<unk>  is caused by the bacterium C.<unk> , a a spore-forming, toxin-producing, obligate anaerobic, gram-positive bacillus. The incidence of<unk>  is estimated to be 140 per 100,000 individuals. In USA, the majority (65%) of cases are associated with healthcare settings, and 25% of cases are associated with previous hospitalizations. The most important risk factor for the development of<unk>  is history of antibiotic use within the past 12 weeks. Other important risk factors include recent hospitalization (< 12 weeks), advanced age (> 65 years), immunodeficiency (primary or secondary causes), inflammatory bowel disease, and exposure to colonized/infected individuals. C.<unk>  spores are transmitted via the fecal-oral route. Following ingestion, spores germinate to the vegetative form in the small intestine and eventually colonize in the large intestine in susceptible patients. C.<unk>  does not result in clinical manifestations in the majority of cases, whereby normal GI flora resists the growth of C.<unk> , and the host immune responses adequately clear the infection before the development of clinical manifestations. However, in susceptible patients, C.<unk>  releases 2 major virulence factors: Exotoxins A and B (TcdA and TcdB), which act synergically and mediate adhesion to the colonic mucosa, luminal fluid accumulation, and development of clinical manifestations. The onset of clinical manifestations may occur within 2 hours up to several months following antibiotic administration. Patients typically develop mild/moderate watery diarrhea (possibly bloody) associated with colicky diffuse abdominal pain, nausea, malaise, and low-grade fever. If left untreated, patients may develop colitis (with or without pseudomembrane formation). Approximately 3% of patients develop complications, which might be colonic (fulminant colitis) or extracolonic. The majority of patients with<unk>  recover without sequelae and are responsive to antimicrobial therapy. Nonetheless,<unk>  is associated with a high lifetime recurrence rate that ranges between 20% to 60%, and most recurrences occur a few weeks following the successful completion of antimicrobial therapy. The gold standard for the diagnosis of<unk>  is cell culture cytotoxic assay, but it is rarely used clinically (difficult technique and time consuming). Among symptomatic patients,<unk>  is diagnosed either by enzyme immunoassay (ELISA) for toxins A and/or B in stools or by DNA-based tests (PCR).<unk>  may be classified based on the clinical severity of the disease. and the severity of the infection dictates the choice of antimicrobial therapy and the need for surgical consultation/management. Administration of oral metronidazole is recommended for patients with mild symptoms, whereas oral vancomycin is recommended for severe disease.
Clostridium difficile infection
Irritable bowel syndrome
Campylobacteriosis
Escherichia coli enteritis
Infectious diarrhea
Allergic colitis
Norovirus infection
Viral gastroenteritis