Bacteria in animals can easily pass to humans when we consume contaminated meat or milk or eat produce that’s been contaminated by animal waste. The resulting infections can lead to potentially dangerous illnesses such as salmonellosis and campylobacteriosis. Now a new report from Europe shows that such bacteria—which include Salmonella, Campylobacter, and E. Coli—are becoming even more resistant to antibiotics.
The report, released in February 2019 by the European Food Safety Authority (EFSA) and European Centre for Disease Prevention and Control (ECDC), analyzed 2017 data submitted by 28 European Union member countries. It looked at the prevalence of antibiotic resistant bacteria in samples of Salmonella, Campylobacter, and E. coli taken from humans, young pigs and calves under one year old, and meat derived from those animals. (The E. coli samples came only from animals or meat.)
Overall, the report found a high prevalence of antibiotic-resistant bacteria across both human and animal-derived samples. Among the key findings:
- Most countries reported that Salmonella in humans is increasingly resistant to fluoroquinolones, a class of antibiotics that includes ciprofloxacin (Cipro), and a high proportion (28 percent) of Salmonella found in humans showed multidrug resistance, or resistance to three or more antibiotics.
- Among Campylobacter, “high to extremely high” proportions of bacteria were found to be resistant to ciprofloxacin and tetracyclines. In some countries, resistance to fluoroquinolones is so high in Campylobacter that these drugs no longer work for the treatment of severe campylobacteriosis cases.
- About 60 percent of E. coli isolated from young pigs (called “fattening pigs”) and 43 percent of E. coli isolated from calves were resistant to at least some antibiotics, with especially high levels of resistance to tetracyclines, sulfamethoxazole, ampicillin, and trimethoprim.
The findings on growing antibiotic resistance among these bacteria—known as “zoonotic bacteria” because they pass from animals to humans—echo those from previous EFSA and ECDC reports. In a press release accompanying the new report, the EU’s Commissioner for Health and Food Safety stated, “The report released today should ring—again—alarm bells. It shows that we are entering into a world where more and more common infections become difficult—or even sometimes impossible—to treat.”
About zoonotic infections
About 60 percent of all human infections are zoonotic. In the U.S., Salmonella, Campylobacter, and E. coli are responsible for millions of infections each year, with the resulting illnesses ranging from mild to life-threatening. Humans can contract the infections directly from pigs, poultry, and cattle or from eating or handling contaminated food or water. Drinking unpasteurized ("raw") milk is another cause. The diseases can be especially serious for children, elderly people, and those with compromised immune systems.
The growing global resistance to antibiotics in zoonotic bacteria means that human infections once easily treatable by antibiotics may no longer respond to those drugs, requiring doctors to turn to expensive and sometimes less effective “last resort” antibiotics—the use of which in turn feeds resistance to those drugs, raising the specter of a “post-antibiotic future” in which even the most powerful antimicrobial agents simply don’t work anymore.
Many previous reports, including a large World Health Organization report released in 2017, have documented resistance to multiple antibiotics in other dangerous bacteria, including those that cause tuberculosis, gonorrhea, and deadly hospital-acquired infections. A chief cause of the growing problem of antibiotic resistance is the indiscriminate use of antibiotics in livestock. Overuse of antibiotics in humans—for example, prescribing antibiotics for a viral infection such as a cold, which the drugs can’t treat—also contributes to resistance.
Aside from highlighting the urgency of curbing unnecessary antibiotic use, the new findings highlight the importance of taking steps to prevent infections from animals and contaminated food. This includes frequently washing your hands (including after contact with farm animals), following all recommended food-safety practices when preparing meat and poultry, and avoiding unpasteurized (“raw”) milk products. To help discourage the overuse of antibiotics in livestock, look for meat or poultry that was raised with zero antibiotics. You can also make an effort to support restaurants that are going antibiotic-free.