Urinary Tract Infection II: Pathophysiology

The pathophysiology of a urinary tract infection involves several stages:

Bacteria, typically from the gastrointestinal tract, such as Escherichia coli, can migrate to and colonize the periurethral area.

This colonization often results from poor hygiene, urinary catheterization, urinary stasis from a neurogenic bladder, or conditions like diabetes.

After colonizing the urethra, the bacteria can ascend into the bladder, multiply, and cause a lower urinary tract infection known as cystitis.

Bacteria form biofilms to evade the body's immune defenses. These protective structures shield them from immune cell attacks, allowing the bacteria to persist and multiply within the bladder.

If the infection is left untreated or progresses, bacteria may ascend further through the ureters to the kidneys, resulting in pyelonephritis, an upper urinary tract infection.

As the bacteria proliferate, they produce toxins that directly damage urinary tract tissues.

In severe cases, the bacteria may cross the epithelial barrier of the renal tubules, gaining access to the bloodstream, which can result in bacteremia and potentially lead to sepsis.