Study Links Gut Bacteria Infections to Alzheimer’s Progression

A new study has uncovered a potential connection between gut infections and the progression of Alzheimer’s disease, raising critical questions about the gut-brain axis in neurodegenerative disorders. The research, conducted by the Florida State University’s (FSU) Gut Biome Lab, points to the common bacteria Klebsiella pneumoniae as a possible contributor to Alzheimer’s symptoms through its migration from the gut to the brain.

According to the study, published in The Journal of Infectious Diseases, Klebsiella pneumoniae is a bacteria often responsible for hospital-acquired infections. Researchers found that the bacteria can travel from the digestive system to the brain. Once there, researchers explained that it could trigger inflammation and impair cognitive functions, which closely resemble the hallmark symptoms of Alzheimer’s. The study, led by Ravinder Nagpal, MSc, PhD, is the first to directly link K. pneumoniae infection with Alzheimer’s pathology.

“Hospitalizations and ICU stays, combined with antibiotic exposure, may lead to a further decline in microbiome diversity that leaves older adults at high risk not only for digestive issues but also for extra-intestinal pathologies such as neurodegenerative disorders through a dysregulation of the gut-brain axis,” said Dr. Nagpal, who is assistant professor and director of the Gut Biome Lab at FSU.

In the study, researchers used a mouse model to demonstrate how antibiotic exposure can reduce gut microbial diversity, allowing harmful bacteria like K. pneumoniae to thrive. According to researchers, this creates an environment in which the bacteria can penetrate the gut lining, enter the bloodstream, and eventually affect the brain.

“Hospital-acquired and septic infections are one of the risk factors that may increase the predispositions to future neuroinflammatory and neurocognitive impairments, especially in older adults,” said Dr. Nagpal.

Beyond the conventional focus on amyloid plaques and tau proteins, researchers said these findings introduce a new avenue of inquiry into how gut health and infection control might play a role in Alzheimer’s disease prevention and management. For integrative practitioners, this research underscores the importance of maintaining a healthy microbiome, especially in aging populations or individuals recovering from severe infections or hospital stays.