Impact of a single-set blood culture restriction during the 2024 national blood culture bottle shortage on patient outcomes: an interrupted time series analysis.

OBJECTIVE

To evaluate the clinical and stewardship consequences of a single-set blood culture restriction implemented during the 2024 national blood culture bottle shortage.

DESIGN

Interrupted time series analysis of hospitalizations from June 26, 2023, to June 25, 2025.

SETTING

Two tertiary hospitals in an urban academic health system.

PATIENTS: 116,341 inpatient hospitalizations, including 31,034 with ≥1 blood culture obtained.

INTERVENTION: A systemwide electronic health record order restriction from June 26 to December 23, 2024, limiting clinicians to one blood culture set per patient every 24 hours.

RESULTS

In-hospital mortality or hospice discharge declined before restriction (-1.3%/week; P < .001), flattened during restriction (+0.8%/week; P = .20), and declined again after restriction (-2.8%/week; P < .001). Overall blood culture positivity increased from 9.6% prerestriction to 11.2% during restriction and decreased to 10.2% postrestriction. Upon restriction onset, hospitalizations with ≥1 blood culture decreased 29.7% (P < .001). Among hospitalizations with ≥1 blood culture, mean cultures per hospitalization decreased 52.6% (P < .001), time to first culture increased 39.5% (P < .001), and time to first antimicrobial increased 13.8% (P = .04). Days of antimicrobial therapy increased among hospitalizations with and without blood cultures by 12.6% (P = .001) and 10.6% (P < .001), respectively.

CONCLUSIONS

A near-universal single-set blood culture restriction was associated with decreased and delayed diagnostic testing, delayed antimicrobial initiation, increased antimicrobial exposure, and temporal changes in clinical outcomes. Crisis-driven diagnostic stewardship interventions should include indication-specific guidance and real-time safety monitoring.