Uncomplicated Staphylococcus aureus bacteraemia: Partial oral treatment is comparable to fully intravenous treatment – A single centre retrospective cohort study

Background: Staphylococcus aureus bacteraemia (SAB) is a serious infection associated with high mortality. Current treatment often consists of 14 days of intravenous antibiotics. Significant variability in practice is seen, with some advocating an intravenous to oral antibiotic switch can be considered in uncomplicated SAB. We aimed to describe current antimicrobial strategies used to manage uncomplicated SAB in our UK based hospital. We also assessed outcomes of patients with uncomplicated SAB in those treated with a intravenous to oral antibiotic switch within 14 days.

Methods: This was a single-centre, retrospective, cohort study between 2018 and 2020 of patients with SAB. Patients with complicated SAB were excluded. Outcomes measured were 90-day relapse, 30-day mortality and length of stay.

Results: We identified 237 patients with SAB, 103 of whom had uncomplicated bacteraemia and were included in the analysis. Of these, 38 (37 %) had an intravenous to oral antibiotic switch within 14 days. Oral antibiotics used included flucloxacillin (n = 32, 84 %), linezolid (n = 4, 11 %), co-trimoxazole (n = 1, 3 %), and doxycycline (n = 1, 3 %). 30-day mortality was lower in patients who received an intravenous to oral switch within 14 days compared to those who did not (16 % vs 37 % p = 0.026). In order to exclude patients who died early or had inadequate courses of antibiotics, we removed those who received less than 7 days antibiotics. On re-analysis there was no statistical difference in outcomes except for median length of stay (14 days vs 32 days p < 0.0001), which was shorter for the group receiving an oral switch.

Conclusions: There is clinical equipoise in whether patients in our centre receive an intravenous to oral switch for uncomplicated SAB. Treatment of uncomplicated SAB with an intravenous to oral switch within 14 days, demonstrated similar clinical outcomes to standard intravenous therapy with reduced length of stay.