
Hospital superbugs are evolving to survive hand sanitizers (2018) - Tomte
https://arstechnica.com/science/2018/08/hospital-superbugs-are-evolving-to-survive-hand-sanitizers/
======
crazygringo
It is not at all clear that the headline is accurate.

It states that after long-term exposure to 23% alcohol (non-deadly), recent
bacteria have a higher survival rate.

But it states that the 70% alcohol level contained in hand sanitizers is
"quickly fatal" and "annihilates bacteria".

I was under the impression that it was impossible for bacteria to evolve
resistance to hand sanitizer precisely because it would be like humans
evolving resistance to 1000°F temperatures -- sheer impossibility physically.

So does it even matter if bacteria are evolving to be slightly more resistant
to lower concentrations of alcohol, but are still killed by the level in hand
sanitizers?

The headline appears to be factually inaccurate -- they're not evolving to
survive hand sanitizers, they're evolving to better defend themselves (by 10x)
against much lower concentrations of alcohol that already weren't wiping them
out in the first place.

~~~
titzer
Generally this is how natural selection works, incrementally over long time
scales. Just a small bias for survival is enough to get the optimization
process to work over the long time scale.

One other thing to think about, one strategy that bacteria have been observed
to employ is that a colony can clump together and develop a kind of film that
protects the entire colony from some chemical that would be fatal to any one
individual cell. This ability is greatly enhanced by individuals having a
greater tolerance to low concentrations and being able to signal to the colony
to begin the defensive response. Bacterial colonies have also been recently
shown to communicate amongst the individuals.

So, the headline could be reasonably construed as accurate, IMO.

~~~
sorokod
It's not the scale of the time, it's the number of generations.

~~~
thaumasiotes
They are related as long as one generation takes a finite amount of time.

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godzillabrennus
We’ve known how to combat this for a while:
[http://theconversation.com/copper-is-great-at-killing-
superb...](http://theconversation.com/copper-is-great-at-killing-superbugs-so-
why-dont-hospitals-use-it-73103)

Copper on the surface of hospital furniture should help a lot.

~~~
umvi
What's to stop a mutation from making bacteria copper-immune?

~~~
Tomte
"The ions prevent cell respiration, punch holes in the bacterial cell membrane
or disrupt the viral coat, and destroy the DNA and RNA inside.

This latter property is important as it means that no mutation can occur –
preventing the microbe from developing resistance to copper."

~~~
sillysaurusx
Wait, is it really possible to say “nature can’t do this”?

I mean, think about the entire history of medicine, and science in general:
how many times have we underestimated nature? Can we actually claim that
nature can’t, under any conditions, evolve copper resistance?

I am a layman when it comes to biology, so I have no idea. But I’ve seen
enough handwavey results in other fields where alarms are going off when I
read that. Perhaps the skepticism is unjustified though.

~~~
Retric
On the other hand sunlight has been killing bacteria for ~4 billion years and
their still vulnerable. So can’t might be a poor word choice, but biology does
have hard limits it needs to deal with.

~~~
thatcat
Cyanobacteria evolved to use the sunlight as energy, but that doesn't imply
that other species could easily evolve that ability.

------
allovernow
I couldn't find anything specific after searching (partly becaus Google
helpful enough to remove any references to time duration, despite such
keywords being in my search query), what roughly is the half-life of
antibiotic resistance in populations of bacteria? Are we talking months,
years, decades, or centuries for resistant mutations to drop out of the
genepool?

~~~
nordsieck
> what roughly is the half-life of antibiotic resistance in populations of
> bacteria?

That's almost certainly gene specific.

Think about human resistance to Malaria: there is a pretty strong downside.

There are probably other resistances humans have that don't really have an
active downside aside from enlarging the genome.

~~~
Filligree
Which does count as a downside, to be fair. The genome has a maximum size set
by the mutation rate.

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marcoseliziario
Geez. Nuke'em from orbit, it's the only way to be sure.

In a more serious note, any biologist here knows if varying the type of hand
sanitizer (e.g. alcohol this week, benzalconium chloride next, then something
else, repeat...) would alleviate the problem?

~~~
dchichkov
Having a diverse skin micro-biome and healthy immune system that maintains it
might alleviate the problem. Only a tiny percentage of bacteria are
pathogenic, >95 percent of the bacteria are neutral or symbiotic (and they do
compete with pathogenic bacteria).

Source:

* recent skin micro-biome review in the Nature magazine;

* [https://stm.sciencemag.org/content/9/391/eaah6500](https://stm.sciencemag.org/content/9/391/eaah6500)

It is tough to eradicate pathogenic bacteria. But it is possible to outcompete
pathogenic bacteria with neutral or symbiotic.

~~~
wtallis
The "and healthy immune system" bit would seem to make your advice
inapplicable to hospitals.

~~~
dchichkov
Strangely enough, it might be applicable to hospitals. What you want in a
hospital is an environment without pathogenic bacteria.

There are different ways to achieve it. It seems that the research like (1)
points toward that bacteria establishes themselves very fast in a hospital,
the environment is dynamically changing and is affected by hospital staff and
patients. There is definitely competition present between MRSA and non-
pathogenic bacteria.

Use of hands sanitizers creates _environmental pressures_ on the bacteria.
Both pathogenic and non-pathogenic (2). Hopefully this pressure is still
_beneficial_. That is, it does diminish the rate of infections.

But one can easily imagine a situation where a MRSA bacteria resistant to a
non-alcoholic hand sanitizer could benefit from absence of non-resistant (and
non-pathogenic) bacteria. And in that case, use of such hand sanitizers would
be shaping the environment in a bad way. MRSA will be catching a ride in the
absence of non-pathogenic competition. In that particular case, relying on the
immune systems of hospital staff to shape the bacterial micro-biome on their
hands (and as a result in the hospital - see (1)) _might_ be better, compared
to the use of _such_ hand sanitizer.

(1) Bacterial colonization and succession in a newly opened hospital:
[https://stm.sciencemag.org/content/9/391/eaah6500](https://stm.sciencemag.org/content/9/391/eaah6500)

(2) Good overview on different environmental pressures here:
[https://www.nature.com/collections/egehbdefja](https://www.nature.com/collections/egehbdefja)

------
ponsin
So is this Reddit comment wrong
[https://www.reddit.com/r/askscience/comments/75p8dn/comment/...](https://www.reddit.com/r/askscience/comments/75p8dn/comment/do7y1z0.compact)
? (wouldn't be the first time)

~~~
onetimemanytime
Everyone there seems to agree with other, they all posted the same comment:
[removed] :)

what a thread...

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rs23296008n1
I feel like there's another way forward against these pathogens which is to
strengthen our own bacteria (on-skin or elsewhere). Not just the immune
system.

A single human is basically a cooperating community of many different
critters. Even the thing we call "human" that is tied to the DNA is formed by
cells that are made of little cooperating communities.

I'm not so much just talking about the immune system here in isolation. All
the other parts. At least remove what makes them "less effective with dealing
with pathogen damage and their miscellaneous shenanigans". I'm assuming that
not everything that pathogens do is cause direct and immediate damage. I'm
willing to guess they start out by stealing resources or making things less
effective.

Am I on right track here or is this just gibberish?

~~~
Nasrudith
You hint at or stumbled upon something known and valid but not really viable.
Pathogens having their niches filled with 'neutral' bacteria makes it harder
for to spread than just fully sterile. However while real it isn't reliable
enough. There is a reason why surgeries involve both wiping down with alcohol
before breaking the skin and prescribing a full course of antibioitcs.

So we couldn't do something like 'lets make good bacteria anti-biotic
resistant' and chug large amounts of penecilin. In addition to the logistical
problems and lack of knowledge for 'approved subsets of bacteria list'. We
can't just say dip scalpels in 'neutral bacteria' for internal surgery as a
replacement for sterilization. Plus if we were to get bacteria to act
beneficially to us that would put them at a competitive disadvantage to their
neighbors who don't spend a bunch of energy on playing immune system. But even
that is getting ahead of ourselves, to be able to make bacteria behave in ways
to reliably replace antibiotics and sterilization would require way more
knowledge than we have.

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perl4ever
If bacteria could evolve to survive high concentrations of alcohol, wouldn't
we already have been wiped out from food poisoning via liquor?

~~~
Nasrudith
Even if it could happen that would probably just be one freak batch of tainted
liquor. Something that extreme would likely fare poorly outside of its extreme
and rare niche in the same way everyone wearing an ordinance disposal suit
wouldn't work very well for a society. If it could survive outside those
conditions it isn't exactly privileged over all of the other bacteria out
there and would cut off its own spread by killing people - even making it
taste foul would stop it from infecting all liquor.

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flyGuyOnTheSly
What's the solution here?

Not to sanitize your hands when existing around and touching immunocompromised
individuals?

Or is there a solution?

~~~
simcop2387
Different cleaning mechanisms. Not sure what that would be but something that
kills them via a different method. That kind of diversity is the ONLY way to
deal with resistance.

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sebasmurphy
[https://ubertoolcomic.com/?comic=no-138](https://ubertoolcomic.com/?comic=no-138)

