Lecture 4 Flashcards
selective toxicity
kill or inhibit the growth of a microorgansim without harming host cells
antibiotic
natural antibiotic
antimicrobial
man-made antibiotic
bacteriostatic
inhibit growth
bacteriocidial
killing
which type of antibiotic is used when host defenses can be counted on?
bacteriostatic
which type of antibiotic is used druing invasive infection: bacteremia, meningitis, endocarditis
bactericidal
which type of antibiotic would you use with an immunocompromised patient?
bactericidal because you can’t count on the immune system to help
antibiotic synergism
combination of two antibiotics with enhanced bactericidal activity when used together
antibiotic antagonism
combination of antibiotics in which one interferes with the activity of the other
broad spectrum
effective against a large variety of bacteria
narrow spectrum
effective against only a small subset of bacteria
advantage + disadvantage of broad spectrum
A: increased likelihood of effectiveness against a bacterial infection of unknown etiology
D: increased likelihood of disrupting the patients normal microbiota
advantage + disadvantage of narrow spectrum
A: avoids disruption of the normal microbiota
D: must have the specific disease causing bacteria identified in order to choose the correct antibiotic
order: narrow broad extended expanded
increasing specificity:
narrow expanded broad extended
True or False: antibiotics do not cause resistance
TRUE
sensitive (S)
infection may be treated with dosage regimen of an antimicrobial agent recommended
intermediate (I)
Infection may be treated in body sites where the drug are physiologically concentrated or when a high dosage of drug can be used
resistant (R)
resistant isolated are not inhibited by the usually achieved concentrations of the antimicrobial
True or false: antibiotics are only useful for treating bacterial infections.
TRUE
empiric theory
treatment while waiting for lab results (broad spectrum)
targeted theory
refined treatment (narrow spectrum)
antibiotic prophylaxis
prevent rather than treat the disease (pre-surgery, immunocompromised, exposure)
5 mechanisms of antibiotic resistance
- breakdown of antibiotic
- chemical modification of antibiotic
- alteration of traget
- altered permeability, decreased influx or increased efflux
- lack of target
minimum inhibitory concentration MIC
lowest concentration of antibiotic that inhibits growth
minimum bactericidal concentration MBC
lowest concentration of antibiotic that kills 99.9%
3 tests for antibiotic susceptibility
- Disk diffusion/ Kirby-Bauer test
- circle of inhibition - E-test
- strip of inhibition - Broth culture
- dilutions