Resistance Patterns of Mycobacterium tuberculosis to First-Line Anti-TB Drugs in Kaduna State, North-Western Nigeria

Abstract

The problem of tuberculosis (TB) in Nigeria has been made worse by the issues of drug-resistant Mycobacterium tuberculosis. Resistance associated with treatment failures has become a common occurrence worldwide. Of particular concern is the increasing prevalence of multi-drug resistant M. tuberculosis; organisms resistant to isoniazid and rifampicin, the two drugs that form the backbone of modern short-course therapy. Susceptibility of forty (40) M. tuberculosis isolates to isoniazid (INH), rifampicin (RIF), streptomycin (SM), and ethambutol (EMB) was determined by the proportion method on Lowenstein Jensen egg-based slopes containing critical concentrations of INH, RIF, SM, and EMB (0.2 μg/ml, 40 μg/ml, 4.0 μg/ml, and 2.0 μg/ml respectively). Overall drug resistance was found in 21 (52.5%) isolates. Mono-drug resistance was seen in 9 (22.5%) of the isolates tested and was against streptomycin. Two (5.0%) isolates were found to be MDR. Five (12.5%) were poly-drug resistant. One isolate showed poly-drug resistance to SM and INH, 2 (5%) were poly-drug resistant to SM and EMB, 1 (2.5%) was resistant to INH and EMB. Poly-resistance to SM, INH, and EMB was found in only 1 isolate. No poly-resistance to RIF and EMB, RIF and SM, or RIF/SM/EMB was observed.