Gene Xpert based detection of drug resistant tuberculosis among retreatment patients visiting National Tuberculosis Centre, Nepal

Abstract

Introduction: Tuberculosis is still one of the major public health problems in Nepal and multi drug resistant and extensively drug resistant tuberculosis (MDR /XDRTB) additionally has become serious issue. Prompt diagnosis and effective treatment of MDR/XDRTB is urgently needed. The main objective of this study was to detect MDR TB using novel molecular techniques (rpob gene mutations) in reference with drug susceptibility test (DST).

Methods: A cross sectional study was carried out identifying MDRTB among retreatment patients using Gene Xpert, culture and DST on first line drugs (FLD-DST). A total of 159 sputum samples were collected from retreatment TB patients (Female 40.3%, Male 59.7%) with median age of 30 years visiting to the DR TB treatment centres of eastern and central Nepal (via private courier and directly to National TB Reference Laboratory (NRL) at NTC from April 2013 to August 2017.

Results: M. tuberculosis and rifampicin resistance were detected on all 159 (100%) samples by Gene Xpert of which, 73.3%, 21.4% and 6.3% were positive, negative and contaminated respectively by culture. FLD-DST was performed on 115 cultures positives of which, 94.78% showed MDRTB, 1.74% showed mono resistance to isoniazid or rifampicin, 0.87% to streptomycin and isoniazid and 3.47% were pan susceptible.

Conclusion: One hundred fifteen of 159 cases detected rifampicin resistances (RR) by Gene Xpert were culture positive and almost 95% strains were MDRTB by FLD-DST, which was found to be higher in 15-60 years group. Sputa from retreatment TB patients required to be tested by rapid diagnostics with reference to culture and DST.