LAUSR

Despite their elevated risk for morbidity and mortality from infections, the microbiota of older adults remain understudied. While colonization resistance from resident microflora is a promising means to prevent infections, little is known about pathogenicity reservoirs and colonization resistance in this vulnerable population. Here we study the skin, oral, and gut microbiome dynamics of older adults in both community and Skilled Nursing Facility (SNF) settings, investigating relationships between age, frailty, environment, microbiota, and pathogenicity reservoirs. We conducted a longitudinal metagenome survey of 47 adults age 65+ years of age; 22 residents of 3 different SNFs and 25 community dwelling individuals. We performed metagenomic whole genome shotgun sequencing on stool, oral, and skin samples from 8 sites, 1421 total. To correlate clinical and behavioral variables, we measured frailty, collected medical records, and interviewed participants on diet and lifestyle. We also draw comparisons with previous younger cohorts. • Compared to younger adults, the skin microbiota of older adults was characterized by ◦ High heterogeneity ◦ Decreased stability over time, suggesting increased susceptibility to colonization and pathogenicity ◦ Compositional differences including significantly lower levels of Cutibacterium acnes, with reciprocal increases in Staphylococci, Corynebacteria, and Malassezia • In older adults, Frailty (Rockwood) was found to have linear correlation with relative abundance of species relevant to infection risk including acnes, staphylococci, streptococci, E. coli, Akkermansia mucinophila, and Enterococcus faecalis. • The skin, oral, and gut microbiota of SNF residents had substantially elevated virulence factor and antibiotic resistance genes. To the best of our knowledge, this is largest report to date of the skin metagenome in older adults. We demonstrate distinct and significant differences between cohorts with clinically relevant implications. We believe these results may inform infection control and prevention by increasing our understanding of colonization resistance and pathogenicity reservoirs, as well as advance our knowledge of the relationship between aging, the microbiome, and infections. All Authors: No reported disclosures