Antibiotics 1

1. SULFONAMIDE

   Nota:

   • Synergy with trimethoprim leads to bacteriocidal effect
   1. Competitively inhibits dihydropteroate synthetase
   2. Pregnancy, nephrotox, hemolysis

      Nota:

      • Cross placenta
2. TRIMETHOPRIM

   Nota:

   • Synergy with sulfonamide often make bacteriocidal effect
   1. Inhibits dihydrofolate reductase
3. Bacteriostatic

1. PENICILLINS, CEPHALOSPORINS
   1. Block transpeptidase rxn

      Nota:

      • by binding penicillin binding proteins
   2. Very safe!

      Nota:

      • We don't have these proteins in our cell walls
   3. Penicillin G - neurotox

      Nota:

      • From non-specific irritation
   4. Least toxic, most allergenic
2. VANCOMYCIN, BACITRACIN
   1. Block early steps in synthesis
   2. Toxic to kidneys
3. CYCLOSERINE
   1. Blocks alanine racemase

1. POLYMYXINS
   1. Form pores
   2. Bind phosphatidyl ethanolamine-rich areas of membrane
   3. Highly toxic to kidneys

      Nota:

      • We have phosphatidyl ethanolamine in our membranes Why these are toxic
   4. CHOLISTINS

      Nota:

      • Currently being made

1. Aminoglycosides
   1. Bind to 30S
   2. Bacteriocidal
   3. STREPTOMYCIN
      1. Pregnancy

         Nota:

         • 8th cranial nerve damage Skeletal defects
   4. Nephrotox, neurotox

      Nota:

      • Neurotox in infants
2. TETRACYCLINES
   1. Blocks tRNA binding 30S
   2. Bacteriostatic
   3. Pregnancy, liver tox, neurotox

      Nota:

      • Hypoplasia of fetal teeth & bones in fetus Cataracts in fetus Neurotox in infants
3. CHLORAMPHENICOL, ERYTHROMYCIN, CLINDAMYCIN
   1. Bind 50S
   2. Inhibit chain elongation
   3. CHLOR - pregnancy, inhibits P450, toxic to marrow/hemolysis

      Nota:

      • Crosses placenta
   4. CHLOR - phenytoin, coumadin

      Nota:

      • Inhibits their breakdown

1. RIFAMPIN
   1. Inhibits DNA-dependent RNA polymerase
      1. Inhibits RNA synthesis
   2. Birth control pills

      Nota:

      • Enhances breakdown
2. Quinolones
   1. CIPROFLOXACIN
      1. Blocks DNA gyrase
3. METRONIDAZOLE
   1. Inhibits nucleic acid synthesis

1. GOOD
   1. Sulfonamide + trimethoprim
   2. Isoniazid + rifampin
      1. Treat TB
   3. Penicillin + aminoglycoside

      Nota:

      • Penicillin stops cell wall formation Allows aminoglycosides to get inside
      1. Mixed infections
      2. Prophylaxis
   4. Trimethoprim + sulfamethoxazole
      1. Treat Pneumocystis carinii pneumonia

         Nota:

         • In people with AIDS
   5. Bactericidal + bactericidal or bacteriostatic + bacteriostatic
2. BAD
   1. Bactericidal + bacteriostatic
   2. Penicillin + tetracycline

1. GI

   Nota:

   • C. diff -> fatal colitis Nausea & vomiting
2. Liver tox
   1. Isoniazid

Nota:

• Antibiotics act as haptens (give immune response when attached to large molecule)