Stream Monitoring using Antibiotic Resistance Detection and Microbial Fingerprinting Methods as Indicators of Anthropogenic Contamination

This study examined the use of antibiotic resistance and antibiotic resistant gene detection in addition to molecular bacterial fingerprinting as an alternative gauge of anthropogenic influence on stream water. A transect of a southern Wisconsin creek spanning a treated effluent discharge was analyzed for resistance to the common antibiotic tetracycline over three years. The percent of resistant heterotrophic bacteria was significantly elevated downstream of the wastewater discharge (p= 0.0016). Antibiotic resistance detection was a more reliable indicator of human impact than assays focusing on traditional indicators. Tetracycline resistance genes were detected downstream of the wastewater discharge and the gene copy concentrations of two genes were significantly elevated in downstream samples. In addition, UV disinfection did not lower the concentrations of tetracycline resistance genes added to the stream. Bacterial community compositions along the transect, measured by molecular fingerprinting techniques, were altered due to the addition of wastewater. Heightened antibiotic resistance profiles offer a conservative indication of anthropogenic impact on surface waters.