Photo: National Food Institute, Technical University of Denmark

Fewer resistant bacteria in Danish broiler meat

Tuesday 30 Sep 14
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Yvonne Agersø Yvonne Agersø
Seniorforsker
DTU Fødevareinstituttet
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Significantly fewer resistant ESBL bacteria were found in Danish broiler meat in 2013 compared with the year before. However, the occurrence of ESBL bacteria in imported broiler meat remains at the same high level as in 2012. This appears from the annual DANMAP report, which is published by Statens Serum Institut and the National Food Institute, Technical University of Denmark. DANMAP is the Danish integrated antimicrobial resistance monitoring and research programme.

ESBL bacteria are one of the fastest growing resistance problems worldwide. The bacteria are resistant to the type of antimicrobials known as cephalosporins, which are often used to treat life-threatening infections in humans.

According to the annual DANMAP report, which shows the prevalence of resistant bacteria in humans, meat and animals, ESBL bacteria have been found in just over half of all imported broiler meat samples in 2013, which is the same level as in 2012. In comparison, the bacteria have only been found in every fourth sample of Danish-produced broiler meat - a significant decrease compared to 2012, where the prevalence in Danish broiler meat was 36%.

International standards for antimicrobial use are necessary

Danish poultry producers have not used cephalosporins for more than a decade.

”When resistant ESBL bacteria are nonetheless found in Danish broiler meat, it is because they have entered production through imported parent animals of the chickens we eat today. ESBL bacteria are inherited from generation to generation, and until 2012 cephalosporins were used in animals at the top of the breeding pyramid abroad," senior researcher Yvonne Agersø from the National Food Institute explains.

”The situation shows why it is necessary to have international standards for the use of antimicrobials in food production in order to avoid resistance problems in one country creating problems beyond its borders,” Yvonne Agersø emphasises.

”When fewer ESBL bacteria are found in Danish broiler meat in 2013 than the previous years, it is in part because of a voluntary discontinuation of the use of  cephalosporins at the top of the breeding pyramid abroad. This has had a positive effect on the breeding animals that are imported into Denmark,” Yvonne Agersø adds.

Very few ESBL bacteria in pigs at slaughter

The incidence of ESBL bacteria in pigs at slaughter is low in 2013. The bacteria have been found in 5.8% of the samples from slaughter pigs, which is in line with results from the previous two years.

In 2010 Danish pork producers introduced a voluntary stop to the use of cephalosporins. Of a total antimicrobial consumption in pigs of just over 90 tonnes, approximately 3 kilos is cephalosporins.

”Even though the use of cephalosporins is very low, it still represents a considerable increase compared to the previous year when it was 1 kilo. It is important that these antimicrobials are only used when absolutely necessary, so we can maintain the low occurrence of ESBL that we have seen in pigs at slaughter in recent years,” Yvonne Agersø points out.

European surveillance of ESBL from 2015

The EU also takes the problem of ESBL in animals and foods very seriously and in response has initiated mandatory monitoring of this type of resistance in both meat and production animals in Europe. From 2015 all member states must monitor the occurrence of resistance in cattle and pigs as well as beef and pork – and from 2016 also in broilers and broiler meat.

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Since 1995 the DANMAP programme has monitored the use of antimicrobials in humans and animals in Denmark, and the occurrence of antimicrobial resistance in bacteria in animals, people and foods. The organisations behind DANMAP are the National Food Institute, the National Veterinary Institute (both institutes are under the Technical University of Denmark) and Statens Serum Institute. The DANMAP report is prepared by the National Food Institute and Statens Serum Institute.

Find the DANMAP report on DANMAP’s website.

FACTS

Facts about antimicrobial resistance

Treatment with antimicrobials is intended to kill pathogenic bacteria. Unfortunately, antimicrobials also cause the bacteria to protect themselves by developing resistance to the type of antimicrobials that are used to treat them. Resistant bacteria can be transmitted between humans, and bacteria can infect each other with resistance. However, resistant bacteria are poor at surviving if antimicrobials are not present. Therefore, it is important to have an overall focus on using as few antimicrobials as possible for the treatment of both animals and humans.

Bacteria know no borders, therefore antimicrobial resistance in one country can cause problems outside of its borders. As such the use of antimicrobials in both animals and humans is a global problem.

Not all antimicrobials are the same. Some are narrow spectrum and affect only individual groups of bacteria. They are used when you know which bacteria are causing the disease. Others are broad spectrum and affect numerous groups of bacteria at the same time. They can therefore be used to treat a disease before knowing which bacteria are the cause. However, they often also kill useful and harmless bacteria such as bacteria from the intestine, which may lead to the emergence of resistant bacteria.

Not all antimicrobials are equally important in the treatment of humans. WHO has declared a number of antimicrobials to be ’critically important’, because they are the only or one of only a few antimicrobials, which can be used to treat serious or life-threatening infections in humans. These types include carbapenems, third and fourth generation cephalosporins, fluoroquinolones and macrolides.

Facts about ESBL bacteria

Cephalosporins are one of the broad spectrum antimicrobials which are used for the treatment of life-threatening infections. Moreover, ESBL bacteria also become resistant to almost all the common types of penicillin.

The enzymes that cause cephalosporin resistance are called ESBL (extended-spectrum beta-lactamase). Cephalosporin-resistant bacteria, such as e.-coli, salmonella and klebsiella, are therefore called ESBL-producing bacteria or simply ESBL bacteria.