Rivers of Gene Flow

Abstract

Ecology![Figure][1] CREDIT: © PETE MCBRIDE/NATIONAL GEOGRAPHIC SOCIETY/CORBIS Antibiotic resistance is becoming an urgent problem. We point one finger at lax medication sales, and another at livestock husbandry, but there is also an ancient background signal of antibiotic resistance, in part stemming from the natural functions of these molecules in the soil. Even if we control the clinical use of antibiotics, there is still a growing problem of resistance. Where is it coming from? Pruden et al. have made the enormous undertaking of identifying environmental sources of antibiotic resistance genes in one river system from pristine sources in the Rocky Mountains, flowing through not just an altitudinal gradient but also a gradient of human activity. The background signal was measured by the occurrence of the tet(W) (tetracycline resistance) gene, whereas the sul1 (sulphonamide resistance) gene was taken as a marker of anthropogenic contamination. The results unambiguously showed accumulation of the sul1 gene down the river basin, primarily contributed by upstream animal feeding operations, with a modest input from wastewater treatment. Environ. Sci. Technol. 46 , 11541 (2012). [1]: pending:yes