In the example you sited, the use of the italics draws attention to the single word and thust when you read it, you are suppose to stress that single word.
Be, I only use italics in stories where I want to show internal thoughts without all the he/she thought stuff noted.
In my current fantasy novel, I use italics to show mind-link between individual instead of showing it as dialogue. Therefore, I can not use the italics to show internal thoughs and have to rely on the old...he supposed, he thought, etc, etc.
Whatever device you use to stress a word or show something else, you should keep the use uniform and not mix the uses. IMHO. I read a detective novel once that used italics for many things and it got confusing on what the hell I was suppose to be seeing, reading, saying...