Gram-negative septic thrombosis in critically ill patients: A retrospective case–control study

Background: Data on septic thrombosis caused by Gram-negative bacilli (GN-ST) in intensive care unit (ICU) patients are currently limited. Methods: The aim of this retrospective case–control study (matched 1:3) performed over a 15-month period on ICU patients with bacteraemia, associated (cases) or not (controls) with GN-ST, was to assess 30-day mortality and clinical/microbiological features of GN-ST. Results: During the study period, 16 patients with GN-ST and 48 controls were analyzed. Polytrauma was the cause of ICU admission in 12 (75%) cases and 22 (46%) controls (p = 0.019). In no case of septic thrombosis was surgical debridement performed. The site of venous thrombosis was more frequently in the lower limbs, associated with bone fracture in nine out of 12 (75%) cases. The median duration of bacteraemia (22 days vs 1 day; p < 0.001) and time to clinical improvement (15 days vs 4 days; p < 0.001) were significantly longer in cases than in controls. On analysis of the receiver operating characteristics (ROC) curve, bacteraemia >72 h was significantly associated with GN-ST (area under the curve (AUC) 0.95, sensitivity 0.996 and specificity 0.810; p < 0.001). Finally, 30-day mortality was 20% in cases and 67% in controls (p < 0.001). Conclusions: Critically ill patients with GN-ST showed specific clinical features. Despite delayed bacteraemia clearance, targeted antibiotic therapy plus anticoagulation usually provided clinical improvement and a low 30-day mortality rate.