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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Water Management and Conservation Research » Research » Publications at this Location » Publication #256426
Title: Bacterial antibiotic resistance in soils irrigated with reclaimed municipal wastewater

Author
item McLain, Jean
item Williams, Clinton

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 9/12/2010
Publication Date: N/A
Citation: N/A

Interpretive Summary: Wastewater reclamation for municipal irrigation and groundwater recharge 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 fail to address the natural occurrence of AR in soil bacteria. The Gilbert Riparian Preserve in Gilbert, Arizona has been utilizing reclaimed municipal wastewater for groundwater recharge for nearly 20 years. We are comparing AR patterns in Gram positive (enterococci) and Gram negative (E. coli) soil bacteria isolated from sediments of the Riparian Preserve and comparing these to bacterial AR in sediments collected from a groundwater-filled pond. Resistance to 16 antibiotics is being quantified from the soil surface (0-5 cm) to a depth of 30 cm. Results reveal that, regardless of source water, high level resistance to multiple antibiotics, including tetracycline, vancomycin, penicillin, and erythromycin, exists in the bacterial populations, but overall AR in the Riparian Preserve sediments is not higher than sediments exposed only to groundwater. Comparing the development and transport of AR in soil bacteria at these two sites will increase current understanding of environmental and public health impacts of using reclaimed water for irrigation and recharge.

Technical Abstract: Wastewater reclamation for municipal irrigation and groundwater recharge 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 fail to address the natural occurrence of AR in soil bacteria. The Gilbert Riparian Preserve in Gilbert, Arizona has been utilizing reclaimed municipal wastewater for groundwater recharge for nearly 20 years. We are comparing AR patterns in Gram positive (enterococci) and Gram negative (E. coli) soil bacteria isolated from sediments of the Riparian Preserve and comparing these to bacterial AR in sediments collected from a groundwater-filled pond. Resistance to 16 antibiotics is being quantified from the soil surface (0-5 cm) to a depth of 30 cm. Results reveal that, regardless of source water, high level resistance to multiple antibiotics, including tetracycline, vancomycin, penicillin, and erythromycin, exists in the bacterial populations, but overall AR in the Riparian Preserve sediments is not higher than sediments exposed only to groundwater. Comparing the development and transport of AR in soil bacteria at these two sites will increase current understanding of environmental and public health impacts of using reclaimed water for irrigation and recharge.