assays was demonstrated by the detection of Y. pestis D NA in spiked tissues from Rattus normegicus and fleas (Xenopsylla cheopis a nd Ctenocephalides spp.). As little as 60 genome equivalents were detected. This system is applicable for monitoring Y. pestis and its vectors in enzo otic natural foci and in the diagnosis of plague in humans and animals.