Clinical Use of Abx Flashcards
Describe why endocarditis is considered to be in a protected local environment. Tx?
fibrin/platelet mixture protects from host defense mechs; bactericidal therapy
Describe why intracellular infections are considered to be in a protected local environment. Tx?
some bugs thrive intracellularly; need to penetrate these cells eg rifampin, tetracycline, erythromycin
What is a consideration for drugs and the bladder? What drugs should be used?
- some drugs concentrate there, changing susceptibility - quinolones as a group are good EXCEPT moxifloxacin
What does susceptible (S) mean?
bacteria will probably respond to the Abx
Describe why abscesses are considered to be in a protected local environment. Tx?
drugs can’t penetrate; need surgical drainage
Name 3 susceptibility tests.
- broth dilution 2. disk diffusion (Kirby-Bauer) 3. E test
What is the MBC?
the lowest conc of the Abx that kills 99.9% of the initial inoculum
_____ Abx have MBC concentrations many fold higher than the MIC concentration.
Bacteriostatic
What is the MIC?
the lowest concentration of Abx that prevents visible bacterial growth
Bacteriostatic Abx have MBC concentrations ____ than the MIC concentration.
many fold higher
Describe why meningitis is in a protected local environment. Tx?
within the BBB and protected from host defense mechs; bactericidal therapy
What does resistance (R) mean?
infection will probably not respond to the Abx
What is the E test?
strip containing a gradient of Abx is plated with a bug- clearing makes ellipse shape- where ellipse point meets the strip is the MIC
At ____, the Abx should have a maximal serum conc that exceeds the MIC of the bacteria (Cp>MIC).
normal doses
What is the MBC used to determine?
bactericidal vs bacteriostatic