Magnitude and Geographical Distribution of Nontuberculous Mycobacteria among People Presumed to Have Pulmonary Tuberculosis in Kenya

Abstract

Background: Globally, awareness of nontuberculous mycobacteria as causative agents of pulmonary disease is on the rise. In Kenya however, there is very limited information on the burden of nontuberculous mycobacteria, as diagnosis of pulmonary infections is usually by sputum smear microscopy which does not distinguish between Mycobacterium tuberculosis complex and nontuberculous mycobacteria, which are both causative agents. This study sought to determine the magnitude, drug susceptibility patterns and geographical distribution of nontuberculous mycobacteria among presumptive tuberculosis patients in selected health facilities including Malindi, Kitale, Busia, Wajir, Nyahururu, Kisii, Machakos and Lamu.

Materials and Methods: This was a laboratory-based cross-sectional study in which 124 Ziehl-Neelsen positive isolates from a previous study were further analyzed. The archived isolates were sub-cultured in Mycobacterium growth indicator tube (MGITTM; BD Sparks, USA) medium and identification was done using GenoType® Mycobacterium assays (HAIN Lifescience, Nehren, Germany). Drug susceptibility against rifampicin, isoniazid and ethambutol was determined by the resistance ratio method and Pearson's Chi-square was used to establish the geographical distribution of species.

Results: The proportion of isolates with nontuberculous mycobacteria was 19.3% and Mycobacterium intracellulare was predominant (41.7%). All 24 identified nontuberculous mycobacterium species were resistant to rifampicin, isoniazid and ethambutol. Wajir had the highest number of infections (CI95% 2.46-54.27, p=0.002).

Conclusion: There was a high magnitude of nontuberculous mycobacteria among presumptive tuberculosis patients. Inappropriate diagnosis of pulmonary infections caused by nontuberculous mycobacteria may lead to patient mismanagement with routinely prescribed anti-tuberculous drugs.