'Space superbugs could threaten astronauts'

Astronauts are at an increased risk of infections in space as weightlessness of outer cosmos can make germs even nastier, researchers say. In space, astronauts encounter greatly reduced levels of gravity, often erroneously referred to as zero gravity. This near-weightlessness can have a number of abnormal effects on astronauts, such as causing muscle and bone loss. "We seek to unveil novel cellular and molecular mechanisms related to infectious disease progression that cannot be observed here on Earth, and to translate our findings to novel strategies for treatment and prevention," said microbiologist Cheryl Nickerson at Arizona State University's Biodesign Institute. Although microgravity can distort normal biology, conventional procedures for studying microbes on Earth can cause their own distortions, SPACE.com reported. Experiments on Earth often involve whirling cells around to keep them from settling downward in a clump due to gravity. The most common sites of human infection are the mucosal, gastrointestinal and urogenital tracts, where fluid shear is typically low. In an earlier series of NASA space shuttle and ground-based experiments, Nickerson and her colleagues discovered that spaceflight actually boosted the virulence, or disease-causing potential, of the food-borne germ Salmonella. "Does microgravity alter how Salmonella behaves? You bet it does, in a profound and novel way," Nickerson said. This aggressive bacterium infects an estimated 94 million people globally and causes 155,000 deaths each year. "By studying the effect of spaceflight on the disease-causing potential of major pathogens like Salmonella, we may be able to provide insight into infectious disease mechanisms that cannot be attained using traditional experimental approaches on Earth, where gravity can mask key cellular responses," Nickerson said. These findings are of special concern for astronaut health during extended spaceflight missions. Space travel already weakens astronaut immunity, and these findings reveal that astronauts may have to further deal with the threat of disease-causing microbes that have boosted infectious abilities.