Clinical impact of imipenem-resistant Pseudomonas aeruginosa bloodstream infections

Abstract

To describe the incidence and clinical characteristics of imipenem-resistant (IR) Pseudomonas aeruginosa bacteraemia. We performed a retrospective study including all episodes of IR P. aeruginosa bacteraemia seen from January 2003 to December 2005 in a tertiary teaching hospital. There were 108 episodes of IR P. aeruginosa bacteraemia, which represented an incidence of 0.14 episodes per 1000 patient-days in 2003 and 0.11 episodes per 1000 patient-days in 2005. 83 of the episodes (77%) were nosocomially acquired. Most of patients had at least one underlying disease and had previously received antimicrobial treatment. The most frequent source was the urinary tract (31%), followed by unknown origin (22%). A total of 23 (21%) episodes were polymicrobial and 51 (47%) were caused by multidrug-resistant strains. The independent risk factors for mortality from IR P. aeruginosa bloodstream infection were a high-risk source of the bacteraemia (OR: 4.6; 95% CI 1.7-12.4; p=0.01), and presentation with severe sepsis (OR: 2.8; 95% CI 1-7.8; p=0.05). Our study shows that the rates of IR P. aeruginosa bacteraemia remained stable throughout the study period. The source of bacteraemia and the clinical presentation with severe sepsis were the main determinants of the prognosis.