Determination of antimicrobial concentration and associated risk in water sources in West Bengal state of India

The presence of antimicrobials in wastewater (WW), surface water (SW), groundwater (GW), and even in potable water from treatment plants has been reported from many countries. Their presence in the water sources is causing the rise and spread of antimicrobial resistance (AMR), thereby threatening our public health, global economy, and development. This necessitates the constant monitoring of these compounds along with the evaluation of their associated risk to aquatic organisms. In this study, GW, WW, and SW samples from different parts of West Bengal (India) were analyzed using the SPE-HPLC-DAD method for detecting two frequently used fluoroquinolones (ciprofloxacin, CIP and ofloxacin, OFL). The highest concentration of CIP and OFL was 5.75 μg/L (GW) and 17.84 μg/L (WW), respectively. The antimicrobial activity was determined against Escherichia coli and Staphylococcus aureus isolates from WW against CIP, which showed that Escherichia coli and Staphylococcus aureus had developed ~ 69 and ~ 12 times resistance compared to their respective pure strains. The risk assessment showed that CIP poses an insignificant threat to fish and Daphnia (RQ < 1) but a significant threat to green algae and Microcystis aeruginosa (RQ> > 1). OFL concentration also poses a great threat to all the organisms for which the assessment was made (RQ> > 1). Moreover, risk assessment in terms of AMR showed that the present level of these antimicrobials in different water sources could cause the development of resistance among the microbial community (RQ > 1). These results emphasize the need for constant monitoring of pharmaceutical compounds, especially antimicrobials, to be kept under check.