Value of Assessing Cryptococcal Antigen in Bronchoalveolar Lavage and Sputum Specimens from Patients with AIDS

Cryptococcus neoformans has become a significant opportunistic pathogen, accounting for 8-10% of infectious complications in patients with AIDS. When encapsulated yeast cells are observed in Giemsa-stained smears of bronchoalveolar washings (BAL), or induced sputum specimens, confirmation as C. neoformans is germane to definitive therapy. We therefore studied 30 BAL and 9 induced sputum specimens for cryptococcal antigen. Of the 30 BAL, 3 specimens were positive for cryptococcal antigen, ranging in titer from 1:4 to 1:256, and 2 of 9 sputum samples were also smear, culture and antigen positive (titer 1:2) for C. neoformans. Of the 34 negative specimens, none of the seven containing Candida species or the one containing H. capsulatum or the one containing P. carinii cross-reacted with cryptococcal anticapsular antibody. Our results indicate that when yeast forms suggestive of C. neoformans are visualized on direct smears of BAL or sputum samples, rapid confirmation as C. neoformans may be achieved by assessment for cryptococcal antigen. A correlation may also exist between antigen titer in respiratory specimens and extent of cryptococcal infection.