Comparison of Antigen Detection and Nested PCR in CSF Samples of HIV Positive and Negative Patients with Suspected Cryptococcal Meningitis in a Tertiary Care Hospital

Abstract

Introduction: The cases of cryptococcal meningitis and other forms of cryptococcosis have increased in recent time and the present scenario of the condition with significant morbidity and mortality is actually posing a serious threat to the community, so an early and prompt diagnosis is necessary to prevent serious complications and thus improving the overall disease outcome.

Aim: Comparison of diagnostic efficacy of nested Polymerase Chain Reaction (PCR) with Latex Agglutination Test (LAT) in the Cerebro Spinal Fluid (CSF) samples of the cases of meningitis in HIV positive and negative cases.

Materials and methods: We have compared the diagnostic efficacy of Latex Agglutination Test (LAT) with nested Polymerase Chain Reaction (PCR) in 200 Cerebrospinal Fluid (CSF) samples, including 14 HIV positive also, in the cases of suspected cryptococcal meningitis. Nested PCR was done in all cases reporting positive by LAT and results were then compared with that of India ink and culture on Sabouraud Dextrose Agar (SDA), and the isolates were further identified by urease, nitrate and sugar assimilation tests.

Results: Of the 200 cases, including 14 HIV positive, LAT was positive in 46 cases while 154 were negative. Out of these 46 LAT positive cases, nested PCR was positive in 40 cases only, while culture and India ink was positive in 38 and 33 cases respectively. Majority of the cases, 30 (65.2%) were between age group 21-50 years, while 2 (4.3%) in 0-20, and 14 (30.4%) in 51-80 years age group.

Conclusion: Although negative staining like India ink and nigrosin are most widely used techniques, but these suffer with subjective error. Rapid method like LAT is available but it always has the scope of false positive and negative results. In such cases nested PCR can help in establishing final diagnosis.

Keywords: Antigenimia; CALAS Test; Cryptococcosis; LAT.

[Table/Fig-3]:

1^St PCR amplification. Lane 1DNA Marker VIII, lane 12 Positive control - C. neoformans, lane 11 Negative control - ATCC Candida albicans 90028, lanes 2, 3, 4, 5, 6, 7 Negative CSF samples, lanes 8, 9, 10 Positive CSF samples (415bp).

[Table/Fig-4]:

2^nd PCR amplification (nested PCR). Lane 1 DNA Marker VIII, lane 11 Positive control - C. neoformans, lane 12 Negative control - ATCC Candida albicans 90028, lanes 2, 3, 4, 5, 6, 7 Negative CSF samples, lanes 8, 9, 10 Positive CSF samples (116bp).