Comparison of two toxins produced by Clostridium difficile

Abstract

Clostridium difficile was shown to produce a toxin which could be biochemically separated from the previously described cytotoxin of the same organism. The two proteins differ in biological activity and physical properties. Antiserum prepared to the second toxin does not neutralize the biological activity of the cytotoxin, and immunological cross-reactivity could not be demonstrated. However, some relationship may exist between the two toxins, since the newly described toxin degrades on polyacrylamide electrophoresis into two molecules, one of which appears to migrate with the band of purified cytotoxin. We suggest that this newly described toxin be designated toxin A until its primary biological activity and physical relationship to cytotoxin is determined. This toxin is active in biological assays of enteric disease and may play an important role in C. difficile-induced colitis. Previous observations in several laboratories implicate Clostridium difficile as the etiological agent of pseudomembranous colitis, a serious disease which is usually a complication of antimicrobial therapy. This conclusion is supported by studies showing that stools from patients with pseudomembranous colitis contain a cytotoxin which is neutralized by clostridial antitoxins, that cultures of specimens yield C. difficile, and that these isolates produce a similar or identical cytotoxin in vitro (2, 3, 6, 12-14, 18, 19, 22). Also, intracecal injection of cell-free supernatant of stool or broth culture of C. difficile produces lesions similar to those of pseudomembranous colitis in experimental animals (2, 4). Recent studies from several groups indicate that stools from 90 to 95% of patients with pseudomembranous colitis have both the cytotoxin and C. difficile (2, 12, 16). These observations have provided the impetus for several groups to purify, characterize, and study the mechanism of action of C. difficile cytotoxin (1, 15, 23, 26). In this report, we present evidence that C. difficile produces another toxin which elicits positive responses in biological assays of enteric disease. Our findings suggest that this second toxin may play an important role in the clinical symptoms and pathological changes ascribed to C. difficile. MATERIALS AND METHODS Culture preparation. For toxin purification, C.

Production of an enterotoxin different from toxin A by Clostridium difficile

“…Clostridium difficile, the causative agent of antibiotic-associated colitis in man and experimental animals [1][2][3], is known to produce two toxins designated toxin A and B [4][5][6]. Both are cytotoxic for tissue culture cells, although toxin B is 1000-fold more potent than toxin A in the assay [7].…”

Identification and molecular cloning of a 70 kDa species-specific antigen common to Clostridium difficile

“…Clostridium difficile, a Gram-positive anaerobic spore-forming organism, is recognised as the major cause of pseudomembranous colitis and is implicated in antibiotic-associated colitis and diarrhoea [1,2]. The pathogenicity of the organism is related to the production of an enterotoxin, toxin A, and a potent cytotoxin, toxin B [3,4]. The diagnosis of C. difficile-associated disease depends on the isolation and identification of the organism and/or the demonstration of toxins in faecal specimens of patients.…”

Cytotonic effect of Clostridium difficile enterotoxin on Chinese hamster ovary cells

“…C. difficile causes antibiotic-associated diarrhea in humans and animals [1][2][3][4] and produces at least two kinds of toxin; one of the toxins (toxin A, or enterotoxin) produces an intestinal fluid response, whereas the other (toxin B or cytotoxin) is more active on tissue-cultured cells [5][6][7]. The roles of the two toxins in the pathogenesis of antibiotic-associated diarrhea are still not clear [8].…”