Prevalence of netB among some clinical isolates of Clostridium perfringens from animals in the United States
ABSTRACT A previously unknown pore forming toxin, called NetB toxin, which is produced by some Australian strains of Clostridium perfringens has recently been reported. This toxin was reported to be critical to the development of the disease necrotic enteritis, in chickens. To investigate the occurrence of the toxin gene (netB) in non-Australian C. perfringens strains, one hundred and six American isolates of C. perfringens were examined. Ninety-two isolates were from chickens, and 14 were from cattle. The netB gene was found in 14 isolates from chickens (7 from chickens with necrotic enteritis, and 7 from unrelated chickens with no evidence of necrotic enteritis). The netB gene was also detected in an isolate recovered from a 3-year-old cow with liver abscesses. The products of all positive netB PCR reactions were sequenced, and these showed 100% nucleotide identity to the netB sequence published in GenBank. Five isolates which had been recovered from five chickens with necrotic enteritis (from four flocks) were netB negative. An additional 24 isolates recovered from one of these lesioned chickens were also netB negative. The present study represents the first study of C. perfringens isolates outside Australia for netB, and the first identification of netB in an isolate from a species other than chickens. The results indicate that the role of NetB in the induction of necrotic enteritis needs to be further investigated, by determining the disease producing capability of both netB positive strains recovered from normal chickens, and netB negative strains recovered from chickens with necrotic enteritis.
SourceAvailable from: dspace.lib.uoguelph.ca
[Show abstract] [Hide abstract]
ABSTRACT: The sialidase activity and genetic diversity of 22 Clostridium perfringens strains isolated from chickens with necrotic enteritis were determined. Sialidase activity was detected in 86.4 % of the strains. All C. perfringens showed a high value of similarity (>96 %), and they were grouped into seven clusters clearly separated from the other reference bacterial strains. From these clusters four patterns were defined in accordance with their phenotypic (sialidase production and antibiotic resistance profile) and genotypic (presence of nanI and nanJ genes) characteristics. Our results showed heterogeneity among strains, but they were genotypically similar, and it is suggested further studies are needed to better understand the pathogenesis of necrotic enteritis.Current Microbiology 11/2014; 70(3). DOI:10.1007/s00284-014-0722-5 · 1.36 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Necrotic enteritis caused by Clostridium perfringens is the common economic losses in poultry industries worldwide. However, the exact mechanism behind the pathogenesis of C. perfringens is poorly understood. Historically, the alpha-toxin produced by C. perfringens has been regarded as the major virulence factor for the development of necrotic enteritis in chickens. Recent studies of some researchers indicate that the role of alpha-toxin on the pathogenesis of necrotic enteritis has been called into question. It has been reported that alpha toxin produced by C. perfringens does not show a positive correlation with necrotic enteritis. Furthermore, a new toxin of C. perfringens, designed necrotic enteritis toxin B (NetB), was identified and suggested to be critical to the development of necrotic enteritis in experimental chick-ens. The supporting data showed that the presence of netB-gene in C. perfringens strains was shown to be higher in samples from outbreaks of necrotic enteritis than in samples from non-lesion of necrotic enteri-tis flocks. These indicate that NetB is associated with the pathogenesis of necrotic enteritis in chickens. However, some researchers had reported the induction of necrotic enteritis by netB-negative C. perfrin-gens strains, questioning the clear cut correlation between necrotic enteritis and NetB. Therefore, the role of other factors that induce necrotic enteritis in chickens needs to be further investigation.