Background and importance Concern about emerging pollutants, including pharmaceuticals, has been growing in recent decades. Antibiotics receive particular attention because of the problem of antibiotic resistance. Hospital pharmacists play an important role in the antibiotic stewardship programme, aiming to reduce antibiotic resistance.

Wastewater treatment plants (WWTPs) were not designed to eliminate pharmaceuticals. In fact, the effluent from these WWTPs frequently shows the presence of several antibiotics, including quinolones. The presence of human pathogens and a wide diversity of environmental bacteria provide the opportunity for transferring resistance factors between bacteria.

Among the quinolones, ciprofloxacin has received preferential attention. It is one of the substances included in the Surface Water Watch List under the European Union Water Framework Directive.

The predicted no-effect concentration (PNEC) is the concentration of a chemical which marks the limit at which below no adverse effects are expected. The PNEC for ciprofloxacin is 0.064 µg/L and 0.5 µg/L for norfloxacin. When concentrations exceed the PNEC, the water is denoted as being ‘at risk’ for resistance selection.

Spain is the European country ranked fourth in terms of consumption of quinolones.

Aim and objectives In this study we aimed to review the presence of quinolones in WWTP effluent (treated) in Spain.

Material and methods We used the pharmaceutical database published by the German Environment Agency, Umweltbundesamt, which collects all published information about the presence of pharmaceuticals in different environmental matrices.

The database was downloaded on 28 September 2021. We selected data regarding quinolones in WWTP effluent (treated) samples from Spain. We looked to see if measured concentrations were above the PNECs.

Results We found 25 reports of norfloxacin (2 above PNEC) and 47 for ciprofloxacin (31 above PNEC). The highest concentration for ciprofloxacin was 5.69 µg/L (Madrid) and 0.98 µg/L for norfloxacin (Seville). There were no data for levofloxacin or other quinolones.

Conclusion and relevance In Spain, 65% of ciprofloxacin and 8% of norfloxacin samples leaving WWTPs show a concentration >PNEC, and thus may be contributing to the development of quinolone-resistant bacteria. More data are needed to describe the effects and fate on the environment. It is necessary to increase awareness about quinolone pollution among hospital pharmacists to help reduce its consumption.

Conflict of interest No conflict of interest