
Some Bacteria Are Becoming 'More Tolerant' of Hand Sanitizers, Study Finds - xbryanx
https://www.npr.org/sections/goatsandsoda/2018/08/02/635017716/some-bacteria-are-becoming-more-tolerant-of-hand-sanitizers-study-finds
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pard68
I am impressed. I was under the impression that this stuff works because
alcohol kills basically everything.

Looks like we need to start washing with Everclear now.

~~~
dx87
That's what I thought as well. When I took a biology class in college we asked
why hand sanitizer that kills 99.9 percent of germs is fine, but excessive use
of antibiotics breeds super germs. The professor told us that it just destroys
it at a molecular level, so there's nothing to resist, it'd be like trying to
develop a resistance to being torn apart by a black hole.

~~~
okmokmz
That's my understanding as well. Bacteria cannot survive in alcohol because
the lipid structure in their cell membranes are disrupted and their proteins
become denatured

~~~
lima
It's known that some bacteria can survive just fine in moderate concentrations
(the paper points out lactic acid bacteria in sake, surviving at more than
18%) by means of membrane transporters.

The authors suggest that insufficient concentrations could allow tolerant
bacteria to survive.

> _As alcohol tolerance increases, we hypothesize that there will be skin
> surfaces in contact with alcohol-based hand rubs or inanimate surfaces in
> contact with other alcohol-based cleaning agents that do not receive the
> maximum biocide concentration or contact time required for effective
> bacterial killing._

~~~
okmokmz
Yes, it looks like 70% was required for the resistant bacteria

~~~
ohiovr
70 percent is usually said to be the best concentration as a trade off from
lethality to the microorganisms to the time it takes to evaporate.

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dghughes
Most people don't use it correctly anyway. You're supposed to soak your hands
so they're dripping, rub together and let it evaporate. You see most people
just using a small dot on their palms.

I've also read about a certain rare bacteria that thrives on a food additive.
I cant recall what it was but I remember it was really expensive to make the
suddenly a new methods made it cheap. The bacteria rose as the cost of the
additive went down.

~~~
dubyah
C. difficile & trehalose?

~~~
dghughes
Yes it seems it was C. difficile.

I was on mobile and it was tedious to look. But now I did a search and the
article I linked below mentions "virulent strains of the bacterium Clostridium
difficile".

A brief snippet >Trehalose is an extremely stable sugar, resistant both to
high temperatures and to acid hydrolysis thanks to the glycosidic bond linking
its two glucose units. This makes it valuable for high temperature food
processing, since it doesn’t lead to browning as part of the Maillard
reaction.

Speaking of Clostridium difficile. >...they can grow on this sugar while
others cannot.’

[https://www.chemistryworld.com/news/food-additive-may-
have-g...](https://www.chemistryworld.com/news/food-additive-may-have-given-
deadly-bacterium-its-chance/3008488.article)

------
atomic77
> The researchers used different strengths of alcohol concentrations to combat
> the bacteria, starting with 23 percent. Eventually, at a 70-percent alcohol
> mixture, the bacteria were conquered. Typically, hand sanitizers are 60
> percent alcohol.

Is it simply a matter of using higher concentrations of alcohol? Or is it
possible that bacteria could evolve resistance right up to 100%?

~~~
notanote
A 70% solution is considered the most effective. Higher concentrations of
alcohol (over 90% especially) evaporate more quickly, reducing contact time.
Also, they work too quickly. By coagulating the outer proteins of bacteria
instantly, they form a protective layer that actually stops the alcohol from
penetrating further.

~~~
mmt
Although I agree that over 90% is less effective (and your explanation is
clearer than mine [1]), do you have a reference for 70% (and is it w/w or
v/v?) is the _most_ effective?

Last I read up on it, I found the number to be closer to the European hospital
standard of 85%, although I don't have the reference in my bookmarks, nor do I
recall if it was reflect of scientific consensus, if one even exists on the
topic.

[1]
[https://news.ycombinator.com/item?id=17684070](https://news.ycombinator.com/item?id=17684070)

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xbryanx
I always find it fascinating how much the mechanical aspect of hand-washing
makes it more effective than many other methods of sterilization.

~~~
hammock
Sure it does. You don't shampoo your hair without running your fingers through
it, right?

~~~
themarkn
Man if we shampooed our hair before eating our hands would be extremely clean.

~~~
dragosmocrii
use commas

~~~
themarkn
Not sure who downvoted you because yes I should have used commas not only in
the above comment but also in this one.

~~~
jacobolus
Man (if we shampooed our hair before eating our hands) would be extremely
clean.

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petermcneeley
"have hard shells that make it difficult for alcohol to kill them" It is
likely that such adaptation has a cost. Is alcohol resistant bacteria more
benign inside the human body?

~~~
jimmy1
Also, with only my rudimentary understanding of microbiology, wouldn't just
scrubbing your hands together vigorously, which is already recommended,
overcome that?

~~~
Florin_Andrei
Soap and water should work better every time.

~~~
jonhendry18
Access to a sink isn't always convenient or possible.

~~~
Florin_Andrei
Sure, but dying is even less convenient.

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bloopernova
I wish this article had provides a link to a comparison between the different
hand sanitizing methods.

OK, so alcohol-based sanitizer isn't great. How does it compare to plain old
soap and water? What about foaming liquid soap? How does the big gun of
Hibiclens work out nowadays?

~~~
AngryData
Soap and water doesn't directly kill the bacteria, it dissolves the oils and
lipids that that they live in and washes them away. Some die, but if bacteria
was humans, using soap and water is the equivalent of causing a landslide and
just clearing the entire surface of the area of anything but dirt/skin and
dumping the people/bacteria off the cliff and down the drain.

~~~
JumpCrisscross
> _it dissolves the oils and lipids that that they live_

And out of which bacteria membranes are made.

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kevin_thibedeau
I for one would like to know what happens to the cellulose carrier. It always
seemed creepy to me to slather that over your hands, leaving a nice food
source for new bacteria once the alcohol evaporates.

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dev_dull
Would it be too much just to install little hand washing sinks in front
buildings? I don’t need the germs to die. They can live in the sewer all day
long. I just want them off my hands.

~~~
Fomite
The study is looking in hospitals, where the volume of hand sanitization needs
are much higher than the average setting. And where, interestingly, germs
living in the sewer are causing problems - biofilms in plumbing can easily
recontaminate sink surfaces.

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ohnoesmyscv
Dupe of
[https://news.ycombinator.com/item?id=17677617](https://news.ycombinator.com/item?id=17677617)

~~~
jwilk
(0 comments)

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efficax
we need a new "manhattan" project to tackle the problem of bacterial
resistance. Seriously we should be investing hundreds of billions of dollars
into research into more effective means of controlling infectious diseases.
We're on the brink of reverting to the times before antibiotics where common
infections that are now easily treatable will be deadly and debilitating
again. It's terrifying.

~~~
refurb
It’s concerning, but shouldn’t be terrifying (although the media prefers it to
be).

Even with highly resistant strains, current antibiotics works in nearly all
cases. Physicians are quite careful about reserving the “big guns” for last.
In addition, anti-resistance techniques have been effective with some
resistant strains actually decreasing in prevalence over the past few years.

Do we need to keep researching new antibiotics? Of course. Is it doomsday? No.

~~~
goostavos
Links to whatever you're reading that gives you that confidence/understanding?
The media has me pretty convinced that we're on the brink of a modern medicine
failure

~~~
refurb
Good place to start:
[https://resistancemap.cddep.org/AntibioticResistance.php](https://resistancemap.cddep.org/AntibioticResistance.php)

Three out of the six tracked antibiotic have decreasing resistance rates
(aminopenicillins, amoxicillin, piperacillin). The last two are front-line
antibiotics that have been around for decades. They still work for most
infections.

It's not evident from these graphs, but prior predictions were rates were
going to drastically increase over the past decade. That hasn't born out.

Not saying this isn't a public health concern, but it's also not antibiotic
armageddon.

~~~
philjohn
If anything, the Armageddon scenarios that the media like to play out (which
are utterly terrifying - an end to routine surgery, cutting yourself gardening
potentially being fatal etc.) could have caused a shift in the "I'm ill, give
me antibiotics", so in that way, has been just as useful as other controls put
in place.

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jwilk
Text-only version:

[https://text.npr.org/s.php?sId=635017716](https://text.npr.org/s.php?sId=635017716)

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mrfusion
I wonder what the mechanism is? Biofilm?

~~~
dfsegoat
Evolution and adaptation fundamentally ^.

Bacterial growth is essentially logarithmic / exponential - so all it takes is
a few bacterial cells to have a chance mutation which affords the resistance
to $THING, and the population is back to growing fine in the presence of
$THING, and is ready to spread those beneficial mutations with other bacteria
(in a hospital drain system for instance [1,2]).

$THING could be antibiotics, hand sanitizer - etc.

This basic principle is taught by example in every intro to microbiology /
molecular bio laboratory course.

1\.
[https://en.wikipedia.org/wiki/Horizontal_gene_transfer](https://en.wikipedia.org/wiki/Horizontal_gene_transfer)

2\.
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4117541/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4117541/)

(^) Edit after downvotes: My only point was that the underlying mechanism is
somewhat irrelevant - bacteria will always find a way to break down things
humans put in their environment, even Nylon or radiation.

~~~
tootie
But this is equivalent to humans evolving to drink lava isn't it?

~~~
lostlogin
It’s probably more like humans evolving to drink alcohol, which not all
primates tolerate well. Admitedly here is a difference between drinking it at
10% strength and bathing in 60%.

[https://www.scientificamerican.com/article/origins-of-
human-...](https://www.scientificamerican.com/article/origins-of-human-
alcohol-consumption-revealed/)

[http://www.sciencemag.org/news/2014/12/ability-consume-
alcoh...](http://www.sciencemag.org/news/2014/12/ability-consume-alcohol-may-
have-shaped-primate-evolution)

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pkaye
As someone who does home dialysis and relies on alcohol hand sanitizers this
kind of worries me.

~~~
Fomite
Use high concentration sanitizer and you should be fine.

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cup-of-tea
Hand sanitisers in offices etc. should be outlawed. There's simply no reason
for their existence and using them probably weakens your immune system anyway.
They are useful for situations like camping but that is all.

~~~
sol_remmy
They should be outlawed for camping too... the importance of keeping bacteria
from growing immune outweighs the small risk of getting a stomach bug while
camping

Sanitizer should ONLY be legal for use in hospitals

~~~
cup-of-tea
Yeah, you're probably right. We've used soap for centuries and it works very
well.

~~~
mrfusion
We should ban soap too so bacteria don’t get immune to that.

~~~
mprev
I’m guessing this is sarcasm but soap works through a mechanical process of
helping to push the bacteria off your skin, rather than a chemical process of
killing them.

~~~
droidist2
Interesting. And the FDA banned antibacterial soap?

[http://sitn.hms.harvard.edu/flash/2017/say-goodbye-
antibacte...](http://sitn.hms.harvard.edu/flash/2017/say-goodbye-
antibacterial-soaps-fda-banning-household-item/)

~~~
CaliforniaKarl
Yes, because of the additives that make up the “antibacterial” part. Not
because of the “soap” part.

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avryhof
That's fine. Some bacteria is actually good for you. Even trace amounts of
"bad" bacteria will help build your immune system so you don't need to kill
all bacteria.

~~~
nerdponx
This is about hospital infections, not the hygiene hypothesis.

~~~
tootie
I also have yet to see any evidence that hygiene hypothesis is true or leads
to better long-term health outcomes.

~~~
kristiandupont
The book An Epidemic of Absence presents a pretty compelling case, I recommend
it.

~~~
gruez
a 400 page (tl;dr), non-peer reviewed book (no endorsements from the
scientific community) is probably not the best evidence to present.

