Swedish study looks at antibiotic resistance in Campylobacter on chicken
Antibiotic-resistant Campylobacter is more common in foreign chicken than domestic meat, according to an analysis in Sweden.
Research also found that the majority of Campylobacter infections in patients infected abroad were resistant to groups of antibiotics that are important in healthcare. However, no bacteria from meat or patients were resistant to a group called macrolides which is the first choice for treating serious infections. This group includes azithromycin and erythromycin.
Antimicrobials – including antibiotics – are medicines used to prevent and treat infections in humans and animals. Antimicrobial resistance (AMR) occurs when bacteria, viruses, fungi and parasites no longer respond to medications that make infections more difficult to treat.
The National Food Administration and the Swedish Public Health Agency investigated how common it was to Campylobacter from chicken meat in stores and in patients to be antibiotic resistant. A total of 284 isolates from patients and 111 from chicken meat were included in the study.
Sweden has generally seen lower antibiotic use for both humans and food-producing animals compared with other countries. Most people with a Campylobacter infection recover after about a week and antibiotics are given only in severe and long-term cases.
The work showed that 85 percent of Campylobacter from Swedish chicken meat and 58 percent from foreign meat were sensitive to important antibiotic groups.
A total of 76 percent of those infected in Sweden had Campylobacter, which was not resistant to front-line antibiotics, but for those infected abroad, the figure was 21 percent.
Results for meat
The same types of resistance markers to the clinically important classes of antibiotic quinolones, tetracyclines and aminoglycosides were found in Campylobacter jejuni from chicken meat and patients.
After a major outbreak linked to domestic chicken meat in 2016-17, the Swedish Public Health Agency and the National Food Administration compared Campylobacter from chicken meat in the retail trade and Swedish patients genetically. Similar minor outbreaks were registered in 2018 and 2020.
In 67 of the 79 isolates of Campylobacter jejuni from Swedish chicken meat, no mutations or genes were identified that encode resistance to the important classes of macrolides, quinolones, tetracyclines or aminoglycosides. However, 14 out of 24 isolates from meat from other countries lacked such resistance determination factors.
For Campylobacter jejuni from Swedish, conventionally bred chicken, 40 out of 45 isolates lacked genes or mutations for resistance to quinolones, macrolides, tetracyclines or aminoglycosides. For the 34 isolates from organic Swedish meat, 27 did not have such resistance markers.
A total of 87 different sequence types were detected in the 375 isolates of Campylobacter jejuni from chicken meat and patients.
Findings from patients
For Campylobacter jejuni from patients, 162 of the 212 isolates from domestically acquired infections and 11 of 53 isolates from travel-related cases contained no such evidence of resistance.
Multidrug resistance was identified in only three isolates from patients, two of whom had probably been infected abroad.
The most common resistance determination factor in isolates from chicken meat and patients were genes for resistance to beta-lactams, which are not recommended for the treatment of Campylobacter infections. The main type of resistance identified among the clinically important classes of antibiotics was a mutation, which confers resistance to quinolones, followed by a tetracycline resistance gene and an aminoglycoside resistance gene.
The purpose of the study was to increase knowledge about the resistance situation for Campylobacter in Sweden and to obtain a basis for source attribution, risk assessment and management of the pathogen in chicken meat.
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