Real-World Performance of Diagnostic Testing for Coccidioidal Meningitis in Initial Sampling of the Cerebrospinal Fluid

Early diagnosis and treatment are essential for improving outcomes of coccidioidal meningitis. While the detection of IgG by serologic testing of the cerebrospinal fluid (CSF) has been a mainstay of diagnosis for years, the diagnosis of coccidioidal meningitis in clinical practice can be very challenging due to suboptimal sensitivity of laboratory tests. We reviewed the results of CSF diagnostic test results from 110 patients with proven, probable and likely coccidioidal meningitis from 1989-2024. One hundred four patients were diagnosed with coccidioidal meningitis on the initial CSF examination. The positivity rate of the first CSF testing was 89.1% (n = 64) for IgG by enzyme immunoassay, 62.2% (n = 98) for IgG by immunodiffusion, and 70.2% (n = 104) for IgG by complement fixation, 4.4% (n = 90) for fungal culture, 18.8% (n = 69) for polymerase chain reaction, and 33% (n = 21) for Coccidioides antigen. The non-specific fungal marker 1,3-β-D-glucan was positive in the CSF in 70.4% (n = 27) of samples. Contrasted brain magnetic resonance imaging identified leptomeningeal enhancement in 53.1%. Optimal detection of coccidioidal meningitis requires a combination of diagnostic modalities.