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Researchers have discovered a new antimicrobial coating that can thwart bacterial superbugs from growing in extreme spaceflight conditions, a finding that could aid future astronauts as they head to the moon, Mars and beyond.
Aboard the International Space Station (ISS), researchers tested a new silver and ruthenium-based antimicrobial coating dubbed AGXX and were able to decrease the amount of bacteria on contamination-prone surfaces.
Astronauts often face a number of obstacles as they travel through never explored regions of space, including microgravity, cosmic radiation, psychological stress and other conditions that can wreak havoc on their immune system. Coupling those conditions with increasingly strong bacteria puts anyone aboard ISS and other spaceships at risk of severe health issues.
“Spaceflight can turn harmless bacteria into potential pathogens,” senior study author Elisabeth Grohmann, a professor at Beuth University of Applied Sciences Berlin, said in a statement. “Just as stress hormones leave astronauts vulnerable to infection, the bacteria they carry become hardier developing thick protective coatings and resistance to antibiotics—and more vigorous, multiplying and metabolizing faster.”
The genes responsible for the new traits are shared amongst different bacterial species through direct contact, or in the matrix of slime they secrete, to create new forms of dangerous bacteria.
After testing the new antimicrobial coating on the contamination-prone toilet door aboard ISS, the researchers are hopeful they can combat the growing army of superbugs.
“AGXX contains both silver and ruthenium, conditioned by a vitamin derivative, and it kills all kinds of bacteria as well as certain fungi, yeasts and viruses,” Grohmann said. “The effects are similar to bleach – except the coating is self-regenerating so it never gets used up. After six months exposure on the ISS, no bacteria were recovered from AGXX-coated surfaces.”
After finding 112 bacterial isolates after three months of using AGXX, the researchers recovered just 12 different bacteria isolates after both 12 and 19 months, a reduction of 80 percent compared to bare steel. They also tested a regular silver coating, which has long been known for prevent microbial growth, which reduced the number of bacteria by only 30 percent versus steel.
“With prolonged exposure time a few bacteria escaped the antimicrobial action,” Grohmann said. “The antimicrobial test-materials are static surfaces, where dead cells, dust particles and cell debris can accumulate over time and interfere with the direct contact between the antimicrobial surface and the bacteria.
“Most importantly, no serious human pathogens were found on any surface,” she added. “Thus, the infection risk for the ISS crew currently is low.”
They also found that all the bacteria isolate were able to form immunity-evading slimy coatings, making them resistant to at least three different antibiotics, while able to share the genes responsible.
“Immunosuppression, bacterial virulence and therefore infection risk increase with duration of spaceflight,” Grohmann said. “We must continue to develop new approaches to combat bacterial infections if we are to attempt longer missions to Mars and beyond. For our part, we are continuing to analyze the antimicrobial performance of AGXX, most recently aboard the joint IBMP-NASA SIRIUS 18/9 isolation mission.”
The study was published in Frontiers in Microbiology.
