Bacteriophage specificity in the identification of Yersinia pestis as compared with other enterobacteria

Bacteriophage typing of Yersinia pestis and the specificity of the phage among Enterobacteriaceae were investigated. The bacteriophage used for rapid identification of Y. pestis reacted with representative strains of all recognized species of Shigella as well as with Salmonella cholerae-suis. Reactive Shigella serotypes were Sh. dysenteriae 1 and 9, Sh. flexneri 2a, Sh. boydii 1 and 6, and Sh. sonnei. Patterns consisting of isolated plaques (two cases) or absence of plaques were observed when the routine test dilution (RTD) of the phage was used. Results were independent of the incubation temperature (20, 28 or 37 degrees C). Representative strains of Escherichia, Proteus, Providencia and Klebsiella were resistant to the bacteriophage even at 1000 X the RTD established for Y. pestis.