Hacker News Reader

Comment by ben7799 | Hacker News Reader

I thought bleach and alcohol were thought to not create pressure for resistance because of their nature.

It is interesting they talk about benzalkonium chloride, that stuff absolutely destroys my hands.

When the FDA shut down triclosan all the soaps for paranoid people switched to Benzalklonium Chloride. That stuff absolutely destroy my skin. No matter what anyone complains about they won't stop putting it in all the bathroom soap dispensers in our office. I can go in with my skin fine, if I wash my hands 3x in a day they are almost bleeding by the end of the day.

Also interesting Benzalkloium Chloride last time I looked was in limbo with the FDA, they couldn't decide whether to officially approve it or ban it. They know it causes contact dermatitis. It is currently in a state where the manufacturers are preparing evidence to get it approved but yet it is allowed to be on the market.

View on HN

"I thought bleach and alcohol were thought to not create pressure for resistance because of their nature."

Agreed, and I missed if this article stated otherwise. Also we have been adding chlorine (the active ingredient in bleach) to our water supply for over 100 years ago and that experiment hasn't produced resistant microbes AFAIK.

The article is obviously not proposing a strong suggestion. It even seems to create a case against bleach and alcohol which are least risky and probably very cheap.

I think they will create pressure but having chlorine rip apart your cell membrane seems different enough from disrupting pathways (or something else like an antibiotic does) that it seems as though it would be considerably harder to evolve against.

There are things like microbial cysts that are already protective in these cases but the tradeoffs for the organize are pretty large to adopt something like that. https://en.wikipedia.org/wiki/Microbial_cyst

I don't think there's a way of killing microbiota that creates no pressure for resistance, that's just evolution.

Of course some adaptations are more likely than others, but from a pedantic point of view "use sparingly" is all we have.

I think in this case it destroys the cell walls, so they’d have to completely evolve how cells work in order to evolve. Thus by definition, if they evolved to survive these substances, they’d be an entirely different organism.

anything evolving in any way at all makes it a different organism. evolution is the word for organisms changing at the population level.

I don’t think you understand. Like it would have to evolve into an entirely different class of life, it would no longer be “bacteria” thus “bacteria” can never become resistant to it because to become resistant means that it is no longer “bacteria”

You can't outgrow your lineage in evolution. We're monkeys. KFC is made of dinosaurs. Anything descended from bacteria would still be bacteria.

They would change taxonomy to archea (see MatrixMan’s comment) thus no longer being bacteria.

These are all human issues, the “archea-bacteria” wouldn’t care what we called it, but fun to think about.

> Like it would have to evolve into an entirely different class of life

what do you know what it would have to do? sure, bleach dissolves bacteria cell walls, so for a change to make bleach coming into contact with cell walls not dissolve them would make the cell walls not belong to a bacterium, but what if the bleach that you apply to a surface to kill bacteria is prevented from making contact with the cell wall of a bacterium through some unforeseeable adaptation of that bacterium? now it's resistant to bleach but still a bacteria, and now it's out-reproducing other bacteria.

what adaptation would cause that? no one could say, it's _unforeseeable_.

the actual situation of interest isn't bleach coming in contact with bacteria, it's humans trying to disinfect surfaces by applying bleach.

> they’d be an entirely different organism.

Yeah, they'd be archaea instead of bacteria, which is a huge taxonomic leap, but they'd probably make you just as sick as before.

The naming hierarchies of taxonomy are somewhat justified within eukarya because we have family trees, but when you only have one parent and get your genetic diversity via horizontal gene transfer with your peers, taxonomy is just the words of silly humans.

I wouldn't be surprised if mutations happen that take populations across that boundary all the time. It happened at least once, what are the odds of it happening only once?

-----

New-cell-wall technology aside, I think there are other reasons to avoid frequently creating unnecessary sterile zones. At those zones' boundaries you're creating situations that favor rapid recolonization, neighbors-be-damned, potentially at the expense of equilibria-seeking behavior. Fewer Ghandis more Ghengis Khans.

There's a great radio-lab podcast (titled Argentine Invasion) which describes how conditions like these (regarding a floodplain, in this case) lead to the evolution of an especially ruthless species of ant. It seems likely to me that you'd see the same thing in bacteria populations that are frequently partially obliterated.

One approach is just to starve it of resources such as food or water.

That would promote spore formation in spore-forming bacteria. And spores are more resistant to damage than active bacteria. And spores can stay viable for years.

Fun fact, if you have spores you can create the conditions for them to become active for 24 hours or so. Then you can use a sanitizing method that's less intense. This is sometimes used in mushroom cultivation.

Yes, but if it is something extremely devastating, it might take millions of years of consistent use. Maybe e coli can figure out how to live in an autoclave after a million years, but humans will probably stop using autoclaves before then.

Depending on the temperature, prions can survive at the lower ranges. 2.5% bleach solution will denatured them though.

Prions are not living and do not evolve.

Well, it seems that you can have new prion diseases emerge. Not technically evolution since it's not reproduction, but still a similar theory where new proteins or folds could create more resilient structures. Even for true evolution you're looking at variations in sequences leading to both better and worse states.

The point is, not all autoclaves destroy everything today.

For microbes bleach is the equivalent of a cluster bomb. If you know it's coming you can evolve to decrease the odds of it killing you, but if you don't know it's coming there's nothing you can do.

One thing some bacteria can do is create spores. These are a main reason various disinfectants, including dilute bleach mixtures, say they kill 99.999% of germs, and not 100%. Spores are highly, though not totally, resistant to damage. They can even survive autoclaving at standard autoclave temperatures and pressures. But making spores is the equivalent of sticking baby Superman in a pod and sending him to Earth. Spores are the next generation, the adult generation still dies.

There are apparently better chlorine disinfectants than bleach which show good activity against spores: https://www.cdc.gov/infectioncontrol/guidelines/disinfection...

> Alternative compounds that release chlorine and are used in the health-care setting include demand-release chlorine dioxide, sodium dichloroisocyanurate, and chloramine-T. The advantage of these compounds over the hypochlorites is that they retain chlorine longer and so exert a more prolonged bactericidal effect.

> In vitro suspension tests showed that solutions containing about 140 ppm chlorine dioxide achieved a reduction factor exceeding 10^6 of S. aureus in 1 minute and of Bacillus atrophaeus spores in 2.5 minutes in the presence of 3 g/L bovine albumin. The potential for damaging equipment requires consideration because long-term use can damage the outer plastic coat of the insertion tube. In another study, chlorine dioxide solutions at either 600 ppm or 30 ppm killed Mycobacterium avium-intracellulare within 60 seconds after contact but contamination by organic material significantly affected the microbicidal properties.

> One thing some bacteria can do is create spores.

Spores and biofilms. Biofilms not only protect against antibiotics but also bleach. Some of them repel water better than Teflon. https://www.pnas.org/doi/10.1073/pnas.1011033108 "The biofilm surface remains nonwetting against up to 80% ethanol as well as other organic solvents and commercial biocides across a large and clinically important concentration range."

> I don't think there's a way of killing microbiota that creates no pressure for resistance, that's just evolution.

In order for evolution to function[1], there needs to be differential survival. That is to say, some variants of bacteria must survive at greater or lesser rates than other variants.

For something as strong as bleach, given sufficient concentration and working time, it's not clear to me that that effect exists. My understanding is that it's so powerful and it's means of action is so robust that is just kills everything equally.

---

1. Yes, technically evolution never stops and always functions. I guess a more precise way to word that is: in order for there to be an observable evolutionary effect.

yes, but the difference between having your biological processes disrupted and being smashed with a rock are pretty significant, and the evolutionary responses are quite different.

I am grateful you mentioned this. I recently got frustrated wondering why my hands seem to dry, crack, and bleed so much when I stay over at a certain household. It really makes a lot of other things difficult for days when that happens. I believe they buy antibacterial hand soap, and their water makes it hard to rinse off completely. I will now make sure to bring my own when I visit.

There's concerns for resistance in some non-bleach compounds, especially chlorhexidine.

Bleach though remains pretty much microbial napalm, with some exceptions (prions, norovirus & C. difficile spores at the dilutions a lot of people use).

By far the bigger risk for bleach, IMO, is chemical exposure hazards.

it's easy to accidentally create chlorine gas (this will easily and painfully kill people) and if anyone read the article that's exactly what the concern is here with bleach.

I've been known to carry a small bottle of Dr Bronner's for this reason. Also, the bleaching agents in a lot of commercial paper towels also chew up my hands. I'll carry a few handkerchiefs in the winter too.

> Also, the bleaching agents in a lot of commercial paper towels also chew up my hands.

Are you saying if you wet a commercial paper towel with plain water and drop it on some cloth it will bleach the fabric? Why would the bleaching agents still be active any more than with printer paper or toilet paper? Wouldn't these be a hazard if someone wiped ammonia with them?

Yeah I'm confused about that too. Not to mention most commercial paper towels are the brown unbleached kind. Meanwhile toilet paper I've never seen unbleached...

But there is something I've also always found very mildly irritating specifically about unbleached brown paper towels, as well as uncoated corrugated cardboard. Just kind of like a micro-scratchiness.

I'm not a pulp engineer, so odds are I said the wrong chemical class. Maybe it's a detergent/surfactant? I'm not sure.

You can bring in your own soap, either in a dispenser that you keep at your desk and take to the bathroom whenever you need it, or use a travel-sized bottle that you can keep in a pocket.

Whenever anyone says "you can just," they're probably being unreasonable and not understanding the problem.

I wouldn't tell someone to bring their own soap unless they're travelling to a 3rd world country. It's quite reasonable to expect basic hygiene products to not destroy your hands.

> No matter what anyone complains about they won't stop putting it in all the bathroom soap dispensers in our office.

Sounds like someone in HR just is ignoring the requests. Someone should call OSHA.

I take my own soap when I travel for work in western europe because you cannot rely on these crappy airbnbs my boss rents to have any when you get there.

I've done it or I wouldn't have recommended it.

You'd hate my workplace. The water there is unspeakably foul (I'm sure it's dangerous to drink), so I bring in jugs of my own.

> Whenever anyone says "you can just," they're probably being unreasonable and not understanding the problem.

Or they're offering a solution that they don't view as being overly difficult.

> No matter what anyone complains about they won't stop putting it in all the bathroom soap dispensers in our office.

Call OSHA, or at least threaten to do so.

I would recommend against threatening to call OSHA. If you're going to do it, just do it (and be sure they keep you anonymous).

Retaliation is a thing.

> Retaliation is a thing.

Over soap?

Over calling OSHA (or, worse, threatening to call them). OSHA is no joke, and employers strongly dislike drawing their attention. Some companies react with the corporate interpretation of "snitches get stitches".

So my advice is that you don't point the gun at your employer in an attempt to coerce them into action. If OSHA intervention is necessary, just call them.

"I thought bleach and alcohol were thought to not create pressure for resistance because of their nature."

I think the most famous example is that bleach (at least at normal cleaning concentrations) doesn't kill MRSA. In theory this would give it an advantage.

Where did you get that information?

"List H: Registered Antimicrobial Products with Label Claims Against Methicillin-resistant Staphylococcus aureus (MRSA) and/or Vancomycin-resistant Enterococcus faecalis/faecium (VRE)"

"5813-50 Sodium Hypochlorite Ultra Clorox Brand Regular Bleach Clorox co."

* https://www.epa.gov/pesticide-registration/list-h-registered...

I'm having trouble seeing the concentration for that product. I assume that's full strength 5-7%. If you look at others on that list, you'll see one at 2% sodium hypochlorite rhat requires a contact time of 5 minutes. Most disinfecting products have less than 5% bleach or are not applied for 5 minutes before removal.

Longer kill time is still killing. MRSA is not any more resistant to bleach than other pathogens.

How many people do you know actually leave a product on a surface for 5+ minutes? If you didn't use it properly, then you didn't actually kill it.

P1: Water doesn't make hot tea when combined with tea leaves.

P2: Yes it does, see <points to directions on how to make tea>

P1: Most people don't bother waiting until the water boils, they just pour it on from the faucet.

What a terrible analogy. If you want to make it analogous to what I'm saying, then your third line would have to be true, and that doesn't make sense for the example you chose.

My point was that just because people do it improperly doesn't mean it doesn't work -- and it was a great analogy.

And my point was that the major issue with the MRSA outbreaks 15 years ago or so were because people weren't using them correctly. They even started looking into new types of sanitizers because they knew the people using them were using them incorrectly. So sure, it theory it can, but in practice it generally didn't. Hence the part of my initial comment about at least not at typical concentrations etc.

Your claim was that bleach doesn't kill MRSA at normal cleaning concentrations. It clearly does because bleach is rated to kill MRSA by the EPA. You are trying to weasel out of it by claiming that people aren't using it correctly, but that doesn't make it not kill MRSA.

People who refuse to concede gracefully are insufferable.

C. difficile spores or norovirus particles would be better examples, imo

There’s just no way that’s true. Bleach rips the electrons right off. MRSA isn’t going to develop immunity to that.

Reply on news.ycombinator.com