Antimicrobial Soaps Can Cause the Accumulation of Bacteria in the Human Nose

An antimicrobial agent found in common household soaps, shampoos and toothpastes can go inside the human nose where it promotes colonization by Staphylococcus aureus and may predispose individual to infection.Researchers at the University of Michigan report their findings this week in a study published in mBio ® , the online magazine and free access to the American Society for Microbiology.

Triclosan, a synthetic compound used in a range of personal care products such as antibacterial soaps, toothpaste, kitchen surfaces, clothing and medical equipment was found in the nasal passages of 41% of adults sampled A greater proportion of subjects with triclosan also had colonization by S. aureus . S. aureus may promote infection in some populations such as people undergoing surgery.

Triclosan has been around for 40 years, said the lead author of the study, Blaise Boles, assistant professor of molecular and cell biology and development at the university, and it has been incorporated into many antibacterial household products the last decade.

Other studies have found traces of triclosan in human fluids, such as serum, urine and milk, and studies in mammals showed that high concentrations of triclosan can disrupt the endocrine system and reduce cardiac function and skeletal muscle.

"  It's really common in hand soaps, toothpastes and mouthwashes, but there is no evidence, it is probably a better job than regular soap  , "says Boles. "  This agent may have unintended consequences in our bodies. It could promote the nasal colonization of S. aureus and do some people have an increased risk of infection.  "

Experiments have found that S. aureus cultured in the presence of triclosan were more capable of binding to human proteins, and that rats exposed to triclosan were more sensitive to nasal colonization by S. aureus .

"  Given the widespread use of triclosan in consumer products and widespread contamination in the environment, our data combined with previous studies showing the effects of triclosan on the endocrine system and muscle function suggest a reassessment triclosan in consumer products is urgently needed  , "the authors write.

Boles said he would conduct a more extensive investigation to determine whether triclosan affects microbial colonization in other sites in the body.

Is Antibacterial Soap Safe ?

When you're buying soaps and body washes, do you reach for the bar or bottle labeled "antibacterial"? Are you thinking that these products, in addition to keeping you clean, will reduce your risk of getting sick or passing on germs to others?

Not necessarily, according to experts at the Food and Drug Administration (FDA).

Every day, consumers use antibacterial soaps and body washes at home, work, school and in other public settings. Especially because so many consumers use them, FDA believes that there should be clearly demonstrated benefits to balance any potential risks.

In fact, there currently is no evidence that over-the-counter (OTC) antibacterial soap products are any more effective at preventing illness than washing with plain soap and water, says Colleen Rogers, Ph.D., a lead microbiologist at FDA.

Moreover, antibacterial soap products contain chemical ingredients, such as triclosan and triclocarban, which may carry unnecessary risks given that their benefits are unproven.

"New data suggest that the risks associated with long-term, daily use of antibacterial soaps may outweigh the benefits," Rogers says. There are indications that certain ingredients in these soaps may contribute to bacterial resistance to antibiotics, and may have unanticipated hormonal effects that are of concern to FDA.

In light of these data, the agency issued a proposed rule on Dec. 16, 2013 that would require manufacturers to provide more substantial data to demonstrate the safety and effectiveness of antibacterial soaps. The proposed rule covers only those consumer antibacterial soaps and body washes that are used with water. It does not apply to hand sanitizers, hand wipes or antibacterial soaps that are used in health care settings such as hospitals.

According to Rogers, the laboratory tests that have historically been used to evaluate the effectiveness of antibacterial soaps do not directly test the effect of a product on infection rates. That would change with FDA's current proposal, which would require studies that directly test the ability of an antibacterial soap to provide a clinical benefit over washing with non-antibacterial soap, Rogers says.

What Makes a Soap "Antibacterial?"

Antibacterial soaps (sometimes called antimicrobial or antiseptic soaps) contain certain chemical ingredients that plain soaps do not. These ingredients are added to many consumer products in an effort to reduce or prevent bacterial contamination.

A large number of liquid soaps labeled "antibacterial" contain triclosan, an ingredient of concern to many environmental and industry groups. Animal studies have shown that triclosan may alter the way hormones work in the body. While data showing effects in animals don't always predict effects in humans, these studies are of concern to FDA as well, and warrant further investigation to better understand how they might affect humans.

In addition, laboratory studies have raised the possibility that triclosan contributes to making bacteria resistant to antibiotics. Such resistance can have a significant impact on the effectiveness of medical treatments.

Moreover, recent data suggest that exposure to these active ingredients is higher than previously thought, raising concerns about the potential risks associated with their use regularly and over time.