2026 Eastern States Conference

Title: Assessing clinical impact of coagulase-negative staphylococci blood cultures determined to be contaminants 
 
Authors: Morgan Mendes, PharmD; Michael Miller, PharmD, BCPS, BCIDP 
 
Objective: Identify appropriate antimicrobial stewardship strategies when coagulase-negative staphylococci blood cultures are determined to be contaminants. 
 
Self-Assessment Question: Which antimicrobial stewardship strategy is most appropriate when a positive blood culture is determined to be a contaminant in a clinically stable patient with no signs of infection? 
A. Continue vancomycin until repeat cultures are negative 
B. De-escalate or discontinue vancomycin after culture review 
C. Add gram-negative coverage 
D. Switch to daptomycin 
 
Background: Blood cultures are a tool for diagnosing sepsis, yet 1-2% represent contamination. Treating contaminants as true infections can lead to unnecessary antibiotic use and increased healthcare costs. 
 
Methods: This retrospective cohort study evaluated adults admitted to TidalHealth Peninsula Regional between October 1, 2023, and October 1, 2025, with a single positive blood culture for coagulase-negative staphylococci from the emergency department. Patients with risk factors for true bacteremia were excluded. The primary objective was to compare hospital length of stay between patients who continued vancomycin and those who did not receive or were de-escalated from vancomycin within 24 hours of contaminant culture identification. Length of stay was analyzed using a Mann–Whitney U test. Secondary outcomes included incidence of acute kidney injury and new infectious disease consults, analyzed using a Fisher’s exact or chi-square test as appropriate. 
 
Results: Of 449 patients reviewed, 281 met inclusion criteria. Median hospital length of stay was significantly shorter in the de-escalation group compared to the continued vancomycin group (2-day difference, 95% CI 1–3; p < 0.001). No patients in the de-escalation group experienced acute kidney injury compared to three patients in the continued group (0% vs 3.5%; p = 0.30). New infectious disease consults within 72 hours occurred more frequently in patients who continued vancomycin (34%) compared to those de-escalated (24.6%, p < 0.001). 
 
Conclusion: Early avoidance or de-escalation of vancomycin in patients with blood culture contaminants may reduce unnecessary antibiotic exposure and hospital length of stay. These findings support antimicrobial stewardship strategies focused on early culture review and targeted de-escalation.