Superbugs Capable of Resisting the Strongest Drugs Found in Hospitals | Hacker News Reader

Superbugs Capable of Resisting the Strongest Drugs Found in Hospitals

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27 pointscaracaleo23 comments

The BBC programme "Horizon - defeating the superbugs" showed an experiment of bugs developing resistance to antibiotics.

They had a large tray (about a metre by three metres?) divided into several sections. At each end was regular gel food. Then in slices the gel had anti-biotics dissolved in it in higher concentrations. In the middle they could not dissolve any more anti-biotic, they had reached the solubility level. (This would have been toxic for people). The bacteria had no problem evolving to this level.

(http://www.bbc.co.uk/programmes/b01ms5c6)

Unfortunately, it's not available on BBC iPlayer anymore.

I ahem 'found' this clip on YouTube. (http://youtu.be/2w38Ry1WHh0)

I wanted to make a glib comment about overuse of antibiotics in farm animals. Reading a little deeper, that 50% mortality rate is really scary. I guess, those are people already in the hospital, so their immune system is already taking a hit, but wow. 50%.

It is reassuring to me that while these "superbugs" are still outside of people they are 100% susceptible to being destroyed by soap and scrubbing.

For some values of "destroyed", including "not destroyed, just dislodged".

Obviously, washing hands with soap and water is important and helps reduce infection. This CDC article has some information about some of the difficulties with this. (EG: Why don't surgeons shower before surgery?) When is clean too clean? (http://wwwnc.cdc.gov/eid/article/7/2/70-0225_article.htm)

Generally soap destroys bacteria through acid-base reactions with the amino acids in the bacteria. As a science experiment we took bacterial colonies we had grown and exposed them to both an anti-microbial solution and a plain soap. The anti-microbial solution causes the bacteria to die, and the soap causes them to explode.

However, in heath care institutions it is impractical to use soap repeatedly due to damage it causes to your skin (for the same reason it damages bacterial cells, it is indiscriminate). Similarly with ultraviolet light sanitizers which also work by destroying the cell material and are equally harmful to your skin and bacteria.

There is an interesting investigation going on into encapsulation, basically having health care professionals change gloves all the time which doesn't kill the microbes on their hands but gives them fresh 'skin' each glove change.

> Generally soap destroys bacteria through acid-base reactions with the amino acids in the bacteria.

I'd like to learn more about what you mean by this, since everything from my biology training has taught me that the mechanism of action of detergents is primarily disruption of the lipid membrane of bacteria--ie. causing lysis and release of cellular contents into solution[1]. The disruption is due to the amphiphilic nature of detergent molecules (they are attracted to both polar water molecules and to the non-polar lipid molecules in cell membranes, ripping the lipids away with agitation of the solution). Amphiphiles are not acid base so much as partially charge-polarized and capable of hydrogen bonding, and partially charge/hydrogen bond neutral. Attaching to lipids and water simultaneously is thermodynamically favorable for them.

It's true that bacterial S-layers are proteinaceous and provide some protection, but detergents are still effective via the above mechanism (though often more so in concert with EDTA, urea, or other agents).

Some bacteria (ex. Streptococcus pneumoniae, Klebsiella pneumoniae, some strains of E. coli) have a capsule that would provide resistance to detergents, but it is generally a structure made of polysaccharides, not amino acids (ie. polypeptide). Bacillus anthracis does have a polypeptide capsule that would serve as a barrier to detergents, but it's an unusual characteristic.

This is not to say that high or low pH (base or acid) cannot destroy bacteria, but it is not the primary mechanism of action of soap or most so called anti-microbial products. "Explode" is not quite the right word for soap (it would be for hypo-osmotic lysis buffer). It really tears holes in the cell membrane.

Some anti-microbial soaps do contain agents that inhibit bacteria through a mechanism other than lysis. Triclosan is in the anti-microbial soap commonly found in hospitals, and it inhibits fatty acid synthesis--preventing bacteria from forming cell membranes. It's typically combined with a detergent though.

Ultraviolet light sanitizers (254 nm light) knock some bonds loose in DNA, causing thymine dimers to form. This doesn't quite destroy them, but it does prevent them from replicating and can inhibit production of harmful gene products by throwing a wrench in transcription.

You're right about soap overuse being damaging to skin, and glove changes are important. One of the most simple changes I've heard suggested is a switch back to brass doorknobs, since the copper kills bacteria via the oligodynamic effect (still not very well understood).

1. http://www.piercenet.com/browse.cfm?fldID=5558F7E4-5056-8A76...

Nice!

Ok, so the acid-base explanation was the one we came up with after observing what soap did to our bacteria under a microscope. The bacteria lost cellular cohesion and became a sort of soup. In the case of anti-microbial soap the bacteria simply ceased replicating (which we interpreted as them being dead).

Our test soap was SafeGuard brand (regular soap) and an antibacterial blend of SoftSoap brand.

If you don't mind I'd like to borrow some of your explanatory text to augment and/or replace some of the material in that experiment for other home schooling parents.

> The emergence of deadly, bacteria resistant hospital superbugs is on the rise according to the CDC.

Given this crisis produced by natural selection, it's amazing to think that only 39% of Americans believe in evolution:

http://www.gallup.com/poll/114544/darwin-birthday-believe-ev...

I thought it was interesting they completely avoided the evolution issue in there response to:

How Do Certain Bacteria Become Resistant?

I suspect the reason is that they want people to read the article without popping their intellectual circuit breakers and going offline. There's no reason to blow off 61% of your reading audience by saying the "wrong thing".

I doubt the same topic would be covered in the same evasive way in Europe, where scientific literacy is higher.

I'd say that number is probably higher - I know a number of people who believe evolution happens but think that humanity didn't evolve from monkeys. Because we are special, or something. I generally don't query further.

> I'd say that number is probably higher ...

It is higher among the educated, and lower among those with a HS degree or less:

http://sas-origin.onstreammedia.com/origin/gallupinc/GallupS...

(Obligatory reminder that schooling is no assurance of education.)

I like to point out, when faced with that argument, that they are right! We didn't evolve from monkeys, we evolved with them from a common ancestor! That doesn't seem to help though...

> We didn't evolve from monkeys, we evolved with them from a common ancestor!

Yes, and (snicker, snicker) we therefore evolved from a creature that was "lower" than a monkey. :)

As I understand it, these guys distinguish between "micro-evolution", such as the current topic, and "macro-evolution", which is the large scale monkey stuff they don't believe in.

I hadn't heard that one. It sounds as though they're painting themselves into a corner.

This reminds me of the rather funny Creationist response to the closing of one of the much-loved "gaps" in the fossil record. When a new fossil discovery appears to close a gap, they proudly announce that they now have two gaps -- one on either side. :)

Natural selection only chooses from existing variations. Obviously "selection" cannot create new genetic information.

Evolution is the result of multiple forces. Mutation and gene flow add variation to a population (mutation creates variation; gene flow imports it from elsewhere). Selection and drift change the ratios of existing variations (selection chooses the "best"; drift is random fluctuation between equally viable variations.) When two different subgroups of a population go through the process separately, over time they can diverge enough to no longer be able to interbreed, and therefore become separate species.

There are those who believe selection works within a species, while simultaneously believing the process as a whole breaks down or is inadequate on some larger scale.

> Natural selection only chooses from existing variations.

No, this is wrong. What we call "natural selection" includes the effect of various sources of genetic mutation. It is by this process that selection (the entire process) does create new genetic information.

Another way to say this is that, without identifying and addressing sources of mutation, natural selection would not be a complete theory.

well, I am not sure, why it is on hackernews, but it growing resistances of bacterias to antibiotics are indeed a huge problem.

If you think about giving birth to your next child in a hospital, think twice about that. Multi resistant bacterias, like methicillin-resistant Staphylococcus aureus are a danger.

A friend of mine and his newborn just had such complications to endure.

New research shows that 4% of hospital patients get infected anually in Germany and another 4% dies from those complications.

Yes, definitely have that C section performed at home. You definitely won't need the services of a NICU available, either.

It's important to note that it would be 4% of those infected die, not "another 4%". That's a little less than one in five hundred die of these particular infections, a far cry from the implied one in twenty five.

While it's bad enough already, note that since bacteria can "hot swap" genetic information it's the CR property itself which is surviving and spreading. This is a pretty fascinating example of evolution at the sub-individual level.

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