Could you tell me what are some leads to of urinary infections?

See below: Kidney infection or pyelonephritis can be caused by infected kidney stones or an obstructing ureteral stone by vessico-ureteral reflux or a large post-void bladder residual or by spread through the blood stream.. Bladder infections or cystitis are from bacteria ascending the urethra into the bladder this can be precipitated by sexual contact (honeymoon cystitis). Urinary catheters etc.