Intestinal microbiology and urinary tract infection associated risk in long-term aged care residents

Urinary tract infections (UTI) are the most frequently diagnosed infection in residents of long-term care and are a major risk factor for urosepsis, hospitalisation, and death. Translocation of gut pathobionts into the urinary tract is the presumed cause of most UTIs. While specific gut microbiota characteristics have been linked to UTI risk in younger adults, their relevance in aged care residents remains uncertain. The faecal microbiome was assessed in 54 long-term aged care residents with a history of UTIs and 69 residents without a UTI history. Further comparisons were made to microbiome characteristics in 20 younger adults without UTIs. Microbiome characteristics were examined in relation to prior and subsequent UTIs, as well as antibiotic therapy. In long-term aged care residents, prior UTI history and exposure to UTI-exclusive antibiotics do not significantly affect microbiome composition or functional capacity. However, exposure to antibiotics unrelated to UTI treatment is associated with distinct microbiota compositional traits. Adjustment for dementia, incontinence, diabetes, and prior antibiotic use finds no microbiota characteristic linked to UTI development. However, prior UTI is identified as a predictor of future UTIs. Comparison with younger adults identifies greater within-participant dispersion in aged care residents, as well as lower microbiota diversity and altered microbiome functional potential. No association between the gut microbiome and UTI incidence, as has been reported in younger individuals, is evident in long-term aged care residents. Considerable variability in gut microbiome characteristics, relating to high antibiotic exposure and age-related physiological and immunological factors, could mask such a relationship. However, it cannot be discounted that increased UTI risk in the elderly is independent of microbiome-mediated mechanisms. Urinary tract infections (UTIs) are common in residents of long-term aged care facilities, posing serious health risks. Harmful bacteria moving from the gut to the urinary tract is thought to cause most UTIs. It is still unclear, however, how differences in gut bacteria contribute to UTI risk in older adults. Here, we investigate the gut bacteria of aged care residents, both with and without a history of UTIs, and compare them to younger adults. While prior UTIs did not alter gut bacteria, antibiotic use did. We observed greater variability in gut bacteria among aged care residents compared to younger adults. These observations suggest that both high antibiotic exposure and age-related factors may mask any potential relationship between gut bacteria and UTI risk in this population. Understanding these factors could lead to improved UTI prevention and treatment strategies for elderly individuals. Miller et al. investigate the gut microbiome in long-term aged care residents with and without UTI history, as well as younger adults. Findings reveal considerable variability in gut microbiome characteristics due to age-related factors which may mask microbiome-UTI associations.