Single Daily versus Multiple-Daily Sputum Cultures for Guiding Antibiotic Therapy in ICU Patients with Pulmonary Infections: A Retrospective Cohort Study.

Background: Effective antibiotic management is crucial for ICU patients with pulmonary infections. However, guidelines are unclear whether the optimal strategy is multiple cultures on the infection onset day or a single daily culture to guide antibiotic therapy. Methods: This study involved 362 ICU patients with confirmed pulmonary infections, categorized into a "multiple-daily" group (≥2 cultures within 24 hours) and a "once-daily" group (1 culture per 24 hours). Propensity score matching was used to balance baseline characteristics. Primary outcome was antibiotic adjustment rate. Secondary outcomes included mechanical ventilation duration, ICU and total hospital length of stay, hospitalization costs, and mortality. Results: The multiple-daily group had more frequent antibiotic adjustments both before and after matching (76.88% vs 67.33%, Conclusion: In ICU patients with pulmonary infections, multiple-daily sputum cultures lead to more frequent antibiotic adjustments and better detection of multidrug-resistant pathogens. However, a once-daily culture strategy is associated with reduced healthcare resource utilization and comparable mortality. Further randomized trials are needed to determine the optimal sputum culture frequency in the ICU setting. Trial Registration: This study was registered with the Chinese Clinical Trial Registry under the registration number ChiCTR2400091085.