Optimal Treatment of MSSA Bacteraemias: a Meta-analysis of Cefazolin Versus Antistaphylococcal Penicillins

Background: Bacteraemias caused by MSSA are associated with significant morbidity and mortality. Controversy exists over the optimal treatment of severe infections caused by MSSA. This systematic review and meta-analysis aims to identify whether differences in clinical outcomes exist between cefazolin and antistaphylococcal penicillins (ASPs).

Methods: PubMed, Cochrane Library and Embase were systematically searched for publications reporting clinical outcomes of cefazolin and ASPs for adult patients with MSSA bacteraemias throughout November 2017. Comparative studies reporting 90 day mortality associated with each treatment were included. Random effects models were used to evaluate the impact of directed treatment agent on the odds of 30 and 90 day mortality, clinical failure, discontinuation due to adverse effects and infection recurrence.

Results: Five hundred and ninety-nine articles were evaluated for inclusion, of which seven met all inclusion criteria. Across all studies, 1589 patients received cefazolin and 2802 received an ASP. All-cause 90 day mortality was lower in patients who received cefazolin (OR 0.63, 95% CI 0.41-0.99; I2 = 58%). Odds of discontinuation due to adverse events was significantly lower in patients receiving cefazolin (OR 0.25, 95% CI 0.11-0.56; I2 = 13%). No differences in clinical failure were observed (OR 0.85, 95% CI 0.41-1.76; I2 = 74%).

Conclusions: This meta-analysis identified a significant decrease in mortality associated with cefazolin therapy for MSSA bacteraemia compared with ASPs, though no differences in clinical failure were observed. Additionally, cefazolin appeared to be better tolerated. These results should be interpreted with caution given the uncontrolled and retrospective nature of the included studies.