Impact of drug-resistant Mycobacterium tuberculosis on treatment outcome of culture-positive cases of tuberculosis in the Archangel oblast, Russia, in 1999.

The objective of this study was to evaluate the outcome of treatment of culture-positive cases of tuberculosis registered in Archangel, Russia, in 1999, and to analyse the influence of Mycobacterium tuberculosis drug resistance on treatment outcome. The outcome of tuberculosis treatment was evaluated for 235 new and 61 previously treated culture-positive cases diagnosed in 1999. Of the 235 new cases, there were 150 (63.8%) cases of treatment completion, 20 (8.5%) cases of treatment failure, 29 (12.3%) cases of death during treatment, and 29 (12.3%) cases in which the patient failed to pick up medications for at least 2 consecutive months. The outcome in 7 (3%) cases was unknown, as the patients were transferred outside the oblast region. Among the 61 previously treated cases, the rate of treatment completion was low (26.2%), and rates of treatment failure (23%) and failure to pick up medications for at least 2 consecutive months (29.5%) were high. The relation between the susceptibility pattern of the infecting strain as determined by the Bactec method and tuberculosis treatment outcome was analysed for 76 patients. The majority (69%) of patients infected with drug-susceptible strains was cured. A large proportion (58.8%) of patients infected with Mycobacterium tuberculosis resistant to more than two drugs did not respond to treatment, i.e. the treatment failed or the patients died. The high rates of death (16.7%) and failure (66.7%) among patients infected with multidrug-resistant strains illustrate the negative impact of multidrug resistance on the outcome of tuberculosis treatment. Pan-resistance was significantly associated with treatment failure (P<0.001). The spread of resistant Mycobacterium tuberculosis has a serious negative impact on the outcome of tuberculosis treatment in Archangel, Russia.