Gram-negative bloodstream infections.

Over the last 22 years we have prospectively recorded data for bloodstream infections (BSIs) in our institution. We reflect the experience of a tertiary teaching hospital with 1750-2500 beds that served a population ranging during the study period from 650,000 to 750,000 inhabitants. Definitions and microbiological methods were standard. The microbiological workload of blood cultures was analysed and the evolution of the incidence of BSI episodes, provided as episodes per 1000 admissions and per 100000 inhabitants, is reported. During the study period, our institution had over one million admissions; blood culturing increased from 299 blood cultures/1000 admissions in the year 1985 to 720/1000 admissions in 2006. Overall, there were 65475 blood cultures with recovery of significant microorganisms, representing 27 419 episodes of significant BSI (22626 patients). The present paper describes the Gram-negative organisms recovered from the blood cultures and discusses their clinical significance.