Diseases produced by <i>Thomasclavelia spiroformis</i>

Clostridium spiroforme , recently renamed Thomasclavelia spiroformis , is a helically-coiled, anaerobic, gram-positive, spore-forming bacillus, which has been associated with spontaneous and antibiotic-associated enteric disease in rabbits and can cause high morbidity and mortality, especially in farmed rabbits. Postulated predisposing factors include altered diet, concurrent infections, weaning, antibiotic treatment, and other factors that can alter normal microbial flora. This enteric disease associated with C. spiroforme is characterized by anorexia, diarrhea, collapse, and often sudden death. The main virulence factor responsible for the disease is C. spiroforme toxin (CST), which is a binary toxin causing cytoskeleton disruption and subsequent cell death. Typical gross findings include cecal dilation with watery and sometimes hemorrhagic contents, edema of the cecal wall, and serosal hemorrhages affecting the cecum and sometimes extending to the ileum and colon. Histologically, necrosis of the superficial epithelium of the small intestine, cecum, and/or colon is observed, with variable leukocytic and fibrinous exudation, and is often accompanied by mucosal or submucosal edema, hemorrhages and congestion. Large numbers of coiled gram-positive bacilli may be observed on the necrotic surface epithelium and in the lumen. A presumptive diagnosis is usually based on gross and microscopic pathology, together with detection of the characteristic coiled bacteria in intestinal smears, and can be confirmed by isolation of C. spiroforme and/or detection of the CST gene by polymerase chain reaction (PCR) assay. However, no commercial tests for the detection of toxin in the feces or intestinal content are currently available. Due to wide intrinsic or acquired antimicrobial resistance, treatment is challenging and preventive strategies are preferred.