A Turkey survey of hygiene indicator bacteria and Yersinia enterocolitica in raw milk and cheese samples

Abstract

In this research, a total of 200 dairy (raw milk, cheese) samples obtained from Ankara, were examined for the presence of Yersinia spp., total coliform and Escherichia coli. As expected, raw milk 55% (55/100) were significantly contaminated with Yersinia spp., than cheese samples 14% (14/100). Y. enterocolitica was the most commonly isolated species, and was recovered from 47.3% in raw milk 35.7% in cheese samples. The other Yersinia spp. were identified as Y. frederiksenii (31.0%, 21.4%), Y. kristensenii (12.7%), Y. intermedia (7.2%, 7.1%) and atypical Yersinia spp. (1.8%, 35.7%) in raw milk and cheese samples, respectively. All the samples of cheese examined were negative for Y. kristensenii. All Y. enterocolitica strains tested gave negative results in the autoagglutination tests and crystal violet binding test. Furthermore total coliform bacteria and E. coli were investigated in these samples. According to the analysis results, most of the samples containing Yersinia spp.were found high number of viable count cell total coliform than E. coli. Total coliform bacteria and E. coli, were detected (3.0 × 10 4 cfu/ml and 1.5 × 10 4 cfu/ml) in four milk samples containing Y. enterocolitica while, they were detected (2.5 × 10 4 cfu/ml and 1.0 × 10 4 cfu/ml) in eight milk samples containing Y. enterocolitica. In the present study, total coliform bacteria and E. coli were detected >1.1 × 10 5 cfu/g in six cheese samples containing Y. enterocolitica and atypical Yersinia spp. The results indicate that Yersinia spp. is more likely to be isolated from foods with a high level of coliforms than from foods with low coliform counts.