Bacteria are constantly being lifted to the stratosphere due to air movements caused by weather phenomena, volcanic eruptions, or human activity. In the upper parts of the atmosphere, they are exposed to extremely harsh and mutagenic conditions such as UV and space radiation or ozone. Most bacteria cannot withstand that stress, but for a fraction of them, it can act as a trigger for selective pressure and rapid evolution. We assessed the impact of stratospheric conditions on the survival and antibiotic resistance profile of common non-spore-forming human pathogenic bacteria, both sensitive and extremely dangerous multidrug-resistant variants, with plasmid-mediated mechanisms of resistance. Pseudomonas aeruginosa did not survive the exposure. In the case of strains that were recovered alive, the survival was extremely low: From 0.00001% of Klebsiella pneumoniae carrying the ndm-1 gene and methicillin-resistant Staphylococcus aureus mecA-positive with reduced susceptibility to vancomycin (MRSA/VISA), to a maximum of 0.001% of K. pneumoniae sensitive to all common antibiotics and S. aureus sensitive to vancomycin (MRSA/VSSA). We noticed a tendency towards increased antibiotic susceptibility after the stratospheric flight. Antimicrobial resistance is a current real, global, and increasing problem, and our results can inform current understandings of antibiotic resistance mechanisms and development in bacteria.

Astronauts and Cosmonauts who so far were carefully selected and both highly skilled and trained will no longer be the sole space fliers. In the advent of space tourism, implementation of methods allowing for fast and cost-effective medical evaluation and preparation for space flight is inevitable. In this document, we describe a simulator training, utilizing a programmable military human centrifuge (HC), allowing for both medical evaluation and acquaintance of future space tourism. The procedures and evaluation have been implemented and flight-tested on a programmable HC. It includes elements of hypergravity training and simulations of real-life rocket start and capsule atmosphere re-entry profiles. This training was implemented on three subjects with positive results and without impacting their health, performance, and wellbeing. Such training may become disruptive innovation that reduce costs of preparing space tourists for the real space flight.