The researchers analyzed samples collected from the toilet and exercise platform aboard the ISS in March 2015. Once the bacteria were identified, they compared the outer space strains to the genomes of the nearly 1,300 Enterobacter strains sequenced on Earth.

The study revealed that the ISS strains were not harmful to humans but shared characteristics with antimicrobial resistant pathogenic bacteria on Earth.

“The microbial strains that were found in our study were not virulent, meaning none poses a threat to human health,” Singh said. “But this study highlights why it’s essential to monitor the microbiome of the ISS. Keeping an eye on how microbes grow and adapt, lets us take better care of astronaut health, and could teach us how to be more efficient on where and how frequently to clean different parts of the station.”