Evaluation of latex cryptococcal agglutination test in cryptococcal meningitis.

There is a growing demand for laboratory diagnosis of cryptococcal meningitis, which is partly due to the increasing incidence of AIDS in Thailand. Presently, latex cryptococcal agglutination test (LCAT) is the most sensitive and specific test for laboratory cryptococcal meningitis. However, the test is very expensive and not readily available. LCAT must be developed locally to meet the need in Thailand. Rabbit antibody to C. neoformans was raised and used to sensitize latex particles used in LCAT. The developed LCAT was compared with a reference LCAT. The locally made LCAT was almost identical to the reference LCAT in sensitivity and specificity. It was extensively compared with the culture and India ink examination, in 73 cerebrospinal fluid specimens from cryptococcal meningitis and 155 specimens from other diseases. LCAT was found specific and more sensitive than fungal culture and India ink examination. LCAT is now extensively used in Thailand and recommended by Thai experts for use in all general hospitals. It is a simple, sensitive, specific, rapid and inexpensive tool for both diagnosis, prognosis and follow-up of cryptococcal meningitis.