Reduction of fluoroquinolone use is associated with a decrease in methicillin-resistant Staphylococcus aureus and fluoroquinolone-resistant Pseudomonas aeruginosa isolation rates: a 10 year study

High rates of methicillin-resistant Staphylococcus aureus (MRSA) and fluoroquinolone-resistant Pseudomonas aeruginosa may be related, in part, to the overuse of fluoroquinolones. The objective was to analyse and correlate long-term surveillance data on MRSA and fluoroquinolone-resistant P. aeruginosa rates and antibiotic consumption after implementation of an institution-wide programme to reduce fluoroquinolone use. An interrupted time series/quasi-experimental study of monthly fluoroquinolone use and MRSA and fluoroquinolone-resistant P. aeruginosa isolation rates was carried out in a tertiary hospital during three periods: pre-intervention (January 2000August 2005), intervention (September 2005March 2006), and post-intervention (March 2006March 2010). The effect of the intervention on the consumption of fluoroquinolones and bacterial resistance was assessed using segmented regression analyses. Mean monthly fluoroquinolone consumption dropped by 29.1 defined daily doses per 1000 patient-days (DDD/1000 PD) (95 CI 13.145.9; P0.0005) from a mean of 148.2 to 119.1 DDD/1000 PD during the intervention period. A sustained and significant decrease in fluoroquinolone consumption of 0.95 DDD/1000 PD/month was also observed during the post-intervention period (P0.0002). During the post-intervention period the rate of fluoroquinolone-resistant P. aeruginosa continuously decreased, from a mean of 42 to 26, with a constant relative change rate of 13/year (95 CI 19 to 5, P0.001). A decrease in the MRSA rate was observed during the intervention period, from a mean resistance rate of 27 to 21 (P0.0001). We showed the sustained impact of a fluoroquinolone control programme on the reduction of fluoroquinolone use with a significant decrease in fluoroquinolone-resistant P. aeruginosa and MRSA rates over 4 years.