I am not a doctor but curious to know!?

Question

If somebody's prostate is full of bacteria, why don't this bacteria spread to another organ, like lungs or liver?

Answer 1

The body is very good at walling off bacteria and preventing it from spreading. It is the same as getting an infected pimple. You may have infection in that one place and the surrounding skin, but your immune system keeps the infection to one place and tries to fight it there (that's why you don't end up in the hospital with pneumonia every time you get a zit). There are times when the infection is too strong (or the immune system too weak) to keep the infection in that one place. In those cases, the bacteria that cause the infection can get into the blood and spread to other parts of the body (or spread to adjoining skin/organs). When your doctor decides whether or not to give antibiotics for an infection, she will look at the likely bacteria that is infecting, the likelihood that the bacteria will be too strong for the body to fight by itself, the apparent strength of your immune system and the length of time that you will be in pain before your body should be able to fight it off on its own. Antibiotics may not always be appropriate treatment (you don't want the cure to be worse than the disease).

Answer 2

The body's immune response eliminates dangerous bacteria by a variety of mechanisms that occur at their site of entry, including neutrophilic and cell-mediated activity, disallowing their spread. If they attempt to spread, a much more vigorous response is summoned by the immune system, manifest as systemic inflammation, complement-mediated, and antibody-mediated activities that serve to destroy pathogenic bacteria.