Yersinia enterocolitica : Biochemical, Serological, and Gas-Liquid Chromatographic Characterization of Rhamnose-, Raffinose-, Melibiose-, and Citrate-Utilizing Strains

Thirteen atypical Yersinia enterocolitica isolates, all fermenting rhamnose, raffinose, and melibiose and utilizing sodium citrate within 24 to 48 h at 22°C ( Y.e.rh +), were examined biochemically-serologically, and by gas-liquid chromatography. These data, as well as cultural, biochemical, and antibiotic susceptibility data gathered from two previous studies involving (i) these same atypical Y.e.rh + isolates, (ii) Y. enterocolitica serotypes O:1 through O:15 (rhamnose, raffinose, and citrate negative [ Y.e.rh −]), (iii) Y. enterocolitica serotype O:16 (rhamnose positive but raffinose and citrate negative), and (iv) Yersinia pseudotuberculosis serogroups I through V were statistically compared. Both preand postabsorption agglutination studies demonstrated the serological distinctiveness of Y.e.rh + from Y.e.rh − and Y. pseudotuberculosis . At the same time, three immunological groups among the 13 Y.e.rh + strains were seen; 8 corresponded to Y. enterocolitica serotype O:17; 1 to Y. enterocolitica serotype O:16; and the remaining four were nontypable in antisera against known Y. enterocolitica antigen types. Each of the three Yersinia groups tested chromatographically produced acetic and lactic acids. Both Y.e.rh − and Y.e.rh + formed propionic acid, but only Y.e.rh + produced detectable amounts of succinic acid. Based on 49 variables, statistical analysis of the three Yersinia groups studied placed each of the Y.e.rh + strains in a homogeneous group separate from both Y.e.rh − and Y. pseudotuberculosis . These data, coupled with deoxyribonucleic acid homology studies of Brenner and co-workers (D. J. Brenner, A. G. Steigerwalt, D. F. Falcao, R. E. Weaver, and G. R. Fanning, Int. J. Syst. Bacteriol. 26 :180-194, 1976), support the distinctiveness of Y.e.rh + from typical Y. enterocolitica and Y. pseudotuberculosis .