A kidney infection, also known as pyelonephritis, occurs when bacteria enter the kidneys, often through the urinary tract. This can happen if a bladder infection spreads or if bacteria travel up from the urethra. Symptoms may include fever, back pain, and painful urination. It's important to treat kidney infections promptly to prevent complications. Treatment usually involves antibiotics to eliminate the infection. In some cases, hospitalization may be necessary, especially if the infection is severe. Drinking plenty of fluids can help flush out the bacteria. If you experience symptoms, it's essential to consult a healthcare professional for proper diagnosis and care.