Study Finds Antibiotic-Resistant Staph in U.S. Food Supply

Study Finds Antibiotic-Resistant Staph in U.S. Food Supply.

Study Finds Antibiotic-Resistant Staph in U.S. Food Supply

April 27, 2011

The ongoing debate regarding antibiotics use with animals destined for the table has centered on whether drug-resistant organisms created on farms travel from the farm to humans. According to a newly published study (PDF), they do.

Researchers from the Center of Food Microbiology and Environmental Health at the Translational Genomics Research Institute in Flagstaff, Arizona, found one in four packages of meat and poultry purchased contained multi-drug resistant staph.

This is the first such study of drug-resistant staph in the U.S. food supply. The researchers say it remains unknown whether humans can be infected from raw meat.

Meat producers reportedly provide healthy animals with low doses of antibiotics for several reasons. The two leading rationales are to promote young animals’ growth and to reduce the spread of infections in factory farm operations.

The researchers purchased packaged meats — 136 packages of ground beef, chicken breasts and thighs, pork chops and ground pork, and ground turkey — in five U.S. cities. Of the meat samples tested, 47 percent were contaminated with Staphylococccus aureus. Of those, more than half were resistant to three or more antibiotics.

Representatives from the turkey and pork producers contend their products are safe. “Staphylococcus aureus is a very common bacteria found in the environment, and is one of the most common found on human hands. It rarely causes any health problems,” says Hilary Thesmar, director of scientific and regulatory affairs for the National Turkey Federation in Washington, D.C., in a statement reprinted by WebMD.

“Contamination by human hands is a likely source of contamination of the products in this study,” Thesmar says. “The most important message for consumers is to follow proper food safety methods, such as washing your hands and cooking meat and poultry thoroughly. Following good food safety practices will ensure that consumers continue to enjoy safe, high-quality, and nutritious turkey products.”

Even so, there is no conclusive data showing these measures will curb or prevent the spread of staph. These forms of staph live on the skin and can continue to live there without causing illness for an unpredictable amount of time. The risk of contamination has not been studied.

Antibiotic resistance’s cost to medicine in the US has exceeded the billion dollar mark, according to The Los Angeles Times. Among the most egregious contributors to this is the predominance of methicillin-resistant Staphylococcus aureus (MRSA), which is a dangerous antibiotic-resistant infectious disease.

Although there is a system in place in the U.S. that looks for antibiotic-resistant bacteria, it does not look for MRSA. Even so, testing food for MRSA would not have found the various multi-drug resistant strains revealed in this latest study because they were not MRSA.

This newest work supports previous research from The Netherlands that found live poultry and meat carried identical, highly drug-resistant E. coli. This led them to conclude that antibiotic resistance seems to be moving from poultry raised with antibiotics to humans via food. The study specifically looked at extended-spectrum beta-lactamase resistance (ESBL).

The Los Angeles Times notes that antibiotic resistance has long been a problem. In 1969, a British government study recommended banning antibiotics. “The first observation that giving antibiotics to animals spreads antibiotic-resistant bacteria to humans was made in 1976, and there has been a steady accumulation of evidence since,” wrote Maryn McKenna, author of Superbug and Beating Back the Devil, in a March Wired article.

Organizations including World Health Organization, the Centers for Disease Control and Prevention, the American Medical Association, and others support restricting antibiotic use, including for treating humans. This new study was partially funded by the Pew Charitable Trusts, which also studied the issue in its Pew Commission on Industrial Farm Animal Production.

“For more than 50 years microbiologists have warned against using antibiotics to fatten up farm animals. The practice, they argue, threatens human health by turning farms into breeding grounds of drug-resistant bacteria,” wrote Scientific American’s editors in a March 30, 2011, editorial.

“Although even the proper use of antibiotics can inadvertently lead to the spread of drug-resistant bacteria, the habit of using a low or subtherapeutic dose is a formula for disaster: the treatment provides just enough antibiotic to kill some but not all bacteria. …  The data from multiple studies over the years support the conclusion that low doses of antibiotics in animals increase the number of drug-resistant microbes in both animals and people. …Stronger measures to deprive drug-resistant bacteria of their agricultural breeding grounds simply make scientific, economic and common sense.” (Article Link)

By Linda Dailey Paulson

Image by nate steiner, used under its Creative Commons license.