Interactions Among Cell Wall Inhibitors and Protein Synthesis Inhibitors

[sunealoneal]

I noticed when studying that some beta-lactams like monobactams and vancomycin are synergistic with aminoglycosides and other cell wall inhibitors like penicillins are antagonistic.

From what I understand, the antagonism is because when protein inhibitors like aminoglycosides are used, less new peptides are generated, making cell wall inhibitors like the penicillins moot. This is because penicillins prevent crosslinking between **new** and old peptides. If there are no new peptides, the cell wall inhibitors cannot function.

Monobactams work the same way as penicillins due to them both being beta-lactams, yet work synergistically by weakening the call wall and increasing penetrane for the aminoglycosides. So what am I missing? Why can one combination work but not the other?

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[DermViser]

I noticed when studying that some beta-lactams like monobactams and vancomycin are synergistic with aminoglycosides and other cell wall inhibitors like penicillins are antagonistic.

From what I understand, the antagonism is because when protein inhibitors like aminoglycosides are used, less new peptides are generated, making cell wall inhibitors like the penicillins moot. This is because penicillins prevent crosslinking between **new** and old peptides. If there are no new peptides, the cell wall inhibitors cannot function.

Monobactams work the same way as penicillins due to them both being beta-lactams, yet work synergistically by weakening the call wall and increasing penetrane for the aminoglycosides. So what am I missing? Why can one combination work but not the other?

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC429135/

"Synergy with penicillin-aminoglycoside combinations was found in two strains..."

 

[sunealoneal]

Interesting. When I searched before posting, I came across this:

http://www.ncbi.nlm.nih.gov/m/pubmed/7174538/

I suppose that means there isn't a simple explanation.

 

[DermViser]

Interesting. When I searched before posting, I came across this:

http://www.ncbi.nlm.nih.gov/m/pubmed/7174538/

I suppose that means there isn't a simple explanation.

You'll realize quite quickly that a lot of the rules and adages that are taught in basic science coursework doesn't necessarily match up with real-life clinical medicine. If it did, medicine would be so much easier.