Abstract. In vitro toxin production is an important tool not only for diagnostic purposes but also for the study of pathogenesis of Clostridium perfringens infections. The present study was carried out to compare the level of toxin production by several strains of C. perfringens type A, isolated from the intestine of animals, when cultured in 3 different conventional culture media. Six strains of C. perfringens type A isolated from the small intestine of healthy sheep were cultured in commercial cooked meat medium (CMM), brain heart infusion (BHI), and tryptone glucose yeast (TGY). Intravenous lethality in mice and phospholipase C (PLC) activity were measured in filtered culture supernatants. Lethality of culture supernatants was highest for all isolates when grown in BHI, followed by CMM. No supernatants from any isolates grown in TGY produced lethality in mice. Phospholipase C activity was highest when the isolates were grown in BHI and CMM and significantly lower when grown in TGY.

The presence and molecular characterization of Clostridium perfringens in healthy Merino lambs over a six-month period was investigated in this study. Overall, a high prevalence of C. perfringens was detected, even in day-old lambs. Even though the majority of the isolates were characterized as being of type A, types C and D were also isolated. Furthermore, a high genetic diversity was observed by PFGE among the type A isolates.