Detection of Clostridium difficile toxin by enzyme immunoassay, tissue culture test and culture

Clostridium difficile infection

The spore-forming anaerobe Clostridium difficile has become a serious enteropathogen. Changes in the composition of natural intestinal flora, mainly due to antibiotic therapy, permit its colonization of, and multiplication in, the colon. The disease is caused by (entero)toxin A and (cyto)toxin B, and infection ranges from asymptomatic carrier state and mild diarrhea to pseudomembranous colitis. The clinical diagnosis is made by observing inflammatory, sometimes bloody, diarrhea and by the colonoscopic detection of epithelial necrosis, ulceration, and, in the advanced state, pseudomembrane formation. The laboratory supports the diagnosis by detecting toxin A and/or B by an enzyme-linked immunoassay with high specificity, but sometimes less sensitivity than with the cytotoxin assay in tissue culture cells. Fecal leukocytes or fecal lactoferrin may be found. Culture for the isolation and identification of toxigenic C. difficile is time consuming but necessary for epidemiological studies. Polymerase chain reaction (PCR) tests have been tested for detection of the toxin B gene directly in stool. Therapy consists of stopping all systemic antibiotic treatment and the use of oral metronidazole or vancomycin. There may be more relapses after vancomycin therapy, and the increasing vancomycin resistance of Enterococcus is worrisome. Prevention, especially of nosocomial spread, requires isolation and enforced handwashing. For epidemiological studies, the bacteria can be typed by molecular DNA analyses, including PCR, protein electrophoresis, and immunological tests.

Culture of intestinal biopsy specimens and stool culture for detection of bacterial enteropathogens in patients infected with human immunodeficiency virus. The Berlin Diarrhea/Wasting Syndrome Study Group

The diagnostic yields of stool cultures and biopsy specimens for the detection of enteric bacterial pathogens in 213 human immunodeficiency virus-infected patients were compared. Forty-five percent (19 of 42) of the pathogens were detected exclusively by stool culture, 2% (1 of 42) of the isolates were detected exclusively by culture of biopsy specimens, and 53% (22 of 42) were detected by both methods. Repeated stool cultures remain the most important means of diagnosing enteric bacterial pathogens, which were encountered in 20% (40 of 213) of all patients. The additional culture of biopsy specimens should be reserved for patients with suspected mycobacteriosis.