Abstract
BACKGROUND: Infective endocarditis due to Serratia spp. (S-IE) has historically been considered a rare entity. Typically linked to injection drug use (IDU), S-IE appears to be a growing problem as the harms of unsafe drug use proliferate. However, guidance on therapy for Gram-negative IE remains limited. METHODS: This was a retrospective analysis of adults treated for S-IE at 4 academic health systems in different US states from 2015 to 2021. Multivariable logistic regression analyzed the association of inpatient mortality with procedural management and combination antibiotic treatment. RESULTS: A total of 159 cases of S-IE were identified with a qualitative overall increase across the period, and a peak in 2019, although trends varied by site. Seventy-five were due to IDU, 57% involved a single left-sided valve, and inpatient mortality was 21%. In adjusted analyses, including 117 cases from 3 sites, lower inpatient mortality was associated with procedural intervention (odds ratio 0.14; 95% confidence interval, .03-.64) and combination antibiotic therapy (odds ratio 0.15; 95% confidence interval, .03-.74). DISCUSSION: In this multicenter study, we found that S-IE may be increasing, is commonly associated with IDU, is treated with varying strategies and carries high inpatient mortality. Procedural intervention and combination antibiotics were associated with lower mortality. Our study is limited by varying methods of case identification and a lack of data on clinical severity and surgical indications. Further study is urgently needed to define best management practices.