Antimicrobial products have a ubiquitous presence in American life. Chlorox wipes are available for your cart when you enter the grocery store. Tiny bottles of Purell are attached to key chains and tucked inside backpacks and purses, held tightly as talismans against the scourges of disease and illness. However, for years infectious disease experts have been warning that antimicrobial soaps have only served to exacerbate antibiotic resistance without inferring individual benefit. This week the FDA announced a plan to phase out the use of 19 antimicrobial chemicals in soaps. This ruling represents a move towards improved antibiotic stewardship, and also reflects a more nuanced understanding about the role of bacteria in health and disease.
The adoption of the “Germ Theory” of disease was a major turning point in the development of medicine. Prior to advances in microbiology and epidemiology, a theory of “miasmas” predominated—the idea that disease was spread by a poisonous vapor or mist. A greater understanding of the causality of microbes in disease lead to great advances in care. For example, Ignaz Semmelweis, a Hungarian Obstetrician in the mid-1800s, realized that a great number of women were catching infections during childbirth after being examined by doctors who had just come from autopsy—without stopping to first wash hands. The use of antiseptic handwashing reduced maternal mortality significantly.
In the 1870s, Joseph Lister introduced the practice of using carbolic acid to sterilize surgical instruments and wounds, greatly reducing post-surgical morbidity and mortality. As any student who has scrubbed into an operation can attest, a commitment to sterility and aseptic technique is a critical component of modern surgery. The subsequent development antibiotic medications allowed for the treatment of previously invariably fatal diseases. The consensus seemed clear: microbes brought disease, and thus killing them became a matter of sanitation and health.
However, our keychain bottles of Purell are a far cry from the Hungarian obstetrics wards and Scottish surgical theaters of the 1800s. Our understanding of microbes and our relation to them are shifting.
The advent of PCR and other DNA technologies allowed us to more thoroughly explore the flora of our gut. These studies have revealed a vast complexity that we could not have imagined before when merely looking at growth under a microscope. A multifaceted ecosystem of microbes lives and functions within our gut, largely in peace and largely for our benefit. Cutting edge research is exploring the role of this diverse cacophony of species on everything from mental health to obesity.
Health, it seems, is not achieved via that eradication of microbes, but by the selective cultivation of a mixture of beneficial strains. Bacteria in the gut are responsible for producing vitamin K—a critical component for clotting. Babies receive a vitamin K shot at birth because their gut has not yet accumulated these helpful peers and thus are at increased risk of bleeding. Similarly, one of the most dreaded and serious complications of antibiotic treatment is c. difficile colitis (inflammation and infection of the colon). This disease is not caused by an organism that is inherently dangerous, but by the disruption of balance between bacterium. C. difficile typically lives peacefully within the guts of humans. It is only when other organisms have been preferentially killed that a roaring overgrowth of c.difficile is possible, leading to disease.
It also appears that our obsession with irradiating microbes and fixation on cleanliness is altering the way children’s developing immune systems interact with the environment. When compared to their peers living a more typical American childhood, Amish children were significantly less likely to suffer from allergies or asthma. Similarly, children raised in homes where dishes are hand washed have fewer allergies. It seems that exposure to sufficient quantities of bacteria is an important component of proper immune system development.
Our fondness for killing bacteria and the laxity in which we employ antimicrobial agents has lead, through evolutionary selection, to bacteria that are ever more resistant to our antibiotic medications. Increasingly frequent case reports detail microbes resistant to the most powerful antibacterial agents. Of course, it is not just germaphobes and their devotion to Lysol that are to blame—doctors frequently prescribe antibiotics inappropriately, and the meat industry uses 15-17 million pounds of antibiotics a year for the promotion of growth. However, the unnecessary use of antimicrobials in everyday products, such as soap, exacerbates this problem.
Like many facets of medicine, deeper understanding has led to a more confusing and nuanced picture of our microbial neighbors. Bacteria are still the cause of many serious and terrible infections. There are, in fact, dangerous and deadly bacteria. But, what is certain is that for the average person with a functional immune system, the use of antimicrobial soaps is entirely superfluous. The use of antimicrobial agents in soaps only exacerbates the rise of resistant organisms; the added benefit of antimicrobial agents is psychological and not biological. The FDA’s action represents a good first step in improved antibiotic stewardship and hopefully signals a societal shift in the relationship between humans and microbes.
Lauren Groskaufmanis is a graduate student in the school of medicine. Her column, “The Picture of Health,” runs on alternate Fridays.
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