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20 Cards in this Set
- Front
- Back
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Streptogramins
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Quinupristin - SGMB
Dalfopristin - SGMA Synercid - Quinupristin/Dalfopristin(30:70) |
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Streptogramins are
Bacteriostatic or Bactericidal? |
Either agent alone is weakly bacteriostatic.
But combination is bactericidal. |
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Streptogramins A and B
MOA |
SGMA - binds 50S (bridges A & P sites); inhibit early stages of elongation
SGMB - binds 50S (same as Mac); blocks "exit" tunnel for building peptides- latter stages |
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Streptogramins
Spectrum of Activity |
Gram (+) cocci
S.pneumoniae, E.faecium, Staphylococci Neisseria (gram (-)) Atypical pneumonia (M.pneumoniae, Legionella, Chlamydia pneumoniae) |
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Streptogramins
Mechanisms of Resistance |
1. MLSB Resistance - target modification: methylation of A2058 in 50S (constitutive or inducible)
2. Expression of Efflux Pumps (inducible or constitutive) 3. Inactivating Enzymes - (acetylate) |
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Streptogramins
ADME |
Administered IV
Hepatic metabolism Primarily excreted in bile |
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Streptogramins
Clinical Use |
Serious infections (e.g. bacteremia) with VRE (faecium)
SSSI due to MRSA |
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Streptogramins
ADRs |
Local Pain/Irritation with IV administration
Myalgias/Arthralgias May increase plasma conc of drugs metab by CYP3A4 |
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Bacitracin
MOA |
Binds to and inhibits dephosphorylation of C55 isoprenyl pyrophosphate (step necessary for transport of cell membrane building block)
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Bacitracin
Bacteriostatic or Bactericidal? |
Bactericidal
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Bacitracin
Spectrum of Activity |
Primarily Gram (+) cocci & baccili
Effective agains a few Gram (-) |
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Bacitracin
Resistance |
Relatively rare as use is primarily via topical preparations
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Bacitracin
ADME |
Poor oral absorption
Primarily Topical (Dermal: Triple Antibiotic Ointment w/Neomycin & Polymysin B) Not stable in cream base Also used in ophthalmic preps |
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Bacitracin
Clinical Uses |
Topical Triple Antibiotic Ointment to treat skin wounds - (surgery or injury), burns
Inkjam, Conjuncitivitis, Corneal ulcers |
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Bacitracin
ADRs |
Topical - allergic contact dermatitis
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Polymyxin B & Colistins
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amphipathic - cationic cyclic peptide & hydrophobic fatty acid (detergent like)
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Polymyxin B & Colistins
MOA |
Bidns via electrostatic forces to LPS on outer membrane, forms pore, leads to cell lysis
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Polymyxin B & Colistins
Bacteriostatic or Bactericidal |
Bactericidal
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Polymyxin B & Colistins
Resistance |
Cross-resistance occurs btwn Polymixin B & colistin
Usually involves altered target (decreased LPS, change in lipid content) |
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Polymyxin B & Colistins
ADME |
Very poor orally - little dermally
Polymyxin B - topical, ophthalmic, & otic Colistin - topical & oral Colistimethate sodium - IV, inhalation |
