Immune response to Clostridium difficile infection.

Clostridium difficile produces two toxins (A and B) which cause antibiotic-associated diarrhoea and pseudomembranous colitis. One of the most puzzling aspects of C. difficile infection is the wide spectrum of clinical presentation which ranges from asymptomatic carriage to fulminant, life-threatening colitis. This review examines the hypothesis that immune responses to C. difficile underlie these dramatic variations in disease presentation and course. Animals can be protected from C. difficile colitis by passive or active immunization against toxins A and B. Human antibody responses to these toxins are evident in approximately 60% of the general population. A number of clinical studies indicate that antitoxin responses in both serum and intestinal secretions may be protective whereas an inadequate immune response predisposes to severe or recurrent C. difficile diarrhoea. Thus there is now considerable interest in developing methods for passive and active immunization to combat this prevalent nosocomial intestinal pathogen.