Characterisation of pyrazinamide-resistant Mycobacterium tuberculosis strains isolated in Poland and Germany.

BACKGROUND

Pyrazinamide (PZA) is an important first-line anti-tuberculosis drug that is generally administered with isoniazid, rifampicin, ethambutol and streptomycin.

OBJECTIVE

To analyse the correlation between phenotypic resistance to PZA and genotype to find out whether the great diversity in pncA mutations is epidemiologically useful in tracing the transmission of PZA-resistant Mycobacterium tuberculosis strains among patients.

MATERIALS AND METHODS

The study included 71 PZA-resistant M. tuberculosis strains isolated from 62 Polish and 9 German patients. All strains were analysed using minimal inhibitory concentration value determination, pncA mutation analysis, spoligotyping, 24-loci mycobacterial interspersed repetitive units-variable number of tandem repeats (MIRU-VNTR) and insertion sequence (IS) 6110 restriction fragment length polymorphism (RFLP) fingerprinting.

RESULTS

In 63 isolates, 37 (88.7%) different mutations in the pncA gene were observed, 13 of which had not been previously reported; 11 molecular families with the same MIRU-VNTR and IS6110-RFLP pattern were found. The same mutation was identified in three families, while different ones were identified in the remaining families.

CONCLUSION

Mutations in the pncA gene are a major cause of PZA resistance in M. tuberculosis. pncA mutation analysis can be used to obtain valuable additional information, but should be applied with caution for epidemiological analysis.