ISS microbes must be monitored to avoid any threat to the health of astronauts

Strains of the bacteria Enterobacter, similar to the opportunistic infectious organisms recently discovered in a few hospitals, have been identified on the International Space Station (ISS). The strains found in space were not pathogenic for humans, but the researchers believe that it would be worth studying their potential health consequences for future missions, according to a report. study published in the journal open access. BMC Microbiology.

Researchers from the Jet Propulsion Laboratory at the California Institute of Technology in the United States have studied five strains of Enterobacter isolated from the space lavatories and the ISS exercise platform in March 2015 as part of a larger effort to characterize the bacterial communities living on the surfaces inside the space station. Identify species of Enterobacter collected on the ISS and to show in detail the genetic makeup of each strain, the researchers compared the ISS strains to all available genomes of 1,291 Enterobacter strains collected on Earth.

Dr Kasthuri Venkateswaran, senior scientist at the Global Protective Biotechnology and Planetary Protection Group of the Jet Propulsion Laboratory, said: "To show which species of the bacteria were present on the ISS, we used various methods to characterize their genomes We revealed that the genomes of the five ISS Enterobacter The strains were genetically the most similar to the three newly found strains on Earth. These three strains belonged to a species of the bacterium, Enterobacter bugandensis, known to cause disease in neonates and a compromised patient, who were admitted to three different hospitals (in East Africa, in the US). 39, Washington State and Colorado). "

The comparison of the genomes of the five ISS strains to the three clinical strains of the Earth allowed the authors to better understand whether the ISS strains had antimicrobial resistance characteristics, if their genetic profile was similar to that of known multidrug-resistant bacteria, and to identify genes related to their ability to cause disease (pathogenic potential).

Nitin Singh, first author of the publication, said: "Given the results of multidrug resistance E. bugandensis the genomes and the increased risks of pathogenicity that we have identified, these species pose potentially significant health problems for future missions. However, it is important to understand that the strains found on the ISS were not virulent, which means that they do not pose an active threat to human health, but need to be monitored. "

The authors found that ISS isolates had similar antimicrobial resistance profiles to those of the three clinical strains found on Earth and that they included 112 genes involved in virulence, disease, and defense. While the ISS E. bugandensis The authors predicted, by means of computer analyzes, that the strains were not pathogenic for humans, which represents a 79% probability that they could cause a disease. However, tests on living organisms must be performed to confirm this.

Dr. Venkateswaran said: "Whether it's an opportunistic pathogen or not, E. bugandensis causes a disease and its degree of threat depends on many factors, including environmental. 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. "

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More information:
Nitin K. Singh et al., Multiresistant Enterobacter bugandensis species, isolated from the International Space Station and comparative genomic analyzes on pathogenic strains for humans, BMC Microbiology (2018). DOI: 10.1186 / s12866-018-1325-2