antibioticsbooks

Aminopenicillins
Agents: amoxicillin, ampicillin
Though the antistaphylococcal penicillins improve
on the Gram-positive coverage of natural penicillins,
they do not add to their Gram-negative coverage.
Aminopenicillins are more water-soluble
and pass through porin channels in the cell wall
of some Gram-negative organisms. However, they
are susceptible to beta-lactamases, and resistance
to them has become fairly common in many
regions of the world. Aminopenicillins are rarely
active against staphylococci, because these almost
always produce penicillinases. Also, remember
that these drugs do not have useful activity against
Pseudomonas aeruginosa.
Mechanism of Action
All beta-lactams inhibit cross-linking of peptidoglycan
in the cell wall, leading to autolysis and cell
death.
Spectrum
Good: streptococci, enterococci
Moderate: enteric GNRs, Haemophilus
Poor: staphylococci, anaerobes, Pseudomonas
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