Genomic Enumeration of Antibiotic Resistance in Space (GEARS)

Science Objectives

Many antibiotics commonly used to treat bacterial infections no longer work because the target bacteria have evolved defenses against these medicines. Two common bacteria, Enterococcus faecalis (EF) and Enterococcus faecium, previously have been isolated on the International Space Station and show antibiotic resistance and tolerance to desiccation, starvation, and disinfection. This makes them potent pathogens in this type of built environment. CS-05A: Genomic Enumeration of Antibiotic Resistance in Space (GEARS) surveys the space station for antibiotic resistant-organisms, including EF. Genetic analysis could show how these bacteria adapt to the space environment, providing knowledge that informs measures to protect astronauts on future long-duration missions.


Experiment will launch to the International Space Station (ISS) on the SpaceX-30 Commercial Resupply Service mission in March, 2024.

Experiment Description

Enterococci are gram-positive bacteria that originated when ancient ancestors to current animals emerged from the oceans to live on land and brought their gut flora with them. Enterococcus faecalis (EF) and Enterococcus faecium, are common human commensals and can harbor multidrug resistance. Both have been previously isolated on the International Space Station. Likely as a consequence of their evolutionary origins, enterococci show remarkable stress resistance within, but also outside, their human hosts. Their antibiotic resistance, coupled with tolerance to desiccation, starvation, and disinfection, make some EF strains potent pathogens in the built environment (e.g., hospitals), and a potential risk to crew health during space missions.

Space Applications

Studies have shown that spaceflight can weaken the human immune system. The possible presence of antibiotic-resistant bacteria on the space station increases the risk of infection in crew members. Monitoring and characterizing the type and frequency of antibiotic-resistant organisms and understanding how they evolve in microgravity provides knowledge that can help reduce that risk. The on-orbit sequencing used for this research also could advance development of point-of-care diagnostic capabilities for future missions.

Earth Applications

Antibiotic resistance is a growing threat to human health on Earth, resulting in 2.8 million infections and 35,000 deaths annually. Bacteria evolve in response to the over-use of antibiotics, with Staphyloccoci and Enterococci the first and second leading causes of hospital-acquired infections. The space station is a built environment similar in some ways to hospitals, and studying antibiotic-resistant microbes there could provide insight into how these organisms survive, adapt, and evolve in response to their environment, helping to protect the health of people on Earth.

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