Beta Lactam

Question 1

How did penicillin resistance happen?

Answer 1

There are 4 mechanism of resistance:
1) Inactivation of antibiotic by Beta-lactamase and related enzymes
2) Modification of target PBPs
3) Impaired penetration of drug to target PBPs
4) Efflux

Question 2

What are the subclasses of beta lactam?

Answer 2

1. Penicillin
2. Penicillin + Oxapenams
3. Cephalosporins
4. Carbapenems
5. Monobactams

Question 3

Side effects of beta lactam?

Answer 3

1. Allergic reaction
   Ø Hypersensitivities (0.4-7% of users) due to the products of penicillin degradation
   Ø Minor rash ( itching, mild urticaria or hives)
   Ø SJS
   Ø Toxic epidermal necrolysis (TEN)
   Ø Life threatening anaphylaxis ( laryngeal oedema, bronchoconstriction, hypotension)
   
   2. Bone marrow suppression (reversible): prolonged large dose
   3. Seizure (reversible): unadjusted doses in renal impaired
   4. Hepatotoxicity ( reversible):
      Ø Obstructive biliary toxicity reported with ceftriaxone
      Ø Hepatitis and cholestatic jaundice with Augmentin
   5. GI disturbance ( reversible)
      - Large PO doses

Question 4

When patient is on warfarin, and given ceftriazone, what effect might occur?

Answer 4

Cephalosporins + warfarin –> increase warfarin effects
- Due to reduce absorption of Vit K in the body
- Long-term use ( > 10 days), leading to Vit K deficiency
Leading to increase the anticoagulant effects of the blood thinning medication

Question 5

Ceftriaxone:

Answer 5

1. 3rd Gen cephalosporine
2. Good CNS Penetration, 90% protein binding
3. Not metabolized in liver
4. Eliminated in bilary route largely
5. Half life 8hrs
   6.time dependent killing
6. Do not reconstinute with any Ca diluents (such as Lactated ringer solution)

Question 6

Eg of monobactam

Answer 6

Ø Aztreonam
(IV/IM)

Question 7

E.g. of carbamenems

Answer 7

Ø Imipenem/Cilastatin””
Ø Meropenem
Ø Doripenem
Ø Ertanenem
IM/IV

“Imipenem: susceptible to degradation by DHP-1 enzyme in renal tubules; Cilastatin: is DHP-1 inhibitor

Question 8

When is on valproate for seizure, when giving meropenem, higher risk for seizure, due to

Answer 8

Ø Valproate + Meropenem–> decrease valproate level ( may apply to all carbapenems), AVOID CONCOMITANT USE