Prevalence of <i>netB-</i>positive <i>Clostridium perfringens</i> in Italian poultry flocks by environmental sampling

Abstract

<i>Clostridium perfringens</i> type G is one of the pathogens involved in enteric diseases in poultry. NetB, a pore-forming toxin, is considered the main virulence factor responsible for necrotic enteritis during <i>C. perfringens</i> infection. We carried out a field study involving 14 farms to evaluate the occurrence of <i>netB-</i>positive <i>C. perfringens</i> and the impact of infection in Italian poultry flocks. Environmental samples (<i>n</i> = 117) and 50 carcasses were screened by microbiologic and molecular methods. Microbiologic investigations yielded 82 <i>C. perfringens</i> isolates. DNA was extracted from all samples and screened for α-toxin and NetB encoding genes by real-time PCR. The <i>C. perfringens</i> α-toxin gene was detected in 151 of 167 extracts (90.4%), and 31 of 151 (20.5%) were <i>netB</i> gene positive also. Sixteen isolates from a turkey flock with mild enteric disorders were also <i>netB</i> positive, demonstrating their occurrence not only in broiler but also in turkey flocks. A pulsed-field gel electrophoresis protocol was optimized to evaluate the diversity among isolates and revealed high genetic heterogeneity. The complete NetB toxin-coding gene of 2 <i>C. perfringens</i> isolates from turkey and broiler flocks were analyzed and showed very high relatedness with analogous sequences worldwide.