The Interplay of Low and High LET Radiation to Antibiotic Resistance in Deep Space

Antibiotic resistance presents a grave concern for astronauts embarking on deep space missions, like those going to Mars, due to the extended mission durations and the isolated, confined environment that increase the risk of infectious diseases. During such missions, resupplying antibiotics from Earth or producing them on board can be challenging if a bacterial infection arises. The space environment primarily consists of low linear energy transfer (LET) radiation, predominantly protons from galactic cosmic rays (GCR) and solar particle events (SPE). Although heavy ions, contributing a small fraction of total radiation exposure, possess a large potential to harm biological tissue due to their high LET and penetration capabilities, their role in inducing antibiotic resistance remains poorly understood. Assessing the impact of high LET heavy ions on antibiotic resistance, particularly following low-LET radiation exposure, is vital for space missions and for medical settings. In this paper, three potential scenarios are examined: synergism, where combined factors significantly enhance antibiotic resistance; simple addition, where effects are cumulative but not highly intertwined; and antagonism, where the combined exposure weakens antibiotic susceptibility. In summary, antibiotic-resistant bacteria during long-term space missions pose a substantial threat to crew health, mission success, and financial investments. Thus, developing effective infection control strategies and alternative antimicrobial therapies are paramount to mitigate antibiotic resistance risks in deep space missions. Further research is imperative to inform medical and space exploration protocols.