Prevalence of E. coli O157:H7 in Dairy Cattle and the Farm Environment

Abstract

The aims of this study were, to detect the presence, and investigate the seasonal prevalence of E. coli O157:H7 from feces and milk of the healthy dairy cattle in various age groups, and from feces of the other animals (dog, cat etc.) present in the farms. Also environmental samples from the farms which belonged to public or private establishments, in the Marmara Region of Turkey were included. For that purpose, 96 fecal and milk samples from the same animals (except death and slaughtering) and 96 environmental samples were collected from the determined 10 farms, in fall and spring periods. In total, of 576 (288 samples in the fall period while 288 samples in the spring) samples were examined. The samples were collected totally from 139 animals because of the new animals were added due to death or slaughtering in the spring period. All samples were enriched in modified Tryptic Soya Broth. After the immunomagnetic separation, O157 Dynabeads and bacterial suspensions were inoculated onto sorbitol MacConkey agar with cefixime and tellurite. Sorbitol negative colonies were inoculated onto sorbitol MacConkey agar supplemented with 4-methylumbelliferyl-β-D-glucuronide. Suspected colonies which were chosen from this medium were applied for latex and tube agglutination assays for characterization of O157 serogroup, biochemical tests and tube agglutination assay for detecting H7 antigen respectively. In the fall period, E. coli O157 was isolated from one environmental sample and E.coli O157:H7 from one fecal sample. In the spring period, E. coli O157 was isolated from 10 and E. coli O157:H7 from one fecal sample. Seven of E. coli O157 isolates were from the same farm which tested negative during in the first sampling. In total, 576 samples were examined and two samples were identified as E. coli O157:H7 (0.35 %) and confirmed by PCR assay applied on the BAX System Q7. E. coli O157:H7 which was identified in the fall period was not isolated in the spring period. Because, the animal which fecal sample taken from was newly added because of slaughtering or death. Seasonal effect was detected significant only in the isolation rate of E. coli O157 in feces (p<0.01).