Photo: National Food Institute, Technical University of Denmark

Considerably fewer resistant bacteria in broiler meat

Tuesday 20 Oct 15


Robert Leo Skov
Overlæge, Statens Serum Institut
+45 32 68 83 48

Considerably fewer resistant ESBL bacteria were found in Danish and imported broiler meat in 2014 compared with the year before. It is the second consecutive year that a fall in the occurrence of this type of bacteria has been registered in Danish broiler meat. However in 2014 the efforts to combat ESBL in the European broiler production could also be detected in imported broiler meat. These are some of the findings in the annual DANMAP report from 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.

The annual DANMAP reports show the prevalence of resistant bacteria in humans, meat and animals. According to the latest report ESBL bacteria have been found in 9% of the Danish broiler meat samples and 25% of the imported broiler meat samples in 2014. This represents a significant decrease in the occurence of ESBL in both Danish and imported broiler meat compared to previous years. In 2011 and 2012 when the occurrence of ESBL was highest in Danish and imported broiler meat respectively, ESBL was detected in approximately half of the broiler meat samples.

ESBL passed down to Danish broilers

Danish poultry producers have not used cephalosporins to treat animals in the broiler production for more than ten years.

”So when resistant ESBL bacteria are nonetheless found in Danish chickens, it is either because they survive in the production system or because they have entered production through imported parent animals of the chickens we eat today. ESBL bacteria can be passed down from from generation to generation,” associate professor Lars Bogø Jensen from the National Food Institute says.

”The fall in the occurance of ESBL bacteria in both Danish and imported broiler meat in 2014 may partly be because of a voluntary discontinuation of the use of cephalosporins at the top of the breeding pyramid abroad. This looks to have had a positive effect on the breeding animals that Danish producers import,” Lars Bogø Jensen adds.

Very few ESBL bacteria in pork and beef 

The occurence of ESBL bacteria in both Danish and imported pork and beef continues to be very low. In 2014 ESBL was only found in one sample of Danish pork out of more than 550 samples of pork and beef that were tested.

Different ESBL types in meat and patients

A random sample of ESBL resistant coli bacteria from meat sold in Denmark shows that only in very few cases are they the same types as those which cause sepsis in Danish patients.

”It does not appear that broiler meat in Denmark is a significant source of sepsis caused by ESBL resistant bacteria,” consultant Robert Skov from Statens Serum Institut says.

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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 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 which causes the antimicrobials to lose their effectiveness. 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 is 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.
23 APRIL 2021