What "hand sanitizer kills 99.99% of germs" really means.

http://online.wsj.com/article/SB126092257189692937.html

by zck • 17 years ago

27 13 17 years ago

online.wsj.com

jws• 17 years ago

The article is a bit of a jumble. I've thought for some time that there should be a "by line" reputation system for the internet in general so we can put karma to print journalists.

I did enjoy the odd juxtaposition of AT&T's 97% wireless coverage number presented as if somehow their deception is a commonly accepted fact.

fhars• 17 years ago

What the article fails to mention is that the surviving 0.01% of a specific microbe (or the ones on the 60th test plate) may just be the strains that are resistant to the common antimicrobial agents in household cleaners, which will then find themselves in an environment without much competition, allowing them to thrive. So regular use of antimicrobial household cleaners allows you to grow your very own unkillable strains of germs (and if you are really lucky you may also get cross-resistancies against common antibiotics), putting you and your household members at a considerably higher risk of severe infections. It's all evolution 101.

Antimicrobial agents should be used sparingly and under strict medical control (just like antibiotics, see the article on MRSA in Norway a few days ago), household cleaning should be done with normal detergents or at most chlorine, which has an unspecific toxic effect on microbes and does not lead to resistancies.

dasil003• 17 years ago

Not to mention that hyper-clean environments are associated with immune deficiencies such as allergies and asthma in children.

hga2• 17 years ago

That's only a theory and as far as I know it's very poor at explaining a lot of the asthma increase we're seeing.

timr• 17 years ago

Eh...you're confusing antibiotic resistance with the fact that alcohol-based sanitizers aren't 100% effective. There are two different things going on here:

1) Most anti-microbials aren't antibiotics. They're compounds that happen to kill bacteria by smacking them with the chemical equivalent of a sledgehammer, preventing them from sticking to things, or some other, broad-spectrum mechanism (i.e. they don't generally work by blocking an ion channel or targeting a specific protein or pathway, as would an antibiotic).

2) Hand sanitizers are a special case of #1, where the vast majority are simply alcohol-based gels. Effectiveness of these is determined by concentration and time of exposure (the longer, the better), and in real life, people don't leave them on long enough to be 100% effective.

For the most part, anti-microbial treatment is broad-spectrum, meaning there's no single thing that an organism can do to escape damage. Membranes are dissolved, cells are dessicated, proteins are denatured. Saying that a bacterium could evolve resistance to this is a bit like saying that if you dropped a car on a group of people, the survivors of the catastrophe would be more fit to survive future car-droppings. It's hard for a bacterium to evolve a protective mechanism against having its membrane proteins denatured, or having all of its critical energetic pathways blocked. The damage is simply too extensive.

bena• 17 years ago

I now know more about hand-sanitizers than I ever did before. Thank you.

Semiapies• 17 years ago

Yes, if microbes are developing resistances to ethyl alcohol, we've got much bigger problems than truth-in-advertising. :)

hga2• 17 years ago

You have a point, but I think you take it too far. E.g. I consciously use a toothpaste with triclosan and use nothing else with that antimicrobial, especially anything having to do with food preparation or dish washing, where it's also popular. That way I only skew the population in one area, my mouth, and don't present it with a skewed population from eating.

The antibiotic cross-resistance issue is very real, since one common albeit imperfect mechanism for that is active pumps in bacteria that try to keep the concentration of nasty stuff inside them at a tolerable level. E.g. from Wikipedia: "Some bacteria have innate resistance to triclosan at low, bacteriostatic levels, such as Pseudomonas aeruginosa, which possesses multi-drug efflux pumps that 'pump' triclosan out of the cell."

And the point of using simple vicious stuff like chlorine is well taken, I seriously doubt anything at all can develop resistance to that. Alcohols, I'm not so sure. Stuff like silver ions are interesting (and I use that for stored water), just don't ingest them in any quantity!

philwelch• 17 years ago

What's really depressing is the huge spike in hand sanitizer sales after H1N1. Don't these people know that antibacterial agents do nothing against viruses?

prodigal_erik• 17 years ago

Alcohol will damage the lipid membrane enveloping certain viruses (including influenza) which helps them enter cells. I for one didn't know until now that some viruses are unaffected because they don't have this.

kasterma• 17 years ago

The article suggests otherwise (though does not quite say so in: And some makers of germ killers wish they could say their products kill the swine-flu virus -- a claim that some can reasonably make.)

RiderOfGiraffes• 17 years ago

celticjames• 17 years ago

How effective is hand sanitizer compared to hand washing? Is hand sanitizer more likely to be used than hand washing? Does the introduction of hand sanitizer reduce infection more than hand washing? It's always more useful to compare to a baseline or a standard practice.

What "hand sanitizer kills 99.99% of germs" really means.

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