Incidence rate and outcome of gram-negative bloodstream infection in solid organ transplant recipients

Bacterial infections are common complications of solid organ transplantation (SOT). In this study, we defined the incidence, mortality and in vitro antimicrobial resistance rates of Gram-negative bloodstream infection (BSI) in SOT recipients. We identified 223 patients who developed Gram-negative BSI among a cohort of 3367 SOT recipients who were prospectively followed at the Mayo Clinic (Rochester, MN) from January 1, 1996 to December 31, 2007. The highest incidence rate (IR) of Gram-negative BSI was observed within the first month following SOT (210.3/1000 person-years [95% confidence interval (CI): 159.3-268.3]), with a sharp decline to 25.7 (95% CI: 20.1-32.1) and 8.2 (95% CI: 6.7-10.0) per 1000 person-years between 2 and 12 months and more than 12 months following SOT, respectively. Kidney recipients were more likely to develop Gram-negative BSI after 12 months following transplantation than were liver recipients (10.3 [95% CI: 7.9-13.1] vs. 5.2 [95% CI: 3.1-7.8] per 1000 person-years). The overall unadjusted 28-day all-cause mortality of Gram-negative BSI was 4.9% and was lower in kidney than in liver recipients (1.6% vs. 13.2%, p < 0.001). We observed a linear trend of increasing resistance among Escherichia coli isolates to fluoroquinolone antibiotics from 0% to 44% (p = 0.002) throughout the study period. This increase in antimicrobial resistance may influence the choice of empiric therapy.