Non-tuberculous mycobacterium isolations from tuberculosis presumptive cases at the National Tuberculosis Reference Laboratory Kenya, 2018–2019

Abstract

Background: Mycobacterial pathogens are among the top causes of diseases in humans. In Kenya, incidences of Non-Tuberculous Mycobacteria (NTM) species have steadily been on the increase. Most NTMs are resistant to first line treatment of tuberculosis and have a challenge in timely and accurate diagnosis. Misdiagnosis has led to prescribing anti-tuberculosis regimens to patients suffering from NTM. We aimed to determine the most prevalent Non-Tuberculous Mycobacterium in Kenya. Methods: We reviewed records from the National Tuberculosis Reference Laboratory (NTRL) Laboratory information management system (LIMS) between January 2018 and December 2019 for the patients on surveillance. All isolates were cultured in Mycobacterial Growth Indicator Tubes (MGIT) and incubated for detection using BACTEC™ MGIT™ system. Those with negative acid-fast bacilli (AFB) growth and negative for Mycobacterium Tuberculosis Complex Species (MTBC) protein-MPT64 were suggestive of NTM infections, which were sub-cultured in MGIT and characterized using Line Probe Assay (LPA) GenoType® MTBDR CM/AS. Descriptive and bivariate analysis was done. Results: Of the total 24,549 records reviewed, 167(0.7%) were NTM isolates.  Males comprised of 74.2% (124/167), and the mean age was 42 years (SD±16), age group 35-44 years had the highest NTM at 26.3% (44/167). Nairobi had 12.6% (21/167), Mombasa 10.8% (18/167), Kilifi and Meru each had 7.8% (13/167). Eleven isolated species comprised of Mycobacterium intracellulare 35.3% (65/167), M. fortuitum at 27% (48/167), and M. scrofulaceum at 10.2% (17/167). Previously treated patients had higher NTM [63.5% (106/167)] than Drug-resistant follow-up patients [26.9% (45/167)]. Coinfection with HIV was at 27.5% (46/167). Conclusion: Previously treated patients should have an additional screening of NTMS, and drug susceptibility testing should be done before initiation of treatment.