Role of Polymerase Chain reaction (PCR) amplifying conserved 5.8S and ITS regions of the cryptococcal DNA in the diagnosis of Cryptococcal meningitis

Abstract

Cryptococcus neoformans, a common fungal pathogen of the central nervous system, results in high morbidity and mortality, unless diagnosed early and specific treatment instituted. The efficacy of the currently available tests for diagnosis (i.e. microscopy and latex agglutination test) are limited. The purpose of the present study was to evaluate a polymerase chain reaction (PCR) test for the diagnosis of cryptococcal meningitis. This cross-sectional prospective study was carried out in a large tertiary care hospital, Pune, India during April 2009 to February 2012. A total of 111 cerebrospinal fluid (CSF) samples were collected from patients with suspected cryptococcal meningitis. All samples were processed for microscopy, culture, antigen detection by Cryptococcal Antigen Latex Agglutination System (CALAS) and PCR using specific primers CN4/CN5. The PCR was evaluated using culture as the gold standard and results compared with those obtained by microscopy and latex agglutination. In the present study 55(49.54%) had laboratory confirmed cryptococcal meningitis (either smear/CALAS/culture/PCR positive). The sensitivity of PCR, antigen detection test and microscopy was 100%, 89.19% and 78.4% respectively while the specificity of these tests was 82.43%, 85.14% & 90% respectively. The positive predictive value of the PCR was 74% and the negative predictive value was 100%. The PCR technique proved to be a rapid and reliable technique for the early diagnosis of cryptococcal meningitis.South East Asia Journal of Public Health Vol.4(2) 2014: 31-35