Introduction to Antibiotics Flashcards
What antibiotic agents inhibit cell wall synthesis?
- ß-lactams
- Vancomycin
- Daptomycin
- Bacitracin
What antibiotic agents act directly on the cell membrane of the microorganism (affect permeability → leads to leakage of intracellular compounds)?
Detergents (polymyxin)
What antibiotic agents interfere with protein synthesis via interaction with bacterial ribosomes?
- Chloaporphenicol
- Tetracyclines
- Macrolides
- Clindamycin
- Streptogramins
- Ketolides
What antibiotic agents interfere with protein synthesis via blocking initiation?
Oxazolidinones (linezolid)
What antibiotic agents interfere with protein synthesis via inhibition of tRNA synthesis?
Mupirocin
What antibiotic agents interfere with protein synthesis via multiple mechanisms leading to disruption of RNA processing?
Aminoglycosides
What antibiotic agents inhibit DNA processing via inhibition of DNA topoisomerases?
Quinolones
What antibiotic agents inhibit DNA processing via inhibition of DNA-dependent RNA polymerase? (distinguish between direct and indirect)
-
Directly
- Rifapin
-
Indirectly
- Nitrofurantoin
What antibiotic agents block bacterial folic acid pathway?
ANTIMETABOLITES
- Trimethoprim
- Sulfonamide
What two (2) therapies are antibiotics used?
- Empirical therapy (broad spectrum)
- Definitive therapy (choosing most selectively active for the organism with least potential for toxicity)
What should be considered when selecting an antimicrobial agent?
- Decide if an antibiotic is truly necessary
- Evaluate before administration of an antibiotic (diagnosis may be masked without appropriate culture)
What is a Host Factor?
Low immune response that may result from a therapeutic failure despite appropriate and effective therapy
How can you distinguish between different host defenses? (Think: types of immunity)
-
Humoral immunity
- Inadequacy in immunoglobulins
-
Cellular immunity
- Inadequacy in phagocytic cells
What are other components (not including host defenses) that should be considered as host factors?
- Age (i.e. renal/hepatic metabolism can affect elderly and infants)
- Genetic factors (i.e. patients with G6PD may experience acute hemolysis with certain drugs)
- Pregnancy
- Drug Allergy
- Neuropathy (i.e. seizures, myasthenia gravis)
What pharmacokinetic factors should be considered when selecting antibiotic agents?
- Infection of the CSF (drug must cross BBB)
- Penetration of drug to local area (many antibiotics are highly protein bound)
- Knowledge of kidney and liver status
How can you differentiate between Bactericidal and Bacteriostatic antibiotics?
-
Bactericidal
- Directly kills bacteria
- Inhibits cell wall synthesis
- Disrupts cell membrane
- Aminoglycosides
- Inhibits DNA gyrase
-
Bacteriostatic
- Arrest growth/replication of bacteria →immune system eliminates the pathogen
- Inhibits protein synthesis (Non-aminoglycoside)
- Antifolate drugs
NOTE: Antibiotics do not fall neatly into these categories
What is defining of resistance (microorganism to antimicrobial agents)? How does it occur?
Concentration of drug required to inhibit/kill microorganism greater than concentration that can be safely achieved
- Drug fails to reach target (DEC intracellular concentration)
- Drug is inactivated
- Target is altered (change in binding site)
- Adaptations bypass need for binding site
(More detail in slide)
What is innate resistance?
Long-standing characteristic of a particular species of bacteria
What is acquired resistance?
- Mutations (random events of change) that confer selective advantage to the bacterium
- Transfer of plasmids (transduction, transformation, conjugation)
What is Transduction?
Intervention of a bacteriophage (virus that infects bacteria may contain drug-resistant DNA that could be inserted and passed down to progeny)
What is Transformation?
Incorporates DNA from environment (i.e. virus) into bacteria
What is conjugation?
Passage of genes from cell to cell by direct contact through a bridge (occurs primarily in Gram-negative bacilli)
