Clostridium perfringens is a Gram-positive anaerobic spore-forming bacterium known to be the most widely distributed pathogen in nature. It is commonly found in the environment (in soil and sewage) and in the intestines of animals and humans as a member of the normal flora.
C. perfringens has been shown to be a cause of human diseases such as gas gangrene (clostridial myonecrosis), food poisoning, necrotizing enterocolitis of infants, and enteritis necroticans (pigbel) . It is also the causative agent of animal diseases such as lamb dysentery, ovine enterotoxemia (struck) and pulpy kidney disease of sheep, and other enterotoxemic diseases of lambs and calves. Isolates of C. perfringens can be divided into five types (A to E) based on the particular extracellular toxins which they produce . Each of these toxin types are responsible for specific disease syndromes
C. perfringens diseases are generally mediated via the production of extracellular enzymes or toxins, with the exception of human food poisoning, which involves a sporulation- specific enterotoxin. C. perfringensC. perfringens strain involved, and each type of toxin induces a specific syndrome. Therefore, the correct identification of C. perfringens pathovars is critical for epidemiological studies and for the development of effective preventative measures, including vaccination.
Most of the virulence genes from C. perfringens have been characterized (Table 2 ). The genes encoding \u03b1, \u03b8-toxin, \u03ba-collagenase and \u03bc-hyaluronidase are located on variable regions of the chromosome near the origin of replication. Only the nanH and nanI genes, encoding neuraminidases, are localized on a conserved region. In contrast, the genes encoding \u03b21-toxin, \u03b22-toxin, \u03b5-toxin, \u03b9-toxin, \u03bb-protease are located on plasmids of various sizes (55-140 kb). The location of most of the toxin genes on extrachromosomal elements is probably responsible for the diversity of C. perfringens A.
Perfringens food poisoning is the term used to describe the common foodborne illness caused by C. perfringens type A. The actual cause of poisoning by C. perfringens is temperature abuse of prepared foods. Small numbers of the organisms are often present after cooking and multiply to food poisoning levels during cool down and storage of prepared foods. C. perfringens cells sporulate in the small intestine and generate large quantities of enterotoxin. This can result, 12 to 24 h later, in intense nausea, diarrhea, and, more rarely, vomiting, with the occasional fatality amongst the elderly and debilitated. C. perfringens, Type C causes the more serious Enteritis necroticans (pigbel) in humans. does not invade healthy cells but produces various toxins and enzymes that are responsible for the associated lesions and symptoms. The toxins produced depend on the