In this episode, I’ll discuss the evidence supporting using cefazolin for MSSA bacteremia.
The strongest data on what to use to treat MSSA bacteremia has always been for the penicillinase-resistant penicillins like nafcillin and cloxacillin. But these antibiotics have high rates of adverse events. Cefazolin has a much more favorable safety profile and is preferred by many clinicians for this reason; however, data suggesting it is equivalent to the penicillinase-resistant penicillins for MSSA bacteremia is retrospective in nature.
For this reason, a group of researchers published in the Lancet the results of their prospective, open-label, multicentre, non-inferiority, randomized clinical trial looking at Cloxacillin versus cefazolin for meticillin-susceptible Staphylococcus aureus bacteremia.
Researchers enrolled 315 patients with MSSA bacteremia. Patients with endocarditis were not excluded, but no one with an intravascular implant or suspected CNS infection was allowed in the study. Patients were then randomly assigned (1:1) to receive intravenously cefazolin (25–50 mg/kg every 8 hours) or cloxacillin (25–50 mg/kg every 4–6 hours) for the first 7 days of therapy. Therapy was continued for at least 14 days, but after day 7, clinicians could change the antibiotic if they wished. The primary endpoint was a composite of sterile blood cultures at day 3 (day 5 for endocarditis) without relapse of bacteremia, survival, and clinical success at day 90.
The primary endpoint was experienced by 75% of the patients in the cefazolin group versus 74% in the cloxacillin group, and this met criteria for non-inferiority.
Mirroring real-world experience, the rate of serious adverse events was significantly higher in the cloxacillin group at 27% vs just 15% in the cefazolin group. When the analysis was limited to just those patients who experienced the adverse event of acute kidney injury, this occured in 12% of the cloxacillin patients but just in 1% of the cefazolin patients.
The authors concluded:
Cefazolin constitutes an alternative to cloxacillin for the treatment of MSSA bacteraemia, offering non-inferior clinical efficacy and potentially enhanced tolerability.
This provides important information to give clinicians confidence that when they choose cefazolin for MSSA bacteremia in select patients, the favorable adverse event profile does not seem to come at the expense of clinical effectiveness.
The article in this episode is a selection from my Hospital Pharmacy Academy’s weekly literature digest. Have you ever felt like your physician colleagues are one step ahead of you with new literature developments? Every week, Academy members are provided a summary curated and explained by me of the top hospital pharmacy-related articles published that week from over 20 major journals and sources to save you time and keep you up to date with the literature. To get immediate access, go to pharmacyjoe.com/academy.
If you like this post, check out my book – A Pharmacist’s Guide to Inpatient Medical Emergencies: How to respond to code blue, rapid response calls, and other medical emergencies.
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