Cardiovascular System Infections: abx therapy

Question 1

Antibiotics for Endocarditis: initial ‘blind’ therapy

Answer 1

Amoxicillin IV
- 2 g every 4 hours
& consider

Gentamicin IV
- 3-5 mg/kg daily in 3 divided doses, every 8 hours

If allergic to penicillin:
Vancomycin IV
- 15-20 mg/kg every 8-12 hours 
& 
Gentamicin IV
- 3-5 mg/kg daily in 3 divided doses, every 8 hours

Question 2

Endocarditis (native valve) caused by staphylococci

Answer 2

Flucloxacillin IV

• 8 g daily in 4 divided doses (body weight <85kg)
• 12 g daily in 6 divided doses (body weight >85kg)

If penicillin allergic or MRSA:

Vancomycin IV
- 15-20 mg/kg every 8-12 hrs

&

Rifampicin IV or PO
- 0.6-1.2 g daily in 2-4 divided doses

Question 3

Endocarditis (prosthetic valve) caused by staphylococci

Answer 3

Flucloxacillin IV

• 8 g daily in 4 divided doses (body weight <85kg)
• 12 g daily in 6 divided doses (body weight >85kg)

&

Rifampicin IV or PO
- 0.6-1.2 g daily in 2-4 divided doses

&

Low-dose gentamicin IV
- 3-5 mg/kg daily in 3 divided doses, every 8 hours

If penicillin allergic or MRSA:

Vancomycin IV
- 15-20 mg/kg every 8-12 hrs

&

Rifampicin IV or PO
- 0.6-1.2 g daily in 2-4 divided doses

&

Low-dose gentamicin IV
- 3-5 mg/kg daily in 3 divided doses, every 8 hours

Question 4

Endocarditis caused by fully-sensitive streptococci

Answer 4

Benzylpenicillin sodium IV
- 1.2 g every 4 hrs, increased if necessary to 2.4 g every 4 hrs

If penicillin allergic:

Vancomycin IV
15-20 mg/kg every 8-12 hrs

&

Low-dose gentamicin IV
- 3-5 mg/kg daily in 3 divided doses, every 8 hours

Question 5

Endocarditis caused by less-sensitive streptococci

Answer 5

Benzylpenicillin sodium IV
- 1.2 g every 4 hrs, increased if necessary to 2.4 g every 4 hrs

&

Low-dose gentamicin IV
- 3-5 mg/kg daily in 3 divided doses, every 8 hours

If penicillin allergic:

Vancomycin IV
15-20 mg/kg every 8-12 hrs

&

Low-dose gentamicin IV
- 3-5 mg/kg daily in 3 divided doses, every 8 hours

Question 6

Endocarditis caused by enterococci

Answer 6

Amoxicillin IV
- 2 g every 4 hours 
&
Low-dose gentamicin IV
- 3-5 mg/kg daily in 3 divided doses, every 8 hours

If penicillin allergic or resistant:

Vancomycin IV
15-20 mg/kg every 8-12 hrs

&

Low-dose gentamicin IV
- 3-5 mg/kg daily in 3 divided doses, every 8 hours

Question 7

Endocarditis caused by Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, and Kingella species
(HACEK micro-organisms)

Answer 7

Amoxicillin IV
- 2g every 4 hrs

&

Low-dose Gentamicin

• IM or slow IV infusion
• 1 mg/kg every 12 hrs, administered over at least 3 minutes

If amoxicillin resistant:

Ceftriaxone

• IV or deep IM
• 2-4 g daily

&

Low dose Gentamicin

• IM or slow IV infusion
• 1 mg/kg every 12 hrs, administered over at least 3 minutes