The main objective is to study the efficacy of topical antibiotic therapy with Amoxicillin / Clavulanic acid in the prevention of surgical wound infection in patients undergoing to colorectal surgery

Is a clinical trial phase IV prospective, blind, controlled and random allocation of treatment with the active principle of amoxicillin 1000mg and 200mg Clavulanic acid, administered topically and dissolved in 500 ml of saline 0.9%. To demonstrate its effectiveness in the surgical wound infection prophylaxis be used in contaminated surgery and be compared its effectiveness with the topical administration of normal saline only.

Inclusion Criteria:

• Patients over 18 years of age.
• Patients who require urgent surgical intervention and who come from the emergency service
• Patients affected by complicated intra-abdominal infection with peritonitis of more than one abdominal compartment or intra-abdominal abscess requiring open surgical intervention.

Exclusion Criteria:

• Women patients with positive pregnancy test.
• Patients with primary peritonitis and liver cirrhosis.
• Patients who have received antibiotic treatment during the 72 hours prior to the surgical intervention (except that administered to UCIES as a treatment dose of the same process)
• Patients allergic to the antibiotic used in the study.
• Patients who have undergone a surgical procedure of recently opened abdomen (up to 30 days before surgery), a prosthesis of synthetic material (mesh) or to which the surgical wound can not be closed according to the surgeon's criteria.
• Patients with an unfavorable life prognosis (ASA 5).

In the operating room area we will keep a notebook with the random number sheet and a box with the numbered envelopes and containing the treatment to follow: physiological saline alone or physiological saline with antibiotic. At the end of the surgery and before closing the abdominal wall, it is definitively informed to the nurse whether or not to recruit them, a case number is assigned chronologically and in the random number sheet corresponds to an envelope containing one of the two treatments. Dilution is performed with 10cc of physiological saline solution with or without antibiotic in the outside of the operating room and then it is incorporated into the 500cc bottle of physiological saline once opened in a sterile way. We used according to the usual protocol.