Diffusion of ClostridiumperfringensNetB positive strains in healthy and diseased chickens

Abstract

For over 30 years α toxin was considered the key virulence factor responsible for the appearance of necrotic enteritis (NE) in chickens but, recently, a new toxin related to the occurrence of NE, called NetB, has been described. The aim of this work was to evaluate the CP toxin-type and the NetB gene presence in strains collected from chickens affected or not by enteric diseases. 107 strains were tested: 30 isolated from chickens affected by NE, 54 from subjects affected by other enteric pathologies and 22 from healthy animals. All strains resulted toxin-type A and 26.17% of these was positive also for β2 toxin gene. No strains were positive for cpe gene. 27% (29/107) of CP was NetB positive and 93% (27/29) of these was isolated from birds affected by intestinal disorders. 16 NetB positive strains were obtained from chickens affected by NE (16/30), 9 from animals affected by other intestinal disorders (9/54) and 4 from healthy animals (4/22). A significant difference between the number of NetB positive strains isolated from animals affected by NE and healthy chickens has been observed (P=0.014). However, the finding that the 17.4% of strains isolated from healthy chickens was also positive for NetB, confirm that other virulence factors could play an important role on NE appearance.

Prevalence of netB-positive Clostridium perfringens in Italian poultry flocks by environmental sampling

“…Our study offers new insight regarding the prevalence of C. perfringens in Italian poultry flocks. As reported previously, 6 we confirmed the occurrence of netB- positive C. perfringens isolates in broiler flocks, with or without an enteric disorder, suggesting the need for additional environmental factors for disease development. Regarding turkey flocks, although we detected netB- positive C. perfringens isolates, the role of this organism in the pathogenesis of NE is still unclear.…”

“…In Italy, an investigation carried out on 107 C. perfringens isolates recovered from broiler and commercial laying hen flocks revealed that 27% of isolates were netB positive, with 93% of these isolates coming from birds affected by intestinal disorders. 6 On the other hand, a similar study of 106 C. perfringens isolates from turkeys with enteric lesions failed to detect netB -positive isolates. 8…”

Molecular characterization ofClostridium perfringensstrains isolated from diseased turkeys in Italy

“…In contrast, in a previous Italian survey on 107 CP isolates from diseased and healthy chickens, the netB encoding gene was detected in 93% of CP strains isolated from chickens with enteric disorders (Drigo et al, 2009).…”

Clostridium perfringens strains proliferate to high counts in the broiler small intestinal tract, in accordance with necrotic lesion severity, and sporulate in the distal intestine

“…Necrotic enteritis (NE) is a devastating enteric disease, affecting different avian species, including broiler chickens, causing an estimated annual global economic loss of more than US$ 6 billion in the broiler industry (Wade and Keyburn, 2015). Although once the causative Clostridium perfringens strains are introduced into a flock most birds will be infected, not all will develop disease, if any (Drigo et al, 2009). Several studies mention isolation of C. perfringens NetB positive strains from healthy animals, clearly demonstrating a certain fraction of each flock is resistant to NE, also indicated by the lack of disease in a subset of birds in experimental models (Gholamiandekhordi et al, 2006;Drigo et al, 2009;Keyburn et al, 2010).…”