Davida S. Smyth, PhD | November 19, 2014
Last month’s article by Bill Walsh, “The Dirt on Antimicrobials”, spoke of the recent trend to infuse antimicrobial substances other than antibiotics into building products. I had known that antimicrobial substances were creeping into many consumer items, such as soap, toothpaste, mouthwash, and hand-wipes to name but a few. I did not, however, know the extent to which these substances were finding their way into people’s homes, places of work, offices, hospitals and other environments via “paints, tiles and grouts, carpets, solid surfaces, faucets, elevator buttons and toilet seats.” The lack of study and evidence to support their use in these situations, combined with what we know of bacteria’s capacity to adapt, is extremely worrisome for me -- as a microbiologist and a consumer. In this situation I believe it’s a case of what we don’t know might hurt us!
This trend is likely a consequence of people’s fears when it comes to bacteria. You say bacteria and people think plague, pestilence, and pneumonia. I think yogurt, immunity, and insulin production.
As a teacher of microbiology at an inner city university, it is often a struggle to help students understand just how important bacteria are. Bacteria are necessary to produce yogurt, beer, bread, and other tasty treats. They are used in manufacturing of pharmaceuticals and biofuels. They fix nitrogen in our soils making life as we know it possible, and are an essential part of our digestive systems. The bacteria in our microbiome also protect us from harmful pathogens in the environment, and even contribute to our healthy mental development. Bacteria are ubiquitous and an essential part of our environment and ecology. These are the good bacteria you might say.
The bad bacteria could be described as those who have taken advantage of the greatest skill bacteria have; their capacity to adapt, by mutating, by acquiring new genes from other bacteria and even by integrating viral DNA into their own genomes. The ability of bacteria to cause damage to our bodies and make us ill is a consequence of what we call bacterial virulence or pathogenicity, often acquired, and the result of the evolution of these highly resilient organisms.
The downright ugly bacteria are truly frightening. The emergence of highly antibiotic resistant bacteria in recent times has led to fear among microbiologists, infectious disease specialists, epidemiologists, and health care practitioners. This fear comes from a realization that we are on the brink of a new age, where the wonder drugs that prevented greater illness and death in the past are no longer effective. For microbiologists, who study these types of organisms, this is no surprise, since research into new antibiotics has slowed greatly, and the overuse and misuse of antibiotics in agriculture and medicine has long been noted.
As HBN pointed out, the ugly truth is that antimicrobial substances that are being added to building materials may not offer protection from ugly bacteria, and may cause harm, both to the environment and us. The FDA and EPA are currently collaborating with researchers to establish if the endocrine-related effects of triclosan, including toxicological effects and the doses at which they occur, are safe or not. In addition, the FDA does not have evidence that triclosan in antibacterial soaps and body washes provides any benefit over washing with regular soap and water. The Mayo Clinic web site indicates that cutting boards impregnated with triclosan are ineffective: “There's no evidence that cutting boards containing triclosan, an antibacterial agent, prevent the spread of food-borne infections. These boards also may give a false sense of security and cause you to relax other efforts to keep the board clean. In addition, triclosan-treated boards don't kill germs. Antibacterial compounds only slow reproduction of microorganisms. Germs will die, but slowly enough to still contaminate other food or hands that come into contact with the board.” Several groups have noted the endocrine disrupting capacity of triclosan, it’s ability to cause damage to marine ecosystems and the even more worrying finding, that the chemical itself can be isolated from human tissue and fluids. Shockingly, a recent study published in MBio by has found that triclosan actually promotes nasal colonization by Staphylococcus aureus, and even more alarmingly, it is often the isolate from a patient’s nose that goes on to cause infection in the individual.
At my university, the students and I are working to identify what constitutes a healthy building. Just like within us and on us, bacteria are an expected component of our building’s ecology, and transient pathogenic organisms are likely to be found colonizing surfaces. Through studying the seasonal dynamics and mechanisms by which bacteria colonize our building, we will have a greater understanding of how the building contributes to the bacteria found. We focus on Staphylococci, and have found multiple species of this bacteria on elevator buttons. The plates shown here are HardyCHROM™ MRSA agar plates, which select for resistant Staphylococci. Multiple colonies of presumptive Staphylococci can be seen. Several groups have noted that certain Staphylococci show resistance to triclosan, emphasizing that impregnating these buttons with this chemical could likely result in the selection of resistant bacteria.
It is only through such a study, that we could make an informed decision as to how to best clean and sanitize and prevent transmission of pathogens, rather than a blunt force removal of the potentially healthy organisms that could perhaps protect us from pathogens.
As a teacher, I will continue to educate my students as best I can and encourage them to make informed choices about hand hygiene. Soap and water is just as good in the home. When it comes to building products, we should conduct the necessary studies to know if we are doing more harm than good before adding antimicrobials as a ubiquitous presence in our homes, schools and offices. It is better to know what we are exposing ourselves to, so that in years to come, we do not have an even greater threat to our health and environment than antibiotic resistant bacteria, organisms that are pan resistant to all that we have, because that would be downright ugly.
 Calafat AM, Ye X, Wong LY, Reidy JA, Needham LL. Urinary concentrations of triclosan in the U.S. population: 2003-2004. Environ Health Perspect 2008;116(3):303-307.
 Geens T, Neels H, Covaci A. Distribution of bisphenol-A, triclosan and n-nonylphenol in human adipose tissue, liver and brain. Chemosphere. 2012 May;87(7):796-802.
 Wolff MS, Teitelbaum SL, Windham G, Pinney SM, Britton JA, Chelimo C, et al. Pilot study of urinary biomarkers of phytoestrogens, phthalates, and phenols in girls. Environ Health Perspect 2007;115:116-121.
 Syed AK, Ghosh S, Love NG, Boles BR. Triclosan promotes Staphylococcus aureus nasal colonization. MBio. 2014 Apr 8;5(2):e01015.
 Schmid MB, Kaplan N. Reduced triclosan susceptibility in methicillin-resistant Staphylococcus epidermidis. Antimicrob Agents Chemother. 2004 Apr;48(4):1397-9.
Acknowledgments: Dr Smyth’s team is composed of undergraduate Emerging Scholars in the Biomedical Informatics Program at New York City College of Technology, Manhin Lam, Fabiola Fontaine and Wing Pan Kenny Tsang. Funding for this work was provided by a PSC-CUNY award to Dr Smyth.