比较Thermo STP6F药敏测定卡与微量肉汤稀释法测定链球菌对抗菌药物的敏感性

Comparative evaluation of Thermo STP6F plate and broth microdilution in antimicrobial susceptibility testing of Streptococcus

目的为临床提供快速、准确、方便的链球菌药敏试验测定方法,比较ThermoSTP6F药敏测定卡与金标准微量肉汤稀释法测定链球菌对抗菌药物的敏感性。方法按CLSI要求,用ThermoSTP6F药敏测定卡检测199株链球菌(肺炎链球菌、化脓链球菌和无乳链球菌),与微量肉汤稀释法结果进行比较。结果两种药敏测试方法涵盖10种抗菌药物对肺炎链球菌的药敏试验结果,分类一致率(CA)为94.6%,基本一致率(EA)为95.5%,重大偏差(VMD)为0.5%,较大偏差(MD)为1.2%,次要偏差(mD)为4.6%;对化脓链球菌两种方法测试结果的CA为99.2%,EA为95.0%,VMD为0.8%,MD为0.8%,mD为0;对无乳链球菌两种方法测试结果的CA为97.8%,EA为93.6%,VMD为1.1%,MD为0.9%,mD为1.2%。ThermoSTP6F药敏测定卡所得数值常比标准方法略高。结论ThermoSTP6F药敏测定卡对链球菌的检测结果与微量肉汤稀释法一致性较好,在用于检测肺炎链球菌对美罗培南敏感性时建议结合E试验法复核确认。

Objective To compare the ability of a rapid test kit,Thermo STP6F plate,and broth microdilution method in testing the antimicrobial susceptibility of Streptococcus isolates for the purpose to provide a rapid,accurate,and convenient method for testing the susceptibility of Streptococcus.Methods A rapid test kit,Thermo STP6F MIC plate,and reference method,broth microdilution,were used to test the susceptibility of 199 strains of Streptococcus (S.pneumoniae,S.pyogenes,and S.agalactiae) according to CLSI recommendations.The results were compared critically.Results For S.pneumoniae,Thermo STP6F plate and manual broth microdilution showed categorical agreement (CA) of 94.6%,essential agreement (EA) of 95.5% in the MIC results of 10 antibiotics.The calculated very major discrepancy (VMD,false susceptible interpretation),major discrepancy (MD, false resistant interpretation),and minor discrepancy (mD,false categorization involving intermediate result) of Thermo STP6F plate per CLSI requirements was 0.5%,1.2%,and 4.6%,respectively,compared to manual broth microdilution.The CA and EA for testing S.pyogenes were 99.2% and 95.0% respectively.Both VMD and MD were 0.8%,mD was 0.In testing S.agalactiae,CA was 97.8%,EA was 93.6%,VMD 1.1%,MD 0.9%,and mD 1.2%. Thermo STP6F plate often reported slightly higher MIC values than the reference method.Conclusions Thermo STP6F plate offers high inter-assay concordance with the reference broth microdilution method.False results should be verified by E-test in clinical practice when testing the susceptibility of S. pneumoniae to meropenem.