Evaluation of Caretb real time PCR for rapid detection of Mycobacterium Tuberculosis in pulmonary specimens

Rapid diagnosis of tuberculosis (TB) is one of the cornerstones for global TB control as it allows early epidemiological and therapeutic interventions. The slow growth of the tubercle bacillus is the greatest obstacle to rapid diagnosis of the disease. Newer molecular methods which are based on nucleic acid amplification (NAA) of different targets, aim to identify the M. tuberculosis complex in 6–8 hours. In this study, we assessed the performance of careTB Assay, a Real Time based Polymerase Chain Reaction (PCR) for identification of IS6110 insertion sequence which is specific for Mycobacterium Tuberculosis Complex (MTC). Sputum specimens were collected from 100 patients with suspicion of pulmonary tuberculosis and tested for the presence of MTC using careTB kit. The results were compared against MTB culture. The sensitivity, specificity, positive predictive value, and negative predictive value of TB PCR were 92.98%, 88.37%, 91.38% and 90.48% respectively. PCR correctly identified MTC in four of the smear negative/culture positive samples indicating high sensitivity of the assay. Four of the culture positive MOTT specimens were found to be negative by IS6110 PCR which is highly specific for MTC group of organisms. careTB test is simple, easy to perform and delivers the results in lowest possible turnaround time. Its sensitivity, specificity, and positive predictive value are satisfactory.