Blame it on the Alcohol: How Hand Sanitizer Overuse May Create a Superbug
Published in Washington University in St. Louis’s Review of Health, Frontiers Magazine.
How many times today have you used hand sanitizer?
In the midst of a pandemic — where reminders to wear a mask are more common than welcome mats, and Purell dispensers are located at every door — using antimicrobials has become second nature. The average WashU student comes into contact with hand sanitizer dozens of times a day, be it before entering a classroom, grabbing a meal at BD, walking by a Student Health Ambassador or using their own pocket sanitizer. No one thinks to count how many times they’ve washed their hands — at least, not while the health of their university depends on it. In truth, as every day brings conflicting political messages on how to handle the pandemic and unanticipated scientific findings on the virus itself, students feel helpless, and sanitizer stands as one of the few aspects of this pandemic they can control. But even though it keeps us safe in the present moment, is excessive sanitizer usage truly in our future’s best interest? Or are we setting ourselves up for an even worse public health crisis in the long term?
Popularized in the early 1990s for their ease of use, alcohol-based hand sanitizer became a staple in most healthcare settings and played a significant role in decreasing staph infections [1]. At the same time, however, hospitals saw a significant increase in resistant strains of certain pathogens, ranging from MRSA to enterococci [2]. Over the last decade, dozens of studies were published warning healthcare officials against the effects of hand sanitizer on the development of resistance in dangerous pathogens. Most recently, a 2018 Australian study comparing enterococci isolates between 1997 and 2015 found that “isolates after 2010 were 10-fold more tolerant to killing by alcohol than were older isolates.” Additionally, due to the popularity of homemade hand sanitizer over the summer, toxicologist Winston Morgan worries that alcohol substitutes known to cause gene damage like phenols and hydrogen peroxide may encourage the acquisition of resistance through mutation [3]. Thus, it’s become increasingly clear that excessive use of hand sanitizer can cause resistance — but how?
Commercial hand sanitizers claim that they kill 99.9 percent of all microbes on one’s hands, and though 0.1 percent left alive seems miniscule at face value, this percentage becomes much more significant when you take into account that the average hand holds about 3,200 bacteria from 150 different species. Those few bacteria that survive have resistance that is either intrinsic, meaning their genome initially contained a resistant gene due to inheritance or mutation during reproduction, or acquired, meaning they gained resistance by transferring genes with other bacteria [4]. When we kill off all weak bacteria on our hands, we leave behind the strong ones and allow them to reproduce, producing a colony of bacteria with a much higher frequency of resistant genes than before. This microcosmic form of natural selection is responsible for 2.8 million resistant infections and 35,000 deaths a year — and though it has currently taken a backseat to the pandemic, antimicrobial resistance has widely been considered one of the biggest public health crises around the globe since the early 2000s.
Unfortunately, these bacteria are not just becoming resistant to alcohols and disinfectants; they’re applying this resistance to antibiotics as well. A 1999 study of a common hospital disinfectant, benzalkonium chloride, found that strains of MRSA resistant to this disinfectant were also more likely to resist the very antibiotics commonly used to treat them [5]. This is because many of the mechanisms whereby alcohols kill bacteria or viruses, such as membrane damage and protein denaturation, are similar to the mechanisms antibiotics utilize to target infections [6]. Though little data is available linking alcohol resistance to antibiotic resistance, the implications of this possibility are grave — especially as our healthcare system still struggles under the weight of COVID-19.
“The prioritized allocation of isolation rooms to COVID-19 patients, management in open bays of patients colonized with [resistant bacteria]…and the inevitable higher workload of healthcare workers” are all factors identified in a “Journal of Antimicrobial Chemotherapy” article as consequences of the pandemic that will greatly exacerbate the spread of resistant bacteria [2]. Moreover, a recent report by the International Severe Acute Respiratory and Emerging Infections Consortium found that 62 percent of patients with COVID-19 had received broad spectrum antibiotics as part of their treatment despite few reports of a coinciding bacterial infection necessitating antibiotics. From over prescribed antibiotics to overwhelmed hospital beds and laboratories, crucial aspects of American healthcare have been brought to their knees by the pandemic. Adding salt to the wound with an outbreak of resistant pathogens would prove outright disastrous for any chance at a ‘return to normal.’
As sparse as the data is regarding antimicrobial resistance in the pandemic, one truth is abundantly clear: a pump of hand sanitizer is much more than it seems at first glance. Rubbing sanitizer into their palms may have become muscle memory for the average WashU student, but the student body needs to understand the detriment that antimicrobials pose to their long-term health. That’s not to say students shouldn’t be using sanitizer — hand sanitizer is proven to inactivate novel coronaviruses — but using Purell a dozen times a day means this pandemic will not end with the elimination of SARS-CoV-2 [7]. Rather, we may jump out of the frying pan and into the fire of antimicrobial resistance.
