Antibiotics Flashcards

1
Q

Resistant enterobacteriaceae

A

Esp E. coli and K. pneumoniae

  • Extended spectrum beta-lactamase (ESBL) producers - Carbapenemase producing enterobacteriaceae (CPE)
  • Kiebsiella producing carbapenemases (KPC)
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2
Q

Antimicrobial stewardship

A
  • The long-term effects of antimicrobial selection, dosage, and duration of treatment on resistance development should be a part of every antimicrobial treatment decision
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3
Q

Amoxicillin

A

Amoxicillin is a penicillin. Specifically it is an aminopenicillin (good oral bioavailability, longer half-life than penicillin V, better activity against some Gram negative bacteria)

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4
Q

What is amoxicillin used to treat

A

It is used in the treatment of S. pyogenes infections (sore throat, skin infections), pneumococcal infections (respiratory tract) and coliform infections (urinary tract infection).

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5
Q

Amoxicillin mechanism of action

A

Inhibition of bacterial cell wall synthesis

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6
Q

Amoxicillin adverse effects

A
  • Allergy

- Damage to commensal microflora

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7
Q

Amoxicillin standard dose

A

250-1000mg 8 hourly

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8
Q

Amoxicillin oral bioavailability

A

good

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9
Q

Amoxicillin half-life

A

1 hr

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10
Q

Amoxicillin excretion

A

urine

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11
Q

Amoxicillin interactions

A

Can increase levels of other protein bound drugs

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12
Q

Sore throat infection

A

Amoxicillin

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13
Q

Common side effect of penicillins in a patient with glandular fever

A
  • Giving penicillins can cause a rash
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14
Q

Pseudomonas treatment

A
  • Piperacillin anti-pseudomonas antibiotic
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15
Q

Penicillin allergy classification

A

Immediate/accelerated - type 1(0.02% of courses)

Delayed - mixed mechanisms (2-3% of courses)

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16
Q

Penicillin allergy - immediate/accelerated - type 1

A
  • 0-72 hrs after exposure
  • IgE mediated, mast-cell mediated
  • Urticaria, wheeze, life threatening
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17
Q

Penicillin allergy - delayed mechanisms(2-3% of courses)

A

> 72 hrs after exposure

  • Will worsen with repeated exposure
  • Does not become immediate type
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18
Q

Cephalosporin allergy

A

Very complicated - lots of potential haptens involved
- Not a class effect
- Penicillin X-reactivity more with 1st and 2nd generations
Risk - 8% if previous penicillin allergy
- Less with 3rd generation

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19
Q

Clarythromycin

A
  • Is a similar spectrum of action to amoxicillin and is used for patients with penicillin allergy
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20
Q

What is clarythromycin used to treat

A

Treatment of S.pyogenes infections(sore throat, skin infections), pneumococcal infections(resp tract) and coliform infections(urinary tract infection)

  • Also active against cell-wall deficient bacteria(e.g. chlamydia) which cause penumonia and genitourinary infections
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21
Q

Clarythromycin mechanism of action

A
  • Inhibition of protein synthesis in the bacterial ribosome (50S subunit)
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22
Q

Clarythromycin - oral bioavailability

A

good

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23
Q

Clarythromycin - metabolism

A

hepatic

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24
Q

Clarythromycin - excretion and halflife

A

Half-life - 1-6 hrs

25
Q

Clarythromycin - standard dose

A

500mg

12 hrly

26
Q

Clarythromycin - adverse effects

A
  • Nausea and diarrhoea

- May alter cardiac conduction –> arrhythmias

27
Q

Clarythromycin interactions

A
  • Inhibits enzymes (cytochrome p450 enzymes) involved in the metabolism of other drugs
28
Q

Vancomycin

A
  • Is a glycopeptide

- Is active only against gram-positive bacteria and is active against many resistant strains including MRSA

29
Q

Vancomycin mechanism of action

A
  • Inhibits bacterial cell wall (peptidoglycans) formation by a different target to beta lactams
30
Q

Vancomycin standard dose

A

500-1500mg 12 hourly
Narrow therapeutic window
Dose by drug levels in blood

31
Q

Vancomycin oral bioavailability

A

Very low

32
Q

Vancomycin metabolism

A

None

33
Q

Vancomycin half-life

A

4-8 hrs

34
Q

Vancomycin excretion

A

urine

35
Q

Vancomycin adverse effects

A

Nephrotoxic

Ototoxic

36
Q

Vancomycin interactions

A

Other ototoxic or nephrotoxic drugs

37
Q

When is vancomycin administered orally

A
  • C.diff
38
Q

Doxycycline

A
  • Tetracycline
39
Q

What is doxycycline effective against

A
  • Good activity against gram positives (streps and staphs) some gram negs (haemophilus)
  • Also active against cell-wall deficient bacteria(e.g. chlamydia)
  • Used for skin, resp tract, genital tract infections
40
Q

Doxycycline mechanism of action

A
  • Inhibition of protein synthesis in the bacterial ribosome(30S subunit)
41
Q

Doxycycline standard dose

A

100-200mg daily

42
Q

Doxycycline oral bioavailability

A

good

43
Q

Doxycycline metabolism

A

None

44
Q

What is doxycycline poor against

A

Poor against enterobacteriaceae, anaerobes

45
Q

Doxycycline half-life

A

6-12 hrs

46
Q

Doxycycline excretion

A

urine and bile

47
Q

Doxycycline adverse effects

A

Dyspepsia
Photosensitivity
Avoid in pregnancy/children (teeth)

48
Q

Doxycycline interactions

A
  • Competes for protein binding

- Warfarin, digoxin etc

49
Q

What is nitrofurantoin used for

A

Wide spectrum - esp E. coli and some other enterobacteriaceae, also enterococci, staphs, some streps

50
Q

Nitrofurantoin mechanism of action

A
  • Complex
  • Damages bacterial DNA
  • High resistance threshold?
51
Q

Nitrofurantoin excretion

A

urine

52
Q

Nitrofurantoin metabolism

A

none

53
Q

Nitrofurantoin half-life

A

1 hr

54
Q

Nitrofurantoin oral bioavailability

A

good

55
Q

Nitrofurantoin standard dose

A

50mg qds

56
Q

Nitrofurantoin adverse effects

A

V well tolerated
Safe in early pregnancy - avoid late
Avoid in renal impairment - peripheral neuropathy, doesn’t penetrate urine if eGFR low

57
Q

Nitrofurantoin interactions

A
  • No major issues
58
Q

What is nitrofurantoin the first line antibiotic for

A
  • UTIs
59
Q

Nitrofurantoin interactions

A
  • No major issues