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Infection > Session 4 - Introduction To Antimicrobials And Resistance > Flashcards

Session 4 - Introduction To Antimicrobials And Resistance Flashcards

1
Q

What are the 4 types of antimicrobial agents?

A

Antibacterial
Antifungal
Antiviral
Antiprotozoal

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2
Q

What are 8 questions to ask when choosing an antibiotic?

A 
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?
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3
Q

What are the 3 ways to measure antibiotic activity?

A

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

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4
Q

What are the 3 types of antimicrobial resistance?

A

Intrinsic
Adaptive
Acquired

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5
Q

What is intrinsic antimicrobial resistance?

A

Either no target or access for the drug

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6
Q

What is acquired antimicrobial resistance?

A

Acquires new genetic material or mutates

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7
Q

What is adaptive antimicrobial resistance?

A

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

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8
Q

What are 3 mechanisms of resistance?

A

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

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9
Q

How does chromosomal gene mutations allow bacteria to become resistant?

A

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

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10
Q

How does horizontal gene transfer allow bacteria to become resistant?

A

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

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11
Q

What does beta-lactate antibiotics interfere with?

A

Synthesis of bacterial cell wall peptidoglycan

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12
Q

Are beta lacrimal antibiotics bactericidal or bacteriostatic?

A

Bactericidal

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13
Q

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

A

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

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14
Q

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

A

Penicillins
Cephalosporins
Carbapenems

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15
Q

What is penicillins derived from?

A

Penicillium notatum

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16
Q

What is cephalosporins derived from?

A

Cephalosporium acreminium

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17
Q

What are carbapenems?

A

Penicillin but with carbon atom instead of sulfur

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18
Q

How does glycopeptide antibiotics work?

A

Inhibit cell wall synthesis

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19
Q

How does glycopeptide antibiotics inhibit cell wall synthesis?

A

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

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20
Q

What kind of bacteria is glycopeptide antibiotics used on?

A

Gram positive

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21
Q

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

A 
Tetracyclines 
Aminoglycosides
Macrolides
Oxazolidinones
Lincosamides
22
Q

How do tetracyclines work?

A

Inhibit protein synthesis

23
Q

Are tetracyclines bactericidal or bacteriostatic?

A

Bacteriostatic

24
Q

How do tetracyclines inhibit protein synthesis?

A

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

25
Q

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

A

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

26
Q

How do aminoglycosides work?

A

Inhibit bacterial protein synthesis

27
Q

How do aminoglycosides inhibit bacterial protein synthesis?

A

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

28
Q

What kind of bacteria are aminoglycosides usually used for?

A

Gram negative

29
Q

What is the role of macrolides?

A

Inhibit bacterial protein synthesis by an effect on ribosomal translocation

30
Q

What kind of bacteria is oxazolidinones used for?

A

Gram positive

31
Q

How do lincosamides act?

A

Inhibit bacterial protein synthesis by an effect on ribosomal translocation

32
Q

What kind of bacteria do lincosamides act on?

A

Gram +ve cocci

33
Q

How does quinolones act?

A

Inhibit bacteria replication

34
Q

How do quinolones inhibit replication?

A

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

35
Q

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

A

Sulfonamides

Trimethoprim

36
Q

How do sulfonamides work?

A

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

37
Q

Are sulfonamides bacteriostatic of bacteriocidic?

A

Bacteriostatic

38
Q

How does trimethoprim work?

A

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

39
Q

What does metronidazole do?

A

Antiprotozoal agent but can target anaerobic bacteria too

40
Q

What are 2 groups of anti fungals?

A

Azoles

Polyenes

41
Q

What do azoles do?

A

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

42
Q

What do azoles treat?

A

Candida infections

43
Q

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

A

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

44
Q

What are 2 common uses of antivirals?

A

Aciclovir

Oseltamivir

45
Q

What do aciclovir do?

A

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

46
Q

What does oseltamivir do?

A

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

47
Q

What are 3 consequences of antibacterial resistance?

A

Treatment failure
Prophylaxis failure
Economic costs

48
Q

What is multi drug resistant?

A

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

49
Q

What is extensively drug resistant?

A

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

50
Q

What is pan drug resistant?

A

Not susceptible to all agents in all antimicrobial categories

51
Q

What is antimicrobial stewardship?

A

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

52
Q

What are 4 objectives of antimicrobial stewardship?

A

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

Infection (11 decks)

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