We should learn to love germs

13 September 2016

First appeared in the Sydney Morning Herald on 13 September 2016.

What is the strongest force in the world? A poet may say "love", an economist will swear it is "self-interest", and a physicist will vote for "strong nuclear force". As a biologist, my answer is "evolution". This hidden force has a huge impact on our daily lives, especially as it applies to our interactions with microorganisms, and specifically to the chemical warfare we are engaging in in a futile attempt to rid our lives of germs, and remake our kitchens and bathrooms into gleaming palaces of sterility.

The US Food and Drug Administration has banned the use of antibacterial compounds like triclosan and triclocarban in household products such as liquid soaps. The overall finding of the FDA was that these types of chemicals did not meet the twin requirements of being efficient, and generally recognised as safe. To put this another way, the risks of using these chemicals outweigh the likely benefits.

Microbiologist, Dr Nicholas Coleman, discusses the US Food and Drug Administration ban on the use of antibacterial compounds in household products such as liquid soaps.
Microbiologist, Dr Nicholas Coleman, discusses the US Food and Drug Administration ban on the use of antibacterial compounds in household products such as liquid soaps.

This is not a decision the FDA took lightly, as becomes evident if you wade through its 25-page ruling, and its 70 embedded scientific references.

For many years, it has been clear from in vitro studies that when bacteria are exposed to broad-spectrum antibacterials, such as triclosan, they rapidly evolve resistance. This is one of the purest examples of evolution in action: add a stress to an environment, and organisms are forced to adapt or die. Naturally occurring (but rare) mutants are selected from the initial population, and these proliferate at the expense of their less-robust brethren. Darwin would be pleased.

What is especially interesting (and terrifying) about such experiments is that when the surviving bacteria are tested for resistance to other antibacterial agents, they often have resistance to these, too.

In one experiment, an Acinetobacter strain adapted to triclosan was found to also gain resistance to piperacillin-tazobactam, doxycycline, moxifloxacin, ceftriaxone, cefepime, meropenem, doripenem, ertapenem, ciprofloxacin, aztreonam, tigecycline, and trimethoprim-sulfamethoxazole. All of these are clinically significant antibiotics - these are drugs that save lives. Should we be risking the usefulness of such agents in a quixotic quest to eradicate germs from our bathrooms and kitchens? The FDA did not think so.

Naysayers might say "you can't predict what happens in nature based on lab studies". This is a fair point. Certainly, one of the problems in making policy out of science is that it is difficult to quantify these kinds of phenomena and to make accurate predictions about complex systems. However, studies under real-world conditions such as wastewater treatment plants are beginning to show similar outcomes to lab studies.

The FDA decision appears to be based in part at least on the precautionary principle i.e. the threat from antibiotic-resistant bacteria is too dire to wait any longer for more conclusive and quantitative evidence.

Another line of evidence which informed the FDA ban relates to the lack of effectiveness of these antibacterials. One of the most surprising findings was the evidence these products were not significantly more effective at removing germs than soap and water. When this is combined with the knowledge that these highly chlorinated antibacterial chemicals have a questionable chemical safety profile (some evidence exists for endocrine disruption, for example), the response becomes obvious: why would we subject ourselves to these chemicals in our homes? There is a place for strong antibacterial compounds, and that is in hospitals, where they are genuinely needed.

The FDA's decision to ban antibacterial compounds such as triclosan for household uses is the right one, and Australia's regulatory authorities should follow suit.

Antibiotic-resistant bacteria do not respect international borders, and we must fight against antibiotic resistance as a global community. By our indiscriminate use of antimicrobial chemicals, we are trying to fight evolution head on. It is not a battle we can win. We need to start behaving differently and thinking differently. Can we learn to love germs instead of fearing them?

Original article in the Sydney Morning Herald:

Contact: Katynna Parry

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