Impact of reclaimed water irrigation on antibiotic resistance in public parks, Beijing, China

The abundance and distribution of antibiotics and antibiotic resistance genes (ARGs) in soils from six parks using reclaimed water in Beijing, China, were characterized. Three classes of commonly used antibiotics (tetracycles, quinolones, and sulfonamides) were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The highest concentrations of tetracyclines and quinolones were 145.2 μg kg−1 and 79.2 μg kg−1, respectively. Detected tetG, tetW, sulI, and sulII genes were quantified by quantitative PCR. ARGs exhibited various abundances for different park soils. The integrase gene (intI1) as an indicator of horizontal gene transfer potential was also detected in high abundance, and had significant positive correlation with tetG, sulI, and sulII genes, suggesting that intI1 may be involved in ARGs dissemination. Both sulII and intI1 clones had high homology with some classes of pathogenic bacteria, such as Klebsiella oxytoca, Acinetobacter baumannii, Shigella flexneri, which could trigger potential public health concern. [Display omitted] •Reclaimed water irrigation could increase the concentration of antibiotics and ARGs in urban park soils.•ARGs can be persistent in the irrigated park soils, even without antibiotic selection pressure.•Both sulII and intI1 clones had high homology with some classes of pathogenic bacteria. The release of residual antibiotics and ARGs from reclaimed water could result in the proliferation of ARGs in irrigated park soils.