A superbug is born on the International Space Station. It threatens astronauts and we don’t know what it will do when it reaches Earth – VTM.cz

Bacteria capable of causing serious diseases and at the same time resisting a wide range of antibiotics are the nightmare of modern medicine. They are constantly increasing. An illustrative example of the extreme resistance of microbes to antibiotics is offered by the causative agent of sexually transmitted gonorrhea, the bacterium Neisseria gonorrhoeae, which annually infects over 80 million people worldwide. It gradually acquired resistance to a wide range of drugs, and around 2020, one of the last hopes for treatment was the antibiotic ceftriaxone.

The American Centers for Diseases and Prevention states in a recently released report that even this antibiotic no longer works in 8% of cases in China and that the incidence of this “super gonorrhea” has tripled over the past five years.

Bacteria find ideal conditions for the development of resistance in hospitals, where many patients receive long-term treatment. In their weakened organism, bacteria thrive, even when exposed to antibiotics. In addition, such a “hospital” bacterium meets various antibiotics, so it undergoes direct serial selection for resistance.

But few would imagine the International Space Station as a breeding ground for antibiotic-resistant microbes. But that’s what the ISS really is. This was confirmed by a study by a team led by Kasthuri Venkateswaran from the Jet Propulsion Laboratory in Pasadena, USA, published in the scientific journal BMC Microbiology.

Thirteen Tribes

The scientists looked at the characteristics of the bacterium Enterobacter bugandensis based on more than two hundred completely read genomes. The microbes came from terrestrial conditions and from various locations on the International Space Station. According to a study by Venkateswaran et al., there are at least thirteen different strains of this bacterium on the station, with the finished hatchery being a bathroom with eight strains. Four strains occurred in the air and one on a weight machine in the gym.

During the last microbiological screening of the ISS station in 2018, scientists encountered four strains of the bacterium Enterobacter bugandensis. It is clear that the bacterium is thriving on the ISS and that it is using the space and conditions of the station to evolve greatly.

In earthly conditions, Enterobacter bugandensis is the cause of serious infections, especially in newborns, in which it causes inflammation of the heart muscle, urinary tract, skin and other soft tissues. The infection can turn into life-threatening sepsis, when bacteria overwhelm the entire circulatory system. Children with weakened immune systems are mostly infected. Unfortunately, the bacterium has already acquired resistance to some antibiotics, which complicates the treatment of infections.

Incubator of new bacteria

The International Space Station turns out to be an “incubator” of bacteria, but also fungi and other microorganisms that have traveled there during the quarter century of the station’s existence with almost three hundred astronauts. This is also clearly shown for the bacterium Enterobacter bugandensis. The latter have an average of 4568 genes on the ISS, while their terrestrial counterparts only have 4416, which represents a significant difference. Some genes were found by scientists only in Enterobacter bugandensis from the ISS, terrestrial strains lack them.

The conditions of the ISS, where there is microgravity, the air contains high concentrations of carbon dioxide and, last but not least, there is also a high level of radiation from sunlight, allow bacteria to evolve quite quickly through DNA mutations. Different types of bacteria interact there and hereditary information is exchanged between them through the so-called horizontal transfer, when bacteria of different types exchange genes with each other. Microorganisms form cooperative communities there, where the waste products of some are used by others as sources of nutrients. Each new astronaut brings with him new microbes that can take hold on the ISS.

On the ISS, Enterobacter bugandensis acquires not only resistance to station conditions, but also resistance to antibiotics. The evolutionary “mold” of this bacterium is certainly not over. The station performs particularly well in competition with other microbes and could become the dominant microorganism on the ISS.

It is not yet clear what effect the bacterium Enterobacter bugandensis has on the health of astronauts. However, scientists warn that the rapid development of microorganisms on the ISS may pose a risk to crews. In this context, we cannot forget the fact that the very stay on the space station is a heavy burden for the crew and that the immune system of the astronauts, for example, weakens. They are therefore more susceptible to infections than if they lived on Earth. But the idea that astronauts will bring more resistant “space” strains of Enterobacter bugandensis back to Earth and they will spread through the human population is not attractive either.