Tuesday, November 06, 2012

Antibiotics: friend or foe?

Antibiotics: friend or foe?

Monday, November 05, 2012

By David Templeton, Pittsburgh Post-Gazette

When patients demand antibiotics for a cold, the flu, or any other viral infections, physicians sometimes appease them with a prescription. On other occasions, doctors prescribe antibiotics for infections most commonly caused by viruses but sometimes caused by bacteria or that progress to a bacterial infection.

Antibiotics kill germs -- bacteria -- and have no effect on viruses, making the above practices unnecessary and dangerous to health.

The overuse of antibiotics not only boosts health care costs but also causes bacterial resistance to the drugs. Examples include the growing difficulty in treating serious and sometimes fatal bacterial infections, methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile (C diff), both of which are on the rise.

Researchers also are linking health problems during childhood to early use and overuse of antibiotics.

When given in the first six months of life, antibiotics are now being suspected of leading to obesity and even type 2 diabetes, with a lifelong ripple effect on health. Antibiotics also can alter a child's immune system, although the health impacts are not yet clear.

"Antibiotic resistance is one of the world's most pressing public health threats," the U.S. Centers for Disease Control and Prevention states. More than 50 percent of antibiotics are unnecessarily prescribed in doctors' offices for upper respiratory infections including coughs and colds, most of which are caused by viruses. Half of all antibiotics used in hospitals are unnecessary or inappropriate, the CDC says.

Reactions that children have to antibiotics "are the most common cause of emergency department visits for adverse drug events," according to the CDC. Children can have as many as nine colds a year. Studies show that three of 10 children who receive outpatient health care for the common cold are prescribed unneeded antibiotics.

While those numbers have been improving in recent years, any unneeded use of antibiotics causes harm. For the past 70 years, antibiotics have been powerful tools, but their overuse is changing that. 

"Antibiotic resistance occurs when bacteria change in a way that reduces or eliminates the effectiveness of antibiotics," the CDC's "Get Smart" program states. "Infections with resistant bacteria have become more common in health care and community settings, and many bacteria have become resistant to more than one type or class of antibiotics."

It also is getting more difficult to develop new antibiotic drugs.

"The problem is that we expect antibiotics to work for every illness, but they don't," the CDC says, calling for more effective antibiotic stewardship programs.

Arjun Srinivasan, associate director of CDC's health-care-associated infection prevention programs, said the "Get Smart" programs are making progress in improving how antibiotics are used, but the problem is far from being resolved. Next week is CDC's "Get Smart" week to raise national awareness about the problem.

Recent research completed at New York University's Langone Medical Center has found that antibiotics prescribed for infants in the first six months of life can alter the baby's metabolism in ways that can lead to obesity and even type 2 diabetes, with the chance of those health impacts resonating throughout the person's life.

Studies completed under the leadership of Martin Blaser, chairman of the medical center's department of medicine, determined that early doses of antibiotics kill off the natural flora in the gut, or the good bacteria that are  not only necessary to defend against bacterial infections but also involved in metabolism.

Early doses of antibiotics intensify the metabolism, causing extraction of more calories than normal from food, leading to weight gain. Dr. Blaser said a 15-year-long epidemiological study in England found that children treated with antibiotics in the first months of life had a 22 percent higher rate of obesity than those who didn't receive antibiotics during that time period. The findings, he said, may help explain the rise in type 2 diabetes in children.

A mouse study, done earlier by the team, reached similar conclusions about antibiotics altering the metabolism and immune system, he said. But evidence long has existed that antibiotics cause weight gain.

"One of the things that pointed me in this direction was the knowledge over the last 60 years that farmers were giving low doses of antibiotics to livestock to fatten them up," Dr. Blaser said. "Antibiotics are growth promoters, and they established the principles that antibiotics early in life affect early development."

The research also documented changes induced by antibiotics in different T-cell populations in the immune system.

"We are changing the composition of the natural flora and the change in composition is happening at a critical time in the child's development," Dr. Blaser said. "What happens in early life sets the stage for overall development for the rest of the person's life."

He's now working to identify how changes in the natural flora, or "microbiota," cause changes to metabolism and the immune system with hope of developing a probiotic treatment to restore the natural flora to counter or reduce the health impacts of antibiotics.

Dr. Srinivasan praised Dr. Blaser's research that identifies other health concerns linked to the use of antibiotics. But the focus is on bacterial resistance.

"Certainly the situation with antibiotic resistance is getting worse," he said. "Bacteria are developing resistance to more antibiotics, making it more difficult to treat patients or to find the right treatments for the right patients."
The overuse of antibiotics isn't limited by age group.

A University of Pittsburgh-based research team, using Medicare Part D data from 2007 to 2009, found that one in five people 65 and older are taking at last one course of antibiotic during any three-month season of the year, with 47 percent taking at least one dose of antibiotics sometime during the year.

The study was published Sept. 24 online in the Journal of the American Medical Association's Archives of Internal Medicine.

Doctors who treat older adults in Southern states prescribe antibiotics more often than any other region in the United States, the study says. On average, 21.4 percent of older adults in the South are taking antibiotics during any three-month period of the year. Western states have the lowest seasonal rate of 17.4 percent, with the Northeast at 18.2 percent and the Midwest at 19.2 percent. The usage rate is highest January through March, and lowest from July through September.

The study found variations in antibiotic use across the regions, even after researchers adjusted for differences in population, suggesting that physicians and health care systems differ region to region in how antibiotics are prescribed.

Oregon and Wyoming had the lowest rate of antibiotic use among seniors, while Alabama and Mississippi had the highest. Pennsylvania ranked 23rd with 46 percent of older adults taking a course of antibiotics at least once during the year.

"Some conditions require antibiotics and some don't justify the use of antibiotics," said Yuting Zhang, the study author and assistant professor at Pitt's department of health policy and management. "Some regions do really well. What can we learn from them? What programs are they using? Can programs they are using in the West be adapted to the South?"