Bacteria responsible for frequent urinary tract infections (UTIs) can evolve and spread to the brain, potentially leading to life-threatening abscesses, according to a new case report.
Klebsiella pneumoniae, a bacterium commonly found in the intestines, can cause infections when it enters other parts of the body, such as the urinary tract. While often treatable, it can lead to severe complications like sepsis and tissue death in serious cases.
Scientists in Germany documented a case involving a 63-year-old woman who was admitted to a hospital with a UTI and sudden vision loss in one eye. Medical imaging revealed inflammation in her eye and lesions in her brain, specifically in the parietal lobe, which processes sensory information. Samples from her urine and the abscess within her skull all tested positive for Klebsiella pneumoniae.
Researchers identified an "evolved" strain of the bacteria in two of the samples. This strain possessed a slime capsule, enabling it to evade the immune system and proliferate more effectively within the body. The woman was successfully treated with antibiotics.
Scientists noted that the woman had been treated for a UTI approximately two years prior, suggesting the more virulent strain may have evolved within her over that period. This phenomenon, termed "heterovirulence" by the researchers, describes how a subpopulation of bacteria can develop traits that enhance its ability to spread to other organs, even if it is less successful in its original site of infection.
"Our findings show highly virulent [bacteria] can evolve within an apparently harmless reservoir such as a urinary tract infection," stated Dr. Christoph Ernst, a microbiologist involved in the research. "We therefore suspect that [virulent] populations are especially prevalent in multidrug-resistant infections."
While it is unclear how the bacteria reached the woman's brain, one theory suggests the eye could serve as an entry point if bacteria are transferred by contaminated hands. The evolution of the bacteria may have increased its likelihood of infecting other organs.
There is currently no evidence to suggest that this evolved strain is spreading between individuals. The New England Journal of Medicine published the case report detailing these findings.
UTIs are common in the United States, with an estimated eight million cases recorded annually, at least one million of which are attributed to Klebsiella pneumoniae. Individuals with weakened immune systems, diabetes, or those who have recently undergone surgery are at higher risk of developing infections. Women are more susceptible to UTIs due to their shorter urethra.
Klebsiella pneumoniae can pose a particular challenge in hospital settings, where it can persist on surfaces and spread among vulnerable patients. Transmission can occur through contact with contaminated feces and then touching bodily openings or wounds, as well as via contaminated medical equipment.
Symptoms of a UTI can include painful or difficult urination, pain in the urinary tract, fever, and chills. Medical professionals advise consulting a doctor if a UTI is suspected, as infections are typically treated with antibiotics.