Concentration of Ertapenem in Colorectal Tissue

Inclusion Criteria: * Hospitalized patients 18 years or older requiring elective surgical intervention (open or laparoscopic surgery) at the colon will be eligible for this study. * Patients with benignant disorders (e.g. colonic diverticulosis) will be preferred. Exclusion Criteria: * Pregnancy or lactation in women * Emergency surgery, history of serious allergy or intolerance to β-lactam antibiotics and other carbapenems * Systemic antimicrobial therapy with ceftazidime (internal standard of high-performance liquid chromatography / mass spectrometry) within a 7 days period prior to study entry * Ongoing intraabdominal infections * Terminal illness * Chronic immunosuppressive therapy * Severe diseases of the liver, e.g. cirrhosis of the liver with ALT or AST \> 6 x upper limit of normal (ULN) and bilirubin \> 3 x ULN, severe renal insufficiency with a creatinine clearance ≤30 mL/min., neutrophil count \< 1000 cells/mm3, platelets \< 75000 cells/mm3 and coagulation studies (INR) \> 1.5 x ULN, ongoing therapy with valproin acid.