Evaluation of Safety,Pharmacokinetics and Efficacy of CAZ-AVI With Metronidazole in Children Aged 3 Months to 18 Years Old With Complicated Intra-abdominal Infections (cIAIs).

Inclusion Criteria

• Must be ≥3 calendar months to 38.5°C, or equivalent to method used) or hypothermia (with a core body or rectal temperature 15000 cells/mm3) C-reactive protein (CRP) levels (>10 mg/L)
• Physical Findings consistent with intra-abdominal infection, such as:

Abdominal pain and/or tenderness Localised or diffuse abdominal wall rigidity Abdominal mass

• Intention to send specimens from the surgical intervention for culture
• (Optional) Supportive radiologic findings of intra-abdominal infection, such as perforated intraperitoneal abscess detected on: Computed tomography (CT) scan or Magnetic resonance imaging (MRI) or Ultrasound (ii) Intra-operative/postoperative enrolment inclusion(in cases of postoperative enrolment, must be within 24 hours after the time of incision)::

Visual confirmation of intra-abdominal infection associated with peritonitis at laparotomy, laparoscopy or percutaneous drainage (to be confirmed pending feasibility); must have 1 of these diagnoses:

• Appendiceal perforation or peri-appendiceal abscess
• Cholecystitis with gangrenous rupture or perforation or progression of the infection beyond the gallbladder wall
• Acute gastric or duodenal perforations, only if operated on >24 hours after singular perforation occurs
• Traumatic perforation of the intestines, only if operated on >12 hours after perforation occurs
• Secondary peritonitis (but not spontaneous bacterial peritonitis associated with cirrhosis and chronic ascites)

Exclusion Criteria

• Involvement in the planning and/or conduct of the study (applies to both AstraZeneca staff and/or staff at the study site)
• Previous enrolment or randomisation in the present study
• Participation in another clinical study with an investigational product (IP) during the last 30 days before the first dose of IV study drug or have previously participated in the current study or in another study of CAZ-AVI (in which an active agent was received)
• History of hypersensitivity reactions to carbapenems, cephalosporins, penicillin, other β lactam antibiotics metronidazole or to nitroimidazole derivatives
• Concurrent infection, that may interfere with the evaluation of response to the study antibiotics at the time of randomisation
• Patient needs effective concomitant systemic antibacterials (oral, IV, or intramuscular) in addition to those designated in the 2 study groups (CAZ-AVI plus metronidazole group or meropenem group) (see Section 7.8)
• Receipt of non-study systemic antibacterial drug therapy for cIAI for a continuous duration of more than 24 hours during the 72 hours preceding the first dose of IV drug, except in proven resistant organisms and/or worsening of the clinical condition for more than 24 hours. More than 2 consecutive doses are not permitted if the individual doses are expected to give >12 hours' cover (ie, giving a total cover of >24 hours.) For patients enrolled after a surgical procedure, only 1 dose of non study antibiotics is permitted postoperatively
• Patient is considered unlikely to survive the 6 to 8 week study period
• Patient is unlikely to respond to 7 to 15 days of treatment with antibiotics
• Patient is receiving haemodialysis or peritoneal dialysis
• Diagnosis of abdominal wall abscess confined to musculature of the abdominal wall or ischaemic bowel disease without perforation, traumatic bowel perforation requiring surgery within 12 hours of perforation, or perforation of gastroduodenal ulcers requiring surgery within 24 hours of perforation (these are considered situations of peritoneal soiling before the infection has become established)
• Simple (uncomplicated), non-perforated appendicitis or gangrenous appendicitis without rupture into the peritoneal cavity identified during a surgical procedure OR presence of primary peritonitis (ie, spontaneous bacterial peritonitis) or peritonitis associated with cirrhosis or chronic ascites
• At the time of randomisation, patient is known to hav