Lecture 10: Antibiotics and resistance Flashcards
what is the major way in measuring antibacterial activity?
zone of inhibition
what are aminoglycosides?
antibiotics that contain sugars bonded by a glycoside linkage BUT are neuro/nephrotoxic so are reserves for if all else fail
what are some examples of aminoglycosides?
streptomycin and kanamycin
what are macrolides?
antibiotics that contain lactone rings bonded to sugars and target the 50s subunit of ribosomes
what are tetracyclines?
antibiotics that contain 4 rings and target the 30s unit of ribosomes
what is the name of natural penicillin?
benzylpenicillin (penicillin G)
what are the 3 artificial penicillins?
methicillin, oxacillin, and ampicillin
what are B-lactam antibiotics?
include penicillins, cephalosporins and cephamycins
which type of bacteria are pencillins mostly effective toward?
gram positive
where do penicillins target?
cell wall synthesis by binding to the Penicillin Binding Proteins (PBPs) weakening the peptidoglucan layer
what do quinolones do?
inhibit DNA gyrase by binding to the subunit A and acting as an non-competitive inhibitor
what is vancomycin?
antibiotic that inhibits cell wall biosynthesis and used for the treatment of C.difficile
what is methicillin?
an antibiotic that inhibits cell wall biosynthesis
why are some antibiotics inaffective against gram negative bacteria?
cannot diffuse across the outer membrane so cant access the peptidoglucan
what are the 2 pathogens resistant to all known antimicrobials?
MRSA and carbapenem resistant K.pneumoniae
what are the 5 mechanisms that are possible reasons for antibiotic resistance?
organism:
- lacks the antibiotic target structure
- impermeable to antibiotic
- inactivate antibiotic
- modify antibiotic target
- pump out antibiotic (efflux)
where are drug resistance genes located?
R plasmids
