Introduction Staphylococcus aureus bacteraemia (SAB) is a common and severe infection, with a 90-day mortality of 24% - 32%. Cloxacillin is regarded as a first-line antibiotic treatment in SAB in Sweden.
However, exposure to cloxacillin in real-world hospitalised patients with SAB, most of whom are elderly patients treated outside the intensive care unit, is not well described. There are also limited data on the role of unbound cloxacillin exposure in relation to renal function or drug-induced toxicity.
Methods and analysis This multicentre, prospective, observational clinical trial will include 95 adult patients with methicillin-susceptible S. aureus bacteraemia, treated with cloxacillin.
Patients with endocarditis, polymicrobial bacteraemia or those considered unsuitable for cloxacillin treatment are excluded. Trough and peak total and unbound cloxacillin concentrations will be measured at steady state at days 2 and 7.
Blood cultures will be obtained at days 2, 3, 4 and 7 to assess time to negative culture. Renal function will be assessed daily for plasma creatinine and at days 1 and 6 for cystatin C and for 12-hour urine creatinine clearance.
BMJ Open published a clinical update in Research Highlights on 01 Apr 2026.
The item focuses on Unbound cloxacillin plasma concentrations in relation to toxicity and renal function: protocol for a prospective, observational clinical trial in a real-world Staphylococcus aureus bacteraemia population.
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