Qu Ting-ting, Zhang Jun-li, Wang Jie, Tao Jing, Yu Yun-song, Chen Ya-gang, Zhou Jian-ying, Li Lan-juan
State Key Laboratory for Diagnosis and Treatment of Infectious Disease, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
J Clin Microbiol. 2009 Apr;47(4):1136-42. doi: 10.1128/JCM.01592-08. Epub 2009 Feb 11.
A total of 264 nonduplicate strains of imipenem (IPM)-nonsusceptible Pseudomonas aeruginosa were isolated from hospitals in 16 different regions throughout China. These 264 IPM-nonsusceptible clinical isolates of P. aeruginosa were examined by PCR, a metallo-beta-lactamase (MBL) Etest, a double-disk synergy test (DDST), and a test using combined IPM disks supplemented with various amounts of EDTA. A total of 24 strains positive for MBLs were confirmed by PCR and DNA sequence analysis: 10 strains positive for the bla(VIM-2) gene, 13 strains positive for the bla(IMP-9) gene, and 1 strain positive for the bla(IMP-1) gene. Real-time reverse transcriptase PCR (RT-PCR) was used to verify whether the isolates harboring MBL genes produced the enzyme and was considered the standard for evaluation of the methodology in this study. Of these 24 MBL-positive stains, 21 were confirmed as MBL-producing strains by real time RT-PCR for MBL expression and the other 3 had no expression of MBLs. The sensitivities, specificities, and positive and negative predictive values for the MBL Etest, the DDST, and the combined disk (CD) assay were evaluated. The best method for screening for MBL production in P. aeruginosa strains from China was the CD assay (IMP-EDTA) using 750 microg of EDTA/disk with a breakpoint of >or=6 mm. In the CD assay (IPM-EDTA) with 290 microg and 750 microg EDTA, the zone diameter increases for VIM-2-producing P. aeruginosa isolates were greater than those for IMP-9-producing P. aeruginosa isolates (P = 0.00).
从中国16个不同地区的医院共分离出264株对亚胺培南（IPM）不敏感的铜绿假单胞菌，这些菌株均为非重复菌株。采用聚合酶链反应（PCR）、金属β-内酰胺酶（MBL）Etest、双纸片协同试验（DDST）以及使用添加不同量乙二胺四乙酸（EDTA）的复合IPM纸片进行试验，对这264株临床分离的对IPM不敏感的铜绿假单胞菌进行检测。通过PCR和DNA序列分析共确认了24株产MBL的菌株：10株bla(VIM - 2)基因阳性，13株bla(IMP - 9)基因阳性，1株bla(IMP - 1)基因阳性。采用实时逆转录PCR（RT-PCR）验证携带MBL基因的分离株是否产生该酶，此方法被视为本研究中评估该方法的标准。在这24株MBL阳性菌株中，通过实时RT-PCR检测MBL表达，有21株被确认为产MBL菌株，另外3株无MBL表达。评估了MBL Etest、DDST和复合纸片（CD）试验的敏感性、特异性以及阳性和阴性预测值。在中国铜绿假单胞菌菌株中筛选产MBL的最佳方法是使用含750μg EDTA/纸片且分界值≥6mm的CD试验（IMP-EDTA）。在含有290μg和750μg EDTA的CD试验（IPM-EDTA）中，产VIM-2的铜绿假单胞菌分离株的抑菌圈直径增加幅度大于产IMP-9的铜绿假单胞菌分离株（P = 0.00）。
