Infectious Colitis

Colonic inflammation due to bacterial, viral, fungal, or parasitic infections

Best imaging tool: CECT with multiplanar reformations

• Mucosal hyperenhancement, marked submucosal edema, ascites

• Multiple air-fluid levels, inflamed pericolonic fat

Ultrasound findings

• Symmetric wall thickening and submucosal echogenicity

• Increased mural flow on color Doppler

Fluoroscopic findings

• Used less frequently than before; now supplanted by CT, US, and endoscopy

Clostridium difficile , Campylobacter , Escherichia coli , CMV

• Accordion sign: Alternating bands of enhancing mucosa and submucosal edema with compressed lumen

May progress to hemorrhagic necrosis and perforation; toxic megacolon

Ulcerative colitis (UC)

• Wall thickening is generally less prominent with UC

Crohn's disease

Ischemic colitis

• Usually located in watershed areas, rarely pancolitis

• Rectum is rarely affected by ischemic colitis

C. difficile colitis occurs mostly in institutionalized patients or those on antibiotic, chemotherapy, or immunosuppressive medication

Acute infectious diarrhea is most often foodborne or waterborne disease

Most common bacterial causes of infectious colitis in USA

• C. difficile , Salmonella , Campylobacter , and E. coli

Symptoms: Watery or bloody diarrhea, fever

• Painful abdominal cramps and tenderness

• Usually acute onset, except TB (chronic)

Diagnosis: Stool cultures, blood cultures, endoscopic biopsy, serology studies

Often self-limited or responsive to antimicrobial therapy in previously healthy patients

Colonic inflammation due to bacterial, viral, fungal, or parasitic infections

Pseudomembranous colitis: Descriptive term usually applied to Clostridium difficile colitis

Best diagnostic clue

• Usually pancolitis, including rectum

Location

• Dependent on etiology

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    C. difficile : Segmental or pancolitis

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      Entire colon usually involved; distal small bowel (SB) uncommonly

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    Campylobacteriosis: Pancolitis ± SB

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    Escherichia  coli (O157:H7): Pancolitis

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    Cytomegalovirus (CMV): Distal ileum and right colon or pancolitis

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    Yersinia enterocolitis: Predominantly right colon, occasionally left; invariably in terminal ileum

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      Right lower quadrant clusters of enlarged nodes

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    Typhoid fever (salmonellosis): Cecum or right colon, invariably in ileum

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    Shigellosis: Predominantly in left colon

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    TB: Right and proximal transverse colon, involves ileum

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    Actinomycosis: Rectosigmoid colon (intrauterine devices), ileocecal region (appendectomy)

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    Gonorrhea, chlamydia, herpes, syphilis: Rectosigmoid colon

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    Histoplasmosis: Ileocecal region

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    Mucormycosis: Right colon

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    Anisakiasis: Occasionally in right colon, rarely in transverse colon

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    Amebiasis: Right colon ± terminal ileum

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    Schistosomiasis: Left or sigmoid colon