Antibiotic resistance of Escherichia coli O157:H7 isolated from cattle and sheep

A total of 102 Escherichia coli O157:H7 colonies recovered from 11 cattle and 14 sheep were collected and tested for their antibiotic resistance profiles using a disc diffusion method, according to the Clinical and Laboratory Standards Institute. Four (36.36 %) of the 11 cattle E. coli O157:H7 isolates were resistant to cephalothin, one (9.09 %) isolate was resistant to streptomycin, and one (9.09 %) to nalidixic acid. Two (14.28 %) of the 14 sheep E. coli O157:H7 isolates were resistant to sulphamethoxazole, one (7.14 %) isolate was resistant to sulphonamide compounds, and one (7.14 %) to streptomycin. All cattle and sheep isolates were found to be susceptible to cephazolin, gentamicin, ciprofloxacin, imipenem, trimethoprim/ sulphamethoxazole, chloramphenicol, trimethoprim, and ceftiofur. Six cattle isolates were susceptible at a ratio of 54.54 %, and 11 (78.57 %) isolates from sheep were susceptible to all 20 antibiotics tested. As an overall result, 68 % of the E. coli O157:H7 isolates belonging to cattle and sheep were susceptible to all antibiotics tested. On the other hand, most of the E. coli O157:H7 isolates were intermediately resistant to streptomycin, cephalothin, sulphamethoxazole, ampicillin, and kanamycin.