Antibiotic-resistant bacteria in ready-to-eat foods

June 5, 2017, American Society for Microbiology

Research presented at the ASM Microbe 2017 meeting by Bryan Sanchez of California State University-Northridge in Northridge, Calif., show that antibiotic-resistant bacteria are present in many ready-to-eat foods such as fresh produce and dairy products and may serve as a source of human exposure to antibiotic-resistant bacteria. About 2 million people become infected with antibiotic resistant-bacteria annually in the United States, resulting in over $35 billion in additional health care costs. Examining potential ways that humans can be exposed to antibiotic-resistant bacteria can help in understanding how to counter the threat.

Approximately 80% of antibiotics in the U.S. are used by the agricultural industry, mostly for production. Ready-to-eat foods, such as products and , do not undergo a "kill" step such as cooking during preparation, so can either be directly consumed or can contaminate kitchen surfaces or other foods.

The study, conducted by a team of undergraduate student researchers lead by a graduate student (Tabitha Bayangos) in Dr. Kerry Cooper's research laboratory at California State University-Northridge in Northridge, Calif., was a preliminary surveillance aimed at quantifying the antibiotic-resistant bacteria commonly present in ready-to-eat foods. Organic or conventional fresh produce and dairy products were purchased from local grocery stores throughout the San Fernando Valley, Calif. The amounts of total bacteria and of bacteria resistant to eight different antibiotics (ciprofloxacin, tetracycline, erythromycin, chloramphenicol, gentamicin, ampicillin, cefotaxime, and colistin) were quantified "Dairy products were found to have very low levels of antibiotic-resistant bacteria, with yogurt samples tending to have the highest amount," said Sanchez. The highest level of resistance in dairy products was found to be against cefotaxime, a broad-spectrum antibiotic used to treat numerous bacterial infections.

Both organic and conventional produce were found to have on average 10,000 times more antibiotic-resistant bacteria than did dairy products. The highest levels of resistance were again found to be against cefotaxime, as well as the last-resort antibiotic colistin. "Since antibiotics are not commonly used by the produce industry," said Sanchez, "the fruits and vegetables are most likely contaminated with soil, a natural source of antibiotic-resistant bacteria." Sequencing of the 16S rRNA gene for resistant bacterial identification found a variety of genera resistant to each antibiotic, including many that are known to be naturally resistant to those particular antibiotics. "However, we also identified a number of naturally sensitive bacteria that were found to be resistant to the different antibiotics tested. Our study shows that antibiotic-resistant bacteria are naturally present in many ready-to-eat foods such as fresh produce, but even with lower levels are directly consumed. These foods are potential sources of to antibiotic-resistant ," said Sanchez.

Results of the study were presented on June 4 at the American Society for Microbiology (ASM) Microbe conference in New Orleans.

Explore further: Understanding drug-resistant superbugs

Related Stories

Understanding drug-resistant superbugs

July 18, 2016

News reports reveal drug-resistant super bacteria identified as carbapenem-resistant Enterobacteriaceae (CRE) have been found in the waters of Rio de Janeiro where the 2016 Olympics sailing events will be held.

The problem with antibiotics

September 27, 2016

We've all woken up with a sore throat that progresses to a runny nose by the next day. By the third day, we have a hacking cough, a pounding headache from the sinus congestion, and even fevers with chills. We drag ourselves ...

Recommended for you

EPA adviser is promoting harmful ideas, scientists say

March 22, 2019

The Trump administration's reliance on industry-funded environmental specialists is again coming under fire, this time by researchers who say that Louis Anthony "Tony" Cox Jr., who leads a key Environmental Protection Agency ...

Coffee-based colloids for direct solar absorption

March 22, 2019

Solar energy is one of the most promising resources to help reduce fossil fuel consumption and mitigate greenhouse gas emissions to power a sustainable future. Devices presently in use to convert solar energy into thermal ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.