Second line drug sensitivity test of multidrug resistant tuberculosis (MDR-TB) isolates using proportional method

Abstract

Drug resistant Tuberculosis (DR-TB) continue to present challenges to the TB control programmes with Multidrug resistant TB (MDR-TB) becoming a major public health threat predisposing individuals to develop Extensively drug resistant TB (XDR-TB), and Totally dug resistant TB (XXDR-TB). The World Health Organization reemphasizes the need for drug Susceptibility testing (DST) for appropriate treatment of individual cases in order to minimize rapid transmission of tuberculosis especially . DR-TB. The study aimed at performing second line drug sensitivity test of MDR-TB isolates to some of the major second line anti-TB drugs. Samples for the study comprised of 22 purposely selected MDR-TB isolates obtained from sputum samples of new AFB smear positive (MDR-TB) patients that were brought to the North West Zonal Tuberculosis Reference Laboratory located at Aminu Kano Teaching Hospital, Kano. The isolates were re-confirmed as MDR-TB using Line prove assay (LPA), and subjected to second line drug sensitivity testing using Proportional methods to some of the second line anti-TB drugs (Ofloxacin, Capreomycin, Ethionamide, & Kanamycin). The results of the study revealed that all the 22 isolates were re-confirmed as MDR-TB using the LPA. The results further shows that all the 22 isolates were sensitive to Ofloxacin (100%) and Capreomycin (100%), followed by Kanamycin (90.9%) and Aminkacin (86.36%) and none of them was identified as XDR-TB. Most of the isolates 16 (72.72%) were however resistant to Ethionamide with only 6 (27.27%) of them being . sensitive. The study revealed absence of XDR-TB among the studied isolates as all of them were sensitive to Ofloxacin and Capreomycin, however majority of them were resistant to Ethionamide and very few to Amikasin and Kanamycin. The study identifies the need for conducting drug susceptibility tests for isolates from patients identified as new AFB smear positive for appropriate treatment so as to reduce transmission of DR-TB.

KEYWORDS: Second Line Drug Sensitivity Test, Proportional Method, MDR-TB