Occurrence and removal of antibiotics, antibiotic resistance genes, and bacterial communities in hospital wastewater

Hospital wastewater contains a variety of human antibiotics and pathogens, which makes the treatment of hospital wastewater essential. However, there is a lack of research on these pollutants at hospital wastewater treatment plants. In this study, the characteristics and removal of antibiotics and antibiotic resistance genes (ARGs) in the 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 from H1, while the fourth-generation cephalosporin cefepime had the highest concentration, 540.39 μg/L, at H3. Ofloxacin was detected at a frequency of 100% and had removal efficiencies of 44.2%, 51.5%, and 81.6% at 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), the quinolone resistance gene qnrA (8.81×10 −6 copies/16S rRNA), and the integron intI1 (1.86×10 −4 copies/16S rRNA) were detected in the treated wastewater. 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 at high relative abundances in the treated wastewater. These results suggested the co-occurrence of antibiotics, ARGs, and antibiotic-resistant pathogens in hospital wastewater, and these factors may spread into the receiving aquatic environment.