Cell Wall Synthesis Inhibitors

Question 1

Do beta lactams exhibit time or concentration dependent killing?

Answer 1

Time-dependent

Question 2

What is the mechanism of action of beta-lactams?

Answer 2

1. Binds to penicillin-binding proteins in the bacterial cell wall.
2. Inhibits transpeptidase enzymes that cross-link peptidoglycan chains that form cell walls
3. Activate autolytic enzymes causing lesions in cell wall

Question 3

List the 4 ways penicillins can become resisitant.

Answer 3

1. Beta-lactamase inactivation of antibiotic.
2. Alteration in PBPs
3. Reduction in outer membrane permeability.
4. Presence of efflux pump. (Gram -ve organisms)

Question 4

What was the original formulation available?

Answer 4

Benzylpenicillin (also called Pencillin G)

Question 5

What is the spectrum of activity for penicillins?

Answer 5

Gram positive aerobes (strepococcus species)
Gram negative aerobes (neisseria sp.)
C. Tetani, C. Perfringens

Question 6

List 4 uses of penicillins

Answer 6

Listeria, Syphillis, Pneumoccocal infections, anaerobes, diphtheria anthrax

Question 7

What are examples of 2nd generation penicillins

Answer 7

Ampicillin - Parenteral only
Amoxicillin - oral & parenteral only

Question 8

What is the spectrum of activity for 2nd generation agents?

Answer 8

Same as Pen G for Gram +. Gram -, SHEPS with Beta-lactamase inhibitors

Question 9

What are common uses of second generation aminopenicillins?

Answer 9

Lower RTIs, URTIs, UTIs, Meningitis

Question 10

List the gaps in the spectrum of 2ndary agents?

Answer 10

Klebsiella spp., Enterobacter spp., P aeruginosa, Citrobacter spp., Proteus spp.

Question 11

What are examples of anti-staphylococcal Beta-lactamse resistant penicillins

Answer 11

Cloxacillin, Oxacillin, Flucloxacillin. Spectrum of activity is staph aureus.

Question 12

What about the pharmacokinetics of 2ndary agents?

Answer 12

Food interferes with absorption, so take 2 hours before/after food.

Question 13

What is an example of a 4th generation agent?

Answer 13

Piperacillin. Exhibits significant activity against g-ve bacilli. Used in combination with tazobactam.

Question 14

List 4 adverse effects of CWSI.

Answer 14

Allergic or Hypersensitivity reactions, GI disturbances, Neurotoxity, Secondary reactions (candidasis)

Question 15

What happens if a anaphylactic allergic reaction occurs

Answer 15

Stop penicillin, assess reaction and give adrenaline