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In September we published the latest version of an article called “Prevalence of antibiotic-resistant E. coli in retail chicken: comparing conventional, organic, kosher, and raised without antibiotics”. The study showed that Kosher chicken had higher levels of antibiotic-resistant E. coli than conventional, organic, or RWA chicken. This piqued the interest of several media outlets, and after it passed peer review, the article continued to receive coverage throughout October and early November, including in the Jewish Daily Forward and on the New York Times’ Well blog. The combination of microbiology, food, and religion made the paper a source of much discussion, and some media also focused on the fact that the first author, Jack Millman, is still in high school!

Since there has been so much interest in the paper, we caught up with two of the authors, Lance Price (Department of Environmental and Occupational Health, George Washington University, Washington DC) and Jack Millman (Horace Mann School, Bronx, NY), to find out more about the study:

EA: Do you have any idea what could cause the difference in the amount of resistance in bacteria found on Kosher chicken compared to the other samples? Or do you have any suggestions for where to start looking to find these answers?

Lance Price: Antibiotic-resistance ultimately comes down to antibiotic use by the producers. It could be a shadow of historic antibiotic use, but it could also reflect use in the breeder chickens, the ones laying the broiler eggs, broiler egg injections, egg dips, injections of the chicks, or antibiotics in the feed or water. The latter (feed and water) is the only place where antibiotics are regulated under the organic standards, and as far as I can tell the Kosher guidelines say nothing about antibiotics.

Image from the paper showing the difference in drug resistance between kosher chicken and the other types of chicken tested.

EA: I was instantly intrigued by this sentence in the methods section: “During April–June 2012, raw chicken was purchased from supermarkets, butcher shops, specialty stores, and food distributors in the greater New York City area.” What’s the story here? How many shops did you cover in one trip? Did you vary the types of chicken collected on one day? Did you need to then immediately ship the samples to the lab in Arizona?

Jack Millman: We carefully chose brands of chicken in each of the four categories (Kosher, organic, raised without antibiotics, and conventional) to best represent the country. They were the largest, most widely available brands. Our shopping actually occurred on Saturdays and Sundays because some kosher outlets are closed on Saturdays. (Although most Kosher chicken is really bought in grocery stores anyway). We would pretty much shop all day and get as many stores that were open as possible. Normally, we achieved this or came close to it.

We bought chicken that contained a drumstick with skin for each sample. For each of the five waves we bought the same exact brands and types. The actual stores stayed much the same but this was not relevant to the analysis and consumer behavior as it is the product itself that we were focused on. The chicken remained chilled for a maximum of two days and then was shipped overnight in special coolers in its own packaging to Arizona.

LP: All products were immediately put in a cooler and kept on ice until shipment. They were then shipped overnight in the ice chests and processed immediately upon arrival at the lab.

EA: This story has been quite popular online and in the media. What has the media attention been like?

LP: Fun for the most part. Jack has been getting a lot of kudos for his good ideas and hard work. People get graduate degrees in some universities for this level of work — this kid is in high school!

EA: Have you looked at any of the comments on the coverage your paper got online? I noticed for example that someone mentioned that the fact that the chicken was purchased on a Saturday might make a difference. Can you respond to that?

LP: I try not to look at online comments. The date of purchase or time-to-process would have no impact on whether or not the E. coli was resistant to antibiotics. If they hadn’t been kept cold (which they were), then there could have been a difference in bacterial load, but that’s not what we measured.