Influence of fluoroquinolone purchasing patterns on antimicrobial expenditures and Pseudomonas aeruginosa susceptibility

The influence of using ofloxacin in place of ciprofloxacin on hospital fluo roquinolone expenditures, total antimicrobial expenditures, and susceptibil ity of Pseudomonas aeruginosa to fluoroquinolones was studied. Hospitals with fluoroquinolone expenditures of at least $1 per occupied bed per year were administered annual surveys covering the years 1993 through 1996. The two most recent consecutive years of data were compared among hos pitals that used ciprofloxacin as their primary fluoroquinolone during both years (group 1), hospitals whose ofloxacin purchases increased from accoun ting for less than or equal to 25% of total fluoroquinolone expenditures du ring year 1 to accounting for >25% during year 2 (group 2), and hospitals w hose ofloxacin purchases accounted for at least 25% of total fluoroquinolon e expenditures for both years (group 3). A total of 109 hospitals were included in the study. Most hospitals spent m ore on fluoroquinolones and total antimicrobials in year 2 than year 1. Gro up 3 hospitals had a significant increase in expenditures for fluoroquinolo nes and nonfluoroquinolone antipseudomonal antimicrobials. Group 2 hospital s did not realize antimicrobial cost savings and had higher rates of Pseudo monas aeruginosa resistance than hospitals that used ciprofloxacin. Whether a hospital changed its pattern of ciprofloxacin and ofloxacin purch asing was not significantly associated with expenditures for fluoroquinolon es, non-fluoroquinolone-antimicrobal agents, or all antimicrobials. Suscept ibility of P. aerginosa to ciprofloxacin was lower in hospitals with greate r proportions of ofloxacin use. Individual hospital, ciprofloxacin expendit ures, and study year were found to be predictive of P. aerginosa susceptibi lity to ciprofloxacin among all pooled hospitals.