Numerical classification of Yersinia enterocolitica and relationship between its subdivision and pathogenicity

A total of 102 strains of Yersinia enterocolitica were studied on their morphology, physiology and biochemistry at 25 degrees C. All data coded in binary notation and similarities between each pair of strains by simple matching coefficient were calculated using subsequent computation. Four clusters were distinguished within the 102 strains at a similarity level of 90--93%. Although some discrepancies were recognized on reactions of indole, xylose, esculin and salicin, it was evident that 3 of the 4 groups in the present study correspond to the DNA relatedness groups of Brenner et al., respectively. On the other hand, it was confirmed, using feeding tests with monkeys, that only the group 1 was enteropathogenic. These results support the suggestion of Brenner et al. that their DNA relatedness group 1 is true Y. enterocolitica.