2249. Impact of Minimum Inhibitory Concentration on Clinical Outcomes of Daptomycin for VRE Bloodstream Infection Among Neutropenic Oncology Patients

Abstract

BackgroundVancomycin-resistant Enterococcus (VRE) bloodstream infection (BSI) is a significant cause of morbidity and mortality in immunocompromised patients. This study aimed to assess the impact of daptomycin (DAP) MIC on outcomes of treatment for VRE BSI in neutropenic oncology patients.MethodsThis was a retrospective, observational, single-center, cohort study at an academic medical center. Included: age ≥ 18, neutropenia, admitted to oncology unit, and DAP for VRE BSI. Excluded: death within 24 hours after initiation of DAP, polymicrobial BSI, and linezolid use for > 48 hours before DAP initiation. Patients with VRE BSI 2008–2018 were identified using a report from the micro lab. Data were collected by electronic medical record review. The primary outcome of the study was clinical success, defined as culture sterilization, hypotension resolution, defervescence, and no need to change DAP due to persistent signs/symptoms of infection. Patients were analyzed according to DAP MIC ≤ 2 vs. ≥ 4 mg/L. Multivariable logistic regression analysis was performed to identify factors associated with clinical success.Results44 patients met study criteria (MIC ≤ 2, n = 26; MIC ≥ 4, n = 18). Mean age was 58 years, 59% were male, and median ANC was 0. Median Charlson Comorbidity Index Score and Pitt Bacteremia Score (Pitt) were 5 and 1, respectively. 34% required ICU admission. More patients achieved clinical success with MIC ≤ 2 (88% vs. 56%; P = 0.03). Time to success (2.4 vs. 4 days, P = 0.02) and time to culture sterilization (2.2 vs. 2.9 days, P = 0.24) were shorter with MIC ≤ 2. Mortality was similar between groups (31% vs. 33%). Time to culture sterilization (P = 0.008), neutropenia resolution (P = 0.02), MIC group (P = 0.096), and Pitt (P = 0.52) were included in the multivariable model.ConclusionDAP MIC should be considered when choosing therapy for VRE BSI among neutropenic oncology patients, particularly those expected to have prolonged neutropenia and those with persistently positive cultures. Disclosures All authors: No reported disclosures.