We had un'ospite speciale/a special guest: Anna Jasonides R. D., L. D., nutritionist from MIT medical. She made a great presentation about la dieta mediterranea: what it is, what are its benefits, and examples from the Greek cuisine.
The noun ospite can be used for a masculine or feminine guest, but you would use a different (indeterminative) article. Una ospite -> un'ospite (f) vs un ospite (m, without apostrophe).
Mediterranean Diet Lecture Slides (PDF - 2.1MB) (Courtesy of Anna Jasonides. Used with permission.)
(There is a small error in the text: Italians would say "Ha sempre fretta" not "Sempre ha fretta".)
Espresioni Con Avere