Molecular epidemiology and drug resistance of widespread genotypes of Mycobacterium tuberculosis in northwestern Russia.

SETTING: Four administrative territories (Archangel Oblast, Murmansk Oblast, Republic of Karelia, Republic of Komi) in the northwestern federal region of Russia.
OBJECTIVE: To describe the genetic diversity and level of drug resistance in Mycobacterium tuberculosis isolates from new cases of pulmonary tuberculosis.
DESIGN: A total of 176 isolates of M. tuberculosis were tested for drug susceptibility and typed with insertion sequence (IS) 6110 restriction fragment length polymorphism (RFLP) and spoligotyping.
RESULTS: The Beijing family was found to be the most prevalent (47.1%), most frequently clustered and significantly associated with drug resistance to all first-line anti-tuberculosis drugs (isoniazid, rifampicin, ethambutol, streptomycin and pyrazinamide) and ethionamide, when compared to the T and Haarlem families of M. tuberculosis, which were also prevalent in the study population. Some RFLP clusters (4/10) included isolates that originated from patients residing in different territories, and cases infected with multiple strains of M. tuberculosis were apparently present in the collection.
CONCLUSION: The M. tuberculosis population in northwestern Russia appears to be genetically diverse and geographically widespread. Although dominated by isolates assigned to the Beijing family, other families also contribute to the current epidemic, and multiple strain infections may represent a problem in many cases. Extended genetic studies should be encouraged.