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Clinical Pathology (mine) > Intro to antimicrobial agents > Flashcards

Intro to antimicrobial agents Flashcards

1
Q

Define antibiotics

A

chemical products of microbes that inhibit or kill other organisms

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2
Q

What is covered by the term antimicrobial agents?

A

anitbiotics, synthetic compounds with similar effects, semi-synthetic compounds

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3
Q

Define BACTERISTATIC agents

A

inhibit bacterial growth (protein synthesis inhibitors)

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4
Q

Define BACTERIACIDAL agents

A

kill bacteria (cell wall-active agents)

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5
Q

What does MIC stand for?

A

Minimum inhibitory concentration

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6
Q

Define SYNERGISM

A

activity of two antimicrobials given together is greater than the sum of their activity if given separately

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7
Q

Define ANTAGONISM

A

one agent diminishes the activity of another

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8
Q

Define INDIFFERENCE

A

activity unaffected by the addition of another agent

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9
Q

What are the two mehcaniisms by which antibacterial agents work?

A

Inhibition of clinical process in bacterial cells and selective toxicity

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10
Q

How can selective toxicity be achieved? (2)

A

target not present in human host, or target significantly different in human host)

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11
Q

Give some examples of where antibiotics target

A

cell wall, protein synthesis, DNA synthesis, RNA synthesis, plasma membrane

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12
Q

What is the main component in the bacterial cell wall?

A

peptidoglycan

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13
Q

What are NAM and NAG?

A

N-acetyl muramic acid (NAM) and N-acetyl glucosamine (NAG)

polymers of glucose derivatives

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14
Q

Name 2 cell wall synthesis inhibitors

A

beta-lactams and glycopeptides

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15
Q

Which cell wall synthesis inhibitor is present in penicillin?

A

beta-lactams

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16
Q

Describe the common structure in all beta-lactams

A

‘beta-lactam ring’: four-membered ring structure (C-C-C-N), structural analogue of D-alanyl-D-alanine

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17
Q

What enzymes are involved in peptidoglycan cross-linking?

A

transpeptidases

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18
Q

Name the four main groups of beta-lactam antibiotics

A

penecillins, cephalosporins, carbapenems, monobactams

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19
Q

What is good about carbapenems?

A

Very broad spectrum

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20
Q

Which group of beta-lactams can be used safely in those with penicillin allergy?

A

Monobactams - aztreonam

21
Q

Which family of bacteria are glycopeptides effective on?

A

ONLY gram-positive

22
Q

What do the 50S and 30S subunits of ribosomes combine to form?

A

70S initiation complex

23
Q

How do aminoglycosides work?

A

protein synthesis inhibitor (bind to 30S subunit)

24
Q

What is the main side effect of gentamicin?

A

nephrotoxicity

25
Q

What does MLS stand for and how do they work?

A

macrolides, lincosamides, streptogramins: protein synthesis inhibitors (bind to 50S subunit to inhibit protein elongation)

26
Q

How to tetracyclines work?

A

protein synthesis inhibitors: bind to 30S ribosomal unit to inhibit RNA translation

27
Q

What is the action of oxazolidinones?

A

inhibits initiation of protein synthesis by binding to 50S subunit (can’t make initiation complex)

28
Q

How do trimethoprims and sulphonamides work?

A

DNA synthesis inhibitors

29
Q

How do quinolones and fluoroquinolones work?

A

DNA synthesis inhibitors: inhibit one or more of two related enzymes

30
Q

How does rifampicin work?

A

RNA synthesis inhibitor: RNA polymerase inhibitor

31
Q

Colistin and dapyomycin are plasma membrane agents of which bacterial families?

A

Colistin - gram-negative

daptomycin - gram-positive

32
Q

Which type of antibiotics cause most problems due to allergic reactions?

A

beta-lactams

33
Q

Are cephalosporins and carbapenems safe to use in patients with severe penicillin allergy?

A

NO - only safe in patients with a non-severe penicillin allergy

34
Q

Which beta-lactam can be used safely in patients with a severe penicillin allergy?

A

aztreonam

35
Q

Which strain of C. diff is hypervirulent?

A

027

36
Q

Which are the 4 common precipitating antiobiotics for C diff?

A

Co-amoxiclav, cephalosporins, ciprofloxacin, clindamycin

37
Q

Which antibiotic is most commonly used to treat staphylococcus aureus?

A

flucloxacillin

38
Q

Which antibiotic is commonly used to treat streptococcus pyogenes?

A

benzylpenicillin

39
Q

Which antibiotic is commonly used to treat gram-negative bacilli?

A

cephalosporins (avoid in elderly)

40
Q

Which antibiotic is commonly used to treat anaerobes?

A

metronidazole

41
Q

Which antibiotic is commonly used to treat gram-positives?

A

vancomycin

42
Q

Which antibiotic is commonly used to treat most clinically-relevant bacteria?

A

meropenem

43
Q

Which antibiotic is used as a last option for multi-resistant gram-negatives?

A

colistin

44
Q

What are the 2 main pharmacodynamics considerations?

A

concentration and time dependant

45
Q

Why is pharmacokinetic consideration important?

A

important determinant of in vivo efficacy is concentration at site of action

46
Q

How should a concentration dependant antibiotic be administered?

A

intermittently to achieve high peaks

47
Q

How should time dependant antibiotics be administered?

A

frequently to maintain high level

48
Q

What are the 3 reasons for combination therapy?

A

increase efficiacy, provide adequately broad spectrum, reduce resistance

Clinical Pathology (mine) (28 decks)

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