Recurrent gram-negative bloodstream infection (BSI) has not been evaluated in a population-based setting; therefore, we performed a population-based retrospective cohort study to examine the incidence, recurrence, and mortality rates of gram-negative BSI.

We identified 944 episodes of gram-negative BSI, including 98 recurrent episodes, among Olmsted County, Minnesota, residents from 1/1/1998 to 12/31/2007. Kaplan–Meier method was used to estimate the cumulative incidence rate of recurrence and 28-day all-cause mortality rate of gram-negative BSI. Cox proportional hazard regression was used to determine risk factors for recurrence.

The overall age- and gender-adjusted incidence rate of gram-negative BSI per 100,000 person-years was 84.5 (95% confidence interval [CI]: 79.1–90.0), including 75.7 (95% CI: 70.6–80.8) for first episodes and 8.8 (95% CI: 7.1–10.6) for recurrent episodes. Among 846 patients with first episodes of gram-negative BSI, the cumulative incidence rates of recurrence after 1, 5, and 10 years of the initial episode were 5.6%, 9.2%, and 14.6%, respectively, with death treated as a competing risk. Patients with Klebsiella species were more likely than those with Escherichia coli BSI to develop recurrent gram-negative BSI (hazard ratio: 2.33 [95% CI: 1.34–3.92], p=0.003). The 28-day all-cause mortality rates following the initial and second episodes of gram-negative BSI were 10.0% (95% CI: 8.0–12.0) and 11.3% (95% CI: 4.4–18.2), respectively.

Even though recurrent gram-negative BSI was relatively uncommon in the general population, up to 15% of patients with gram-negative BSI developed a recurrent episode within 10 years of the initial episode.