Epidemiological and clinical characteristics of bacteraemia caused by Aeromonas spp. as compared with Escherichia coli and Pseudomonas aeruginosa.

We reviewed 75 episodes of Aeromonas spp. bacteraemia observed at our institution in 1979-2002, with special reference to episodes occurring in elderly patients (> or = 65 y) and to nosocomial episodes. In addition, we compared monomicrobial bacteraemic episodes caused by Aeromonas spp. (n = 54) with those caused by Escherichia coli (n = 108) and Pseudomonas aeruginosa (n = 108), to assess differences in clinical presentation and outcome. The 75 episodes of Aeromonas spp. bacteraemia occurred mainly in males (72%), suffering from chronic liver disease (36%) or neoplasm (33%). They had an abdominal origin in 52% of cases, were recorded as primary bacteraemia in 40%, and showed a 30-d case fatality rate of 36%. 22 episodes (29%) were nosocomial, 36 (48%) occurred in elderly patients and 21 (28%) were polymicrobial infections. In comparison with Aeromonas spp., E. coli bacteraemia was more often associated with less severe underlying conditions, a community-acquired infection (74%), and a urinary tract (52%) or abdominal (27%) origin and had a 30-d case fatality rate of 24%. P. aeruginosa bacteraemia occurred mainly in patients with severe underlying conditions, was associated with nosocomial infection (69%), and had a 30-d case fatality rate of 43%. In conclusion, Aeromonas spp. bacteraemia is a serious infection that should be considered in patients with chronic liver disease or neoplasm. It may occur in the elderly and as a nosocomial infection, and differs in clinical findings from bacteraemia due to other common pathogens.