Multi-resistant biofilm-forming pathogens on the International Space Station

The International Space Station (ISS) is a confined and closed habitat with unique conditions such as cosmic radiation, and microgravity. These conditions have a strong effect on the human and spacecraft microflora. They can affect the immune response of the crew-members, thus posing a threat to their health. Microbial diversity and abundance of microorganisms from surfaces, air filters and air samples on the ISS have been studied. Enterobacteriaceae, Bacillus spp., Propionibacterium spp., Corynebacterium spp., and Staphylococcus spp. were among the most frequently isolated bacteria. Microbial growth, biofilm formation, stress response, and pathogenicity are affected by microgravity. Increased resistance to antibiotics in bacteria isolated from the ISS has often been reported. Enterococcus faecalis and Staphylococcus spp. isolates from the ISS have been shown to harbor plasmid-encoded transfer genes. These genes facilitate the dissemination of antibiotic resistances. These features of ISS-pathogens call for novel approaches including highly effective antimicrobials which can be easily used on the ISS. A promising material is the antimicrobial surface coating AGXX, a self-recycling material consisting of two noble metals. It drastically reduced microbial growth of multi-resistant human pathogens, such as staphylococci and enterococci. Further novel approaches include the application of cold atmospheric plasma for the sterilization of spacecrafts.