Host-parasite interaction in serious infections due to gram-negative bacteria

Gram-negative rods such as Enterobacteriaceae and Pseudomonadaceae are normal habitants of the digestive tract. However, if defense mechanisms of the host are compromised by underlying diseases such as malignant neoplasms, renal insufficiency, extensive traumata, or immunosuppressive therapy, invasion of the blood-stream can occur. Gram-negative septicaemia is associated with high morbidity and mortality, despite intensive care and administration of potent antibiotics. A central role in the pathophysiology of life-threatening bacteriaemia is attributed to endotoxin, a constituent of the gram-negative cell wall. This paper reviews current concepts of septic shock, the acquisition of gram-negative bacteraemia and the role of endotoxin. It also deals with a new approach to prevention and control of severe gram-negative infections using serotherapy based on the structure of endotoxin.