Epidemic of tuberculosis in the former Soviet Union: social and biological reasons.

The tuberculosis epidemic was evidenced in the states of the former Soviet Union at the end of the 20th century. The increase of epidemiological indicators for tuberculosis was accelerated by socio-economic changes in the society. Laboratory analysis also revealed new biological properties of the Mycobacterium tuberculosis isolates in the region, in particular the high level of resistance to antibiotics. Tuberculosis in Russia and the other newly independent states has been caused by M. tuberculosis strains of the W-Beijing family in recent years. These bacteria have rapidly developed resistance to anti-tuberculosis drugs, as a result of prolonged exposure of the patients to inappropriate treatment. The epidemic of drug-resistant tuberculosis caused by the W-Beijing strains represents an important threat to the health of the populations in the newly independent states. It may also adversely affect the global trends in tuberculosis, as there is a clear risk that these drug-resistant strains can spread to other communities outside the former Soviet Union.

Impact of drug resistance on fitness of Mycobacterium tuberculosis strains of the W-Beijing genotype.

Mycobacterium tuberculosis strains of the W-Beijing genotype became a common cause of tuberculosis during the past years and they are often associated with drug resistance. The biological factors facilitating the selection and wide dissemination of these strains are not known. To determine how acquisition of drug resistance affected growth of strains of the W-Beijing genotype, the growth of 55 M. tuberculosis isolates were studied using the BBL MGIT Mycobacteria Growth Indicator Tube and the BACTEC MGIT 960 System. Susceptible strains of non-Beijing genotypes were found to be the most fit strains. Drug-resistant strains of non-Beijing genotypes were more likely to grow slower than susceptible strains (P=0.001). Drug-resistant strains of the W-Beijing genotype had two tendencies of growth: some of them showed reduced growth compared to susceptible strains, while others did not show loss of fitness measured as growth.

Molecular epidemiology and drug resistance of Mycobacterium tuberculosis isolates in the Archangel prison in Russia: predominance of the W-Beijing clone family.

Prisons play a significant role in the epidemiology of drug-resistant tuberculosis. A total of 114 Mycobacterium tuberculosis isolates recovered from patients in the Archangel prison (Archangel, Russia) in 2001 were studied using restriction fragment-length polymorphism analysis and spoligotyping. Drug susceptibility was analyzed by the radiometric broth method (BACTEC; Becton Dickinson Diagnostic Systems). According to genotyping studies, 87 (76.3%) of the isolates belonged to the W-Beijing family. Nearly all (96.6%) W-Beijing isolates were part of a cluster, whereas only 25.9% of the other isolates were clustered (P<.001). The largest cluster comprised 43 patients. Multidrug resistance was high among new (34.0%) and previously treated (55.0%) cases. Resistance to ethambutol (OR, 3.4; 95% CI, 1.0-12.7; P=.03) and streptomycin (OR, 4.2; 95% CI, 1.5-11.6; P=.001) was significantly associated with infection with W-Beijing isolates. Tuberculosis due to drug-resistant W-Beijing isolates is a major problem in the Archangel prison.

Spread of drug-resistant Mycobacterium tuberculosis strains of the Beijing genotype in the Archangel Oblast, Russia.

A collection of 119 strains of Mycobacterium tuberculosis isolated from patients with pulmonary tuberculosis in the Archangel Oblast, Russia, in 1998 and 1999 were studied by using restriction fragment length polymorphism (RFLP) analysis with the IS6110 probe and spoligotyping. Resistance of the strains to antituberculosis drugs was analyzed by the BACTEC method, and mutations associated with rifampin resistance were detected by using the Inno-LiPA Rif. TB test. RFLP analysis and spoligotyping demonstrated that 53 (44.5%) of the strains belonged to the Beijing genotype. These strains showed a significantly higher rate of resistance than M. tuberculosis strains of other genotypes circulating in the region. In particular, 43.4% of the strains of the Beijing genotype were multidrug resistant; in contrast, only 10.6% of the other strains were. Of the strains of the Beijing genotype, 92.5% were part of a cluster, while only 33.3% of the remaining strains were clustered. Analysis of the medical records of the patients demonstrated that individuals infected with a strain of the Beijing genotype were significantly more likely to be alcohol abusers and to have chronic obstructive pulmonary disease prior to the tuberculosis diagnosis. Multivariate analysis showed that both variables were independently associated with infection by strains belonging to the Beijing genotype. Our study demonstrated that strains of the Beijing genotype are an important cause of tuberculosis in the Archangel Oblast and that dissemination of these strains is associated with the high incidence of drug resistance.