Prevalence of acute kidney injury in Staphylococcus aureus bacteraemia treated with cloxacillin: a retrospective cohort study.

BACKGROUND

Preliminary results from the SNAP trial presented at ESCMID Global 2025 reported a high incidence (19.8%) of acute kidney injury (AKI) in patients treated with (flu)cloxacillin for Staphylococcus aureus bacteraemia (SAB).

OBJECTIVE

In Sweden, cloxacillin is used at lower daily doses, and the risk of nephrotoxicity has not been assessed in this setting.

METHODS

We retrospectively evaluated renal outcomes in SAB patients with cloxacillin treatment. Patients on chronic dialysis or lacking creatinine measurements during treatment were excluded. AKI was defined as per the SNAP criteria. Long-term renal function was evaluated using follow-up creatinine values up to 12 months post-treatment.

RESULTS

Of 275 included patients, 13.8% had pre-existing renal impairment. Cloxacillin doses in median were 8 g/24h (IQR 6-8). AKI occurred in 35 patients (12.8%), of which 26 had AKI stage 1, four had AKI stage 2 and five had AKI stage 3. AKI was associated with higher Pitt Bacteraemia Score, pre-existing renal disease and high-dose cloxacillin. Among survivors (n = 239), only four patients (1.3%) had verified persistent renal impairment at follow-up.

CONCLUSION

Compared to results from the SNAP trial, cloxacillin was associated with a lower incidence of AKI that was mostly mild and transient. Persistent renal impairment was rare. The data suggest that cloxacillin at lower dosing levels is less nephrotoxic and potentially safe to use.