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226 Cards in this Set
- Front
- Back
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Name the 5 major classes of beta-lactams.
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Penicillin, Cephalosporin, Cephamycin, Carbapenem, Monobactam
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Name the 5 classes of penicillin-type beta-lactams.
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Aminopenicillin, Carboxypenicillin, Ureidopenicillin, Natural, Penicillinase-resistant
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Which penicillin-type beta-lactams are broad-spectrum antibiotics?
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Aminopenicillin, Carboxypenicillin, Ureidopenicillin
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Are beta-lactams bactericidal or bacteriostatic?
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Bactericidal
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Describe the structure of beta-lactam antibiotics.
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Beta-lactam ring (GluNAc/MurNAc disaccharide chains 10-65 long, w/ peptide crosslinks)
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What is the general method of action that beta-lactams use against bacteria?
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Inhibit Cell Wall Synthesis
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What is the specific action mechanism that beta-lactam antibiotics use against bacteria?
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Bind to PBPs and inhibit cross-linking of peptidoglycan chains, which activates autolysins which in turn degrade the cell wall.
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What are beta-lactams used against?
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gram+ cocci (activity = natural penicillins), some gram- bacilli
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What do beta-lactams encounter resistance from?
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Bacteria with beta-lactamase (serine protease)
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How do you counter resistance to a beta-lactam antibiotic?
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Add a beta-lactamase inhibitor (clavulanic acid, sulbactam, tazobactam, davulanate)
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What are the 4 beta-lactamase inhibitors we were taught by Landolph?
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Clavulanic acid, sulbactam, tazobactam, davulanate
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What are penicillin-type beta-lactams derived from?
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Penicillin chrysogenum mold -> 6-aminopenicillanic acid -> modification
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Name the 8 major classes of antibiotics that act by inhibiting cell wall synthesis.
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Penicillin-type beta-lactams, cephalosporin-type beta-lactams, cephamycin-type beta-lactams, carbapenem-type beta-lactams, monobactam-type beta-lactams, glycopeptides, lipopeptides, polypeptides
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Name 2 examples of aminopenicillin-class penicillin-type beta-lactams.
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Ampicillin, Amoxicillin
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Name 2 examples of carboxypenicillin-class penicillin-type beta-lactams.
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Carbenicillin, Ticarcillin
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Name 1 example of ureidopenicillin-class penicillin-type beta-lactams.
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Piperacillin
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Name the most active antibiotic among the broad-spectrum penicillin-type beta-lactams.
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Piperacillin
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Name the most active anti-beta-lactamase drug cocktail (among beta-lactam penicillin-types).
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Piperacillin / Tazobactam
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Why is Penicillin G only used intravenously?
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It's inactivated by gastric acid.
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What advantage does Penicillin V have over Penicillin G?
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It is more resistant to gastric acid so it can be used orally.
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Penicillin G is also known as...
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Benzylpenicillin
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Benzylpenicillin is also known as...
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Penicillin G
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Penicillin V is also known as...
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Phenoxymethyl Penicillin
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Phenoxymethyl Penicillin is also known as...
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Penicillin V
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Name 2 examples of "natural"-class penicillin-type beta-lactams.
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Penicillin G, Penicillin V
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What are natural-class penicillin-type beta-lactams used against?
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Beta-hemolytic streptococci, meningococci, gram+ anaerobes (in addition to the general beta-lactam activity against gram+ cocci and selected gram- bacilli).
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What do "natural"-class penicillin-type beta-lactams encounter resistance from?
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Staph and gram-negative rods (in addition to the resistance from beta-lactamase carriers faced by beta-lactams in general).
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Name 5 examples of penicillinase-resistant penicillin-type beta-lactams.
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Methicillin, Nafacillin, Oxacillin, Cloxacillin, Dicloxacillin
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What are penicillinase-resistant-class penicillin-type beta-lactams used against?
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Beta-hemolytic streptococci, meningococci, gram+ anaerobes, staphylococci.
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Name 5 examples of 1st generation Cephalosporin-type beta-lactams, and state their spectrum activity.
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Cephalexin, Cephalotin, Cefazolin, Cephapirin, Cephradine
Narrow-spectrum |
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Name the general method of action used by Cephalosporin antibiotics against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Cephamycin antibiotics against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Carbapenem antibiotics against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Monobactam antibiotics against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Vancomycin against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Glycopeptide antibiotics against bacteria.
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Inhibit Cell Wall Synthesis
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What type of beta-lactam is Vancomycin?
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Glycopeptide
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Name the general method of action used by Lipopeptide antibiotics against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Polypeptide antibiotics against bacteria.
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Inhibit Cell Wall Synthesis
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Name a sub-class of Polypeptide antibiotics.
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Polymyxins
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Name the general method of action used by Isoniazid against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Ethionamide against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Ethambutol against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Cycloserine against bacteria.
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Inhibit Cell Wall Synthesis
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Name the general method of action used by Aminoglycoside antibiotics against bacteria.
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Inhibit Protein Synthesis
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Name the general method of action used by Tetracycline antibiotics against bacteria
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Inhibit Protein Synthesis
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Name the general method of action used by Oxazolidnone antibiotics against bacteria.
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Inhibit Protein Synthesis
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Name the general method of action used by Chloramphenicol antibiotics against bacteria.
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Inhibit Protein Synthesis
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Name the general method of action used by Macrolide antibiotics against bacteria.
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Inhibit Protein Synthesis
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Name the general method of action used by Lincosamide antibiotics against bacteria.
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Inhibit Protein Synthesis
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What type of antibiotic is Clindamycin?
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Lincosamide
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Name the general method of action used by Streptogramin antibiotics against bacteria.
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Inhibit Protein Synthesis
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Name the general method of action used by Quinolone antibiotics against bacteria.
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Inhibit DNA/RNA Synthesis
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Name the general method of action used by Rifampin against bacteria.
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Inhibit DNA/RNA Synthesis
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Name the general method of action used by Rifabutin against bacteria.
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Inhibit DNA/RNA Synthesis
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Name the general method of action used by Metronidazole against bacteria.
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Inhibit DNA/RNA Synthesis
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Name the general method of action used by Sulfonamide antibiotics against bacteria.
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Antimetabolite Interference
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Which types of antibiotics target the cell wall of bacteria?
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Beta-lactams (penicillin-type, cephalosporin-type, cephamycin-type, carbapenem-type, monobactam-type), Glycopeptides, Lipopeptides, Polypeptides, Isoniazid, Ethionamide, Ethambutol, Cycloserine
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Which are the 7 types of antibiotics that inhibit protein synthesis?
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Aminoglycosides, Tetracyclines, Oxazolidnones, Chloramphenicols, Macrolides, Lincosamides, Streptogramins
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Which types of antibiotics inhibit DNA/RNA synthesis?
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Quinolones, Rifampin, Rifabutin, Metronidazole
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Which types of antibiotics are antimetabolites?
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Sulfonamides
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What are Narrow-spectrum Cephalosporin antibiotics used against?
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Oxacillin-equivalent activity against gram+ and gram- (E. coli, Klebsilla, Proteus mirabilis)
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What are Expanded-spectrum Cephalosporin antibiotics used against?
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Oxacillin-equivalent activity against gram+. "Improved" activity against gram- (Narrow-spectrum activity plus Enterobacter, Citrobacter, some Proteus)
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What is oxacillin used against?
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Beta-hemolytic streptococci, meningococci, gram+ anaerobes, staphylococci.
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What are Broad-spectrum Cephalosporin antibiotics used against?
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Oxacillin-equivalent activity against gram+. "Improved" gram- activity (Expanded-spectrum activity plus Pseudomonas)
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What are Extended-spectrum Cephalosporin antibiotics used against?
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Oxacillin-equivalent activity against gram+. "Marginally improved" gram- activity (on top of Broad-spectrum activity).
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What advantage do Cephalosporin-type beta-lactams have over Penicillin-type beta-lactams?
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More resistant to beta-lactamase
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Which is wider-spectrum: Penicillin-type beta-lactams or Cephalosporin/Cephamycin-type beta-lactams?
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Cephalosporins and Cephamycins
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What are Cephalosporin antibiotics derived from?
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Cephalosporium mold -> 7- aminocephalosporanic acid -> modifcation
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Name 2 examples of Expanded-spectrum Cephalosporin-type beta-lactams.
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Cefaclor, Cefuroxime
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Name 4 examples of Broad-spectrum Cephalosporin-type beta-lactams.
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Cefixime, Cefotaxime, Ceftriaxone, Ceftazidime
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Name 2 examples of Extended-spectrum Cephalosporin-type beta-lactams.
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Cefepime, Cefpirome
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Name 2 examples of Cephamycin-type beta-lactams.
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Cefotetan, Cefoxitin
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What are Cephamycin-type beta-lactams used against?
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Similar activity to Expanded-spectrum Cephalosporins.
[Oxacillin-equivalent activity against gram+. "Improved" activity against gram- (Enterobacter, Citrobacter, some Proteus)]. |
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What is responsible for Cephamycin-type antibiotics' resistance to beta-lactamase?
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More resistant to beta-lactamase b/c of oxygen displacing sulfur in dihydrothiazine ring
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Are Carbapenem-type beta-lactams broad or narrow spectrum?
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Broad
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Name 3 examples of Carbapenem-type beta-lactams.
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Imipenem, Meropenem, Ertapenem
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What are Carbapenem-type beta-lactams used against?
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All bacteria EXCEPT:
Oxacillin-resistant Staph, most Enterococcus faecium, some gram- bacilli (Burkholderia, Stenotrophomonas, Pseudomonas) |
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What do Carbapenem-type beta-lactams encounter resistance from?
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Oxacillin-resistant Staph, most Enterococcus faecium, some gram- bacilli (Burkholderia, Stenotrophomonas, Pseudomonas)
(in addition to general beta-lactamase-carrying bacteria) |
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Are Monobactam-type beta-lactams broad or narrow spectrum?
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Narrow
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Is Aztreonam broad or narrow spectrum?
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Narrow
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Name 1 example of Monobactam-type beta-lactams.
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Aztreonam
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What is Aztreonam used against?
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Some aerobic gram- bacilli
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What are Monobactam-type beta-lactams used against?
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Some aerobic gram- bacilli
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What do Monobactam-type beta-lactams encounter resistance from?
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Inactive against anaerobes, gram+ cocci
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What does Aztreonam encounter resistance from?
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Inactive against anaerobes, gram+ cocci
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What is the advantage of using narrow-spectrum Aztreonam?
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Advantage: used for selective nuking of bugs w/o disrupting normal flora
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What is the specific action mechanism of Vancomycin against bacteria?
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Interferes w/ D-Ala-D-Ala bridging of peptidoglycans in cell wall of gram+
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What is Vancomycin used against?
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Oxacillin-reistant Staph, Beta-Lactam-resistant gram+
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What does Vancomycin encounter resistance from?
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Enterococcus faecium, Entero. faecalis (vanA, vanB plasmid genes change D-Ala-D-Ala terminus)
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What *used to be* the traditional antibiotic of "last resort?"
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Vancomycin
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What is Vancomycin derived from?
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Streptomyces orientalis -> modification
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Name 1 example of Lipopeptide antibiotics.
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Daptomycin
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What is the structure of Daptomycin?
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Cyclic lipopeptide
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What is the specific action mechanism of Daptomycin against bacteria?
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Irreversibly binds to cytoplasmic membrane: depolarizes it and disrupts ion gradients
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What kind of antibiotic is Daptomycin?
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Lipopeptide
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What is Daptomycin used against?
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Gram+ including drug-resistant Staphylococci, Streptococci, and drug-resistant Enterococci
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What is Daptomycin derived from?
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Streptomyces roseosporus -> (natural)
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Name 1 example of (general-class) Polypeptide antibiotics.
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Bacitracin
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What is Bacitracin named for?
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The patient it was isolated from, Tracy I.!
You probably don't need to know this. But now you know how to say Bacitracin! |
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What is the structure of Bacitracin?
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Cyclic polypeptide mixture
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What is the specific action mechanism of Bacitracin against bacteria?
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Blocks trafficking of peptidoglycan precursors to cell wall by interfering w/ de-phosphorylation and recycling of lipid carrier.
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What is Bacitracin used against?
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Gram+ including Staphylococcus and Group A Streptococcus
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Does Bacitracin work better topically or orally?
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Topically. It doesn't work very well orally.
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What is Bacitracin derived from (other than Tracy?)
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Bacillus licheniformis -> (natural)
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Name 2 examples of Polymyxin-class Polypeptide antibiotics.
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Polymyxin B, Polymyxin E (aka Colistin)
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Describe the structure of Polymyxin-class Polypeptide antibiotics.
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Cyclic polypeptides
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Describe the specific action mechanism used by Polymyxin-class Polypeptide antibiotics against bacteria.
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Insertion into membrane, disrupt LPS and phospholipids, displace Mg/Ca ions, disorganize membrane structure/permeability
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What are Polymyxin-class Polypeptides used against?
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Gram- bacilli
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What are some caveats in using Polymyxin-class Polypeptides?
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Can be "seriously nephrotoxic." Use limited to external treatment for localized infections (otitis, eye and skin infections)
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What are Polymyxin-class Polypeptide antibiotics derived from?
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Bacillus polymyxa
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What is the specific action mechanism used by Isoniazid against bacteria?
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Disrupts cell wall building block synthesis (mycolic acid, fatty acids, hydroxylipids)
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What is Isoniazid used against?
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Mycobacteria, tuberculosis
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What does Isoniazid encounter resistance from?
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Drugs that learn to eat up less antibiotic and alter their target sites
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Describe the specific action mechanism used by Ethionamide against bacteria.
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Blocks mycolic acid synthesis (used for cell wall).
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What is Ethionamide used against?
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Mycobacteria
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What is Ethambutol used against?
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Mycobacteria
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What is Cycloserine used against?
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Mycobacteria
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What are the 4 antibiotics used against Mycobacteria?
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Isoniazid, Ethionamide, Ethambutol, Cycloserine
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What is the specific action mechanism of Ethambutol used against bacteria?
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Blocks synthesis of arabino-galactan in cell wall
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What is the specific action mechanism of Cycloserine used against bacteria?
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Inhibits cell wall synthesis enzymes D-Ala-D-Ala Synthetase and Alanine Racemase
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What is Ethionamide derived from?
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Isoniazid (isonicotinic acid hydrazide) -> modification
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Are Aminoglycosides bactericidal or bacteriostatic?
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Bactericidal
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Describe the structure of Aminoglycoside antibiotics.
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Amino sugars linked by glycosidic bonds to aminocyclitol ring.
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What are the 3 Broad-spectrum Aminoglycoside antibiotics?
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Tobramycin, Gentamycin, Amikacin
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What kind of antibiotic is Streptomycin?
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Aminoglycoside
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What kind of antibiotic is Neomycin?
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Aminoglycoside
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What kind of antibiotic is Kanamycin?
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Aminoglycoside
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What kind of antibiotic is Tobramycin?
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Aminoglycoside
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What kind of antibiotic is Gentamicin?
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Aminoglycoside
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What kind of antibiotic is Sisomicin?
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Aminoglycoside
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What kind of antibiotic is Netilmicin?
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Aminoglycoside
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What is the specific action mechanism used by all Aminoglycoside antibiotics against bacteria?
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Irreversibly binds to 30S ribosomal proteins. Misreads mRNA and triggers premature mRNA release.
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What is Streptomycin used against?
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Enterobacteriaceae, Pseudomonas, Acinetobacter, tuberculosis, tularemia, Streptococci and Enterococci (w/ penicillin)
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What do all Aminoglycosides encounter resistance from?
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Streptococci, Enterococci (mutates ribosomal binding site), anaerobes and Pseudomonas (less antibiotic uptake), any bugs that pump it out or tweak it
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How do you counter resistance to Aminoglycosides?
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Co-administer with a cell wall synthesis inhibitor (penicillin, ampicillin, vancomycin, etc). Enterococcus MUST be killed this way
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What is a toxicity caveat in using Aminoglycosides in humans?
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They are ototoxic! (Remember Laird-Offringa's lecture about mitochondrial ribosomes being similar to bacterial ribosomes?)
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Which Aminoglycoside antibiotic is the least ototoxic? Why does this not matter?
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Netilmicin, but it's not very antibacterial, either
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Which two Aminoglycoside antibiotics are commonly used?
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Tobramycin, Gentamicin
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What are Streptomycin, Neomycin, Kanamycin, and Tobramycin derived from?
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Streptomyces -> ?
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What are Gentamicin and Sisomicin derived from?
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Micromonospora -> ?
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What are Neomycin, Kanamycin, Tobramycin, Gentamicin, Sisomicin and Netilmicin used against?
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Enterobacteriaceae, Pseudomonas, Acinetobacter
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What is Amikacin used against?
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Gram- that are resistant to other aminoglycosides
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Which Aminoglycoside has the best activity?
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Amikacin
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Are Tetracycline antibiotics broad- or narrow-spectrum?
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Broad
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Name 3 examples of Tetracycline antibiotics.
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Tetracycline, Doxycycline, Minocycline
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Are Tetracycline antibiotics bactericidal or bacteriostatic?
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Bacteriostatic
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Which bind irreversibly to the 30S ribosomal subunit in bacteria: Aminoglycosides or Tetracyclines?
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Aminoglycosides
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Which bind reversibly to the 30S ribosomal subunit in bacteria: Aminoglycosides or Tetracyclines?
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Tetracyclines
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What is the specific action mechanism used by Tetracyclines against bacteria?
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Reversibly binds to 30S ribosomal proteins. Blocks incoming tRNAs.
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What are Tetracyclines used against?
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Chlamydia, Mycoplasm, Rickettsia, some other gram+ and gram-
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What do Tetracyclines encounter resistance from?
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Any bug that: lets less antibiotic in, pumps it out, alters ribosomal target site, tweaks antibiotic, or protects 30S ribosome (elongation factor-like proteins). Bacterial resistance also from mutation of membrane pore gene OmpF.
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Are Oxazolidnones broad- or narrow-spectrum antibiotics?
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Narrow
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What kind of antibiotic is Linezolid?
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An Oxazolidnone
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What is one example of an Oxazolidnone antibiotic?
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Linezolid
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What is the specific action mechanism of Linezolid?
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Binds to 50S ribo-unit, interferes with 70S initiation complex formation.
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What is Linezolid used against?
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ALL Staph, Strep, and Enterococci Gram+, including strains resistant to penicillins, vancomycin, and aminoglycoside
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What is Linezolid reserved for?
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Reserved for treating multidrug-resistant Enterococci.
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Which antibiotic do you turn towards to treat multi-drug resistant Enterococci?
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Linezolid
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Why does Linezolid not suffer cross-resistance from other protein inhibitor antibiotics?
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Because of its specificity.
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How is Linezolid's mechanism of action different from other antibiotics that inhibit protein synthesis?
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It blocks translation initiation rather than elongation.
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Name the 6 major classes of antibiotics that block elongation in protein synthesis.
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Aminoglycosides, Tetracyclines, Chloramphenicol, Macrolide, Lincosamide, Streptogramin
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Name the 1 major class of antibiotics that block initiation in protein synthesis.
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Oxazolidnones
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Are Chloramphenicol antibiotics broad- or narrow-spectrum?
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Broad
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Are Chloramphenicol antibiotics bactericidal or bacteriostatic?
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Bacteriostatic
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What is the specific action mechanism of Chloramphenicol antibiotics?
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Reversibly binds to 50S peptidyl transferase. Blocks elongation.
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What are Chloramphenicol antibiotics used against?
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Typhoid fever. Similar to tetracycline (Chlamydia, Mycoplasm, Rickettsia, some other gram+ and gram-)
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What do Chloramphenicol antibiotics encounter resistance from?
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Plasmids coding acetyl-transferase.(tweaks chloramphenicol, cannot bind 50S). Gram- that are less permeable to drug from porin mutations.
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Why were Chloramphenicols not commonly used in the US before?
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It's toxic (disrupts bone protein synthesis and triggers aplastic anemia). Also, typhoid fever was not common in the US.
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Why are Chloramphenicols starting to be used in the US now?
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Returning to it to treat drug-resistant bacteria.
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Are Macrolide antibiotics broad- or narrow-spectrum?
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Broad
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What are Macrolide antibiotics derived from?
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Strep. erythreus -> ?
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Name 3 examples of Macrolide antibiotics.
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Erythromycin, Azithromycin, Clarithromycin
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Is Erythromycin bactericidal or bacteriostatic?
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Bacteriostatic
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Describe the structure of Erythromycin.
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Macrocyclic lactone ring bound to desosamine and cladinose sugars.
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Describe the structure of Azithromycin and Clarithromycin.
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Modifications to Macrolide (Macrocyclic lactone ring bound to desosamine and cladinose sugars).
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What is the specific action mechanism used by all Macrolide antibiotics against bacteria?
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Reversibly binds to 23S RNA of 50S ribo-unit. Blocks elongation.
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What is Erythromycin used against?
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Mycoplasma, legionella, chlamydia, campylobacter, gram+ (for pts. penicillin-allergic)
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What does Erythromycin encounter resistance from?
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Methylation of 23S rRNA (blocks antibiotic binding), erythromycin esterase (destroys lactone ring), bugs that pump it out
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What are Azithromycin and Clarithromycin used against?
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Mycobacterial infections (mycobacterium avium complex)
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What is 1 example of a Lincosamide antibiotic?
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Clindamycin
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What type of antibiotic is Clindamycin?
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Lincosamide
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What is the specific mechanism of action used by Clindamycin against bacteria?
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Binds to 50S ribosome and interferes w/ peptidyl transferase. Blocks incoming tRNAs and elongation.
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What is Clindamycin used against?
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Staphylococcus, Clostridium and other anaerobic gram- bacilli
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What is Clindamycin derived from?
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Strep. lincolnensis -> ?
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What is 1 example of a Streptogramin antibiotic?
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Quinupristin-dalfopristin (Synerced)
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What are the two antibiotic components of Synerced?
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Quinupristin and Dalfopristin
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Describe the structure of Synerced (Quinupristin-dalfopristin).
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Cyclic peptides administered in two synergistic groups (A and B)
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What is the specific action mechanism of Synerced (Quinupristin-dalfopristin) against bacteria?
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Dalfopristin binds 50S ribo-unit, blocks elongation and facilitates quinupristin binding. Quinupristin triggers premature peptide chain release
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What is Synerced (Quinupristin-dalfopristin) used against?
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Staphylococci, streptococci, Entero. faecium. Restricted to treating vancomycin-resistant E. faecium
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What is Synerced (Quinupristin-dalfopristin) derived from?
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Streptomyces -> ?
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What usage is Synerced (Quinupristin-dalfopristin) restricted to?
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Vancomycin-resistant Enterococci faecium
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Name 5 examples of Quinolone-type antibiotics.
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Nalidixic acid, Ciprofloxacin, Levoflaxacin, Gatofloxacin, Moxifloxacin
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Name 4 examples of Fluoroquinolone-class Quinolone antibiotics.
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Ciprofloxacin, Levoflaxacin, Gatofloxacin, Moxifloxacin
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What is the general structure of Quinolone antibiotics?
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Two-ring quinolone nucleus (modifications yield Fluoroquinolones)
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What is the specific action mechanism used by all Quinolone antibiotics against bacteria?
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Binds to DNA gyrase. Blocks DNA replication, recombination, repair.
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What kind of antibiotic is Nalidixic acid?
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Quinolone
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What was Nalidixic acid used to treat?
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UTIs from gram-
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Why is Nalidixic acid not used often anymore?
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Most bugs are resistant to it now; this resistance developed very rapidly.
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What are Quinolones derived from?
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Nothing - they are synthetic
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What are (newer) Fluoroquinolones used against?
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Gram+ and gram- (that's all he wrote). They're pretty strong against them, he said.
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What do Fluoroquinolones encounter resistance from?
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Mutation of DNA gyrase alpha subunit, porin mutation for less uptake (Pseudomonas, oxacillin-resistant Staphylococci, Enterococci)
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Is Rifampin bactericidal or bacteriostatic?
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Bactericidal (for Mycobacterium tuberculosis).
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What antibiotic class do Rifampin, Rifabutin, and Metronidazole belong to?
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Nothing! They stand alone. They are, however, DNA/RNA synthesis inhibitors.
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What is the exact action mechanism of both Rifampin and Rifabutin?
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Binds to RNA polymerase. Stops RNA synthesis initiation.
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What is Rifampin used against?
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Mycobacterium tuberculosis, aerobic gram+ cocci (Staph, strep)
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What is Rifabutin used against?
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M. avium in addition to bugs Rifampin is used against [Mycobacterium tuberculosis, aerobic gram+ cocci (Staph, strep)]
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What do Rifampin and Rifabutin encounter resistance from?
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Mutation of RNA polymerase beta subunit (gram+). Gram- (intrinsic decreased uptake).
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Why do you want to use Rifampin only in effective antibiotic cocktails?
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Resistance develops rapidly when used by itself
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How do you counter bacterial resistance to Rifampin?
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Use it in effective antibiotic cocktails
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What is Rifampin derived from?
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Strep. mediterranei -> rifamycin B -> semisynthetic derivative
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What is Rifabutin derived from?
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Rifamycin -> ?
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What is the specific action mechanism used by Metronidazole against bacteria?
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DNA strand breaks induced by cytotoxic compounds from nitroreductase
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What is Metronidazole used against?
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Originally Trichomomas vaginitis; now amebiasis, giardiasis, "serious anaerobic infections" (Bacteriodies fragilis)
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What does Metronidazole encounter resistance from?
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Bugs that decrease uptake of antibiotic or eliminate cytotoxic compounds before they hit DNA
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Are Sulfonamides broad- or narrow-spectrum?
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Broad
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What is the specific action mechanism of Sulfonamides in general?
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Compete w/ PABA (para-aminobenzoic acid), prevents folic acid synthesis (necessary for some bacteria).
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What are general Sulfonamides used against?
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Gram+ and Gram- (nocardia, chlamydia)
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What do general Sulfonamides encounter resistance from?
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Bugs that have permeability barriers (Pseudomonas) or use of exogenous thymidine (Enterococci)
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What type of antibiotic is Sulfisoxazole?
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Sulfonamide
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What is Sulfisoxazole used against?
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acute UTIs (E. coli), normal sulfonamide range [Gram+ and Gram- (nocardia, chlamydia)]
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Name 3 examples of Sulfonamide antibiotics.
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Sulfisoxazole, Trimethoprim, Sulfamethoxazole
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What is the specific action mechanism of Trimethoprim?
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Inhibits dihydrofolate reducatase conversion of dihydrofolate to tetrahydrofolate. Blocks formation of thymidine, methionine, glycine, and some purines.
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What does Trimethoprim encounter resistance from?
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Bugs with decreased affinity of DHFR for trimethoprim
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What is the advantage in pairing Trimethoprim with Sulfamethoxazole? Together, what are they used against?
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Synergistic effects when together. Activity against "large variety" of Gram+ and Gram-; "drug of choice" for acute/chronic UTIs, otitis media, and lower respiratory tract infections (Pneumoncystis carinii, gonorrhea)
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What are Dapsone and p-aminosalicylic acid (PAS) used against?
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Mycobacterial infections
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