Prevalence of Yersinia spp. in red meat and chicken marketed in southern Tehran

Background and Aim Yersinia is an important water- and food-borne bacterium causing gastroenteritis in humans. From December 2002 to July 2003, a total of 250 samples -including 158 meat samples and 92 chicken samples- were taken from butcheries and poultry shops operating under the supervision of Tehran University of Medical Sciences. We used a two-step enrichment procedure: phosphate buffer saline was used as primary enrichment within 3 weeks in refrigerator (cold enrichment). Then we applied KOH treatment as secondary enrichment and performed cultures on CIN agar. In this study, 44.4% of all samples showed Yersinia contamination. The prevalence of Yersinia was 29.1% in meat and 70.7% in poultry. Of the 155 Yersinia isolates, 53 (34.2%) were identified as Y. enterocolitica, 47(30.3%) as Y. intermedia, 42 (27%) as Y. fredriksenii and one (0,6%) as Y. kristensenii. Biotyping of Y. enterocolitica showed that 51 strains (39.7%) corresponded to biotype 1A, 13 strains (24.6%) to biotype 1B, one (1.8%) to biotype 2, three (5,7%) to biotype 3 and one (1.8%) to biotype 4. Fourteen strains (26.4%) could not be classified. The high prevalence rates in meat and poultry implies that these products could be widely contaminated with Yersinia, thus serving as important vehicles for transmission to humans.