Antimicrobial from soaps promotes bacteria buildup in human noses
An antimicrobial agent found in common household soaps, shampoos and toothpastes may be finding its way inside human noses where it promotes the colonization of Staphylococcus aureus bacteria and could predispose some people to infection. Researchers at the University of Michigan report their findings this week in a study published in mBio, the online open-access journal of the American Society for Microbiology.
Triclosan, a man-made compound used in a range of antibacterial personal care products such as soaps, toothpastes, kitchen surfaces, clothes and medical equipment, was found in nasal passages of 41% of adults sampled. A higher proportion of subjects with triclosan also had S. aureus colonization. S. aureus could promote infection in some populations such as people undergoing surgery.
Triclosan has been around for the past 40 years, says senior study author Blaise Boles, PhD, an assistant professor of molecular, cellular and developmental biology at the university, and has been incorporated into many antibacterial household products within the past decade. Other studies have found traces of triclosan in human fluids including serum, urine and milk, and studies in mammals have found that high concentrations of triclosan can disrupt the endocrine system and decrease heart and skeletal muscle function.
"It's really common in hand soaps, toothpastes and mouthwashes but there's no evidence it does a better job than regular soap," Boles says. "This agent may have unintended consequences in our bodies. It could promote S. aureus nasal colonization, putting some people at increased risk for infection."
Additional experiments found that S. aureus grown in the presence of triclosan was better able to attach to human proteins, and that rats exposed to triclosan were more susceptible to S. aureus nasal colonization.
"In light of the significant use of triclosan in consumer products and its widespread environmental contamination, our data combined with previous studies showing impacts of triclosan on the endocrine system and muscle function suggest that a reevaluation of triclosan in consumer products is urgently needed," the authors wrote.
Boles says he would like to conduct a more broad survey to determine if triclosan is influencing microbial colonization at additional human body sites.
Explore further: FDA calls for safety review of antibacterial soaps (Update 2)
Journal reference: mBio
Triclosan Promotes Staphylococcus aureus Nasal Colonization
Adnan K. Syeda, Sudeshna Ghoshb*, Nancy G. Loveb, Blaise R. Bolesa
+ Author Affiliations
aDepartment of Molecular Cellular and Developmental Biology, University of Michigan, Ann Arbor, Michigan, USA
bDepartment of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan, USA
+ Author Notes
?* Present address: Sudeshna Ghosh, Biotechnology Institute, University of Minnesota, St. Paul, Minnesota, USA.
Address correspondence to Blaise R. Boles, brboles@umich.edu.
A.K.S. and S.G. contributed equally to this article.
Invited Editor Eric Skaar, Vanderbilt University Editor Scott Hultgren, Washington University School of Medicine
ABSTRACT
The biocide triclosan is used in many personal care products, including toothpastes, soaps, clothing, and medical equipment. Consequently, it is present as a contaminant in the environment and has been detected in some human fluids, including serum, urine, and milk. Staphylococcus aureus is an opportunistic pathogen that colonizes the noses and throats of approximately 30% of the population. Colonization with S. aureus is known to be a risk factor for several types of infection. Here we demonstrate that triclosan is commonly found in the nasal secretions of healthy adults and the presence of triclosan trends positively with nasal colonization by S. aureus. We demonstrate that triclosan can promote the binding of S. aureus to host proteins such as collagen, fibronectin, and keratin, as well as inanimate surfaces such as plastic and glass. Lastly, triclosan-exposed rats are more susceptible to nasal colonization with S. aureus. These data reveal a novel factor that influences the ability of S. aureus to bind surfaces and alters S. aureus nasal colonization.
IMPORTANCE Triclosan has been used as a biocide for over 40 years, but the broader effects that it has on the human microbiome have not been investigated. We demonstrate that triclosan is present in nasal secretions of a large portion of a test population and its presence correlates with Staphylococcus aureus nasal colonization. Triclosan also promotes the binding of S. aureus to human proteins and increases the susceptibility of rats to nasal colonization by S. aureus. These findings are significant because S. aureus colonization is a known risk factor for the development of several types of infections. Our data demonstrate the unintended consequences of unregulated triclosan use and contribute to the growing body of research demonstrating inadvertent effects of triclosan on the environment and human health.
FOOTNOTES
Citation Syed AK, Ghosh S, Love NG, Boles BR. 2014. Triclosan promotes Staphylococcus aureus nasal colonization. mBio 5(2):e01015-13. doi:10.1128/mBio.01015-13.