Daptomycin Etest MICs for methicillin-resistant Staphylococcus aureus vary among different media

Journal of Infection and Chemotherapy : Official Journal of the Japan Society of Chemotherapy
Hanae NakashimaHiroshi Saito

Abstract

For optimum activity of daptomycin (DAP) in vitro, medium supplemented with calcium ions at physiological concentration (i.e., 50 mg/l) is required for determination of DAP minimum inhibitory concentration (MIC) in the Clinical and Laboratory Standards Institute (CLSI) broth microdilution (BMD) method. However, our literature review found that Mueller-Hinton agar (MHA) brands used for the DAP Etest had different calcium ion (Ca²⁺) concentrations among the reports. For 98 clinical methicillin-resistant Staphylococcus aureus isolates previously unexposed to DAP, MICs were assessed by use of the Etest with MHA plates with different media (MHA-A, MHA-B, and MHA-C) and compared with those from the CLSI reference BMD method. The instructions for the Etest recommend MHA with Ca²⁺ of 25-40 mg/l for DAP MIC testing; Ca²⁺ concentrations for each type of MHA were 20.4 mg/l in MHA-A, 45.2 mg/l in MHA-B, and 52.0 mg/l in MHA-C. When the MIC₅₀/MIC₉₀ of the clinical isolates were studied, the Etest MICs for MHA-A were 1-fold dilution higher than for the BMD value. In contrast, for MHA-B they were 1-fold dilution lower, and for MHA-C MIC₅₀ was 1.5-fold dilution lower and MIC₉₀ was 2-fold dilution lower. MICs measured in MHA with higher Ca²⁺ te...Continue Reading

References

Jun 23, 2010·European Journal of Clinical Microbiology & Infectious Diseases : Official Publication of the European Society of Clinical Microbiology·L M Koeth, J M DiFranco

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Citations

Jan 18, 2014·Materials Science & Engineering. C, Materials for Biological Applications·Cunfeng SongLizong Dai
Jul 25, 2014·Diagnostic Microbiology and Infectious Disease·Ayumi YoshizumiKazuhiro Tateda
Jun 29, 2014·European Journal of Clinical Microbiology & Infectious Diseases : Official Publication of the European Society of Clinical Microbiology·E McElvania TeKippeC-A D Burnham
Jan 26, 2018·Journal of Clinical Microbiology·Romney M HumphriesUNKNOWN CLSI Methods Development and Standardization Working Group of the Subcommittee on Antimicrobial Susceptibility Testing
Oct 5, 2013·Clinical Microbiology Reviews·Romney M HumphriesGeorge Sakoulas

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