Tuberculosis and the GI tract - Gastrointestinal infections

Tuberculosis and the GI tract

Definition

Infection of the gastrointestinal tract or the peritoneum by Mycobacterium tuberculosis.

Aetiology/pathophysiology

Infections are most common in the immunosuppressed and are more common due to HIV. Sources of gastroin-testinal tuberculous infections:

·        Reactivation of primary tuberculosis.

·        Bovine TB infections from unpasteurised milk.

·        Self-infection may occur due to swallowing of infected sputum.

Intestinal tuberculosis occurs at any point of turbulence, e.g. the oesophagus at the indentation of the aorta, the pylorus and the ileocaecal valve, which is most commonly affected. Caseating granulomas and fibrosis may result in stricture formation and obstructions. Tuberculous peritonitis may result from reactivation of TB within an abdominal lymph node.

Clinical features

The presentation depends on the site of infection and often has an insidious onset. Patients may present with diarrhoea, abdominal pain, alteration of bowel habit, blood in stool and systemic features of anorexia and weight loss. Gastric outflow obstruction may result in vomiting and a succussion splash on examination. There may be a palpable abdominal mass. Clinically gastroin-testinal tuberculosis may be difficult to distinguish from Crohn’s disease.

Investigations

Abdominal ultrasound may demonstrate mesenteric thickening and lymph node enlargement. In patients with vomiting an upper gastrointestinal endoscopy is performed. Diagnosis may be made using histology, culture or PCR of tissue obtained at laparoscopy or colonoscopy (particularly from the ileocaecal valve and terminal ileum). See also Tuberculosis (page 102).

Management

Treatment with a combination of rifampicin, isoniazid, pyrazinamide and ethambutol if resistance is likely. Therapy should continue for 1 year in gut infections and 2 years in peritonitis. Surgical resection of a strictured bowel may be required for obstruction and to exclude a caecal carcinoma.