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Antibacterial soaps are all the rage, but humble soap and water will clean just as well

Tuesday, November 05, 2002

By Anita Srikameswaran, Post-Gazette Staff Writer

It's time for antibacterial soaps to come clean.

First introduced for general consumers in the 1990s, products containing and promoting antibacterial ingredients have multiplied like germs on grocery store shelves and bath boutiques.

Under a black light, hands rubbed with a lotion to make them glow show the clean, left, and the dirty. (Darrell Sapp, Post-Gazette)

But a recent, yearlong Columbia University study shows soaps laced with microbe-killing chemicals are no better at making hands germ-free than plain soap.

The findings have drawn attention to the concerns some experts have raised about whether the long-term, everyday use of antibacterial soaps could produce organisms that are resistant to antibiotics.

Are these widely available soaps appropriate for routine use in healthy households or should they be reserved for medical settings to prevent the most vulnerable patients from contracting infections?

In the Columbia study, researchers led by Elaine Larson, associate dean for research at the university's nursing school, followed more than 200 New York City households for a year. Half were randomly chosen to use antibacterial soap while the other half used plain soap. The soaps were liquid over-the-counter varieties that looked the same, and neither the researchers nor the participants knew what kind each family was using until the study was over.

Bacteria were cultured from the primary homemaker's hands after one hand-washing at the beginning of the study and every three months until a year had passed. At each testing, both groups had equivalent reductions in the numbers of germs on their hands.

At first, anywhere from 800,000 to 1 million bacteria were found on the participants' hands, which Larson called a normal number. A year later, half as many bacteria were present, regardless of what soap was used. The homemakers were not told how often or how long to wash their hands, and there were no noteworthy differences between the groups in dishwasher or washing machine use, number of children and other factors.

Larson, whom other infection control experts call the "hand-washing queen," suspected that study participation encouraged people to wash their hands more frequently, especially since they got the soap for free. She noted that there was no difference in bacterial counts among people who described themselves as frequent hand-washers and those who didn't.

"So probably everybody washed their hands more," Larson said. "That's why they had cleaner hands after a year."

She pointed out that the study looked only at bacterial counts, not at infection rate. Other studies have shown that regular hand-washing reduces the chances of getting sick. And, the antibacterial soaps available to average consumers contain relatively low concentrations of antimicrobial agents, such as triclosan.

"Certainly in hospitals we use different antiseptics that have a higher strength," Larson explained. So "this study should not be in any way related to the hospital."

Officials from the trade groups Soap and Detergent Association and the Cosmetic, Toiletry and Fragrance Association, issued a statement cautioning people not to draw broad conclusions from the research.

"The study apparently evaluated overall skin bacteria, and did not examine the differences in effectiveness of an antibacterial product compared to plain soap on transient, or acquired, bacteria," they said. "Antibacterial hand soaps, when properly used, are effective at reducing the risk of infection by killing or controlling the growth of harmful transient microorganisms on the skin, as evidenced in their broad use in healthcare."

The resistance worry

But some experts are concerned that everyday use of antibacterial soaps in healthy households could give rise to disease-causing organisms that are resistant to antibiotics.

Clara Davis, a Ph.D. student at Stanford University, presented research last month at a San Diego meeting of the American Society for Microbiology showing that some strains of E. coli bacteria developed resistance to triclosan and became increasingly tolerant of it with constant exposure to the chemical.

The presence of an antimicrobial could change the numbers of various kinds of bacteria in an environment, with susceptible organisms being killed off, allowing resistant ones to survive and even thrive. Some might be bacteria that can cause disease because of their increased numbers, once held in check by other species, Davis explained.

As she put it, "maybe we're changing the [bacterial] community around us."

Some of the resistant E. coli strains in her experiment grew better in the presence of triclosan.

"There's no reason to assume they wouldn't take over a population," Davis said. "So potentially the soap could become useless" against some bacterial species.

Davis herself avoids using soaps that contain antimicrobials because of such concerns.

"Soap by itself works great," she said. "What adding triclosan to the soap probably does is it washes dead bugs down the drain instead of live bugs."

Dr. Stuart Levy, director of the Center for Adaptation Genetics and Drug Resistance at Boston's Tufts University and author of "The Antibiotic Paradox," (Perseus, 2002) was one of the first researchers to find a bacterial gene mutation that conferred triclosan resistance. He insists on washing up before meals and doesn't use antibacterial soaps at home.

"The home is a healthy place," he said. "You just want to remove the major part of the organisms from your hands. You want to remove them. You don't need to kill them."

Levy and Larson are working on a follow-up study in which the bacteria cultured from the New York homemakers' hands will be identified and tested for resistance, both to triclosan and to clinically used antibiotics. Larson noted that no human study has found that resistance to the soap ingredient led to resistance to other antibiotics.

The perils of overkill

Levy discusses the hygiene hypothesis, the idea that children who are too clean are at greater risk for immune system-related diseases, such as asthma, later in life.

"It concerns me that it's only going to be magnified if we add to this zealous cleanliness," he said.

Levy doesn't think regular use of antibacterial soap means a greater personal risk of developing hard-to-treat infections.

"It's just a question of bringing reality to mystique," he said. "They should be reserved for the hospital where they are protecting people who are really vulnerable. We shouldn't be wasting them in healthy households."

Antimicrobial soaps have been shown to reduce transmission of infectious agents between patients in hospitals. But as Levy pointed out, health professionals are expected to scrub their hands for several minutes, rather than simply rinse their fingers under running water for a few seconds.

Still, about 2 million patients annually get an infection while in the hospital, according to the U.S. Centers for Disease Control and Prevention.

Part of Adrianne Farley's job as an infection control nurse at Children's Hospital is to educate families and staff about the importance of washing up. Everyone says they follow the recommendations and then they promptly pass the buck to everyone else.

"You talk to doctors, it's always nurses. You talk to nurses, it's always doctors," Farley joked. "You put doctors and nurses in a room, it's always respiratory therapists."

Farley has used antibacterial soaps routinely for years. Her daughter, now 25, so well practiced what she was taught about handwashing that when she did a childhood science project on the topic, she couldn't get bacteria from her hands to culture.

"The bottom line comes down to just get in there and wash your hands," Farley said. "Anything that can get people near a sink is a good thing."

And although the soaps are usually advertised as antibacterial, the most common infections, such as colds and flus, are caused by viruses. Regular handwashing with either plain or antibacterial soap can rinse those germs away. Farley also suggests coughing or sneezing into the crook of the elbow, a la Dracula, rather than the hand, which would have to be washed right away to prevent depositing germs on surfaces through a touch.

She added that inappropriate use of antibiotics to treat viral infections, the use of antibiotics in livestock and other factors contribute far more to resistance than does antimicrobial soap.

"That's absolutely correct and I'd be the first to say it," Levy said. "Handwashing with these [soaps] is not the reason for the major antibiotic resistance problem now. But, if there's no benefit and this can add even a little bit to the major problem of resistance, why do we need it?"