[No abstract submitted] / Science, Faculty of / Microbiology and Immunology, Department of / Graduate

Indiana University-Purdue University Indianapolis (IUPUI) / Clostridium perfringens is an important human pathogen known to cause a range of diseases including diarrhea, necrotizing bowel disease and gas gangrene. Though potentially pathogenic, this microorganism is commonly identified in the fecal microbiota of healthy individuals. The major clinical findings associated with C. perfringens diseases are linked to production of potent toxins. In 1997, Gibert et al. identified a new toxin, the beta2 toxin, from a C. perfringens strain from a piglet with necrotic enteritis. Subsequently, this new beta2 toxin gene (cpb2) has been identified in C. perfringens from dogs, horses, and other animals. The principal objective of this investigation was to study cpb2 and the beta2 toxin in C. perfringens isolates from human sources. The C. perfringens isolates were grouped into three different populations: 1) fecal samples from patients suspected of having C. perfringens gastrointestinal illnesses (e.g. antibiotic-associated diarrhea or colitis), 2) extraintestinal specimen sources (e.g. wounds, abscesses, blood cultures), 3) a control group of isolates from healthy volunteers. Results of studies using different PCR methods and nucleotide sequencing revealed that cpb2 was present in the genome of isolates from all populations, and that the genetic variation between cpb2 from the different C. perfringens isolates was greater then expected. Using western blotting techniques, it was found that the beta2 protein was not expressed by all cpb2 positive C. perfringens isolates. Finally, different variants of cpb2 were cloned into E. coli, and the recombinant beta2 protein used in cell cytotoxicity assays. Results from these assays demonstrated that recombinant beta2 proteins caused a range of cellular damage at different levels of protein concentration and different lengths of time. Our results from these experiments provided new information regarding cpb2 in C. perfringens isolates from human sources; as well as on the range of variation of cpb2 genes, differences in beta2 toxin expression, and differences in the effects of recombinant beta2 toxin on enterocytes. This information could help to explain differences in virulence between C. perfringens isolates, differences in diseases and disease severity.

Thesis (Ph. D.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 109-118). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Missouri--Columbia, 2001. / "May, 2001." Typescript. Vita. Includes bibliographical references (leaves 148-155). Also available on the Internet.

Although progress has been made in the last decade in understanding the causes of colitis in horses, perhaps 60% of cases of fatal colitis in horses have no known cause. The role of type A Clostridium perfringens strains was evaluated in this study. Fecal samples from 55 horses (43 adults, 12 foals) with colitis were cultured for Clostridium difficile, Salmonella, and C. perfringens. Feces were also tested for C. difficile toxins A/B and C. perfringens toxins (alpha [CPA], beta2 [CPB2], enterotoxin [CPE]) using enzyme-linked immunosorbent assays (EIA). All fecal samples were negative for Salmonella. Clostridium perfringens and C. difficile were isolated from 40% and 5.4% of samples, respectively. No CPE was detected but 36.4% and 18.2% of animals were positive for CPA and CPB2 toxin, respectively. Subsequently, five C. perfringens isolates per fecal sample were genotyped and the supernatants of each of these isolates were evaluated for toxicity. None of the isolates were cpe, netB or tpeL positive, but atypical cpb2 and consensus cpb2 were identified in 13.6% and 3.6% isolates, respectively. All equine C. perfringens isolates showed mild toxicity effects compared to CPB producing C. perfringens positive control. Based on this study population, there was no evidence that C. perfringens had an important role in equine colitis. / Equine Guelph and Natural Sciences and Engineering Research Council

Thesis (M.S.)--University of Wisconsin--Madison, 1971. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Techn. University, Diss., 2002--München.

Thesis (Ph. D.)--University of Wisconsin, 1965. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis--Wisconsin. / Includes bibliographical references (leaves 121-134).

Thesis (M.S.)--University of Wisconsin--Madison, 1963. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 95-103).