Hospital and community fluoroquinolone use and resistance in Staphylococcus aureus and Escherichia coli in 17 US hospitals

Background. Fluoroquinolones are widely prescribed in hospitals and the community. Previous studies have shown associations between fluoroquinolone use and isolation of fluoroquinolone-resistant Eshcerichia coli and methicillin-resistant Staphylococcus aureus (MRSA). We performed an ecologic-level study to determine whether variability in hospital percentages of fluoroquinolone-resistant E. coli and MRSA were associated with fluoroquinolone use in hospitals and their surrounding communities. Methods. We measured fluoroquinolone use in 17 US hospitals and their surrounding communities in the year 2000. Data on fluoroquinolone use in hospitals was electronically extracted from billing data. Data on fluoroquinolone use in communities was obtained from IMS health data for all prescriptions filled in pharmacies within a 16-km radius of each hospital. We used hospital antibiograms to determine the percentage of isolates that were fluoroquinolone-resistant E. coli and MRSA, and we performed linear regression to determine the relationship between percentage of resistant isolates and fluoroquinolone use in hospitals and their surrounding communities. Results. There was a significant association between total fluoroquinolone use within hospitals and percentage of S. aureus isolates that were MRSA (r = 0.77; P=.0003) and between total fluoroquinolone use in the community (r = 0.77 P = 0003) and percentage of E. coli isolates that were fluoroquinolone-resistant E. coli (r = 0.68; P = .003) Population density within the 16-km radius also correlated with MRSA percentage ( r= 0.57; P = .015) and fluoroquinolonerp Pp. 015 resistant E. coli percentage (r = 0.85; P =.002) but associations between total fluoroquinolone use and resistance (r= 0.85 P = .002) remained significant after adjustment for population density. Conclusions. In this ecologic analysis, we found associations between fluoroquinolone use in hospitals and methicillin resistance in S. aureus and between fluoroquinolone use in communities and fluoroquinolone resistance in E. coli in hospitals. Antimicrobial use in hospitals and communities may have different relative importance with regard to resistance in different pathogens encountered in hospitals.