Prostate infections: What's the cause?

I have had bouts of pain at the base of my penis for several months, and recently my semen was slightly brown in colour. Ibuprofen takes the pain away, but it comes back in a day or two. After urine tests and a rectal examination, I have been diagnosed with an infection of the prostate gland. The PSA blood test is slightly raised, but I was told this is due to infection, not cancer. What causes prostate infections? I have been put on antibiotics for eight weeks, which seems a long course. I am 38 years old and healthy, and I cycle at least 30 miles a week.

Dr Fred Kavalier answers your health question:

Prostate infections and inflammations are all called the same thing prostatitis. Sometimes the infection is bacterial, but often no harmful bacteria can be identified. Prostatitis can be acute and severe, or more of a grumbling chronic condition. The usual symptoms are pain, difficulty and pain when you pass water and ejaculate, and occasionally blood in the semen. The brownish colour of your semen is likely to be a small amount of blood. Usually it is impossible to discover why a man gets prostatitis. Bike and horse riding, which can put pressure on the prostate gland, sometimes seem to be culprits. The best treatment is with antibiotics, and it can take many weeks to get rid of it. Sometimes the symptoms return and it's necessary to carry on with a low dose of antibiotics for months, or even indefinitely. Prostatitis can cause an abnormal PSA blood test, so it's very unlikely that there is an underlying prostate cancer. Think about changing your bicycle saddle to one that does not put pressure on your prostate gland.

Please mail your questions for Dr Fred to health@independent.co.uk. He regrets that he is unable to respond personally to questions.