Non-fermentative gram-negative bloodstream infection in northern Italy: a multicenter cohort study

Background The management of non-fermentative gram-negative bloodstream infection (NFGN-BSI) offers numerous challenges. In this study the aim is to analyse a large cohort of patients with NFGN-BSI recruited in the northern Italy to describe epidemiology, etiological and susceptibility pattern, therapeutic management and outcome. Methods Multicentre retrospective cohort study of patients hospitalised at three large teaching hospitals in northern Italy in a fourth year period. Results 355 BSI episodes were analyzed, due to P. aeruginosa (72.7%), A. baumannii (16.6%), and Stenotrophomonas maltophilia (10.7%). Overall, 21.4% of isolates were defined as DTR, highest rate among A. baumannii (64.4%). All-cause 30-day mortality rate was 17.5%. Rates of XDR or DTR A. baumannii isolation were significantly higher in non-surviving patients. Independent risk factors for 30-day mortality were: age (HR 1.03, 95%CI 1.00-1.04, p = 0.003), septic shock (HR 2.84, 95%CI 1.67-4.82, p < 0.001) and BSI due to Acinetobacter baumannii (HR 2.23, 95%CI 1.27-3.94, p = 0.005). Conclusion The overall prevalence of DTR was high in the NFGN BSI cohort analyzied, mainly among Acinetobacter baumannii episodes (64.4%). Acinetobacter baumannii is showed to be an independent predictor of mortality. These evidences marked the urgent need of new therapeutic options against this pathogen. Trial registration number: 79/2017/O/OssN. Approved: March14th, 2017.