Patients noncompliant with instructions and follow ups could not be completed.

The purpose of this study is to test if metronidazole prophylaxis is effective in decreasing the incidence of hospital induced Clostridium Difficile diarrhea among patients at high risk for this infection.

Clostridium Difficile infection or C. Diff (CDI) is an infection that causes severe diarrhea. Risk factors for this infection include hospitalization, the use of antibiotics, along with medications that decrease the acid in the stomach. This infection leads to a disease which is difficult to treat and can cause serious complications including death in rare cases. This infection also increases medical costs by prolonging hospital stays.

Metronidazole (known by the brand name Flagyl) is an antibiotic that has been available for decades and has been used to treat this disease. Flagyl is approved by the Food and Drug Administration for the treatment of C. diff infection. Recent research by the investigators group has shown that hospitalized patients who took Flagyl had a decreased chance of getting C. Diff infection. However, high quality studies are needed to better evaluate whether the investigators can prevent C. Diff infection in high risk patients with the use of Flagyl.

The purpose of this study is to assess if metronidazole prophylaxis is effective in decreasing the incidence of hospital induced Clostridium Difficile diarrhea among inpatients at high risk for this infection.

High risk patient population are as defined below: taking a broad spectrum antibiotics (piperacillin/tazobactam-Zosyn; Ciprofloxacin).

Inclusion Criteria:

• Inpatients >55
• Proton Pump inhibitor / Histamine-2 Blocker
• On broad spectrum antibiotics (Zosyn and/or Ciprofloxacin). These two antibiotics are selected based on current hospital formulary/use
• Anticipated hospital stay >48 hours
• Mental capacity (able to give informed written consent).

Exclusion Criteria:

• Admission for CDI
• Existing diarrhea at admission
• Passed prophylactic window (>48 hours on broad spectrum antibiotics)
• Unable to take PO at the time of evaluation for study entry
• No more than 14 days of broad spectrum antibiotics anticipated
• Medications with serious interactions/contraindications to that would be taken together with metronidazole (ex. Warfarin, disulfiram, phenytoin, calcineurin inhibitors)
• Inflammatory Bowel Disease
• Admission for colonic bowel surgery or h/o total/Subtotal colectomy)
• Hospice
• Mortality expected <7days
• Previous CDI in the past 6 months
• Intensive care admission due to the difficulty of monitoring them
• Allergy to Metronidazole or other Antibiotics in protocol
• Patients with neuropathy
• History of heavy ethyl alcohol intake(greater than 3 drinks daily) or intake in past 24 hours,Solid organ transplant.

Early termination:

1. Many patients did not comply with the protocol instructions.
2. Lack of resources to conduct the study.
3. Many patients did not respond to follow up calls.