Bacterial resistance to copper in the making for thousands of years

Since humans use copper to fend off bacteria, I would guess that other animals also do so, so we are endangering not only our own species.

http://www.eurekalert.org/pub_releases/2016-03/osu-brt031616.php

PUBLIC RELEASE: 16-MAR-2016
Bacterial resistance to copper in the making for thousands of years
Genetic changes pose risks to human immunity
OHIO STATE UNIVERSITY

Human use of copper dating back to the Bronze Age has shaped the evolution of bacteria, leading to bugs that are highly resistant to the metal's antibacterial properties.

Large amounts of copper are toxic to people and to most living cells. But our immune systems use some copper to fend off bacteria that could make us sick.

More copper in the environment leads to more bacteria, including E. coli, that develop a genetic resistance. And that could pose an increased infection risk for people, said Jason Slot, who directed a new copper-resistance study and is assistant professor of plant pathology at The Ohio State University.

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Slot and his colleagues created a molecular clock, using bacterial samples collected over time and evolutionary analysis to trace the history of copper resistance. The team studied changes in bacteria and compared those to human use of copper. Their work suggests there were repeated episodes of genetic diversification within bacteria that appear to correspond to peaks in copper production.

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Today, copper is widely used in industry, including in farming, where the metal is added to feed to fatten up animals. And in recent years, there's been a movement toward using copper more in medical settings because of its antibacterial properties, Slot said.

"You're enticing the bacteria in the environment to develop a mechanism that evades your immune system," Slot said.

"I think overuse of anything is a bad idea, but it's really hard for people not to overuse the few weapons that we have."