Session 4 - Introduction To Antimicrobials And Resistance

Question 1

What are the 4 types of antimicrobial agents?

Answer 1

Antibacterial
Antifungal
Antiviral
Antiprotozoal

Question 2

What are 8 questions to ask when choosing an antibiotic?

Answer 2

Is it active against target organism?
Does it reach the site of infection?
Is it available in the right formation? 
What is the half life?
Does it interact with other drugs?
Is there toxicity issues?
Does it require monitoring?
Does your patient have allergies?

Question 3

What are the 3 ways to measure antibiotic activity?

Answer 3

Disc sensitivity testing
Minimum inhibitory concentration - broth microdilution
Minimum inhibitory concentration - epsilometer test

Question 4

What are the 3 types of antimicrobial resistance?

Answer 4

Intrinsic
Adaptive
Acquired

Question 5

What is intrinsic antimicrobial resistance?

Answer 5

Either no target or access for the drug

Question 6

What is acquired antimicrobial resistance?

Answer 6

Acquires new genetic material or mutates

Question 7

What is adaptive antimicrobial resistance?

Answer 7

Organism responds to a stress which induces the bacteria to switch on genes which confer resistance

Question 8

What are 3 mechanisms of resistance?

Answer 8

Enzymatic modification or destruction of antibiotics
Enzymatic alteration of antibiotic targets
Over expression of efflux pumps

Question 9

How does chromosomal gene mutations allow bacteria to become resistant?

Answer 9

One bacteria carrying mutation which confers resistance reproduces, so it outnumbers the ones that are not resistant

Question 10

How does horizontal gene transfer allow bacteria to become resistant?

Answer 10

Donor carrying plasmid with resistance grows a pillus, which extends to recipient and using a relaxasome, transferasome and DNA polymerase, recipient receives the resistant gene from the donor’s plasmid

Question 11

What does beta-lactate antibiotics interfere with?

Answer 11

Synthesis of bacterial cell wall peptidoglycan

Question 12

Are beta lacrimal antibiotics bactericidal or bacteriostatic?

Answer 12

Bactericidal

Question 13

How do beta-lactate antibiotics interfere with synthesis of cell wall?

Answer 13

Binds to penicillin-binding protein on bacteria, inhibits the trans peptidation enzyme, cannot link peptidoglycan chains to form rigid cell walls, disrupts bacterial cell wall structure

Question 14

What are 3 main sub groups of beta-lactam antibiotics?

Answer 14

Penicillins
Cephalosporins
Carbapenems

Question 15

What is penicillins derived from?

Answer 15

Penicillium notatum

Question 16

What is cephalosporins derived from?

Answer 16

Cephalosporium acreminium

Question 17

What are carbapenems?

Answer 17

Penicillin but with carbon atom instead of sulfur

Question 18

How does glycopeptide antibiotics work?

Answer 18

Inhibit cell wall synthesis

Question 19

How does glycopeptide antibiotics inhibit cell wall synthesis?

Answer 19

Blocks incorporation of NAG-NAM-PEP repeat unit in the growing peptidoglycan chains, preventing cell wall from growing

Question 20

What kind of bacteria is glycopeptide antibiotics used on?

Answer 20

Gram positive

Question 21

What are the 5 groups of antibacterial affecting bacterial protein synthesis?

Answer 21

Tetracyclines 
Aminoglycosides
Macrolides
Oxazolidinones
Lincosamides

Question 22

How do tetracyclines work?

Answer 22

Inhibit protein synthesis

Question 23

Are tetracyclines bactericidal or bacteriostatic?

Answer 23

Bacteriostatic

Question 24

How do tetracyclines inhibit protein synthesis?

Answer 24

Uptake into organism by active transport, binds to bacterial ribosomes, prevent binding of tRNA to it, preventing the initiation of protein synthesis

Question 25

What are the 3 groups of patients who should not be given tetracyclines and why?

Answer 25

Children under 12, Pregnant, Breastfeeding women bc they stain developing teeth

Question 26

How do aminoglycosides work?

Answer 26

Inhibit bacterial protein synthesis

Question 27

How do aminoglycosides inhibit bacterial protein synthesis?

Answer 27

Bind to bacterial ribosomal subunits, leading to misreading of mRNA, insert incorrect ammonia acids, loss of function

Question 28

What kind of bacteria are aminoglycosides usually used for?

Answer 28

Gram negative

Question 29

What is the role of macrolides?

Answer 29

Inhibit bacterial protein synthesis by an effect on ribosomal translocation

Question 30

What kind of bacteria is oxazolidinones used for?

Answer 30

Gram positive

Question 31

How do lincosamides act?

Answer 31

Inhibit bacterial protein synthesis by an effect on ribosomal translocation

Question 32

What kind of bacteria do lincosamides act on?

Answer 32

Gram +ve cocci

Question 33

How does quinolones act?

Answer 33

Inhibit bacteria replication

Question 34

How do quinolones inhibit replication?

Answer 34

Inhibit topoisomerase II which produces a negative supercoil in DNA, inhibiting transcription or replication

Question 35

What are 2 antibacterial agents that interfere with folate synthesis or action?

Answer 35

Sulfonamides | Trimethoprim

Question 36

How do sulfonamides work?

Answer 36

Metabolized into active product sulfanilamide, which is a structural analogue of PABA, which is needed to make folic acid, which is needed to synthesize DNA and RNA in bacteria, so it competes with PABA for enzyme dihydropteroate synthetase, decreasing production of folic acid

Question 37

Are sulfonamides bacteriostatic of bacteriocidic?

Answer 37

Bacteriostatic

Question 38

How does trimethoprim work?

Answer 38

Reversible inhibitor of dihydrofolate reductase, which produces tetrahydrofllkc acid needed to make bacterial nucleic acids and proteins

Question 39

What does metronidazole do?

Answer 39

Antiprotozoal agent but can target anaerobic bacteria too

Question 40

What are 2 groups of anti fungals?

Answer 40

Azoles | Polyenes

Question 41

What do azoles do?

Answer 41

Inhibit fungal cytochrome P450 3A enzyme to prevent formation of Ergosterol which interferes with action of membrane associated enzymes, inhibiting repLication

Question 42

What do azoles treat?

Answer 42

Candida infections

Question 43

What is the site of action of polyenes and what do they do?

Answer 43

Fungal cell membrane, lodge in the cell wall and cause leaking, altering cellular permeability

Question 44

What are 2 common uses of antivirals?

Answer 44

Aciclovir | Oseltamivir

Question 45

What do aciclovir do?

Answer 45

Activated in infected cells, viral enzyme thymidine kinase is more effective at phosphorylation it thus activating it, it inhibits viral DNA polymerase

Question 46

What does oseltamivir do?

Answer 46

Severes bonds linking particle coat and host sialic acid which alllws newly replicated visions to escape from host cells by budding from cell membrane

Question 47

What are 3 consequences of antibacterial resistance?

Answer 47

Treatment failure Prophylaxis failure Economic costs

Question 48

What is multi drug resistant?

Answer 48

Non susceptibility to at least one agent in 3 or more antimicrobial categories

Question 49

What is extensively drug resistant?

Answer 49

Non susceptible to at least one agent in all but 2 or fewer antimicrobial categories

Question 50

What is pan drug resistant?

Answer 50

Not susceptible to all agents in all antimicrobial categories

Question 51

What is antimicrobial stewardship?

Answer 51

Coordinates interventions designed to improve and measure the appropriate use of antimicrobial by promoting the selection of optimal antimicrobial drug regimen, dose, duration of therapy and route of administration

Question 52

What are 4 objectives of antimicrobial stewardship?

Answer 52

Optimal clinical outcomes Minimize toxicity and other adverse events Reduce costs of healthcare for infections Limit selection for antimicrobial resistant strains