Epidemiological analysis of Mycobacterium tuberculosis strains isolated in Lodz, Poland

BACKGROUND: Mycobacterium tuberculosis is one of the most dangerous human pathogens. Molecular typing of M. tuberculosis has allowed better control of tuberculosis and, among other benefits, identification of genetic lineages among strains. OBJECTIVE: To test the potential of polymerase chain reaction (PCR) based methods for the epidemiological study of M. tuberculosis strains isolated from patients residing in a single city. DESIGN: We performed spoligotyping, mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) typing and insertion sequence (IS) 6110 restriction fragment length polymorphism (RFLP) analyses of 234 clinical strains of M. tuberculosis collected over 2 years from the Polish city of Lodz. RESULTS: Spoligotyping analysis revealed 84 spoligotypes with a shared international type and 50 unique spoligotypes. Subtyping via 15- and 19-loci MIRU-VNTR analyses revealed 154 patterns with 117 unique profiles, and 159 patterns with 126 unique profiles, respectively. Spoligotyping combined with MIRU-VNTR 15- and 19 loci analyses revealed 132 and 146 unique profiles, respectively. Overall, 96 strains clustered via MIRU-VNTR typing were used in IS6110-RFLP analysis. Complete congruence of patterns revealed by PCR-based methods was noted for 40 strains, of which 36 were isolated from epidemiologically linked patients. CONCLUSION: The combination of 15-loci MIRU-VNTR typing with spoligotyping is useful for primary analysis of M. tuberculosis strains; however, additional use of MIRU 23 should be considered. Strains clustered by PCR-based methods should be further analysed by IS6110-RFLP typing.