Resistance of multidrug-resistant strains of Mycobacterium tuberculosis from the Archangel oblast, Russia, to second-line anti-tuberculosis drugs

Multidrug-resistant tuberculosis has become common all over the world, necessitating the inclusion of second-line drugs in treatment regimens. In the present study, the susceptibility of a selection of multidrug-resistant strains of Mycobacterium tuberculosis isolated in the Archangel oblast, Russia, to second-line anti-tuberculosis drugs was analysed. Susceptibility testing of 77 Mycobacterium tuberculosis strains was performed by the Bactec method using the following recommended drug concentrations: capreomycin 1.25 μg/ml; ethionamide 1.25 μg/ml; kanamycin 5 μg/ml; and ofloxacin 2 μg/ml. The majority of strains (92.2%) were resistant to ethionamide. High rates of drug resistance were also found for capreomycin (42.9%) and kanamycin (41.6%), while nearly all strains (98.7%) were susceptible to ofloxacin. The high rates of resistance to ethionamide, capreomycin, and kanamycin show the real burden of drug resistance in the region and pose a serious problem for the treatment of patients with multidrug-resistant tuberculosis.