Prevalence of Yersinia enterocolitica in Hake (Merluccius hubbsi) Fillets

Yersinia enterocolitica is a human pathogenic bacterium. The prevalence of Y. enterocolitica in refrigerated hake fillets sold for human consumption in retail stores was investigated in order to determine the degree of pathogenicity. Three hundred samples were enriched in 0.067 M phosphate-buffered saline, pH 7.6, with 1% sorbitol and 0.15% biliary salts, postenriched in 0.5% KOH, and isolated in salmonella-shigella agar and MacConkey agar. Twelve strains of Yersinia were isolated from the whole group of samples, 11 (91.6%) of which corresponded to Y. enterocolitica and 1 (8.3%) to Y. intermedia . The Yersinia strains recovered were Y. enterocolitica B1 O:5 Lis X_z (1 strain), Y. enterocolitica B3 O:5 (1 strain), Y. enterocolitica B1 O:6,30-6,31 (1 strain), Y. enterocolitica B1 O:7,8-8-8,19 (1 strain), Y. enterocolitica B1 O:7,8-8-8,19 Lis Xz (7 strains) and Y. intermedia B1 O:40 Lis Xo (1 strain). Of the 12 strains isolated, 8 (66.6%) were recovered by alkaline postenrichment. The first two strains were positive for virulence tests (autoagglutination and calcium dependence for growth at 37°C). The antibiotic susceptibility of the isolated strains was studied by the agar-diffusion method according to Bauer-Kirby, modified by Barry. Some of the isolated strains were potentially pathogenic, representing a risk for human health.