I call the MD Dr._______ unless they ask me to call them by their first name. Years ago, I worked on an antepartum unit and all the physicians wanted to be addressed by their first names only. In the OR, they wanted Dr. until the pt was asleep, then it was first names.
I started as a CNA in 1980 and in a very catholic hospital. When a Dr. entered the unit, all nurses, etc. got up and gave them their spots. Also, they had private dining, completely stocked and private sleeping areas and we were not to disturb them.
Then again, we also lit their cigarettes for them and emptied their ashtrays......hahaha!
Times are changing, but, I feel if they went to school THAT long and take on that kind of responsibility, I will call them doctor.