Diagnostic value of Cobas Amplicor MTB and Rotorgene Real Time PCR for tuberculous meningitis: A six-year retrospective study

Abstract

Objective: Tuberculous meningitis (TBM) is the most severe and lethal form of tuberculosis (TB).Bacteriologic confirmation of TBM is difficult and slow. Therefore, most patients receive antituberculosis treatment based only on clinical and cerebrospinal fluid (CSF) characteristics. Rapid diagnosis of TBM is important to decrease morbidity and mortality. The aim of the study was to demonstrate that COBAS Amplicor MTB and Rotorgene Real Time (RT) PCR is a rapid method of diagnosing TBM before and after initiating anti-tuberculosis treatment. Methods: A retrospective study was conducted between December 2002 and January 2009 in 468 patients with suspected TBM. Clinical specimens were collected from different hospitals in Ankara. All specimens were evaluated by smear microscopy and culture methods with Lowenstein-Jensen (LJ) and MGIT culture system. Results: Using culture results as a gold standard, the sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) were 71.0%, 98.8%, 97.8% and 75.0%, respectively, for COBAS Amplicor MTB and 80%, 98.9%, 99.0% and 80.0%, respectively, for Rotorgene RT PCR. Statistical analysis showed no significant differences between the COBAS Amplicor MTB and Rotorgene RT PCR (p≥0.05). All isolates were susceptible to isoniazid, rifampin, streptomycin, and ethambutol with proportion method in LJ medium. All isolates were defined as LAM7-TUR by spoligotyping. Conclusion: Retrospective analysis of COBAS Amplicor MTB and Rotorgene RT PCR found that both tests are effective in rapidly diagnosing MTB using CSF. It was concluded that Rotorgene RT PCR test is more sensitive (81.0%) than COBAS Amplicor MTB (71.0%). J Microbiol Infect Dis 2015;5(4): 156-161 Key words: Tuberculous meningitis, COBAS Amplicor MTB, Rotorgene Real Time PCR