Epidemiology of ciprofloxacin-resistant Pseudomonas aeruginosa in a veterans affairs hospital.

This study was performed to identify risk factors for the nosocomial acquisition of ciprofloxacin-resistant Pseudomonas aeruginosa (CRPA) in a Veterans Administration hospital between January 1994, and March 1995. The study was a retrospective comparison of host factors and in-hospital exposures of patients who acquired nosocomially CRPA and ciprofloxacin-sensitive P. aeruginosa (CSPA). Participants included 42 adult patients with nosocomial CRPA acquisition and 52 adult patients with nosocomial CSPA acquisition. Before pseudomonal acquisition, antecedent ciprofloxacin receipt (50% compared with 8%; odds ratio [OR], 12; p = 0.001), the presence of an indwelling airway (36% compared to 17%; OR, 2.6; p = 0.04), and documented antecedent infection (74% compared to 52%; OR, 2.6; p = 0.03) were significantly associated with acquisition of CRPA. On multivariate analysis, antecedent ciprofloxacin receipt (OR, 16.8; p = 0.0001) and presence of an indwelling airway (OR, 10.5; p = 0.009) remain as significant associations. Furthermore, the test of significance confirmed synergy between these two factors. Antecedent ciprofloxacin therapy and indwelling airway act independently and synergistically to promote CRPA acquisition.