A laboratory-based study to identify and speciate non-tuberculous mycobacteria isolated from specimens submitted to a central tuberculosis laboratory from throughout KwaZulu-Natal Province, South Africa

Abstract

Background. Non-tuberculous mycobacteria (NTM) are important environmental pathogens capable of causing a spectrum of infection. The different species exhibit varied geographical prevalence worldwide. Identification of the infecting organism may be helpful in determining the clinical significance of the isolate.

Objective. To describe the spectrum of NTM isolated from clinical specimens received at the National Health Laboratory Service central tuberculosis laboratory in KwaZulu-Natal Province, South Africa.

Method. In a laboratory-based prospective study, 200 suspected NTM were randomly selected over a period of 1 year and identified to species level using a commercially available DNA strip assay (GenoType Mycobacterium, CM/AS; Hain Lifescience, Germany).

Results. Of the 200 suspected NTM, 133 (66.5%) were confirmed to be NTM by the molecular test. The most frequently isolated NTM species were Mycobacterium intracellulare (45.9%), M. avium subspecies (11.3%), M. gordonae (6.0%) and M. kansasii (4.5%).

Conclusion. It is important for laboratories to document the local spectrum of NTM because of the geographical variation in the different NTM species isolated. Although molecular tests for identifying NTM are relatively expensive, they have the advantage of providing rapid and accurate identification of the various NTM species.