Evaluation of different tigecycline susceptibility testing methods for Acinetobacter baumannii
10.3760/cma.j.issn.1009-9158.2013.07.008
- VernacularTitle:不同药敏方法检测替加环素对鲍曼不动杆菌敏感性的比较
- Author:
Xiaoxing DU
;
Haiping WANG
;
Ying FU
;
Yan CHEN
;
Yunsong YU
- Publication Type:Journal Article
- Keywords:
Acinetobacter baumannii;
Microbial sensitivity tests;
Tigecycline
- From:
Chinese Journal of Laboratory Medicine
2013;36(7):598-603
- CountryChina
- Language:Chinese
-
Abstract:
Objective To evaluate different tigecycline susceptibility testing methods for A.baumannii.Methods Thirty carbapenem resistant A.baumannii (CRAB) and 30 carbapenem sensitive A.baumannii (CSAB) isolates were randomly collected from 30 hospitals during January to December in 2010 in China retrospectively.MIC and inhibitory zone diameters for tigecyclinc were determined by the susceptibility testing methods such as broth microdilution (BMD),agar dilution,E test,MIC Test Strip (MTS),Vitek2.Data were analyzed by comparing the results from each method to those produced by the reference BMD method.The effects of two different susceptibility test media (M-H and ISO-Sensitest Agar) on the MIC of tigecycline were also analyzed.Results For CSAB isolates,the MIC50/MIC90 of BMD,agar dilution,E test,MTS and Vitek2 were as follows:0.125/0.25 mg/L,0.125/0.25 mg/L,0.5/1 mg/L,0.125/0.25 mg/L and 0.5/0.5 mg/L.Compared with BMD method,the categorical agreement rates (CA) of each method were ≥90％,and produced no very major errors (VME) by Food and Drug Administration (FDA)/ European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints.For CRAB isolates,the MIC50/MIC90 of BMD,agar dilution,E test,MTS and Vitek2 were as follows:2/4 mg/L,4/4 mg/L,4/4 mg/L,1/2 mg/L and 2/4 mg/L.Compared with BMD method,MTS produced 3.3％ (1/30)/6.7％ (2/30) VME(FDA/EUCAST breakpoints),and no method CA was ≥90％.The CA between disk diffusion and BMD results were higher by using the criteria of Jones than FDA breakpoints,but only 66.7％ (20/30) were observed in CRAB isolates,and produced no VME.The MIC of tigecycline determined using M-H agar were usually higher than those using ISO-sensitest Agar.Conclusions Agar dilution,E test,Vitek 2 and disk diffusion appear not to be a suitable method for routine susceptibility testing of tigecycline for CRAB strains.Tigecycline intermediate or resistant results determined by these methods require confirmation by BMD,and MTS results also need to be interpreted with caution.
