Some Bacteria Are Becoming 'More Tolerant' of Hand Sanitizers, Study Finds | Hacker News Reader

Some Bacteria Are Becoming 'More Tolerant' of Hand Sanitizers, Study Finds

npr.org

135 pointsxbryanx101 comments

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.

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.

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

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.

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

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.

Reminded me of this comic.

http://ubertoolcomic.com/?comic=no-138

> Looks like we need to start washing with Everclear now.

It's actually backwards from that. Adding some water to alcohol kills more bacteria than pure alcohol.

See here: https://blog.gotopac.com/2017/05/15/why-is-70-isopropyl-alco...

CA-Legal "Everclear" is actually perfect for this, at just 75.5% ABV.

Ditto VA Everclear. But... if you make a run to WV it's like 95%.

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.

C. difficile & trehalose?

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...

> 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%?

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.

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

> Or is it possible that bacteria could evolve resistance right up to 100%?

Adding some water to alcohol kills more bacteria than pure alcohol.

See here: https://blog.gotopac.com/2017/05/15/why-is-70-isopropyl-alco...

It’s not like an antibiotic. At sufficient concentrations, it seems like the lipids in the cell membrane would simply dissolve.

One of the problems with alcohol-based hand sanitizers is that there's a war between "Kills Bacteria" and "Demolishes Your Hands" - one of the major problems in hospitals is compliance, and the harsher the alcohol concentration, the harder it is to get people to use it.

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

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

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

you want to eat your clean hands, or eat with you clean hands... I like the latter actually. Gives more connection to what you are eating

  if we shampooed our hair before eating 

  our hands would be extremely clean

Can someone identify whether this is correct?

use commas

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

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

"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?

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

Soap and water should work better every time.

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

Sure, but dying is even less convenient.

Those shells are temporary; They talk about endospore forming bacteria. They are very hardy and "dormant", but can reactivate given the right conditions. Bacillus cereus for example can survive rice cooking in the spore form, then reactivate and poison you if you leave the cooked rice out of the fridge long enough.

Biofilms and sporulation are enough of a benefit in hospital environments that I doubt it confers much of a fitness detriment, and there's no promise that even if it does, that that comes in the form of decreased virulence.

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?

As someone with compulsive skin picking who gets LOTS of staph infections, Hibiclens combined with tubes of muciprocin left over from the occasional infection I couldn't knock out myself has saved me easily hundreds in copays (and lots of sunburns from doxycycline). That stuff is miracles in a bottle, I will not travel without it, every household should have some on hand. As soon as something starts getting red and hard and painful, I Hibiclens those sins away before it can even THINK about getting streaky, and within hours it looks and feels SO much better. Plus, it doesn't burn or sting like other antiseptics!

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.

> it dissolves the oils and lipids that that they live

And out of which bacteria membranes are made.

I think there's a (obvious) difference between anti-bacterials and standard hygiene.

We know these organisms adapt, just as they did to (oral) antibiotics. Is there any biological reason why hand sanitizers would be any different?

The key to all adaptive mechanisms is that they have to not kill the bacteria as well.

The mechanism of action for hand sanitizers is to disrupt the lipid membrane - it's possible no adaptation exists to make a lipid membrane resistance to high concentrations of alcohol (or other surfactants) that also still renders it a workable membrane.

The current resistance mechanisms in the study are mostly efflux pumps, which again, may not be expressible to save a bacteria when alcohol is present at volume. Even most antibiotic resistance mechanisms are not actually a binary "Works/Doesn't Work" but rather can fight off the antibiotics at the concentration they're delivered in.

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.

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.

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.

Dupe of https://news.ycombinator.com/item?id=17677617

(0 comments)

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.

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.

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

Good place to start: 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.

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.

Big money generally wants to instill fear in you to sell you peace of mind, so..

But sadly, this is not new news. Unfortunately, it's not sexy in a political and/or mainstream media sense. No one seems interested in owning the problem. Perhaps, again sadly, the only hope is this becoming a national security issue and the DoD throwing its budget weight at it. But if obesity is any indication, that's not going to be enough.

Antibiotic resistance is a major threat, but this one was talking about resistance to cleaning products such as alcohol.

Developing a resistance to them is like developing a resistance against being burned alive. A thicker skin might help you somewhat with mild concentrations, but at the end of the day, basic biology says you can't build alcohol-proof bacteria.

Text-only version:

https://text.npr.org/s.php?sId=635017716

I wonder what the mechanism is? Biofilm?

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

2. 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.

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

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-...

http://www.sciencemag.org/news/2014/12/ability-consume-alcoh...

I see what you are getting at - but it's all about pressure and selection.

For instance Sickle Cell anemia is hypothesized to actually be a defense we evolved against malaria:

https://en.wikipedia.org/wiki/Human_genetic_resistance_to_ma...

People that had that mutation were better able to fight off malarial infections in those environments where it was prevalent - and those genes now are passed on specifically in certain ethnicities, etc.

And likely to other simple organisms which feed exclusively on gamma radiation - https://en.wikipedia.org/wiki/Radiotrophic_fungus

Or those bacteria that feed on bi-products of Nylon manufacture - because their environment is rife with wastewater from it:

https://en.wikipedia.org/wiki/Nylon-eating_bacteria

And humans becoming more tolerant of the heat and regenerating cells and tissue quickly enough to survive.

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

Use high concentration sanitizer and you should be fine.

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.

Oddly enough I'm less worried about germs while camping, then when I'm in civilization. Maybe I'm misguided, but I don't expect to encounter human pathogens in the wilderness.

Human pathogens are also other animal pathogens.

E. coli, Shigella, Giardia, Cryptosporidium and Salmonella can all very happily live in the wilderness, infect multiple species, and can be carried by other campers and their pets.

Combine that with poor refrigeration of food, generally less hand-washing overall (due to the absence of plumbing) and the potentially more serious consequences of those infections (dehydration due to a GI pathogen is a much bigger deal two days from anywhere in the Colorado Rockies than it is curled up on your couch), it's definitely a thing.

https://www.avma.org/public/Health/Pages/Outdoor-Enthusiasts...

https://www.cdc.gov/family/camping/index.htm

Okay, now you've got me. Thanks for the info.

Happy to help.

When camping I like having hand sanitizer with the toilet paper. At other times it seems unnecessary, but the toilet paper is probably a bit less sanitary than what you typically experience in a city since there's water near the fine hole in the ground and you have to handle the toilet paper the next person is going to use more than if it was in a bathroom.

Don’t you think banning an extremely common product in response to one study is an overreaction? From the article:

>"To our knowledge this was the first time anyone had shown hospital bacteria becoming tolerant to alcohols," says Timothy Stinear, a coauthor of the study and a researcher at the University of Melbourne's Doherty Institute for Infection and Immunity.

Not really, I think there's a broad consensus that excessive disinfecting across society now has negative rather than positive effects.

Bacteria can plausibly develop resistance to just about anything so gratuitously adding antibacterials to the environment is pretty inherently bad - use them when and only when needed (antibiotics in meat being another problem example).

Also, it seems there's a threshold below which a lack-of-exposure to bacteria and other immune-vectors is actually bad for a person - by preventing the immune system from acting normally.

It's funny, because I remember have arguments with biology majors. And them explaining how alcohol is different and bacteria will never be able to evolve immunity to it unlike anti-biotics. Something I couldn't understand. And they kept trying to describe how it's different, and something about how any bacterium that evolved to survive in an high alcohol environment would no longer be able to survive in a non-alcohol environment. So they would die, just laying on the ground or any surface.

I still never got it.

Bio majors, is thete any truth to that? This article seems to say no. What phenomena could they have been referring to?

Well,

There's understanding what has been experimentally determined so-far about bacteria and organisms and there's understanding that the realm of things we haven't so-far discovered about organisms and their potential evolutions may larger than what we have discovered.

All this talk makes me think of the 'unkillable' T1 phage. Just a tidbit copied from the internet[1]:

'T1 is not easy to get rid off. The best solution of all is to not use T1-sensitive strains. You’ll need to bleach the hell out of everything as well as UV irradiate if possible. And I mean everything, water baths, glassware, specs, pipets, your wife and kids (the latter is probably deserving of a good bleaching anyways). This is serious business T1 can exist in aerosol form for up to a few months, so it’s going to take regular cleaning and testing intervals. In a previous lab it took about six months to a year of solid effort to eradicate our T1 infection.'

[1]http://genrepair.scientopia.org/2011/01/11/do-we-have-a-t1-p...

> 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.

That, or we could just make sure we use sanitizers that have high concentrations of alcohol in these settings.

The bacteria referred to here require lower concentrations of alcohol to survive. They're not able to survive 100% alcohol (or close to 100%), and it's very unlikely that they could evolve to tolerate alcohol levels that high. The reason we don't commonly use high concentrations of alcohol is that it's more irritating to the skin (for the same reason that it kills bacteria). But in settings where killing bacteria is necessary, dehydrating the skin is an acceptable tradeoff.

> They're not able to survive 100% alcohol (or close to 100%)

IIRC, there's something of a peak in the effectiveness curve below the close-to 100% [1] point for ethanol, having something to do with too high a concentration not actually penetrating cell membranes fast enough when there isn't enough water in solution already. It's been a while since I read up on it. The papers are out there, for the curious.

That said, I also recall the European standard of 85% (w/w?) being far better as a disinfectant, as supported by the evidence, than the US minimum of 62% w/w (or 70% v/v). Perhaps instead of a ban, merely increasing the minimum percentage to something that doesn't encourage resistance would be enough.

[1] 96.5% or thereabouts is the highest distillation concentration, above which it would be hygroscopic and come down to that if left open to air.

Thanks, that makes me feel better about buying hand sanitizer and adding 99% rubbing alcohol once it’s half gone because i’m cheap :)

That was actually another detail I discovere, although with much less data behind it, that mixtures of ethanol and isopropanol [1] could be more effective than just one alone.

Mixing the two works well for liquid formulations, where the dispenser is a fine mist sprayer, but I'd be concerned that anything gelled or with additives for a foaming dispenser might not mix evenly enough.

[1] The usual alcohol in "rubbing alcohol" and, of course, for the previously-mentioned reason, ethanol is excluded if it's 99%

"But in settings where killing bacteria is necessary, dehydrating the skin is an acceptable tradeoff." Only if doesn't hurt hand hygiene compliance.

Alcohol sanitizer dispensers could also have a separate moisturizer dispenser.

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

It is not a small risk. Being stuck in the backcountry while losing fluids and nutrients to a GI infection can be a life-threatening situation. Hygiene is in short supply out there to begin with, so it’s very important to have clean hands when handling food and water.

Alcohol-based hand sanitizers aren't effective against noroviruses, etc. viral gastroenteritis anyway. Campers should be using soap if they actually want their hands clean (and wash for at least 10 seconds).

https://www.cdc.gov/norovirus/about/prevention.html

Yeah, you're probably right. We've used soap for centuries and it works very well.

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

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.

Interesting. And the FDA banned antibacterial soap?

http://sitn.hms.harvard.edu/flash/2017/say-goodbye-antibacte...

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

stickier bacteria?

Very creative idea!

Technically, it does both.

What about people with compromised immune systems from disease treatments or other? Do you think it should be banned for them?

A better solution would probably be to mandate 70% alcohol concentration in all sanitize containers.

If they have a medical need why not have it made available by prescription?

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.

This is about hospital infections, not the hygiene hypothesis.

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

There's actually pretty good evidence now that childhood sanitation is correlated with the incidence of Acute Lymphoblastic Leukemia (ALL). Edit: accidentally wrote inversely

Here is a pretty good overview:

https://www.medscape.com/viewarticle/897242

Note that this is a little different than the usual interpretation of the hygiene hypothesis.

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

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

That's true, but when it comes to hospitals, you want to try and minimize all bacteria. Your skin may be a very protective organ, however if you get those same bacteria in a wound, it could lead to dangerous infection.

This. While you're hospitalized is not the time to be trying to build your immune system's character.

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