Prevalence of β2-Toxigenic Clostridium perfringens in Horses with Intestinal Disorders

The incidence of a new, yet unassigned toxin type of Clostridium perfringens containing the genes for the α-toxin and the recently described β2-toxin in horses with intestinal disorders is reported. The study included 18 horses suffering from typical typhlocolitis, 7 horses with atypical typhlocolitis, 16 horses with other intestinal disorders, and 58 horses without intestinal disease. In total, 20 samples of ingesta of the small and large intestines, five biopsy specimens of the intestinal wall, and 74 fecal samples were analyzed bacteriologically. C. perfringens isolates were typed for the presence of the α-, β-, β2-, and -toxin and enterotoxin genes by PCR, including a newly developed PCR for the detection of the β2-toxin gene cpb2. β2-Toxigenic C. perfringens was detected in samples from 13 of 25 (52%) horses with typical or atypical typhlocolitis, with a particularly high incidence in specimens of ingesta and biopsy specimens (75%), whereas only 6 of 16 specimens from horses with other intestinal diseases yielded β2-toxigenic C. perfringens. No β2-toxigenic C. perfringens was found in the samples from the 58 control horses, of which only one fecal sample contained C. perfringens type A. Among the samples from the 15 horses with fatal cases of typical and atypical typhlocolitis 9 (60%) were positive for β2-toxigenic C. perfringens, whereas samples from only 4 of the 10 (40%) animals with nonfatal cases of infection were positive. We found an interesting correlation between the antibiotic-treated horses which were positive for β2-toxigenic C. perfringens and lethal progression of the disease. No C. perfringens strains isolated in this study contained genes for the β- and -toxins and enterotoxin. The high incidence of β2-toxigenic C. perfringens in samples of ingesta, biopsy specimens of the intestinal wall, and feces from horses suffering or dying from typhlocolitis together with the absence of this organism in healthy horses provides strong evidence that β2-toxigenic C. perfringens play an important role in the pathogenesis of typhlocolitis.