Distribution of Tetracycline-Resistant Bacteria Within the Fort Phantom Hill Reservoir Watershed

Tetracycline resistance genes have been reported to be abundant in bacteria in environments impacted by agriculture. The Fort Phantom Hill reservoir watershed in Jones and Taylor counties in Texas includes feedlots, rangeland, and row crop agriculture with manure-treated soils. We hypothesized that tetracycline-resistant coliforms could be present throughout the watershed. To investigate our hypothesis, samples were taken from the sediment of seven sites within the watershed between June 2022-August 2023. Tetracycline-resistant coliforms and non-coliforms were isolated from six out of seven sites. The highest relative abundance of tetracycline-resistant isolates was found at a site at Cedar Creek, with 0.15% resistance. Additionally, the highest relative abundance of tetracycline resistance among lactose fermenters was at a site at Elm Creek (3.38%) followed by a second site at Cedar Creek (0.07%). From a representative sample of tetracycline-resistant isolates across all sites, the tetB genotype was the most common (45.95%, n=37), followed by tetA as determined by multiplex PCR products. Additionally, four multi-drug resistant strains of Escherichia were identified: CCN-113, CCN-251, CCN-109, and ELM-161. A resistance plasmid was extracted from CCN-251 carrying dhfr1 and sulII resistance genes. Monitoring of the spread of antimicrobial resistance genes through surface water in the Fort Phantom Hill Watershed provides data to support the need for antibiotic stewardship in this region.