Examining the Impact of Environmental Factors on Fecal Contamination, Antibiotic Resistance, and Water Quality in Coastal Habitats of North Carolina

Aquatic environments provide a tremendous amount of ecosystem services to coastal communities. Fecal contamination from wastewater treatment systems and infrastructure is of large public health risk for the potential development of antimicrobial resistant (AMR) pathogens. IDEXX culturing, Kirby Bauer Disk Diffusion tests, and digital droplet PCR were used to characterize fecal contamination, AMR, and their connections in the coastal waters of North Carolina. Larger rainfall events (i.e., greater than 1 cm) resulted in smaller differences between influent and effluent fecal indicator bacteria concentrations, likely from wastewater treatment plants running their systems faster to anticipate the rainwater. Viable multi-drug resistant bacteria were cultured from environmental King Tide samples using the Kirby Bauer method. Tidal stage had a significant negative correlation with log-adjusted E. coli concentrations (r=-0.61, p<0.05), suggesting that at lower tidal height, bacterial concentrations are higher. Log-transformed KPC and HF183 concentrations positively correlated with each other (r=0.73, p<0.05). E. coli concentrations positively correlated with KPC (r=0.73, p<0.05) and HF183 (r=0.62, p<0.05) when all were log-transformed. These correlations statistically anchor culture-dependent and independent approaches with each other, which can inform method standardization for AMR monitoring. The findings provide evidence of AMR in coastal waters of North Carolina and provide an approach to the standardization of methods to develop more robust AMR monitoring in aquatic environments.