Distribution of Antibiotic Resistance Genes and Bacteria from six Atmospheric Environments

Antibiotic resistance genes (ARGs), as an emerging environmental pollutant, have received widespread attention. Among the different atmospheric environments including wastewater treatment plant (fine screens and sludge thickener), bathroom, laboratory, hospital and outdoor, the highest total concentration of ARGs is detected in the haze outdoor (9×105 copies/m3), while the lowest is in the bathroom atmosphere (4.2×104 copies/m3). Furthermore, β-lactam ARGs are found to be the dominant ARGs in these 6 atmospheric environments. Due to the large number and widespread use of antibiotics, the airborne ARGs in hospital have the highest diversity and equitability. The β-lactam ARGs are significantly positively correlated with sulfonamides ARGs, indicating the mechanism of co-resistance that is resistant to different resistance determinants on the same genetic elements. The network analysis provides potential host information between the airborne ARGs and the coexisted microbial taxa. Sphingomonas and Bradyhizoblum strains presumably host for tetracycline and β-lactam ARGs, respectively. Furthermore, the human body obtains the highest dose rate of ARGs through food intake (105 copies/d/kg), followed by drinking water (103 copies/d/kg), and finally the respiratory route (1-10 copies/d/kg). However, both the exposure dose of blaOXA-1 in any of the 6 atmospheric environments and that of blaTEM-1 in any of the 5 atmospheric environments are higher than the exposure dose of blaSHV (-0.62 copies/kg/d) and that of tetX (1.38 copies/kg/d) from water. Therefore, we should not ignore the exposure risk of ARGs in the atmospheric environment while paying attention to the exposure risk of ARGs in water and food.