Antimicrobial Drug Resistance in Escherichia coli Including an O157:H7 Isolate from Feces of Healthy Goats in Grenada

Aim: To determine: the occurrence of Escherichia coli including the O157:H7 serotype in feces of healthy goats in 10 randomly selected farms in Grenada and the antimicrobial drug resistance in E. coli isolated from feces of the tested goats.
Study Design: During the period of May to July, 2014, fecal samples were obtained from randomly selected healthy goats in 10 farms in Grenada and analyzed in the bacteriology laboratory, in the Pathobiology Department, School of Veterinary Medicine, St. George’s University, Grenada.
Methodology: Fecal samples were obtained from 70 randomly selected healthy goats in 10 farms in Grenada and cultured for E. coli and tested for O157:H7 serotype by the presence of non-sorbitol fermenting colonies and a positive reaction to O157-agglutination latex kits.
Results: All the 70 tested goats were culture positive for Escherichia coli. A total of 140 E. coli isolates were recovered and analyzed for the presence of non-sorbitol fermenting colonies and O157-agglutination. Of the 140 yielded E. coli, 11 (8%) isolates were non-sorbitol fermenters but only one (<1%) out of the non-sorbitol fermenters gave a positive reaction to the two E. coli O157:H7 latex kits. Antimicrobial susceptibility tests against 12 drugs showed susceptibility of the single E. coli O157:H7 isolate recovered to all the tested antibiotics. Among the non-O157:H7 isolates, the susceptibility rates to amoxicillin-clavulanic acid, ciprofloxacin, enrofloxacin, gentamicin, cefepime and ceftazidime ranged from 99% to 100%. The resistance rate to ampicillin, gentamicin, nalidixic acid, streptomycin, trimethoprim-sulfamethoxazole, and tetracycline observed was very low except to streptomycin (19%). Resistance to two or more antibiotics was observed only in 5% of the 140 E. coli isolates.
Conclusion: Our study revealed that presently, healthy goats in Grenada are not major reservoirs for the E. coli O157:H7 serotype and for multiple resistant E. coli strains.