Antibiotics & Antimicrobial Stewardship Flashcards
How are antimicrobials classified?
Antibacterial, antifungal, antiviral and antiprotozoal agents
How are antibacterials classified?
Bacteriocidal or bacteriostatic, broad or narrow, mechanism of action, chem structure
What are the ideal features of antimicrobial agents?
Selectively toxic, few adverse effects, reach site of infect, oral/IV, long half-life, no interference with other drugs
What are the mechanisms of antibiotics?
Inhibit cell wall synthesis, interrupt cell wall function, inhibit nucleic acid synthesis, inhibit protein synthesis
Name a class of Abx that inhibits cell wall synthesis
Beta-lactams
Name a of class of Abx that interrupt cell membrane function
Polymixins
Name a class of Abx that inhibit nucleic acid synthesis
Quinolones
Name a class of Abx that inhibit protein synthesis
Tetracyclines, aminoglycosides
How is bacterial cell wall synthesis inhibited by Abx?
PBP blocked by Abx, or Abx blocks binding spot on cell wall for PBP
How is nucleic acid synthesis inhibited by Abx
Quinolones bind topoisomerase/DNA gyrase inhibited DNA replication
Outline how antibiotics stop bacterial protein synthesis
Abx interfere with the 30S + 50S ribosomes
Describe how Abx interfere with cell membrane function
Disrupt structure = lysis
What are the types of antimicrobial resistance
Intrinsic = no target/access for drug,
acquired = new genetic material,
adaptive = MO responds to stress
What are the mechanisms of resistance?
Inactivating enzymes = beta-lactamases,
altered target = change of antigens,
altered uptake = efflux pumps
What mechanisms enable antibiotic resistance to be acquired?
Horizontal gene transfer, vertical gene transfer = mother to daughter
By what methods can horizontal gene transfer take place?
Conjugation = plasmid transfer,
transduction = viral delivery,
transformation = genetic material from dead bacteria
How can the Abx sensitivity of a bacteria be measured?
Disc sensitivity testing,
MIC = minimum inhibitory testing
Name and outline a combination Abx
Co-amoxiclav = amoxicillin + clavulanic acid = acids inhibits lactamases, amox = kills G -ve
What are cephalosporins and how are they classified?
Beta-lactam Abx, 1st 2nd and 3rd generation = new gens have significantly greater G -ve antimicrobial properties
When are penicillin’s used?
Staph, step,
Some activity for G –ve
When are cephalosporins used?
G +ve and –ve, broad spec
When are carbapenems used?
Broad spec, G –ve, safe in penicillin allergy, kills anaerobes
Give an example of a glycopeptide and outline when it is used
Vancomycin = G +ve, requires therapeutic drug monitoring = small therapeutic window, some enterococci are resistant (VRE)
When are tetracyclines used?
E.g. doxycycline: Broad spec, used in penicillin allergy, oral only, chlamydia and some protozoa
When are aminoglycosides used?
E.g. gentamicin, G –ve therapeutic drug monitoring required, generally reserved for G –ve sepsis
What is an example of a macrolide and when is it used?
Erythromycin: alternative to penicillin for mild G +ve, resp pathogens
What is the most commonly used quinolone and how does it work?
Ciprofloxacin: inhibits DNA gyrase, G –ve
What is used to treat UTIs?
Trimethoprim
Name an antifungal and what it treats
Fluconazole: candida
Name an antiviral, how it works and what it treats
Acyclovir = when phosphorylated inhibits viral DNA polymersse, herpes simplex
What drug is both antibacterial and antiprotozoal
Metronidazole
Describe the concept of antimicrobial stewardship
coordinated program that promotes the appropriate use of antimicrobials (including antibiotics), improves patient outcomes, reduces microbial resistance, and decreases the spread of infections caused by multidrug-resistant organisms
Outline measures to take to ensure the appropriate use of antimicrobials
appropriate prescribing = only for bacterial infections, appropriate dose, appropriate length of course
What are the consequences of antibacterial resistance?
treatment failure, prophylaxis failure, economic costs
How can the level of antimicrobial resistance be classed?
MDR multi-drug res = non-sus to 1 agent in 3 or more antimicrobial categories.
XDR extensively drug res = non-sus to at least 1 agent in all but 2 or fewer categories.
PDR pan-drug res = non-sus to all
