Follow us on twitter: @csjmagazine
NEWS Concerns raised over multi-drug resistant bacteria
The mcr-1 gene – a gene that makes bacteria resistant to colistin, an antibiotic of last resort, and that is transferrable between bacteria – has been found in a wide variety of strains of Escherichia coli in China following widespread use of colistin in agriculture. As China prepares to introduce the drug for the first time in human medicine, two new studies published in The Lancet Infectious Diseases provide evidence of how widely the mcr-1 gene has spread to bacteria in clinical settings, including to a minority already resistant to the carbapenem class of antibiotics, and highlights the need for caution and careful prescribing when the country introduces colistin.
Infections that are resistant to carbapenems are already common in many countries and in these cases only a small number of antibiotics are effective, including colistin. In 2015, the mcr-1 gene was discovered in China and subsequently identified in other countries including Denmark, Germany, Vietnam, Spain, and the US, raising fears that bacteria may acquire combined colistin and carbapenem resistance, making them multi-drug resistant. The first study, led by Professor Timothy
Walsh at Cardiff University (UK) and Professor Jianzhong Shen at the China Agricultural University, looked at the prevalence of bacteria carrying the mcr-1 resistance gene in human infections in two hospitals in Zheijang and Guangdong provinces across eight years. Among more than 17000 bacterial isolates associated with infection, mcr-1 was detected in 76/5332 samples of
E.coli and 13/348 samples of Klebsiella pneumoniae. The study is the first to look at risk factors for clinical mcr-1 infection and found that people who had used antibiotics (particularly carbapenems)
before hospitalisation were more likely to carry bacteria with the mcr-1 resistance gene. Among 146 isolates of mcr-1-positive
E.coli identified, only five were also carbapenem resistant. “The emergence of mcr-1 heralds the breach of the last group of antibiotics, such as colistin. The withdrawal of the drug from agricultural use, and its introduction in the clinic might reduce colistin resistance rates in the community, and increase resistance in hospitals where they may be harder to treat or spread more easily. Our study finds that there are significant risk factors for the spread of mcr-1 infections, beyond just rural living and diet. The spread of colistin resistant bacteria will likely worsen when the drug is introduced in humans,” said Professor Tim Walsh. The second study, led by researchers at Zhejiang University (China), tested samples from over 2000 bloodstream infections at 28 hospitals in China. Of the 1495
E.coli samples, 20 were mcr-1 positive, one of which was also carbapenem resistant. Patients with mcr-1- positive infections were all treated successfully with other antibiotics. “The most troubling problem for clinicians
would be the transfer of colistin resistance to a bacterium which is already carbapenem resistant, making it multi-drug resistant. This does not appear to have happened to any great extent in clinical isolates, but the situation should be monitored carefully as the country prepares to introduce colistin for use in humans,” said Professor Yunsong Yu, Zhejiang University
Discussing the findings from both papers in a linked comment, Professor David Paterson, University of Queensland (Australia) and Associate Professor David van Duin, University of North Carolina (US), said: “At this stage we can conclude that the doomsday scenario of convergence of carbapenem resistance and colistin resistance (via mcr-1) has not yet occurred to any great extent in China. However, prior use of carbapenems was a risk factor for mcr-1 producing
E.coli, perhaps implying that the intersection between carbapenem resistance and the presence of this colistin resistance mechanism may yet be seen in the future. Furthermore, the spread of mcr-1 into globally widespread and virulent strains of
E.coli such as ST-131 is cause for ongoing concern and surveillance.”
MARCH 2017
WWW.CLINICALSERVICESJOURNAL.COM I
11
© borzywoj - Fotolia.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72
