Dissemination of antibiotic resistance determinants via sewage discharge from Davis Station, Antarctica
Discharge of untreated or macerated sewage presents a significant risk to Antarctic marine ecosystems by introducing non-native microorganisms that potentially impact microbial communities and threaten health of Antarctic wildlife. Despite these risks, disposal of essentially untreated sewage continues in the Antarctic and sub-Antarctic. As part of an environmental impact assessment of the Davis Station, we investigated carriage of antibiotic resistance determinants in Escherichia coli isolates from marine water and sediments, marine invertebrates (Laturnula and Abatus), birds and mammals within 10 km of the Davis sewage outfall. Class 1 integrons typical of human pathogens and commensals were detected in 12% of E. coli isolates. E. coli carrying these integrons were primarily isolated from the near shore marine water column and the filter feeding mollusc Laturnula. Class 1 integrons were not detected in E. coli isolated from seal (Miroungaleonina, Leptonychotes weddellii) or penguin (Pygoscelis adeliae) feces. However, isolation of E. coli from these vertebrates’ faeces was also low. Consequently, sewage disposal is introducing non-native microorganisms and associated resistance genes into the Antarctic environment. The impact of this “gene pollution” on the diversity and evolution of native Antarctic microbial communities is unknown.