Antibiotic-resistant bacteria found on the ISS – it has been around for at least two years

The International Space Station may seem sober, but it is teeming with germs. JPL-NASA scientists reported identifying several strains of Enterobacter in samples taken from the toilets and exercise areas of the space station. Enterobacter is best known for having infected patients whose immune systems are weakened in hospitals and extremely resistant to antibiotics.

SpaceBugs

Fortunately, the strains identified on the ISS are not pathogenic for humans (they do not infect). And while it's virtually impossible to have humans without bacteria – we're dragging our own microbiomes wherever we go – the mere fact of finding any Enterobacter strain on the station is disturbing enough.

The genre is infamous for its prey on immunocompromised patients here on Earth; He is also known for his ridiculous resistance to antibiotics. The space is (forgive the beast) an environment out of this world. There is more radiation, there is almost no gravity, there are humans everywhere, piled in a tube containing a lot of carbon dioxide. All these constraints could change the lifestyle and multiplication of microbes – these changes could, in turn, make them pathogenic for humans.

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NASA employs a handful of microbiologists in its jet propulsion lab, who regularly analyze specimens of microbes sent from the ISS to determine if life in the space is changing their populations or habits. Microbiologists also monitor any potential biological risk to astronaut equipment or health. This is the first time they have identified antibiotic-resistant Enterobacter strains in the station.

"To show what species of bacteria were present on the ISS, we used various methods to characterize their genomes in detail. We revealed that the genomes of the five ISS strains of Enterobacter were genetically more similar to the three newly discovered strains on Earth, "explained microbiologist Kasthuri Venkateswaran.

"These three strains belonged to a species of the bacteria called Enterobacter bugandensis, who had been found to cause illness in neonates and a compromised patient, who were admitted to three different hospitals (in East Africa, Washington State, and Colorado). "

Samples were collected in 2015. Since no astronaut has been struck since, insects do not appear to pose an immediate threat. However, the team believes that this state of affairs can quickly change – and that it would be serious. The Enterobacter of spatial origin were resistant to a wide range of antibiotics and virtually completely immune to cefazolin, cefoxitin, oxacillin, penicillin and rifampin.

Enterobacter cloacae.
Image Credit CDC Public Health Image Library (PHIL # 6552).

The strains also share 112 genes with clinical strains, associated with virulence, disease and defense. The team reports that computer models show a 79% probability that spatial strains develop a human pathogen and cause disease.

At the present time, however, astronauts are safe. The possibilities, as worrying as they are, remain to be tested in living organisms. The team is therefore trying to better understand the situation and develop a response procedure (which she hopes to never use) against this bacteria.

"Whether or not an opportunistic pathogen such as E. bugandensis is a cause of the disease depends on many factors, including environmental ones," Venkateswaran said. "Other in vivo studies are needed to determine the impact that conditions on the ISS, such as microgravity, other factors related to space and spacecraft. , can have on pathogenicity and virulence. "

The document "Multi-resistant species of Enterobacter bugandensis, isolated from the International Space Station and comparative genomic analyzes with pathogenic strains for humans" was published in the journal BMC Microbiology.

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