Comparison of TrueNat polymerase chain reaction and mycobacterium growth indicator tube culture in the diagnosis of pulmonary and extrapulmonary tuberculosis
Citation Information :
Valsan PM, Sudarasana J. Comparison of TrueNat polymerase chain reaction and mycobacterium growth indicator tube culture in the diagnosis of pulmonary and extrapulmonary tuberculosis. 2022; 24 (1):21-25.
Many diagnostic tests are available for tuberculosis (TB), from light microscopy, fluorescent microscopy, solid culture, liquid culture (Mycobacterium growth indicator tube [MGIT] culture) to molecular methods. The turnaround time and sensitivity of these tests vary depending on the procedure and principle involved. Based on this background, we compared the results of TrueNat Mycobacterium TB (MTB) Polymerase chain reaction (PCR) and MGIT culture in different clinical samples. A retrospective study was conducted in a tertiary care Hospital Kozhikode, Kerala from December 2018 to October 2021. A total of 431 samples (342 extrapulmonary and 119 pulmonary) were received in the laboratory for both TrueNat MTB PCR and MGIT culture. The samples sent for a single test and/or inadequate volume of samples for both tests were excluded from the study. In extrapulmonary samples, TrueNat MTB PCR and MGIT culture were positive for 31 (9%) samples. MGIT culture was positive in 48 (14%). Seventeen samples (5%) were positive only by MGIT culture. The sensitivity and specificity of PCR in extrapulmonary TB samples are 65% and 70%, respectively. Eighteen pulmonary samples (15%) were positive by both TrueNat PCR & MGIT culture. MGIT culture was positive in 20 (17%) pulmonary samples. Two pulmonary samples were positive by MGIT culture only. The sensitivity and specificity of PCR in pulmonary samples are 90% and 96%, respectively. Accurate diagnosis followed by prompt treatment is vital for the elimination of TB from our country by 2025. PCR is found to be a very rapid method in the early diagnosis of TB. However, culture still remains the gold standard test for the diagnosis.
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