Pathogenesis and treatment of intra-abdominal infection. Intra-abdominal infection is considered potentially life-threatening. Such infection is frequently secondary to perforated viscera, trauma or inflammatory disease. Simple abscesses may be drained percutaneously with roentgenologic guidance; complex abscesses often require open surgical drainage. Secondary peritonitis is usually polymicrobial; broad-spectrum antimicrobial therapy effective against aerobic and anaerobic gram-negative bacteria, as well as gram-positive organisms, is essential. Newer antibiotics, administered either singly or in combination, have been used successfully to treat intra-abdominal infection while avoiding the toxicity of aminoglycosides. 