Carbapenems

Question 1

What class of antibiotics are carbapenems?

Answer 1

Beta-lactams (interfere with bacterial cell wall synthesis, leading to autolysis and cell death)

Question 2

What are the 3 carbapenem antibiotics?

Answer 2

1. Imipenem (always used with cilastatin)
2. Meropenem
3. Ertapenem

Question 3

What is the spectrum of activity of carbapenems?

Answer 3

Broad-spectrum (gram-positives, gram-negatives, and anaerobes)

Question 4

Which carbapenems have activity against P.aeruginosa? (2)

Answer 4

1. Imipenem (with cilastatin)
2. Meropenem

**Ertapenem is not active against P.aeruginosa

Question 5

Do carbapenems have activity against MRSA?

Answer 5

No

Question 6

Do carbapenems have activity against Enterococcus faecium?

Answer 6

No

Question 7

What 2 bacteria are all carbapenems inactive against?

Answer 7

MRSA and Enterococcus feacium

Question 8

What two bacteria is ertapenem inactive against (in addition to MRSA and E.faecium?)

Answer 8

Pseudomonas and Acinetobacter

Question 9

Why is cilastatin always administered with imipenem?

Answer 9

Imipenem is partially inactivated in the kidney; cilastatin is a specific enzyme inhibitor that blocks renal metabolism of imipenem

Question 10

What is the mode of delivery of carbapenems?

Answer 10

Injection; either IV infusion or IV injection

Question 11

What are the indications of imipenem (with cilastatin) and meropenem? (2)

Answer 11

1. Severe hospital-acquired infections
2. Polymicrobial infections including:
   - septicemia
   - hospital acquired pneumonia
   - intra-abdominal infections
   - skin and soft-tissue infections
   - complicated UTIs

Question 12

What are the indications for ertapenem? (4)

Answer 12

1. Abdominal infections
2. Gynecological infections
3. Community-acquired pneumonia (however, it is not active against atypicals and has limited activity against penicillin-resistant pneumococci)
4. Foot infectons (skin and soft tissue) in patients with DM

**remember, unlike the other carbapenems, ertapenem is not active against Pseudomonas or against Acinetobacter spp

Question 13

Do carbapenems have cross-reactivity with penicillins?

Answer 13

Yes, avoid if history of immediate hypersensitivity reaction to other beta-lactam antibacterials; use with caution in patients with sensitivity to beta-lactam antibacterials

Question 14

Can carbapenems be used in patients with epilepsy or a history of seizure?

Answer 14

Yes, however imipenem is know to lower the seizure threshold, so meropenem should be used preferentially for treatment of CNS infection

Question 15

What are some common side effects of carbapenems? (6)

Answer 15

Abdominal pain 
Diarrhea 
Skin rash 
Thrombocytopenia 
Headache 
Vomiting

Question 16

What is the major drug interaction for carbapenems?

Answer 16

Valproate

Carbapenems decrease the concentration of valproate