Development SPE-LC-MS/MS method for determination of WHO AWaRe Reserve antibiotics in hospital wastewater

Overuse and inadequate legal regulation of the use of antibiotics have led to antimicrobial resistance, which threatens healthcare by reducing the effectiveness of treatments and promoting multidrug-resistant "superbugs". The World Health Organization created the AWaRe (Access, Watch, Reserve) classification to categorize antimicrobials according to their therapeutic value, emphasizing prudent use. The most important group in terms of protecting effectiveness is the Reserve group. The aim of the study was to develop a method for the determination of the following Reserve antibiotics in hospital wastewater: aztreonam, linezolid, meropenem, tigecycline, vaborbactam, cilastatin, fosfomycin, and ceftazidime. Twenty-six extraction procedures were tested and the one with the best recoveries for all antimicrobials (31.5-103.7%) was selected. The extracts were analyzed by liquid chromatography-tandem mass spectrometry. The method was validated and applied to the determination of the selected pharmaceuticals in effluents from 16 hospitals in Poland, with Reserve antibiotics detected in each sample at concentrations ranging from 1.89 ng L^- 1 to 22.49 µg L^- 1. This is the first country-scale methodological study on Reserve antibiotics in hospital wastewater, emphasizing the need for early environmental monitoring and the potential integration of such strategies into healthcare systems to mitigate the global antimicrobial resistance crisis.