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.