In vitro lecithinase activity and sensitivity to 22 antimicrobial agents of Clostridium perfringens isolated from necrotic enteritis of broiler chickens.

Viable Clostridium perfringens ranging from 10(5) to 10(8) g-1 was detected in all of 88 intestinal content specimens of necrotic enteritis in broiler chickens. In vitro lecithinase activity and sensitivity to 22 antimicrobial agents were determined for the 88 isolates. The activities of lecithinase in the culture filtrate of isolates were estimated to be 0.5 to 4.0 AE ml-1 as alpha-antitoxin equivalent. With reference to antimicrobial activity penicillins and cephazolin showed excellent activity and no resistance; peptides, of the agents used as growth promoters, showed that all except bacitracin had low minimum inhibitory concentration levels (1.6 micrograms ml-1 or less) against this organism; polyethers of monensin, salinomycin and lasalocid were generally adequate in low concentrations while there was a high level of resistance to three tetracyclines in 90 per cent of the strains and all isolates were insusceptible to streptomycin of the aminoglycoside antibiotics.