Graduate School, Khon Kaen University, Khon Kaen 40002, Thailand.
J Antimicrob Chemother. 2012 Nov;67(11):2626-30. doi: 10.1093/jac/dks267. Epub 2012 Jul 13.
To detect carbapenemases in clinical isolates of Enterobacteriaceae collected from patients in a university hospital in Thailand between October 2010 and August 2011.
A total of 4818 Enterobacteriaceae isolates were screened for the presence of carbapenemases by ertapenem and imipenem disc diffusion tests. All positive screening isolates were subjected to modified Hodge test, phenylboronic acid- and EDTA-carbapenem combined disc tests and two multiplex PCRs of bla(IMP), bla(VIM), bla(SPM), bla(SIM) and bla(GIM), and of bla(KPC), bla(NDM) and bla(OXA-48). Carbapenemase-producing isolates were typed by PFGE and then characterized by antimicrobial susceptibility tests. Conjugation was performed using a broth culture mating method.
Two isolates each of Escherichia coli, Klebsiella pneumoniae and Citrobacter freundii produced NDM-1, whereas two other isolates of K. pneumoniae produced IMP-14a. DNA fingerprints revealed that the metallo-β-lactamase (MBL)-producing isolates were of different strains except for clonal strains of C. freundii. In vitro transfer of carbapenem resistance was successful for the eight MBL-producing isolates. All MBL producers were susceptible to colistin and tigecycline. The six NDM-producing isolates were recovered from the urine of three patients, who had no history of travel outside Thailand. Interestingly, one patient had chronic urinary tract infections caused by a K. pneumoniae strain and two strains of E. coli producing NDM-1.
Surveillance of carbapenemases, particularly NDM-1, in Enterobacteriaceae is urgently needed to control and prevent the spread of these resistance determinants in our country.
检测 2010 年 10 月至 2011 年 8 月期间泰国一所大学医院患者分离的肠杆菌科临床分离株中产碳青霉烯酶的情况。
通过 ertapenem 和亚胺培南纸片扩散试验筛选 4818 株肠杆菌科分离株中是否存在碳青霉烯酶。对所有阳性筛选分离株进行改良 Hodge 试验、苯硼酸和 EDTA 碳青霉烯复合纸片试验以及 bla(IMP)、bla(VIM)、bla(SPM)、bla(SIM)和 bla(GIM)以及 bla(KPC)、bla(NDM)和 bla(OXA-48)的两种多重 PCR。产碳青霉烯酶的分离株通过 PFGE 进行分型，然后通过药敏试验进行特征分析。通过肉汤培养交配法进行接合。
每株大肠埃希菌、肺炎克雷伯菌和弗氏柠檬酸杆菌各有 2 株产生 NDM-1，而另 2 株肺炎克雷伯菌则产生 IMP-14a。DNA 指纹图谱显示，除弗氏柠檬酸杆菌的克隆株外，产金属β-内酰胺酶（MBL）的分离株为不同株。对 8 株 MBL 产生菌的体外耐药性转移是成功的。所有 MBL 产生菌均对多粘菌素和替加环素敏感。6 株产 NDM 的分离株从 3 名患者的尿液中分离出来，这 3 名患者均无泰国境外旅行史。有趣的是，一名患者患有慢性尿路感染，由一株肺炎克雷伯菌和两株产 NDM-1 的大肠埃希菌引起。
迫切需要对肠杆菌科中的碳青霉烯酶，特别是 NDM-1 进行监测，以控制和预防这些耐药决定因素在我国的传播。
