Heavy metal-antibiotic resistant bacteria in a lake recreational area

Abstract

We undertook this study to determine the impact of urbanization on the microbial content of waters of a major recreational area of Lake Champlain. We followed changes in the numbers of total coliforms, fecal coliforms, fecal streptococci, and ascertained resistance of coliforms to heavy metals and antibiotics. We determined the distribution of these bacterial indicators of pollution by examining water and sediment samples. We also surveyed changes in physical parameters such as pH, temperature, turbidity, and wind direction to evaluate their effect on the examined aquatic microbial population. The level of all standard microbial indices of pollution frequently exceeded acceptable levels for recreational waters. Sediment samples indicated prolonged deposition of microbial pollutants, but efforts to demonstrate their release from sediment by dislocation and resuspension were inconclusive. We confirmed the presence of a population of heavy-metal and antibiotic-resistant coliforms isolated from harbor waters. Eighty-four percent of the total coliforms isolated from harbor water samples were resistant to one or more antibiotics and 96% were resistant to two or more heavy metals. The presence of these antibiotic resistant properties in coliforms, as well as elevated fecal coliform and fecal streptococci counts in both water and sediment samples, suggests to us that the bay is polluted by human fecal matter. This pollution probably emanates from south harbor sources and affects the shores of the major northern bathing area. It constitutes a potential hazard to public health because of the geophysical nature of the harbor and the location of the pollution source.