Antibiotic Resistance Flashcards
Define antibiotic era
ter used to describe the time since the widespread availability of antibiotics to treat infection
Define post-antibiotic era
term used to describe the time after widespread antibiotic resistance has reduced the availability of antibiotics to treat infection
What are the risks of empiric therapy?
risk of undertreatment, risk of excessively broad-spectrum treatment
What does sensitivity testing determine?
whether MIC is above a predetermined ‘breakpoint’ level
What testing can enable the transition from empiric to targeted antibiotic therapy?
sensitivity testing
How do you carry out a sensitivity test?
culture of micro-organism in the presence of antimicrobial agent
What are the 6 resistance mechanisms?
no target reduced permeability altered target over-expression of target enzymatic degradation efflux pump
Why are gram-negative bacilli resistant to vancomycin?
Gram-negatives have an outer membrane that is impermeable to vancomycin
Why are anaerobic organisms resistant to gentamicin?
uptake of aminoglycosides requires an O2 dependant active transport mechanism
Name 3 antibiotics (and their bacteria) effected by target alteration?
flucloxacillin: MRSA
vancomycin: VRE
trimethoprim: gram-negative bacilli
enzymatic degradation causes gentamicin resistance in what?
aminoglycoside modifying enzymes
enzymatic degradation causes chloramphenicol resistance in what?
chloramphenicol acetyltransferase (CAT)
enzymatic degradation causes penicillins and cephalosporins resistance in what?
beta-lactamases
By what method are circular DNA sequences transmitted within and between species (normally)?
conjugation - when resistance genes are encoded in plasmids
What enables horizontal transfer of resistance?
transposons and intergrons
