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54 Cards in this Set

  • Front
  • Back
bacteriostatic
able to reversibly inhibit essential metabolic processes,

but not kill, susceptible bacteria
MIC =
minimum inhibitory concentration
minimum inhibitory concentration
lowest concentration of a given ABS that prevents growth under standardized conditions
MBC
minimum bacterial concentration
minimum bacterial concentration
lowest concentration of a given ABS required to kill 99.9% of the bacteria in a suspension in a given time
breakpoint
concentration of an ABS that can be achieved in the bloodstream with optimal therapy
spectrum
range of genera and species against which an ABS is effective
TI
therapeutic index
therapeutic index
ratio of TOXIC DOSE

to THERAPEUTIC DOSE

(should be greater than 1!)
5 desirable properties in an antimicrobial
selective toxicity

bactericidal vs. bacteriostatic

no development of resistance

not allergenic

soluble, stable and active in body fluids
5 bacterial processes inhibited by ABS
cell wall synthesis

protein synthesis

nucleic acid metabolism

membrane function

key enzymatic reactions
5 mechanisms of resistance
access

target site modification

bypass

binding

inactivation
innate/intrinsic resistance
all members of a species are resistant due to some specific quality
acquired resistance
an individual strain develops resistance due to mutation or acquisition of resistance genes
5 organisms of concern wrt ABS resistance
S. aureus
E. faecalis
Strept. pneumoniae
N. gonorrhoeae
S. enterica
3 methods of antimicrobial susceptibility testing
broth dilution method

agar dilution method

disk diffusion method (Kirby-Bauer)
3 cell wall synthesis inhibitors
beta-lactams

vancomycin

bacitracin
4 types of beta-lactams
penicillins

monobatams
carbapenems
cephalosporins
mechanism of action for beta-lactam ABS
blocks transpeptidation reaction necessary for the formation of peptidoglycan crosslinks
molecular targets of beta-lactam ABS
penicillin binding proteins
what type of ABS requires actively growing cells to be effective?
beta-lactams (penicillins)
Provided organism is susceptible, what class of ABS is the drug of choice?
beta-lactams

high TI & bactericidal
beta-lactamase inhibitors
clavulanic acid
clavulanic acid
beta-lactam that acts as a suicide inhibitor of beta-lactamase
what ABS is effective only against gram-positive organisms?
VANCOMYCIN

BACITRACIN

effective only against gram-positive organisms
mechanism of action for vancomycin
blocks cell wall synthesis

blocks release of peptidoglycan precursor
Vancomycin resistance is due to___
target site modification
what type of molecule is vancomycin
glycopeptide
Bacitracin is a ...
cyclic polypeptide (mixture) ABS
mechanism of action of bacitracin
blocks cell wall synthesis by blocking cycling of bactroprenol carrier
What ABS are effective only against gram negative bacteria?
polymixin

colistin
mechanism of action of polymixin and colistin
alters permeability of cell membranes by binding to LPS and phospholipids
ABS that are very toxic nephrotoxins
polymixin

colistin
mycobacterial cell wall inhibitors
INH, ethionamid

ethambutol

cycloserine
class of ABS that cause irreversible inhibition of protein synthesis
aminoglycosides
route of delivery for aminoclycosides
poorly absorbed orally

usually given IV
examples of aminoglycosides
stremptomycin
gentamycin
neomycin
what class of ABS requires ox-phos to be actively transported into target cells?
aminoglycosides
mode of action for tetracyclines
reversible inhibition of protein synthesis
are tetracyclines bactericidal or bacteriostatic
bacteriostatic
common broad-spectrum bacteriostatic
tetracycline
mode of action for chloramphenicol
blocks protein synthesis by inhibiting peptidyl transferase
chloramphenicol is bactericidal or bacteriostatic?
bacteriostatic
chloramphenicol toxicity can can cause...
aplastic anemia
mode of action for macrolides and lincosamides
reversible inhibition of protein synthesis
examples of mocrolides/lincosamides
erythromycin
axithromycin
clindamycin
lincomycin
T/F: macrolides are bacteriostatic and broad spectrum?
TRUE
class of ABS developed specifically for use against vancomycin resistant, gram-positive organisms and multi-drug resistant staph
oxazolidinones
Linezolid
first oxazolidinone approved by FDA
cirpofloxacin - what class ABS?
quinolones

broad spectrum fluorquinolone
mode of action for rifampicin
blocks DNA-dependent RNA polymerase
what ABS class is active only against anaerobic bacteria?
metronidazole
2 metabolic inhibitors
trimethoprim

sulfanoamides
mode of action for sulfanamides
reversibly block steps in folic acid synthesis