Infectious colitis


Editorial Board Member: Raul S. Gonzalez, M.D.
Elliot Weisenberg, M.D.

Last author update: 1 November 2016
Last staff update: 10 May 2022

Copyright: 2003-2023,, Inc.

PubMed Search: Tuberculosis[title] colon

Elliot Weisenberg, M.D.
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Cite this page: Weisenberg E. Tuberculosis. website. Accessed April 1st, 2023.
Definition / general
  • Infection of the colon or small intestine by Mycobacterium tuberculosis
  • See Mycobacteria infections other than TB for discussion of the less common M. bovis, M. africanum, M. canetti, M. microti
Essential features
  • Infection occurs by swallowing mycobacteria in sputum (or less commonly infected milk), miliary spread or direct extension from an involved lymph node or the fallopian tube
  • Ileocolonic disease often occurs in the absence of active pulmonary disease
  • Common symptomatology includes weight loss, anorexia, fever, abdominal pain, diarrhea and palpable mass
  • Endoscopic findings include strictures, ulcers and mucosal hypertrophy
  • Biopsies show granulomatous inflammation with confluent granulomas, usually with caseous necrosis
  • Mycobacteria are detected by special stain, culture, nucleic acid amplification or PCR
  • Treatment is with multiple antibiotics and more aggressive treatment is necessary for multidrug resistant and extensively drug resistant TB
  • Surgery may be necessary in the setting of perforation or obstruction
  • Today, colonic TB is uncommon but in the preantibiotic era, 70% of patients who died developed gastrointestinal TB
ICD coding
  • ICD-10: A18.32 - tuberculous enteritis
  • Worldwide (2015): 10.4 million cases of TB and 1.8 million deaths (WHO: Tuberculosis [Accessed 18 October 2021])
  • United States (2015): 9557 cases, rate 3.0 per 100,000 (CDC: Reported Tuberculosis in the United States, 2015 [Accessed 18 October 2021])
  • Approximately 1/3 of world's population has evidence of TB infection
  • Disease of poverty; 95% of cases occur in developing world (61% Asia, 26% Africa)
  • Usually affects young to middle aged adults but all at risk
  • Under 5% of cases of active TB represent intestinal TB
  • Extrapulmonary TB more common in AIDS patients
  • Risk factors: HIV / AIDS, substance abuse, silicosis, diabetes mellitus, chronic kidney disease, malnutrition, organ transplant, head and neck cancer, old age, infancy, immunosuppressive therapy, use of biologic treatments such as infliximab for immune mediated disease
  • Most common in cecum in conjunction with ileum (abundant lymphoid tissue); 70% of patients with gastrointestinal TB have ileocecal disease
  • Also other colorectal sites
  • Multiple sites in 28 - 44%
  • Ileocecum is most common site of abdominal and gastrointestinal TB
  • Isolated colorectal involvement is uncommon - only 10.8% of abdominal gastrointestinal TB
  • Non spore forming, aerobic, nonmotile bacillus with high lipid and mycolic acid content of cell wall
  • Slow growth, generation time 15 - 20 hours
  • Phagocytosed by macrophages, blocks formation of phagolysosome, replication occurs; bacteremia develops (primary TB)
  • Th1 response develops that allows macrophages to contain bacteria
  • Granulomatous inflammation with necrosis and tissue damage occurs
  • Contained infection usually becomes hyalinized and calcified
  • Reactivation may occur with diminished immune status
  • Usually infection is contained, 5 - 10% develop active disease but 30% with HIV
  • Spread to GI tract via swallowed bacteria, hematogenous spread, direct extension from infected lymph nodes or fallopian tube
  • Ileocecum a favored site in GI tract due to abundance of lymphoid tissue
Clinical features
  • Usually chronic disease is present for months
  • Generally weight loss, fever, abdominal pain, diarrhea and often a palpable abdominal mass
  • May see night sweats, anorexia, GI bleeding, malabsorption
  • Perforation or intestinal obstruction may occur

Small intestine
  • Disease occasionally seen in less developed countries
  • Small intestinal disease may be transmitted via contaminated milk
  • Symptoms: abdominal pain, malabsorption, strictures, perforation, fistula
  • Diagnosis may be established by biopsy with demonstration of microorganisms with special stain, culture or molecular techniques
  • Nucleic acid amplification tests and PCR based assays, Xpert MTB / RIF test detects TB and rifampicin resistance, auramine-rhodamine or Ziehl-Neelsen smear of fresh tissue, Ziehl-Neelsen or Kinyoun stain of paraffin embedded tissue, culture (long turnaround time but recommended for confirmation)
  • Detection of antibiotic resistance is important (multidrug resistant or extensively drug resistant TB)
Radiology description
  • Early nodular mucosal thickening with loss of symmetry in the fold pattern
  • May see fissures, sinus tracts, fistulae (rare), ulceration (perpendicular to long axis, cf. Crohn's disease), perforation
  • Obliteration of ileocecal angle with widely patent ileocecal valve
  • Rapid emptying of inflamed terminal ileum (Stierlin sign)
  • Often associated mesenteric lymphadenopathy with increased mesenteric thickness
Prognostic factors
  • Worse prognosis in HIV with low CD4 counts, other immunodepressed states, elderly, debilitated
Case reports
  • Inflammatory cecal masses can mimic acute appendicitis, leading to surgery (World J Emerg Surg 2014;9:7)
  • Generally isoniazid (INH), rifampin, ethambutol (EMB) and pyrazinamide (PZA) for 6 to 9 months (with HIV, use an intensive phase of INH, a rifamycin, PZA and EMB for the first 2 months with continuous INH and a rifamycin for the last 4 months)
  • Drug resistant TB is resistant to at least one first line drug, extensively drug resistant is resistant to INH and rifampin, plus at least one of three injectable second line drugs (amikacin, kanamycin or capreomycin)
  • The CDC recommends expert consultation to treat drug resistant and extensively drug resistant TB
Gross description
  • Ulcerative (most common), hypertrophic and mixed forms are described
  • Usually multiple superficial ulcers perpendicular to long axis of bowel; may see deep ulcers
  • May see thickened mucosal folds, strictures, ulcers, inflammatory nodules; fistulas are rare
Microscopic (histologic) description
  • Caseating granulomas, often confluent and numerous, often cuff of lymphocytes, lymphoid hyperplasia, aphthous to deep ulcers, often architectural distortion
  • AFB stains more likely to be positive in necrotic areas and histiocytes, bacteria may be rare to abundant
  • Hyalinization and calcification with chronicity / treatment
  • Destruction of muscularis propria, scarring
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D. and Elliot Weisenberg, M.D.

H&E: colonic tuberculosis with noncaseating granulomas

Missing Image

Not necessarily colon

Contributed by Hanni Gulwani, M.B.B.S.

Ileocecal tuberculosis in 45 year old woman; epithelioid granulomas with Langhans giant cells in lamina propria

Ileocecal tuberculosis and adjoining draining lymph node

Positive stains

Endoscopy of tuberculosis of ascending colon
Differential diagnosis
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