Pyrazinamide resistance in MDR and extensively drug-resistant tuberculosis.

Background: Pyrazinamide (PZA) is an important first-line antituberculosis drug in drug resistant and drug sensitive regimen. Incorporation of pyrazinamide into the first-line regimen had made it possible to reduce the treatment duration to six months. But drug resistant rate of PZA is high in MDR and XDR tuberculosis. Methods: We reviewed a phase II clinical trial in our hospital to identify the clinical characteristics of PZA resistant tuberculosis. Results: In our study, the mean time of anti-tuberculosis treatment before enrolled in the study was 2.6 +/- 3.1 years in the PZA resistant (PZAr) group and 2.3 +/- 1.4 years in the PZA sensitive (PZAs) group. The mean time of using PZA prior to the study in PZAr group and PZAs group were 1.1 +/- 2.0 years and 0.5 +/- 0.3 years respectively. The rate of PZA resistance was 80% (16/20) in MDR-TB and 100% (7/7) in XDR-TB. Conclusions: So whether to use PZA in MDR or XDR tuberculosis regimen still needs be identified.