Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Urinary Tract Infections in Children ?
    ### Response:
    Most UTIs are caused by bacteria that live in the bowel. The bacterium Escherichia coli (E. coli) causes the vast majority of UTIs. The urinary tract has several systems to prevent infection. The points where the ureters attach to the bladder act like one-way valves to prevent urine from backing up, or refluxing, toward the kidneys, and urination washes microbes out of the body.
    