Pyelonephritis is a kidney infection that is more common in women. It is caused by E. coli bacteria ascending from the genital area to the kidneys. The urinary system includes the kidneys, ureters, bladder, and urethra. Urine is filtered by the kidneys, stored in the bladder, and expelled through the urethra. Risk factors for pyelonephritis include urinary tract infections, surgeries, abnormalities, kidney stones, and conditions obstructing urine flow. Symptoms include side, back or groin pain, frequent urination, burning pain, fever, nausea and vomiting, and bloody or pus-filled urine. Treatment involves antibiotics for