Identification of non-tuberculous mycobacteria from clinical specimens referred to Adama TB reference laboratory, Ethiopia

Abstract

Non-tuberculous mycobacteria (NTM) are opportunistic pathogens that can be acquired from the environment like water and soil. They can cause pulmonary and extrapulmonary diseases in both HIV-positive and HIV-negative individuals. There is no information in Ethiopia on the identity and diversity of NTM in clinical specimens. The aim of this study was to identify and characterize NTM from clinical samples stored between November 2016 to May 2017 at Adama TB reference laboratory. A total of 47 NTM isolates were grouped using Runyon system and speciation was determined using molecular method of GenoType Mycobacterium CM/AS assays. Of the 47 isolates, 24 (51%) were found to be slow growers while 23 (49%) were rapid growers (Group IV). Of the slow growers, 4(16.7%) were photochromogen (Group I), 7(29.2%) scotochromogen (Group II) and 13 (54.2%) non-photochromogen (Group III). NTM species distribution among identified isolates revealed the following groups: M. intracellulare (n=6), M. abcessus/M. immunogenum (n=4), M. gordonae (n=4), M. simiae (n=3), M. fortuitum (type 1) (n=3), M. chelonae/M. immunogenum (n=1), M. scrofulaceum/M. paraaffinicum (n=1), M. avium (n=1) and M. mucogenicum (n=1). The study showed that there are different species of NTM that were known to cause NTM infection as well as disease. Mycobacterium avium complex (Mycobacterium avium and intracellulare 29.2%) was found to be the most common species out of the identified stains. Based on our findings, we suggest that due emphasis should be given to NTM while diagnosing TB and laboratories should be capacitated to properly identify NTM.