Bladder Infection (Cystitis)

Medical Author:
Medical Editor:

What is a bladder infection?

Bladder infection is an infection of the bladder. Bladder infection is also called cystitis and is a type of urinary tract infection (UTI). The urinary tract is naturally sterile and when microbes invade it, an infection may result.

The bladder is a part of the urinary tract system. It serves as storage for urine before it is excreted from the body. Urine is produced by the kidney and it travels through ureters (one from the right kidney and one from the left) to pass into the bladder. The urine can then be eliminated from the body when bladder is full. The bladder contracts to empty its contents outside through the urethra (the connection between the bladder and outside of the body). Urethra length traverses the length of the penis in males, thus it is longer than the urethra in females.

What causes bladder infections?

Similar to other fluids in the body, urine is normally sterile. Presence of bacteria in the urine may lead to bladder infection and other forms of urinary tract infection.

The most common way bacteria gain access to the urinary system from outside is through the urethra (the drainage from the bladder to outside of the body).

  • Bacteria can travel from the rectum or the vagina towards the urethra to enter the bladder causing bladder infection or cystitis.
  • Sometimes bacteria may enter the bladder via the urethra from nearby skin.
  • In general, women are more susceptible to bladder infections due to their shorter length of urethra.

In terms of specific bacteria, E. coli. (Escherichia coli) is by far the most common organism responsible for bladder infection or cystitis. Staph organisms (from skin) and other gut bacteria (Proteus, Klebsiella, Enterococcus) are other bacteria that can cause cystitis and other forms of urinary infections.

Rarely, bladder infection can be caused by a fungus. Candida is the most common fungus to cause bladder infection. This can occur in patients with untreated kidney stones with recurrent infections or in individuals whose immune system is compromised.

Medically Reviewed by a Doctor on 7/10/2014

Patient Comments

Viewers share their comments

Bladder Infection - Symptoms Question: What symptoms did you experience with bladder infection?
Bladder Infection - Treatment Question: What kind of treatment did you have for your bladder infection?
Bladder Infection - Children Question: If your child had a bladder infection, please describe the symptoms that led to a diagnosis.
Bladder Infection - Prevention Question: If you've had a bladder infection, what do you do to prevent another one?