2218. Evaluation of Bacteremia in Febrile Neutropenia and Implications on Antimicrobial Stewardship

BACKGROUND: Febrile neutropenia (FN) is a common complication in cancer patients. IDSA guidelines for FN in cancer patients recommend the initiation of an empiric antibiotic (abx) against Pseudomonas aeruginosa (PsA). At Olive View-UCLA Medical Center (Sylmar, CA), we reviewed FN cases to determine the prevalence of PsA bacteremia and assess the necessity of anti-PsA abx. METHODS: Retrospective chart review on all adult (≥ 18 years) positive blood cultures (Bcx) from January 1, 2017 to December 30, 2022. Positive Bcx were matched with ICD-10 code for neutropenia on inpatient encounter. Exclusion criteria consisted of absolute neutrophil count ≥ 500, FN not related to malignancy, and untreated suspected contamination. Charts were reviewed for Bcx results, source of bacteremia, antibiotic prescribing, and 30-day all-cause mortality. RESULTS: Of 1,303 neutropenia encounters and 3,755 positive Bcx, 92 were matched, and 48 met inclusion criteria. Enterobacterales was found in 28 (58.3%), whereas PsA was found in 5 (10.4%) [Figure 1]. Gram negative bacteremia was more common than gram positive [Figure 2]. The most common source of bacteremia was intra-abdominal (n=17, 35.4%), followed by line-associated infection (n=9, 18.8%) [Figure 3]. All 48 cases were started on empiric anti-PsA abx; 31 (72.1%) were continued on anti-PsA abx for an average of 11 days [IQR 5-14] despite no PsA in Bcx. 30-day all-cause mortality was not significantly different between those who continued on anti-PsA abx versus those in whom anti-PsA abx was stopped when PsA was not isolated [5/31 versus 3/13, p=0.5]. All cases of PsA bacteremia had at least one risk factor for nosocomial acquisition, e.g. hospitalization and/or abx exposure ≤ 90 days. [Figure: see text] [Figure: see text] [Figure: see text] CONCLUSION: The most common organism causing bacteremia in FN was Enterobacterales. The prevalence of PsA bacteremia was low, yet most were continued on anti-PsA abx despite Bcx showing a different organism. Continuation of anti-PsA abx did not make a difference in all-cause 30-day mortality when PsA was not isolated. Even when neutropenic, the risk factors for PsA bacteremia was the same as that for other patients; thus, as an abx de-escalation strategy, patients can be risk stratified. Further stewardship efforts can be focused on de-escalating anti-PsA abx in FN when PsA is not isolated. DISCLOSURES: All Authors: No reported disclosures