Lecture 4 (20) Antibiotics Flashcards
selective toxicity
kill or inhibit growth of microorganism without harming host cells
what’s another name for antimicrobial
antibiotic
bacteriostatic
inhibits the GROWTH of bacteria but doesn’t KILL it
relies on immnocompetent pt to kill it off itself
bacteriocidal
kills of bacteria itself; for pt that lack immune system to fight off infection
antibiotic synergism and antagonism
synergism- two antibiotics enhance eachother’s effects
antagonism-antibiotics that interfere with one another
broad vs. narrow spectrum-advantages/disadvantages
broad- effective against large number of bacteria so good for infection of unknown etiology but bad because may disrupt normal biota
narrow- effective against a small number of bacteria; good to not disrupt normal biota/ bad because need to know what infection is first
what causes antibiotic resistance?
it is NOT antibiotics, if mutations in bacteria that make it antibiotic resistant are developed, they can pass that mutation horizontally spreading that resistance
what are the categories of antibiotic resistance and what do they mean?
SIR
S-sensitive- infection may be treate with the dosage regimen of an antimicrobial agent recommended
I-intermediate- infection may be treated in body sites where the drug are physiologically concentrated or when a high dosage of drug can be used
R-resistant- resistant isolates are not inhibited by the usually achieved concentrations of the antimicrobial
why shouldn’t I prescribe antibiotics willy nilly
because giving antibiotics will help to select for antibiotic resistant bacteria and kill good ones off and cause an increase in resistance in the pop
empiric therapy
-treatment while waiting for lab results that usually includes broad spectrum antibiotics
targeted therapy
- refined treatment
- usually narrow spectrum
what are 5 ways that a bacteria can develop antibody resistance
1) Breakdown of an antibiotic via hydrolysis
2) Chemical modification of an antibiotic to render it inactive
3) Alter target via mutation or gene acquisition
4) Altered permeability, decreased influx or increased efflux
5) lack of target
minimum inhibitory concentration (MIC)/minimumbacteriocidal (MBC) concentration
lowest amount of antibiotic that inhibits growth/ lowerest amount of antibiotic that kills 99.9% of bacteria
Kirby baur test
-measures bacterial resistance to antibiotics by dropping antibiotic capsules into plate of bacteria
if clear ring appears, bacteria is killed by antibiotic, if not, it is resistant
E test
put bacteria on a plate with strips of different antibiotic bacteria around
you can look at each strip and see where there is clearing
outside circle is hi conc of antibiotic, inside is low
