Comparison of latex agglutination and co-agglutination for the diagnosis and prognosis of cryptococcal meningitis.

PURPOSE: To compare a commercially available Latex agglutination test and an in house co-agglutination test for the detection of cryptococcal antigen in cases of chronic meningitis.

METHODS

One hundred and fifty cerebrospinal fluid (CSF) samples from 150 cases of chronic meningitis were tested for the presence of Cryptococcus neoformans by modified India ink, culture and antigen detection by latex agglutination test (LAT) and co-agglutination (Co-A) test.

RESULTS

Thirty-nine cases were positive by one or more tests employed. Antigen detection in CSF by LAT and Co-A was found to be most sensitive (94.9%) while culture was the least (25.6%). Of the two antigen detection methods, Co-A was found to be more sensitive than the LAT, the difference being statistically significant. Initial CSF antigen titres did not have any prognostic significance.

CONCLUSIONS

Co-A for antigen detection is an inexpensive and useful adjunct to direct microscopy and culture for the diagnosis of cryptococcal meningitis, though its usefulness in prognosis needs to be evaluated further.