Detection of mannan from sera of cancer patients with and without candidiasis by biotin-streptavidin enzyme immunoassay

Abstract

Borth cultures (1-3×107cfu/ml) of Candida albicans and C. tropicalis showed mannan concentrations ranging from 4.8 to 23 ng/ml, whereas broth cultures of Candida species excluding C. albicans and C. tropicalis showed mannan concentrations of 0.1ng/ml or less. In addition, sonicated and lyophilized Candida antigens of C. albicans and C. tropicalis had mannan concentrations ranging from 50 to 150ng/μg, whereas antigens of Candida species excluding C. albicans and C. tropicalis had mannan concentrations of 10 ng/μg or less.Of 202 cancer patients, 107 died during hospital stay. Autopsy was performed in 55 patients, and invasive fungal infections were found in 25 patients. Mannan antigenemia (>1ng/ml) was detected in all patients with systemic candidiasis (8 cases), and in 3 patients with invasive gastrointestinal candidiasis (6 cases). Of 8 patients with probable invasive candidiasis, 7 patients had mannan antigenemia. Blood cultures were positive for Candida species in 7 patients, and antigenemia antedated the positive blood cultures by 5 to 19 days in 3 patients. On the other hand, 2 of 180 patients without candidiasis were positive for serum mannan. In 48 healthy adults, none of the sera had mannan concentrations of 0.5 ng/ml or greater.Clinical evaluation of the detection of mannan (>1ng/ml) for 22 patients with invasive and probable invasive candidiasis was made, and the sensitivity and specificity of serum mannan were 82% and 99%, respectively. Thus, monitoring of high risk patients for serum mannan is useful to diagnose invasive candidiasis early in its course.