2243. Using Host Biomarkers and Time to Blood Culture Positivity to Predict Necessity for Echocardiogram in Patients with Staphylococcus aureus Endocarditis.

Background Patients with complicated S. aureus bacteremia (SaB) require a transesophageal echocardiogram (TEE) to rule out endocarditis. Risks of TEE may exceed benefits in patients with a low pretest probability of endocarditis. Given our prior findings that endovascular bacterial burden drives elevated serum IL-10 concentrations, we hypothesize that time to positive blood culture and IL-10 serum concentrations may be used to risk stratify patients for selection of TEE. We compared time to positive blood culture and serum IL-10 in patients with negative and positive TEE. Methods Patients with SaB were included if they had a diagnosis of primary, endovascular infection source of bacteremia identified by an infectious diseases consult team and a TEE performed. A retrospective chart review was done to identify the time to positivity (hours) of patient blood cultures grown aerobically or anaerobically and TEE results. Sera collected at clinical presentation of these patients were tested for biomarkers IL-10 and IL-1β. Mann–Whitney U test compared the data between the two groups. Results This study included 66 patients with SaB: 17 with negative TEE and 49 with positive TEE. Patients with a positive TEE confirming endocarditis had a faster time to positive blood cultures compared with patients with negative TEE (P = 0.031; figure). IL-10 serum concentrations were significantly higher in patients with positive TEE (26.2 pg/mL) vs. negative TEE (14.39 pg/mL). Time-to-positivity in blood culture was linearly associated serum IL-10 concentrations (P = 0.044; figure). Serum IL-1β concentrations were also higher in TEE positive vs. TEE negative patients (32.1 vs. 14.7 pg/mL, P = 0.067) Conclusion These data lend further evidence to link high endovascular bacterial burden (measured by shorter time to positive blood culture) and serum IL-10 concentrations. As anticipated, patients with positive TEE had significantly shorter time to blood culture positivity and higher IL-10 serum concentrations than those with negative TEE. With further study on a larger number of patients, time to positive blood cultures and serum biomarkers like IL-10 may be used to risk stratify patients for performance of TEE, as well as to select antimicrobial therapy and to adjust treatment duration. Disclosures All authors: No reported disclosures. [ABSTRACT FROM AUTHOR]