Evaluation of blood culture contamination: impact on antibiotic use and clinical outcomes
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Publication Date
4-29-2026
Keywords
oregon, ppmc, ppmc gme, ppmc gme pharmacy
Disciplines
Medical Education
Abstract
Abstract: Blood cultures are one of the most frequently ordered microbiological tests in the hospital. While this diagnostic tool is necessary for determining management of certain infections, contaminated samples often lead to unnecessary antibiotic administration. Blood culture contamination is a critical aspect of antimicrobial stewardship, as previous literature has shown that treatment of a blood culture contaminant is associated with increased hospital costs, length-of-stay, morbidity, and mortality rates. To better understand the impact of blood culture contamination on patients within our facility, we evaluated antibiotic use and other patient outcomes associated with contaminated blood cultures. This was a single-center retrospective cohort study at a tertiary care hospital. Adult patients with two sets of blood cultures drawn within 24 hours of presentation to the hospital from March to August 2025 were screened for inclusion. Patients were excluded if only one set of blood cultures is drawn, if patient was not admitted to hospital, if true-positive blood culture not meeting microbiological contaminant definition, or neutropenic defined as absolute neutrophil count less than 500 cells/uL. The primary outcome was overall days of inpatient antibiotics in patients with contaminated blood cultures in comparison to patients with negative blood cultures. Secondary outcomes included in-hospital mortality, hospital length-of-stay, incidence of repeat blood cultures obtained, incidence of antibiotic escalation (addition of anti-MRSA therapy), and transthoracic echocardiograms performed. Patients were identified utilizing the electronic health record (EHR) and chart review was performed to record patient demographics (age, sex, BMI), patient characteristics (comorbidities, infection type), and evaluate the primary and secondary outcomes. Statistical analysis was performed utilizing student t-tests for continuous variables, chi-squared tests for categorical variables. A P-value of less than 0.05 was considered statistically significant. Results and conclusions will be shared when the project is completed. (IRB approved) Learning Objectives: Describe and evaluate clinical outcomes associated with contaminated blood culture results. Presentation Category: Antibiotic Stewardship
Specialty/Research Institute
Graduate Medical Education
Specialty/Research Institute
Pharmacy
