The occurrence of antibiotic resistance in Clostridium perfringens from pigs.

Porcine faecal specimens were collected from piggeries in south western Australia. Clostridium perfringens strains were isolated, identified, and examined by disc susceptibility tests for their resistance to several antibiotics. The resultant data were correlated with the known exposure of the animals to antimicrobial agents in the feed or water. The results showed that the percentage of C. perfringens isolates resistant to tetracycline or the macrolide-lincosamide antibiotics was significantly higher from weaners fed one of a number of combinations of antimicrobial agents than was the percentage of resistant strains isolated from the one piggery that did not use antimicrobials. No differences in the levels of chloramphenicol or penicillin resistance were observed. Genetic analyses showed that 3 of the resistant strains carried conjugative R-plasmids which carried the tetracycline resistance determinants.