Intro to antimicrobial agents

Question 1

Define antibiotics

Answer 1

chemical products of microbes that inhibit or kill other organisms

Question 2

What is covered by the term antimicrobial agents?

Answer 2

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

Question 3

Define BACTERISTATIC agents

Answer 3

inhibit bacterial growth (protein synthesis inhibitors)

Question 4

Define BACTERIACIDAL agents

Answer 4

kill bacteria (cell wall-active agents)

Question 5

What does MIC stand for?

Answer 5

Minimum inhibitory concentration

Question 6

Define SYNERGISM

Answer 6

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

Question 7

Define ANTAGONISM

Answer 7

one agent diminishes the activity of another

Question 8

Define INDIFFERENCE

Answer 8

activity unaffected by the addition of another agent

Question 9

What are the two mehcaniisms by which antibacterial agents work?

Answer 9

Inhibition of clinical process in bacterial cells and selective toxicity

Question 10

How can selective toxicity be achieved? (2)

Answer 10

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

Question 11

Give some examples of where antibiotics target

Answer 11

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

Question 12

What is the main component in the bacterial cell wall?

Answer 12

peptidoglycan

Question 13

What are NAM and NAG?

Answer 13

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

polymers of glucose derivatives

Question 14

Name 2 cell wall synthesis inhibitors

Answer 14

beta-lactams and glycopeptides

Question 15

Which cell wall synthesis inhibitor is present in penicillin?

Answer 15

beta-lactams

Question 16

Describe the common structure in all beta-lactams

Answer 16

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

Question 17

What enzymes are involved in peptidoglycan cross-linking?

Answer 17

transpeptidases

Question 18

Name the four main groups of beta-lactam antibiotics

Answer 18

penecillins, cephalosporins, carbapenems, monobactams

Question 19

What is good about carbapenems?

Answer 19

Very broad spectrum

Question 20

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

Answer 20

Monobactams - aztreonam

Question 21

Which family of bacteria are glycopeptides effective on?

Answer 21

ONLY gram-positive

Question 22

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

Answer 22

70S initiation complex

Question 23

How do aminoglycosides work?

Answer 23

protein synthesis inhibitor (bind to 30S subunit)

Question 24

What is the main side effect of gentamicin?

Answer 24

nephrotoxicity

Question 25

What does MLS stand for and how do they work?

Answer 25

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

Question 26

How to tetracyclines work?

Answer 26

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

Question 27

What is the action of oxazolidinones?

Answer 27

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

Question 28

How do trimethoprims and sulphonamides work?

Answer 28

DNA synthesis inhibitors

Question 29

How do quinolones and fluoroquinolones work?

Answer 29

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

Question 30

How does rifampicin work?

Answer 30

RNA synthesis inhibitor: RNA polymerase inhibitor

Question 31

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

Answer 31

Colistin - gram-negative | daptomycin - gram-positive

Question 32

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

Answer 32

beta-lactams

Question 33

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

Answer 33

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

Question 34

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

Answer 34

aztreonam

Question 35

Which strain of C. diff is hypervirulent?

Answer 35

027

Question 36

Which are the 4 common precipitating antiobiotics for C diff?

Answer 36

Co-amoxiclav, cephalosporins, ciprofloxacin, clindamycin

Question 37

Which antibiotic is most commonly used to treat staphylococcus aureus?

Answer 37

flucloxacillin

Question 38

Which antibiotic is commonly used to treat streptococcus pyogenes?

Answer 38

benzylpenicillin

Question 39

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

Answer 39

cephalosporins (avoid in elderly)

Question 40

Which antibiotic is commonly used to treat anaerobes?

Answer 40

metronidazole

Question 41

Which antibiotic is commonly used to treat gram-positives?

Answer 41

vancomycin

Question 42

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

Answer 42

meropenem

Question 43

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

Answer 43

colistin

Question 44

What are the 2 main pharmacodynamics considerations?

Answer 44

concentration and time dependant

Question 45

Why is pharmacokinetic consideration important?

Answer 45

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

Question 46

How should a concentration dependant antibiotic be administered?

Answer 46

intermittently to achieve high peaks

Question 47

How should time dependant antibiotics be administered?

Answer 47

frequently to maintain high level

Question 48

What are the 3 reasons for combination therapy?

Answer 48

increase efficiacy, provide adequately broad spectrum, reduce resistance