What this means and why it might be happening
Though the mere presence of triclosan and these heartier germs in the same place doesn’t absolutely prove that triclosan in dust caused the antibiotic resistance to develop in the places where these microbes were found, Hartmann said the association is highly suspicious.
…just because we stopped using it in one context (hand soap), doesn’t mean that it is just going to disappear from the environment.
That’s because they discovered a relationship between the amount of triclosan and the number of antibiotic-resistant microbes in gym dust. The 11 athletic facilities with most antibiotic-resistant microbes had dust samples with triclosan at levels three times higher than all other buildings on average.
Hartmann said if there is a causal relationship between triclosan in dust and the development of antibiotic resistance, it suggests that microbes in the wild behave differently than those raised in petri dishes in the lab, which is basically where “everything we know about antibiotic resistance genes” has been discovered, Hartmann said.
These earlier lab-based studies may have found that a gene grants resistance to an antibiotic medicine, when in the wild, the gene’s actions are broader and can have multiple functions — like also providing protection against a substance like triclosan. So, when germs in the wild get exposed to triclosan, that means it’s possible that they can develop resistance to it and to a medicine at the same time.
Another theory revolves around the fact that antibiotic-resistant genes are mobile — meaning they can be traded between individual microbes like baseball cards. “It could be that there’s a gene that helps resist triclosan, but trading this gene sends along neighboring genes that confer resistance to other antibiotics.”
You should be worried but shouldn’t burn your exercise mats…yet
Don’t toss your gym membership yet. Hartmann’s study doesn’t pin down exactly how triclosan and these antibiotic-resistant organisms landed in these gyms.
“The main thing the study can’t tell us is how this all happened.”
“The main thing the study can’t tell us is how this all happened,” said Jordan Peccia, an environmental engineer at the Yale School of Engineering & Applied Science, who specializes in the exploration of indoor microbiomes and how they relate to our health. “It can only point to an association, but it can’t tell us if that’s actually happening inside of a building.”
Remember: Triclosan may be banned in soaps, but it is still pervasive in consumer products. So, Peccia said these bacterial adaptations could be happening on the skin of gym-goers who are using triclosan products at home or are exposed to other antibiotics constantly due to an illness.
“And then they could be just shedding antibiotic-resistant microorganisms on the surfaces of gym mats or into the air of buildings,” said Peccia, who described Hartmann’s study as somewhere between an “important step for the field” and “groundbreaking” because it revealed so much about microbial ecology in buildings.
These antibiotic-resistant bacteria could have developed on human skin before they shedded into gym dust. Photo by franckreporter/via Getty Images
But he raises this alternative scenario because he suspects that gyms are generally too dry for bacteria to be active or evolve antibiotic-resistance.
“In a gym environment, which might be around 50 percent humidity, microorganisms aren’t necessarily dead but it’s very stressful to them. They kind of shut down and are relatively dormant,” Peccia said. “In a normal building, most microorganisms are not active … they’re not responding to chemicals.”
So the open question is do antibacterial spray bottles filled with triclosan provide enough moisture to awaken these bacteria and trigger the development of antibiotic resistance? Or maybe our sweaty palms on treadmill railings or “swamp butts” on yoga mats provide the necessary moisture? Peccia’s lab has found that fungus and molds can thrive at 50 percent humidity, and this appears to involve metabolic pathways that were enriched in the bacteria identified in Hartmann’s study.
Lab-based studies show exposure to triclosan can boost multidrug resistance leading to hazardous strains of bacteria, but it is unclear if this also happens in the general environment. But both Hartmann and Peccia think that antibiotic resistance is a big enough public health threat in places like hospitals that it’s worth just assuming that this is an issue for gyms right now.
Before you use that spray bottle, you should probably ask what’s in it? Photo by Marko/via Stock Adobe
Triclosan, Hartmann said, has all of the characteristics of what’s called a “persistent organic pollutant” — meaning just because we stopped using it in one context (hand soap), doesn’t mean that it is just going to disappear from the environment. Her lab is currently assessing if other disinfectants can spawn this tainted dust and which surfaces inside of a gym contain the highest amounts.
Until then, people should avoid using triclosan and potentially similar sanitizers because “there’s so little evidence justifying the use of these chemicals in the first place,” she said.
If you’re one of those gym attendees who likes to use the cleaning sprays (this is me), she said first ask an attendant: “What’s in that spray?” If it’s just water, then go to town. But if it has triclosan or benzalkonium chloride, which is more common in gyms these days, she said think twice before spraying it if you’re worried about antibiotic resistance. You could always just wipe the machine down with a plain towel.
If you’re nervous about cleaning your hands — because the triclosan ban didn’t apply to hand sanitizers — Hartmann said you should follow the Centers for Disease Control and Prevention’s advice of using plain ol’ soap and water.
Just make sure to lather and scrub for at least 20 seconds — one study of 3,700 bathroom users found people only wash their hands for six seconds on average (this is also me).
“Anything we can do to try to contain the problem of antibiotic resistance, we should be doing,” Hartmann said.
Left: A survey of dust in 42 athletic facilities in Oregon found living germs that were resistant to common antibiotics in all but one facility. These germs arose potentially because of the widespread use of triclosan in sanitizers and other everyday goods. Photo by StockPhotoPro/via Stock Adobe
By — Nsikan Akpan
Nsikan Akpan is the digital science producer for PBS NewsHour and co-creator of the award-winning, NewsHour digital series ScienceScope. For secure communication, he can be reached via Signal (240) 516-8357 or PGP Fingerprint: 06D0 E6A5 AC19 3074 13B0 9F87 A332 744F E4D1 95DF.
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