What changes can occur in the cell wall of a bacteria for it to survive a β-lactam antibiotic?

I think that because a bacteria possesses peptidoglycan in its cell wall, they are β-lactam sensitive, hence the only way it could survive a β-lactam treatment would be the presence of a resistance gene caused by a mutation. I can't think of another way.

Any ideas?

  • $\begingroup$ There can be infinite possibilities actually. One can even say that the bacteria can evolve to make the cell wall made of a different material. This question is broad. Please add details to narrow down the question or else it will be closed. $\endgroup$ – WYSIWYG Feb 3 '16 at 4:50
  • $\begingroup$ There's no need to add more details, this question is the basis of a question I got from a General Microbiology exam a few years ago, now I'm studying for my exam. Moreover, the only detail was given in the exame was that the bacteria had peptidoglycan in its cell wall, and it survived a β-lactam treatment, then what changes may have occur in its cell wall? $\endgroup$ – Paco Pacotilla Feb 3 '16 at 5:01
  • $\begingroup$ This question formulated as it is, shows that I've thinked of it, I've developed my own theory. Moreover, I've read a lot the Brock's book and still I don't know the full answer to this question. I've seen lots of questions don't showing even a little bit of own work, and still with positive reviews. I see absolutely no reason for this question to be closed. $\endgroup$ – Paco Pacotilla Feb 3 '16 at 5:06
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    $\begingroup$ Just because it was asked in an exam doesn't make it a precise question. The possibility of a resistance gene, as you mentioned in your answer is one of the obvious reasons and I am pretty sure the examiner wants this only. However, as I said, there can be several reasons. Penicillin-binding proteins can lose their affinity to penicillin or cell wall composition itself might change such that penicillin has no effect. Bacteria can also express efflux pumps to remove ampicillin or simply the bacteria may remain as protoplast and survive the treatment. $\endgroup$ – WYSIWYG Feb 3 '16 at 5:15
  • $\begingroup$ I am not saying that this is a bad question. Just saying that there can be a lot of possibilities and hence the examiner who asked this question should have asked a better question. One way to make the question precise is to ask what are the documented mechanisms which let the bacteria survive the antibiotic treatment. Then we can at least not think of the myriad of theoretical possibilities. $\endgroup$ – WYSIWYG Feb 3 '16 at 5:19

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