Pharmacokinetic model of human exposure to ciprofloxacin through consumption of fish

Fluoroquinolones are broad-spectrum antibiotics that accumulate in the environment. To assess human exposure through the food chain, we developed a pharmacokinetic model of fluoroquinolone accumulation in fish and a human pharmacokinetic model to predict gastrointestinal concentrations of ciprofloxacin, a common fluoroquinolone, following consumption of fish. At 70 ng/L ciprofloxacin, the average in North American surface waters, the fish steady-state concentration was calculated to be 7.5 x 10-6 mu g/g. Upon human consumption of the FDA -recommended portion of 113 g of fish containing this ciprofloxacin level, the predicted human intestinal concentration was 2 x 10-6 mu g/mL. At 4 x 106 ng/L (4 mu g/mL) ciprofloxacin, the highest recorded environmental measurement, these numbers were 0.42 mu g/g in fish and 0.1 mu g/mL in the human intestine. Thus, based on the ciprofloxacin MIC for E. coli of 0.13 mu g/mL, background environmental ciprofloxacin levels are unlikely to be problematic, but environmental pollution can result in high intestinal levels that may cause gut dysbiosis and antibiotic resistance.