Revisiting problems and solutions to decrease Mycobacterium tuberculosis pyrazinamide false resistance when using the Bactec MGIT 960 system

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Abstract

Pyrazinamide (PZA) is a first-line key drug used in combination with other agents for the treatment of tuberculosis (TB). Phenotypic and molecular assays for testing susceptibility of Mycobacterium tuberculosis (Mtb) to PZA have been developed, with the assay in liquid medium at acidic pH in the Bactec MGIT 960 (M960) system being routinely used in the mycobacteriology laboratories. However, false resistance to PZA by this method was reported to occur by several investigators, mostly due to high Mtb inoculum, which may impair drug activity by increasing the pH of the medium. In this study, a revision of the literature on the issue of false resistance in the M960 PZA assay was performed. In the reports examined, all improvements of the M960 test proposed to decrease false resistant results were based on the use of reduced inoculum densities of Mtb cells, to be easily translated into laboratory practice.

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Authors

Alessandro Mustazzolu - Istituto Superiore di Sanità, Scientific Communication Service, Rome

Claudio Piersimoni - Regional Reference Mycobacteria Laboratory, United Hospitals, Ancona

Angelo Iacobino - Istituto Superiore di Sanità, Department of Infectious Diseases, Rome

Federico Giannoni - Istituto Superiore di Sanità, Department of Infectious Diseases, Rome

Barbara Chirullo - Istituto Superiore di Sanità, Department of Food Safety and Veterinary Public Health, Rome

Lanfranco Fattorini - Istituto Superiore di Sanità, Department of Infectious Diseases, Rome

How to Cite
Mustazzolu, A., Piersimoni, C., Iacobino, A., Giannoni, F., Chirullo, B., & Fattorini, L. (2019). Revisiting problems and solutions to decrease Mycobacterium tuberculosis pyrazinamide false resistance when using the Bactec MGIT 960 system. Annali dell’Istituto Superiore Di Sanità, 55(1), 51-54. Retrieved from https://annali.iss.it/index.php/anna/article/view/792
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