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marnixR
Post  Post subject: welcome to the post-antibiotics world  |  Posted: Tue Jan 17, 2012 7:02 pm
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so who's going to be the first person in the western world who dies of tuberculosis when antibiotics are no longer usable ?

i'm afraid the following article is only one of many diseases that will make the "cordon sanitaire" as leaky as a sanitary towel

Indian TB cases 'can't be cured'

where's the next generation of miracle medicines when you need them ?

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Hermit
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Wed Jan 18, 2012 12:23 am
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Not surprising that this strain rose in India. India is where antibiotics are most misused. With TB, a very long course of treatment is vital. If patients are prescribed a month of antibiotics instead of the 6 to 12 months they need, which happens a lot in India, it just leads to development of resistance.

Our hope is a whole long raft of new anti-bacterials currently under development. This includes antibodies, polypeptides, sRNA, bacteriophages and a bunch of stuff extracted from various animals and plants.

Just as a f'rinstance. Take the ferocious crocodile. It does battle with its peers in the dirtiest of dirty, crap-laden water. They tear great gouges in each other, which is washed by germ laden liquid. Yet never do any of those wounds get infected. What is its secret? Ahhhh....

In fact, crocodile blood seems to be lethal to all kinds of bacteria, and researchers are hard at work to find out why. And this is just one of many lines of research.


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iNow
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Wed Jan 18, 2012 1:15 am
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Until they do, it appears that the herd may be culled a bit in the relatively near future. We might make the 1918 flu epidemic look like small potatoes. It is 2012, after all. :?

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marnixR
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Wed Jan 18, 2012 7:19 am
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Hermit wrote:
In fact, crocodile blood seems to be lethal to all kinds of bacteria, and researchers are hard at work to find out why. And this is just one of many lines of research.


reminds me of the horseshoe crab test
and there's also the chemical defenses of sponges

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Hermit
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Fri Jan 20, 2012 4:13 am
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iNow wrote:
Until they do, it appears that the herd may be culled a bit in the relatively near future. We might make the 1918 flu epidemic look like small potatoes. It is 2012, after all. :?


We have one big advantage.
Today, we understand about infection and how it is passed on. We might not be able to cure antibiotic resistant tuberculosis, but we should be able to minimise its spread with effective procedures. I could design a ward that would prevent cross infection, using such things as negative air pressures, ultra violet in exhaust fans, fine respirators for doctors, widespread sanitising and so on.

Also, remember that most sanitisers and disinfectants are not antibiotics and work just fine to kill any bacteria, including antibiotic resistant TB. It is physically impossible for bacteria to develop resistance to chlorine, for example. The proper use of such tools will minimise spread of disease.


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CharonY
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Fri Feb 17, 2012 10:53 pm

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In clinical contexts otherwise relative harmless strains that have acquired multi-drug resistances are already a real problem (such as MRSA). There are preventive means but often they are not implemented well enough, interfere with day-to-day operations

Oh, and according to WHO around 500 people died from tuberculosis in the USA (though unclear whether resistances played a role).

Also, while AB resistance is far more widespread and easier to acquire for bacteria (it has been a selective pressure for bacteria for as long as the first bacterium decided to kill off other bacteria), there are strains known to be chlorine resistant. I remember a talk on E. coli where a dozen or so passages resulted in the detection of strains that were about 5 times more resistant than the WT.


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Hermit
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Sat Feb 18, 2012 12:20 am
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Charon

I will disbelieve your claim that some bacteria are chlorine resistant. I suggest you post a reference to back up the claim.

The thing about chlorine is that it is not a subtle effect. It is like attacking tissue with acid. Chlorine is a strong oxidiser and attacks all organic matter. Put your hands into strong chlorine solution for a time if you do not believe this. (Not actually a smart move!). After a time, the chlorine solution will dissolve the outer layers of your skin, and it will hurt!

Chlorine solution, even quite weak, will dissolve the cell membrane of the bacterial cell, resulting in rapid and very final bacterial death!


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iNow
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Sat Feb 18, 2012 1:22 am
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Hermit wrote:
I will disbelieve your claim that some bacteria are chlorine resistant. I suggest you post a reference to back up the claim.

Just a head's up to you, Hermit. This would be a mistake. Charon is QUITE competent and knowledgeable. However, I always agree that sources are helpful.

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CharonY
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Mon Feb 20, 2012 10:03 pm

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Of course. There are in fact too many to name, but here are some:
Cherchi and Gu Water Sci Technol. 2011;64(1):7-13.
Ridgeway and Olson AEM 1982 vol. 44 no. 4 972-98, they showed that there may be selection for chlorine resistance, which was later shown to happen also in Pseudomonas in an Indian paper that I cannot remember right now.

I do not recall the name of the guy who gave the talk but if I remember I can also post that, too, if interested.


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Hermit
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Mon Feb 20, 2012 10:49 pm
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Charon

Since I do not have access to technical libraries, can you try to post references accessible via the internet?

Chlorine is not something that bacteria can simply adapt to. It is like suggesting an animal can adapt to swimming in concentrated sulfuric acid. Chlorine is unsubtle, and simply dissolves the cell membrane. Typically, resistance is developed to things like antibiotics by subtle changes in cell biochemistry. How can a bacterium adapt to chlorine and its corrosive effect?

I am happy to accept that some bacteria can handle higher chlorine concentrations than others, due to different cell membrane structure. But developing resistance to chlorine overall is simply not biochemically possible. Just a moderate increase in chlorine concentration will sterilise any bacterial infection.


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iNow
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Tue Feb 21, 2012 12:21 am
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CharonY wrote:
Of course. There are in fact too many to name, but here are some:
Cherchi and Gu Water Sci Technol. 2011;64(1):7-13.
Ridgeway and Olson AEM 1982 vol. 44 no. 4 972-98, they showed that there may be selection for chlorine resistance, which was later shown to happen also in Pseudomonas in an Indian paper that I cannot remember right now.

I do not recall the name of the guy who gave the talk but if I remember I can also post that, too, if interested.

Hermit wrote:
Since I do not have access to technical libraries, can you try to post references accessible via the internet?

Don't forget to try google first. These were not terribly difficult to find.


http://www.ncbi.nlm.nih.gov/pubmed/22053451

And here's a full article for the second reference provided by Charon, from back in 1982:
http://www.ncbi.nlm.nih.gov/pmc/article ... 9-0214.pdf

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Hermit
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Tue Feb 21, 2012 12:37 am
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Thanks for the references, iNow.

I do not think these are referring to complete resistance, in which bacteria are able to increase in numbers despite a toxin. They seem to be talking more of survival times when exposed. The results are consistent with what I said earlier - that chlorine corrosive attack destroys cell membranes, and this cannot be adapted to. The second paper, for example, talks of greater 'resistance' by clumps of bacteria compared to single cells. This would be true for dissolving in sulfuric acid also. The first paper talks of greater vulnerability during growth phases than during lag phases. Nothing surprising there.

I do not think that either paper is, in fact, referring to classical bacterial resistance, as something gained by adaptation from exposure. Rather, the time taken for the robust physical action of chlorine to sufficiently break a cell membrane.


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CharonY
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Tue Feb 21, 2012 5:33 am

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Sorry, there is basically no such thing as complete resistance. Almost all resistance mechanisms can be eventually overwhelmed (or secondary toxic effects may occur). Second, classically resistances are not gained by habituation or adaptation to exposure (for some reason this is particular persistent myth with a tiny little grain of truth), but by selecting for bacteria that have a higher resistance to begin with.

Note that in the first paper they described that two E coli strains (i.e. same species) have different level of resistance patterns. This indicates that mechanisms exist (and again, note that we are talking differences on the strain level) that allow differences in resistances. The older paper shows that resistance differences in the order of one order of magnitudes exist on between different bacteria. Again, indication of resistance strategies.
Here is the other paper that shows selection for chlorine-resistant P. aeuginosa strains Ecotoxicol Environ Saf. 2004 Jun;58(2):277-83. at 500 µg/L.
What is generally true is that resistances to harsh chemicals (including e.g. ethanol) are much more concentration constrained than e.g. for antibiotics (what you probably refer to as classical). As such resistance mechanisms are also much more limited. Claiming that none exist is pretty much inaccurate, however.


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Hermit
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Tue Feb 21, 2012 5:58 am
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Charon

We may be arguing semantics. That is : what is acquired resistance?

The resistance I am talking of, like antibiotic resistance, is dramatic. Once resistance is gained, the target organism can easily tolerate a very large increase in the toxin. Say ten fold.

This does not happen with chlorine.


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CharonY
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Tue Feb 21, 2012 6:55 am

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This would be a highly unusual and limited definition of bacterial resistance. Note that although the precise mechanisms of chlorine resistance are still unknown, at least in one case a connection with multidrug resistance was found. This, in turn, may be indicative of the involvement of efflux transporters.
Note that differences in resistances of an order of magnitude have already been described for chlorine resistance. Also note that your initial claim was that no bacterial resistance mechanisms should exist.

Quote:
I will disbelieve your claim that some bacteria are chlorine resistant.


However, I believe the issue is more or less cleared up now.


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Rory
Post  Post subject: Re: welcome to the post-antibiotics world  |  Posted: Wed Jan 07, 2015 10:26 pm
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25 new antibiotics discovered, one of which is effective against MRSA (in mice). I haven't read the details yet but it looks promising.

http://m.bbc.co.uk/news/health-30657486

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