anti-microbials Flashcards
antibiotic resistance: recall the mechanisms commonly used by bacteria to become resistant to drugs
4 causes of antibiotic resistance
unnecessary prescription, livestock farming, lack of regulation, lack of development
5 types of antibiotic resistance
destruction enzymes, additional target, alteration of target, alteration in drug permeation, hyperproduction
how do destruction enzymes (B-lactamases) destroy B-lactam antibiotics
B-lactamase hyrolyses C-N bond of B-lactam ring
how do penicillins differ when targeting antibiotics with destruction enzymes
some are only effective against gram +ve or gram -ve (can’t enter), and some (e.g. amoxicillin) must be co-administered with something else (clavulanic acid) to be B-lactamase resistant; flucloxacillin and temocillin are B-lactamase resistant
decribe additional target antibiotic resistance
bacteria produce another target that is unaffected by drug
E. coli as example of bacteria that shows additional target antibiotic resistance
produce different DHF reductase enzyme, so resistant to trimethoprim
decribe alterations in target enzymes antibiotic resistance
alteration of enzyme targeted by drug, so enzyme still effective but drug now ineffective
S. aureus as example of bacteria that shows alterations in target enzymes antibiotic resistance
mutations in ParC region of topoisomerase (DNA gyrase) allows resistance to quinolones
describe alterations in drug permeation antibiotic resistance
reductions in aquaporins (decrease drug influx) and increased efflux systems
what type of bacteria use alterations in permeation antibiotic resistance
gram -ve
describe hyperproduction antibiotic resistance
bacteria significantly increase levels of DHF reductase, so still destroys enzyme but is less effective as much more enzyme (must produce more protein)
E. coli as example of bcteria that show hyperproduction antibiotic resistance
produce additional DHF reductase enzymes, making trimethoprim less effective
