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Spring 1997 Newsletter

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Multiplex Polymerase Chain Reactions (PCR) for Clostridiumperfringens (alpha, beta, epsilon, iota and entero toxins) Genotyping

This new test is available at ADDL Bacteriology Lab. The cost is $15 per isolate. Each isolate will be tested against four typing toxins: type A Clostridium perfringens contains only alpha toxin, type B, alpha, beta and epsilon toxins, type C, alpha and beta toxins, type D, alpha and epsilon and type E, alpha and iota toxins. In addition to the detection of typing toxins, each isolate will be tested for the presence of enterotoxin. Thus, the results can be "Type A" or "Type Aenterotoxigenic," or "Type B," or "Type B enterotoxigenic," etc.

Clostridium perfringens, a common inhabitant of the gastrointestinal track of warm blooded animals, as well as terrestrial, marine and aquatic environments may be the most widely occurring bacterial pathogen.  It causes several forms of enteric disease, including fetal enterotoxemias in domestic animals and human. The virulence of the organism is associated with the production of as many as 17 exotoxins and four of these (alpha, beta, epsilon and iota), the so-called typing toxins, form the basis for division of species into 5 toxigenic types.

Detection of the major toxins in clinical specimens has been one item of key evidence in the diagnosis of clostridial enteritis. Enterotoxin is considered by many to be a virulence attribute in animal strains of C. perfringens and it may be produced by any of the 5 typing strains. Dependence on in vivo methods for toxin detection has become a limiting factor in routine diagnosis. In vitro tests using molecular approaches to identify toxin genes and/or immunological assays to detect toxins have been established in a few labs in the United States. The key question is can the genotyping be correlated with the phenotyping?

Based on the report of Dr. Glen Songer at the Annual AAVLD meeting, genotyping determined by the multiplex PCR is 99-100% correlated with the phenotyping. Actually, one of the phenotypedstrain was found to be incorrect based on the genotyping. Dr. Songer and co-workers also found that 95% (N=344) of C. perfringens isolated from domestic animal and human are type A, and 12.8% of these contains enterotoxin. The remaining 5% of isolates he studied were types B, C, D or E. However, the report didn't address the correlation of toxin levels in the gut or feces of infected animal to the genotypes of the isolates. This may be due to the lack of accurate and cost effective test for clostridial toxin detection.   (However, please consult the lab if you need to test for toxins.) In January, a total of 34 cases have been genotyped by ADDL.  Twenty seven were found to be type A(~80%), three type E, two type C and one type A enterotoxigenic. There was one untypable culture.

- prepared by ChingChingWu, DVM,PhD




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Fax: 765-494-9181

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Phone: (812) 678-3401
Fax: (812) 678-3412

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