H.H. Mollaret

Yersinia frederiksenii: A new species of enterobacteriaceae composed of rhamnose-positive strains (formerly called atypicalyersinia enterocolitica orYersinia enterocolitica-Like)

Yersinia frederiksenii sp. nov. is defined biochemically and genetically.Y. frederiksenii stains belong to three separate DNA relatedness groups, each of which is separable fromY. enterocolitica, Y. intermedia, Y. kristensenii, Y. pseudotuberculosis, andYersinia biotypes X1 and X2. The threeY. frederiksenii DNA relatedness groups, 6175, 2581-77, and 867, were represected by 10, 3, and 1 strain, respectively. All three groups were phenotypically similar. Pending additional study, it was decided to retain them all inY. frederiksenii. The positive rhamnose reaction separatesY. frederiksenii fromY. enterocolitica, Y. kristensenii, andYersinia biotype X1. A positive sucrose reaction distinguishesY. frederiksenii from the rhamnose-positive, sucrose-negativeYersinia biotype X2. Negative reactions for melibiose, raffinose, and α-methyl-d-glucoside distinguishY. frederiksenii fromY. intermedia. A negative melibiose reaction and positive reactions for ornithine decarboxylase, indole, sucrose, sorbose, sorbitol, inositol, and Voges-Proskauer separateY. frederiksenii fromY. pseudotuberculosis. Strain 6175 (=CIP 80-29) is proposed as the type strain forY. frederiksenii.

Intra- and interspecies relatedness ofYersinia pestis by DNA hybridization and its relationship toYersinia pseudotuberculosis

The biochemical characteristics ofYersinia pestis are presented and compared with those ofY. 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 thatY. pestis strains are 90% or more interrelated and thatY. pestis andY. 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 beforeY. pestis and therefore has priority.Y. pseudotuberculosis subsp.pseudotuberculosis andY. pseudotuberculosis subsp.pestis are recommended as new designations forY. pseudotuberculosis andY. pestis. For medical purposes,Y. pestis andY. pseudotuberculosis can and should continue to be used.

Biochemical, serological, and phage typing characteristics of 459Yersinia strains isolated from a terrestrial ecosystem

The origins of human contamination withYersinia enterocolitica are still unknown. We have investigated the major components of a terrestrial ecosystem (soil, earthworms, field voles, shrews, crops, hares, rabbits, and birds) for the presence ofYersinia. Four hundred fifty-nine strains ofYersinia were isolated. We report the first isolations of typicalY. enterocolitica belonging to classical or new biotypes and ofY. enterocolitica-like organisms (sucrose negative; rhamnose positive; melibiose and rhamnose positive) from soil samples, earthworms, crops, and birds. Sucrose-negativeY. enterocolitica strains and biotypes 1, 2, and 3, usually associated with human nonmesenteric syndromes, are predominant in soil, which can be considered as a reservoir for these biotypes.Y. enterocolitica serogroups O∶3 and O∶9, strains of which are responsible in Europe for human mesenteric syndromes, were not found in this study. The epidemiology ofY. enterocolitica infections is discussed.

Mechanisms of acquired resistance to plague in mice infected byYersinia enterocolitica O3

Yersinia enterocolitica, serogroup O3, injected either intravenously or intragastrically to mice, induced acquired resistance toYersinia pestis. The digestive infection byY. enterocolitica O3 was mostly located into the Peyer’s patches and the ileum wall; the blood, the mesenteric lymph node, and the spleen were not invaded. Serum fromY. enterocolitica O3 convalescing mice failed to protect passively againstY. pestis. In contrast, lymphoid cells from the stimulated Peyer’s patches permitted transfer of efficient bactericidal activity againstY. pestis.

Yersinia enterocolitica among small wild mammals in France.

A survey of Yersinia enterocolitica was made in two French areas (Indre and Alsace) in several components of the terrestrial ecosystem. Y. enterocolitica has been isolated from several habitats and from numerous species of small mammals. The trap line method enabled us to estimate the density of the two abundant small mammal species, Microtus arvalis and Apodemus sylvaticus, and the densities of Y. enterocolitica carriers. The frequency of isolation was high when temperatures were low, but did not seem to be in direct relationship with animal densities. Infectious lesions were never found in spleens or intestines of 1893 captured animals. Samples of fresh water, fresh-water fish, soil and earthworms were occasionally collected. A total of 163 strains were isolated. Of these, 99 were of biochemical type 1; 20 different 0 serogroups were found.

Conservation expérimentale de Brucella suis durant quatre ans dans la terre: Intérêt épidémiologique

Resume Une souche de Brucella suis a ete conservee vivante durant quatre ans et deux mois, au laboratoire, en terre de jardin autoclavee.