Department of Clinical Microbiology, Auckland District Health Board, Park Road, Grafton, Auckland, New Zealand.
Int J Antimicrob Agents. 2012 Jun;39(6):529-33. doi: 10.1016/j.ijantimicag.2012.02.017. Epub 2012 Apr 21.
The global spread of New Delhi metallo-β-lactamase (NDM) is of significant public health concern. This study sought to determine whether bla(NDM) was present in Enterobacteriaceae isolates displaying resistance to carbapenems that were submitted to the National Antibiotic Reference Laboratory, Institute of Environmental Science and Research (Porirua, New Zealand) during 2009 and 2010. Isolates were tested for the presence of β-lactamase genes and 16S rRNA methylase genes by polymerase chain reaction (PCR) and sequencing. Plasmid transfer studies were undertaken on isolates found to be harbouring bla(NDM). Molecular typing was performed by multilocus sequence typing (MLST). The bla(NDM-1) gene was identified in four Enterobacteriaceae isolates (two Escherichia coli, one Klebsiella pneumoniae and one Proteus mirabilis) from four patients in New Zealand hospitals in 2009 and 2010. In addition, the bla(NDM-6) gene, which differed from bla(NDM-1) by a point mutation at position 698 (C→T), was also identified in an E. coli isolate from the same patient who harboured the bla(NDM-1)-positive P. mirabilis. All four patients had recently been hospitalised or received health care in India. Four of the isolates also produced a CTX-M-15 extended-spectrum β-lactamase and/or plasmid-mediated AmpC β-lactamase, and all five isolates harboured the plasmid-mediated 16S rRNA methylase rmtC gene. The E. coli types were diverse by MLST, and the K. pneumoniae isolate belonged to the internationally disseminated sequence type 11 (ST11) clone. These findings further illustrate the diversity of phenotypic and genotypic features found in association with bla(NDM), in addition to documenting the international spread of this resistance mechanism, notably into a country with historically low rates of antimicrobial resistance.
新德里金属β-内酰胺酶(NDM)的全球传播引起了人们的极大关注。本研究旨在确定 2009 年至 2010 年期间,新西兰因弗卡吉尔环境科学研究所国家抗生素参考实验室提交的耐碳青霉烯类肠杆菌科分离株中是否存在 bla(NDM)。通过聚合酶链反应(PCR)和测序检测β-内酰胺酶基因和 16S rRNA 甲基化酶基因的存在。对携带 bla(NDM)的分离株进行质粒转移研究。通过多位点序列分型(MLST)进行分子分型。2009 年和 2010 年,新西兰四家医院的四名患者的四种肠杆菌科分离株(两株大肠埃希菌、一株肺炎克雷伯菌和一株奇异变形杆菌)中发现 bla(NDM-1)基因。此外,还在同一患者携带 bla(NDM-1)阳性奇异变形杆菌的大肠埃希菌分离株中发现了 bla(NDM-6)基因,该基因与 bla(NDM-1)在 698 位(C→T)点突变不同。四名患者均有近期在印度住院或接受医疗保健的经历。四个分离株还产生了 CTX-M-15 型超广谱β-内酰胺酶和/或质粒介导的 AmpC β-内酰胺酶,所有五个分离株均携带质粒介导的 16S rRNA 甲基化酶 rmtC 基因。根据 MLST,大肠埃希菌的类型多种多样,肺炎克雷伯菌分离株属于国际传播的 ST11 克隆。这些发现进一步说明了与 bla(NDM)相关的表型和基因型特征的多样性,此外还记录了这种耐药机制的国际传播,特别是进入了一个历史上抗菌药物耐药率较低的国家。