The study compared samples from conventional, kosher, organic and raised-without-antibiotics (RWA) chicken in order to assess and compare the frequency of contamination with antibiotic-resistant E.coli. Samples were taken from multiple brands of chicken in multiple stores across New York City.
Comparison of the data revealed that while there was little variation in the extent of antibiotic resistance between brands, there was a difference between the method of production. Most notably, they found that strains of E.coli isolated from kosher chicken samples were resistant to more drugs than those found in conventional chicken.
“The increased resistance of E.coli in kosher chicken compared to conventional was surprising, because, while kosher does not stipulate anything about antibiotic use, kosher is perceived as clean and safe to consume,” said the study.
The researchers reflected that the increased antibiotic resistance of the bacteria found in kosher chicken suggested the use of antibiotics in the kosher production chain was common and “may be more intensive than use of antibiotics among conventional, organic, or RWA practices”.
Conventional vs organic
Interestingly, the study found no significant difference between antibiotic resistance in E.coli found in conventional and organic chicken. “Our finding that the frequency of antibiotic resistant strains of E.coli on organic poultry did not differ significantly from conventional reflects some past studies in this area, which have found no difference in antibiotic resistance between organic and conventional practices,” it said.
However, it did find that RWA chicken had lower antibiotic resistance than both conventional and organic. “The distinction between USDA organic from USDA RWA may be important, given that organic chicks can receive antibiotics via in-ovo injections and during the first day of life,” said the researchers.
“Previous studies have provided unequivocal evidence that even in-ovo injection of antibiotics can affect the susceptibility of the bacteria that contaminate poultry products. With a larger sample, the tendency for E.coli isolated from RWA samples to have lower frequency of antibiotic resistance than other categories may emerge as significant.”
More studies needed
Recognising that their study focused on a limited geographical area, the researchers concluded that more studies should be done to assess whether antibiotic resistance among kosher products was consistently higher than conventional and other categories.
However, they added that the study’s findings were “consistent with the suggestion that some ‘niche market’ products, while perceived to be safer, may have higher incidence of foodborne pathogens compared to conventional products”.