Characterization of drug-resistant isolates of Mycobacterium tuberculosis derived from Russian inmates.

SETTING

Tuberculosis ward of a prison in Russia.

OBJECTIVE

Molecular characterization of drug-resistant isolates.

DESIGN

Isolates were collected from all tuberculosis patients occurring in the prison over a 1-year period.

RESULTS

Of 130 patients studied, 17 patients produced pan-susceptible isolates and 113 produced isolates resistant to at least one drug, including 85 multidrug-resistant isolates. Mutations at katG315 occurred in 98% of isoniazid-resistant isolates. Mutations in rpoB were found in 89% of rifampicin-resistant isolates. Mutations in pncA occurred in 13% of the 75 isolates tested. By spoligotyping, members of the Beijing (55 isolates) and LAM (31 isolates) families were identified. By IS6110 genotyping, two groups (34 and 55 isolates) of related isolates were found, including three clusters (10, 12, and 16 isolates) with identical patterns. In a study of samples collected 3 months apart from 28 patients, four patients produced isolates containing a mixture of strains and five patients produced specimens containing distinctly different isolates. Isolates of nine patients acquired additional drug resistance.

CONCLUSION

Three families of strains accounted for much of the drug-resistant tuberculosis in this population. Multiple resistance, acquisition of resistance, and infection with two or more strains as well as reinfection were observed.