Sensitivity and specificity of a latex agglutination test for detection of cryptococcal antigen in meningitis

Abstract

A cryptococcal latex agglutination test (Crypto-La; International Biological Laboratories, Canbury, New Jersey, USA) was evaluated for its ability to detect cryptococcal antigen in cerebrospinal fluid (CSF) specimens obtained from black patients with a clinical diagnosis of meningitis. Of the 445 Gram-stained and bacterial culture-negative CSF specimens routinely tested for cryptococcal antigen, 34 (7,6%) were positive. With the exception of 1 false-positive result, the remaining 33 specimens were obtained from 12 patients in whom the diagnosis of cryptococcal meningitis was confirmed by the isolation of Cryptococcus neoformans. The Crypto-La test gave false-positive results on 1% (4/384) of control CSF specimens tested. Nonspecific agglutination reactions were observed with 1,6% (13/829) of all CSF specimens and 22% (10) of sera tested. The ethylenediaminetetra-acetic heat-extraction method proved reliable in eliminating false-positives and nonspecific agglutination reactions in CSF and serum specimens.