Drug-Resistant Bacteria Found on International Space Station Toilet

The bacteria do not currently pose a risk to astronauts, but that could change as the microbes adapt to their environment


Health officials have for some time been worried about “superbugs,” or microorganisms—like bacteria, viruses and parasites—that develop resistance to medications, rendering them difficult to treat. And superbugs may not only be a problem here on Earth. According to Chase Purdy of Quartz, a new study of bacteria on board the International Space Station found five strains with characteristics of drug resistance.

As part of an ongoing effort to learn more about the microbes that astronauts are exposed to while in orbit, researchers at NASA’s Jet Propulsion Laboratory (JPL) analyzed 105 bacterial strains sampled from various spots around the International Space Station (ISS) in 2015. Five of these bacteria were found to be strains of Enterobacter, which is known to cause a variety of infections in humans. Enterobacter strains have also developed resistance to multiple drugs.

The new study, published in the journal BMC Microbiology, took a closer look at the five ISS strains. One had been collected from an exercise device, while the other four came from the “waste and hygiene compartment,” or the toilet, in other words.

Researchers used “various methods to characterize their genomes in detail,” says Kasthuri Venkateswaran, study co-author and a senior research scientist at the NASA JPL. The team also compared the ISS bacteria to 1,291 Enterobacter strains collected on Earth. The ISS strains were found to be most similar to three strains of bacteria that had recently been identified as the cause of disease in newborns and a “compromised patient” in three different hospitals: one in Africa, one in Washington state and one in Colorado. The hospital strains belonged to a single species of bacteria called Enterobacter bugandensis.

The researchers discovered that the ISS isolates had similar antimicrobial resistance patterns to the Enterobacter bugandensis strains from Earth. It’s important to note that the strains were not found to be virulent, meaning that they do not currently pose any threat to astronauts on board the Space Station. But the new research revealed that the ISS isolates had 112 genes related to “virulence, disease, and defense,” the study authors write. Using computer analyses, the authors predicted that the ISS strains have a 79 percent probability of becoming pathogenic to humans.

Lead study author Nitin Singh tells Chelsea Gohd of Discover there is some concern that as the bacteria adapt to their new environment, astronauts will be susceptible to infection because the immune system goes a bit wonky in space.

“Once the immune system starts to weaken, microbes which were previously harmless could make you sick,” Singh explains.

Granted, scientists don’t yet fully understand how pathogens like Enterobacter bugandensis behave in the unique space environment. Researchers would need to study the ISS bacterial strains in a living body to get a better sense of how they might impact astronauts working on the Space Station. So the bacteria are, as Singh puts it, “something to monitored” to ensure that our astronauts stay healthy and safe.

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