Kim Soo-Young, Hong Seong Geun, Moland Ellen S, Thomson Kenneth S
Center for Research in Anti-Infectives and Biotechnology, Department of Medical Microbiology & Immunology, Creighton University School of Medicine, 2500 California Plaza, Omaha, NE 68178, USA.
J Clin Microbiol. 2007 Sep;45(9):2798-801. doi: 10.1128/JCM.02486-06. Epub 2007 Jun 27.
Although transmissible metallo-beta-lactamases (MBLs) are a serious threat to beta-lactam antibiotic therapy, the CLSI currently does not recommend testing methods for the detection of MBLs. The aim of this study was to evaluate the capability of double-disk tests (DDTs) by using disks containing a combination of the chelators 2-mercaptopropionic acid (MPA) and Tris-EDTA (TE) to detect MBLs. Sixteen isolates (4 Acinetobacter baumannii isolates, 6 Pseudomonas aeruginosa isolates, 1 Serratia marcescens isolate, 1 Aeromonas hydrophila isolate, 1 Aeromonas veronii isolate, 2 Chryseobacterium meningosepticum isolates, and 1 Stenotrophomonas maltophilia isolate) producing IMP-1, IMP-1-like, IMP-18, GIM-1, SPM-1, VIM-2, VIM-2-like, and chromosomal MBLs and 20 isolates (7 Klebsiella pneumoniae isolates, 3 Escherichia coli isolates, 5 Enterobacter cloacae isolates, 2 S. marcescens isolates, 1 Proteus mirabilis isolate, and 2 A. baumannii isolates) producing non-MBL carbapenemases, AmpC beta-lactamases, and extended-spectrum beta-lactamases were tested. The DDT method was evaluated by using four types of chelator disks (TE, high-strength TE, MPA, and TE plus 20 microl of MPA [at various concentrations]) and the beta-lactams imipenem (IPM), meropenem (MEM), ertapenem (ERT), and ceftazidime (CAZ). DDTs with IPM and a TE disk supplemented with 1:320 MPA detected all MBLs and yielded no false-positive results. Some, but not all, MBL producers were detected in IPM-based tests involving the single chelator TE or MPA alone or by ERT- or CAZ-based tests. IPM-based tests with MPA concentrations other than 1:320 and all MEM-based tests had suboptimal sensitivities or specificities. DDT with IPM and a TE disk supplemented with 20 microl of 1:320 MPA appears to be convenient for the detection of MBLs in the clinical laboratory.
尽管可传播的金属β-内酰胺酶（MBLs）对β-内酰胺类抗生素治疗构成严重威胁，但临床和实验室标准协会（CLSI）目前并不推荐用于检测MBLs的检测方法。本研究的目的是评估使用含有螯合剂2-巯基丙酸（MPA）和三羟甲基氨基甲烷-乙二胺四乙酸（TE）组合的纸片进行双纸片试验（DDTs）检测MBLs的能力。对16株产生IMP-1、IMP-1样、IMP-18、GIM-1、SPM-1、VIM-2、VIM-2样和染色体MBLs的菌株（4株鲍曼不动杆菌、6株铜绿假单胞菌、1株黏质沙雷氏菌、1株嗜水气单胞菌、1株维罗纳气单胞菌、2株脑膜败血金黄杆菌和1株嗜麦芽窄食单胞菌）以及20株产生非MBL碳青霉烯酶、AmpCβ-内酰胺酶和超广谱β-内酰胺酶的菌株（7株肺炎克雷伯菌、3株大肠埃希菌、5株阴沟肠杆菌、2株黏质沙雷氏菌、1株奇异变形杆菌和2株鲍曼不动杆菌）进行了检测。通过使用四种类型的螯合剂纸片（TE、高强度TE、MPA以及TE加20微升MPA[不同浓度]）和β-内酰胺类抗生素亚胺培南（IPM）、美罗培南（MEM）、厄他培南（ERT）和头孢他啶（CAZ）对DDT方法进行了评估。使用IPM和补充有1:320 MPA的TE纸片的DDTs检测出了所有MBLs，且未产生假阳性结果。在仅涉及单一螯合剂TE或MPA的基于IPM的试验中，或通过基于ERT或CAZ的试验，检测出了部分但并非全部的MBL产生菌。使用除1:320以外MPA浓度的基于IPM的试验以及所有基于MEM的试验，其敏感性或特异性欠佳。使用IPM和补充有20微升1:320 MPA的TE纸片的DDT似乎便于临床实验室检测MBLs。
