A comparative evaluation of the Gram stain and India ink stain for the rapid diagnosis of cryptococcal meningitis in HIV infected patients in Durban

摘要

Background: Cryptococcal meningitis is the most common systemic fungal infection in HIV infected patients. The India ink stain is currently recommended for the microscopic detection of cryptococci. There is very little published data on the utility of the Gram stain. We therefore, undertook a comparative evaluation of the Gram stain and India ink stain for the rapid diagnosis of cryptococcal meningitis in HIV infected patients.Methodology: Gram and India ink stains were performed on 90 cerebrospinal fluid (CSF) samples. Culture was used as the gold standard.Results: Of the 83 culture positive samples, the India ink was positive in 84% [70 /83] and the Gram stain was positive in 89% [74/83]. The specificity for both methods was 100%.Discussion: Our results indicate that the Gram stain is a simple, cheap and reliable method for the diagnosis of cryptococcal meninigitis. It is routinely performed on all CSF samples received in the laboratory and would therefore detect cryptococci in cases where the clinician had not specifically requested the India ink stain. Although the Gram stain is the most widely used stain in microbiology laboratories, it is not routinely recommended for the laboratory diagnosis of cryptococcal meningitis.Conclusion: We therefore suggest that the Gram stain be included as part of the routine workup for cryptococcal meningitis, particularly in resource-poor countries. However, further studies are required to verify our results.