Lecture 8-Antimicrobials Flashcards
The lowest concentration of antibiotic required to prevent growth is the ___
minimum inhibitory concentration (MIC)
The lowest concentration of antibiotic required to kill bacteria is the ___
minimum bactericidal concentration (MBC)
You can compare MICs of different antibiotics to each other–T/F?
False–cannot compare MICs of different antibiotics to each other
You can, however, compare MIC of one single antibiotic to different organisms (i.e.: MIC of cipro for klebsiella vs. pseudomonas)
Bacterial sensitivity–disc diffusion technique–multiple discs of antibiotic are placed on an inoculated growth medium; antibiotic diffuses outward from the discs; antibiotic susceptibility is determined by the ___ around each disc
antibiotic susceptibility is determined by the radius around each disc
What is the difference between bactericidal and bacteriostatic?
Bactericidal = kills the bacteria
Bacteriostatic = stops the bacteria from replicating (but does not kill the existing bacteria)
Penicillins, cephalosporins, aminoglycosides, vancomycin, quinolone, aztreonam, imipenem, bacitracin, and polymyxins are all bacteri___
bactericidal
Tetracyclines, chloramphenicol, eryrthromycin, clindamycin, sulfonamides, and trimethoprim are all bacteri___
bacteriostatic
Narrow-spectrum antibiotics kill ___ (many/few) bacteria
few bacteria
examples = penicillin G, erythromycin, clindamycin
Broad-spectrum antimicrobials kill ___ (many/few) bacteria
many bacteria
examples = ampicillin, cephalosporins, ahminoglycosides, tetracyclines, chloramphenicol, quinolones
Time-dependent killing = antibiotics that increase their rate of microbial killing with concentrations up to ___x MIC
4x MIC
Time-dependent killing–greater concentrations ___ (do/do not) kill bacteria faster or in greater numbers
greater concentrations do NOT kill bacteria faster or in greater numbers
Time-dependent killing–clinical efficacy is related to the duration for which these levels are maintained–T/F?
True
What (3) antibiotic classes demonstrate time-dependent killing?
- Beta-lactams
- Monobactams (aztreonam)
- Macrolides (erythromycin, clindamycin)
Continuous infusion of time-dependent killing antibiotics ___ (has/has not) shown to be more effective than intermittent boluses
continuous infusion of time-dependent killing antibiotics has NOT shown to be more effective than intermittent boluses
What term describes the following?–some antibiotics continue to suppress the growth of bacteria even after the antibiotic is no longer detectable
Post Antibiotic Effect (PAE)
PAE is demonstrated virtually for all antimicrobials–T/F?
True
PAE can be ___ (increased/decreased) in acidic, infected media
decreased
During the PAE phase, bacteria are ___ (more/less) susceptible to killing by leukocytes–this is known as what?
During the PAE phase, bacteria are MORE susceptible to killing by leukocytes–this is known post antibiotic leukocyte effect
What is the judicious use of antibiotics to reduce resistance development?
Antimicrobial stewardship
(2) types of antibiotic resistance–___ and ___
intrinsic and acquired
___ (intrinsic/acquired) resistance is natural resistance to the antimicrobial
Intrinsic resistance is natural resistance to the antimicrobial
___ (intrinsic/acquired) resistance reflects a genetic alteration in the bacteria that renders a once effective antimicrobial ineffective
Acquired resistance reflects a genetic alteration in the bacteria that renders a once effective antimicrobial ineffective
What are some ways that acquired antibiotic resistance can occur?–___ (increased/decreased) permeability; ___ (increased/decreased) efflux pumps; ___activation; ___ of the antimicrobial target
decreased permeability; increased efflux pumps; inactivation; modification of the antimicrobial target
The majority of nosocomial (hospital-acquired) infections are ___, ___, and ___ infections
urinary, respiratory, and blood infections