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Alarming new "superbug" gene found in animals and people in China - MCR-1 - Could spread worldwide

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  • Alarming new "superbug" gene found in animals and people in China - MCR-1 - Could spread worldwide

    Wed Nov 18, 2015

    LONDON, | BY KATE KELLAND


    A new gene that makes bacteria highly resistant to a last-resort class of antibiotics has been found in people and pigs in China - including in samples of bacteria with epidemic potential, researchers said on Wednesday.

    The discovery was described as "alarming" by scientists, who called for urgent restrictions on the use of polymyxins - a class of antibiotics that includes the drug colistin and is widely used in livestock farming.

    "All use of polymyxins must be minimized as soon as possible and all unnecessary use stopped," said Laura Piddock, a professor of microbiology at Britain's Birmingham University who was asked to comment on the finding.

    Researchers led by Hua Liu from the South China Agricultural University who published their work in the Lancet Infectious Diseases journal found the gene, called mcr-1, on plasmids - mobile DNA that can be easily copied and transferred between different bacteria.
    This suggests "an alarming potential" for it to spread and diversify between bacterial populations, they said.

    The team already has evidence of the gene being transferred between common bacteria such as E.coli, which causes urinary tract and many other types of infection, and Klesbsiella pneumoniae, which causes pneumonia and other infections.

    This suggests "the progression from extensive drug resistance to pandrug resistance is inevitable," they said.


    "(And) although currently confined to China, mcr-1 is likely to emulate other resistance genes ... and spread worldwide."

    Read More:
    A new gene that makes bacteria highly resistant to a last-resort class of antibiotics has been found in people and pigs in China - including in samples of bacteria with epidemic potential, researchers said on Wednesday.
    ?Addressing chronic disease is an issue of human rights ? that must be our call to arms"
    Richard Horton, Editor-in-Chief The Lancet

    ~~~~ Twitter:@GertvanderHoek ~~~ GertvanderHoek@gmail.com ~~~

  • #2
    Emergence of plasmid-mediated colistin resistance mechanism MCR-1 in animals and human beings in China: a microbiological and molecular biological study


    18 November 2015


    Summary

    Background

    Until now, polymyxin resistance has involved chromosomal mutations but has never been reported via horizontal gene transfer. During a routine surveillance project on antimicrobial resistance in commensal Escherichia coli from food animals in China, a major increase of colistin resistance was observed. When an E coli strain, SHP45, possessing colistin resistance that could be transferred to another strain, was isolated from a pig, we conducted further analysis of possible plasmid-mediated polymyxin resistance. Herein, we report the emergence of the first plasmid-mediated polymyxin resistance mechanism, MCR-1, in Enterobacteriaceae.

    Methods

    The mcr-1 gene in E coli strain SHP45 was identified by whole plasmid sequencing and subcloning. MCR-1 mechanistic studies were done with sequence comparisons, homology modelling, and electrospray ionisation mass spectrometry. The prevalence of mcr-1 was investigated in E coli andKlebsiella pneumoniae strains collected from five provinces between April, 2011, and November, 2014. The ability of MCR-1 to confer polymyxin resistance in vivo was examined in a murine thigh model.

    Findings

    Polymyxin resistance was shown to be singularly due to the plasmid-mediated mcr-1 gene. The plasmid carrying mcr-1 was mobilised to an E coli recipient at a frequency of 10−1 to 10−3 cells per recipient cell by conjugation, and maintained in K pneumoniae and Pseudomonas aeruginosa. In an in-vivo model, production of MCR-1 negated the efficacy of colistin. MCR-1 is a member of the phosphoethanolamine transferase enzyme family, with expression in E coli resulting in the addition of phosphoethanolamine to lipid A. We observed mcr-1 carriage in E coli isolates collected from 78 (15%) of 523 samples of raw meat and 166 (21%) of 804 animals during 2011–14, and 16 (1%) of 1322 samples from inpatients with infection.

    Interpretation

    The emergence of MCR-1 heralds the breach of the last group of antibiotics, polymyxins, by plasmid-mediated resistance. Although currently confined to China, MCR-1 is likely to emulate other global resistance mechanisms such as NDM-1. Our findings emphasise the urgent need for coordinated global action in the fight against pan-drug-resistant Gram-negative bacteria.

    Funding

    Ministry of Science and Technology of China, National Natural Science Foundation of China.
    ?Addressing chronic disease is an issue of human rights ? that must be our call to arms"
    Richard Horton, Editor-in-Chief The Lancet

    ~~~~ Twitter:@GertvanderHoek ~~~ GertvanderHoek@gmail.com ~~~

    Comment


    • #3
      Source: http://www.bbc.com/news/health-34857015

      Antibiotic resistance: World on cusp of 'post-antibiotic era'
      By James Gallagher Health editor, BBC News website
      3 hours ago

      The world is on the cusp of a "post-antibiotic era", scientists have warned after finding bacteria resistant to drugs used when all other treatments have failed.

      They identified bacteria able to shrug off the drug of last resort - colistin - in patients and livestock in China.

      They said that resistance would spread around the world and raised the spectre of untreatable infections...

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