Intra- and interspecies relatedness of Yersinia pestis by DNA hybridization and its relationship to Yersinia pseudotuberculosis

The biochemical characteristics of Yersinia pestis are presented and compared with those of Y. pseudotuberculosis. Motility at 28°C, urease, fermentation of rhamnose, and growth rate on nutrient agar are the best means of separating these organisms. DNA hybridization studies demonstrated that Y. pestis strains are 90% or more interrelated and that Y. pestis and Y. pseudotuberculosis are indistinguishable by DNA relatedness. On the basis of DNA data and biochemical and antigenic similarity, these organisms should be treated as two separate subspecies of the same species. Y. pseudotuberculosis was described before Y. pestis and therefore has priority. Y. pseudotuberculosis subsp. pseudotuberculosis and Y. pseudotuberculosis subsp. pestis are recommended as new designations for Y. pseudotuberculosis and Y. pestis. For medical purposes, Y. pestis and Y. pseudotuberculosis can and should continue to be used.