LOS ANGELES, March 17 (Xinhua) -- The Trojan horse strategy has been successfully applied to defeat drug-resistant bacteria, according to a new study.

    This new antimicrobial approach can kill bacteria in laboratory experiments and eliminate life-threatening infections in mice by interfering with a key bacterial nutrient, according to the study by scientists at the University of Washington (UW), the University of Iowa and the University of Cincinnati.

    This is the result of longtime efforts by scientists to find new antibiotic compounds as bacteria are increasingly resistant to antibiotics, and existing drugs work poorly against chronic infections like those that occur in wounds, on medical devices andin the lungs of people with cystic fibrosis.

    In this study, researchers took a different approach. Rather than trying to find agents that best killed bacteria in test tubes, they sought to intensify the stress imposed on microbes by one of the body's own defense mechanisms.

    "The competition for iron is critical in the struggle between bacteria and host," explained the study's senior author, Pradeep Singh, associate professor of medicine and microbiology at the UW."The body has potent defense mechanisms to keep iron away from infecting organisms, and invaders must steal some if they are to survive."

    Iron is critical for the growth of bacteria and for their ability to form biofilms, slime-encased colonies of microbes that cause many chronic infections.

    "Because iron is so important in infection, we thought infecting bacteria might be vulnerable to interventions that target iron," explained Yukihiro Kaneko, senior fellow in microbiology at the UW and the study's lead author.

    To accomplish this, the researchers used gallium, a metal very similar to iron.

    "Gallium acts as a Trojan horse to iron-seeking bacteria," said Singh. "Because gallium looks like iron, invading bacteria are tricked, in a way, into taking it up. Unfortunately for the bacteria, gallium can't function like iron once it's inside bacterial cells."

    The study showed that gallium killed microbes, and prevented the formation of biofilms. Importantly, gallium's action was intensified in low iron condition, like those that exist in the human body.

    Gallium was even effective against strains of Pseudomonas aeruginosa from cystic fibrosis patients that were resistant to multiple antibiotics.

    In mice, gallium treatment blocked both chronic and acute infections caused by this bacterium.

    The joint study will be featured in the April 2 issue of the Journal of Clinical Investigation.