What causes prostatitis?

Some types of prostatitis are caused by bacterial infection. These cases are often accompanied by the classic symptoms of infection, such as fever, chills, and muscle pain, as well as by urinary problems. As a result, they are relatively easy to diagnose and treat, and they usually respond well to antibiotics. However, such straightforward forms of prostatitis are rare. A report from the National Institutes of Health estimates that bacteria are responsible for only about 5% to 10% of prostatitis cases.

Physicians aren't sure what causes the rest of the cases. Little research has been done in this area, but potential culprits include difficult-to-detect bacteria, such as chlamydia and staphylococcus; immunological and inflammatory processes; depression and stress; and mechanical or neuromuscular problems in the pelvic muscles that irritate the general area.

Most men with prostatitis have chronic prostatitis/pelvic pain syndrome, inflammatory or noninflammatory. The cause of this type of prostatitis is not known.

About 1 out of 10 men have prostatitis caused by bacteria.

Acute prostatitis and chronic bacterial prostatitis - Bacteria infecting the prostate cause acute prostatitis and chronic bacterial prostatitis. Bacteria most likely enter the prostate by:

• Traveling through the urethra.
• Being present in the urine because of a bladder infection.
• Being introduced through the use of a urinary catheter.

Chronic prostatitis/pelvic pain syndrome, inflammatory (nonbacterial prostatitis) - The specific cause of chronic prostatitis/pelvic pain syndrome, inflammatory, is usually not known. But doctors believe the possible causes include:

• Blocked urine flow.
• Abnormal movement of urine and prostate secretions into the prostate.
• Microorganisms that may infect the prostate. If they are present, they usually are not detectable in the urine.
• The immune system attacking the prostate (autoimmune disease).
• Chemicals normally found in the urine, such as uric acid, which may get into the prostate and cause irritation.
• Abnormal nerve or muscle function.

Chronic prostatitis/pelvic pain syndrome, noninflammatory (prostatodynia) - The causes of chronic prostatitis/pelvic pain syndrome, noninflammatory, may be the same as those for chronic prostatitis/pelvic pain syndrome, inflammatory. Some doctors think that a combination of things—including nervous system problems and strained pelvic floor muscles—causes the pain. Emotional problems and anxiety can make the pain worse.