Molecullar Typing, Prevalence of netB and Antimicrobial Susceptibility among Clinical Isolates of Clostridium perfringens from Chickens in Southern China

Clostridium perfringens is an important pathogen of animals and humans and is the causative agent of Necrotic Enteritis (NE) in poultry. This study focused on the typing of intestinal C. perfringens isolates (n = 78, 54 from chickens with NE, 24 from healthy chickens) from China's Southern Guangdong province. All isolates were classified as type A using multiplex PCR assay. The recently described toxin gene associated with NE in chickens, netB was found in 21 (26.9%) of the isolates (18 from chickens with NE and 3 from unrelated chickens with no evidence of NE). The in vitro susceptibility results showed that ceftriaxone showed highest activity with lowest MIC50 values (0.25-0.5 mu g mL(-1)) followed by cefotaxime (0.25-4 mu g penicilin (0.5-2 mu g mL(-1)). However, most of the isolates were resistant to lincomycin, tetracycline, metronidazole and neomycin as evident by the high MIC50. Furthermore, 70.5% of the isolates (n = 55) were simultaneously resistant to > 4 antibiotics and 30.8% of the isolates (n = 24) were resistant to all the antimicrobials tested. To the knowledge this is the first study of the prevalence of C. perfringens in broiler chickens in China and the first to examine the isolates for the recently identified novel toxin genes, netB.