Germs

[Skeptic Ginger]

I carry alcohol gel hand sanitizer pretty much all the time during cold and flu season, and I at least keep it in the car year round. I try to avoid products that include antibacterial agents like Triclosan (not sure if the specific product mentioned is one of these or not). Overuse of these antibacterial agents leads to increased resistance in some bacteria. One significant consequence is that this makes infection control in clinical settings more difficult.

Just out of curiosity, do you have any links to articles looking at Triclosan resistance?

 

[Skeptic Ginger]

...Bacteria can't really evolve alcohol tolerance the same way they can evolve antibiotic resistance, ....

What do you base this on? It's my understanding that not only can they evolve alcohol tolerance, some have evolved that actually consume alcohol as their energy source.

I'll see if I can find the organism.

 

[Skeptic Ginger]

Speaking of grade schools, the schools in our area have banned the kids from having the hand cleansers due to the cleansers containing alcohol. Zero Tolerance Policy. I guess they thought the kids might drink the hand cleansers.

One of the hospitals I do work for also has to keep the bottles out of patient's hands.

However, unless my son's school could prove to me kids were actually drinking the stuff, I'd be in the principal's office screaming about such a policy. I successfully did the same when my son's school banned water bottles (supposedly because of the litter problem). The drinking fountains are a terrible source of infection spread. I won my battle.

 

[Skeptic Ginger]

There doesn't seem to be any placebo controlled study done yet. One with plastic bottles of plain water.

My feeling is that the ever-present plastic bottles act as a reminder to wash up.

Probably a strong, disagreeable perfume in the bottles would do as well. It would remind you not to get hands near faces without washing first.

The bad taste of the alcohol on your fingers reminds you not to put your hand in your mouth.

As for the placebo, see my earlier post. You don't need a placebo study in every case. Should scientists test placebos every time to study the biological effect of a toxin on an organism?

 

[Skeptic Ginger]

The fellows on Science Friday were not talking about clinical settings, they were referring to ordinary everyday situations.

We use a lot of the stuff in police work, for the expected reasons.

I can well remember my mother (born in the 20s) going on and on about "germs". Likely the realization that microbes cause most disease was just coming into the knowledge sphere of the general public back then.
As I began to read about such things, I tried to explain that her extreme "scrubbiness" was not only unneccesary but ineffective.....Didn't make much impact.

And how do you know that?

Handwashing prevents the spread of infections. The jury was in on that long ago. Keeping your raw meat away from foods you eat raw prevents infection. Jury's been in on that one as well.

This modern fad that one needs to expose one's kids to dirt is based on someone's hypothesis about asthma, and some preliminary data on the immune response. It isn't based on good data just yet, whereas the handwashing and food handling is.

 

[Skeptic Ginger]

...
I can't see any reason to use them in a domestic setting though, where hand washing with soap is perfectly adequate.

Really? You suggest we all find the sink at the grocery store after pushing the cart someone's kid was slobbering on and using the pen everyone uses? There are dozens of places I use the handcleaners after touching the objects hundreds of people touch. I don't go looking for sinks in every building.

 

[Skeptic Ginger]

Even if it kills all types at 99.99% efficiency, the 0.01% residue is going to consist mostly of those that are resistant to the antibacterial agents in the hand wash. It won't take them long to repopulate your hands, but now your little bacterial colony will be slightly harder to get rid of with the hand wash.

Rinse and repeat...

Resistance to disinfectants is much slower to develop.

 

[Ziggurat]

What do you base this on?

The fact that bacteria are the original source for most antibiotics. Obviously those bacteria producing them must be resistant to what they produce (they make the stuff to kill competitors). So the genes for resistance are frequently already out there. Antibiotics also typically act in a rather selective fashion, which is why they can kill (or impede) bacteria effectively without posing much problem to the host. Adaptations to resist them may be relatively minor. Alcohol, on the other hand, is very broad spectrum: it can denature lots of different proteins, including many critical ones in the cell membranes which keep the innards of a cell from spilling out. Which is why it's toxic to the host too, and why alcohol can't be ingested to fight an infection.

It's my understanding that not only can they evolve alcohol tolerance,

Some tolerance, sure. But adaptations to live in very high alcohol environments would probably require far more modifications than antibiotic resistance does, because alcohol disrupts cellular activity across such a broad range of functions. And making such adaptations would, I suspect, put such bacteria at serious disadvantage in low-alcohol environments (like our body), much like thermophile bacteria don't thrive in the cold. Even antibiotic resistance can actually be a competitive disadvantage in the absence of those antibiotics. Nothing is free, and the more a bacteria changes to adapt to one set of conditions, the less well-adapted it tends to be for other conditions. So while antibiotic resistance is a problem for us since we want to be able to make the body an antibiotic-filled environment, we can't make the body a high alcohol environment, so it's not really a problem if the bugs do become alcohol resistant.

 

[Skeptic Ginger]

If "resistance" is taken to refer to changes to the bacterial genome which constitute adaptations to the effects of the antibacterial agents in the hand wash, then no -- not if the active ingredient is alcohol. If the stuff is strong enough (the recommendation is for between 60 and 80 percent for ethyl, lower for isopropyl), and if it is applied thoroughly, there aren't going to be any survivors. Bacterial spores are another matter. These are "resistant" in a somewhat different sense, and killing them would require washing with chlorine bleach, in concentrations strong enough to burn your skin.

I hate to tell you guys but alcohol does not kill every microorganism. See my posts above.


Guess I should elaborate on the Norovirus controversy before someone posts all the official guidelines claiming the waterless alcohol cleaners are effective against it.

Norovirus has been a bugger to culture in labs so growing some to test the effectiveness of alcohol has not been practical commercially which is what one needs to do to satisfy the FDA. So manufacturers use Inactivation of feline calicivirus, a surrogate of norovirus (formerly Norwalk-like viruses), by different types of alcohol in vitro and in vivo to test their products. Some researchers don't agree this proxy virus is really representative of Norovirus. But being the wishful thinkers the people who want cures are, only a few diehard skeptics such as myself are unwilling to say the evidence is in. Public health officials OTOH, really really want to tell you what to do about Norovirus. So they print lots of guidelines saying use the alcohol based hand cleaners.

These data suggest that norovirus possesses greater thermostability than this commonly used surrogate.

Similar inactivation levels were achieved with NV, but generally NV appeared more resistant than FCV, and consequently, the suitability of FCV as a model for NV should be considered with caution.

And I love the conclusion of this study:

MNV-1 was stable across the entire pH range tested (pH 2 to 10) with less than 1 log reduction in infectivity at pH 2, whereas FCV was inactivated rapidly at pH values < 3 and > 9. FCV was more stable than MNV-1 at 56 degrees C, but both viruses exhibited similar inactivation at 63 and 72 degrees C. Long-term persistence of both viruses suspended in a fecal matrix and inoculated onto stainless steel coupons were similar at 4 degrees C, but at room temperature in solution, MNV-1 was more stable than FCV.

So despite all the ways these viruses were not the same,

The genetic relatedness of MNV-1 to human NoVs combined with its ability to survive under gastric pH levels makes this virus a promising and relevant surrogate for studying environmental survival of human NoVs.

There may be more studies since I last followed up on this. Perhaps someone here can cite one that is more current and resolves the controversy.

 

[Ziggurat]

I hate to tell you guys but alcohol does not kill every microorganism.

Yeah, but I said that alcohol cuts across the entire bacteria spectrum, not the entire microorganism spectrum. And given that virii in the environment don't compete for resources the way that bacteria do (since they don't reproduce outside a host), the issue of killing off "good" microorganisms that might combat them seems like it would be largely absent.

 

[Skeptic Ginger]

The fact that bacteria are the original source for most antibiotics.

Penicillin, cephalosporin and tetracycline all came from molds, not bacteria. And we are talking about disinfectants, not antibiotics. I agree the resistant genes are circulating widely and perhaps emerged before the antibiotics were developed.

... Alcohol, on the other hand, is very broad spectrum: it can denature lots of different proteins, including many critical ones in the cell membranes which keep the innards of a cell from spilling out. Which is why it's toxic to the host too, and why alcohol can't be ingested to fight an infection.

You can't ingest scalding water to fight an infection either, but thermophiles exist that can live in temperatures well above boiling.

Did you bother to look at the chart I posted the link to? Not all pathogens are bacteria. Not all pathogens are susceptible to alcohol.


I agree, developing resistance to disinfectants is much more difficult for microorganisms, so if you are simply comparing the differences between anti-infectives and disinfectants, then we don't disagree. It was your wording, "Bacteria can't really evolve alcohol tolerance", and your previous posts that made it sound like you thought it was impossible for organisms to evolve a means of digesting alcohol.

And if you are just looking at the preexisting spectrum of genes:

It is interesting to note that yeast can produce and consume their own alcohol.

Bacteria Culture Propagation

Groups of bacterial cells can, however, utilize other compounds as a source for nutrients like carbon dioxide, carbohydrates and sugar, inorganic salts, amino acids, methane, sterols, hydrocarbons, and alcohol.

 

[Skeptic Ginger]

Yeah, but I said that alcohol cuts across the entire bacteria spectrum, not the entire microorganism spectrum. And given that virii in the environment don't compete for resources the way that bacteria do (since they don't reproduce outside a host), the issue of killing off "good" microorganisms that might combat them seems like it would be largely absent.

But the thread is about preventing infection, and the discussion is about killing pathogens on your hands. And what does competing for resources have to do with anything in this discussion? And there are lots of pathogens that alcohol doesn't kill, not just viruses.

You sound like you are changing your position without admitting you were wrong.

Whatever....

 

[Ziggurat]

You can't ingest scalding water to fight an infection either, but thermophiles exist that can live in temperatures well above boiling.

Yes, I know that. But they don't pose an infectious disease risk, because adaptation to such extreme temperature leads to massive disadvantages at body temperature. And likewise, adaptation to extremely high alcohol levels would likely lead to massive disadvantages at low alcohol levels, making serious infection similarly unlikely.

Did you bother to look at the chart I posted the link to? Not all pathogens are bacteria. Not all pathogens are susceptible to alcohol.

I understand that, and I don't think I ever suggested anything to the contrary.

I agree, developing resistance to disinfectants is much more difficult for microorganisms, so if you are simply comparing the differences between anti-infectives and disinfectants, then we don't disagree. It was your wording, "Bacteria can't really evolve alcohol tolerance", and your previous posts that made it sound like you thought it was impossible for organisms to evolve a means of digesting alcohol.

You cut off the rest of what I said:
"Bacteria can't really evolve alcohol tolerance the same way they can evolve antibiotic resistance"
I did not intend to imply that they couldn't evolve alcohol tolerance at all.

And if you are just looking at the preexisting spectrum of genes:

It is interesting to note that yeast can produce and consume their own alcohol.

Yeast are what we use commercially to produce alcoholic beverages by fermenting sugar into alcohol. In some beverages, fermentation is continued until the sugar runs out and the yeast starve to death, but in other beverages, fermentation ends because alcohol levels reach the point where it kills off all the yeast. They essentially poison themselves. Consuming some of that alcohol might keep them alive longer by keeping alcohol levels lower, but it won't actually help them much to survive at higher alcohol levels. There's a reason that you have to distill hard liquor, not just ferment it: yeast can't survive in high alcohol environments.

Bacteria Culture Propagation

Groups of bacterial cells can, however, utilize other compounds as a source for nutrients like carbon dioxide, carbohydrates and sugar, inorganic salts, amino acids, methane, sterols, hydrocarbons, and alcohol.

There are lots of organisms which feed on sugar. There are not many organisms which can survive in a very high sugar environment (like honey, for example). The ability of an organism to use a substance as a nutrient does not mean it can survive extreme concentrations of that substance. So it's not enough for a bacteria to be able to break down alcohol.

 

[Audible Click]

Really? You suggest we all find the sink at the grocery store after pushing the cart someone's kid was slobbering on and using the pen everyone uses? There are dozens of places I use the handcleaners after touching the objects hundreds of people touch. I don't go looking for sinks in every building.

The grocery store in our area have alcohol wipes where you pick up the carts(for wiping the handle) and then again at check out. I don't know how much this helps overall but I do see customers using them.

 

[Ziggurat]

But the thread is about preventing infection, and the discussion is about killing pathogens on your hands.

Which means that the statements I made about bacteria specifically do not address the entire topic. I understand this, and never meant to imply otherwise. If that's a point you wish to clarify for other readers, I have no objection.

And what does competing for resources have to do with anything in this discussion?

Quite a bit. There is an idea floating around that killing off good bacteria is harmful, because the bad bacteria have less competition and can thus infect you more easily. The same dynamic is not applicable to virii.

And there are lots of pathogens that alcohol doesn't kill, not just viruses.

OK. What are the others? Well, we've got prions: not much of an issue with them evolving. They are what they are. Hand sanitizers may not help, but there aren't many human prion diseases. But hand sanitizer won't protect you from mad cow disease.

Then we've got coccidia. Which is transmitted primarily by ingestion of contaminated tissue or fecal matter. So if you touch poo or eat raw flesh, yeah, the hand sanitizer won't be enough. The primary coccidia for humans seems to be toxoplasmosis, which is fairly harmless in adults. The lesson? If you're pregnant, wash your hands with soap after taking out the cat litter or digging in the garden.

The only one left on the list for which alcohol disinfectants are listed as ineffective is bacterial spores. The only important human-infectious bacterial spore I'm aware of is anthrax. So all you sheepherders, take note: alcohol hand sanitizers aren't enough.

 

[casebro]

Do you folks think that alcohol wipes might be the reason that the current swine flu is so mild? Me neither.

So, what with all of the jillions of time alcohol wipes have been used, is there any in vitro subjective measure of improvement? Fewer hospital infections, fewer sick days off work, lower kids abenteeism rates? Lower sales of cold remedies? Pepto-Bismol sales have tanked?

See why I think a DBPC study is appropriate?

I wonder how much Big Agra is behind the fad? The sure want us to use ethanol in our cars.

 

[Skeptic Ginger]

....

OK. What are the others? Well, we've got prions: not much of an issue with them evolving. ....

So clearly you didn't bother looking at the chart I linked to listing the organisms unaffected or not consistently affected by alcohol based disinfectants.

The following cannot be reliably disinfected with alcohol based products:

chlamydiae
non-enveloped viruses
fungal spores
picornaviruses (i.e. FMD)
parvoviruses
bacterial spores
coccidia
prions


Alcohol is less effective against the following but can be used:
rickettsiae
enveloped viruses
acid-fast bacteria

 

[casebro]

I'm a homebrewer. I know that some yeast have been bred to live in higher alcohol levels. It's called "Champagne yeast". The alcohol won't kill it so easy, so it eats more of the sugar. It is used to ferment to a dryer state, with higher alcohol levels.

 

[shawmutt]

To skeptichick, skeptigirl, and any others who remarked on the removal of hand sanitizer from classrooms--

It took a class of third graders to show me why. My wife, a schoolteacher, was out one day. She came back the next day to an note from the sub complaining of rowdy kids, police knocking on the door, and an empty box of hand sanitizer bottles. Apparently the kids were huffing the sanitizer, which does have an intoxicating effect.

 

[Ziggurat]

So clearly you didn't bother looking at the chart I linked to listing the organisms unaffected or not consistently affected by alcohol based disinfectants.

The following cannot be reliably disinfected with alcohol based products:

chlamydiae
non-enveloped viruses
fungal spores
picornaviruses (i.e. FMD)
parvoviruses
bacterial spores
coccidia
prions

What are you talking about? This is the link I read:
http://www.cfsph.iastate.edu/brm/resources/Disinfectants/AntimicrobialSpectrumDisinfectants0904.pdf

non-enveloped viruses, picornaviruses and parvoviruses are, rather obviously, kinds of viruses. It was already established that viruses could be alcohol resistant. I covered bacterial spores, coccidia, and prions in my previous response. That leaves chlamydiae and fungal spores, both of which alcohol is listed as having limited activity against. So alcohol isn't a fool-proof disinfectant against them, but it does attack them. But I never claimed it was foolproof against anything, even non-spore bacteria.

Alcohol is less effective against the following but can be used:
rickettsiae
enveloped viruses
acid-fast bacteria

Your chart lists alcohol as being effective against all three. This is not the highest rating (which is "highly effective"), but to call it "less effective" is misleading.