Page Contents
OVERVIEW
This page is dedicated to compiling Step 1 study notes for the topic of antibiotic mechanisms of action. This page is likely disorganized as it was made in haste.
PENICILLINS
Mechanism of resistance:
- Beta-lactamase, ESBL
- Mutated PBP
- Mutated porin protein
FIRST GENERATION CEPHALOSPORINS
Examples of drugs:
Cephalexin,
Mechanism of action:
This class of medications interfere with bacterial cell wall synthesis by a mechanisms similar to penicillin. Beta-lactam ring that binds penicillin binding proteins in bacterial cell walls, inhibit peptidoglycan production, and inhibits the transpeptidase cross-linking the cell wall. Less susceptible to penicillinases then penicillins.
QUINOLONES
Examples of drugs:
Mechanism of resistance:
- Mutated DNA gyrase
- Impaired influx/increased efflux
AMINOGLYCOSIDES
Examples:
Mechanism of action:
Interfere witht he aminoacyl binding site on the 30S ribosomal subunit. Causes the cell to misread mRNA, so it becomes unable to perform protien synthesis.
Mechanism of resistance:
- Methylation of the aminoglycoside binding portion of the ribosome (inhibits binding of the drug)
- Aminoglycoside-modifieying enzymes
- Mutated ribosomal subunit protein
- Mutated pro in protein
TETRACYCLINES
Mechanism of resistance:
- Impaired influx/increased efflux
- Inactivated enzyme
RIFAMYCINS
Mechanism of resistance:
- Mutated RNA polymerase
MACROLIDES
Examples of drugs:
Azithromycin, clarithromycin, erythromycin.
Mechanism of action:
Inhibit protein synthesis by blocking translocation. They bind to the 23S rRNA of the 50S ribosomal subunit..
Mechanism of resistance:
- The methylation of 23S rRNA-binding site prevents binding of drug.
Page Updated: 04.15.2017