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A 75-year-old man with a history of coronary artery disease, hypertension, and diabetes, who underwent a hip replacement 2 weeks ago, presents to the emergency room with several days of diarrhea and 24 hours of increasing abdominal pain and distension. Over the past 3 days he has also had low-grade fevers and general malaise.

On examination he is febrile to 101.7°F and tachycardic. His abdomen is distended and diffusely tender to palpation, with guarding on the right side. His lab work is remarkable for a white blood cell (WBC) count of 21,000/μL and a Cr of 1.6 mg/dL.


Colitis is a general term to describe inflammation of the colon from a variety of causes, including ischemia, infection, and inflammation. Each type of colitis has its own characteristic incidence, presentation, and systemic manifestations.

Ischemic Colitis

The incidence of ischemic colitis in the general population ranges from 4.5 to 44 cases per 100,000 person-years, with a slight predominance in women.1 Despite this low incidence, ischemic colitis is the most common manifestation of mesenteric ischemia, and especially affects the elderly.1

Infectious Colitis

Infectious colitis is caused by a variety of bacterial, viral, and parasitic pathogens. Important pathogens include Salmonella, Shigella, Campylobacter, Enterohemorrhagic Escherichia coli (EHEC), Entamoeba histolytica, Clostridium difficile, and cytomegalovirus (CMV).

C. difficile inhabits the intestinal tract of 1% to 3% of healthy adults and 20% of patients receiving antibiotics, but only a subset of these patients develop C. difficile colitis.2 Despite this, the clinical impact of C. difficile colitis cannot be underestimated. According to data from the United States Healthcare Cost and Utilization Project’s Nationwide Inpatient Sample, from 2000 to 2009 the incidence of C. difficile infection increased from 49.2 to 109.6 per 100,000 population.3 In 2009, an estimated 336,600 hospitalizations, nearly 1% of all hospital stays, were due to C. difficile colitis. The majority of patients affected were 60 to 70 years old, and in patients with a principal diagnosis of C. difficile colitis, the colectomy rate was 1.6%.4

Infection with cytomegalovirus (CMV), a member of the herpesvirus family, is very common throughout the world. Seroprevalence increases with age. In a US-based study among individuals aged 6 to 49 years, CMV seroprevalence increased from 38% in 6- to 11-year-olds to 58% in those aged 40 to 49 years.5 CMV seropositivity was independently associated with older age, female sex, foreign birthplace, low household income, high household crowding, and low household education.5 Initial infection in an immunocompetent host may go unnoticed, but patients who are immunocompromised by treatment with immunosuppressive medications or by illnesses that reduce cellular immunity, such as inflammatory bowel disease or human immunodeficiency virus (HIV) infection, are susceptible to CMV systemic disease including retinitis, pneumonia, encephalitis, ...

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