Most diarrheal illnesses due to common bacterial and viral causes are self-limited and do not require antimicrobial therapy.
In otherwise healthy children and adults, symptoms typically resolve within 7 days and therapy should focus on supportive care by replacing fluid and electrolyte losses. In immunocompetent children and adults, empiric antimicrobial therapy is not recommended except in:
1) Infants < 3mo age with a suspected bacterial etiology
2) Severe illness with signs of sepsis (particularly in international travelers)
Empiric antimicrobial therapy may have unintended and potentially harmful consequences, such as increased risk of hemolytic uremic syndrome (HUS) in E. coli O157 infections, antibiotic side effects and allergies, C. difficile infection, and the prolongation of a Salmonella carrier state