Why do utis accur?

Bacteria: Bacteria can ascend the urethra and cause bladder infection. Because there are a lot of bacteria in the region, bacteria can climb up and cause infection. Women have shorter urethra so have more frequent utis than men. Certain medical conditions such as immunosupression can increase risk of utis.

Bacteria & Subject: Bacterial factors are ability to resist body's natural defense mechanisms, to travel if cilia present (like tiny hair on a caterpillar) and speed of multiplication.Subject factors: presence of bacteria at urinary opening, in women -presence of immunoglobulins in women from vagina & short urethra & urinate after sex, efficiency & frequency of bladder emptying & lining to resist invasion of bacteria.