Antimicrobials - Inhibitors of Protein Synthesis Flashcards
True or False: Antimicrobial Inhibitors of Protein Synthesis are mainly Bacteriostatic.
True
MOA of Tetracylcines
Reversibly bind 30S subunit of ribosome, preventing attachment of aminoacyl tRNA; enter cell via passive diffusion and active transport and concentrate intracellularly
Tetracycline mechanisms of resistance
Enzymatic inactivation, production of proteins that interfere with binding to ribosome, impaired influx or increased efflux
Used to treat Syphilis in Penicillin allergic patients
Tetracyclines
Part of combination therapy for H.pylori, malaria prophylaxis and treatment, and treatment of plague, brucellosis, and tularemia
Tetracyclines
Absorption decreased by divalent cations and milk
Tetracyclines
Tetracycline that reaches high concentrations in all secretions
Minocycline
Lipid soluble Tetracycline for STDs and Prostatitis
Minocycline; give parenterally
AE of Tetracyclines
Hypoplasia and discoloration of teeth, stunting of growth, Photosensitivity
Contraindications of Tetracyclines
Category D, children under 8 yoa
Glycylcycline with Black Box warning –> last resort treatment
Tigecycline
Susceptible to Proteus and Pseudomonas efflux pumps
Tigecycline
MOA Tigecycline
Binds 30S ribosomal subunit
Contraindications of Tigecycline
Pregnancy, children under 8 yoa
Contraindications of Aminoglycosides
Teratogenic (Category D), Myasthenia Gravis
AE of Aminoglycosides
Nephrotoxic, Neuromuscular blockade, Ototoxic, and Teratogenic
Mechanisms of Resistance to Aminoglycosides
Modification/Inactivation of drug, decreased accumulation, modification of 30S binding site
How often are Aminoglycosides given, and why?
Once daily; Post-antibiotic effect + concentration- dependent killing
Which drugs do time-dependent killing?
Penicillins and Cephalosporins
Lactulose MOA
Nonabsorbable disaccharide degraded by intestinal bacteria to form Lactic Acid; favors NH4+ formation –> acidifying gut lumen and reducing plasma ammonium concentrations
AE of Lactulose
Osmotic diarrhea, flatulence, abdominal cramping
MOA of Macrolides
Reversibly bind 23S rRNA of 50S ribosomal subunit, inhibiting translocation
Macrolide resistance mechanisms
Production of esterase to hydrolyze drugs (enterobacteriacea), modification of ribosomal binding site, decreased membrane permeability, increased efflux
Similar binding site to Chloramphenicol and Clindamycin
Macrolides
Macrolides with CYP450 inhibition
Erythromycin, Clarithromycin, Telithromycyin
Causes Gray baby syndrome (cyanosis)
Chloramphenicol
Inhibits CYP3A4 and CYP2C9
Chloramphenicol
AE: inhibits mitochondrial ribosomes to cause reversible bone marrow suppression or Aplastic Anemia
Chloramphenicol
Active against VRE and used topically for eye infections
Chloramphenicol
Resistance mechanisms of Chloramphenicol
Chloramphenicol acetyltransferase inactivates the drug, altered permeability
Treatment for Toxoplasmosis of the brain
Clindamycin + Pyrimethamine
Alternative treatment for PCP
Clindamycin + Primaquine
Endocarditis prophylaxis when allergic to Penicillin
Clindamycin
AE: potentially fatal C. difficile infection (pseudomembranous colitis)
Clindamycin
Good penetration into abscesses and bone
Clindamycin
Has cross resistance with Macrolides
Clindamycin
Resistance mechanisms of Clindamycin
Receptor modification or mutation, enzymatic inactivation of drug
Acts a weak reversible MAOI
Linezolid
Bacteriostatic, but bactericidal against Streptococcus and C. perfringens
Linezolid
Long post-antibiotic effect
Streptogramins
Inhibits CYP3A4 and penetrates macs and PMNs
Streptogramins
Inhibits formation of 70S complex
Linezolid
AE: mild bone marrow suppression, optic and peripheral neuropathy, lactic acidosis
Linezolid
MOA: Binds and inhibits RNA polymerase
Fidaxomicin
Indications of Fidaxomicin
C.difficile colitis in adults
Contraindications of Fidaxomicin
Under 18 yoa
What are the Streptogramins?
Dalfopristin and Quinupristin
Alternative treatments for Hepatic Encephalopathy
Oral Vancomycin, Metronidazole, or Rifaximin