Resistance to antimicrobial agents Flashcards
(24 cards)
Reasons for antibiotic development dwindling…
- Economic barriers
- Low return on investments
Antibiotic resistance is associated with…
- Increased risk of hospitalisation
- Increased length of stay
- Increased hospital costs
- Increased risk of transfer to ICU
- Increased risk of death
What kind of drugs act on cell wall synthesis
- Cycloserine
- Vancomycin
- Bacitracin
- Penicillins
- Cephalosporins
- Monobactams
- Carbapenems
Act on protein synthesis (50S inhibitors)
- Erythromycin
- Chloramephenicol
- Clindamycin
- Lincomycin
Act on protein synthesis (30S inhibitors)
- Tetracyclines
- Spectinomycin
- Streptomycin
- Gentamycin
- Kanamycin
- Amikacin
- Nitrofurans
Act on protein synthesis (tRNA)
Mupirocin
Puromycin
Main mechanisms of antibiotic resistance…
1- Altered receptor sites
2- Decreased permeability of plasma membrane
3- Antibiotics removed from cell by pumps
4- Antibiotics broken down by enxymes
β-lactam group of antibiotics…
- Penicillins
- Cephalosporins
- Monobactams
- Carbapenems
β-lactams work by…
inhibiting bacterial cell wall synthesis when they bind to penicillin binding proteins.
S. aureus problems
Boils, wound infection, necrotising fasciitis, pneumonia, bone infections, endocarditis, meningitis, pacemaker related infections, toxic shock syndrome.
How many strains of S. aureus are now resistant to penicillin?
80-90%
Why is S. aureus resistant to β-lactam antibiotics?
Production of penicillinase, a β-lactamase enzyme that destroys certain β-lactam antibiotics by hydrolysing the β-lactam ring.
How did MRSA become β-lactam resistant?
Acquired a new penicillin binding protein (PBP2A) encoded by gene mecA.
Penicillin binding protein 2A has a ______ affinity for β-lactam antibiotics so it can carry on its job.
Low
Treatments for MRSA
Glycopeptides
Vancomycin
Teicoplanin
Next problem after MRSA?
GRSA (glycopeptide resistant s aureus)
Enterobacteriaceae carry classical β-lactamases that…
break down penicillin, amoxicillin and piperacillin
Treatment for enterobacteriaceae
2nd & 3rd gen cephalosporins
Example of enterobacteriaceae
E. coli
Cephalosporin-resistant E. coli and K. pneumoniae treatment
IV carbapenems
Symptoms of C. diff pseudomembranous colitis (PMC)
Abdo pain, malaise, inflamed mucosa/plaques (large intestine). Mortality of 25%
C. diff toxic mega colon
Toxic dilation of colon, gut perforation, 1-3% fulminant colitis
R plasmids carry resistance genes like…
β-lactamases, PBPs, antibiotic-modifying enzymes, efflux pumps
Resistance passed by plasmids by
conjugation
