Antimicrobial Therapy Flashcards
What are the four sterile sites in the body?
Blood: Staph and Strep
CSF: Staph and Strep
Urine: Gram- enterics, Staph and strep
Lungs: S. pneumoniae
What are the 3 approaches to antibiotic therapy?
- Prophylaxis: Used to prevent infection
- Empiric: Used to treat suspected pathogen as you wait for culture results.
- Specific: Used to treat known pathogens.
What is the MIC?
MIC: Lowest concentration of drug that inhibits visible growth under standard conditions.
What is the MBC?
The lowest concentration of the antibiotic that kills 99.9% of the original inoculum
What is the Breakpoint MIC?
The concentration of antibiotic that can be achieved in the bloodstream with optimal therapy.
How do you interpret pathogen susceptibility to a drug?
Sensitive: MIC Breakpoint
Discuss Concentration-dependent killing
Peak levels determine the adequacy of treatment. The greater the AUC:MIC ratio, the greater the antibiotic effect.
Discuss Time-dependent killing
Drug level must achieve MIC at site of infection and be maintained to be effective; The longer the antibiotic concentration is greater than the MIC, the greater the effect.
Discuss the Post-antibiotic effect
Suppression of microbial growth after antibiotic concentration falls below MIC
What are the difficult sites to reach with antibiotics?
CSF, lungs, bone, heart and abscesses
What are the 3 characteristics of antibiotics that allows dosing to be the same?
- Good oral bioavailability
- Broad therapeutic window
- No adverse effects associated with peaks and troughs.
Which drugs inhibit Cell wall synthesis?
Beta-lactams;
Penicillins, Cephalosporins, Carbapenems, Monobactam, Vancomycin, Dalba/Tela/Oritavancin
Which drugs inhibit the plasma membrane?
Daptomycin
Which drugs inhibit 30S ribosome protein synthesis?
Aminoglycosides, Tetracyclines, Tigecycline
Which drugs inhibit 50S Ribosome protein synthesis?
Macrolides, Clindamycin, Line/Tedizolid, Quinopristin-dalfospristin.
Which drugs inhibit DNA replication?
Quinolones and Metronidazole
What drug inhibits RNA synthesis?
Rifampin
Which drugs inhibit enzyme activity?
Sulfonamides, Trimethoprim
Describe Synergism
2 or more agents working together to allow dosage reduction and/or faster/enhanced drug effect; Different MOAs and can penetrate site of infection
Describe Antagonism
When an agent interferes with the effects of another agent.
Differentiate allergies from sensitivities
Allergies require immune responses that damage normal tissue. Sensitivities are NOT immune-mediated.
