Scientists have identified a concerning capability in Klebsiella pneumoniae, a bacterium commonly associated with urinary tract infections (UTIs). This pathogen, normally found in the intestines, can adapt and spread to the brain, leading to potentially fatal abscesses.
In a recent case report from Germany, researchers detailed the case of a 63-year-old woman who presented with a UTI and sudden vision loss. Medical scans revealed inflammation in her eye and lesions in her brain, specifically in the parietal lobe. Samples taken from her urine and within her skull all tested positive for Klebsiella pneumoniae. Critically, two of these samples contained an "evolved" strain of the bacteria, distinguished by a slime capsule that aids in evading the immune system and facilitating its spread throughout the body.
Fortunately, the woman's infection was successfully treated with antibiotics. Researchers noted that the more aggressive strain may have developed over a period of one to two years, as the patient had been treated for a UTI two years prior. The study suggests that such bacterial evolution can occur within a patient's existing infection, leading to the emergence of genetically distinct subpopulations that are better equipped to spread or resist antibiotics.
"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 who led the research. "We therefore suspect that [virulent] populations are especially prevalent in multidrug-resistant infections."
While it remains unclear if the evolved bacteria directly caused the brain infection, its enhanced ability to evade the immune system increases the risk of infecting other organs. The exact mechanism by which the bacteria reaches the brain is also unknown, though one theory proposes the eye as a potential entry point, with bacteria transferred by contaminated hands.
This phenomenon, termed "heterovirulence" by the researchers, describes the emergence of a more virulent bacterial strain that, while possibly outcompeted in one area (like the urinary tract), excels at spreading to and infecting other parts of the body, such as the eye. The findings were published in the New England Journal of Medicine.
In the United States, approximately eight million UTIs are recorded annually, with Klebsiella pneumoniae accounting for at least one million of these. Individuals with weakened immune systems, diabetes, or those who have recently undergone surgery are at a higher risk of developing severe infections. Women are generally more susceptible to UTIs due to their shorter urethra.
The bacterium poses a significant challenge in hospital settings, where it can persist on surfaces and spread among vulnerable patients. Transmission typically occurs through contact with contaminated feces followed by touching other body parts or through contaminated medical devices. 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 the infection is usually treatable with antibiotics.