Penicillins

A Penicillin molecule looks like a little house with a garage & TV antenna but the garage is very prone to break-ins due to some Bacteria that produce beta lactamase enzymes that breaks beta Lactam ring which makes Penicillins useless such as Pseudomonas, Escherichia coli, Staphylococcus Aureus. As a strategy, manipulate size of R group to become big to stop beta lactamase from attacking beta lactam ring.

Beta Lactam Ring with very large R group anti-staphylococcal Penicillins includes Oxacillin, Nafcillin, Methicillin, Cloxacillin Dicloxacillin. They combat Methicillin Susceptible Staphylococcus Aureus.

Another way to stop Beta lactamase from attacking beta lactam ring is to Set up square shaped decoys that looks like the beta lactam ring called Beta lactamase decoy (or Beta lactamase inhibitors) and combine it with small R group Penicillins for example. Amoxicillin gets combined with Clavulinic acid (which is a beta lactamase decoy) for example augmentin brand. Piperacillin gets combined with Tazobactam (which is a beta lactamase decoy). Ampicillin gets combined with sulbactam (which is beta lactamase decoy) (for example unasyn brand)