Significant differences in usage of antibiotics in three Chinese cities measured by wastewater-based epidemiology.

Antibiotic use, particularly inappropriate use by irrational prescribing or over-the-counter purchases, is of great concern for China as it facilitates the spread of antibiotic resistances. In this study, we applied wastewater-based epidemiology (WBE) to monitor the total consumption of eight common antibiotics in three cities in northern, eastern and southern China. Wastewater samples were successively collected from 17 wastewater treatment plants including weekdays and weekends spanning four seasons between 2019 and 2021. The concentration of antibiotics and their corresponding metabolites showed a significant correlation, confirming the measured antibiotics were actually consumed. Different seasonal trends in antibiotic use were found among the cities. It was more prevalent in the winter in the northern city Beijing, with the high antibiotic consumption attributed to peak influenza occurrence in the city. This is clear evidence of irrational prescription of antibiotics since it's known that antibiotics do little to treat influenza. In terms of overall consumption, Foshan is significantly lower, thanks to warmer climate and higher use of herbal tea as a prevention measure. WBE estimates of antibiotic consumption were relatively comparable with other data sources, with azithromycin as the top antibiotic measured here. The studied cities had higher WBE estimated antibiotics consumption than results of previous studies in the literature. Monitoring antibiotic use in different areas and periods through WBE in combination with complementary information, can better inform appropriate antibiotic guideline policies in various regions and nations.