Potential for erroneous results indicating resistance when using the Bactec MGIT 960 system for testing susceptibility of Mycobacterium tuberculosis to pyrazinamide.
During susceptibility testing of 743 isolates of Mycobacterium tuberculosis to pyrazinamide (PZA) using the Bactec 960 system, 57 (7.7%) isolates showed PZA resistance. Repeat testing of resistant isolates with the Bactec 460 reference method confirmed 33 (4.4%) of these isolates as resistant, and 24 (3.2%) were susceptible. Erroneous results for resistance with the Bactec 960 were confirmed by testing the 24 discordant isolates for pyrazinamidase and mutations in the pncA gene.
Chedore
Pamela
P
Public Health Laboratory-Toronto, Ontario Agency for Health Protection and Promotion, 81 Resources Road, Toronto, Ontario M9P 3T1, Canada. Pam.Chedore@oahpp.ca
Bertucci
Lina
L
Wolfe
Joyce
J
Sharma
Meenu
M
Jamieson
Frances
F
D000995:Antitubercular Agents / Q000494:pharmacology*; D003951:Diagnostic Errors; D024881:Drug Resistance, Bacterial; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D011718:Pyrazinamide / Q000494:pharmacology*
D000995:Antitubercular Agents; D011718:Pyrazinamide