Beta-Lactams

Question 1

Are beta-lactams water soluble or lipid soluble?

Answer 1

Water soluble, and therefore they tend to stay in the extracellular space.

Question 2

How do beta-lactams work?

Answer 2

Inhibit bacterial cell wall synthesis and prevents peptidoglycan cross-linkage.

Question 3

Are beta-lactams bactericidal or bacteriostatic?

Answer 3

Bactericidal

Question 4

Do beta-lactams work in purulent debris?

Answer 4

NO!

Question 5

What are some mechanisms of resistance that bacteria form to beta-lactams?

Answer 5

1) Degraded by bacterial enzymes.
2) Alteration of binding site that penicillin interacts with.
3) Gram neg structure prevents penicillin binding (impaired crypticity)

Question 6

Are penicillins time-dependent or concentration dependent?

Answer 6

Time dependent.

Question 7

How are beta-lactams eliminated?

Answer 7

Renal elimination

Question 8

What do all beta-lactams work on?

Answer 8

Strep and anaerobes (these are the core for the beta-lactams).

Question 9

Penicillin G

Answer 9

“Narrow spectrum”.
Works on the core bacteria.
3 Forms: Crystalline [rapid] short duration, Procaine [slower] with prolonged duration, Benzathene [slowest] with longest duration.
Adverse rxns: Allergic, DO NOT GIVE TO HORSES/RABBITS (hind gut floral disruption).

Question 10

Ampicillin/Amoxicillin

Answer 10

“Broad spectrum”
Works on core bacteria + Pasteurella (in small animals) and Chlamydia.
Absorption: NOT absorbed well orally in horses.
Adverse rxns: Can cause diarrhea in horses. NEVER GIVE ORALLY TO RUMINANTS.

Question 11

Ticarcillin/Pipercillin

Answer 11

“Extended spectrum”
Works on core bacteria + E. coli, Pasteurella, and Pseudomonas.
Increased crypticity.

Question 12

Clavamox/Timentin

Answer 12

“Potentiated penicillins”
Beta-lactams + penicillinase inhibitor.
Works on core bacteria + Staph, Pasteurella, and B. fragilis. Only Timentin works on E. coli and Pseudomonas. Use Clavamox for Chlamydia in cats.