Gut bacteria in farm animals have become increasingly less resistant to antibiotics over the past ten years in the Netherlands. This is one of the findings of the antibiotic resistance monitoring conducted by the National Institute for Public Health and the Environment (RIVM), Wageningen Food Safety Research (WFSR), Wageningen Bioveterinary Research (WBVR) and Utrecht University (UU). The result of their work is published today in the NethMap/MARAN report.
The antibiotic resistance monitoring in the Netherlands is commissioned by the Dutch government as part of EU legislation. The monitoring program includes humans and animals, as well as food.
Antibiotic resistance is monitored annually in farm animals. For this purpose, the Dutch Food and Consumer Product Safety Authority (NVWA) collects random samples from broilers, pigs and veal calves. These samples are analysed at WBVR to screen for antibiotic resistance. As head of the National Reference Laboratory, Kees Veldman (WBVR) is responsible for monitoring antibiotic resistance in farm animals. He is also key editor of the MARAN report. “In addition to E. coli, our monitoring program also includes Salmonella and Campylobacter bacteria. These bacteria are important causes of food born infections and therefore important to monitor closely from a public health point of view.”
The monitoring shows that the antibiotic resistance of intestinal bacteria has decreased in all farm animals over the past ten years. “What is striking about the results of this report is that antibiotic resistance in broilers has fallen to the lowest level since 1998,” says Veldman. This is in line with the further decline in antibiotic use in broilers. “Figures from the Netherlands Veterinary Medicines Institute show that antibiotic use in broilers has decreased by 31.7 percent in 2021 compared to the previous year.”
Whole genome sequencing
In addition to monitoring antibiotic resistance via phenotypical testing methods, whole genome sequencing was used. Information from this genetic analysis is reported to the European Food Safety Authority (EFSA). “The genetic analysis focuses in particular on the so-called extended spectrum beta-lactamase (ESBL) enzyme that some bacteria produce,” says Mike Brouwer. As a molecular biologist, he is responsible for research into the genetic background of the antibiotic resistances found within the monitoring program.