Principles of Antimicrobial Therapy Flashcards
How does sulfonamide work?
competitive inhibitor of dihydropteroate synthetase. PABA analog. bacteria cannot make folic acid. Bacteriostatic.
How does trimethoprim work?
inhibits dihydrofolate reductase. bacteria cannot make nucleic acids. Bactericidal.
What happens when trimethoprim and sulfonamide as used together?
call bactrin and is a bactericidal effect.
What do penicillins and cephalosporins do?
block the later steps in cell wall synthesis. Blocks transpeptidase rxn. Cells must be dividing for this to work.
What do PBPs do?
penicillin binding proteins cross-link peptidoglycan in the cell wall
What is the result of the reaction between penicillin and tetracycline?
Tetracycline is bacteriostatic and penicillin is bactericidal. When used in combo, tetracycline stops the bacteria from growing, but penicillin needs bacteria to be growing to be efficient (disrupts cell wall synthesis) so it is an ineffective combo in treating meningitis.
What is a good combination when treating TB?
isoniazid and rifampin
What is a good combo for mixed infections and prophylaxis? (endocarditis?)
penicillin and aminoglycosides. Penicillin inhibits cell wall synthesis and then any remaining bacteria are destroyed by aminoglycosides which can now enter the cells (are very polar). They prevent formation of initiation complex during translation (binds 30S)
What is a good combo for pneumocystis jiroveci pneumonia?
trimethropim and sulfamethoxazole
Are aminoglycosides cidal or static?
bactericidal
Which antibiotics cause liver damage?
tetracyclines and isoniazid
What antibiotic inhibits P450 enzymes?
chloramphenicol
What antibiotics cause nephrotoxicity?
sulfonamides, aminoglycosides, and expired tetracyclines
What antibiotics cause neurotoxicity?
Large doses of penicillin G, aminoglycosides, and tetracyclines (in infants)
What antibiotics cause blood and bone marrow toxicity?
Chloramphenicol, sulfonamides, nitrofurantoin (in patients deficient in glucose-6-phosphate dehydrogenase)
