Concentrations of ciprofloxacin in the world's rivers are associated with the prevalence of fluoroquinolone resistance in Escherichia coli: a global ecological analysis

BACKGROUND: Extremely low concentrations of ciprofloxacin may select for antimicrobial resistance. A recent global survey found that ciprofloxacin concentrations exceeded safe levels at 64 sites. In this study, I assessed if national median ciprofloxacin concentrations in rivers were associated with fluoroquinolone resistance in Escherichia coli.

METHODS: Spearman's regression was used to assess the country-level association between the national prevalence of fluoroquinolone resistance in E. coli and the median ciprofloxacin concentration in the country's rivers.

RESULTS: The prevalence of fluoroquinolone resistance in E. coli was positively correlated with the concentration of ciprofloxacin in rivers (ρ = 0.36; p = 0.011; n = 48).

DISCUSSION: Steps to reducing the concentrations of fluoroquinolones in rivers may help prevent the emergence of resistance in E. coli and other bacterial species.