Table 6.

American College of Gastroenterology guidelines.⁵

Clinical definition	Recommended treatment in adults
Initial episode, mild-moderate	Metronidazole 500 mg orally TID for 10 days
Initial episode, severe	Vancomycin 125 mg orally QID for 10 days
	Vancomycin should be given in patients who are pregnant, breast feeding, intolerant/allergic to metronidazole or those who have not responded within 5–7 days of metronidazole therapy
	In those unable to take oral antimicrobials: Vancomycin delivered via enema should be added to treatments above until the patient improves
Initial episode, severe-complicated	Those without ileus: Metronidazole 500 mg IV TID in addition to vancomycin 500 mg PO QID.
	Those with ileus or toxic megacolon and/or significant abdominal distention: Give both oral and rectal vancomycin along with intravenous metronidazole.
First recurrence	Utilize the same regimen used in the initial episode (if severe then vancomycin should be given)
Second recurrence	Repeat metronidazole or vancomycin pulse regimen
Third recurrence and beyond	Consider fecal microbiota transplantation

ACG, American College of Gastroenterology; IV, intravenous; PO, by mouth; QID, once per day; TID, three times per day.