A urinary tract infection (UTI) is one of the most common bacterial infections, typically occurring when microbes, such as Escherichia coli (E. coli), enter the urinary system through the urethra. The infection is usually confined to the lower urinary tract, affecting the bladder in a condition known as cystitis. Since the body’s immune system often cannot eliminate these bacterial colonies alone, targeted antimicrobial medication, usually antibiotics, is required to eradicate the bacteria and prevent the infection from spreading.
Worsening Symptoms and Persistent Bladder Infection
Ignoring the initial signs of a lower UTI, such as pain or a burning sensation during urination (dysuria), allows the bacterial population to multiply unchecked. This significantly increases the severity of symptoms within the bladder and urethra. The persistent urge to urinate becomes more frequent and intense, often yielding only small amounts of urine due to bladder lining inflammation.
The continued presence of bacteria causes irritation and inflammation, resulting in changes to the appearance of the urine. Urine may become cloudy, have a strong, unpleasant odor, or show visible signs of blood (hematuria). As the infection progresses locally, discomfort in the lower abdomen and pelvic region escalates to constant, noticeable pain.
Infection Spreads to the Kidneys
The most common serious complication of an untreated UTI occurs when bacteria travel upward from the bladder through the ureters to the kidneys. This condition is known as pyelonephritis, a severe infection of the upper urinary tract. Unlike a simple bladder infection, pyelonephritis involves the delicate filtering units of the kidneys and presents with distinct, systemic symptoms.
The severe infection in the kidney tissue triggers a strong inflammatory response that manifests as high fever and uncontrollable shaking or chills. Individuals often experience intense pain in the flank, which is the side and back area just below the ribs. Nausea and vomiting frequently accompany these symptoms, making it difficult to maintain hydration. Pyelonephritis requires immediate medical attention and often necessitates hospitalization for intravenous antibiotics to prevent further degradation of kidney function.
The Risk of Systemic Blood Poisoning
If the kidney infection is not treated promptly, bacteria can breach blood vessels within the kidney tissue and enter the bloodstream. This progression leads to urosepsis, a life-threatening form of sepsis originating from the urinary tract. Sepsis is the body’s overwhelming and damaging systemic response to the infection, rather than the infection itself.
Once bacteria and their toxins circulate throughout the body, the resulting widespread inflammation can cause organs to malfunction. Urosepsis symptoms are acute and represent a medical emergency, including a rapid heart rate, very low blood pressure (hypotension), and mental confusion. If the body’s response causes circulatory collapse, it can quickly progress to septic shock, resulting in organ failure and carrying a significant risk of death.
Long-Term Damage and High-Risk Scenarios
Even if an acute infection is overcome, severe or repeated pyelonephritis can lead to permanent structural changes within the kidneys. Inflammation and tissue destruction can result in scarring of the kidney’s filtering units, diminishing their ability to clean the blood. This irreversible damage contributes to the development of chronic kidney disease (CKD) over time, potentially requiring dialysis or a transplant in advanced stages.
Specific populations face heightened risks when a UTI goes untreated. For pregnant women, an untreated infection is associated with complications like increased risk of preterm labor and low birth weight. Individuals with underlying conditions such as diabetes have a greater chance of developing severe infections due to impaired immune response. Those with kidney stones or other urinary tract obstructions are at higher risk for the infection to rapidly ascend and cause severe kidney damage. Chronic inflammation in the lower tract can also lead to issues like urethral narrowing in men due to scar tissue formation.