When bacteria with a painful kick establish residency in the human bladder. Bladder infections are more common in women than men, one reason for this is because the passageway from the bladder to the outside of the body is much shorter in women, allowing bacteria easier access. Other reasons include the close proximity of the urethral opening to a woman’s anus (more than 50% of women’s bladder infections are caused by E. Coli bacteria from the butt); also the tissue around the opening of a woman’s urethra (external urethral meatus) is fairly thin and can easily become irritated and host to infections that can get into her bladder. Bacteria from a woman’s vagina can also cause some bladder infections.