[Investigation of pyrazinamide resistance in multidrug-resistant tuberculosis cases in Hospital of Pulmonary Diseases, Izmir, Turkey].

Pyrazinamide (PZA) is one of primary drugs for antituberculous treatment. The aim of this study was to determine the rates of PZA resistance in multidrug-resistant (MDR) and susceptible Mycobacterium tuberculosis (MTB) strains isolated from patients who were admitted to our hospital. MDR strains have been isolated between 2005-2007 years, and susceptible strains were chosen randomly among the collection of the strains of the same period. MTB isolates were grown in BACTEC 960 full automatized broth system (Becton Dickinson, Sparks, MD) and Lowenstein-Jensen solid medium. Identification was done by radiometric BACTEC 460 NAP procedure. Antibiotic susceptibility testing against conventional anti-tuberculous drugs (streptomycin, isoniazide, rifampisin, etambutol) was performed by the radiometric BACTEC 460 system and PZA susceptibility was worked out by BD MGIT 960 PZA Kit (Becton Dickinson, Sparks, MD) with the use of 100.0 microg/ml critical concentrations of PZA. As a result, two of the 65 (3.1%) MTB susceptible strains and 16 of 63 (25.4%) MDR-MTB isolates were found resistant to PZA. In conclusion, due to the high PZA resistance rate in MDR-MTB isolates, susceptibility testing against PZA should be done in MDR-TB cases; however, since PZA resistance rate was low in new susceptible cases, it was thought that testing susceptibility of PZA is not necessary as a routine procedure in our region.