 ii. Exclusion criteria Patients will be ineligible for the study if they have had peritonitis within the previous 4 weeks, clinical signs or symptoms of active infection, elevated white blood cell count, or treatment with any antibiotic within the previous 2 weeks. Patients with a hemoglobin hgb 11 gdL will be ineligible for study inclusion. Patients with stated or documented allergies to beta-lactams medications will not be eligible. Pregnant or breastfeeding women will not be eligible for inclusion. All women of child-bearing age will need to yield a serum hCG 5 mIUmL within 2 weeks of the scheduled study day. Patients taking valproic acid will also be excluded. 