Tuberculosis (TB) is one of the deadliest diseases worldwide, caused by members
of Mycobacterium tuberculosis complex (MTBC), commonly by Mycobacterium
tuberculosis (Mtb) and Mycobacterium bovis. In Malaysia, Sabah is one of the
states of public health concern with the highest TB cases. Clinical presentations
of TB and non-tuberculous mycobacteria (NTM) lung disease are similar, and
mycobacteria appear to be identical under standard diagnosis with sputum smear
microscopy, causing difficulty to diagnose TB. Identification of Mycobacterium
species is essential for effective management of mycobacterial diseases treatment
and their control strategy. Thus, this study aimed to identify the Mycobacterium
species from suspected TB patients in Sabah using molecular methods. Sputum
samples (n=595) were screened with GeneXpert MTB/RIF (Xpert), and positive TB
samples (n=67) were processed and cultured in BACTEC MGIT. Forty-five isolates
were successfully recovered in MGIT and characterisation of the mycobacterial
isolates using PCR and/or sequencing with rpoB, RD9, hsp65, and 16S rRNA genes
confirmed the presence of Mtb in 41 samples, and four non-mycobacteria, i.e.
Microbacterium laevaniformans, Streptomyces sp., Streptomyces misionensis and
Gordonia sp. These non-mycobacteria isolates showed negative results when
tested directly with Xpert. In conclusion, Mtb is the predominant species of MTBC
circulating in Sabah. The presence of non-mycobacteria in this study was due to
bacterial contamination in MGIT, not bacterial cross-reactivity in Xpert, implying
the high sensitivity and specificity of Xpert for diagnosis of TB