It’s a new, if still debatable, mystery of modern science: Why would kosher chickens harbor much higher levels of potentially dangerous antibiotic-resistant bacteria than nonkosher chickens?
The authors of a recent study that found this are just as stumped as anyone.
“Nobody expected it would be any higher than conventional chicken,” said lead author Jack Millman, a 17-year-old senior at Horace Mann School in the Bronx. Millman thought to investigate whether kosher food is healthier after his sister Jessie’s bat mitzvah in Israel a few years ago. His co-authors include his uncle, Bruce Hungate, a professor of biological sciences at Northern Arizona University, and Lance Price, a professor of environmental and occupational health at George Washington University.
The researchers published their study in F1000Research , a London-based online life sciences journal in which referees critique articles after they are posted online. The referees’ critiques are then posted alongside the original article, comments from registered users and revised versions of the original article based on the critiques. All versions of the article and accompanying critiques remain available and linked online.
The study Millman initiated, which analyzed 213 drumsticks from raw chickens, almost all of them bought from Manhattan stores, found higher levels of an antibiotic-resistant strain of E. coli bacteria in kosher chickens than in nonkosher chickens.
Still, no one is saying that religious Jews should give up one of the staples of Sabbath meals. It’s only one study, which will require replication to be confirmed. And some of the top scientists in the field say they’re hard-pressed to explain the finding.
“Why should the kosher chickens have any more [antibiotic resistant bacteria] than the conventional? What’s different?” asked Stuart Levy, director of the Center for Adaptation Genetics and Drug Resistance, at Tufts University School of Medicine. Levy, who keeps kosher, was among the first scientists to document the transfer of antibiotic-resistant bacteria from animals to farm workers.
Antibiotic-resistant bacteria are a growing public health concern. Each year, at least 2 million Americans become infected with antibiotic-resistant bacteria and 23,000 of them die, according to the Centers for Disease Control.
Many experts point to the heavy use of antibiotics on animals in modern-day industrial agriculture as a culprit in the phenomenon’s rise. Antibiotics are widely used because they are thought to help grow bigger chickens, the theory being that the drugs free up the birds’ energy for building muscles instead of fighting infections.
“I think it’s an abhorrent use of our lifesaving antibiotics,” said co-author Price, a non-Jew who shops for chickens raised without antibiotics at Whole Foods.
In a report released in September, the CDC called antibiotic-resistant bacteria in food-producing animals a problem of “particular concern because these animals serve as carriers. Resistant bacteria can contaminate the foods that come from those animals, and people who consume these foods can develop antibiotic-resistant infections.”
Thoroughly cooking chicken kills bacteria. But Price noted that at least half the cases of food poisoning from E. coli result from cross-contamination: People handled raw chicken and then didn’t wash their hands before making a salad, or they didn’t scrub their cutting board between preparing raw chicken and slicing vegetables for a salad. Most commonly, E. coli causes urinary tract infections — which need to be treated with antibiotics.
Resistance occurs as a result of natural selection when spontaneous mutations in bacteria enable some to withstand antibiotics. These strains spread and become ubiquitous as other strains fall to the antibiotics. Resistance can be transferred from a single bacterium to others of the same kind as well as to other kinds of bacteria.
But this chicken study is doubly puzzling because normally such resistant bacteria would thrive in a place which liberally used antibiotics, but chickens raised without antibiotics were found to carry as much of the antibiotic-resistant E. coli in question as those given antibiotics.
Furthermore, Empire Kosher, whose drumsticks were among those used in the study, started phasing out antibiotics in its chickens in mid-2008. Since June 2010, none of its chickens has been raised with antibiotics, said Greg Rosenbaum, who from 2006 until last October was Empire’s CEO. (Millman and his mother collected chickens for the study from April 2012 to June 2012.)
The study itself did not specify the brands used; that information came from co-author Price in his interview with the Forward. In fact, Price said, more Empire chickens were analyzed than any other kosher brand because of the company’s dominance in the market.
Nevertheless, Empire spokesman Eli Rosenfeld declined to comment on Millman’s research, on the grounds that the brands used in the study remain unpublished. “We don’t have a comment because we don’t know what products or what brands they tested,” he said.
On average, Empire processes 240,000 chickens a week at its plant in tiny Mifflintown, Pa. But according to Rosenbaum, today Empire only uses chickens from its own network of hatcheries and farms, where they are fed only antibiotic-free feed from Empire’s own feed mill. Farms that raise Empire’s antibiotic-free chickens do not raise chickens for any other producers, Rosenbaum said.
Empire stopped raising chickens with antibiotics because of consumer demand, said Rosenbaum, who today is president of Palisades Associates, a private equity firm in Bethesda, Md.
Other kosher companies, of course, may well use chickens raised with antibiotics. But according to kosher industry experts Timothy Lytton and Joe Regenstein, “There is no reason to believe that antibiotic use is more intensive, or exposure to antibiotic-resistant bacteria more likely, in the production of chickens for the kosher market.”
In an opinion piece for the website Food Safety News, Lytton, a professor at Albany Law School and author of “Kosher: Private Regulation in the Age of Industrial Food” published recently by Harvard University Press, and Regenstein, a professor of food science at Cornell University, speculated that the lower levels of bacteria in nonkosher chickens could be attributable to the fact that nonkosher chickens are immersed in scalding water to make it easier to remove their feathers. Kashrut prohibits chickens from being cooked until after the meat has been soaked and salted to remove the blood.
“What is the temperature sensitivity of these E. coli ? How salt-sensitive are they?” Regenstein asked in an interview with the Forward. “It’s an interesting paper. In the short term, it doesn’t tell anybody anything that’s really useful.”
Study co-author Price acknowledged that the study has no take-away message for consumers.
“It’s not something that can be solved by consumer choice,” he said. “The public needs to know more about how and why antibiotics are used on food animals to produce meat and poultry.”
Levy, co-founder and president of the Alliance for the Prudent Use of Antibiotics , opined: “The bottom line is, we should remove antibiotics from the raising of chickens and other animals. The potential harm by propagating resistant bacteria in the farm environment is too great.”
Contact Rita Rubin at firstname.lastname@example.org