Guidelines are available from the Infectious Disease Society of America and the American College of Gastroenterology.
Here are some points of interest from the guidelines. These represent an oversimplification and readers are referred to the original documents, which are available at the above links as free full text. The IDSA version is a bit dated but an update is anticipated next year. Therefore the comments below focus mainly on the ACG guidelines.
The two guidelines differ slightly in their categorizations of severity of disease.
Severe disease is defined as leukocytosis (15,000) OR cr of 1.5 X baseline in the IDSA document; it is defined as albumin below 3 AND either leukocytosis (15,000) or abdominal tenderness according to ACG. Both guidelines denote the additional category of severe-complicated for patients with severe disease plus either findings of hypoperfusion (in terms of blood pressure or lactic acid level) or evidence of gut functional disturbance that calls for added alternative means of drug delivery (ileus, megacolon).
The treatment recommendations are similar in both guidelines.
Mild disease: metronidazole 500 mg PO TID.
Severe disease: vancomycin 125 mg PO QID.
Severe-complicated: vancomycin 500 mg PO or NG QID plus metronidazole 500 mg IV Q8H with or without vanc enemas.
The ACG guideline mentions the FDA approval of fidaxomicin but does not include it in the treatment recommendations.
Fecal transplant is recommended for consideration in the event of a third recurrence.
The guideline does cite the NEJM study from last year and noted an NIH sponsored trial which is underway, looking at patients with a second recurrence.
Patients with inflammatory bowel disease (IBD) hospitalized with a flare should be tested for C diff.
Immunosuppressive treatment can continue in IBD patients infected with C diff provided adequate treatment for the C diff is in place.
IBD patients with a severe colitis flare should be considered for expectant C diff treatment pending test results, as should any patient in which there is a strong clinical suspicion.
Potentially inciting antibiotics should be stopped if possible.
What if concomitant antibiotics can't be stopped? According to this study they don't preclude successful treatment but they are associated with modestly lower cure rates, longer time to resolution and an increased relapse rate. The study results suggested that fidaxomicin was superior in that situation.