End-to-End Timeliness of Blood Culture Diagnostics: A One-Month Observational Study of 5121 Bottles

Background/Objectives: To quantify end-to-end timeliness of the blood culture (BC) diagnostic workflow over one month using operational key performance indicators (KPIs)-transportation time (TT), time to detection (TTD), time to preliminary report (TTPR), and time to antimicrobial susceptibility testing (AST; TTAST)-and to identify actionable bottlenecks. Methods: This retrospective observational analysis included BC bottles processed between 29 September and 29 October 2023 at a large tertiary-care hospital in Italy. KPIs were computed from laboratory information system (LIS) timestamps and structured observations and were summarized as medians (interquartile range [IQR]). Results: 44.7% (2290/5121) of bottles reached the laboratory within 2 h (median 2.2 h, IQR 1.3-3.7), suggesting pre-analytical delays. Among adult bottles (n = 4995), 68.9% were underfilled (<8 mL), 12.9% met the 8-10 mL target, and 18.2% were overfilled (>10 mL). There were 932 positive bottles (18.2%), with a nocturnal peak in instrument flags despite reduced staffing. Median TTD was 12.6 h (IQR 8.9-18.4), with earlier detection for Gram-negatives than Gram-positives and yeasts (11.9, 14.5, and 30.9 h). In bacterial-positive bottles with complete timestamps (n = 294), median TTPR was 3.8 h (IQR 1.7-8.8); median TTAST was 19.2 h (IQR 14.3-27.8). From collection, median times were 17.9 h (IQR 14.2-23.1) to the preliminary report and 36.0 h (IQR 28.8-48.7) to the AST result. Conclusions: Within-laboratory steps were generally rapid, whereas transport planning and collection volumes emerged as major bottlenecks. Targeted interventions-enforcing ≤2 h TT and training to achieve an 8-10 mL fill-should further improve BC turnaround time.