Impact of syndrome-specific antimicrobial stewardship interventions on use of and resistance to fluoroquinolones: An interrupted time series analysis.

Background: Fluoroquinolones are often prescribed unnecessarily and are an important risk factor for infection with fluoroquinolone-resistant gram-negative bacilli and Clostridioides difficile.

Methods: We conducted a quasi-experimental study to determine the impact of sequential syndrome-specific stewardship interventions on use of and resistance to fluoroquinolones in a tertiary care hospital. An initial 2-year intervention focused on reducing treatment of asymptomatic bacteriuria and ensuring concordance of urinary tract infection treatment with guidelines. A second 5-year intervention focused on limiting overuse of fluoroquinolones for health care-associated pneumonia in conjunction with a formal stewardship program. The primary outcomes were fluoroquinolone use and changes in use over time analyzed by segmented regression analysis.

Results: The asymptomatic bacteriuria and urinary tract infection intervention resulted in a significant reduction in fluoroquinolone use, with a significant change from an increasing to a decreasing rate of use (change in slope of quarterly defined daily doses/1,000 patient days -15.3, P < .01). The health care-associated pneumonia intervention resulted in a continued significant reduction in fluoroquinolone use (rate ratio = 0.68, P < .01). During the interventions, fluoroquinolone susceptibility increased significantly in Pseudomonas aeruginosa, but not in Escherichia coli, Klebsiella spp., or C difficile.

Conclusions: Antimicrobial stewardship interventions focused on specific syndromes may be effective in reducing fluoroquinolone use. In our hospital, reduction in fluoroquinolone use resulted in increased fluoroquinolone susceptibility in P aeruginosa, but not other Enterobacteriaceae or C difficile.