The Prevalence of Yersinia Enterocolitica in Farm Bulk Milk

A total of 350 samples of individual cow’s milk, bulk milk andenvironmental samples (faecal swabs), collected from different dairyfarms in Dakahlia province, were examined bacteriologically fordetection and identification of existing Yersinia.The results reported in this investigation declared that Yersiniaspp. could be detected in 8%, 6% and 2% of individual cow’s milk, bulkmilk and cow’s faecal samples, respectively.Yersinia enterocolitica was isolated from 3.3% of individual cow’smilk, 2% of bulk milk and 1% of faecal samples. While Yersiniakristensenii and Yersinia -intermedia were found in 0.7% & 3% and 4%& 1% of examined individual and bulk samples, respectively. OnlyYersinia intermedia could be detected in 1% of cow’s faecal swabs.Thermal inactivation of Yersinia enterocolitica in milk revealedthat Yersinia enterocolitica was destroyed at 62°C after one min. ofexposure. At 60°C the thermal resistance start to develop whichincrease with shorten the time of exposure, as growth of Ye rsi niaenterocolitica was very good/one min. and deminished to be nondetectable/5 min. The thermal death time was 45 min. at 55°C.Yersinia enterocolitica could survive in artificially contaminatedyoghurt stored at refrigeration temperature (7 ± 1°C) for 9 days andcould persist in soft cheese salted with 5% sodium chloride up to 21 day