A urinary tract infection (UTI) is a common bacterial infection that typically begins in the lower urinary system, involving the urethra and bladder. This infection occurs when microbes, most often Escherichia coli (E. coli) bacteria from the digestive tract, enter the urinary opening and begin to multiply. Initial symptoms often include a burning sensation during urination, a sudden and frequent urge to urinate, and passing only small amounts of urine. While UTIs are highly treatable with antibiotics, they rarely resolve on their own, and delaying medical intervention allows the bacteria to spread throughout the body.
Escalation of Localized Symptoms
When a lower UTI, known as cystitis, is left untreated, the localized discomfort rapidly intensifies. Inflammation in the bladder lining becomes more severe, leading to constant and painful urination (dysuria). This chronic irritation results in an unceasing sensation of needing to empty the bladder, even immediately after urination.
The high concentration of bacteria and inflammatory cells causes changes in the urine itself. Urine may appear cloudy or develop a strong, foul odor due to infectious waste products. Persistent inflammation of the bladder wall can cause bleeding, resulting in gross hematuria—visible blood that turns the urine pink, red, or brown. Untreated cystitis stresses the bladder tissue, potentially leading to chronic inflammation or making a person susceptible to recurrent infections.
The Threat of Kidney Infection
The most immediate danger of an untreated UTI is the ascent of bacteria from the bladder up the ureters to the kidneys, a serious condition called pyelonephritis. This progression commonly occurs within a few days to a week after the initial infection takes hold. Once bacteria reach the renal pelvis and kidney tissue, they cause inflammation and infection that differs significantly from a simple bladder infection.
The symptoms shift from localized urinary discomfort to a systemic illness with severe signs. Patients often develop a high fever accompanied by shaking chills and sweating. A hallmark symptom of pyelonephritis is severe pain in the back, side, or groin area, known as flank pain, which indicates the infection is affecting the renal organs. Nausea and vomiting are also common, complicating hydration and oral antibiotic treatment.
A kidney infection requires immediate, aggressive treatment, often involving hospitalization for intravenous antibiotics. If the infection is not quickly eradicated, the intense inflammation can lead to permanent kidney scarring. This scarring reduces the kidney’s ability to filter waste and regulate blood pressure, potentially leading to acute kidney injury or chronic kidney disease.
Life-Threatening Systemic Infection
The most dangerous complication of an untreated urinary infection is urosepsis, a form of sepsis that originates in the urinary tract. Sepsis is a life-threatening condition where the body’s response to infection becomes dysregulated, damaging its own tissues and organs. This occurs when the bacterial infection, typically originating in the kidneys, spreads into the bloodstream.
The body-wide inflammatory response to circulating bacteria and their toxins can rapidly cause organ dysfunction. Symptoms of a progressing systemic infection include confusion, a rapid heart rate, and extreme fatigue. As the condition worsens, it can progress to septic shock, characterized by low blood pressure that prevents oxygen from reaching vital organs.
If the body enters septic shock, the risk of multi-organ failure increases significantly. Organs like the lungs, heart, and brain begin to fail, and the patient may experience a reduction in urine output as the kidneys shut down. Sepsis carries a high mortality rate, emphasizing the necessity of seeking medical care at the first sign of a urinary infection.