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62 Cards in this Set
- Front
- Back
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What is the primary target of gram (-) bacteria?
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The outer membrane. Can lead to disruption of cytoplasmic membrane->Loss of osmotic stability & unable to carry out metabolic fcns
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What are polymyxins?
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Polypeptide antibiotics w/ signif toxicity, designated A-E (only B & E used colistin & colistimethate).
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What is mech of polymeyxins?
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Displace divalent cations from phospholipid->membrane disruption]
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What are the important charac of polymyxins?
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Most active against gram neg, low resistance, & active against non-growing cells
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Why not use polymixins all the time to treat Gram (-) bacteria?
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Relatively toxic (nephrotoxic & neurotoxic) so restricted to topical admin (often combined w/ bacitracin to inc activity against gram (-). Systemic use restricted to serious infection (salvage therapy)
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Daptomycin location of action?
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Cell membrane
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Daptomycin functional mech?
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Depolarize cytoplasmic membrane; used in MRSA &VRSA
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Daptomycin G+ or G-?
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G+
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Daptoycin static or cidal?
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cidal
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Daptomycin resistance?
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Rare. Mech unknown; accumulation of point mutations in diff genes. From prolonged exposure or naïve patients. Vancomycin may select for strain resistant to dap
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What membrane-active antobiotics are used as anti-fungals?
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Polyene & azole antiboitics
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What is mech of polyene antiboitics?
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Bind sterol membrane->pore formation (eg Amphotericin B systemically & Nystatin topical)
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What is mech for azole antibiotics?
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Inhibit sterol synthesis *largest group of antifungals (eg flucinazole & ketoconazole)
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What are beta lactams?
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Largest class of cell wall inhibitors & largest single class of antibiotics
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What are the common properties of beta lactams?
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4 member ring, target PBP, inhibit transglycosylation & transpeptidation (impairs cell division & causes cell lysis), bactericidal, G-
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Beta lactam intrinsic resistance?
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Outer membrane passage requires porins
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Beta lactam acquired resistance?
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Production of beta-lacatamase (plasmid encoded)->degrades 4-ring, can confer methicillin resistance
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What are beta lactamase inhibitors?
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Suicide inhibitors of beta lactamase. Little antibacterial activity. Can be specific of less specific
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What combination makes Unasyn?
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Ampicillin & sulbactam
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What combination makes Augmentin?
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Amoxicillin & clavulante
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What combination makes Timentin?
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Ticarcillin & clavulante
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What combination makes Zosyn?
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Piperacillin & tazobactam
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Penicillin G location of action?
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Cell Wall
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Penicillin G functional mech?
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Binds PBP, acid sensitivie & poorly absorbed
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Penicillin G G+ or G-?
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G+
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Penicillin G static or cidal?
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cidal
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Penicillin G resistance?
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beta lactamase
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Penicillin V location of action?
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Cell Wall
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Penicillin V functional mech?
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Binds PBP, acid stable, oral admin
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Penicillin V G+ or G-?
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G+
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Penicillin V static or cidal?
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cidal
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Penicillin V resistance?
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beta lactamase
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What are the extended spectrum penicillins?
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Aminopenicillins (Amipicillin & Amoxicillin), Carboxypenicillin (Carbenicillin & Ticarcillin), Ureidopenicillin (Pipericillin)
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What are the charac of extended spectrum penicillins?
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G- & more resistant to beta lactamases
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What are 1st generation cephalosporins/cephamycins? Charac?
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Cefazolin & Cephalothin. Narrow spectrum & G+
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What are 2nd generation cephalosporins/cephamycins? Charac?
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Cefaclor & Cefonicid. Expanded spectrum. G+ & anaerobes
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What are 3rd generation cephalosporins/cephamycins? Charac?
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Cefotaxime. Broad spectrum. G-
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What are 4th generation cephalosporins/cephamycins? Charac?
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Cefepime. Extended spectrum. Resistan to beta-lactamase
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Methacillin location of action?
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Cell wall
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Methacillin functional mech?
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Binds PBP, acid sensitive, can't be given orally
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Methacillin G+ or G-?
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G+
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Methacillin static or cidal?
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cidal
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Methacillin resistance?
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Chrom encoded mecA gene->PBP2A & PBP2
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What is the difference b/w methacillin & Oxacillin/Nafcillin?
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Oxacillin/Nafcillin is Acid stable & can be absorbed from GI
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What has the broadest spectrum of all beta lactams?
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Carbapenems (Imipenem & Meropenem)
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Monobactams (Aztreonam) functional mech?
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Binds PBP, narrow spectrum
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Monobactams (Aztreonam) G+ or G-?
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Aerobic G-only (less likely to disrupt normal flora
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Vancomycin location of action?
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Cell wall
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Vancomycin functional mech?
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Binds irreversibly to terminal alanines on NAM->inhibits translocation/transpeptidation rxns
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Vancomycin G+ or G-?
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G+ (especially MRSA)
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Vancomycin static or cidal?
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cidal
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Vancomycin resistance?
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Intrinsic: can't pass G- outer membrane. Acquired:Transposon encodeing substitution of D-alanine for D-lactate
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Bacitracin location of action?
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Cell wall
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Bacitracin functional mech?
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Inhibits translocation of peptidoglycan precursors. Toxic->limited to topical (Neosporin)
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Bacitracin G+ or G-?
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G+
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Bacitracin static or cidal?
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cidal
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Fosfomycin location of action?
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Cell Wall
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Fosfomycin functional mech?
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Inhibits formation of cytoplasmic subunits. UTI
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Fosfomycin static or cidal?
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cidal
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Cyclserine location of action?
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Cell Wall
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Cycloserine functional mech?
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Inhibits translocation of & cross linking.Used w/1st line resistant strains. Mycobacteria
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Cycloserine static or cidal?
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cidal
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