E. coli in the urine usually indicates a urinary tract infection (UTI), which can range from mild to serious depending on the extent of the infection and whether it spreads to the kidneys. In most cases, an E. coli UTI causes symptoms like frequent, urgent urination, burning during urination, and cloudy or blood-tinged urine. However, if the infection spreads to the kidneys, it can become much more serious, leading to fever, upper back pain, nausea, and possibly kidney damage. Some strains of E. coli produce toxins that can cause severe complications such as kidney failure, but these are less common. Untreated or recurrent E. coli urinary infections can lead to repeated infections or kidney damage, which requires prompt medical treatment to avoid serious outcomes. Antibiotic resistance is a concern, so urine culture tests are important to select effective treatment. Overall, E. coli in urine is a common but potentially serious condition that requires medical attention to prevent complications.