Poultry, beef and pork are ongoing sources of drug-resistant bacteria and may lie at the root of thousands of illnesses in people who eat the products, a flurry of investigations has found.

To most people, the notion of drug-resistant bacteria is largely associated with hospitals, or possibly even high school gyms. School-related cases of MRSA crop up episodically, as was the case on Long Island in December at Rocky Point High School, where several students were infected.

Yet an underappreciated source of drug-resistant bugs persists in the meat supply, studies show, contaminating a variety of cuts to whole animals, including broiler chickens and the amalgam of muscle and fat sold as ground beef. Thorough cooking destroys the germs.

The latest assessment of drug-resistant germs in the food supply was released recently by the Centers for Disease Control and Prevention. It is one of multiple investigations zeroing in on retail meats. The CDC's estimate: 440,000 people get sick annually because of drug-resistant germs in the meat supply.

Investigators with the agency's National Antimicrobial Resistance Monitoring System conducted the analysis, which examined a rogues gallery of bugs that turn up frequently, particularly campylobacter and salmonella.

Problem across nation

advertisement | advertise on newsday

With all 50 states showing evidence of drug-resistant contaminants, experts defined the problem as a public health issue of growing concern.

"If a foodborne illness is caused by antibiotic-resistant bacteria, it is much harder to treat," Sen. Kirsten Gillibrand (D-N.Y.) said in a statement. She has authored legislation to eliminate antibiotics in animal feeds.

Cattle are prepared for transport after USDA inspection in Laredo, Texas. Photo Credit: AP / Eric Gay

In 2013, the U.S. Food and Drug Administration called on the pharmaceutical industry to voluntarily relabel a vast number of antibiotics and restrict their use in animals farmed as food. The medications -- widely used to treat human infections -- have long been used to fatten healthy animals.

@Newsday

Officials with the North American Meat Institute, an industry organization that represents producers, address the issue on its website and attribute the growing antibiotic resistance crisis to an overprescription of the drugs by doctors to their patients.

Advocates for changes in animal farming blame meat producers for needlessly dosing animals farmed for their meat.

"We know that the misuse of antibiotics contributes to resistance," added Gillibrand, who has accused the poultry industry of using the drugs to help fatten the birds for market.

Some poultry producers have begun bending to the pressure. And while they promise to stop dosing chickens and turkeys for nonveterinary medical reasons, they acknowledge it won't happen overnight.

In April, poultry giant Tyson Foods Inc. announced it would eliminate antibiotics by September 2017. But in May, Joe Sanderson, chief executive of Sanderson's Farms, another major poultry producer, went on record saying the use of human antibiotics would not be reduced in his chickens. Sanderson's chickens are billed as 100 percent natural.

advertisement | advertise on newsday

Earlier this month, Foster Farms stated it has already eliminated antibiotics critical to human health and is working toward eliminating still others.

Foster Farms was tied to a long-running outbreak of multidrug-resistant salmonella that sickened 634 people nationwide in 2013 and 2014. Perdue Farms, meanwhile, touts that 95 percent of its chickens are free of antibiotics.

About one-third of all chicken breasts sold in the United States are tainted with any one of multiple salmonella strains, often drug-resistant, Gillibrand said earlier this year.

Survival of the fittest

Dr. Pascal Imperato, founding dean of SUNY Downstate's School of Public Health in Brooklyn, defines resistant bacteria as microbes capable of thwarting one or more antibiotics through an array of genetic mechanisms.

advertisement | advertise on newsday

Imperato, a former New York City health commissioner and 33-year resident of Manhasset, describes those mechanisms as Darwinian survival-of-the-fittest strategies that bacteria employ to fend off the drugs.

But with few new antibiotics in the pharmaceutical pipeline to provide doctors with better options, the bacteria seem to be winning the war against the drugs that remain, some experts say.

Three years ago, for example, federal scientists reported a tenfold increase in multi-drug-resistant salmonella on chicken breasts alone, the most widely consumed meat product in the country.

Yet, poultry isn't the only source of resistant bacteria. The newly released CDC data suggest pork and beef frequently carry drug-resistant strains, too.

Investigators found that multidrug resistance in a common salmonella strain oddly dubbed "I4,[5],12:i" more than doubled within a two-year time span. Illnesses occurred after exposure to contaminated pork and beef.

Resistance rose from 18 percent in 2011 to 46 percent in 2013, the CDC's monitoring system found. The salmonella strain showed resistance to four types of drugs -- ampicillin, streptomycin, the sulfonamides and the tetracyclines.

The good news, according to the CDC, is that multidrug resistance in a variety of salmonella strains has remained steady over the past couple of years, causing about 10 percent of human infections involving drug-resistant bugs, agency scientists found.

Still, some experts say the meat supply should receive more scrutiny.

"The world is covered in a thin layer of poo," microbiologist Lance Price said, referring to crowded conditions in which livestock are raised, often in the fecal matter of multiple animals. People are exposed to resistant bugs when they purchase meats derived from the animals, he said.

Lets animals get bigger

An overuse of antibiotics may help keep animal infections low, allowing them to grow bigger, Price said, but the result is emboldened bacteria.

Price, a microbiologist at George Washington University, theorizes that rising rates of drug-resistant urinary tract infections in people may be inextricably linked to resistant microbes common in the food supply.

He theorizes such a link because a few years ago he demonstrated the association is possible.

In Flagstaff, Arizona, he was able to directly trace drug-resistant germs from grocery store meats to the urinary tract infections of people who had been hospitalized. He narrowed his research to grocery-purchased meats within a specific radius and tested patients treated at health care facilities nearby.

Using genetic technology, Price obtained DNA fingerprints from retail meats and poultry. He then gathered detailed genetic information on the bacteria infecting patients with urinary tract infections. Stunningly, the DNA fingerprints from the grocery products and the hospital specimens matched, he said.

Price found the meats and the patients all had the same strains of E. coli, suggesting the germs were derived from a common food source.

A significant portion of urinary tract infections may be linked to bacteria in the food supply, Price said, although he is not yet ready to extrapolate his findings from Arizona to other states. Nevertheless, he said much of the evidence already exists.

"There has been a rise in resistant bacteria in food animal production," Price said, "and a rise in resistance in urinary tract infections. And the bacteria [in both cases] are usually resistant to the same drugs."