• The primary endpoint will be percentage failure conditioned by assigned duration of antibiotic therapy (intent to treat analysis). [ Time Frame: 30 days ] [ Designated as safety issue: Yes ]
  

• Failure rate for clinically evaluable patients receiving the appropriate duration of antibiotics [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  
• failure rate for microbiologically evaluable patients [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  
• rate of need for reintervention in the abdomen [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  
• rate of surgical site infection [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  
• rate of death within 30 days [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  
• duration of hospitalization [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  
• rate of intraabdominal or surgical site failure due to antimicrobial-resistant pathogens [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  
• rate of any subsequent infection at a site other than the abdomen or the surgical site [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  
• rate of infection at a non-abdominal, non-surgical site with a resistant organism [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  
• rate of Clostridium difficile infection [ Time Frame: 30 days ] [ Designated as safety issue: No ]
  

Overall, this is a prospective, randomized, single-blinded (analysis), fifteen-center study using intent to treat analysis. Patients will be identified and after informed consent is obtained, will be randomized to receive antibiotics for 3 to 5 days (4 ± 1 days) after the initial surgical or percutaneous intervention or antibiotics until two calendar days after the patient's white blood cell count, systemic temperature, and gastrointestinal function have normalized (maximum of 10 days). The primary endpoint is the composite rate of in-hospital death and/or recurrence of intraabdominal infection and/or occurrence of surgical site (wound) infection. Secondary endpoints include the occurrence of any infection at any site and infection with antibiotic-resistant pathogens. Patient data through the thirty days following the initial intervention or until hospital discharge (whichever is longer) will be tracked

Inclusion Criteria:

• age ≥ 16 at some sites,(≥ 18 at UVA)
• ability to obtain informed consent from the subject or surrogate
• Presence of an intraabdominal infection requiring any duration of hospitalization and managed with open, laparoscopic, or percutaneous intervention.
• A peripheral white blood cell count of > 11,000/mm and/or temperature ≥ 38.0 C with in 24 hours of initial operative or percutaneous intervention.
• Adequate source control in the opinion of the local investigator and PI. Source control is defined as any procedure that stops the ongoing contamination of the peritoneal cavity and removes the majority of the contaminated intraperitoneal contents to the extent that no further acute interventions are felt to be necessary.

Exclusion Criteria:

• age < 16 years at some sites(< 18 at UVA)
• Inability to obtain consent from the patient, parents, or surrogate
• Lack of adequate source control in the opinion of the local investigator or overall PI ( Robert Sawyer)
• High likelihood of death within 72 hours of initial intervention in the opinion of the local investigator or principal investigator
• Lack of any clinical improvement within 72 hours of initial intervention in the opinion of the local investigator or principal investigator.
• Planned relaparotomy
• Perforated gastric ulcer or duodenal ulcer treated within 24hours of the onset of symptoms
• Traumatic injury to the bowel (including iatrogenic or intra-operative) treated within 12 hours of injury
• Non-perforated, non-gangrenous appendicitis or cholecystitis
• Gangrenous appendicitis or peritonitis without confirmatory cultures or with cultures without bacterial or fungal growth
• Ischemic or necrotic intestine without perforation and without positive bacterial or fungal cultures
• Intraabdominal infection associated with active necrotizing pancreatitis
• Primary (spontaneous) bacterial peritonitis
• Intraabdominal infection associated with an indwelling continuous ambulatory peritoneal dialysis catheter.
• Primary skin closure of an open surgical incision in the presence of diffuse, non-localized peritonitis. Laparoscopic port sites ≥ 2cm may be closed
• Pregnancy
• Prior enrollment in this study
• Enrollment in another therapeutic trial