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196. Increasing Bacteremia and Endovascular Infections due to Serratia marcescens: Implications for Evaluation and Treatment


 
 
 While Serratia marcescens can cause bloodstream infections (BSI), endocarditis or other endovascular infections are historically rare and typically due to injection drug use (IDU). Given the rise in IDU nationwide, and limited evidence for managing non-HACEK gram-negative endocarditis, we examined trends in the epidemiology of Serratia BSI and characterized management strategies.
 
 
 
 Our study was a retrospective analysis of adults admitted to UNC Health, a hospital network in North Carolina, from Apr 2014 to Mar 2021 with Serratia bacteremia. We used EMERSE, a program that searches free text in clinical notes, to identify those with ‘Serratia’ and either ‘bacteremia’ or ‘endocarditis’. This helped identify patients with microbiology obtained at outside hospitals. We performed chart review to confirm the Serratia BSI and collect demographic and clinical data. We tabulated yearly hospitalizations (Apr 1 to Mar 31), proportions of endovascular infections (endocarditis, cardiac device, vascular grafts), and described demographics and treatment approaches.
 
 
 
 We identified 97 patients by EMERSE and included 66 in analysis (Fig 1). 21 (32%) had endovascular infections and 21 (32%) overall were due to IDU (Table). Endovascular infections and BSIs increased over the period (Fig 2). Until 2018-2019, there were 0-10 Serratia BSIs yearly. In the final year, there were 37, 13 (37%) of which were endovascular infections. While we did not limit to S. marcescens, no other species were seen. 59/61 (97%) isolates with 3rd generation cephalosporin susceptibility reported were sensitive. 17/21 endovascular infections were endocarditis. 10/17 (59%) patients underwent valve replacement and 8/21 (38%) received dual antibiotic therapy for ≥ 6 weeks. Of the 10 attending infectious diseases follow-up visit, 6 were prescribed oral suppressive antibiotics after parenteral therapy.
 
 Figure 2. Serratia bloodstream infections (2014-2021)
 
 Table 1. Characteristics of Serratia bloodstream infections
 
 
 
 
 Serratia BSI and endovascular infections are markedly increasing, with a large component due to IDU. Given the high proportion of endocarditis, echocardiography may be considered for patients with Serratia BSI, particularly those with IDU or prosthetic material. Further studies are needed to confirm this phenomenon and to establish evidence for optimal management of Serratia endocarditis.
 
 
 
 Asher J. Schranz, MD, United HealthCare (Other Financial or Material Support, Spouse provides scientific review)
