Enterococcus faecium changes in antibiotic resistance, biofilm formation and desiccation tolerance after exposure to simulated microgravity

Kurzfassung

Vancomycin-resistant Enterococcus faecium (VRE) presents a substantial healthcare challenge, notably for hospitalized patients and immunocompromised individuals, including astronauts whose immune systems are compromised during spaceflight. This raises concerns about VRE's adaptability under conditions of altered gravity. We conducted a comprehensive screening of 42 clinical E. faecium isolates after incubation in simulated microgravity (sim. µg) using a 2-D Clinostat with standard gravity conditions (1 g) as control. The isolates, including vancomycin-susceptible (VSE), vancomycin-resistant (VRE), and vancomycin-variable (VVE-B) strains, were tested against a panel of 22 antibiotics after 7 days of incubation in sim. µg and 1 g. Additionally, all isolates were characterized for their biofilm formation and tolerance to desiccation under these conditions. Our findings revealed variable responses in minimum inhibitory concentration (MIC) values for seven different antibiotics. Notably, 55 % (23/42) of the isolates demonstrated a trend of enhanced biofilm production, and 59 % (25/42) showed improved desiccation tolerance after exposure to sim. µg. Overall, our findings indicate that E. faecium can adapt their antibiotic susceptibility, alter their desiccation tolerance and show increased biofilm formation under sim. µg. This investigation offers first insights of E. faecium's dynamic adaptability in response to simulated spaceflight conditions, highlighting significant changes in antibiotic resistance, biofilm formation, and desiccation tolerance. The variability and adaptability observed underscore the importance of further understanding VRE's resilience to microgravity.