Cefepime Pharmacokinetics in Liver Transplant Recipients in an Intensive Care Unit

Inclusion Criteria: * Women and members of minority groups will be included in this study. However, as this study seeks to generate pilot data, there will be no specific statistical analysis comparing differences based on gender or race. * Subjects receiving drugs known to induce or inhibit hepatic enzymes are not excluded from this study as cefepime is renally eliminated and not significantly metabolized by the liver. * All liver transplant subjects are eligible for enrollment in this study, including subjects who have undergone a living related liver transplant. * The pharmacokinetics of cefepime in children are significantly different from those of adults. For the purposes of this study only adults (aged \> 18 years old) will be able to participate. Exclusion Criteria: * Subjects will be excluded if they are anemic (hemoglobin \< 7 mg/dl), or are patients with severe gastrointestinal bleeding who are receiving packed red blood cells. * Subjects who are receiving hemodialysis or other forms of renal replacement therapy (such as continuous veno-venous hemofiltration), or patients with a calculated creatinine clearance of \< 10 ml/min will be excluded from the study.