1992. Risk of Infective Endocarditis in Streptococcal mitis Bloodstream Infections Among Patients with Neutropenia from Hematologic Malignancies

Abstract

Abstract Background Streptococcus mitis is a common colonizer of the human oral and gastrointestinal tract. Patients with neutropenia due to hematologic malignancy (HM), particularly those prescribed fluoroquinolone prophylaxis are at increased risk of a S. mitis bloodstream infection (BSI). Risk of infective endocarditis (IE) in this patient population remains unclear. Methods This was a multicenter, retrospective study of neutropenic (ANC < 500 K/uL) patients with HM from November 2016 - February 2022. Patients were included if they had S. mitis isolated in at least 1 blood culture bottle. The primary outcome was number of patients who developed IE based on cardiac imaging. Secondary outcomes included number of patients who underwent IE workup via cardiac imaging and BSI recurrence within 12 weeks. Results Among 171 patients who met the inclusion criteria, 101 (59%) were male and median age was 60 years old (range 19-86). Patient demographics, microbiologic information and outcomes are shown in Table 1. All patients in the cohort had native cardiac valves. Acute leukemia/myelodysplastic syndrome was the most common HM (n=129, 75%), followed by lymphoma (n=27, 16%), multiple myeloma (n=10, 6%) and chronic leukemia (n=5, 3%). Most patients had a transthoracic echocardiogram (TTE) (n=97, 56.7%) within 7 days of BSI. Of these patients, 1 had suspected valvular vegetations on TTE, but transesophageal echocardiogram (TEE) was negative. Two patients had negative TTEs, but there was a high clinical suspicion, so cardiac computed tomography was performed and showed no valvular vegetations. Despite negative cardiac imaging, 1 patient completed 6 weeks of empiric treatment for IE based on radiographic findings in the torso suggesting visceral infarcts. One patient had S. mitis BSI recurrence within 12 weeks of first positive culture. Median duration of antimicrobial therapy for BSI was 15 days (range 8-43). Conclusion IE is uncommon in neutropenic HM patients with native cardiac valves and S. mitis BSI. In this cohort where approximately half had a TTE after bacteremia and median duration of BSI therapy was 15 days, recurrent BSI was rare, suggesting that IE cases were not underdiagnosed in those without cardiac imaging. Cardiac imaging such as TTE to rule out IE may not be necessary for all patients in this population. Disclosures Ramy H. Elshaboury, PharmD, Eli Lilly: Honoraria|Gilead Sciences: Grant/Research Support David W. Kubiak, PharmD, BCPS, BCIDP, FIDSA, Astellas Pharma, Inc.: Advisor/Consultant|AVIR Pharma Inc: Advisor/Consultant|Cidara Therapeutics: Advisor/Consultant Sarah P. Hammond, MD, F2G: Advisor/Consultant|F2G: Grant/Research Support|GSK: Grant/Research Support|Scynexis: Grant/Research Support.