Fig. 1

Flow chart of study and flow diagram of classification algorithms for deep surgical site infection. (SSI: surgical site infection; ECDC: European Centre for Disease Prevention and Control. Admissions: Length of stay ≥ 14 days or 1 readmission to original department or in-hospital mortality within follow-up (FU) time (= 45 days after surgery). Reoperations: Any reoperation by original surgery specialty within FU time. Radiology: ≥1 orders for CT scan within FU time. Antibiotics: ≥3 consecutive days of antibiotics (ATC J01) within FU time, starting after day 1. Microbiology: ≥1 culture taken from relevant body sites within FU time, excluding cultures taken on any day prior to day 1. Original classification algorithm: Figure originally published in van Rooden et al. [8], adapted and used with permission. Adapted classification algorithm: Figure originally published in Verberk et al. [9], adapted and used with permission)