Iron plays important role in formation
of drug-resistant bacteria
Understanding the role iron plays in the formation of bacterial infections
could shed more light on drug-resistant strains and give doctors new hope
of improving the health of patients suffering from cystic fibrosis and other
debilitating diseases, according to a recent report in a leading scientific
journal.
Researchers from the University of Colorado Denver and the University of Washington-Seattle made an important connection
between disease-causing bacteria and their ability to use certain forms of
iron to form complex communities that are highly resistant to antimicrobial
drugs. The communities, called biofilms, also resist the body’s defenses
against infections.
“There is a very delicate and integrate balance between the host and the
infectious agent with regard to the availability of iron,” said Michael
Vasil, PhD, professor of microbiology at UCD and co-author of the study. “If
the organism is able to out-compete the host for available iron or destroy
its ability to withhold iron, then it is much more likely to cause a serious
infection.”
The findings of the study, published in the July 18-22 edition of Proceedings
of the National Academy of Sciences of the United States, could result in
better antibiotics and increased awareness of how iron in the diet might
affect people battling certain illnesses.
In particular, researchers are hopeful their findings will lead to new treatments
for people living with cystic fibrosis, a genetic disease that causes the
body to produce abnormally thick mucus that clogs the lungs and leads to
life-threatening infections. The thick substance contains biofilms produced
by the most prevalent bacterial infectious agent in patients with cystic
fibrosis, Pseudomonas aeruginosa, Dr. Vasil said.
About 30,000 Americans are living with cystic fibrosis, and another 10 million
are unknowing carriers, according to the Cystic Fibrosis Foundation.
According to the study, predatory, iron-loving infectious agents such as
Pseudomonas aeruginosa require certain kinds of iron to be able to form biofilms.
During an infection, bacteria obtain this iron by effectively overcoming
the host’s ability to withhold it.
In most healthy people, the body can keep iron away from an infectious agent
by producing proteins such as lactoferrin and storing excess iron in certain
organs such as the liver.
However, Pseudomonas aeruginosa and similar bacteria
are better at producing strong iron-binding compounds called siderophores,
or iron lovers, and are more likely to infect a susceptible host by interfering
with the function of proteins such as lactoferrin. These bacteria can steal
iron from the host by either making siderophores that bind iron more effectively
than the host’s proteins or by actually degrading the host’s
iron-binding proteins and using the released iron to make biofilms.
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