| Popis: |
This chapter discusses two enterotoxin-producing clostridia that rank among the most important enteric pathogens of humans, Clostridium difficile and enterotoxin-positive type A strains of C. perfringens. The major lethal toxins (LTs) are not the only biomedically important C. perfringens toxins; some C. perfringens isolates, mostly belonging to type A, express C. perfringens enterotoxin (CPE). Recognized outbreaks of C. perfringens type A food poisoning are usually very large, averaging about 100 cases. C. perfringens type A food poisoning is acquired by ingestion of a food item containing vegetative cells of a CPE-positive C. perfringens type A strain. C. perfringens isolates associated with non-food-borne human gastrointestinal (GI) disease consistently carry a plasmid-borne cpe gene, which distinguishes them from food poisoning isolates carrying a chromosomal cpe gene. C. difficile is an opportunistic pathogen that causes nosocomial diarrhea and colitis after the normal GI flora has been altered, most typically by antibiotics. C. difficile-mediated disease develops from the production of two toxins, toxin A and toxin B, which in some papers are referred to as the enterotoxin and cytotoxin, respectively. Toxin production occurs during the stationary phase, under conditions that limit the growth of the organism. Certain basic precautions should be taken to help control outbreaks of C. difficile disease. In most instances, the incidence of disease can be reduced simply by educating health care workers about the disease and how it is spread. |
