I'd recommend this webinar, it has several ideas and suggestions relevant to your question:
Personally I quite like to use real life case examples, these often surprise the attendees and gets them paying attention and interacting with questions. I.e. if covering hand washing, I'd mention a case when X people were ill in X year when 'Joe' from X company didn't wash his hands after using the toilet/bathroom. I used to have a slide on binary fission which was just text and I'd explain that in certain conditions bacteria can duplicate X times to reach X cells after X hours. I then re-did the slide using a cartoon image of an E.coli cell and usied the animation function on powerpoint to double the numbers every 20 minutes, and had a little clock in the corner reflecting time, so after several clicks the whole screen is covered with hundreds of little cells, and I'd mention general infective dose and symptoms of illness too. I found that the attendees had more attention and reaction when they could see the cells rapidly conquering the screen, rather than me just telling them "after X hours you have X cells". Hopefully this will have a clearer impact with them when they think about contamination and temperature control.