Antibiotic resistance profiles of Escherichia coli O26, O145, and O157:H7 isolated from swine in the Eastern Cape Province, South Africa

© 2017 by the Asian Pacific Journal of Tropical Disease. Objective: To conduct antimicrobial resistance profile of Escherichia coli (E. coli) serogroups isolated from swine that are regularly exposed to clinically important antibiotics in the farms, calculate multiple antibiotic resistance index and determine the presence of resistance determinants. Methods: Identification of the E. coli isolates (n = 169), delineation into serogroups, and resistance genes determination were done using PCR technique. Antibiotic susceptibility testing against 16 antibiotics was done using the disk diffusion method. Results: The susceptibility test showed that most of the isolates were highly resistant to tetracycline (long-acting counterpart), oxytetracycline and also to ampicillin (84%-100%). On the other hand, a relatively high susceptibility to norfloxacin (83%-100%), ciprofloxacin (63%-100%), gentamicin (77%-100%), and chloramphenicol (77%-100%) was observed among the isolates. The multiple antibiotic resistance indices ranged from 0.2 to 0.7 while genes encoding resistances to tetracycline, streptomycin and ampicillin were detected in 48%, 22%, and 78% of all the E. coli isolates, respectively. Conclusions: Findings from this study revealed that swine from this area can be reservoirs of multiple antibiotic resistances. There is need for regular surveillance of antimicrobial usage in swine industries and the use of sub-therapeutic doses of these agents should be discouraged.