Tuesday, August 16, 2011

Why some diseases are resistance to antibiotic

"Here's the big secret that no one wants to talk about: We're not very good at keeping what's inside a cow's intestines out of the meat."

The roomful of young doctors at Oakland Children's Hospital chuckled as retired cardiologist Jeff Ritterman whispered audibly, his hand hiding his mouth. He went on to explain in less dramatic fashion how the widespread use of antibiotics to treat sick livestock, prevent the spread of disease in cramped conditions or simply promote animal growth has fueled the proliferation of antibiotic-resistant bacteria that is now making many infections in humans harder to treat.

Some human infections now resist multiple antibiotics; the pathogens include methicillin-resistant Staphylococcus aureus (MRSA), a pathogen responsible for taking more lives each year than AIDS.

Earlier this month, stores and consumers across the country discarded 36 million pounds of ground turkey in the second-largest recall in U.S. history. More than 100 people became sick from the salmonella-tainted meat; at least one person died.

The firms feeding animals antibiotics question direct links to such outbreaks, but these kinds of tragedies come as little surprise to the medical community, which has long been confronted with the consequences of antibiotic resistance. "Everyone has seen cases of MRSA. Every doctor is schooled in how many seconds to wash their hands, and nurses are told to get rid of their nails," Ritterman, now a city councilmember in Richmond, Calif., told The Huffington Post. "It's a helpless feeling when your patient dies of an infection that you can't cure."

More than 75 years after antibiotics first debuted as the miracle cure, treating an infection today often requires greater doses, a second drug or even riskier options.

"Antibiotics are probably as big of an advance in medicine as there has ever been," Ritterman said. "We are undoing our greatest achievement."

Eating contaminated meat is not the only route to an antibiotic-resistant infection. Contact with animals, meat or milk -- and even exposure to bacteria via the air or water -- can pose a public health threat. Of course, blame has also long been directed at the widespread use of antibiotics within medicine.

Doctors have begun limiting the antibiotic prescriptions they write, aware that misuse or overuse of the drugs enables antibiotic-resistant bacteria to proliferate faster than their antibiotic-susceptible counterparts. In other words, what doesn't kill them makes them stronger -- potentially turning them into "superbugs" that can outsmart medicine's current range of weaponry.

But while most doctors are familiar with the growing threat of antibiotic resistance, fewer are aware of the shared responsibility of agribusiness.

"That part of the antibiotic resistance story is largely hidden for docs," said Ritterman, adding that he was shocked upon first hearing that 80 percent of the nation's antibiotics go to livestock.

Doctors are learning, though, thanks partly to programs like the one at which Ritterman spoke, as well as a growing number of environmental health workshops and online modules. More clinicians now know, for example, that antibiotics approved by the U.S. Food and Drug Administration for growth promotion in the early 1950s remain a huge part of the nation's livestock industry even though the government acknowledged the attendant health risks to humans more than 30 years ago.

According to the FDA, about 90 percent of the antibiotics consumed by livestock are given to them via animal feed or water. Critics suggest that most of these drugs are used at low doses to bulk up the animals, speeding them to market. Exposure to antibiotics at levels insufficient to kill the bacteria are more likely to result in antibiotic resistance.

Many in the food-animal production business beg to differ. Richard Carnevale, vice president for regulatory, scientific and international affairs at the Animal Health Institute, which represents pharmaceutical companies, argued that using the drug in the feed doesn't necessarily mean that it is being used "sub-therapeutically".

"We don't really think that the antibiotics given to animals in feed are big contributors to the problems in human medicine," Carnevale said. Nearly half of the antibiotics used in agriculture, he said, are not even part of human medicine's antibacterial arsenal.

"Antibiotics are used to keep animals as healthy as possible, and healthy animals are at the base of a safe food system," said Carnevale. He added that U.S. producers are "always looking for ways to change the way they do things to improve animal health," but that removing antibiotics would "increase production costs."

While the battle wages in the United States, other countries including the entire European Union have banned the use of antibiotics for livestock growth promotion. The industry appears to be holding up just fine as resistance rates drop, according to recent Danish studies. Further, a U.S. study published last week in Environmental Health Perspectives found that going organic and stopping the use of antibiotics resulted in quick and significant reductions in antibiotic resistance.

Lucia Sayre, co-executive director at the San Francisco Bay Area chapter of the advocacy group Physicians for Social Responsibility, says tapping the power and respect of the medical community can provide the necessary boost to change the food industry.

"Nobody believes anyone more than their docs and nurses," Sayre said, citing a recent Gallup Poll that found 70 percent of people trusted their doctor's advice without a second opinion. "We're trying to max their voice."

And when physicians and nurses realize that efforts in the doctor's office are not enough, she added, many -- like Ritterman, the retired cardiologist -- are eager to be vocal, whether educating patients and fellow doctors or advocating for regulatory reforms.

"A doctor may be able to help individuals in their office, but changes in policy can lift the health of an entire population. We need to really advance American medicine to the policy stage," Ritterman said. "Doctors are trained to see the world through a health lens. Politicians, businessmen and economists are not."

Entire hospitals are also in on the effort. Many have adopted the concept of "Meatless Mondays" -- using the money they save on Monday to buy grass-fed meat for Tuesday, for example. Many offer a variety of alternative sources of protein such as tofu and lentils. Fletcher Allen Health Care in Burlington, Vt., serves an estimated 2 million meals a year to patients, visitors and employees. Among other healthy improvements to their menu, they have been phasing out foods produced with non-therapeutic antibiotics antibiotics. Today, about 90 percent of their beef meets this goal.

"I kept seeing more and more cases of antibiotic resistance at the hospital. It doesn't make sense to keep doing it the way we're doing it, not to mention that cases of resistance are costly," said Diane Imrie, director of nutrition services at Fletcher Allen. A study published in the journal Clinical Infectious Diseases in 2009 found that antibiotic-resistant infections cost U.S. hospitals more than $20 billion annually.

Food and beverages mean big business in the health care sector, totaling about $14 billion a year. "Through a combination of clinicians talking to patients about personal choices and getting institutional purchasers like hospitals on board, I believe we can really change the food system," said Sayre, who helps coordinate a healthy-food campaign that includes nearly 350 hospitals, including Fletcher Allen.

Sayre has also helped coordinate physicians in their push for new federal environmental health legislation. More than 1,000 signatures have been collected for the Preservation of Antibiotics for Medical Treatment Act, introduced in March after getting buried in Congress in 2007 and 2009. Another 378 groups have now endorsed the bill, including the American Medical Association and the American Academy of Pediatrics.

"Antibiotics are one of the most useful and important medical advances in recent history. Their effectiveness, however, is being compromised by bacterial resistance, arising in part from excessive use of antibiotics in animal agriculture," wrote Michael D. Maves, executive vice president of the association, in a letter of support for the legislation.

Meanwhile, the FDA has issued a draft of "Guidance on the Judicious Use of Medically Important Antimicrobial Drugs in Food Producing Animals." The agency is currently reviewing comments and determining next steps, according to FDA spokeswoman Stephanie Yao, who said that while there is no estimated timeframe for implementing final recommendations, the agency is making it a priority.

The Centers for Disease Control and Prevention also puts the issue "among its top concerns." And in June, a U.S. Department of Agriculture contractor reviewed the science and concluded that there is a strong link between rising cases of resistant infections and antibiotic use on factory farms. But as Mother Jones reported at the end of July, the "blunt" report disappeared shortly after it was posted on the Internet. (The Union of Concerned Scientists managed to recover a cached link.)

A USDA spokesman said that the document had been "removed because it was published without the review required by USDA departmental regulations to ensure objectivity, accuracy, reliability and an unbiased presentation." Yet Mother Jones pointed to an earlier Dow Jones story that quoted a USDA spokesperson saying that the more than 60 studies compiled in the report were all from "reputed, scientific, peer-reviewed and scholarly journals."


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