Tags

Type your tag names separated by a space and hit enter

Daptomycin Etest MICs for methicillin-resistant Staphylococcus aureus vary among different media.
J Infect Chemother 2012; 18(6):970-2JI

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⁺ tended to be lower. Comparison of MICs between BMD and the Etest for each MHA showed they were significantly different (p < 0.0001). The correlation coefficient was 0.6258 (p < 0.0001) for MHA-A, 0.4224 (p < 0.0001) for MHA-B, and 0.2504 (p = 0.0129) for MHA-C. Our results suggest there are differences in DAP MICs between MIC testing methods and differences between Ca²⁺ concentrations in MHA. For more objective and accurate measurement of DAP MICs, there should be discussion about standardization of Ca²⁺ in MHA.

Authors+Show Affiliations

Department of Clinical Laboratory, Nagano Municipal Hospital, 1333-1 Tomitake, Nagano, Nagano 381-8551, Japan. hanae_nakashima@hospital.nagano.nagano.jpNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

22576751

Citation

Nakashima, Hanae, et al. "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, vol. 18, no. 6, 2012, pp. 970-2.
Nakashima H, Takahashi H, Kameko M, et al. Daptomycin Etest MICs for methicillin-resistant Staphylococcus aureus vary among different media. J Infect Chemother. 2012;18(6):970-2.
Nakashima, H., Takahashi, H., Kameko, M., & Saito, H. (2012). 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, 18(6), pp. 970-2. doi:10.1007/s10156-012-0424-5.
Nakashima H, et al. Daptomycin Etest MICs for Methicillin-resistant Staphylococcus Aureus Vary Among Different Media. J Infect Chemother. 2012;18(6):970-2. PubMed PMID: 22576751.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Daptomycin Etest MICs for methicillin-resistant Staphylococcus aureus vary among different media. AU - Nakashima,Hanae, AU - Takahashi,Hiroshi, AU - Kameko,Mitsuaki, AU - Saito,Hiroshi, Y1 - 2012/05/12/ PY - 2011/11/02/received PY - 2012/04/18/accepted PY - 2012/5/12/entrez PY - 2012/5/12/pubmed PY - 2013/7/24/medline SP - 970 EP - 2 JF - Journal of infection and chemotherapy : official journal of the Japan Society of Chemotherapy JO - J. Infect. Chemother. VL - 18 IS - 6 N2 - 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⁺ tended to be lower. Comparison of MICs between BMD and the Etest for each MHA showed they were significantly different (p < 0.0001). The correlation coefficient was 0.6258 (p < 0.0001) for MHA-A, 0.4224 (p < 0.0001) for MHA-B, and 0.2504 (p = 0.0129) for MHA-C. Our results suggest there are differences in DAP MICs between MIC testing methods and differences between Ca²⁺ concentrations in MHA. For more objective and accurate measurement of DAP MICs, there should be discussion about standardization of Ca²⁺ in MHA. SN - 1437-7780 UR - https://www.unboundmedicine.com/medline/citation/22576751/Daptomycin_Etest_MICs_for_methicillin_resistant_Staphylococcus_aureus_vary_among_different_media_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1341-321X(12)70232-5 DB - PRIME DP - Unbound Medicine ER -