Antibiotics & Antimicrobial Stewardship

Question 1

How are antimicrobials classified?

Answer 1

Antibacterial, antifungal, antiviral and antiprotozoal agents

Question 2

How are antibacterials classified?

Answer 2

Bacteriocidal or bacteriostatic, broad or narrow, mechanism of action, chem structure

Question 3

What are the ideal features of antimicrobial agents?

Answer 3

Selectively toxic, few adverse effects, reach site of infect, oral/IV, long half-life, no interference with other drugs

Question 4

What are the mechanisms of antibiotics?

Answer 4

Inhibit cell wall synthesis, interrupt cell wall function, inhibit nucleic acid synthesis, inhibit protein synthesis

Question 5

Name a class of Abx that inhibits cell wall synthesis

Answer 5

Beta-lactams

Question 6

Name a of class of Abx that interrupt cell membrane function

Answer 6

Polymixins

Question 7

Name a class of Abx that inhibit nucleic acid synthesis

Answer 7

Quinolones

Question 8

Name a class of Abx that inhibit protein synthesis

Answer 8

Tetracyclines, aminoglycosides

Question 9

How is bacterial cell wall synthesis inhibited by Abx?

Answer 9

PBP blocked by Abx, or Abx blocks binding spot on cell wall for PBP

Question 10

How is nucleic acid synthesis inhibited by Abx

Answer 10

Quinolones bind topoisomerase/DNA gyrase inhibited DNA replication

Question 11

Outline how antibiotics stop bacterial protein synthesis

Answer 11

Abx interfere with the 30S + 50S ribosomes

Question 12

Describe how Abx interfere with cell membrane function

Answer 12

Disrupt structure = lysis

Question 13

What are the types of antimicrobial resistance

Answer 13

Intrinsic = no target/access for drug,

acquired = new genetic material,

adaptive = MO responds to stress

Question 14

What are the mechanisms of resistance?

Answer 14

Inactivating enzymes = beta-lactamases,

altered target = change of antigens,

altered uptake = efflux pumps

Question 15

What mechanisms enable antibiotic resistance to be acquired?

Answer 15

Horizontal gene transfer, vertical gene transfer = mother to daughter

Question 16

By what methods can horizontal gene transfer take place?

Answer 16

Conjugation = plasmid transfer,

transduction = viral delivery,

transformation = genetic material from dead bacteria

Question 17

How can the Abx sensitivity of a bacteria be measured?

Answer 17

Disc sensitivity testing,

MIC = minimum inhibitory testing

Question 18

Name and outline a combination Abx

Answer 18

Co-amoxiclav = amoxicillin + clavulanic acid = acids inhibits lactamases, amox = kills G -ve

Question 19

What are cephalosporins and how are they classified?

Answer 19

Beta-lactam Abx, 1st 2nd and 3rd generation = new gens have significantly greater G -ve antimicrobial properties

Question 20

When are penicillin’s used?

Answer 20

Staph, step,

Some activity for G –ve

Question 21

When are cephalosporins used?

Answer 21

G +ve and –ve, broad spec

Question 22

When are carbapenems used?

Answer 22

Broad spec, G –ve, safe in penicillin allergy, kills anaerobes

Question 23

Give an example of a glycopeptide and outline when it is used

Answer 23

Vancomycin = G +ve, requires therapeutic drug monitoring = small therapeutic window, some enterococci are resistant (VRE)

Question 24

When are tetracyclines used?

Answer 24

E.g. doxycycline: Broad spec, used in penicillin allergy, oral only, chlamydia and some protozoa

Question 25

When are aminoglycosides used?

Answer 25

E.g. gentamicin, G –ve therapeutic drug monitoring required, generally reserved for G –ve sepsis

Question 26

What is an example of a macrolide and when is it used?

Answer 26

Erythromycin: alternative to penicillin for mild G +ve, resp pathogens

Question 27

What is the most commonly used quinolone and how does it work?

Answer 27

Ciprofloxacin: inhibits DNA gyrase, G –ve

Question 28

What is used to treat UTIs?

Answer 28

Trimethoprim

Question 29

Name an antifungal and what it treats

Answer 29

Fluconazole: candida

Question 30

Name an antiviral, how it works and what it treats

Answer 30

Acyclovir = when phosphorylated inhibits viral DNA polymersse, herpes simplex

Question 31

What drug is both antibacterial and antiprotozoal

Answer 31

Metronidazole

Question 32

Describe the concept of antimicrobial stewardship

Answer 32

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

Question 33

Outline measures to take to ensure the appropriate use of antimicrobials

Answer 33

appropriate prescribing = only for bacterial infections, appropriate dose, appropriate length of course

Question 34

What are the consequences of antibacterial resistance?

Answer 34

treatment failure, prophylaxis failure, economic costs

Question 35

How can the level of antimicrobial resistance be classed?

Answer 35

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