CSF staining, testing, and culture If infection is suspected, the centrifuged CSF sediment is stained for the following: Bacteria (Gram stain) Tuberculosis (acid-fast stain or immunofluorescence) Cryptococcus sp (India ink) Larger amounts of fluid (10 mL) improve the chances of detecting the pathogen, particularly acid-fast bacilli and certain fungi, in stains and cultures.