Whats the cause for uti?

Bacteria: Most urinary tract infections (UTI) are secondary to bacterial infection in the bladder. E coli is the most common bacteria causing uti. But don't be fooled...Sometimes people can have symptoms like a UTI (frequency, urgency, pain, etc) and not have an infection. Not all cystitis (bladder irritation) is caused by bacteria.

Many things: Sometimes they just happen, just like a cold. It depends on your sex and age! if they happen over and over again there is something majotly wrong. If it just happened once its probably not a big deal. You should see a health care provider if you are worried.

Bacteria in bladder: Bacteria multiply in bladder consuming urinary nutrients. They enter during sex, thus need to urinate after sex. With poor toilet technique - wiping back to front, or keeing thighs closed with urination thus trapping urine behind labia. Wearing thong or non-cotton underwear. Withholding urination after bladder is full. Using bubble-bath or taking long tub baths. Constipation.