Antibiotics Flashcards
Fosfomycin
Cell wall inhibitor - non-Beta-lactam. Blocks PDG synthesis.
Broad spectrum
Use: single dose for uncomplicated UTI (E. coli & faecalis). Resistance develops with multiple doses.
D-cycloserine
Cell wall inhibitor - non-beta-lactam. Blocks PDG synthesis.
Broad spectrum
Oral, good CNS penetration, active form in urine.
Use: 2nd line in M. tuberculosis treatment.
Toxicity: serious CNS SE, dose related, reversible.
Bacitracin
Cell wall inhibitor - non-beta-lactam. Blocks PDG synthesis.
Narrow spectrum (Gram (+), Neisseria, T. Pallidum)
Uses: Topical only. Skin & eye infections. Combine w/ Polymyxin B (membrane inhibitor)
AE: Nephrotoxicity
Vancomycin
Cell wall inhibitor - non-beta-lactam. Blocks PDG x-linking.
Narrow spectrum: Gram (+)
Use: serious Gram (+) infections, MRSA, S. pneumoniae. Synergistic with Aminoglycosides.
Rapid bactericidal for dividing cells - except Enterococci.
IV administration; slowly.
Toxicity: Red Man Syndrome: quick administration - histamine release. Ototoxic, nephrotoxic.
Resistance: VRE, VRSA
Penicillin G (Pen G)
Cell wall inhibitor - Beta-lactam. Bactericidal.
Acid labile, parenteral administration; IM.
Repository forms (Procaine & Benzathine) are longer release than IM.
Use: Gram (+). Non-penicillinase producing microbes.
AE: allergies, Stevens-Johnson Syndrome (erythema, rashing, edema, can be deadly)
Penicillin V (Pen V)
Cell wall inhibitor - Beta-lactam. Bactericidal.
Acid stabile. Oral administration (65% absorption vs 30% Pen G)
Use: Gram (+). Non-penicillinase producing microbes.
AE: allergies, Stevens-Johnson Syndrome (erythema, rashing, edema, can be deadly)
Oxacillin
Cell wall inhibitor - Beta-lactam. Bactericidal.
Penicillinase-resistant. Anti-staphylococcal.
Use: Staph, Strept. Not good against MRSA (PBP with lower affinity for drug)
AE: hepatitis at high doses.
Amoxicillin
Cell wall inhibitor: Beta-lactam - Extended spectrum penicillin. Bactericidal. Destroyed by beta-lactamase.
Acid stable, oral, not affected by food
Use: Gram - bacilli, non-lactamase producing. Mixed infections. Prophylaxis for endocarditis
Carbenicillin
Cell wall inhibitor: Beta-lactam - Extended spectrum penicillin. Bactericidal. Carboxypenicillin.
IV - serious systemic infection. Pseudomonas, Klebsiella
Piperacillin
Cell wall inhibitor: Beta-lactam - Extended spectrum penicillin. Bactericidal. Ureidopenicillin.
IV.
Use: serious systemic infection. Pseudomonas, Klebsiella
Beta-lactamase inhibitor
Clavulanic Acid, Sulbactam.
No Abx activity. Analogs of the drugs. Bind to Beta-lactamase - suicide inhibitors.
Synergistic with extended spectrum penicillins.
Imipenem
Carbapenem. Beta-lactam.
Broadest activity of all B-lactam drugs. Penetrate outer membrane of Gram - bacteria
IV, renal metabolism and inactivation. W/ Cilastatin, inhibits metabolism of Imipenem.
Use: second line for serious infections
Not useful for MRSA, VRE. May induce B-lactamase expression (antagonistic to pen, ceph)
Aztreonam
Beta-lactam. Monobactam.
Binds PBP, relatively resistant to B-lactamase.
No significant cross reactivity with pen***
Use: limited to Gram -, Pseudomonas
Not anaerobes, Gram +
Daptomycin
Cell membrane agent - membrane depolarization
IV administration.
Similar to Vancomycin, but can treat MRSA, VRE
Tetracycline, Doxycycline, Minocycline
Tetracyclines
Inhibit 30s subunit.
Antagonizes penicillin. Decreased absorption with cations, increased pH.
BROAD spectrum, superinfetcion.
Use: Acne, Rickettsia, good CNA penetration
Discoloration of teeth
Tigecycline
Derivative of minocycline
Inhibitor of 30s subunit. Binds with higher affinity than tetra cyclines.
Use: some MRSA, tet-resistant
Gentamicin
Aminoglycosides
Protein Synthesis Inhibitor (30s) Irreversible
Only ones that are bactericidal
Significant PAE (post antibiotic effect)
Use: Gram - bacteria. Combination with penicllin, vancomycin (help get aminoglycosides into cells)
Slow resistance.
Not well absorbed - IV, or IM only. Poorly distributed. Concentrate in inner ear (irreversible), renal cortex.
Spectinomycin
Protein Synthesis Inhibitor (30s)
Structurally related to aminoglycosides.
Bacteriostatic.
Use: mostly Gram -; ***anti-biotic resistant gonorrhea, MRSA
Azithromycin, Clarithromycin, Erythromycin***
Macrolides
Protein Synthesis Inhibitor - bind irreversibly to 50s subunit.
Bacteriostatic. High doses, alkaline pH.
Combine competitively to same spot as other drugs
Narrow spectrum
Use: Gram +, clarithro- azithro- more effective against anaerobe. Alternative to Penicillin
Resistance: rapid. Cross resistance with many other protein synthesis inhibitors. (MLS-type b resistance: methylases modify bacterial ribosome, unable to bind drug)
Erythromycin is not acid stable.
Wide distribution: even go to abscesses. Poor penetration to CNS.
AE: GI effects*, hepatotoxicity, anorexia
Azithromycin: unique, has no interaction with Cyp450
Telithromycin
Ketolide
Protein Synthesis Inhibitor. Derivative of Erythromycin. Bacteriostatic. Binds 50s subunit at 2 sites. Reduced resistance.
Use: community acquired respiratory tract infection.
AE: exacerbation of myasthenia gravis
Chloramphenicol
Protein Synthesis Inhibitor - reversibly to 50s, near clindamycin and macrolides
Bacteriostatic. Oral
Use: Broad spectrum. Anaerobic, gram -
Wide distribution,
AE: Resistance (gram -, staph. aureus). Gray Baby Syndrome … infants cannot metabolize drug.
Hepatic metabolism Cyp450, prolongs half-life
Synercid = Quinupristin + Dalfopristin
Streptogramin
Protein Synthesis Inhibitor - 50s. Combination makes them bactericidal.
Use: MRSA, VRE (gram +)
Linezolid
Binds to unique site of ribosome - 23s. No cross reaction.
Bacteriostatic
Use: MRSA, VRE
Clindamycin
Lincosamide
Binds 50s subunit. MLS type b resistance
Wide distribution, bone included.
Use: osteomyelitis, abscesses, MRSA, severe Group A
Mupirocin
Topical for use in treating impetigo from MRSA
