Cryptococcal antigen detection from the urine of AIDS patients

Cryptococcal disease occurs in < or = 10% of AIDS patients. Detection of the capsular polysaccharide antigen of the yeast in spinal fluid or serum is used to establish the diagnosis. In addition, cryptococcal antigen (CAg) analysis is used to adjust treatment and evaluate recurrence of active disease. A specimen such as urine, obtained noninvasively, would be optimum for this evaluation. Urine, cerebrospinal fluid (CSF), and serum for CAg analysis, and culture of urine and CSF, were obtained for 103 sets of specimens from 92 patients. CSF and urine specimens for CAg were analyzed with and without pronase treatment; serum was analyzed with pronase only. Twenty percent (21 of 103) of specimen sets showed CAg from eight patients. In all cases, patients with positive CSF and/or serum titers also had positive urine titers. Titers were always serum > CSF > urine, with ranges of 1: 64-65000; 1: 64-6250; and 1: 2-512, respectively. Pronase treatment did not affect CSF titers, but 14 of 23 titers from urine treated with pronase were at least one dilution higher than those without treatment. No false-positive reactions were observed during the study. CSF cultures were positive from seven of eight, and urine cultures were positive from five of eight patients with CAg. These results indicate that urine can be used as a specimen for detection of CAg in AIDS patients and that use of pronase may increase its sensitivity.