Disseminated candidiasis: a comparison of two immunologic techniques in the diagnosis.

Eighty-five subjects were tested for the presence of circulating candidal antigen (CAg) and anti-candidal antibody (CAb) using both an enzyme immunoassay (ELISA) and counterimmunoelectrophoresis (CIE). The 72 studied controls included laboratory volunteers; hospitalized patients without evidence of infection; febrile hospitalized patients without evidence of candidiasis; and patients with superficial candidiasis and candiduria. The control subjects were compared with 13 patients with proven disseminated candidal infection (disease prevalence = 15%). The ELISA CAb test was of greater individual sensitivity (92%) in separating patients with systemic candidiasis from all controls combined than the ELISA CAg, CIE CAg, or CIE CAb test (61%, 15%, 69%, respectively). The CIE CAg test, though specific (100%), was insensitive. Sensitivity, specificity, and predictive values were generally enhanced by employing combinations of tests. Sera from patients with disseminated candidiasis were much more likely to yield a positive result by two or more serologic tests than were control sera (p = less than 0.0004). The sensitivity of combinations ranged from 15% to 92%. The specificity of combinations ranged from 21% to 100%. The predictive value positive of combinations test ranged from 40% to 100%. Predictive value negative of combinations ranged from 69% to 98%. Patients with a variety of superficial and deep candidal infections apparently have detectable circulating CAb and/or CAg. The ELISA CAb test was superior to the other tests in identifying patients with disseminated candidiasis. Combinations of serologic tests may be superior to individual tests in the diagnosis or exclusion of serious disease due to Candida albicans.

Discontinuous counterimmunoelectrophoresis in the diagnosis of antibiotic-associated colitis.

Discontinuous counterimmunoelectrophoresis (DCIE) was employed to detect the toxin of Clostridium difficile, etiologic antibiotic-associated colitis (AAC), in bacteria-free stool filtrates from 51 patients with diarrhea. Stool samples from 31 patients contained C. difficile toxin as determined by tissue-culture assay. A positive result was obtained by DCIE in 20 of the 31 patients (65%) and was influenced by the titer of toxin present. When toxin was present by tissue-culture assay in a dilution of less than or equal to 10(-2) (11 samples), DCIE was positive in only 2 (18%). However, DCIE yielded positive results in 18 of the 20 samples (90%) containing toxin titers greater than or equal to 10(-3). The combination of DCIE and sigmoidoscopy of colonoscopy was superior to either alone in the diagnosis of AAC irrespective of the toxin titer. Nine of 11 patients (82%) whose stool samples contained C. difficile toxin in a dilution of less than or equal to 10(-2) were recognized by DCIE, endoscopy, or both. In stool samples containing toxin in titers greater than or equal to 10(-3), no false-negative results were encountered (sensitivity equals 100%). Thus, 29 of 31 patients whose stool samples contained C. difficile toxin were identified when the results of DCIE and endoscopical examination were combined (sensitivity 93.5%). Neither endoscopical examination nor DCIE yielded positive results in the 20 patients whose stool samples lacked C. difficile toxin (specificity equals 100%). DCIE is a rapid, moderately sensitive, and specific method for detecting C. difficile toxin. When DCIE is combined with endoscopy, the vast majority of patients requiring specific therapy for AAC can be identified.