Cryptococcal meningitis: diagnostic value of cryptococcal antigen in cerebrospinal fluid

In three previously reported cases of cryptococcal meningitis, the only laboratory evidence for this diagnosis was the presence of cryptococcal antigen in the cerebrospinal fluid (CSF). Three additional patients had chronic meningitis and repeatedly negative CSF cultures and had cryptococcal antigen demonstrated in the CSF. In our patients, the diagnosis was further supported by the complete recovery after amphotericin B therapy in two and the demonstration of Cryptococcus neoformans in the meninges at autopsy in the third. In certain patients with chronic meningitis, the detection of cryptococcal antigen in the CSF may be the only means of establishing a diagnosis during life. In such patients, if cryptococcal antigen is present in the CSF in a titer of larger than or equal to 1:8, antifungal therapy should be initiated, pending results of other diagnostic studies.