http://www.digitaljournal.com/science/wastewater-may-not-trigger-antibiotic-resistance/article/446183

Wastewater may not trigger antibiotic resistance

Posted Oct 10, 2015 by Tim Sandle
Some scientists have been concerned that wastewater, where bacteria and antibiotics mix, could be seeding an increase in antibiotic resistance. A new study puts forward evidence that this is not the case.
Discharge pipe: The new study documents the finding of ammonium  iodide and artificial sweeteners at...
Discharge pipe: The new study documents the finding of ammonium, iodide and artificial sweeteners at high levels flowing into our rivers and streams.
US Department of Agriculture
In June 2015, Digital Journal reported about the presence of large numbers of antibiotics in wastewater. In research led by Professor Olya Keen, of UNC Charlotte it was argued that treatments to "clean up" wastewater could modify antibiotics and trigger an increase in antibiotic resistant bacteria.
Scientists based at Aalborg University, Technical University of Denmark have taken a different position. The researchers have studied the genes, collected from wastewater treatment plants, that aid bacteria in developing antimicrobial resistance. Wastewater contains a mix of antimicrobial agents, discarded by people at home, pharmaceutical companies and hospitals, along with a variety of pathogenic bacteria. Many of these bacteria are — unsurprisingly given where much of the water comes from — found in the intestines of people.
The new findings show that treatment plants contain many genes that can potentially trigger resistance to a range of antimicrobial agents. While this poses a potential risk, studies indicate that these genes are only very rarely found in bacteria outside the wastewater treatment plants. This would suggest that water treatment plants are not a mechanism for passing on resistance genes to bacteria.
To verify the findings the researchers looked at five wastewater treatment plants in Denmark and took hundreds of samples. The samples were collected over a two year period.
The new research has been reported to the journal Nature Communications. The paper is titled “Limited dissemination of the wastewater treatment plant core resistome.”