This is a research study to collect information from people that have Clostridium difficile infection (CDI) and are treated with a standard antibiotic treatment in which the antibiotic dose is gradually reduced over 6 weeks and bezlotoxumab (BEZLO), an approved monoclonal antibody targeting C. difficile toxin, which has shown to reduce CID recurrence when used in combination with standard antibiotic treatment.

Clostridium difficile (C. diff) is a type of bacteria which causes diarrhea in some people who receive antibiotics for other infections. The current antibiotics used to treat C diff infection (CDI) are usually successful in treating the initial episode of CDI, but may not prevent recurrent infection. To prevent recurrent CDI, standard oral antibiotic treatment with vancomycin is extended by gradually reducing the dose over 4-8 weeks. This is called antibiotic taper. Bezlotoxumab (BEZLO), a monoclonal antibody targeting C. difficile toxin B, is an approved medication that has also been shown to reduce CDI recurrence in patients receiving antibacterial drug treatment of CDI. In this study, approximately 12 people with multi-recurrent CDI will be treated with BEZLO in combination with standard oral tapered vancomycin. Study participation will last 16 weeks. The rate of CDI recurrence in this group will be compared to information collected from approximately 72 historical patients with multi-recurrent CDI treated with oral tapered vancomycin only.

Inclusion Criteria (Interventional):

• i) age 18 years or older;
• ii) diagnosis of multi-recurrent CDI, defined as passage of 3 or more loose stools in 24 hours or less for at least 2 consecutive days and a positive stool test for toxigenic C. difficile (nucleic acid amplification test [NAAT] and toxin enzyme immunoassay [EIA] positive), with 2 or more confirmed prior CDI episodes;
• iii) receiving or planning to receive a 10- to 14-day course of SOC therapy with oral VAN followed by a tapered VAN regimen for at least 4 weeks;
• iv) patient highly unlikely to become pregnant due to being female and not of reproductive potential or female of reproductive potential agreeing to be abstinent or using 2 acceptable methods of birth control starting at enrollment and through the 16-week study period; and
• v) patient or legal representative voluntarily agreeing to participate by providing written informed consent after the nature of the study has been fully explained.

Inclusion Criteria (Historical Control):

• i) age 18 years or older
• ii) diagnosis of multi-recurrent CDI
• iii) received 10- to 14-day course of SOC therapy with oral VAN followed by a tapered VAN regimen.

Exclusion Criteria:

• i) active chronic diarrheal illness, such as (but not limited to) ulcerative colitis or Crohn's disease or with a condition such that they routinely pass loose stool
• ii) planned surgery for CDI within 24 hours
• iii) positive pregnancy test in the 48 hours before the infusion or unwilling to undergo pregnancy testing if a pre-menopausal female who is not sterilized and therefore has the potential to bear a child
• iv) breastfeeding or planning to breastfeed prior to the completion of the study period
• v) previous receipt of BEZLO
• vi) receipt of immune globulin within 6 months prior to enrollment or planning to receive immune globulin prior to completion of the 16-week study period
• vii) receipt of non-SOC CDI therapy within 14 days prior to enrollment
• viii) planned treatment with SOC therapy for longer than 6 weeks
• ix) receipt of medications to control diarrhea such as loperamide, diphenoxylate hydrochloride/atropine sulfate at any time prior to completion of the 16-week study period
• x) medical history of decompensated congestive heart failure