Urinary tract infections (UTIs) are caused mainly by bacteria and viruses that enter the urinary tract. There are many factors that can increase the chances of getting a UTI some of them being sexual intercourse especially in women, a weakened immune system due to diseases such as is the case with sickle cell and diabetic patients. Since UTIs are a case of bacteria that enter the urinary tract through the urethra poor toilet hygiene can be the cause. There are also other conditions that can promote the incidence of UTIs which include pregnancy and prostrate gland enlargement in men.
UTIs can be as a result of some allergenic responses to certain foodstuffs. Certain foods can irritate the epithelia of the bladder thus causing it to respond in such a way that it becomes vulnerable to bacterial attack. You can also get UTIs as a result of being allergic to spermicides, contraceptive pills or any other birth control method you will be using.

For the elderly who are using catheters, there is a high chance of developing UTIs as a result of poor aseptic conditions. This will cause bacteria to enter the urinary system through the catheter and is it much easier for the bacteria to multiply in great numbers due to the fact that immunity diminishes with age thus causing urinary tract infection in the elderly.

Bacterial invasion of the epithelia of the bladder and urethra is as a result of the epithelial proteins that play a role in the binding of bacteria being disrupted. This means that when the bacteria enter the urinary tract they do not bind to the walls of the bladder and thus they cannot be destroyed by the immune system. This is so for the bacteria has to first bind to the epithelia before it is engulfed by phagocytosis and is then destroyed by white blood cells. So once these proteins that help in the binding of bacteria are disrupted then the person is at high risk of developing UTIs.

In women UTIs are caused by the fact that their urethra very close to the anus and also that they do not have any prostatic gland which secretes substances that help prevent infection. Vigorous sexual activity has also been linked to the onset of UTIs. This is so because vigorous sexual activity will result in abrasions on the urinary tract which are left exposed to bacteria attack as their protective barrier would have been removed.