[Mode of sample preparation for pseudotuberculosis laboratory diagnosis by polymer chain reaction method]

A mode of feces sample preparation was developed for polymerase chain reaction (PCR) assay. It was based on alkaline treatment of the material. This treatment killed the most part of indigenous microflora, whereas Yersinia survived, because it was relatively resistant to alkaline. The mode was tested using human feces artificially contaminated with Yersinia pseudotuberculosis. Positive responses in samples containing 10(3)-10(8) microbial cells per ml were obtained by PCR assay with Yersi and Yers2, Invl and Inv2, YP3 and YP4 primers. Diagnostic efficiency of PCR for patients, small mammals, and washings from environmental objects was 4.75, 1.66, and 2.12 times higher than diagnostic efficiency of bacteriological analysis of these samples, respectively. Positive results in PCR were obtained at the day of the material collection and treatment, whereas Y. pseudotuberculosis was isolated only after 8-20 days. Positive samples in PCR and in bacteriological analysis were found to coincide. A brief scheme of the Y. pseudotuberculosis laboratory diagnosis is suggested. According to this scheme, target-oriented bacteriological assay is performed only in those samples, in which preliminary PCR assay after 1-3 days of incubation gave positive results of Y. pseudotuberculosis DNA detection.