Investigations on prevalence and antimicrobial resistance of enterohaemorrhagic Escherichia coli (EHEC) among dairy farms in the north part of the Republic of Bulgaria

Abstract

Original Scientific Article Mac Vet Rev 2015; 38 (1): 21-29 Available online at www.macvetrev.mk Over a 2-year period, from January 2011 to May 2013, a total of 1094 faecal swab samples were collected from cattle at different age at 4 farms in North Bulgaria: Okorsh, Slavyanovo (Popovo municipality), Dobri dol and Trem. Out of them, 36 coli strains (3.3%) positive in the E. coli O:157 antiserum agglutination test and identified by the BBL CRYSTAL identification system as belonging to the E. coli O:157 serotype were isolated. The distribution of isolates was as followed: 5 (0.5%) E. coli O:157 strains at the Okorsh dairy cattle farm, 7 (0.6%) E. coli isolates at the Slavyanovo dairy farm, 16 (1.5%) isolates at the Dobri dol farm and 8 (0.7%) isolates at the Trem farm. Colibacteria exhibited 100% sensitivity to oxyimino-cephalosporins, gentamicin and enrofloxacin, and were resistant to ampicillin (19.4%) and tetracycline (41.6%). From the 15 strains resistant to tetracycline, 11 were isolated from the cows at Dobri dol, while the other 4 originated from the other three farms. The 7 ampicillin-resistant E. coli isolates were detected only at the Dobri dol cattle farm.