Incidence and predictors of complications in Gram-negative bloodstream infection

Background The incidence of metastatic complications in Gram-negative bloodstream infection (GN-BSI) remains undefined. This retrospective cohort study examines the incidence and predictors of complications within 90 days of GN-BSI. Methods Patients with GN-BSIs hospitalized at two Prisma Health-Midlands hospitals in Columbia, South Carolina, USA from 1 January 2012 through 30 June 2015 were included. Complications of GN-BSI included endocarditis, septic arthritis, osteomyelitis, spinal infections, deep-seated abscesses, and recurrent GN-BSI. Kaplan–Meier analysis and multivariate Cox proportional hazards regression were used to examine incidence and risk factors of complications, respectively. Results Among 752 patients with GN-BSI, median age was 66 years and 380 (50.5%) were women. The urinary tract was the most common source of GN-BSI (378; 50.3%) and Escherichia coli was the most common bacteria (375; 49.9%). Overall, 13.9% of patients developed complications within 90 days of GN-BSI. The median time to identification of these complications was 5.2 days from initial GN-BSI. Independent risk factors for complications were presence of indwelling prosthetic material (hazards ratio [HR] 1.73, 95% confidence intervals [CI] 1.08–2.78), injection drug use (HR 6.84, 95% CI 1.63–28.74), non-urinary source (HR 1.98, 95% CI 1.18–3.23), BSI due to S. marcescens, P. mirabilis or P. aeruginosa (HR 1.78, 95% CI 1.05–3.03), early clinical failure criteria (HR 1.19 per point, 95% CI 1.03–1.36), and persistent GN-BSI (HR 2.97, 95% CI 1.26–6.99). Conclusions Complications of GN-BSI are relatively common and may be predicted based on initial clinical response to antimicrobial therapy, follow-up blood culture results, and other host and microbiological factors.