Development of antibiotic resistance in bacteria of soils irrigated with reclaimed wastewater

Wastewater reclamation for municipal irrigation is an increasingly attractive option for extending water supplies. However, public health concerns include the potential for development of antibiotic resistance (AR) in soil bacteria after exposure to residual chemicals in reclaimed water. Though scientific studies have reported high levels of AR in soils irrigated with wastewater, these works often ignore the natural occurrence of soil AR. We are comparing AR patterns in soil Enterococcus isolated from water storage basins recharged with either reclaimed water or groundwater in central Arizona. Resistance to 16 antibiotics is being quantified from the soil surface (0-5 cm) to a depth of 30 cm. Results reveal that resistance to multiple antibiotics, including tetracycline, daptomycin, and erythromycin, exists in soils regardless of the water source (groundwater, reclaimed water). Though resistance patterns differ between bacteria isolated from soils from the two treatments, overall AR is not increased in soils exposed to reclaimed water. Comparing the development of AR in soil bacteria at these two sites will increase awareness of the environmental and public health impacts of using reclaimed water for irrigation of municipal areas.