Prevalence of Nontuberculous Mycobacteria in Patients Suspected of Tuberculosis and Drug Resistant Tuberculosis

Abstract

Introduction: Nontuberculous mycobacteria (NTM) are being increasingly recognized as pathogens of importance. NTM cause disease similar to tuberculosis (TB) and are resistant to anti-tubercular drugs, so may present as drug resistant TB (DRTB). There is a lack of data on prevalence of NTM. The present study was aimed to detect the prevalence of NTM in pulmonary specimens of patients suspected of TB/DRTB. Methodology: A total of 18,334 pulmonary samples received in Mycobacteriology laboratory during January 2018 to December 2018 from TB/DRTB suspect patients were cultured on Mycobacteria growth indicator tube (MGIT) 960 and Lowenstein Jenson (LJ) media. The culture and acid fast bacilli (AFB) smear positive samples were subjected to SD Bioline TB-Ag MPT 64 rapid test to differentiate between Mycobacterium tuberculosis (MTB) and NTM. Results: Among 18,334 samples, Mycobacteria were grown in 6653 (36.2%) samples among which 6593 (99.1%) were M tuberculosis and 65 (0.9 %) were NTM, co-infection of MTB and NTM was found in 7.6%(5/65) samples. LJ isolated 6 (9.2%) additional NTM than MGIT while MGIT isolated 23 (35.3%) additional NTM than LJ. Conclusion: Yield for NTM was higher in MGIT than LJ but on LJ separate colonies of NTM and MTB could be seen and helped in identifying co-infection which was missed on MGIT. It is important to repeatedly identify same species from these patients to establish pathogenicity. However, there was very poor follow up from clinician/ patients to submit new sample, which should be stressed upon them.

Keywords

• Drug resistant tuberculosis (DRTB), Mycobacterium tuberculosis (MTB), Nontuberculous mycobacteria (NTM).