by Becky Ferreira
The International Space Station.
strains of bacteria
in the ISS
toilets, but say they pose
no threat to the
Drug-resistant bacteria - germs that have adapted immunities to
antibiotic treatments - have found their way to the International
Space Station, according to a new study.
Led by Nitin Singh, a microbiologist at NASA's Jet Propulsion
Laboratory, the study (Multi-drug
resistant Enterobacter bugandensis Species Isolated from the
International Space Station...),
published in BMC Microbiology, examined five strains of
Enterobacter bacteria from samples collected in 2015 from the
toilets and exercise equipment onboard the ISS.
Enterobacter is a common and mostly harmless bacterial family, but
drug-resistant strains of the organism have been flagged in
hospitals. A 2015 outbreak in a Tanzanian neonatal unit, for
instance, caused blood infections in newborn babies.
Singh and his colleagues wanted to assess the virulence of the
Enterobacter strains on the ISS
compared to antimicrobial-resistant pathogens on Earth.
To do this, the team
mapped the genomes of the space strains and compared them to the
roughly 1,300 known Enterobacter genomes.
Their analysis revealed that the five strains were most genetically
similar to Enterobacter bugandensis, the same drug-resistant
species responsible for the Tanzania outbreak.
The finding corroborates a Nature paper (Detection
of antimicrobial resistance genes associated with the International
Space Station environmental surfaces) from January that
suggested E. bugandensis might be present on the space station.
Singh's team expanded
beyond that research by evaluating the genetic virulence of the
strains and their potential to infect the astronauts.
The upshot is that these space bugs do not pose any immediate threat
to ISS crews because they are genetically distinct from the most
infectious forms of E. bugandensis.
But there is enough
the ISS germs and their pathogenic
Earth cousins to warrant careful attention to
the microbiome going forward.
potentially pose important health considerations for future
missions," Singh said in a statement.
"However, it is
important to understand that the strains found on the ISS were
not virulent, which means they are not an active threat to human
health, but something to be monitored."
Bacterial strains can
adapt rapidly to new habitats, so the relatively benign bugs on the
ISS today may not be harmless forever.
It's difficult to keep
pace with drug-resistant bacteria, so the CDC suggests focusing on
preventative measures, like isolating infected patients and paying
careful attention to antibiotic prescriptions.
Of course, such guidelines are a lot more difficult to impose on
patients living 220 miles above Earth, which is why ISS researchers
will have to keep close tabs on the station's bacterial community.