Hospital superbugs are evolving to survive hand sanitizers (2018)
arstechnica.com
arstechnica.com
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.
I imagine yes, it does matter.
It's not like hand sanitizer use is absolutely perfect.
Let's assume some bacteria always gets past the direct initial 70% alcohol application, but there's residual alcohol that tends to take care of whatever remains.
As the bacteria becomes more alcohol resistant, those lucky survivors of the initial direct application become more likely to survive the residual effects.
1. The old traits provide protection against a problem that modern bacteria no longer encounter. As such, when changes to the genome interfere with those old protections, no problem occurs and the old protections are lost to genomic bit rot. (If a colony of Tibetans moved into India, over the long term their high-altitude adaptations would deteriorate under a lack of pressure to maintain themselves.)
2. Alcohol resistance is so valuable that +1 alcohol resistance makes up for -3 traditional resistance. This is the sickle-cell anemia model.
There is no conservation law holding constant the total amount of "protection" your genome provides you. If bacteria are adapted to defend themselves against certain risks, and you add a risk of alcohol exposure without removing the other risks, what you'll get are bacteria that (1) resist all the old risks (like the old bacteria did), and (2) also resist alcohol exposure.
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.
Yes - your skin is a mountain range at bacteria scales. And when the hand sanitizer is applied, some bacteria will be hiding in caves and crevices, and only come into direct contact with a much lower or no contact with the alcohol.
Copper on the surface of hospital furniture should help a lot.
This latter property is important as it means that no mutation can occur – preventing the microbe from developing resistance to copper."
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.
Resistance doesn't happen because the anti bacterial agent provokes mutations.
The process is that mutations happen all the time, and those that result in slightly higher survival rates over time dominates the population.
The mutation is a pre-existing condition that is selected for when everyone else dies or has a bad day, and you can now fill the empty space.
> [...] copper and its alloys exhibit these impressive properties and the processes involved. The process involves the release of copper ions (electrically charged particles) when microbes, transferred by touching, sneezing or vomiting, land on the copper surface. 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.
I always understood that the mutation happened at copy time/mitosis.
Copper may well be impossible to develop a resistance against, but it’s not due to the mechanism above. All anti-microbials also destroy their enemy cells, but for some, it’s possible for a random mutation in the population to provide resistance to the antiseptic.
So the question is: is copper like alcohol and fire? Or is it like antibiotics and other more “nuanced” antiseptics?
Similarly, if plants can evolve to tolerate extreme salt concentrations, it should be possible for bacteria to evolve copper resistance.
They spread through the population by being copied when their host reproduces, but they don't have to happen then.
I am extremely sceptical of that statement.
Edit: google for <mutation copper resistance> shows papers that might be relevant arguments that support my skepticism.
In context we are talking about microbes that are developing unbelievable resistance to high concentrations of alcohol: “The alcohols essentially shred the microbes' outer membranes, causing molecular mayhem and the germs’ innards to leak out. In high concentrations, the alcohols are quickly fatal.”
So I wouldn't worry too much. The worst outcome is likely to be hand-washing becoming a somewhat larger nuisance, a higher risk of skin irritation or some combination therefore. The whole procedure is probably ripe for some purely mechanical innovation such as high(ish) pressure water or air, considering that part hasn't much changed in the last 200 years (although training and frequency have increased)
Skin irration is a form of abrasion, which allow bacteria to both hide and feed. Potentially creating a bigger problem.
We (today) might have reservations about calling the new humans "humans", though.
As it turns out we’ve only mined 12% of known copper reserves and once mined copper stays in circulation almost indefinitely because of it’s very high recycle rate.
Can we extract this wealth of materials cost effectively while respecting the ecosystems adjacent to them? What would a high-tech mine look like?
$2.75 is what, equal to maybe 2 mins of the average doctor's hourly salary?
https://www.acs.org/content/acs/en/pressroom/presspacs/2018/...
And that's all are needed to keep them around. I really hope the period of human history with anti-biotics wasn't a small window we got lucky enough to live in, because modern life will be very without it.
Antibiotic resistance is made up of expensive and inefficient adaptions that tend to drop out of the gene pool when those particular selection pressures subside.
From what I've read, cycling antibiotics over time is purported to be one method of fighting resistance.
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.
And as I understand, there isn't much research on that - "a genetic document is rather mute" - https://www.nature.com/articles/s41599-019-0251-8
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?
Source:
* recent skin micro-biome review in the Nature magazine;
* 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.
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
(2) Good overview on different environmental pressures here: https://www.nature.com/collections/egehbdefja
what a thread...
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?
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.
Not to sanitize your hands when existing around and touching immunocompromised individuals?
Or is there a solution?