3种方法评估肺炎克雷伯菌及鲍曼不动杆菌对替加环素的体外药敏结果分析

Effect of Tigecycline on Klebsiella pneumoniae and Acinetobacter baumanaii by susecptibility testing in vitro

目的:比较3种药敏方法在判定菌株对替加环素不敏感结果的一致性。方法:收集Vitek 2 Compact系统测定的对替加环素不敏感菌株110株,其中肺炎克雷伯菌59株,鲍曼不动杆菌51株。纸片扩散法及MIC Test Strip(MTS)法进行复核检测对替加环素的敏感性。结果:以MTS法为参考方法,Vitek 2法检测菌株与MTS法的一致率,MTS法采用EUCAST折点优于FDA折点,并且误差率较FDA折点低。Vitek2法检测肺炎克雷伯菌对替加环素敏感性与MTS法的一致率高于纸片法,而检测鲍曼不动杆菌的一致率低于纸片法。产ESBL肺炎克雷伯菌对替加环素的耐药率高于非产ESBL肺炎克雷伯菌,Vitek 2 MIC50较MTS MIC50高一个稀释度。CRAB对替加环素的敏感率为100%(MTS法/FDA折点),CSAB的中介率为77.8%,未发现耐药株。结论:Vitek 2法与纸片法均不能作为检测肺炎克雷伯菌与鲍曼不动杆菌对替加环素敏感性的常规方法,应采用MTS法或肉汤稀释法对不敏感菌株进行复核。

Objective： To compare Klebsiella pneumoniae and Acinetobacter baumanaii in vitro susceptibility to tigecycline by three different susceptibility testing methods. Methods： Fifty nine isolates of Klebsiella pneumoniae and 51 isolates of Acinetobacter baumanaii, nonsusceptibility to tigecycline by Vitek 2 were collected from February 2014 to January 2015, and then were confirmed by disk diffusion method and MIC Test Strip （MTS）. Results：Compared with MTS method which was on the basis of EUCAST interpretive criteria, the CA of Vitek 2 was higher than FDA for Klebsiella pneumoniae and Acinetobacter baumanaii, and the error was lower. Vitek 2 produced higher CA result for Klebsiella pneumoniae than disk diffusion, but the CA result for Acinetobacter baumanaii was the opposite. The resistance rate of ESBL-producing K. pneumoniae isolates was higher than non-ESBL-producing K. pneumoniae, and Vitek 2 result in MIC50 in 1 dilution was higher compared with MTS. Remarkably high tigecycline susceptibility rates （100%） were found among the Carbapenem-resistant A. baumanaii by MTS method, the intermediate rate of Carbapenem-susceptible A. baumanaii to tigecycline was 77.8%, and no resistant strain to tigecycline was found. Conclusion：For routine susceptibility testing of K. pneumoniae and A. baumannii on tigecycline, the disk method and Vitek2 may not be proper because of the poor correlation of results between the MTS .