Intra-abdominal sepsis: a medical-surgical dilemma.

Much progress has been made in our understanding of the pathophysiology of intra-abdominal infection over the past 100 years. By 1900, investigators had evidence of both an aerobic and an anaerobic component in these infections. By the 1970s, the role of gram-negative aerobic organisms in peritonitis and the role of anaerobes in abscess formation were emerging. Improved culture techniques have demonstrated the true polymicrobial nature of intra-abdominal infection. In our most recent study, an average of 3.9 isolates per patient was cultured. Because of the mixed flora present in these infections, antibiotic regimens must be active against both aerobes and anaerobes. This coverage has usually been accomplished with combinations of antibiotics, although some newer, single-agent regimens may also be effective. Even with our increased knowledge, intra-abdominal infection followed by sepsis remains the most common cause of death among patients in the intensive care unit. Mortality is associated with multiple, recurrent, or persisting abscess; positive blood cultures; and organ failure. Surgery, if indicated, should be undertaken before the onset of significant organ failure. Reducing the mortality from organ failure will depend more on the ability to modulate the metabolic and immune pathways that lead to sepsis than on the development of broader-spectrum antibiotics and more aggressive surgical algorithms.