Antibiotics and the Chicken Connection

Each year about 2.4 million Americans come down with infections caused by campylobacter, a bug transmitted through undercooked chicken or other foods contaminated with juices from raw poultry.

To treat the illness, doctors typically prescribe antibiotics called fluoroquinolones. These drugs are usually effective in knocking out the infection in a day or two, but if people are not treated, the illness can persist for up to three weeks.

A decade ago, about one in 100 people with campylobacter illness experienced antibiotic resistance; that is, the drugs didn’t work against the bug. By 1999, remarkably, antibiotics failed to work in one of six people, according to the Food and Drug Administration. The FDA says that 80% of all chickens are now contaminated with campylobacter, and one in four of those chickens carries a drug-resistant form of the bacterium. How did this happen so fast?

In 1995 the FDA allowed poultry growers to use fluoroquinolones to prevent respiratory infections in chickens. The rationale went like this: If one chicken catches pneumonia, it quickly spreads to the rest of the flock. So if low doses of the drug were added to the birds’ drinking water, it would prevent the rest of the flock from getting sick.

At the time, scientists from the federal Centers for Disease Control and Prevention argued that feeding fluoroquinolones to livestock would eventually make the drugs useless in treating campylobacter infections in humans.

Dr. David Satcher, then head of the CDC and later surgeon general, told the FDA that “the widespread use of fluoroquinolones in animals, even when limited to therapeutic use, will hasten the emergence of resistance, especially in bacteria transmitted by food.”

The poultry industry argued that the antibiotics were used sparingly, on fewer than 1.5% of growers’ flocks--still about 90 million chickens. The FDA agreed with the industry. Before long, however, the danger that Satcher warned about began to surface.

A study by the Minnesota Department of Health, published in the New England Journal of Medicine in 1999, found that 88% of the chickens purchased at grocery stores and other retail outlets were contaminated; 20% of them carried drug-resistant organisms. They also found that drug-resistant infections increased significantly in humans, from 0.8% in 1996 to 3% in 1998.

To be sure, antibiotic use in chickens and growing U.S. consumption of poultry are not the only factors contributing to antibiotic resistance in humans.

Doctors who prescribe antibiotics for patients with viral infections such as colds, for which antibiotics are ineffective, are part of the problem as well. So are parents who ask for antibiotics for their kids’ ear infections when, in some cases, the drugs are not necessary.

Here’s how chickens contribute to the problem: Like all animals, chickens carry many kinds of bacteria in their gut. Low doses of fluoroquinolones kill not only bacteria that cause pneumonia in chickens, but also some of the other germs, including campylobacter. Not all the campylobacter bugs are killed, however. Those that remain mutate and rapidly become resistant to the antibiotics.

During processing, when the birds are eviscerated and de-feathered, campylobacter can contaminate the birds’ skin. Chickens are also chilled in a communal water bath where cross-contamination occurs.

When chicken is prepared for sale, juices accumulate in the package. If those juices drip on the cutting board in your kitchen or on uncooked foods such as fruits and vegetables, you can get sick from eating them.

Fortunately, something can be done before this problem gets worse. After a scientific link was found between drug resistance in humans and fluoroquinolones fed to chickens, the FDA in 2000 withdrew approval of two drugs used to treat sick chickens: sarafloxacin (SaraFlox), made by Abbott Laboratories, and enrofloxacin (Baytril), made by Bayer.

“We don’t believe that fluoroquinolones are safe to use in poultry,” says Dr. Linda Tollefson, deputy director of the FDA’s center for veterinary medicine. “Chickens treated with fluoroquinolones are not safe to eat.”

Abbott agreed to remove sarafloxacin from the market, but Bayer is challenging the FDA action.

“We can’t find the link between the use of Baytril and poultry,” says Bayer spokesman Bob Walker. “We strongly believe in the product. Instead of being a detriment, it’s a benefit to safe food.”

Walker also contends that no other drug works on chickens with respiratory illness. But the FDA says there are other antibiotics that can be used.

The fight against fluoroquinolones has found some unexpected support from industry. The Wendy’s restaurant chain, which uses 200 million pounds of poultry a year, doesn’t buy birds that have been treated with fluoroquinolones. Neither does McDonald’s. And Foster Farms, the largest poultry producer on the West Coast, says it does not use fluoroquinolones to treat its flocks.

Foster says that if a few chickens get sick, they are removed from the flock. If many birds become ill, the flock may be treated with other animal antibiotics.

The resistance to campylobacter infections is “a harbinger of worse things to come,” says Dr. Kirk Smith, an epidemiologist with the Minnesota Department of Public Health. “Now it’s campylobacter; salmonella is probably next. It’s a nastier pathogen.”

In Europe, health officials have reported cases of antibiotic resistance in patients with salmonella infections. Children with immature immune systems and older adults whose immune systems are weakened by illness are especially susceptible to salmonella poisoning and can die from the infection.

The FDA is expected to rule on Bayer’s challenge in the next year. The outcome will have ramifications for both the public and the industry.

The decision could lead to a broad review of the use of antibiotics in all food animals, including those used to promote growth.

What can consumers do in the meantime? They could avoid eating chickens treated with fluoroquinolones. But that’s easier said than done. Most chickens sold in supermarkets don’t come with labels declaring whether they’ve been treated with the drug.

Chicken dinners in restaurants don’t carry warning labels either. When big food concerns, such as Wendy’s, decide to buy antibiotic-free chickens, they don’t always make public announcements.

If you’re lucky, you might be able to find a local grower who doesn’t feed antibiotics to his chickens.

At my local farmers market, a chicken grower posts a big sign every Saturday proclaiming his chickens as drug-free. It’s not unusual to see long lines form by his stall.

If you’re worried about antibiotics in your poultry--and there is good reason for concern until such time as the government completely bans their use--it’s a good idea to heed the experts’ advice. Wash any surface that comes in contact with chicken juices, and avoid poultry that looks the slightest bit undercooked.

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Trudy Lieberman can be reached by e-mail at trudyal530@aol.com. Health Matters appears on the third Monday of the month.