Rapid diagnosis of systemic candidiasis using commercial antigen and/or antibody detection kits

Abstract

Systemic candidiasis is a life-threatening disease seen with increasing frequency in hospitalized patients. There has been considerable interest in rapid serological diagnosis, including assays for metabolites and circulating antigens and antibodies. We evaluated a commercially available antigen detection kit (Ramco Labs, Houston, TX) in combination with a commercially obtained antibody test (Allergy Immuno Technologies, Newport Beach, CA). Using the combination for the diagnosis of systemic candidiasis, 81% of patients gave serological indication of infection with one or both methods, confirmed by culture. The antigen titer on its own had a positive and negative predictive value of 80 and 91% using a titer of ⩾1:8 for a positive value and ⩽1:2 for a negative value. Use of high IgM, high IgG and a positive antigen titer ⩾1:8 gave a positive predictive value (PPV) of 99% with a sensitivity of 14% and specificity of 99%. Colonised, patients with candidemia and culture-negative patients were positive in 15, 32 and 27% of cases, respectively. Combined rapid antigen and antibody testing had a negative predictive value of 88%.