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专业: 医学

[交流] 【转帖】Lancet InfectiousDis.：超级病菌不惧抗生素

抗生素是人类抵御细菌感染类疾病的主要武器。但是，最近，这种武器遭到巨大挑战。8月11日，医学权威杂志《柳叶刀-传染病》（The Lancet Infectious Diseases）刊登的一篇论文警告说，研究者已经发现一种“超级病菌”，它可以让致病细菌变得无比强大，抵御几乎所有抗生素。目前，这种“超级病菌”已经从南亚传入英国，并很可能向全球蔓延。

一种超强的酶

这项研究由英国卡迪夫大学、英国健康保护署和印度马德拉斯大学的医学研究者联合进行。研究人员称，他们在一些赴印度接受过外科手术的病人身上找到一种特殊的细菌，这种细菌含有一种酶，它能存在于大肠杆菌等不同细菌DNA结构的一个线粒体上，并让这些细菌变得威力巨大，对几乎所有的抗生素都具备抵御能力。

去年，卡迪夫大学的研究者蒂莫西·沃尔什首次在一名瑞典病人感染的大肠杆菌和肺炎杆菌中确认了这种酶的存在，并将之命名为NDM-1。

已有致死病例

研究者发现，2009年英国就已经出现了NDM-1感染病例的增加，其中包括一些致死病例。参与这项研究的英国健康保护署专家大卫·利弗莫尔表示，大部分的NDM-1感染都与曾前往印度等南亚国家旅行或接受当地治疗的人有关。

而研究者在英国研究的37个病人中，至少有17人曾在过去1年中前往过印度或巴基斯坦，他们中至少有14人曾在这两个国家接受过治疗，包括肾脏移植手术、骨髓移植手术、透析、生产、烧伤治疗或整容手术等。不过，英国也有10例感染出现在完全没有接受过任何海外治疗的病人身上。

目前的研究发现，携带NDM-1的大肠杆菌感染，会导致许多病人出现尿路感染和血液中毒。一部分感染者病情较为缓和，但也有一些人较为严重。在已发现的NDM-1细菌感染病例中，至少有一例已经对所有已知的抗生素具有抗药性。

英政府发警告

类似的NDM-1感染也出现在了美国、加拿大、澳大利亚和荷兰。尽管目前在英国只发现了约50例病例，但科学家们担心它还会继续蔓延。沃尔什说，现在还无法确定NDM-1在英国到底蔓延到什么程度。英国卫生部已就此发出警告。

“由于频繁的国际航空旅行、全球化以及南亚国家医疗旅游业的兴起，NDM-1现在有机会迅速传播到世界的任何一个角落。”沃尔什警告说。（生物谷Bioon.com）

The Lancet Infectious Diseases doi:10.1016/S1473-3099(10)70143-2

Emergence of a new antibiotic resistance mechanism in India, Pakistan, and the UK: a molecular, biological, and epidemiological study
Karthikeyan K Kumarasamy MPhil a, Mark A Toleman PhD b, Prof Timothy R Walsh PhD b , Jay Bagaria MD c, Fafhana Butt MD d, Ravikumar Balakrishnan MD c, Uma Chaudhary MD e, Michel Doumith PhD c, Christian G Giske MD f, Seema Irfan MD g, Padma Krishnan PhD a, Anil V Kumar MD h, Sunil Maharjan MD c, Shazad Mushtaq MD c, Tabassum Noorie MD c, David L Paterson MD i, Andrew Pearson PhD c, Claire Perry PhD c, Rachel Pike PhD c, Bhargavi Rao MD c, Ujjwayini Ray MD j, Jayanta B Sarma MD k, Madhu Sharma MD e, Elizabeth Sheridan PhD c, Mandayam A Thirunarayan MD l, Jane Turton PhD c, Supriya Upadhyay PhD m, Marina Warner PhD c, William Welfare PhD c, David M Livermore PhD c, Neil Woodford PhD c

Background
Gram-negative Enterobacteriaceae with resistance to carbapenem conferred by New Delhi metallo-β-lactamase 1 (NDM-1) are potentially a major global health problem. We investigated the prevalence of NDM-1, in multidrug-resistant Enterobacteriaceae in India, Pakistan, and the UK.

Methods
Enterobacteriaceae isolates were studied from two major centres in India—Chennai (south India), Haryana (north India)—and those referred to the UK's national reference laboratory. Antibiotic susceptibilities were assessed, and the presence of the carbapenem resistance gene blaNDM-1 was established by PCR. Isolates were typed by pulsed-field gel electrophoresis of XbaI-restricted genomic DNA. Plasmids were analysed by S1 nuclease digestion and PCR typing. Case data for UK patients were reviewed for evidence of travel and recent admission to hospitals in India or Pakistan.

Findings
We identified 44 isolates with NDM-1 in Chennai, 26 in Haryana, 37 in the UK, and 73 in other sites in India and Pakistan. NDM-1 was mostly found among Escherichia coli (36) and Klebsiella pneumoniae (111), which were highly resistant to all antibiotics except to tigecycline and colistin. K pneumoniae isolates from Haryana were clonal but NDM-1 producers from the UK and Chennai were clonally diverse. Most isolates carried the NDM-1 gene on plasmids: those from UK and Chennai were readily transferable whereas those from Haryana were not conjugative. Many of the UK NDM-1 positive patients had travelled to India or Pakistan within the past year, or had links with these countries.

Interpretation
The potential of NDM-1 to be a worldwide public health problem is great, and co-ordinated international surveillance is needed.

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