Impact and pattern of gram-negative bacteraemia during 6 y at a large university hospital

In order to characterize the impact and pattern of Gram-negative bacteraemia (GNB) at a Swiss University hospital and to assess the effect of multi-resistance on mortality, we conducted a 6-y retrospective cohort study using linear regression and multivariate Cox-proportional hazard analysis. 1766 patients had 1835 episodes of GNB; 61% were community-acquired. The incidence of GNB increased linearly (r2 = 0.90, p = 0.014) from 7.07 episodes to 8.32 episodes per 1000 admissions, but this trend was no longer significant after adjustment for the number of blood cultures drawn/y. The in-hospital mortality for patients with GNB decreased from 20% in 1989 to 16% in 1994 (r2 = 0.94, p = 0.005). The risk ratio for death remained unchanged over the study period and was 7-fold higher for patients with GNB than for patients without GNB. Factors independently associated with an increased hazard of death after GNB were: severity of illness as measured by exposure to intensive care (hazard ratio [HR], 1.5); age = 66-79 y (HR 1.8); GNB due to Klebsiella spp. (HR 1.7) or Pseudomonas aeruginosa (HR 1.6); and polymicrobial infection (HR 1.6). Multi-resistance was not associated with an increased risk of death (HR 1.0). Although the crude mortality of GNB decreased, the population-attributable risk ratio for death remained significant. These data suggest the absence of a major impact of multi-resistant GNB on patient mortality.