Urinary tract infections steal from hosts' defense arsenals

Jul 08, 2012
An immune cell known as a neutrophil (shown in light blue) attacks bacteria infecting the lining of the bladder. Scientists at Washington University School of Medicine have learned that the bacteria that cause urinary tract infections can steal copper -- a potent microbicide -- to prevent the copper from being used against them. Credit: Chia Hung, Ph.D.

Humans have known for centuries that copper is a potent weapon against infection. New research shows that the bacteria that cause serious urinary tract infections "know" this, too, and steal copper to prevent the metal from being used against them.

Blocking this thievery with a drug may significantly improve patients' chances of fighting off infections, according to researchers at Washington University School of Medicine in St. Louis. The findings appear online July 8 in Nature .

In the United States alone, annual treatment costs for urinary tract infections are estimated to run as high as $1.6 billion. Most urinary tract infections are caused by (E. coli).

"While some patients are able to clear these infections without issue, in others the infection persists or recurs despite ," says senior author Jeff Henderson, MD, PhD, assistant professor of medicine and of . "In some cases, the infection spreads to the kidney or the blood and becomes life-threatening. We've been investigating what's different about the bacteria that cause these more troublesome infections."

Scientists have known for years that E. coli makes a molecule called yersiniabactin that takes iron from host cells. The bacteria need the iron to grow and reproduce.

An immune cell known as a neutrophil (shown in light blue) attacks bacteria infecting the lining of the bladder. Scientists at Washington University School of Medicine have learned that the bacteria that cause urinary tract infections can steal copper -- a potent microbicide -- to prevent the copper from being used against them. Credit: Chia Hung, Ph.D.

In earlier research, Henderson found that the E. coli that cause serious infections are more likely to make yersiniabactin. This finding and the fact that E. coli already produce another molecule that steals iron led Henderson and Kaveri Chaturvedi, a student in his laboratory, to suspect that the might be using yersiniabactin for other purposes.

To test the theory, the researchers put yersiniabactin in from healthy patients. They found the molecule bound iron as expected but also picked up copper. Next, they conducted the same analysis in samples from patients with urinary tract infections who were treated at the University of Washington in Seattle.

"We found copper bound to yersiniabactin in nearly every patient whose bacteria made the molecule," Henderson says. "Yersiniabactin was often bound to copper more than it was to iron."

When researchers put E. coli in the same test tube with copper, the bacteria that made yersiniabactin were more likely to survive.

Copper's microbe-fighting properties were recognized long before scientists had described the microbes that cause infection. Ancient Greeks and Egyptians knew that treating wounds with copper improved the healing process.

Modern researchers have two explanations for copper's anti-microbial effects: the metal can stimulate production of other chemically reactive that damage bacteria; and it is also directly toxic to the bacteria.

Henderson, who treats patients with urinary tract infections at Barnes-Jewish Hospital, is currently studying whether the presence or absence of yersiniabactin can help physicians assess an infection's chances of becoming more serious.

He and his colleagues are also looking at other disease-causing bacteria that make yersiniabactin to see if they use it in a fashion similar to the E. coli that cause .

Explore further: Expanding the code of life with new 'letters'

Related Stories

Urinary tract infections linked to contaminated chicken

Feb 20, 2012

Urinary tract infections are common conditions that occur when bacteria from the intestines enter the urinary tract. New research, however, suggests that the bacteria causing these infections may come from contaminated food ...

New strategy to combat cystitis

Jun 03, 2011

One in three women will be faced at least once in her life with cystitis, for some the start of a constantly recurring infection. Cystitis is caused by Escherichia coli bacteria which fasten on to the wall of the bladder by mea ...

Recommended for you

Expanding the code of life with new 'letters'

1 hour ago

The DNA encoding all life on Earth is made of four building blocks called nucleotides, commonly known as "letters," that line up in pairs and twist into a double helix. Now, two groups of scientists are reporting ...

Researchers find 'decoder ring' powers in micro RNA

May 26, 2015

MicroRNA can serve as a "decoder ring" for understanding complex biological processes, a team of New York University chemists has found. Their study, which appears in Proceedings of the National Academy of Sciences, points ...

DNA mutations get harder to hide

May 26, 2015

Rice University researchers have developed a method to detect rare DNA mutations with an approach hundreds of times more powerful than current methods.

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

sennekuyl
not rated yet Jul 09, 2012
Is there a reason the Solar Cloth is used for the main image of urinary tract infections?
http://phys.org/n...ble.html
antialias_physorg
not rated yet Jul 09, 2012
Good catch. It seems that what they wanted to show in that place is the image further down in the article (as the captions are identical)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.