Most . Most bladder infections are caused by bacteria from the genital/anal area that get into the urethra and then the bladder. The most common reasons for a woman to develop an infection are: - poor hygiene: you always want to wipe "front to back" to avoid rubbing fecal bacteria over your vaginal and urethral areas - sexual activity: the act of sex can push bacteria into the urethra - you can avoid this by always peeing right after sex to flush it out - bad luck if you suspect a urinary tract/ bladder infection, you should call your doctor to be seen. Your doctor may want to check a urine sample to see if you are infected and what kind of bacteria has caused it. This can help the doctor know which antibiotic will work best for you.