Impact of treated wastewater irrigation on antibiotic resistance in the soil microbiome

Abstract

The reuse of treated wastewater (TWW) for irrigation is a practical solution for overcoming water scarcity, especially in arid and semiarid regions of the world. However, there are several potential environmental and health-related risks associated with this practice. One such risk stems from the fact that TWW irrigation may increase antibiotic resistance (AR) levels in soil bacteria, potentially contributing to the global propagation of clinical AR. Wastewater treatment plant (WWTP) effluents have been recognized as significant environmental AR reservoirs due to selective pressure generated by antibiotics and other compounds that are frequently detected in effluents. This review summarizes a myriad of recent studies that have assessed the impact of anthropogenic practices on AR in environmental bacterial communities, with specific emphasis on elucidating the potential effects of TWW irrigation on AR in the soil microbiome. Based on the current state of the art, we conclude that contradictory to freshwater environments where WWTP effluent influx tends to expand antibiotic-resistant bacteria (ARB) and antibiotic-resistant genes levels, TWW irrigation does not seem to impact AR levels in the soil microbiome. Although this conclusion is a cause for cautious optimism regarding the future implementation of TWW irrigation, we conclude that further studies aimed at assessing the scope of horizontal gene transfer between effluent-associated ARB and soil bacteria need to be further conducted before ruling out the possible contribution of TWW irrigation to antibiotic-resistant reservoirs in irrigated soils.

Effect of Ampicillin, Streptomycin, Penicillin and Tetracycline on Metal Resistant and Non-Resistant Staphylococcus aureus

“…The incidence of resistant microorganisms is monitored primarily in hospitals, but much higher risk is present in the soil and waters [3]. Resistance, generated in the external environment, is a natural development of every live system.…”

Wastewater Irrigation Increases the Abundance of Potentially Harmful Gammaproteobacteria in Soils in Mezquital Valley, Mexico

“…The release of antibiotics together with the human-linked microbiota might be particularly important for the emergence of newly evolving antibiotic-resistant pathogens (1,14). Environmental reservoirs for antibiotic resistances, especially those affected by anthropogenic activities (e.g., application of manure), can serve as "hot spots" for the spread of antibiotic resistance genes and antibiotic-resistant bacteria through food and water, with unknown consequences for human health (14)(15)(16). D'Costa and colleagues indicated that soil could serve as an underestimated reservoir for antibiotic resistance that has already emerged or has the potential to emerge in clinically important bacteria (17).…”

Do antibiotics have environmental side-effects? Impact of synthetic antibiotics on biogeochemical processes

“…Similarly, the spread of antibiotic resistance in hospitals and in the environment has been extensively discussed and studied with over 850 publications. Many of the studies report an inventory of antibiotic resistance genes (Nesme et al 2014) and many address bacteria in aquatic environments (for review see Kümmerer 2009b) or soils (Gatica and Cytryn 2013). The resistance of bacterial species used as fecal indicators was also often investigated (Luczkiewicz et al 2013;Servais and Passerat 2009).…”