Evaluation of Non-Tuberculous Mycobacterioses and multidrug resistant Tuberculosis in western Kenya

Abstract

Background: The diagnosis of tuberculosis (TB) in Africa is mostly based on the microscopy. However, both Mycobacterium tuberculosis and non-tuberculous mycobacterioses (NTM) yield positive results in the microscopic detection of acid–fast bacilli (AFB). The conventional anti-mycobacterial chemotherapy is not analogous to the treatment of tuberculosis-like syndromes caused by the NTM. This cross-sectional study was conducted in western Kenya in 2008 - 2009 to determine the role of NTM in the aetiology of TB-like disease, and demonstrate the confusion they present in the treatment of TB.

Methods: The sputa from 128 smear positive patients were cultured and growth was identified using the Hain’s GenoType^® Mycobacterium CM and GenoType^® Mycobacterium AS kits. The M. tuberculosis complex isolates underwent anti-TB drug susceptibility testing to determine their susceptibility to rifampicin and isoniazid.

Results: No case of multi-drug resistant tuberculosis was isolated. The NTM constituted 7.5% of the isolates.

Conclusion and recommendations: Tuberculosis classically defined on the basis of ZN-smear positive of sputum may be over-diagnosed in western Kenya because some of the infections are caused by NTM. Conventional anti-TB drugs are ineffective against many of the NTM which may be confused with anti-TB multidrug resistance

Keywords: Non-tuberculous mycobacteria; anti-TB drug resistance