SciAm: Antibacterial Products May Do More Harm Than Good

[Einhander Sn0m4n]

Strange but True: Antibacterial Products May Do More Harm Than Good

June 07, 2007



Antibacterial soaps and other cleaners may actually be aiding in the development of superbacteria.

By Coco Ballantyne

Tuberculosis, food poisoning, cholera, pneumonia, strep throat and meningitis: these are just a few of the unsavory diseases caused by bacteria. Hygiene—keeping both home and body clean—is one of the best ways to curb the spread of bacterial infections, but lately consumers are getting the message that washing with regular soap is insufficient. Antibacterial products have never been so popular. Body soaps, household cleaners, sponges, even mattresses and lip glosses are now packing bacteria-killing ingredients, and scientists question what place, if any, these chemicals have in the daily routines of healthy people.

Traditionally, people washed bacteria from their bodies and homes using soap and hot water, alcohol, chlorine bleach or hydrogen peroxide. These substances act nonspecifically, meaning they wipe out almost every type of microbe in sight—fungi, bacteria and some viruses—rather than singling out a particular variety.

Soap works by loosening and lifting dirt, oil and microbes from surfaces so they can be easily rinsed away with water, whereas general cleaners such as alcohol inflict sweeping damage to cells by demolishing key structures, then evaporate. "They do their job and are quickly dissipated into the environment," explains microbiologist Stuart Levy of Tufts University School of Medicine.

Unlike these traditional cleaners, antibacterial products leave surface residues, creating conditions that may foster the development of resistant bacteria, Levy notes. For example, after spraying and wiping an antibacterial cleaner over a kitchen counter, active chemicals linger behind and continue to kill bacteria, but not necessarily all of them.

When a bacterial population is placed under a stressor—such as an antibacterial chemical—a small subpopulation armed with special defense mechanisms can develop. These lineages survive and reproduce as their weaker relatives perish. "What doesn't kill you makes you stronger" is the governing maxim here, as antibacterial chemicals select for bacteria that endure their presence.

As bacteria develop a tolerance for these compounds there is potential for also developing a tolerance for certain antibiotics. This phenomenon, called cross-resistance, has already been demonstrated in several laboratory studies using triclosan, one of the most common chemicals found in antibacterial hand cleaners, dishwashing liquids and other wash products. "Triclosan has a specific inhibitory target in bacteria similar to some antibiotics," says epidemiologist Allison Aiello at the University of Michigan School of Public Health.

When bacteria are exposed to triclosan for long periods of time, genetic mutations can arise. Some of these mutations endow the bacteria with resistance to isoniazid, an antibiotic used for treating tuberculosis, whereas other microbes can supercharge their efflux pumps—protein machines in the cell membrane that can spit out several types of antibiotics, Aiello explains. These effects have been demonstrated only in the laboratory, not in households and other real world environments, but Aiello believes that the few household studies may not have been long enough. "It's very possible that the emergence of resistant species takes quite some time to occur…; the potential is there," she says.

Apart from the potential emergence of drug-resistant bacteria in communities, scientists have other concerns about antibacterial compounds. Both triclosan and its close chemical relative triclocarban (also widely used as an antibacterial), are present in 60 percent of America's streams and rivers, says environmental scientist Rolf Halden, co-founder of the Center for Water and Health at Johns Hopkins Bloomberg School of Public Health. Both chemicals are efficiently removed from wastewater in treatment plants but end up getting sequestered in the municipal sludge, which is used as fertilizer for crops, thereby opening a potential pathway for contamination of the food we eat, Halden explains. "We have to realize that the concentrations in agricultural soil are very high," and this, "along with the presence of pathogens from sewage, could be a recipe for breeding antimicrobial resistance" in the environment, he says.

Triclosan has also been found in human breast milk, although not in concentrations considered dangerous to babies, as well as in human blood plasma. There is no evidence showing that current concentrations of triclosan in the human body are harmful, but recent studies suggest that it acts as an endocrine disrupter in bullfrogs and rats.

Further, an expert panel convened by the Food and Drug Administration determined that there is insufficient evidence for a benefit from consumer products containing antibacterial additives over similar ones not containing them.

"What is this stuff doing in households when we have soaps?" asks molecular biologist John Gustafson of New Mexico State University in Las Cruces. These substances really belong in hospitals and clinics, not in the homes of healthy people, Gustafson says.

Of course, antibacterial products do have their place. Millions of Americans suffer from weakened immune systems, including pregnant women and people with immunodeficiency diseases, points out Eugene Cole, an infectious disease specialist at Brigham Young University. For these people, targeted use of antibacterial products, such as triclosan, may be appropriate in the home, he says.

In general, however, good, long-term hygiene means using regular soaps rather than new, antibacterial ones, experts say. "The main way to keep from getting sick," Gustafson says, "is to wash your hands three times a day and don't touch mucous membranes."

[Starglider]

It's a prisoners dilemma situation; for individuals it always makes sense to get the extra short-term protection, as very large scale co-operation is required to make abstention worthwhile. Which means government regulation, which would be really unpopular.

[Boyish-Tigerlilly]

So essentially, the antibacterial solution acts an environmental pressure, which then leads to natural selection of those organisms that don't have some genetic resistance to it.

That makes sense. Wouldn't that be like killing off all members of a species of deer with a specific trait? The ones without the trait would overtake those with the trait because all the ones with the trait are targeted.

However, is this resistance development a problem in hospitals as well, even if most people didn't use it?? What is to stop any use of antibacterial solutions/antibiotics from causing resistance development. I mean, say you are in a hospital and the staff is using the antibacterial solutions. Wouldn't the same thing happen? The solutions would kill the bacteria vulnerable to it while leaving those that aren't (or as the article says, cause mutations that give resistance)?

I wonder if it's a matter of time or if it can be avoided entirely.

[Aorus]

This is nothing new and unsurprising, especially considering that scientists having been cautioning against using antibacterial agents so liberally for years. Besides, a little action for the immune system now and again is a good thing - unless it's medically necessary, it's not healthy to grow up in a sterile environment.

[Civil War Man]

However, is this resistance development a problem in hospitals as well, even if most people didn't use it?? What is to stop any use of antibacterial solutions/antibiotics from causing resistance development. I mean, say you are in a hospital and the staff is using the antibacterial solutions. Wouldn't the same thing happen? The solutions would kill the bacteria vulnerable to it while leaving those that aren't (or as the article says, cause mutations that give resistance)?

AFAIK, it already has been happening. Used to be that you could nail just about any bacterial infection with penicillin. Alternate antibiotics have been developed for several reasons, especially a combination of the segment of the population with an allergy to penicillin and the fact that there are strains of bacteria that are resistent to it.

[drachefly]

This effect is so widely known that when I did a report on it 13 years ago, it was already an old topic.

The news here is the wide spread of soaps with specifically-acting antibacterial agents. Even that's not all that new, but it's new-ish.

Anyway, this is not the tragedy of the commons -- for almost every purpose, rubbing alcohol would do the job perfectly fine, thanks.
It's the tragedy of marketing people a high-profit specialty product to replace a low-profit general product, and in the process causing immeasurable misery in the general population.

[Admiral Valdemar]

This is so old, I can't fathom why it's worth ink or digital bits anymore. The idea that antibacterial compounds help propagate natural selection pressures for superbugs has been known for years. I was taught this much at GCSE level in high school, it's assumed to be "no shit, Sherlock" at degree level microbiology.

You have soaps that contain Microban or anything else with triclosan etc., get rid of them. I've ranted enough over their use on this board in the last few years.

So essentially, the antibacterial solution acts an environmental pressure, which then leads to natural selection of those organisms that don't have some genetic resistance to it.

That makes sense. Wouldn't that be like killing off all members of a species of deer with a specific trait? The ones without the trait would overtake those with the trait because all the ones with the trait are targeted.

Actually, it's like killing off a prison population full of thieves and murdering psychos until only the hardiest psychos are left to fill the remaining cells. It's not a very good strategy, since you're essentially helping the bacteria become far more effective.

However, is this resistance development a problem in hospitals as well, even if most people didn't use it?? What is to stop any use of antibacterial solutions/antibiotics from causing resistance development. I mean, say you are in a hospital and the staff is using the antibacterial solutions. Wouldn't the same thing happen? The solutions would kill the bacteria vulnerable to it while leaving those that aren't (or as the article says, cause mutations that give resistance)?

I wonder if it's a matter of time or if it can be avoided entirely.

MRSA, VRSA, C. difficile and MDR TB are just some of the fun bugs making a comeback or appearing for the first time ever. In hospitals, especially, it is bad, the UK has had many issues with MRSA as the press love to go on about, which can be easily dealt with by simply washing your hands (bring back matron!). The others, however, are bastards to get rid of. Bacteria are simply too good at surviving and so long as we exist, so to will bacteria. They're not going away anytime soon.

In fact...

tharkûn: Indeed, you're right. I can't believe I forgot about the drugs given out in agriculture to increase yield and there's no way that practice will stop unless you get farmers to accept lesser payment in return. Not on your life.

We also use 70% EtOH and trigene to sterilise tabletops. That should work for most all of what we use. Anything that can adapt to that is far beyond our BSL-2 standard labs.

Just how tough can a bacteria be? Would it be possible to gengineer one that would survive absolutely anything but total incineration?

Bacteria are the most successful organism on the planet, bar none. What takes us thousands, if not, millions of years to adapt to, takes them hours. There are bacteria that will not die in anything less than 220 degrees C heat (as a side note, prion proteins are able to survive incineration quite well, though they're not bacteria). There are bacteria that work perfectly well in -10 environments. There are bacteria that can take 1500 rads, thousands of times the lethal radiation dose for a human and can still fully repair any subsequent damage without a hitch. There are bacteria that live in volcanoes, that eat metal, that live without oxygen, that can eat rock, use light and live in other organisms all at the same time as well as give us methane, nitrogen and carbon. Without them we'd be dead, and yet with them, we have a close relationship teetering on the edge of an abyss.

They quite simply are the ultimate in evolutionary technology, able to analyse, counter and adapt to whatever you throw at them which is why we need any advantage we can get lest we go back to the days where a simple septicaemic infection kills anyone who stubs their toe. I certainly never saw that as a good thing about the mediaeval ages, but until some practices change (most involving sheer greed for profit), it would seem to be closer to reality than you think.

how do you actulaly prevent bacteria from becomming immune or heavily resistant to antibacterial treatments or antibiotics? Can it be stopped reasonably, or is it just one of those "fuck it" because it's gonna happen regardless cases?

I mean, is it just a matter of time, or is there credible way to prevent it? If not, it just seems like a stall tactic.

You can cycle throught common drugs and restrict their usage. In the past, doctors would prescribe antibiotics as the be all, end all of medicines. We'd seen penicillin eradicate common ailments overnight in the '40s, so as far as we were concerned in our atomic age, disease was simply another hurdle overcome by man. That soon turned to a less than rosy outlook when MRSA appeared in the '60s and completely adapted to the newest antibiotics within 18 months of their introduction. The damn thing was showing resistant strains globally, in places where the drug hadn't even been used all the much yet to warrant resistance, but bacteria help their own. The colony still remains important even if the single cell is typically selfish.

If you resist handing out drugs for every common ailment that your immune system can counter and if you tell the idiots with a viral cold or something sternly that a virus can't be cured, then you'll buy some time. Using various drugs to make it harder for any single adaptation to occur works too and helps kill off all the bacteria present. Try not to use broad-spectrum drugs like tetracycline a lot which can affect a lot of microbes, but give others unfair chances than some. Get the patients to go through with their full subscription. All too often the main problem is a correct prescription being given but not fully gone through with. People don't like paying for antibiotics if they already feel better, though they fail to realise that the additional doses yet to have will mean all the infection will hopefully be dead and thus avoid any living to adapt.

And lastly, better R&D into new ways other than the usual antibiotics helps. A lot come from nature based on organisms like plants that have to put up with such infections often, so destroying vast swathes of rain forest is not in our best interests really.

[Aaron]

Yes this is ancient, I remember my mother (who is an RN) talking about when I was in grade school. So thats over 15 years ago now.

[Aaron]

Yes this is ancient, I remember my mother (who is an RN) talking about when I was in high school. So thats over 15 years ago now.

Corrected. Damn, something wrong with my adding tonight.

[Boyish-Tigerlilly]

What seems sad is that a lot of average people might just let it blow over their heads and keep going as usual. That would be unfortunate. This has been known in biology for quite some time, but the people don't seem really apt to change.

[Einhander Sn0m4n]

What seems sad is that a lot of average people might just let it blow over their heads and keep going as usual. That would be unfortunate. This has been known in biology for quite some time, but the people don't seem really apt to change.

The sad part is perceptions amongst people do tend to change rather in the same way a species evolves. People following the old ways die off.