TOPLINE

Patients with Staphylococcus aureus bacteremia treated with flucloxacillin were more likely to develop acute kidney injury (AKI) compared with those treated with cefazolin, with most AKI cases developing within the first week after blood culture collection. Among patients who developed AKI, recovery rates declined progressively with increasing severity, from more than 80% in stage 1 to approximately 50% in stage 3.

METHODOLOGY

• A retrospective cohort study analyzed 1408 adults (median age, 67 years; 62.6% men) with S aureus bacteremia treated with first-line cefazolin or flucloxacillin at three hospitals in the Netherlands.
• Participants included 1324 patients treated with flucloxacillin and 84 treated with cefazolin; the median duration of antibiotic treatment was 13 days.
• AKI was staged according to Kidney Disease: Improving Global Outcomes criteria, based on serum creatinine measurements obtained after the first S aureus-positive blood culture during hospitalization.
• Researchers assessed AKI incidence, severity, timing of onset, and renal recovery; multivariable logistic regression was used to evaluate associations between antibiotic treatment and AKI occurrence.
• Among flucloxacillin-treated patients, researchers examined whether initial daily dose (6-8 g/d vs 12 g/d) was associated with AKI risk.

TAKEAWAY

• AKI occurred in 35.2% of flucloxacillin-treated patients compared with 20.2% of cefazolin-treated patients (P = .004), with flucloxacillin use independently associated with higher AKI risk after multivariable adjustment (adjusted odds ratio [aOR], 2.37; 95% CI, 1.30-4.55). Flucloxacillin use also showed higher odds for early AKI (≤ 7 days) compared with cefazolin (aOR, 2.51; P = .007), but no significant association with late-onset AKI (> 7 days; P = .23).
• Among patients who developed AKI, the median time from the first S aureus-positive blood culture to AKI onset was 1.3 days in both treatment groups, with 80.3% of AKI cases occurring within 7 days of the index blood culture.
• Recovery within 30 days declined with increasing AKI severity, from 81.7% in stage 1 to 64.5% in stage 2 and 50.5% in stage 3.
• Among flucloxacillin-treated patients, high-dose regimens (12 g/d) were not associated with increased AKI risk compared with lower doses (6-8 g/d), with similar AKI incidence, severity distribution, and timing between dosing groups.

IN PRACTICE

"Flucloxacillin remained independently associated with a substantially higher risk of AKI than cefazolin... Across commonly used dosing regimens, we did not observe meaningful differences in AKI occurrence, timing or severity," the authors wrote.

SOURCE

The study was led by F.S. Sinkeler, Department of Pharmacy, Pharmacology and Toxicology, Radboud University Medical Center in Nijmegen, the Netherlands. It was published online on September 2 in Journal of Antimicrobial Chemotherapy.

LIMITATIONS

Cefazolin-treated patients constituted a smaller proportion of the cohort, limiting precision for subgroup analyses. Confounding by indication cannot be fully excluded despite adjustment for disease severity markers.

DISCLOSURES

This study was supported by ZonMw. The authors reported no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.