Occurrence and Removal of Antibiotics, Antibiotic-Resistance Genes and Bacterial Communities in Hospital Wastewater

Hospital wastewater contains a variety of human-related antibiotics and pathogens, which makes the treatment of hospital wastewater essential. However, there is a lack of research on these pollutants in hospital wastewater treatment plants. In this study, the characteristics and removal of antibiotics and antibiotic resistance genes (ARGs) in independent treatment processes of hospitals of different scales (primary hospital H1, secondary hospital H2, and tertiary hospital H3) were investigated. The occurrence of antibiotics and ARGs in wastewater from three hospitals varied greatly. The first-generation cephalosporin cefradine was detected at a concentration of 2.38 μg/L in untreated wastewater of H1, while the fourth-generation cephalosporin cefepime had the highest concentration, 540.39 μg/L, in H3. Ofloxacin was detected at a frequency of 100% and had removal efficiencies of 44.2%, 51.5%, and 81.6% for H1, H2, and H3, respectively. The highest relative abundances of the β-lactam resistance gene bla GES-1 (1.77×10 -3 copies/16S rRNA), quinolone resistance gene qnrA (8.81×10 -6 copies/16S rRNA), and integron intI1 (1.86×10 -4 copies/16S rRNA) were detected in the treated wastewaters. The concentrations of several ARGs were increased in the treated wastewater (e.g., bla OXA-1 , bla OXA-10 and bla TEM-1 ). Several pathogenic or opportunistic bacteria (e.g., Acinetobacter , Klebsiella , Aeromonas , and Pseudomonas ) were observed with high relative abundances in the treated wastewater. These results suggested the co-occurrence of novel antibiotics, ARGs, and antibiotic-resistant pathogens in hospital wastewater that may spread into the receiving water environment.