Clinical questions to be addressed:What is the initial approach to working up diarrhea in the hospitalized patient, and should empiric therapy be begun while awaiting results?How should recurrent C. difficile infection be managed?How should diarrhea be handled in the ambulatory setting? What is the role of phone-call management of diarrhea?In the traveler, what is the most judicious and practical means of prophylaxis, and when and with what agent should therapy be begun if diarrhea develops?