Prostatitis - Causes of prostatitis
NHS Choices Medical Reference
It's not known what causes many cases of prostatitis. A bacterial infection is only sometimes responsible.
In many cases of chronic (long-term) prostatitis, doctors can't find any infection in the prostate gland, although they may still prescribe a course of antibiotics. In these cases, the cause is poorly understood.
Chronic prostatitis is thought to be caused by a number of suggested factors, including partial blockage of the flow of urine and underlying problems with the immune system, pelvic floor or nervous system.
Acute prostatitis (when symptoms are sudden and severe) is usually caused by bacteria in the urinary tract entering the prostate.
However, it's less clear what happens in cases of chronic bacterial prostatitis. Doctors aren't certain how bacteria can infect the prostate and cause persistent symptoms that come and go over many months.
One theory is that bacteria spread from the urinary tract or bowel to the prostate and create what's known as a biofilm on the inner surfaces of the prostate. A biofilm is a small but highly concentrated colony of bacteria that's covered by a sticky, protective surface - a bit like the plaque that can sometimes develop on teeth.