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Transferrable colistin resistance found in bacteria from German farm animals

01/2016, 07.01.2016

The BfR draws attention to the transferability of a resistance gene in human and veterinary medicine

Early results from resistance monitoring conducted at the German Federal Institute for Risk Assessment (BfR) show that the transferrable gene mcr-1 which was first detected in China and which causes resistance to the antibiotic colistin is also widespread in intestinal bacteria in farm animals in Germany. Most frequently, this colistin resistance is detected in Escherichia coli of fattening poultry. Transferrable resistance genes can be passed on from harmless intestinal bacteria, so-called commensal bacteria, to pathogens thus making these pathogens harder to treat. It was previously assumed that resistance to colistin could not be transferred between bacteria. The proportion of colistin-resistant bacteria isolates in German farm animals has not increased in recent years. Our results show that this transferrable antimicrobial resistance has been around for many years in Germany, but has only been detected recently. It now needs to be investigated to what extent such transferrable antimicrobial resistance plays a role in the treatment of infectious diseases in humans. "The current results underline that the strategy of a responsible use of antibiotics must be consistently pursued in future", says Professor Dr. Dr. Andreas Hensel, President of the BfR. "As part of a one-health approach, this strategy should encompass all active ingredient groups in veterinary and human medicine." Further biomolecular investigations on the genetic background and transfer potential are now being conducted in order to evaluate possible risks for consumers.

The BfR has tested bacteria isolates from investigations conducted between 2012 and 2015 that were resistant to colistin for the presence of the transferrable gene mcr-1, using a method made available by the European Reference Laboratory in Copenhagen. As part of the resistance monitoring programme, resistance to colistin has been tested in Germany for years. Accordingly, it is known that resistance to colistin is particularly common in isolates of the intestinal bacteria Escherichia coli and in salmonella from poultry populations. The BfR is now testing further isolates from the years prior to 2012.

An article published in the medical magazine The Lancet Infectious Diseases (DOI: http://dx.doi.org/10.1016/S1473-3099(15)00424-7) described the detection of the transferrable mcr-1 gene in China which confers resistance to the antibiotic colistin in intestinal bacteria. According to this article, bacteria with this gene were found in China in humans and animals as well as in foods. The authors attributed the presence of this gene to the frequent use of colistin in Chinese livestock production.

At the beginning of December 2015, the Danish authorities had reported on the detection of the gene in poultry meat samples from Germany. Tests conducted in England and in the Netherlands yielded positive results too. So far, the targeted studies on the presence of the newly described resistance gene undertaken since the appearance of the Chinese publication have thus shown that the resistance gene described in China has been prevalent in Europe for at least a few years.

In Germany, the polypeptide antibiotic colistin is used predominantly for treating intestinal disease in farm animals. In human medicine, colistin is notably used as antibiotic especially for carbapenem-resistant enterobacteria, if they are unresponsive to other antibiotics better tolerated by humans.

To protect themselves from pathogenic bacteria in and on meat, consumers should carefully observe the rules of kitchen hygiene to ensure that no bacteria are transferred from raw meat to other foods. In addition, meat should be thoroughly heated before consumption, i.e. at its core, the food should reach a temperature of 70 °C for at least two minutes.

The BfR has published tips for consumers to protect themselves against food-borne infections in private households (in German):

http://www.bfr.bund.de/cm/350/verbrauchertipps_schutz_vor_lebensmittelinfektionen_im_privathaushalt.pdf PDF-File (2.4 MB)

The BfR has also released a video clip on the subject of kitchen hygiene entitled “What to do with the chicken?”:

http://www.bfr.bund.de/en/what_to_do_with_the_chicken_-192793.html

Information of the Robert Koch Institute on transferrable colistin resistance (in German):

http://www.rki.de/DE/Content/Infekt/Antibiotikaresistenz/Bakterienspezies/Colistinresistenz_E_coli.html

About the BfR

The German Federal Institute for Risk Assessment (BfR) is a scientific institution within the portfolio of the Federal Ministry of Food and Agriculture (BMEL) in Germany. It advises the Federal Government and Federal Laender on questions of food, chemical and product safety. The BfR conducts its own research on topics that are closely linked to its assessment tasks.

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