If you have a look at the Italian press or listen to the news, you’ll notice that politicians and other personalities are all referred to by their surname or by name and surname: no title such as signor or signora is added. If a politician is a minister, you may notice the word Ministro, in front of a surname, or the word Onorevole for a member of the Camera (the chamber of deputees). Senatore is reserved to members of Senato:
Il ministro Germini
Il senatore Andreotti
The prime minister is usually referred to as "il premier” + their surname, for instance: il premier Berlusconi
The president of the republic is commonly referred to "Presidente della Repubblica" or “Presidente + surname”. Occasionally he is simply addressed by surname (particularly after he has already been called “Presidente” at least once the beginning of the report). His wife is normally addressed to as "signora" + "christian name:
Il presidente Napolitano ha visitato il luogo del terremoto. Napolitano ha poi incontrato i familiari delle vittime.
President Napolitano visited the earthwake site. He then met the victims’ relatives.
Il presidente Ciampi e sua moglie, la signora Franca
President Ciampi and his wife, Mrs Franca