Intra-abdominal infections are common in clinical practice and comprise a wide variety of clinical presentations and differing sources of infection. A cIAI extends beyond the hollow viscus of origin into the peritoneal space and is associated with either abscess formation or peritonitis (Solomkin et al. 2010). Different bacterial pathogens are responsible for cIAIs, including gram-negative aerobic bacteria, gram-positive bacteria, and anaerobic bacteria, and there are also mixed infections. Uncomplicated intra-abdominal infections and complicated intra-abdominal infections may be difficult to distinguish, but in general cIAIs extend beyond local viscera into peritoneal or retroperitoneal spaces and are associated with systemic signs and symptoms of illness. When patients are diagnosed with cIAI, antibacterial drug therapy is recommended before, during, and after the planned surgical procedure (e.g., open laparotomy, laparoscopy, percutaneous drainage of an abscess).