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.