Clinical Scorecard: Cefazolin Compared With Cloxacillin for MSSA Bacteremia: Meta-Analysis of Two Randomized Trials
At a Glance
Category
Detail
Condition
Clinical topic addressed by the source article: Cefazolin Compared With Cloxacillin for MSSA Bacteremia
Key Mechanisms
The analysis compared cefazolin with cloxacillin or flucloxacillin for mortality, treatment discontinuation due to adverse events, and acute kidney injury. The authors discuss the theoretical cefazolin inoculum effect; its relevance remains uncertain.
Target Population
Population described in the source article.
Care Setting
The source reports enrollment across 112 hospitals in 9 countries but does not specify a particular care setting.
Key Highlights
Across 1,579 evaluable patients, cefazolin had a 95.5% posterior probability of noninferiority for 90-day mortality using an OR threshold of 1.2, corresponding to the prespecified 2.5% absolute risk-difference margin.
The estimated mortality OR was 0.84 (95% CrI, 0.59-1.28); the probability of superiority was 81.0%.
Cefazolin had a 99.9% probability of superiority for fewer treatment discontinuations due to adverse events (OR, 0.25; 95% CrI, 0.13-0.48).
Cefazolin had a 98.4% probability of superiority for lower acute kidney injury incidence (OR, 0.54; 95% CrI, 0.25-0.97).
The authors report that only two randomized trials were available, with SNAP contributing 82% of the data; subgroup findings were limited by small numbers.
Guideline-Based Recommendations
Diagnosis
Management
The authors state that the findings support preferring cefazolin for adults with MSSA bacteremia; this is the authors’ conclusion, not a guideline recommendation.
Monitoring & Follow-up
Risks
Both trials were open-label and each was judged to have some concern of bias; overall risk of bias was judged low for both trials.
Acute kidney injury definitions differed slightly between trials, and CloCeBa estimates were not covariate adjusted.
The trials included too few patients with endocarditis or S. aureus type A blaZ gene to support meaningful subgroup inferences.
Patient & Prescribing Data
The mortality analysis included 791 patients assigned to cefazolin and 788 assigned to cloxacillin or flucloxacillin.
In the pooled analysis, cefazolin had lower odds of treatment discontinuation due to adverse events and acute kidney injury than antistaphylococcal penicillins. The authors also cite cefazolin’s longer half-life, tolerability, and potential use in patients with penicillin allergy as advantages.
Clinical Best Practices
Interpret the mortality result as a 95.5% posterior probability of noninferiority at the prespecified OR threshold of 1.2, corresponding to a 2.5% absolute risk-difference margin; the estimated probability of superiority was 81.0%.
The authors note limitations from the two-trial evidence base, differences in outcome definitions, and lack of covariate adjustment for CloCeBa estimates.
The authors state that the endocarditis and type A blaZ subgroup results do not support meaningful inferences because of small sample sizes.
by Todd C. Lee, Steven Y. C. Tong, Joshua S. Davis, Arthur M. Albuquerque, Matthew P. Cheng, Jacob Dye, Nesrin Ghanem-Zoubi, Anna L. Goodman, Nynke G. L. Jager, Achim J. Kaasch, Ilse J. E. Kouijzer, David C. Lye, Alistair R. D. McLean, Brendan J. McMullan, David L. Paterson, Connor Prosty, Jason A. Roberts, Pierre Tattevin, Jonas Tverring, Dafna Yahav, Emily G. McDonald
