Y Lecture 1: Anti-Microbial Agents 1

Question 1

What is the broad mechanism of action of beta lactams?

Answer 1

Inhibition of cell wall synthesis

Question 2

What is the broad mechanism of action of glycopeptide antibiotics?

Answer 2

Inhibition of cell wall synthesis

Question 3

What 3 groups of antibiotics are classified as beta lactams?

Answer 3

Penicillins
Cephalosporins
Carbapenems

Question 4

Name 2 glycopeptide antibiotics

Answer 4

Vancomycin
Teicoplanin

Question 5

Describe the mechanism of action of beta lactams

Answer 5

Inhibits transpeptidase, which is an enzyme that forms cross links during the formation of the cell wall. The resulting cell wall is therefore weak, and so the bacteria lyse because of osmotic pressure.

Question 6

How does the cell wall of gram pos and gram neg bacteria differ?

Answer 6

Gram pos has peptidoglycan

Question 7

What bacteria is penicillin active against?

Answer 7

Gram pos

Question 8

What bacteria is amoxicillin active against?

Answer 8

Broad spectrum: gram pos and many gram neg

Question 9

Is streptococci gram pos or neg?

Answer 9

Gram pos

Question 10

Which beta lactam antibiotic is effective against pseudomonas?

Answer 10

Piperacillin

Question 11

How can beta lactam resistance be overcome?

Answer 11

Include a beta lactamase inhibitor
Eg. Clavulanic acid + amoxicllin (in co-amoxiclav)

Question 12

Is pseudomonas gram pos or gram neg?

Answer 12

Gram neg

(Pseudo”moan”as - ‘moan’ = negative)

Question 13

Is neisseria meningitis gram pos or gram neg?

Answer 13

Gram neg

(Neisseria starts with N = negative)

Question 14

Recall an antibiotic that is associated with C. difficile

Answer 14

Ceftriaxone (cephalosporin)

Question 15

Which beta lactam antibiotics are stable to ESBL organisms?

Answer 15

Carbapenems

Question 16

Recall a caution of beta lactam antibiotic

Answer 16

Excreted renally so reduce dose if renal impairment

Question 17

What type of bacteria are glycopeptides effective against?

Answer 17

Gram pos only - they are large molecules so can’t penetrate gram neg cell wall

Question 18

What are glycopeptides particularly useful for?

Answer 18

MRSA infection

Question 19

What is a caution of glycopeptide antibiotics?

Answer 19

They are nephrotoxic

Question 20

Recall the broad mechanism of action of glycopeptide antibiotics

Answer 20

Prevent peptide cross links in cell wall

Question 21

Recall the broad mechanism of action of aminoglycosides

Answer 21

Bind to 30s ribosomal subunit, preventing elongation of polypeptide chain

Question 22

Recall 2 examples of aminoglycoside antibiotics

Answer 22

gentamicin

amikacin

Question 23

What type of bacteria are aminoglycoside antibiotics effective against?

Answer 23

Gram neg

Question 24

Recall 2 toxicities of aminoglycosides

Answer 24

Ototoxicity
Nephrotoxicity

Question 25

What type of bacteria are macrolides effective against?

Answer 25

Gram pos

Question 26

What are macrolides particularly useful for?

Answer 26

Mild staph or strep infections in patients who are allergic to penicillin

Question 27

Recall 2 macrolide antibiotics

Answer 27

Azithromycin Clarithromycin

Question 28

Recall the broad mechanism of action of macrolides

Answer 28

Bind to the 50s subunit of ribosomes

Question 29

Recall a class of antibiotic you should never give to children or pregnant women

Answer 29

Tetracyclines

Question 30

Recall one side effect of tetracycline antibiotics

Answer 30

Light-sensitive rash

Question 31

What type of bacteria are tetracylines effective against?

Answer 31

They are broad spectrum

Question 32

Recall the broad mechanism of action of tetracyclines

Answer 32

Bind to 30s subunit of ribosomes

Question 33

What type of bacteria is chloramphenicol effective against?

Answer 33

Many - it is v broad spectrum

Question 34

Why is chloramphenicol rarely used?

Answer 34

Risk of aplastic anaemia and grey baby syndrome in neonates due to inability to metabolise drug

Question 35

Recall 2 specific bacteria that macrolides are effective against

Answer 35

Campylobacter sp Legionella pneumophila (macrolides = erythromycin/ azithromycin/ clarithromycin)

Question 36

Recall the broad mechanism of action of chloramphenicol

Answer 36

Binds to 50s subunit of ribosomes - inhibits formation of peptide bonds during translation

Question 37

Recall the broad mechanism of action of oxazolidinones

Answer 37

Binds to the 23s and 50s subunit of ribosomes to prevent 70s subunit formation

Question 38

Recall two types of bacteria that oxazolidinones are particularly active against

Answer 38

MRSA and VRE

Question 39

Recall an example of oxazolidinones

Answer 39

Linezolid

Question 40

Recall one potential side effect of oxazolidinones

Answer 40

Thrombocytopaenia

Question 41

Recall the broad mechanism of action of fluoroquinolones

Answer 41

Act on alpha subunit of DNA gyrase

Question 42

Recall 4 uses of fluoroquinolones

Answer 42

* UTI * Pneumonia * Atypical pneumonia * Bacterial gastroenteritis

Question 43

Recall 2 examples of fluoroquinolone antibiotics

Answer 43

* Levofloxacin * Moxifloxacin

Question 44

Give an example of a nitromidazole antibiotic

Answer 44

Metronidazole

Question 45

Recall types of organisms that metronidazole is effective against

Answer 45

Anaerobes Protozoa

Question 46

When should metronidazole be taken?

Answer 46

Right after visiting the toilet as it sits in bladder

Question 47

Recall the broad mechanism of action of rifampicin

Answer 47

Binds to DNA-dependent RNA polymerase to inhibit RNA synthesis

Question 48

Recall the main use of rifampicin

Answer 48

TB treatment

Question 49

Recall one side effect of rifampicin

Answer 49

Turns secretions orange

Question 50

Recall one condition of rifampicin prescription

Answer 50

Should never be prescribed alone as resistance develops very quickly

Question 51

Colistin is very toxic. Why is it coming back into use?

Answer 51

It is active agianst certain multi-drug resistant bacteria

Question 52

What is daptomycin licensed for the treatment of?

Answer 52

MRSAVRE

Question 53

Recall the 2 classes of antibiotic that inhibit folate synthesis

Answer 53

Sulphonamides Diaminopyrimidines

Question 54

Give an example of a sulphonamide

Answer 54

Trimethoprim

Question 55

What is the main use of trimethoprim

Answer 55

Uncomplicated UTI

Question 56

What are the 4 main mechanisms of resistance

Answer 56

1. Inactivation (eg beta latamases) 2. Altered target (so antibiotic no longer binds - important in MRSA where bacteria change the penicillin-binding protein, and in protein-synthesis inhibitors where the binding of the ribosome subunit is prevented) 3. Reduced accumulation(most important in gram negs - either due to efflux or to reduced uptake) 4. Bypass(particularly important for folate inhibitors - bacteria can change the enzyme they use)

Question 57

Which antibiotic is best for treating pseudomonas jirovecii?

Answer 57

Co-trimoxazole

Question 58

What is the broad mechanism of action of nirtromidazoles?

Answer 58

Inhibit DNA synthesis

Question 59

Which bacteria typically forms "gram pos cocci in clusters"?

Answer 59

Staphylococcus

Question 60

Which bacteria typically forms "gram pos cocci in chains"?

Answer 60

StreptococcusStrep sounds like 'stripe' = chain

Question 61

What gram stain status are enterococci?

Answer 61

Positive("Enter-o-coccus" = like letting someone in, positive thing to do)

Question 62

Is haemophilus gram pos or neg?

Answer 62

Gram negHa"emo"philus - emo = negative

Question 63

Is listeria gram pos or neg?

Answer 63

PositiveLister = good man = positive