Antibiotics Flashcards
Define post-antibiotic effect (PAE)?
Continued suppression of bacterial growth after a short exposure to antimicrobial agents
Define synergism
Together ABX have enhanced inhibition of organisms than either agent alone (may see decrease MIC)
Define antagonism
Together ABX have decreased inhibition or killing than when either agent is used alone
Define time-dependent
The amount of bacterial killing depends on time the drug stays above MIC
What are the PK/PD parameters for time-dependent?
T (time) > MIC (minimum inhibition concentration)
Name 5 examples for time-dependent antimicrobial killing?
Beta-lactams Macrolides Clindamycin Linezolid Vancomycin
Define concentration-dependent
The amount of bacterial killings depends on Cmax above the MIC
What are the PK/PD parameters for concentration-dependent?
Peak/MIC
Name 4 examples for concentration-dependent antimicrobial killing?
Aminoglycosides
Fluoroquinolones
Daptomycin
Metronidazole
Name the antibiotic(s) of this classification
- Pattern of activity = time-dependent and minimal PAE
- Goal of therapy = Maximize duration of exposure
- PK/PD = T > MIC
Beta-lactams
Linezolid
Name the antibiotic(s) of this classification
- Pattern of activity = time-dependent and minimal PAE
- Goal of therapy = Maximize amount of drug
- PK/PD = 24h-AUC/MIC
Vancomycin
Name the antibiotic(s) of this classification
- Pattern of activity = time-dependent and moderate to prolonged PAE
- Goal of therapy = Maximize amount of drug
- PK/PD = 24h-AUC/MIC
Azithromycin
Clindamycin
Name the antibiotic(s) of this classification
- Pattern of activity = concentration-dependent and prolonged PAE
- Goal of therapy = Maximize concentration
- PK/PD = Peak/MIC
Aminoglycosides
Fluoroquinolones
Daptomycin
Metronidazole
What are 3 advantages for using extended infusions?
- Superior PD profile (more f T > MIC)
- Allows time between doses for administration of drugs through the same IV line
- Cost
What are 5 reasons for using antibiotic combinations?
- Broad spectrum empiric therapy
- Polymicrobial infections
- Decrease resistance
- Decrease dose-related toxicity
- Increase inhibition or killing
Name 3 types of antibiotic combinations that have a synergistic mechanism?
TMP/SMX
Beta-lactams/Beta-lactamase inhibitors
PCN and gentamycin
Name 3 types of antibiotic combinations that an antagonistic mechanism?
Vancomycin and linezolid
PCN and TCNs
2 beta-lactams
What is the synergistic mechanism of TMP/SMX?
Blockade of sequential steps in a metabolic sequence
What is the synergistic mechanism of beta-lactams/beta-lactamase inhibitors?
Inhibition of enzymatic inactivation
What is the synergistic mechanism of PCN and gentamycin?
Enhancement of antibiotic uptake
What is the antagonistic mechanism of vancomycin and linezolid?
Inhibition of cidal activity by static agents
What is the antagonistic mechanism of PCN and TCNs?
Inhibition of cidal activity by static agents
What is the antagonistic mechanism of 2 beta-lactams?
Induction of enzymatic inactivation
Explain the rationale of extended infusions
The amount of time the free or non-protein drug concentration exceeds the MIC (f T > MIC)
