Comparison between two blood collection techniques for the diagnosis of bacteremia in patients with sepsis: unique blood culture vs. the standard method of multiple blood cultures

Introduction: In clinical practice, bloodstream infections, which often occur alongside sepsis, remain among the most serious and life-threatening conditions, with mortality rates as high as 50%. This study aimed to compare the diagnostic performance of a single venipuncture blood culture strategy (30 mL) with the standard method of multiple blood cultures in patients with sepsis. Materials and methods: A prospective paired within-patient diagnostic comparison study was conducted at the Fundación Cardioinfantil (Bogotá, Colombia) between April 2019 and May 2020. Adult patients with sepsis (SOFA >2) for whom blood cultures were ordered by the treating physician were included in the study. Each patient underwent three venipunctures according to the institutional protocol (10 mL each), and an additional 30 mL sample was collected through a single venipuncture for blood culture. A total of 113 patients were included in the analysis. Results: The single blood culture technique showed a relative sensitivity of 97.6% (95% CI: 87.1–99.9) and relative specificity of 95.8% (95% CI: 88.3–99.1), with high agreement between both strategies (AUC 0.967; 95% CI: 0.934–1). Compared to the standard technique, the single blood culture demonstrated a comparable diagnostic yield while reducing collection time and patient discomfort. Discussion: The single blood culture technique (30 mL) may represent a feasible and less invasive alternative, showing comparable diagnostic yield and agreement with the standard method. These findings should be interpreted as a comparison between sampling strategies, given the absence of a truly independent gold standard. Multicenter studies with larger blood volumes are needed to confirm these findings, and their impact on clinical outcomes should be evaluated before supporting their incorporation into clinical practice guidelines.