PRESENCE OF ANTIBIOTIC RESISTANT BACTERIA IN URBAN FLOODWATER OF PENINSULAR CHARLESTON, SC

Flooding is a common occurrence in the Charleston peninsula given its geographic location along the Atlantic coastline and its environmental history of filling marshes for development. Much of this flooding occurs either from rainfall (typically, >2.5 cm/day) and/or high/king tide (typically, MLLW >7 ft) related flooding of low-lying areas. These floodwaters funnel different types of urban pollutants into the coastal waters. Contaminants such as heavy metals and fecal bacteria are known to be present in stormwater runoff, but the prevalence of antibiotic-resistant bacteria (ARB) in the floodwater is unknown. The goal of this study is to assess the public and environmental health risks associated with floodwater. Floodwater was collected during rainfall and high/king tide events with the main objective of assessing the presence of ARB in floodwater under different conditions. The floodwater in the Charleston peninsula included runoff from rainfall, floodwater from the marsh during high tides, and a combination of both events. Our preliminary results confirm the presence of high concentrations of fecal indicator bacteria (fecal coliforms, E. coli, and enterococcus) in the floodwaters of both Charleston and the Francis Marion National Forest. Tidal floodwater contained higher fecal indicator bacteria compared with stormwater runoff. Trace metals commonly associated with floodwater were also analyzed in these samples. Multiple flood-prone locations in the Charleston peninsula and a first-order headwater stream in the Francis Marion National Forest were sampled to represent urban floodwater and forested runoff samples, respectively. Floodwater from some of our sample sites confirmed the presence of ampicillin and amoxicillin-resistant bacteria. Trace metals of concern (e.g., Cr, Zn) were present in all floodwaters, but their concentrations were dependent on whether the source was stormwater or tidal floodwater. The presence of ARB in floodwater is of concern to the local communities as they are routinely exposed to these floodwaters leading to poor health outcomes. Additionally, the increase in coastal flooding events exacerbated by changing climate makes this problem serious.