摘要
目的建立同时检测肠杆菌科细菌超广谱β内酰胺酶(ESBLs)和 AmpC β内酰胺酶(AmpCs)的头孢噻肟平板试验(CTX-AM)方法。方法将已水化的空白、克拉维酸(CLV 10μg)、氯唑西林(CLX 300μg)和 CLV/CLX(10/300μg)纸片间隔一定距离贴于已接种大肠埃希菌 ATCC25922的头孢噻肟(CTX,0.5μg/ml)-MH 平板和头孢他啶(CAZ,1μg/ml)-MH 平板上,并将待检菌数个菌落涂于各纸片中央,35℃过夜培养,根据各纸片周围细菌生长情况判定β内酰胺酶的类型。以肺炎克雷伯菌 ATCC 700603、阴沟肠杆菌029M 和大肠埃希菌 ATCC 25922作质控,并与双纸片增效试验(DDET)和酶粗提物三维试验(TDEM)进行方法学比对。结果 CTX-AM 试验对58株肠杆菌科细菌进行检测,检出产 AmpCs 的菌株与 TDEM 试验完全一致;CTX-AM 试验检出同时产 ESBLs 和AmpCs 的5株菌中,DDET 2株 ESBLs 阴性;且 CTX-AM 识别的1株产耐酶抑制剂β内酰胺酶的菌株和3株产其他β内酰胺酶的菌株,DDET 试验未能识别。结论 CTX-AM 试验操作简便、结果易于判读、成本低廉,在一块平板上即可完成对 ESBLs 和 AmpCs 的检测,适于各级临床微生物实验室常规应用。
Objective To develop an easy, rapid and reproducible cefotaxime-agar medium（CTX- AM） for phenotypic detection of extended-spectrum β-lactamases （ESBLs） and AmpC β-lactamases （AmpCs） in Enterobacteriaceae. Methods The surface of a cefotaxime （CTX, 0. 5 μg/ml） -Mueller- Hinton agar and ceftizoxime （CAZ, 1μg/ml） -Mueller-Hinton agar plate was inoculated with a lawn of E. coli ATCC 25922 according to the standard disk diffusion method, respectively. Immediately prior to use. blank and clavulanic acid （ 10 μg）, cloxacillin （300 μg） , clavulanic acid/cloxacillin（ 10/300 μg） disk were rehydrated with 10 μl of saline and several colonies of each test organism were applied to disks. Then the results of CTX-AM method to interpret based on a zone of growth around the periphery of disks. A total 58 of ESBL and AmpC producing and non-producing isolates of Enterobacterlaceae, as identified by the double-disk enhancement test （DDET） and the three-dimensional extract method （TDEM）. were used to evaluate the CTX-AM method. Positive control （E. cloacae 029M, K. pneumoniae ATCC 700603 ） and negative control （E. coli ATCC 25922） strains were included. Results The results of CTX-AM method were similar to the DDET and TDEM method for detecting ESBLs and AmpC production in Enterobacteriaceae, respectively. But inhibitor-resistant β-lactamase （IR-BLs） and other β-lactamases were not detected by DDET method. Conclusions The new method described here allows for testing of ESBL and AmpCs on a single plate. It is easy to perform and interpret, and also cost-effective, clinical laboratories may use this technique routinely to detect the presence of ESBL and AmpCs.
出处
《中华检验医学杂志》
CAS
CSCD
北大核心
2007年第8期919-922,共4页
Chinese Journal of Laboratory Medicine
