Salmonella Risk Lower in Organic or Antibiotic-Free Poultry

Marcia Frellick

October 03, 2019

WASHINGTON, DC — Meat from chicken and turkey raised conventionally is twice as likely to contain Salmonella as poultry labeled organic or antibiotic-free, new research indicates.

In addition, Salmonella from conventional poultry is significantly more likely to be resistant to antibiotics.

There are 100,000 infections every year in the United States that are attributed to antibiotic-resistant Salmonella, investigator Xin Yin, a doctoral student at Penn State College of Medicine in Hershey, reported here at IDWeek 2019.

One reason he and his team looked at poultry, Yin said, is because consumption is so high in the United States. Each American consumes about 95 pounds of chicken and 16 pounds of turkey each year, according to the National Chicken Council.

Because antibiotic use in animals can breed antibiotic-resistant bacteria that can be transferred to humans, "medically important antibicrobial drugs should only be used in animals when necessary for the treatment, control, or prevention of specific disease," according to the US Food and Drug Administration.

For their study, Yin and his colleagues evaluated antimicrobial susceptibility in poultry and conducted whole-genome sequencing as part of the National Antimicrobial Resistance Monitoring System for Enteric Bacteria (NARMS), which tracks changes in the susceptibility of certain enteric bacteria found in people, retail meats, and food animals.

The team isolated 320 Salmonella strains from 3481 poultry samples bought from randomly selected retail outlets in Pennsylvania from 2008 to 2017. They used food labels to identify conventional and antibiotic-free meat.

The presence of Salmonella was significantly higher in the 2733 samples of conventional poultry than in the 748 samples of antibiotic-free poultry (10.2% vs 5.3%; < .0001).

And Salmonella isolated from the 280 samples of contaminated conventional poultry was more likely to be resistant to at least three antibiotics than that isolated from the 40 samples of contaminated antibiotic-free poultry (55.0% vs 27.5%; = .0011).

Salmonella from conventional samples was significantly more likely than that from antibiotic-free samples to be resistant to four drug classes, including those used to treat postoperative infections (= .006).

Of the 280 isolates from conventional samples, 68 (24.3%) contained the bla CMY-2 gene, which makes Salmonella difficult to treat. Of the 40 isolates from antibiotic-free samples, three (7.5%) contained that gene.

These findings might prompt consumers to give more thought to poultry labels and weigh the risks against the typically higher prices for organic and antibiotic-free meats, said Federico Perez, MD, an infectious disease specialist at the Louis Stokes Cleveland VA Medical Center.

"Our food supply is remarkably safe thanks to the efforts of surveillance from our public health agencies," he said. Still, consumers should push for regulations so that antibiotics are only used in humans and agriculture when they are essential.

The Need for Proper Preparation

This study reinforces the need to handle meats carefully, such as preparing poultry away from other foods, using separate utensils, washing hands before touching other foods or surfaces, and cooking to proper temperatures, Perez told Medscape Medical News.

Disease caused by Salmonella affects more than 1 million Americans each year, and about 25,000 people will require hospitalization. Resistance is eating away at options for the treatment of salmonellosis, which makes it a serious threat to public health, he said.

About 450 Americans die from Salmonella each year, according to the Centers for Disease Control and Prevention.

People at elevated risk for severe Salmonella infection include those who have had heart disease, children younger than 5 years, and adults 50 years and older who have suppressed immune systems.

Yin has disclosed no relevant financial relationships. Perez reports receiving support from Pfizer and Merck.

IDWeek 2019: Abstract 102. Presented October 3, 2019.

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