自动化药敏系统与K-B纸片扩散法在肠杆菌科细菌中对阿米卡星药敏结果差异的探讨  

Investigation of the susceptibility difference between automation systems and K-B disk diffusion method in Enterobacteriaceae to amikacin

作　　者：牛冬梅[1,2] 周万青[3] 洪骏[2] 陈云[1] 

机构地区：[1]南京医科大学免疫学系,江苏南京210029 [2]南京军区南京总医院全军临床检验医学研究所,江苏南京210002 [3]南京大学医学院附属鼓楼医院检验科,江苏南京210008

出　　处：《东南国防医药》2015年第2期131-134,187,共5页Military Medical Journal of Southeast China

摘　　要：目的探讨自动化微生物药敏系统与K-B纸片扩散法对阿米卡星(AMK)药敏结果的差异。方法收集临床K-B纸片扩散法对AMK敏感、完全耐药及双圈耐药的肠杆菌科细菌分别为4株、4株和13株;其中大肠埃希菌12株,肺炎克雷伯菌8株,产气肠杆菌1株;分别采用Vitek-2 Compact、Phoenix和Micro Scan药敏系统对以上菌株进行AMK的复核,并采用琼脂稀释法测定最低抑菌药物浓度(MIC)值。采用PCR方法检测氨基糖苷类修饰酶基因、整合子及16S rRNA甲基化酶相关基因。结果三种自动化药敏系统对于敏感及完全耐药菌株的药物敏感性结果与K-B纸片扩散法相符;对于在K-B纸片扩散法中呈双圈耐药13株菌,Phoenix和Micro Scan药敏系统结果均为耐药(>32 mg/L);而Vitek 2 Compact药敏卡出现不同结果,其中4株菌株为敏感(≤16 mg/L),4株为中介(32 mg/L),5株为耐药(≥64 mg/L);琼脂稀释法结果显示双圈耐药表型菌株的MIC均>512 mg/L。所测菌株携带不同的氨基糖苷类修饰酶基因及整合子基因盒,主要为aac(6’)-Ⅰ和aad A5-dfr A17;双圈耐药表型菌株均扩增出arm A基因,而敏感菌株和完全耐药菌株均未扩增出该基因。结论在K-B纸片扩散法中出现对AMK呈双圈耐药结果时,自动化鉴定药敏系统中的Vitek系统可能会产生偏差,造成这种差异的出现可能与菌株产arm A基因相关。Objective To investigate the susceptibility difference between automation systems and K-B disk diffusion methods in Enterobacteriaceae to amikacin.Methods The strains which showed sensitive（4 isolates）,resistant（4 isolates） and double zone resistant（13 isolates） to amikacin on clinical K-B disk diffusion method were collected,and including 12 strains of E.coli,8 strains of K.pheumoniae and 1 strain of Enterobacter aerogenes.The susceptibility to amikacin was tested with Vitek-2 Compact,Phoenix and Micro Scan systems respectively,and the MICs to amikacin were detected by agar dilution method.The aminoglycoside modifying genes,integron and 16 S rRNA methylases genes were determined by using PCR and DNA sequence analysis.Results The susceptibility to amikacin was consistent between three kinds of automation systems and K-B disk diffusion method for the sensitive and resistant group strains.The susceptibility results of the 13 strains which showed double zone resistant in disk diffusion method were resistant in Phoenix and Micro Scan systems（〉 32 mg / L）,while different results were shown in Vitek-2 Compact system,including 4 strains of sensitive（≤16 mg / L）,4 strains of intermediary（32 mg / L） and 5 strains of resistant（≥64 mg / L）.The MICs were all above of 512 mg / L for the double zone resistant strains in the agar dilution method.The isolates carried different aminoglycoside modification genes and gene box of integron with the main were aac（6 ＇）-Ⅰand aad A5-dfr A17 respectively.All the strains with double zone resistant to amikacin were positive for arm A and the control strains were negative.Conclusion The Vitek-2 Compact system might not be suitable for the detection of susceptibility of Enterobacteriaceae with the double zone resistant to amikacin in the K-B method.The double zone drug resistance of Enterobacteriaceae to amikacin was correlated with the expression of 16 S rRNA methylase arm A.

关 键 词：阿米卡星 自动化系统 双圈 K-B纸片法 肠杆菌科 

分 类 号：R446.5[医药卫生—诊断学]