FA - Micro - Antimicrobials (2016) Flashcards
Carbapenems - Mechanism of imipenem:
- Broad-spectrum, β-lactamase-resistant carbapenem.
- ALWAYS administered with cilastatin (inhibitor of renal dihydropeptidase I) to DECREASE inactivation of drug in renal tubules.
Newer carbapenems include:
- Ertapenem –> LIMITED PSEUDOMONAS coverage.
2. Doripenem.
Carbapenems - Clinical use:
- Gram (+) cocci.
- Gram (-) rods.
- Anaerobes.
Carbapenems - Clinical use limited to …?
Life-threatening infections or after other drugs have failed.
–> Significant side effects.
Meropenem has …?
Decr. risk for SEIZURES and is STABLE to dehydropeptidase I.
Carbapenems - Adverse effects:
- GI distress.
- Skin rash.
- CNS toxicity (seizures).
At high plasma levels.
Vancomycin - Mechanism:
Inhibits cell wall peptidoglycan formation by binding D-ala D-ala portion of cell wall precursors.
Vancomycin - Bacteriostatic/cidal?
Bactericidal against MOST bacteria.
- -> Bacteriostatic against C.difficile.
- -> Not susceptible to beta-lactamases.
Vancomycin - Clinical use:
Gram (+) bugs ONLY –> Serious multidrug-resistant organisms, including:
- MRSA.
- S.epidermidis.
- Sensitive Enterococcus species.
- C.difficile (ORAL dose).
Vancomycin - Adverse effects:
- Well tolerated in general - But NOT trouble free.
- Nephrotoxicity.
- Ototoxicity.
- Thrombophlebitis.
- Diffuse flushing - Red man syndrome (pretreat with antihistamines + slow infusion rate).
Vancomycin - Mechanism of resistance:
Occurs in bacteria via amino acid modification of D-ala D-ala to D-ala D-lac.
Oxazolidinones:
Linezolid.
Linezolid - Mechanism:
- Inhibits protein synthesis by binding to 50S.
2. Prevents formation of the initiation complex.
Linezolid - Clinical use:
Gram (+) species including MRSA + VRE.
Linezolid - Adverse effects:
- Bone marrow suppression (esp. thrombocytopenia).
- Peripheral neuropathy.
- Serotonin syndrome.
Linezolid - Mechanism of resistance:
Point mutation of ribosomal RNA.
Dapsone - Mechanism:
Similar to sulfonamides, but structurally distinct agent.
Dapsone - Clinical use:
- Leprosy (lepromatous and tuberculoid).
2. PCP proph.