What are the key diagnostic tests for confirming cryptococcal meningitis in an immunocompromised patient?

The key diagnostic tests for confirming cryptococcal meningitis in an immunocompromised patient include cerebrospinal fluid (CSF) analysis with India ink staining, cryptococcal antigen (CrAg) testing, and fungal culture. CSF examination is essential, with India ink staining providing rapid visualization of the encapsulated yeast, although it has limited sensitivity in some cases NICE NG240. The cryptococcal antigen test, performed on CSF and serum, is highly sensitive and specific, making it the cornerstone for diagnosis and often preferred for rapid confirmation Fisher et al. 2021. Fungal culture of CSF remains the gold standard for definitive diagnosis but takes longer to yield results NICE NG240. Additionally, CSF opening pressure measurement during lumbar puncture is important, as elevated pressure is common in cryptococcal meningitis and guides management NICE NG240. Neuroimaging (MRI or CT) may be used to exclude other causes of symptoms or complications but is not diagnostic for cryptococcal meningitis itself Sonneville et al. 2017. Combining these tests ensures accurate and timely diagnosis in immunocompromised patients, who are at higher risk of severe disease Bloch & Bailin 2019.