Verification of Etest for penicillin and ceftriaxone susceptibility testing in Streptococcus pneumoniae
Main Article Content
Abstract
Reliable determination of minimum inhibitory concentrations (MICs) is critical for antimicrobial susceptibility testing and clinical decision making. In this study, we evaluated the performance of Etest for penicillin and ceftriaxone using 50 clinical isolates of Streptococcus pneumoniae. Essential agreement (EA), categorical agreement (CA), very major error (VME), major error (ME), and minor error (mE) were calculated based on CLSI M52 breakpoints. For penicillin Etest, EA and CA were 96.0% and 74.0%, respectively, while VME, ME and mE rates were 2.0%, 0.0%, and 26.0%. For ceftriaxone Etest, EA and CA were 94.0% and 62.0%, respectively, while VME, ME and mE rates were 4.0%, 0.0%, and 38.0%. Despite high EA values, CA and mE results were suboptimal because most MIC values of S. pneumoniae clustered around the clinical breakpoints. Therefore, expansion of the isolate collection is necessary to obtain a more accurate evaluation of Etest performance.
Article Details
Keywords
Streptococcus pneumoniae, Etest penicillin, Etest ceftriaxone
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