Potential Cure For Antibiotic Resistant Infections

kpw10 writes to let us know about research to be published this week that offers hope in the battle against multi-drug-resistant bacteria. "Researchers at the University of North Carolina at Chapel Hill have discovered that two drugs used to treat bone loss in old folks can both kill and short-circuit the 'sex life' of antibiotic-resistant bacteria blamed for nearly 100,000 hospital deaths across the country each year."

Existing drugs are GOOD things

[Slicebo]

It's always good to see existing drugs being used in new ways, because it shortens the amount of time it takes to get the treatment to market.

Re:Unnatural Selection

[TheMohel]

Always a concern, but the trend in medicine over the past decade or so has been to reduce the number of times we prescribe, even as we increase both the dose and duration of care when we do pull the trigger. Antibiotic resistance has been strongly linked to inadequate dosing (killing only the susceptible bugs, while letting the borderline-resistant clones reinforce themselves), as well as to courses too short or patient noncompliance.

Patients are part of the problem too, since there is a tendency (cultural in some cases, personal in others) to demand that a doctor "do something" to fix the problem. Antibiotics were perceived for a long time as something harmless to give in those circumstances, but that perception is fading fast. If anything, the trend now is to err on the side of letting things play out a little more to see if antibiotic therapy is really needed.

This has also caused physicians to have to explain the situation better. I know for myself that when I am explaining to a suspicious parent the reason that I'm not going to give their child an antibiotic for their viral infection, I don't waste a lot of time explaining resistance. If they already understand resistance, they're not asking for antibiotics. If they don't, it just sounds like I'm making things up. I focus instead on side effects and cost, and my typical (true) statement is "about all I can do with antibiotics would be to give your child diarrhea to go with her cold." This is surprisingly effective, especially in the parents of non-potty-trained toddlers.

None of which stops me from pulling out the stops when I'm faced with a septic kid or a real infection that needs to be nuked. In those cases, though, I'm very careful to make sure that the regimen I use is appropriate, considering the resistance patterns and the risk of making them worse.

Now if we could only get the idiots who lace animal feed with antibiotics to do the same. Ever wonder where resistant strains start? Hint: it ain't just in the hospitals.

Re:Unnatural Selection

[Attila Dimedici]

I hate to have to tell you this, but fewer people get sick and die from the "superbugs" than died from their predecessors. Despite what you were taught or at least led to believe, as a general rule, antibiotic resistant bacteria are not "stronger" than the non-antibiotic resistant versions. That is why you very rarely hear of someone getting infected with antibiotic resistant bacteria outside of a hospital. Antibiotic resistant bacteria are at a significant competitive disadvantage when no antibiotics are present. Many people are not aware disease causing bacteria spend most of their existence not causing illness (for various reasons), in these settings the non antibiotic resistant bacteria generally completely overrun the antibiotic resistant bacteria.

Don't trivialise this

[CrankyOldBastard]

It's easy to be a sceptic and ask about 'and what about when the bugs become resistant to this'. As a person who had his life ruined by MRSA, I know too well the impact these types of infection have on individuals and families. Anything that can extend the reach of antibiotics (particularly the less toxic ones - I was only 2 or 3 days off being killed by the antibiotic that beat my infection) and decrease the chance of resistance is a good thing.

Hopefully this won't be used promiscuously, and I hope they'll work out the interactions with other treatments, as quite often treatment is multi-modal.

I wouldn't wish what I go through due to MRSA on anyone (except my stepfather, but that's another story altogether.

Evolutionary Cost

[Kashra]

Undoubtedly, bacteria will learn to "get around" these drugs, just as they have traditional antibiotics. But don't look at evolution as a magical process -- everything comes at a cost. Drugs attack essential pieces of a bug's life machinery, and evolving around them is often difficult and reduces the survivability of those bugs, compared to non-resistant strains (unless, of course, they are being selected by the drug in question).

You can expect, the moment we stop using beta-lactam antibiotics, resistance to them will disappear from the population. So combining multiple vectors of antibiotics is useful, both in eliminating the bacteria (for now) and in making them weaker (in the future).

In an ideal situation, multiple drugs would attack systems that are so critical that evolving around them would make the bacteria so weak as to be unable to defend against the host immune system.

Re:Unnatural Selection

[Attila Dimedici]

Most (if not all) antibiotic resistant strains of bacteria accomplish this resistance by disabling the protein which the antibiotic attacks. The reason they had said protein in the first place was because it offered a significant competitive advantage. To be precise, the protein in question in most cases has to do with carrying chemicals across the cell membrane. The bacteria are significantly less efficient at transferring chemicals across the cell membrane without the protein that they have deactivated to be resistant to antibiotics. It is sort of like if you avoid being exposed to poison by not opening your mouth, the poison wouldn't get in, but it would be harder to eat.

Re:Unnatural Selection

[TheMohel]

Yep. I've got patients who do the same (I live in an area where we have a lot of Hispanic immigrants, legal and otherwise). Nothing I can do about it except to talk with them, which I do. I try to encourage them to be reasonable and to take an entire course when they start one (nothing's worse than an occasional antibiotic pill). I have mixed success, but I don't expect perfection and I think my attitude helps the situation. I do get a lot of "do you suggest I start this" kinds of calls and questions and I treat those calls as victories.

This gets me into the whole doctor-as-gatekeeper-for-pills thing that drives me nuts. I challenge colleagues once in a while: in an environment where all medications were available at retail, could they still justify their fees? Could they market themselves well enough to avoid starvation? I think I could, because of the kind of medicine I practice (and because I can sometimes go a dozen patients between giving a prescription), but it's definitely something honest physicians should be asking themselves.

In the no-Rx-required environment, though, there's no question that resistance emerges rapidly. Fortunately, the antibiotics available in Mexico are a small subset of the ones we use here, and most of the ones that patients can buy OTC have broad therapeutic indices (overdose doesn't hurt you much) and are from antibiotic classes (penicillins, macrolides) where we have later-generation alternatives that avoid the common resistances. It's a fluid situation, though, and one that has infectious disease specialists always a little on edge.

Re:Unnatural Selection

[TheMohel]

But someone pointed out what may be obvious, which is that after the full regiment there are going to be few enough of these bacteria left that the human immune system can finish the job of wiping them out completely, leaving no antibiotic-resistant bacteria at all. Is this accurate?

In essence, yes. In fact, people who have immune deficiencies are particularly likely to develop resistant bugs, and we suspect that at least part of the problem is that the immune system can't quite finish the job.

Re:You missed the obvious

[cin62]

Bacteria can take up "free" DNA that's somewhere in the environment (possibly a residue of a dead bacteria). So basically the resistant bacteria does not need to be alive to pass on the resistance genes. http://en.wikipedia.org/wiki/Transformation_(genet ics) [wikipedia.org]