title: Testing of susceptibility of Mycobacterium tuberculosis to pyrazinamide with the nonradiometric BACTEC MGIT 960 system.
abstract: The reliability of the novel BACTEC MGIT 960 pyrazinamide (PZA) kit (Becton Dickinson Microbiology Systems, Sparks, Md.) was assessed for testing of susceptibility of Mycobacterium tuberculosis to PZA. Results generated by the BACTEC MGIT 960 system (Becton Dickinson) were compared with those obtained with the BACTEC 460TB system. Extensive proficiency testing (phase I) and reproducibility testing (phase II) as well as susceptibility testing of blinded strains of M. tuberculosis from the Centers for Disease Control and Prevention (phase III) were performed prior to testing 58 strains isolated from clinical specimens (phase IV). After resolution of discrepant results obtained by the two BACTEC methods by two other laboratories which acted as independent arbiters (phase V), overall agreement of the BACTEC MGIT 960 system with the BACTEC 460TB system for PZA testing of phase IV strains was 96.6%. Between the two systems there was no statistically significant difference in time until results were obtained, i.e., 6.8 days (BACTEC MGIT 960) versus 5.4 days (BACTEC 460TB), the latter not counting the time required for a subculture with a growth index of 200, however. The new BACTEC MGIT PZA susceptibility testing procedure works equally well for inocula prepared from liquid (MGIT) and solid (Löwenstein-Jensen) cultures. PZA MGIT medium in plastic tubes yielded results equivalent to medium dispensed in glass tubes.
authors: Swiss National Center for Mycobacteria, Department of Medical Microbiology, University of Zurich, Gloriastrasse 30, 8028 Zurich, Switzerland. plyffer@immv.unizh.ch
authors: Gaby E
authors: GE
authors: Pfyffer
authors: Frantiska
authors: F
authors: Palicova
authors: Sabine
authors: S
authors: Rüsch-Gerdes
mesh_terms: D000995:Antitubercular Agents / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests / Q000379:methods; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics; D011718:Pyrazinamide / Q000494:pharmacology*; D015203:Reproducibility of Results
chemical_list: D000995:Antitubercular Agents; D011718:Pyrazinamide