Antimicrobial Susceptibility Profiles of Escherichia coli Recovered from Feces of Young Healthy Domestic Pigs in Grenada, West Indies

Aim: To determine the antimicrobial susceptibility profiles of E. coli isolates of porcine origin in Grenada, West Indies.

Study Design: During the period of May to July, 2014, rectal swab samples were collected from pigs of six weeks to 12 week of age, from randomly selected small scale pig farms from the six parishes of Grenada and analyzed in the bacteriology lab in the Pathobiology Department, School of Veterinary Medicine, St. George’s University, Grenada.

Methodology: A total of 180 rectal swab samples were examined for the presence of E. coli by culture. All the isolates were tested against 12 antibiotics using the standard Kirby-Bauer disc diffusion method.

Results: All the 180 tested pigs were culture positive for E. coli. Antimicrobial susceptibility tests against 12 drugs showed susceptibility of all the E. coli isolates to amoxicillin-clavulanic acid, cefotaxime, ceftazidime, ciprofloxacin, imipenem, and gentamicin. Rate of resistance to tetracycline (96%) was the highest. Low rates of resistance to trimethoprim-sulfamethoxazole (3%), ampicillin (3%), chloramphenicol (1%), neomycin (1%) and cephalothin (1%) were observed. However, 22% of isolates showed intermediate resistance to cephalothin. Only 6% of the E. coli isolates showed resistance to two or more antibiotics.

Conclusion: This study showed that young healthy pigs in Grenada are not major reservoirs for multiple resistant E. coli. This study also confirms the inefficacy of tetracycline against E. coli of porcine origin.