Would hospital staff do anything differently, in the treatment of meningitis and pneumonia, if the patient were an alcoholic? Is that knowledge itself crucial to the care and treatment of these conditions?
Alcoholics have lazy leukocytes, they may not fight off infection as well.
Also, if the person is truly addicted to alcohol, cold-turkey withdrawl can be life-threatening all by itself. I saw a guy who had a seizure so bad he broke a bunch of teeth. There are medications to ease withdrawl, but the doctors have to know.
Tell the doctors. They are required by law to maintain confidentiality.