Methicillin- and penicillin-susceptible S. aureus bacteraemia
Australian Commission on Safety and Quality in Health Care (ACSQHC), 2023
When used to treat methicillin-susceptible S. aureus (MSSA) bacteraemia, including penicillin-susceptible S. aureus (PSSA) bacteraemia, beta lactams are associated with improved outcomes (eg reduced mortality) when compared with other antimicrobials, including vancomycin.
For directed therapy for methicillin-susceptible S. aureus bacteraemia in adults and children 1 month and older, useDavis, 2018Lecomte, 2021Legg, 2023Rindone, 2018Weis, 2019:
1cefazolin 2 g (child: 50 mg/kg up to 2 g) intravenously, 8-hourly. For patients with septic shock or requiring intensive care support, use a 6-hourly dosing interval. For dosage adjustment in adults with kidney impairment, see cefazolin dosage adjustment. See advice on duration of therapy cefazolin cefazolin cefazolin
OR
1flucloxacillin 2 g (child: 50 mg/kg up to 2 g) intravenously, 6-hourly. For patients with endocarditis or septic shock, or those requiring intensive care support, use a 4-hourly dosing interval. For dosage adjustment in adults with kidney impairment, see flucloxacillin intravenous dosage adjustment. See advice on duration of therapy. flucloxacillin flucloxacillin flucloxacillin
For directed therapy for methicillin-susceptible S. aureus bacteraemia in neonates, use:
1cefazolin intravenously. See advice on duration of therapy cefazolin
postnatal age less than 8 days and weighing less than 2 kg: 25 mg/kg 12-hourly
postnatal age less than 8 days and weighing 2 kg or more: 50 mg/kg 12-hourly
postnatal age 8 days or older and weighing less than 2 kg: 25 mg/kg 8-hourly
postnatal age 8 days or older and weighing 2 kg or more: 50 mg/kg 8-hourly
OR
1flucloxacillin 25 mg/kg intravenously, 4-hourly. See advice on duration of therapy. flucloxacillin
Accumulating evidence suggests that cefazolin is as effective as flucloxacillin for the treatment of methicillin-susceptible S. aureus bacteraemia and may have lower risk of acute kidney injury. However, there are no published randomised controlled trials comparing cefazolin with flucloxacillin for this indication.
Some MSSA isolates are susceptible to penicillin (eg benzylpenicillin); however, confirmation of penicillin-susceptible S. aureus (PSSA) can be challenging. For confirmed penicillin-susceptible S. aureus bacteraemia, in adults and children 1 month or older, use:
benzylpenicillin 2.4 g (child: 60 mg/kg up to 2.4 g) intravenously, 6-hourly. For dosage adjustment in adults with kidney impairment, see benzylpenicillin dosage adjustment. See advice on duration of therapy. benzylpenicillin benzylpenicillin benzylpenicillin
For confirmed penicillin-susceptible S. aureus bacteraemia in term neonates (gestational age 37 weeks or older), use:
benzylpenicillin 60 mg/kg intravenously; see advice on duration of therapy benzylpenicillin
postnatal age 0 to 7 days: 12-hourly
postnatal age 8 days or older: 8-hourly.
For patients with MSSA or PSSA bacteraemia who have had a nonsevere (immediate or delayed) or a severe immediate1 hypersensitivity reaction to a penicillin, use cefazolin (as above).
For patients with MSSA or PSSA bacteraemia who have had a severe delayed2 hypersensitivity reaction to a penicillin, use vancomycin (as for methicillin-resistant S. aureus bacteraemia).