New research from Florida State University reveals how a common, hospital-acquired gut bacteria may contribute to brain inflammation and cognitive decline, particularly among elderly patients exposed to antibiotics during hospital stays.
The study, published in The Journal of Infectious Diseases, demonstrates that in mice, the bacteria Klebsiella pneumoniae can travel from the gut to the brain, potentially triggering inflammation and cognitive problems similar to those seen in Alzheimer’s disease.
Researchers at FSU’s Gut Biome Lab found that when antibiotics disrupt the natural balance of gut bacteria, K. pneumoniae can multiply rapidly and breach the intestinal wall. From there, the bacteria can enter the bloodstream and eventually cross into the brain tissue.
The research team documented severe inflammation in multiple brain regions, particularly the hippocampus and frontal cortex — areas critical for memory and cognitive function. The mice showed increased anxiety-like behaviors and reduced physical performance in mobility tests. Scientists observed that mice given both K. pneumoniae and antibiotics showed significantly higher levels of brain inflammation compared with control groups. These subjects also demonstrated impaired neuromuscular function and cognitive abilities.
“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 Ravinder Nagpal, a co-author of the study and director of the Gut Biome Lab, in a statement from FSU.
The findings raise important considerations for hospital patients receiving antibiotic treatment. According to the study, between 60 and 80 percent of healthcare patients receive at least one antibiotic during their hospital stay.
The research was funded by the Infectious Diseases Society of America and the Florida Department of Health.
