Copper Fuels Dual-Edged Resistance: A New Threat Emerges

Study Reveals How Copper’s Antimicrobial Power Can Foster Antibiotic-Proof Bacteria

While copper has long been a trusted agent against microbial threats, new research from UCLA highlights a critical downside: its overuse can inadvertently cultivate bacteria resistant not only to copper but also to vital antibiotics.

The Copper-Antibiotic Link

Scientists at UCLA have uncovered a concerning connection between the widespread application of copper-based antimicrobials and the rise of antibiotic-resistant bacteria. Their findings, published in *Evolution, Medicine and Public Health*, indicate that environments heavily exposed to copper, such as agricultural settings utilizing copper sulfate for pest control, can exert evolutionary pressure on bacteria.

This pressure can lead to the development of resistance mechanisms in bacteria that simultaneously confer immunity to antibiotics.

“We found that bacteria that evolve resistance to copper also become resistant to antibiotics, possibly because they are using biological pathways that help them resist copper to also resist antibiotics.”

—Sada Boyd-Vorsah, first author and UCLA postdoctoral researcher

Antibiotic resistance, a growing global health crisis, arises when bacteria evolve traits that enable them to survive treatments designed to kill them. This natural selection process means that any substance posing a threat to microbial life, including metals like copper, can inadvertently drive this dangerous evolution.

Unpacking the Research Methodology

The research team exposed populations of *E. coli* bacteria to copper sulfate in laboratory settings. After several generations, the surviving bacteria demonstrated significant resistance to copper. Subsequent testing revealed these copper-hardened microbes also exhibited heightened resistance to various common antibiotics.

Genetic analysis identified 477 mutations in the copper-resistant bacteria. While some mutations directly targeted metal resistance, others affected pathways that bacteria utilize to cope with diverse environmental stressors, reinforcing the idea that resistance to one agent can spill over to others.

A striking discovery was the rapid decline in resistance. After just seven days without copper exposure, bacterial resistance levels dropped significantly, though variability between different bacterial populations was observed.

Strategic Use for a Sustainable Solution

The implications of this research are significant for public health and agriculture. While copper remains a potent antimicrobial, its application requires careful consideration to avoid exacerbating the antibiotic resistance crisis. Alternating copper-based treatments with other antimicrobial strategies may offer a way to leverage copper’s benefits without promoting widespread resistance.

Pamela Yeh, a UCLA professor and corresponding author, emphasized the potential for this phenomenon to be widespread.

“I don’t see any reason why we wouldn’t expect that this is probably a generalizable pattern that could be found across many, maybe even all, species of bacteria because the mechanisms that confer resistance are probably evolutionarily very ancient.”

—Pamela Yeh, UCLA professor of ecology and evolutionary biology

Globally, antimicrobial resistance is estimated to cause approximately 1.27 million deaths annually, with projections suggesting it could rise to 10 million deaths per year by 2050 if current trends continue (World Health Organization, 2023).

The findings suggest that a nuanced approach to antimicrobial use, carefully balancing the benefits of agents like copper with strategies to prevent resistance, is crucial for safeguarding human and animal health.