1-Principles of Antimicrobial Therapy Flashcards
4 methods of antimicrobial agent action
- Inhibit cell wall synthesis
- Inhibit cell membrane function
- Inhibit protein synthesis
- Inhibit nucleic acid synthesis
Define a bacteriostatic agent
Inhibits growth of microbe (stasis)
does NOT reduce number of microbes
Define a bactericidal agent
Kills susceptible microbes and reduces number of viable microbes
Define a time-dependent killing rate
Ability to kill microbes depends on length of time concentration of antibiotic is above minimal bactericidal concentration (MBC)
Ability to inhibit further growth depends on time above minimum inhibitory concentration (MIC)
Define concentration-dependent killing rate
Ability to kill microbes increases as concentration of antimicrobial increases
Name 3 classes of antimicrobials that work in a concentration-dependent manner
Aminoglycosides, fluoroquinolones, and daptomycin
Define post-antibiotic effect
Microbial death/ inhibition continues for a period of time after concentration of drug drops below MBC/MIC
Is susceptibility based on MIC or MBC?
MIC (minimal inhibitory concentration)
Test via disk diffusion, broth dilution, Etest
Name 7 ways bacteria can acquire resistance to antibiotics
- enzyme inactivation of antibiotics
- Alteration of cell wall target proteins (PBPs)
- Increase in cell wall thickness
- Decrease in cell membrane permeability (porin channels)
- Alteration of ribosomal targets
- Alteration of enzyme target (DNA gyrase)
- Alteration of efflux pumps
Name organs that commonly have low antimicrobial concentrations
Bone, brain, prostate gland, abscesses, infected heart valves
What is a superinfection and what organisms are common?
Secondary infections due to use of broad spectrum agents and the killing of normal flora
C. diff & yeast infections are common superinfections
What are the common side effects to antibiotic use?
hypersensitivity reactions (most common)
phlebitis (parenteral), photosensitivity, GI intolerance, superinfection, renal failure
