A study conducted at the Pennsylvania Department of Health, along with the Penn State College of Medicine and the FDA, found that meat from conventionally-raised poultry harbored almost twice as much multidrug-resistant Salmonella bacteria as meat from antibiotic-free or organic poultry. The study was presented at IDWeek 2019.
Consuming Salmonella-contaminated meat is one of the most common causes of foodborne illness. Since this infection is treated with antibiotics, when the pathogen is resistant to many different commonly used drugs, the illness can be more serious and dangerous.
The overuse and misuse of antibiotics in both humans and animals raised for food leads to antibiotic resistance. The FDA has issued guidance documents, which are not legally binding, to try to limit the use of medically important antibiotics in animals.
In the first study, researchers reviewed data from chicken and turkey randomly purchased from stores in Pennsylvania between 2008 and 2017. They found that 280 of the 2,733 samples (10.2%) of conventionally raised poultry were contaminated with non-typhoidal Salmonella species, compared to 40 of the 748 poultry samples (5.3%) labeled antibiotic-free.
They also found that 55% of Salmonella cultures from conventionally raised poultry were resistant to three or more antibiotics compared to 11 of 40 Salmonella cultures (28%) from poultry raised without antibiotics. And, more alarmingly, the researchers found that 24.3% of the cultures from conventional poultry, and 7.5% of the cultures from antibiotic-free poultry contained a gene that makes Salmonella infections more difficult to treat with the only class of antibiotics used in children.
Xin Yin, lead author of the study and PhD candidate at Penn State College of Medicine said, “Although contamination of retail poultry was found in both conventionally raised and antibiotic-free samples, our results show that Salmonella in poultry produced without antibiotics – based on packaging claims – were significantly less resistant to antibiotics compared with poultry raised using conventional methods. The key message here for consumers or the average person is that, when you go to grocery stores to purchase poultry meat, you should read the antibiotic-related production claims, and think about the rate of antibiotic-resistant Salmonella before you make the purchase.”
In addition to these alarming numbers, these genes associated with high antibiotic resistance can be shared by Salmonella bacteria with other bacteria. This can lead to multidrug-resistant infections in other pathogens.
The second study focusing on multidrug-resistant bacteria found that 96 of 2,520 poultry, ground beef, and pork chop samples purchased during 2015 through 2017 from randomly selected stores in Pennsylvania contained non-typhoidal Salmonella. Not much more information is available about that study, except for the fact that 29.2% were resistant to three or more antibiotic classes, and four contained genes resistant to eight antibiotic classes.
