Deshpande Payal, Rodrigues Camilla, Shetty Anjali, Kapadia Farhad, Hedge Ashit, Soman Rajeev
Dept of Research, P.D.Hinduja National Hospital & Medical Research Centre, Mumbai, India.
J Assoc Physicians India. 2010 Mar;58:147-9.
Carbapenems are among the few useful antibiotics against multidrug resistant gram negative bacteria particularly those with extended spectrum beta lactamase. However resistance to carbapenems occurs and is mediated by mechanisms like loss of outer membrane proteins and production of beta lactamase that is capable of hydrolyzing carbapenems. An alert issued in the UK in 2009 warned of an increasing number of carbapenem resistant Enterobacteriaceae strains identified in UK hospital patients. Many of them were recently hospitalized in India and Pakistan and had new type of metallo beta lactamase designated as New Delhi Metallo-1 (NDM-1).
To assess the production of NDM-1 type Metallo beta lactamase enzyme in Enterobacteriaceae at a tertiary care centre in Mumbai.
Consecutive carbapenem resistant Enterobacteriaceae isolates were collected from August 2009 to November 2009. Susceptibility testing for carbapenems was performed by the disc diffusion method. Carbapenemase production was confirmed by Modified Hodge test. These strains were then subjected to single target PCR. A 475bp product was amplified by the NDM primers and visualized on 3% agarose gel.
Modified Hodge test was positive for all carbapenem resistant isolates. Of 24 carbapenem resistant Enterobacteriaceae 22 were NDM producers while 2 were NDM non producers. Amongst the 22 NDM producing organisms 10 were Klebsiella spp, 9 were Escherichia coli, 2 were Enterobacter spp and 1 was Morganella morganii. This high number in a relatively short span is a worrisome trend that compromises the treatment options with the carbapenems.
碳青霉烯类抗生素是为数不多的对多重耐药革兰氏阴性菌有效的抗生素，尤其是对那些产超广谱β-内酰胺酶的细菌。然而，对碳青霉烯类抗生素的耐药性确实存在，其介导机制包括外膜蛋白的缺失以及能够水解碳青霉烯类抗生素的β-内酰胺酶的产生。2009年英国发布的一项警报警告称，在英国医院患者中发现的耐碳青霉烯类肠杆菌科菌株数量不断增加。其中许多患者近期曾在印度和巴基斯坦住院，且携带一种新型金属β-内酰胺酶，命名为新德里金属β-内酰胺酶-1（NDM-1）。
评估孟买一家三级医疗中心的肠杆菌科细菌中NDM-1型金属β-内酰胺酶的产生情况。
收集2009年8月至2009年11月连续分离得到的耐碳青霉烯类肠杆菌科菌株。采用纸片扩散法进行碳青霉烯类抗生素的药敏试验。通过改良Hodge试验确认碳青霉烯酶的产生。然后对这些菌株进行单靶点PCR。用NDM引物扩增出一条475bp的产物，并在3%琼脂糖凝胶上进行可视化分析。
所有耐碳青霉烯类分离株的改良Hodge试验均为阳性。在24株耐碳青霉烯类肠杆菌科细菌中，22株产NDM，2株不产NDM。在22株产NDM的菌株中，10株为克雷伯菌属，9株为大肠埃希菌，2株为肠杆菌属，1株为摩根摩根菌。在相对较短的时间内出现如此高的比例是一个令人担忧的趋势，这会影响碳青霉烯类抗生素的治疗选择。
