• Clinical Response in the Microbiologically Evaluable Population [ Time Frame: 10-21 days after the last dose of test article ] [ Designated as safety issue: No ]
• Microbiological Response (Eradication Rate at the Subject Level) [ Time Frame: 10-21 days after the last dose of test article ] [ Designated as safety issue: No ]

• 1. Clinical Response in the microbiologically evaluable population.
• 2. Microbiological Response at the subject and pathogen levels.
• 3. Overall Response defined as a combination of the Clinical Response and the Microbiological Response at the subject level.

This is a phase 3b/4 randomized, open-label, comparative, multicenter study of the safety and efficacy of tigecycline to ceftriaxone sodium plus metronidazole in hospitalized subjects with cIAI (Complicated Intra-Abdominal Infection). Subjects with clinical signs and symptoms of cIAI will be included for enrollment. Subjects will be stratified at randomization for Acute Physiologic and Chronic Health Evaluation scale (APACHE II) score < 10 and > 10. Subjects will be followed for efficacy through the test-of-cure assessment. Safety evaluations will occur through the treatment and post-treatment periods and continue through resolution or stability of the adverse event(s).

• Appendicitis
• Cholecystitis
• Cross Infection
• Diverticulitis
• Peritonitis

• Drug: tigecycline
• Drug: ceftriaxone sodium + metronidazole

Inclusion Criteria:

• Clinical diagnosis of complicated intra-abdominal infection that requires surgery within 24 hours.
• Fever over 100.4°F (38.0°C) or high white blood cell count plus other symptoms such as nausea, vomiting, abdominal pain.

Exclusion Criteria:

• Cancer
• Medicines that suppress the immune system
• Dialysis