If possible, the first step in treating CDI may be discontinuing the antibiotics that are currently given. Discontinuing antibiotic therapy may restore the balance of the natural gut flora and allow the digestive system to resume its normal functions. Fluids and electrolytes are normally administered to maintain hydration. Stopping antibiotic therapy may alleviate symptoms in some patients, but most require further treatment.

Antimicrobials such as oral vancomycin and metronidazole are prescribed to fight C. difficile bacteria. These drugs also disrupt the normal gut flora, which may contribute to recurrent CDI infection. Depending on your risk factors as well as the severity of the disease, several rounds of treatment may be necessary before you are able to rid yourself of CDI.

Metronidazole is considered as a first-line antimicrobial therapy to treat CDI because it is inexpensive, but has side effects such as nausea and vomiting and is administered orally four times daily for 10 to 14 days. Patients who are pregnant or breast-feeding are recommended not to take metronidazole.

Vancomycin® is the only FDA-approved therapy to treat CDI. Studies show it is more effective than metronidazole and is associated with fewer side effects. However, Vancocin® may contribute to the development of vancomycin-resistant enterococcus (VRE) in the intestine. For patients who are pregnant or unresponsive to metronidazole, doctors typically prescribe Vancocin® four times daily for 10 to 14 days. Generic vancomycin has also been prescribed in hospitals in the form of “slurries” in which the intravenous formulation of vancomycin is mixed as drink for ingestion.

To treat persons who have relapsed on at least two occasions, bacterial flora from the stool of a healthy donor is introduced into the digestive system through a tube into the stomach in an attempt to normalize the balance of the flora in the large intestine. The procedure has not gone through sufficient study to know its success rate. There may be a risk of transmitting retroviruses or other infectious agents to patients undergoing the procedure.

CDI can result in organ failure or inflammation of the lining of the abdominal wall. In such serious cases, surgery to remove the diseased portions of the bowel (colectomy) may be the only option.

ACAM-CDIFF (Sanofi-Aventis)

ACAM-CDIFF is the only vaccine in development against /Clostridium difficile/ bacteria. It is currently conducting a Phase 2 clinical trial in the UK and recruiting patients for a Phase 2 clinical trial in the U.S.

CDA-1 + CDB-1 (Medarex/Merck)

Phase 2 clinical trial showed that adding two therapeutic monoclonal antibodies to standard antibiotics reduced the rate of recurrent CDI. The antibodies were administered together, each at a dose of 10 mg per kilogram of body weight, in patients with symptomatic CDI who were receiving either metronidazole or vancomycin.

CB-183,315 (Cubist)

Cubist Pharmaceuticals completed multiple trials evaluating dosage of a leipopeptide, and is currently in Phase 2 clinical trial.

Fidaxomicin

Fidaxomicin, also known as OPT-80, PAR-101 or difimicin, recently completed its Phase 3 studies that together represent the largest database of CDI clinical trial data in the world and largest comparative studies ever conducted against Vancocin. Optimer Pharmaceuticals plans to submit a New Drug Application to the FDA in the second half of 2010 and is also preparing a Marketing Authorization Application for submission to the European Medicines Agency, or EMA. The company is also developing an oral suspension formulation to complement the existing tablet form of fidaxomicin. This formulation is intended for use with intensive care unit and elderly patients who cannot swallow tablets.

Intravenous immunoglobulin

Intravenous immunoglobulin (IVIG) is derived from the plasma of healthy donors and has been used for several indications including primary immunodeficiency and idiopathic thrombocytopenic purpura. It has been used to treat C. difficile infections; however, there is not enough evidence to prove its effectiveness.

NTCD (ViroPharma)

NTCD is a non-toxic strain of C. difficile that repopulates a patient's GI tract after antibiotic treatment gets rid of the harmful bacteria. NTCD is intended to be used in conjunction with Vancocin, also marketed by ViroPharma.

Nitazoxanide (Romark Laboratories)

Nitazoxanide is a nitrothiazole compound that has demonstrated its ability to treat both interstitial protozoal and helminthic infections, including Giardia lamblia. It is effective against C. difficile and has been studied in Phase 3 for treating CDI. Branded as Alinia, nitanoxanide has been a commercial diarrhea treatment for more than a decade. Romark stopped a Phase 3 trial in 2008 because of slow recruitment, according to Clinicaltrials.gov.

Rifaximin (Salix)

Rifaximin is a semi-synthetic derivative of rifamycin,and is a treatment for travelers' diarrhea caused by noninvasive strains of Escherichia coli. Branded as Xifaxan, rifaximin has been a commercial treatment for travelers' diarrhea, and is also FDA approved for use in patients with hepatic encephalopathy (HE). Rifaximin has good in vitro activity against C. difficile and completed a Phase 3 clinical trial in December 2008.