Antibiotic Overview
| Antibiotic type | Antibiotic class | Mechanism | Cidal? | Example | Resistance |
| cell wall synthesis | Beta lactam | inhibits transpeptidases & carboxy peptidases by binding PBPs | Cidal | penicillin, cephalosporin, | enzymatically inactivated by Beta-lactamases |
| carbapenems, monobactams, cephamycin | Pseudomonas & Acinetobacter have CW that are intrinsically resistant | ||||
| Glycopeptides, antimicrobials | blocks transfer of NAG-NAMA subunits to growing peptidoglycan in Gram + bacteria | Cidal | vancomycin, teicoplanin | Gram – are resistant b/c can’t penetrate CW | |
| resistant Enterococci have transposon–> ends with D-Ala-D-lactate not D-Ala-D-Ala | |||||
| Cycloserine | structural analog of D-Ala ligase in bacterial cytoplasm | cidal | |||
| Protein synthesis inhibitor | Aminoglycosides | binds 30S subunit to prevent formation of initiation complex | streptomycin, gentamicin, amikacin | Adenylation of OH group by nucleotidyltransferase, Phosphorylation of OH | |
| by phosphotransferase Acetylation of NH2 by acetyl transferase | |||||
| mutations present that alter target Not effective against anaerobic bacteria | |||||
| Tetracycline | attach to 30S ribosome & prevents binding of aminoacyl tRNA | static | major mech. Is to decrease permeability by an energy depend efflux through a pump protein, encoded by a plasmid | ||
| Tet binding protein from plasmid prevents from binding to ribosome | |||||
| Macrolides & Lincosamide | Bind 50S ribosome and prevents translocation | static | m= erythromycin l=clindamycin | Altered target due to methylation of 2 adenine nucleotides of 23S rRNA, plasmid encoded | |
| Chloramphenizol | inhibits peptidyl transferase enzyme that links AA in the growing chain | static | acetylation of OH on chlorampehnicol acetyltransferase decreases permeability for some Gram | ||
| Fusidic acid | steroid like, inhibits protein syn. forms stable complex w/ elongation factor G, GDP & ribosome | active against Gram + (used for staph infections) | chromosomal mutations in gene for EFG | ||
| Metabolic inhibitors | Sulfanamides | Inhibits 1st enzyme in folic acid synthesis | static | syn. Of new dihydropteroate synthetase w/ low affinity for sulfonamides, plasmid encoded | |
| trimethoprim | inhibits dihydrofolate reductase which is needed for the reduction of folate | static | syn. Of new dihydrofolate reductase that can’t bind trimethoprim, plasmid encoded | ||
| Nucleic Acid biosynthesis inhibitors | Quinolones (synthetic) | Block DNA gyrase inhibiting DNA replication, specific for bacterial gyrase | cidal | fluoroquindones ciprofloxin, norfloxacin | chromosomal mutation in gyrA gene which makes subunit of DNA gyrase, no plasmid encoded resistance |
| Rifampicin | inhibits RNA polymerase and stops transcription of mRNA, specific for bacterial gyrase | cidal | Chromosomal mutation in Beta subunit of RNA polymerase | ||
| Affect Membrane Permeability | Polymixins | cyclic polypeptide that disrupts phospholipid structure of cytoplasmic mem | cidal | not specific for bacteria – used topically |
Tags: Adenylation, Aminoglycosides, antimicrobials, Beta lactam, Beta-lactamases, Chloramphenizol, chromosomal mutation, dihydrofolate, Fusidic acid, Glycopeptides, peptidases, phospholipid, Tetracycline
