Antimicrobial Resistance Information for Water Professionals: Why We Should Care?

Antimicrobial resistance (AMR) makes diseases more difficult to treat and has been spreading worldwide. It is considered a major public health concern. Over the last two decades, numerous projects investigated the occurrence of AMR, especially antibiotic resistance, in wastewater. In 2023, several papers (e.g., Berglund et al., 2023; Wang & Smith, 2023; Zhao et al., 2023) reported the detection of antibiotic-resistant genes (ARGs) and mobile genetic elements (MGEs) in wastewater, resulting in negative news stories and media inquiries at water resource recovery facilities (WRRFs) about AMR and potential risks from wastewater or biosolids (Wigglesworth, 2023). In addition, the Centers for Disease Control and Prevention (CDC) has expressed interest in including wastewater-based surveillance (WBS) of AMR targets in its National Wastewater Surveillance System, which will lead to continued focus on AMR. This presentation is intended to help inform the water sector as attention to this complex topic grows. It provides a summary of concepts related to antimicrobial and antibiotic resistance and the current state of the science related to antibiotic resistance at WRRFs. It highlights the following take home messages:

*Antibiotic-resistant bacteria (ARB) and ARGs are widely detected, including in natural environments and food, but their associated human health risks remain poorly understood and inadequately characterized.

*The risk of getting infected by ARB is not greater than the risk of getting infected by the same antibiotic-susceptible bacterium. Humans are exposed to millions of microbes with antibiotic-resistant traits every day via natural and necessary activities, such as the ingestion of water and food (Pepper et al., 2018). Most of these exposures do not cause infections.

*Antibiotic-resistant bacteria and ARGs are detected at WRRFs, but treatment processes, including coagulation, clarification, filtration, disinfection, and anaerobic digestion, generally reduce their levels.

*The Global Water Pathogen Project (2019) estimates that conventional WRRFs reduce the types of ARGs observed and their numbers in raw wastewater by approximately 33% to 98%. Though some ARGs and mobile genetic elements (such as integrons) are not reduced.

*Current practices for wastewater and municipal drinking water treatment are adequate to prevent enteric bacterial infections from ARB via drinking water.

*Workers at WRRFs could be exposed to ARB and ARGs through contact with wastewater, solids, and bioaerosols. The associated risks are uncertain but can be mitigated by following the worker safety recommendations of the CDC (n.d.-a) and WEF (2020).

*Wastewater-based surveillance is an emerging approach to complement public health data, but is not intended to inform risk assessment from wastewater exposure.

*Water resource recovery facilities are important critical control points and are one of the most effective means of removing or reducing the occurrence of ARB and ARGs in wastewater and the environment.