Thread: Drug resistant bacteria

I understand the basic principle behind the development of drug resistant strains as a result of using antibiotics. A person gets infection, takes the antibiotics, all the drug susceptible bacteria die and we are left with the drug resistant ones. The drug resistant ones are then free to do reproduce creating a new strain. Basically evolution on steroids.

My question is - do the antibiotics in any way cause the mutation of the drug susceptible bacteria into drug resistant ones? Or is it all just survival of the fittest?

Survival of the fittest, though there is evidence that rates of mutation may be up regulated by some bacteria when they are under stress. I don't know of any examples of antibiotics activating hypermutation though.

Consider this scenario. Someone is supposed to take an antibiotic course for 10 days. After 5 days they stop because they feel better. Suppose that the bacteria involved have a range of susceptibility to the antibiotic. The ones most likely to die from the drug do die. The ones less likely to die do not.

If the surviving bacteria might all have died from a full course, is it possible that the final population although subdued might be more likely to produce a drug resistant strain in the future. The genes for drug susceptibility get weeded out in this way.

I'm not sure. So I'm asking.

Originally Posted by hokie

Consider this scenario. Someone is supposed to take an antibiotic course for 10 days. After 5 days they stop because they feel better. Suppose that the bacteria involved have a range of susceptibility to the antibiotic. The ones most likely to die from the drug do die. The ones less likely to die do not.

If the surviving bacteria might all have died from a full course, is it possible that the final population although subdued might be more likely to produce a drug resistant strain in the future. The genes for drug susceptibility get weeded out in this way.

I'm not sure. So I'm asking.

That's essentially how it works, usually if there is good drug adherence you don't get resistance because the immune system can cover for what the drug doesn't kill. But, if you take the drug sporadically you increase the chance of resistance.

Also, ending the course allows the resistant bacteria to multiply and cause real problems - initially there are very few of them, which is why symptoms disappear.