Retrospective study of a plague outbreak by multiplex-PCR

Aims. To determine the effectiveness of multiplex-PCR in Yersinia pestis identification in samples preserved in Cary & Blair medium and to evaluate if this technique would uncover Y. pestis-positives among culture-negative samples. Methods and Results: Multiplex-PCR was used to detect Y. pestis in Cary & Blair preserved bubo aspirates from experimentally infected guinea pigs and to re-analyze samples from a plague outbreak after prolonged storage in Cary & Blair. Variation in the target genes amplification was observed over time. Conclusions: Multiplex-PCR proved to be more effective than culture for plague diagnosis, both for old and recent samples. This technique would be a valuable tool for the plague control programme. Significance and Impact of tahe Study: The multiplex-PCR technique can be useful for the detection and characterization of Y. pestis even when the bacteria are no longer viable and when culture diagnosis has been hampered by the growth of contaminants.