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Title: Multicentre testing of the EUCAST broth microdilution reference method for MIC determination on mycobacterium tuberculosis
Author: Schön, Thomas
Werngren, Jim
Machado, Diana
Borroni, Emanuele
Wijkander, Maria
Lina, Gerard
Mouton, Johan
Matuschek, Erika
Kahlmeter, Gunnar
Giske, Christian
Santín Cerezales, Miguel
Cirillo, Daniela Maria
Viveiros, Miguel
Cambau, Emmanuelle
Keywords: Isoniazida
Issue Date: 1-Feb-2021
Publisher: European Society of Clinical Microbiology and Infectious Diseases
Abstract: Objectives: the first objective of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) subcommittee for antimycobacterial susceptibility testing (AMST), launched in 2016, was to set a reference method for determining the MICs of antituberculous agents, since many protocols are used worldwide and a consensus one is needed for the determination of microbiological breakpoints. Methods: during 2017 and 2018, MIC determination protocols were evaluated prospectively in a multicentre study within the four AMST laboratories. MIC results were obtained for isoniazid, levofloxacin and amikacin on the reference strain Mycobacterium tuberculosis H37Rv ATCC 27294. Broth microdilution (BMD) in Middlebrook 7H9 and solid medium dilution (SMD) in Middlebrook 7H10 were performed using two inoculum concentrations. MICs were interpreted with regard to visual and 99% inhibition after 7, 14 or 21 days of incubation for BMD and 21 days for SMD. Results: following the EUCAST reference protocol, intra- and inter-assay agreements were within ±1 MIC dilution for >95% of the observations for the three drugs in both methods. MIC values, presented as MIC mode (range) for BMD and SMD respectively, were: 0.03 (0.015-0.06) mg/L and 0.12 (0.06-0.25) mg/L for isoniazid, 0.25 mg/L (0.25-0.5) and 0.5 mg/L (0.12-0.5) for levofloxacin, and 0.5 mg/L (0.5-1.0) and 0.5 mg/L (0.5-1.0) for amikacin. Conclusions: both SMD and BMD were reproducible and eligible as a reference method for MIC determination of the Mycobacterium tuberculosis complex (MTBC). BMD was finally selected as the EUCAST reference method. From now on it will be used to set epidemiological cut-off values and clinical breakpoints of new and old antituberculous agents.
Note: Reproducció del document publicat a:
It is part of: Clinical Microbiology and Infection, 2021, vol. 27, num. 2, p. 288.e1-288.e4
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ISSN: 1198-743X
Appears in Collections:Articles publicats en revistes (Institut d'lnvestigació Biomèdica de Bellvitge (IDIBELL))
Articles publicats en revistes (Ciències Clíniques)

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