Freshwater Biological Association, The Ferry House,

Antibiotics are used extensively in medicine and agriculture, and some of the resistant bacteria which develop find their way into lakes and rivers. It was decided to use antibiotic resistance as a convenient marker to study gene transfer in the natural environment. However, a preliminary survey of Windermere showed that there was a higher incidence of resistance in the bacteria isolated from the lake water than from the sewage effluent discharging into the lake. This unexpected result was followed by the more surprising finding that the incidence of resistance was even higher in the bacterial populations of two remote upland tarns. The results have important implications for those involved in examining the spread of antibiotic resistance into remote environments. Some of the technical problems in determining the antibiotic resistance profiles of aquatic bacteria are discussed