S11: antimicrobials & anticoagulants Flashcards
Describe the three types of antibiotic resistance
Multi-drug resistant: non-susceptibility to at least one agent in three or more antimicrobial categories
Extensively-drug resistant: non-susceptibility to at least one agent in all but two or fewer antimicrobial categories
Pan-drug resistant: non-susceptibility to all agents in all antimicrobial categories
Outline antimicrobial stewardship
Appropriate use of antimicrobials
Optical clinical outcomes
Minimize toxicity and other adverse events
Reduce the costs of healthcare for infections
Limit the selection for antimicrobial resistant strains
List interventions for antimicrobial stewardship
Persuasive – education, consensus, audit
Restrictive – prior authorisation, automatic stop orders
Structural – computerised records, rapid lab tests, expert systems
Describe the mechanism of action of beta-lactam antibiotics
Interfere with the synthesis of the bacterial cell wall peptidoglycan
Generally bactericidal
1) Antibiotic binds to penicillin-binding protein on bacteria
2) Inhibits the transpeptidation enzyme (links peptidoglycan chains to form rigid cell walls)
3) Disruption of bacterial cell wall structure
List types of beta-lactam antibiotics
Penicillins
Cephalosporins
Carbapenems
Describe co-amoxiclav and the role of clavulanic acid
Clavulanic acid = beta-lactamase inhibitor
Beta-lactamase = enzyme used by certain bacteria to break down beta-lactam antibiotic molecular structure
Clavulanic acid is commonly combined with amoxicillin to overcome these issue
List indications for Penicillins
Bacterial meningitis Bone and joint infections Skin and soft tissue infections Otitis media Pneumonia UTIs STIs
List examples of cephalosporins
Cefalexin
Ceftriaxone
List indications for cephalosporins
Septicaemia Pneumonia Meningitis Biliary tract infections UTIs (especially in pregnancy or in patients unresponsive to other drugs) Sinusitis
List antibacterials affecting bacterial protein synthesis
Tetracyclines
Macrolides
Nitrofurans
Describe tetracyclines, giving examples
Following intake into susceptible organisms by active transport, tetracyclines act by inhibiting protein synthesis -> bind to bacterial ribosomes, preventing binding of tRNA to it, thus preventing the initiation of protein synthesis
Examples: doxycycline
Bacteriostatic
List indications and warnings for tetracyclines
Respiratory tract infections Acne Chlamydia Lyme disease Warning: shouldn’t be given to children <12 years, pregnant & breastfeeding women -> causes staining of developing teeth
Describe macrolides, giving examples
Inhibit bacterial protein synthesis by an effect on ribosomal translocation
Bactericidal/bacteriostatic
Examples: clarithromycin, azithromycin
Antimicrobial spectrum very similar to penicillin, also active against atypical respiratory pathogens
Describe the mechanism of action of nitrofurans
Works by being reduced to multiple reactive intermediates by nitrofuran reductase inside the bacterial cell
These intermediates then attack ribosomal and DNA proteins within the bacteria, as well as inhibit the citric acid cycle
Why is nitrofurantoin one of the first-line agents in treating UTIs?
Up to 50% of an oral dose nitrofurantoin is excreted in the urine in unchanged form
Allows nitrofurantoin to concentrate within urine, leading to more effective levels within the bladder than in other tissue compartments
Describe quinolones, giving examples
Inhibit topoisomerase II, the enzyme that produces a negative supercoil in DNA & thus permits transcription or replication
Common examples: ciprofloxacin
Good cover of gram negative organisms, as well as atypical organisms & gram positives
List indications and side effects of quinolones
Indications: complicated UTIs, pseudomonas aeruginosa, gonorrhoea
Side effects: tendinitis +/- rupture, aortic dissection, CNS effects
List antibacterial agents that interfere with folate synthesis or action
Sulfonamides
Trimethoprim