Pollution by antibiotics and resistance genes: dissemination into Australian wildlife

The effects of antibiotic use and antibiotic resistance are now spreading beyond hospitals and human-dominated landscapes to encompass the whole biosphere. Antibiotics disseminated by waste streams pollute aquatic systems worldwide. These waste streams are also contaminated by bacteria that carry genes for resistance to antibiotics on mobile DNA elements. This circumstance means that aquatic ecosystems are now an evolutionary reactor for DNA rearrangements where novel genes can be assembled into ever more complex DNA elements, and then transferred into a growing diversity of bacterial species. As a consequence, bacteria containing antibiotic resistance genes have now been identified in a range of marine and terrestrial organisms, including wild species and species harvested for human consumption. The dissemination of these resistance genes will have unpredictable consequences for both native organisms and human welfare. Introduction Water bodies connect soils, oceans and the atmosphere, and provide essential ecosystem services, but are mostly no longer naturally regulated, since the water cycle has been fundamentally altered by human activity. Further deterioration of water quality is caused by sedimentation, salinisation, eutrophication and contamination with chemical and microbial pollutants (Meybeck 2003). Management of water sources in Australia faces unique challenges as it is the driest inhabited continent on Earth, and is subject to unpredictable variations in rainfall. Extraction of water for human activities is having serious ecological consequences in Australia (Kingsford 2000). Furthermore, water bodies are subject to both diffuse and point sources of pollution from industry, sewage and urban run-off (Francey et al. 2010).