IN-VITRO SUSCEPTIBILITY OF CLOSTRIDIUM-PERFRINGENS ISOLATED FROM FARM-ANIMALS TO GROWTH-ENHANCING ANTIBIOTICS

Minimal inhibitory concentration (MIC) determinations were carried out with seven growth-enhancing antibiotics against 95 Clostridium perfri ngens field isolates obtained during 1991 and 1992 from poultry, pigs and calves. All were resistant to 64 mug ml-1 of the bambermycin antib iotic, flavomycin (flavophospholipol) and susceptible to avoparcin (MI C90 0.25 mug ml-1), avilamycin (MIC90 0.5 mug ml-1) and salinomycin (M IC90 less-than-or-equal-to 0.12 mug ml-1). Acquired resistance against bacitracin was detected in some isolates from poultry and bovines and resistance to tylosin and virginiamycin in some strains from all spec ies investigated. Overall, the prevalence of resistance was comparable to the low levels recorded in 1979 in Cl. perfringens isolates from t he same animal host species.