“My father has been diagnosed with an infection in the brain. What will be the treatment for this?”

There is no simple answer to this. It depends on the type of infection, and where it is. Obtaining a specimen from the brain for culture is necessary unless he is known to have an active infection somewhere else that is believed to have spread to the brain. It is often helpful to debride the infection (clean up the infection) surgically and then treat afterwards with antibiotics.