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Pseudomonas aeruginosa is a dangerous bacterium that causes infections in hospitals and in people with weakened immune systems. It can cause bloodstream infections and pneumonia, while serious infections can be fatal. Very resistant to antibiotics, P. aeruginosa is one of the most critical pathogens urgently requiring alternative treatment strategies, according to the World Health Organization.
This bacterium is one of many organisms that have developed a system to acquire iron difficult to access the human body. Iron is essential for the growth and survival of bacteria, but in humans it is largely retained in the "hem" hemoglobin complex. To obtain it, P. aeruginosa and other bacteria secrete a protein, called HasA, which attaches to the heme in the blood. This complex is recognized by a membrane receptor on the bacterium called HasR, allowing the entry of heme into the bacterial cell, while HasA is recycled to extract more.
The bioinorganic chemist Osami Shoji of Nagoya University and his collaborators have found a way to divert this "heme acquisition system" for drug delivery. They developed a powder consisting of HasA and gallium phthalocyanine pigment (GaPc), which, applied to a culture of P. aeruginosa, was consumed by bacteria.
"When the pigment is exposed to near-infrared light, harmful reactive oxygen species are generated inside the bacterial cells," says Shoji. In tests, more than 99.99% of the bacteria were destroyed after treatment with a micromolar of HasA with GaPc and ten minutes of irradiation.
The strategy has also worked on other bacteria with the HasR receptor on their membranes, but not on those that are not.
The system of acquiring heme is so vital to the survival of these bacteria that it should not change, making it unlikely that the bacteria will develop resistance to this drug strategy, believe the researchers.
"Our findings support the use of artificial heme proteins as a Trojan horse to selectively provide antimicrobials to target bacteria, thus enabling their specific and effective sterilization, regardless of antibiotic resistance," reports Dr. 39, team in his study.
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Material provided by Nagoya University. Note: Content can be changed for style and length.
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