Cystitis occurs when the lower urinary tract (urethra and bladder) is infected by bacteria and becomes irritated and inflamed. More than 85% of cases of cystitis are caused by Escherichia coli (E. coli), a bacteria found in the lower gastrointestinal tract. Sexual intercourse may increase the risk of cystitis because bacteria can pass from the urethra to the bladder during sexual activity. When you urinate, you help remove bacteria from the bladder. If the bacteria grows faster than it is removed by urination, an infection results. The condition is very common, and frequently affects sexually active women ages 20 to 50. However, it may also occur in those who are not sexually active. Cystitis is rare in males. Women are more prone to develop cystitis because they have shorter urethras than men, and bacteria does not have to travel as far to enter the bladder. The distance between the opening of the urethra and the anus is also shorter in women than men. Older adults are also at high risk for developing cystitis. Rates of cystitis are much higher among the elderly than in younger people. This is due in part to conditions that cause an incomplete emptying of the bladder such as benign prostatic hyperplasia (BPH), prostatitis, and urethral strictures. Not drinking enough fluids, bowel incontinence, and immobility or decreased mobility, increased one's risk for cystitis. Other risk factor for cystitis include blockage of the bladder or urethra, insertion of instruments into the urinary tract (such as catheterization or cystoscopy), pregnancy, diabetes, HIV, and a history of analgesic nephropathy or reflux nephropathy. | 
General Urology, Renal Disease
