The study is based on the hypothesis that decreased creatinine clearance may be associated with detectable vancomycin levels in patients on enteral (oral / vancomycin enemas) vancomyicn for CDAD.

The objective of the study is to see whether enteral vancomycin is absorbed through the inflamed GI mucosa in CDAD, and if it is absorbed, does it achieve measurable serum concentration.

Vancomycin is a large glycopeptide compound with a molecular weight of about 1450 Da. It is not appreciably absorbed orally and is eliminated primarily via the renal route. Enteral vancomycin therapy (oral/intracolonic ) is used inpatients with severe Clostridium difficile associated colitis who are unable to take oral metronidazole or have failed treatment with metronidazole. Oral vancomycin is not detectable in serum of normal persons, but concentrations below therapeutic range may be found in patients with colitis. There are a few case reports of serum concentrations within the therapeutic range after oral/intracolonic administration of vancomycin, in association with renal failure. The use of enteral vancomycin in our geriatric population with variable creatinine clearance prompted us to measure the serum vancomycin levels in these patients.

Inclusion Criteria:

• Patients on enteral vancomycin therapy

Exclusion Criteria:

• Coadministration of intravenous vancomycin therapy,intravenousvancomycin administration in previous10 days.

Patients with Clostridium difficile associated colitis on enteral vancomycin therapy