Occurrence of antibiotic resistant bacteria in urban karst groundwater systems

Authors: KAISER, RACHEL - Tennessee Technological University; POLK, JASON - Western Kentucky University; DATTA, TANIA - Tennessee Technological University; Parekh, Rohan; Agga, Getahun

Submitted to: Water
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2022
Publication Date: 3/18/2022
Citation: Kaiser, R.A., Polk, J., Datta, T., Parekh, R.R., Agga, G.E. 2022. Occurrence of antibiotic resistant bacteria in urban karst groundwater systems. Water. 14(6). Article 960. https://doi.org/10.3390/w14060960.
DOI: https://doi.org/10.3390/w14060960

Interpretive Summary: Karst groundwater systems are prone to contaminants such as antibiotic resistant bacteria, mainly due to the lack of natural filtration from the surface to the subsurface. Once introduced to the groundwater system, antibiotic resistant bacteria can be transported throughout the aquifer via the conduit systems and through the karst matrix. The level of antibiotic resistant bacteria increases from its base flow level during precipitation events that introduce surface bacteria from human and agriculturally impacted landscape. Groundwater systems are sources of drinking water to the public directly or through their recharge into surface water that provides drinking water to local communities. Periodic monitoring of the drinking water sources such as a groundwater system for the presence of antibiotic resistant bacteria is essential to protect the public health. A year-long monitoring of ten sites in the city of Bowling Green, KY, and a cross-sectional sampling of ground water sites in the Tampa Metropolitan area, FL, revealed the persistent presence of antibiotic resistant bacteria of public health importance. The results can be used to develop monitoring programs to ensure the safety of drinking water.

Technical Abstract: Antibiotic resistance is a global concern for human, animal, and environmental health. Many studies have identified wastewater treatment plants and surface waters as major reservoirs of antibiotic resistant bacteria (ARB) and genes (ARGs). Yet their prevalence in urban karst groundwater systems remains largely unexplored. Considering the extent of karst groundwater use globally, and the growing urban areas in these regions, there is an urgent need to understand antibiotic resistance in karst systems to protect source water and human health. This study evaluated the prevalence of ARGs associated with resistance phenotypes at 10 urban karst features in Bowling Green, Kentucky weekly for 46 weeks. To expand the understanding of prevalence in urban karst, a spot sampling of 45 sites in the Tampa Bay Metropolitan area, Florida was also conducted. Specifically, this study considered tetracycline and extended spectrum beta-lactamase (ESBLs) producing, including third generation cephalosporin, resistant E. coli, and tetracycline and macrolide resistant Enterococcus spp. across the 443 Kentucky and 45 Florida samples. A consistent prevalence of clinically relevant and urban associated ARGs were found throughout the urban karst systems, regardless of varying urban development, karst geology, climate, or landuse. These findings indicate urban karst groundwater as a reservoir for antibiotic resistance, potentially threatening human health.