Clostridia and Bacteroides in Enteric Infections

Abstract

The ability of anaerobic bacteria to cause disease in humans and animals has been recognized for many years. The clostridia, for example, are well known for their ability to cause disease by producing a variety of toxins ranging from the potent neurotoxins of Clostridium tetani and Clostridium botulinum to the tissue-damaging toxins of the gas gangrene clostridia. Bacteroides fragilis, on the other hand, represents the major anaerobic pathogen in clinical specimens from patients with abscesses and soft-tissue infections. More recently, the importance of members of these genera in gastrointestinal infections has become recognized. Clostridium difficile has emerged as the major cause of nosocomial diarrhea because of its ability to produce diarrhea and pseudomembranous colitis in patients treated with antibiotics. Clostridium perfringens, which is the major cause of gas gangrene, produces a diverse group of toxins that are involved in enteric disease. In industrialized countries, outbreaks of C. perfringens food poisoning occur because of the production of a spore-associated enterotoxin. In certain regions in the Pacific rim, especially in Papua New Guinea, a disease known as pigbel, which is prevalent in persons who eat improperly cooked pork, results from infection with C. perfringens type C strains that produce β-toxin. In addition to these maladies, type E strains of C. perfringens and certain strains of Clostridium spiroforme produce a toxin (iota) that results in another distinctive type of enterotoxemia in animals.