Evaluation of daptomycin susceptibility testing by Etest and the effect of different batches of media.
One hundred and ninety-five Gram-positive bacteria representing 17 species were tested for susceptibility to daptomycin by broth microdilution and Etest methods. The geometric mean daptomycin MIC was 0.46 mg/L by broth microdilution tests and 0.73 mg/L by Etest. The concentration of calcium in 12 different batches of agar varied from 4 to 36 mg/L. Daptomycin Etest MICs varied inversely with the calcium concentration. Etest daptomycin MICs for quality control strains were within proposed quality control range on media with >20 mg/L of calcium. Monitoring the calcium levels of agar media by testing appropriate quality control strains is important for daptomycin Etests.
Fuchs
P C
PC
The Clinical Microbiology Institute, 9725 SW Commerce Circle, Suite A-1, Wilsonville, OR 97070, USA. cmi@hevanet.com
Barry
A L
AL
Brown
S D
SD
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D003470:Culture Media; D017576:Daptomycin / Q000494:pharmacology*; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000254:growth & development*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods / Q000592:standards; D011786:Quality Control
D000900:Anti-Bacterial Agents; D003470:Culture Media; D017576:Daptomycin; D002118:Calcium