Antibiotics | Resistance Genes | Gene Products | Mechanisms of Resistance |
β-Lactams | blaZ | β-Lactamase | Enzymatic hydrolysis of β-lactam nucleus |
mecA | PBP2a | Reduced affinity for PBP | |
Glycopeptides | GISA: unknown | Altered peptidoglycan | Trapping of vancomycin in the cell wall |
| VRSA: vanA | D-Ala-D-Lac | Synthesis of dipeptide with reduced affinity for vancomycin |
Quinolones | parC | ParC (or GrlA) component of topoisomerase IV | Mutations in the QRDR region, reducing the affinity of enzyme-DNA complex for quinolones |
gyrA or gyrB | GyrA or GyrB components of gyrase |
| |
Aminoglycosides (e.g., gentamycin) | Aminoglycoside-modifying enzymes (eg, aac, aph) | Acetyltransferase, phosphotransferase | Acetylating and/or phosphorylating enzymes modify aminoglycosides |
Trimethoprim-sulfamethoxazole (TMP-SMZ) | Sulfonamide: sulA | Dihydropteroate synthase | Overproduction of p-aminobenzoic acid by the enzyme |
TMP: dfrB | DHFR | Reduced affinity for DHFR | |
Tetracyclines | Tetracycline, doxycycline and minocycline: tetM | Ribosome protection protein | Binding to the ribosome and chasing the drug from its binding site |
Tetracycline: tetK | Efflux protein | Efflux pump | |
Erythromycin | msrA | Efflux protein | Efflux pump |
erm (A, C) | Ribosomal methylase (constitutive or inducible) | Alteration of 23S rRNA | |
Clindamycin | erm (A, C) | Ribosomal methylase (constitutive or inducible) | Alteration of 23S rRNA |
Linezolid | cfr | Ribosomal methyltransferase | Methylation of the 23S rRNA that interferes with ribosomal binding |
Daptomycin | mprF | Lysylphosphatidylglycerol synthetase (LPG) synthetase | Increasing: synthesis of total LPG, outer LPG translocation and positive net charges on cell membrane |