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Week 6 - Clinical Microbiology & Infections 1 > Antibiotics 1 > Flashcards

Antibiotics 1 Flashcards

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1
Q

Describe the characteristic structures of gram-positive bacterium [2]

A
  1. thin cell membrane
  2. thick peptidoglycan cell wall
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2
Q

Describe the characteristics structures of gram-negative bacterium [4]

A
  1. thin cell membrane
  2. thin peptidoglycan cell wall
  3. thick periplasm
  4. outer membrane
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3
Q

What is a periplasm? [1]

A

concentrated gel-like matrix in the space between the inner cytoplasmic membrane and the outer membrane of the bacteria

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4
Q

What do antibiotics tend to target on a bacterium? [4]

A
  1. cell wall peptidoglycan
  2. metabolism
  3. DNA
  4. ribosome
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5
Q

What are the 2 types of antibiotics (classifed in terms of action)? [2]

A
  1. bactericidial antibiotics
  2. bacteriostatic antibiotics
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6
Q

How do bactericidal antibiotics work? [2]

A
  1. Achieve sterilisation of the infected site by directly killing bacteria
  2. Lysis of bacteria can lead to release of toxins and inflammatory material
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7
Q

How do bacteriostatic antibiotics work? [2]

A
  1. Suppresses growth but does not directly sterilise infected site
  2. Requires additional factors to clear bacteria → immune mediated killing
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8
Q

Define the term: antibiotic spectrum [1]

A

The range of bacterial species effectively treated by the antibiotic

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9
Q

What are the features of broad spectrum antibiotics? [2]

  • hints:
    • definition?
    • function?
A
  1. Antibiotics that are active against a wide range of bacteria
  2. Treat most causes of infection but also have a substantial effect on colonising bacteria
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10
Q

What are the features of narrow spectrum antibiotics? [3]

  • hint:
    • definition?
    • when is it useful?
    • limitations?
A
  1. Antibiotics that are active against a limited range of bacteria
  2. Useful only where the cause of the infection is well defined
  3. Have a much more limited effect on colonising bacteria
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11
Q

Give examples of gram negative bacteria [5]

A
  1. pseudomonas
  2. haemophilus
  3. neisseria
  4. other coliforms
  5. E. coli
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12
Q

Give examples of gram positive bacteria [3]

A
  1. staphylococcus
  2. enterococcus
  3. streptococcus
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13
Q

Give examples of anaerobes [2]

A
  1. clostridium
  2. bacteroides
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14
Q

What are the 3 types of antibiotic therapies? [3]

A
  1. guided therapy
  2. empirical therapy
  3. prophylactic therapy
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15
Q

What is guided therapy? [1]

  • hint: what is it dependent on?
A

Depends on identifying cause of infection and selecting agent based on sensitivity testing

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16
Q

What is empirical therapy? [2]

  • hint:
    • definition?
    • when is it used?
A
  1. Best (educated) guess therapy based on clinical/epidemiological acumen
  2. Used when therapy cannot wait for culture
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17
Q

What is prophylactic therapy? [1]

A

preventing infection before it begins

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18
Q

What are the types of antibiotic associated harm? [2]

A
  1. disruption of bacterial flora
  2. development of C. difficile colitis
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19
Q

Overgrowth of bacterial flora with yeasts can lead to…? [1]

A

thrush

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20
Q

Overgrowth of bacterial flora of the bowel can lead to…? [1]

A

diarrhoea

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21
Q

What type of antibiotic is used for guided therapy? Narrow spectrum or broad spectrum? [1]

A

narrow spectrum antibiotic

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22
Q

What type of antibiotic is used for empirical therapy? Narrow spectrum or broad spectrum antibiotics? [1]

A

broad spectrum antibiotic

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23
Q

What are the 5 types of β-lactam antibiotics? [5]

A
  1. Penicillin
  2. Cephalosporins
  3. Carbapenems
  4. Monobactams
  5. β-lactam/β-lactamase inhibitor combinations
24
Q

Give 3 examples of penicillin (β-lactam antibiotics) [3]

A
  1. Benzylpenicillin
  2. Flucloxacillin
  3. Amoxicillin
25
Q

Give an example of cephalosporins (β-lactam antibiotics) [1]

A

Ceftriaxone

26
Q

Give an example of carbapenems (β-lactam antibiotics) [1]

A

meropenem

27
Q

Give an example of monobactams (β-lactam antibiotics) [1]

A

aztreonam

28
Q

Give 2 examples β-lactam/β-lactamase inhibitor combinations [2]

A
  1. co-amoxiclav
  2. piperacillin/tazobactam
29
Q

Describe the mechanism of action of ß-lactam antibiotics [4]

A

all ß-lactams share the same branching structure of peptidoglycan which acts to inhibit crosslinking of cell wall peptidoglycan leading to lysis of bacteria

  • it is bacteriostatic
30
Q

Define beta-lactamases [1]

A

enzymes that lyse and inactivate beta-lactam drugs

31
Q

Which organisms commonly secrete beta-lactamases? [2]

A
  1. gram -ve bacteria
  2. S. aureus
32
Q

What is the complication beta-lactamase secretion? [1]

A

high level resistance to antibiotic (usually total antibiotic failure)

33
Q

How are ß-lactam antibiotics typically administered? [2]

A
  1. most are given intravenously (IV)
  2. some can be given orally
    • amoxicillin
    • flucloxacillin
    • however vomiting limits dose
34
Q

How are ß-lactam antibiotics usually excreted? [2]

A
  • Usually excreted unchanged in urine
  • Some also via bile
35
Q

What is the half-life of the β-lactam: benzylpenicillin? [1]

A

1 hour

36
Q

What is the half-life of the β-lactam: ceftriaxone? [1]

A

8 hours

37
Q

What are the potential GI toxicity adverse effects of β-lactam antibiotics? [3]

A
  1. nausea/vomiting
  2. diarrhoea
  3. cholestasis
38
Q

What are the potential hypersensitivity adverse effects of β-lactam antibiotics? [3]

A
  1. type 1 hypersensitivity
    • urticaria
    • anaphaylaxis
  2. type 4 hypersensitivity
    • mild to severe dermatology
  3. interstitial nephritis
39
Q

What are the potential infection adverse effects of β-lactam antibiotics? [2]

A
  1. candidiasis (oral/vulvovaginal)
  2. clostridium difficle infection
40
Q

What are the miscellaneous rare adverse effects of β-lactam antibiotics? [3]

A
  1. seizure
  2. haemolysis
  3. leukopaenia
41
Q

What is a urticarial rash? [1]

A

raised, itchy rash that appears on the skin in type 1 hypersensitivity

42
Q

How is benzylpenicillin typically administered? [1]

A

via IV

43
Q

What type of agent is benzylpenicillin?

Narrow spectrum or broad spectrum? [1]

A

narrow spectrum antibiotic

44
Q

Which bacteria are benzylpenicillin effective at targeting (incl. which class each bacteria is in)? [3]

A
  1. Streptococcus = gram +ve
  2. Neisseria = gram - ve
  3. Clostridium = anaerobe
45
Q

How is amoxicillin administered? [1]

A

orally

46
Q

Which bacteria are amoxicillin effective at targeting (incl. which class each bacteria is in)? [5]

A
  1. Streptococcus = gram +ve
  2. Enterococcus = gram +ve
  3. Neisseria = gram -ve
  4. Haemophilus = gram -ve
  5. Clostridium = anaerobe
47
Q

What is unique about flucloxacillin? [1]

A

it is a synthetic penicillin developed to be resistant to beta-lactamase produced by staphylococci

48
Q

Which bacteria are flucloxacillin effective at targeting (incl. which class each bacteria is in)? [2]

A
  1. Staphylococcus aureus (except MRSA) = gram +ve
  2. Streptococci = gram +ve
49
Q

Beta-lactamase inhibitors are combination drugs that are often co-admininstered with penicillin

Name 2 beta-lactamase inhibitors and state which drugs each are made of [4]

A
  1. Clavulanic acid & amoxicillin = co-amoxiclav
  2. Tazobactam & piperacillin = tazocin
50
Q

Which bacteria are co-amoxiclav effective at targeting (incl. which class each bacteria is in)? [9]

A
  1. Streptococcus = gram +ve
  2. Enterococcus = gram +ve
  3. Staphylococcus = gram +ve
  4. Neisseria = gram -ve
  5. Haemophilus = gram -ve
  6. E. coli = gram -ve
  7. Other coliforms = gram -ve
  8. Clostridium = anaerobe
  9. Bacteroides = anaerobe
51
Q

Ceftriaxone is 3rd gen. cephalosporin antibiotic.

Which bacteria are ceftriaxone effective at targeting (incl. which class each bacteria is in)? [8]

A
  1. Streptococcus = gram +ve
  2. Staphylococcus (except MRSA) = gram +ve
  3. E. coli = gram -ve
  4. Neisseria = gram -ve
  5. Haemophilus = gram -ve
  6. Other coliforms = gram -ve
  7. Clostridium = anaerobes
  8. Bacteroides = anaerobes
52
Q

Aztreonam is the only monobactam antibiotic out there.

Which bacteria are aztreoname effective at targeting (incl. which class each bacteria is in)? [5]

A
  1. E. coli = gram -ve
  2. Neisseria = gram -ve
  3. Haemophilus = gram -ve
  4. Pseudomonas = gram -ve
  5. Other coliforms = gram -ve
53
Q

Describe the mechanism of action of vancomycin [1]

A

Inhibits cell wall formation in Gram +ves only

54
Q

How is vancomycin typically administered? [1]

A

administered intravenously (IV)

55
Q

Which bacteria are vancomycin effective at targeting (incl. which class each bacteria is in)? [4]

A
  1. Streptococcus = gram +ve
  2. Staphylococcus = gram +ve
  3. Enterococcus = gram +ve
  4. Clostridium = anaerobe
56
Q

What are the potential complications of vancomycin toxicity? [3]

A
  1. Nephrotoxicity → more likely with higher doses
  2. Red-man syndrome
    • Occurs if injected too rapidly
      • Anaphylactoid reaction
      • Very rare now infusion rates slow
  3. Ototoxicity (rare)

Week 6 - Clinical Microbiology & Infections 1 (13 decks)

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