At one large hospital, my general orientation included a powerpoint presentation by the infection control nurse. She included GRAPHIC photos (identifying information removed, of course) illustrating various infections with comments on how they happened, and how they should be treated. Some were caused by hospital staff having poor hand hygiene, some by inadequate care, and a few were related to the condition being treated. She also read a few first-hand accounts from healthcare workers who had contracted diseases when treating a patient with ungloved hands, or because of improper disposal of sharps.
I think this would work- I've used examples of what I heard in this class when I've given infection control inservices, and they made lasting impressions. One of the examples we were given involved a CNA in a nursery where all the babies were ending up with MRSA infections; they finally traced it back to her- she had a chronic open sore on her forearm and wore a sweater over her scrubs to cover it. The sweater stayed at work and was obviously never washed, and bacteria from the sore had spread down to the cuff of her sleeve.