Genotypic and phenotypic characteristics of Yersinia enterocolitica isolated from the surface of chicken eggshells obtained in Argentina

The prevalence of Yersinia enterocolitica on chicken eggshell surfaces in San Luis, Argentina, was investigated. The pathogenic potential of recovered isolates was assessed by means of phenotypic virulence tests and the presence of the 72-kb pYV plasmid. Antimicrobial susceptibility was determined by the agar diffusion method. DNA digested with XbaI was analyzed by pulsed-field gel electrophoresis (PFGE), and relationships between genomic DNA profiles were established. Eight Y. enterocolitica 132 0:9 strains were recovered after enrichment, for a prevalence of 2.27%. All strains harbored the virulence pYV plasmid, bound Congo red, grew in a low-calcium medium, and autoagglutinated at 37 C. They lacked pyrazinamidase activity and did not hydrolyze esculin. These Y. enterocolitica strains were susceptible to amikacin, ciprofloxacin, chloramphenicol, and trimethoprim-sulfamethoxazole and were resistant to rifampin. According to the genomic DNA patterns obtained by PFGE, the isolates clustered into two groups, I and II. The highest similarity coefficient observed between Y. enterocolitica strains was 0.947. Microbiological controls on production stages of eggs and good culinary practices are necessary to reduce the risk of Y. enterocolitica infection for consumers.