Epidemiological, clinical and microbiological features of Yersinia enterocolitica infections in a community during a four-year period.

Epidemiological and clinical features of 17 cases (13 children) of yersiniosis treated in a hospital over a four-year period, as well as factors associated with virulence, antibiotic resistance and plasmids in Yersinia enterocolitica strains from these patients were studied. The proportion of Y. enterocolitica was 3.57% of all fecal cultures positive for enteric pathogens, with 13 sporadic episodes and one outbreak. In 11 cases the infection was unimicrobial. The clinical presentation was: gastroenteritis (14 cases), pseudoappendicitis (1 case) and asymptomatic (2 cases). Eight cases needed hospital care, and 8 required antimicrobial treatment. None of the isolated bacterial strains produced pyrazinamidase, hemolysins, elastase, fibrinolysine, colicines or aerobactin. Eight strains showed calcium dependence, 7 of them exhibited autoagglutination, serum resistance, crystal violet binding and carried a 42 MDa plasmid related with virulence. Two strains carried a 3.3 MDa R-plasmid that encoded streptomycin-sulfadiazine resistance. The restriction analysis showed that the virulence plasmids constitute one variety and R-plasmids another.