Kosher chicken has the highest frequency of antibiotic-resistant E. coli at nearly twice that of conventional products, according to a US study.
This goes against conventional thinking that it is perceived as clean and same to consume.
Hungate et al examined the occurrence of antibiotic-resistant E. coli on raw chicken marketed as conventional, organic, kosher and raised without antibiotics (RWA).
Strains of E. coli isolated from samples in RWA tended to be resistant to fewer drugs but the difference was not significant versus conventional and organic.
The results indicate that production methods influence the frequency of antibiotic-resistant E. coli on poultry products available to consumers.
Researchers assayed for generic E. coli and did not assess virulence or virulence group assignments for each sample, so some of the bacteria found may not be harmful to humans.
Antibiotic type resistance
From April to June 2012, they purchased 213 samples of raw chicken from 15 locations in New York City and screened E. coli isolates from each sample for resistance to 12 common antibiotics.
Over half of all strains collected exhibited resistance to one or more antibiotics: 55% (conventional), 58% (RWA), 60% (organic), and 76% (kosher) chicken samples.
Resistance to cefazolin was most common (41.3%), followed by ampicillin (31.5%), tetracycline (30.4%), and ampicillin sulbactam (19.6%).
Some resistance was detected for cefoxitin, (12.5%) and gentamicin (10.9% of strains), but no strain was resistant to amikacin, the other aminoglycoside tested.
For quinolones, some (3.3%) of strains were resistant to nalidixic acid, but none was resistant to ciprofloxacin.
Resistance was low (3.3%) for trimethoprim sulfamethoxazole, the one folate pathway inhibitor tested, and was absent for imipenem, the one carbapenem tested.
“The higher resistance found in isolates from kosher chicken, and the distinct antibiotic-resistance profile suggests that use of antibiotics in the kosher production chain is common and that it may be more intensive than use of antibiotics among conventional, organic, or RWA practices,” said the researchers.
“It is not immediately obvious where in the kosher chicken production process antibiotic use might be more prevalent, or where exposure to antibiotic-resistant organisms is more likely.”
More studies are needed to test whether antibiotic resistance among kosher products is consistently higher than conventional and other categories, said the researchers.
“Nevertheless, our study offers insight into another area of the food production system increasing the exposure of people to microorganisms that are resistant to antibiotics.
“In addition to regulation, more consistent surveillance or auditing would add of consumer protection, enabling improved purchase decisions based on price and health benefits guided by meaningful labels.”
It was funded by the Merriam-Powell Center for Environmental Research and the Ecosystem Science & Society Center at Northern Arizona University.
Source: F1000 Research
“Prevalence of antibiotic-resistant E. coli in retail chicken: comparing conventional, organic, kosher, and raised without antibiotics”
Authors: Jack M Millman, Kara Waits, Heidi Grande, Ann R Marks, Jane C Marks, Lance B Price, Bruce A Hungate