Gastrointestinal Tuberculosis - An Overview

Introduction

Although tuberculosis (TB) is mainly an infection of the lungs (pulmonary TB), it can affect any organ other than the lungs and is known as extrapulmonary tuberculosis. One of the most common extrapulmonary TB manifestations that can defy diagnosis is gastrointestinal TB. Gastrointestinal tuberculosis makes up approximately one percent to three percent of all TB cases worldwide. There needs to be greater awareness of this condition due to symptoms that overlap with other gastrointestinal disorders and the low diagnostic test accuracy. If left untreated, gastrointestinal TB can result in severe morbidity that requires extended hospital stays and surgery. Gastrointestinal TB can affect many sections of the GI system, such as the esophagus, stomach, small and large intestines, rectum, and anus.

What Causes Gastrointestinal Tuberculosis?

Mycobacterium tuberculosis is the causative agent of gastrointestinal tuberculosis. The GIT (gastrointestinal tract) can become infected with mycobacteria in five different ways:

• Direct contact with respiratory secretions of an infected person.

• Individuals with active tuberculosis in their lungs can swallow infected phlegm or sputum, resulting in GIT (gastrointestinal tract) infection.

• Mycobacteria can enter the bloodstream from distant infections and reach GIT.

• The bacteria may spread to GIT through the infected lymph nodes.

• Consuming milk products contaminated with Mycobacterium bovis, a related bacteria that may infect cows, can result in gastrointestinal tuberculosis.

Who Gets Gastrointestinal Tuberculosis?

Gastrointestinal tuberculosis is a relatively uncommon infection, affecting around one to three percent of all TB cases. Due to compromised immune systems or increased exposure to bacteria, some individuals are more likely to develop GITB:

• Individuals With Extrapulmonary Tuberculosis: GI TB accounts for around 11 percent to 16 percent of all cases of extra-pulmonary tuberculosis.

• Gender: Some research has reported a high prevalence of GI TB in females, while other studies have reported equal predisposition in both sexes.

• Age: The relationship between GI TB and a patient's age is unclear. According to one study, people in their middle years (the reproductive age group) are most frequently impacted. In other studies, younger patients (under 25) had a higher incidence. Additionally, some studies show an equal age distribution.

• Socio-Economic Status: Lower socio-economic groups are more likely to have GI TB, and factors including hunger and illiteracy may also contribute.

• Immune Status: It is also observed in cases of acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection. Patients on anti-tumor necrosis factor-alpha (anti-TNF-alpha) medications and those who have received solid organ transplants after kidney, kidney-pancreas, liver, and heart transplants have also been linked to gastrointestinal tuberculosis (GI TB).

What Are the Symptoms of Gastrointestinal Tuberculosis?

Gastrointestinal TB may cause symptoms similar to other GI disorders, including Crohn's or cancer. The ileocecal region (the last segment of the small intestine, the ileum, and the first section of the large intestine, the cecum) is the most commonly affected GI tract.

The most common symptoms include:

• Abdominal pain.

• Weight loss.

• Fever.

• Altered bowel habits, with diarrhea being more common than constipation.

• Nausea.

• Vomiting.

• Melena (dark stools).

• Paleness.

• Anemia.

• Rectal bleeding.

• Abdominal distension (swelling in belly area) and ascites (abdominal swelling due to fluid accumulation).

• Hepatomegaly (enlarged liver).

• Splenomegaly (enlarged spleen).

• Lymphadenopathy (enlarged lymph nodes).

• Abdominal mass.

What Are the Complications of Gastrointestinal Tuberculosis?

Possible complications of gastrointestinal TB are:

• Upper and lower gastrointestinal bleeding.

• Fistula (when part of the GI system becomes connected where it should not).

• Obstruction of the gut.

• Stricture (narrowed intestines).

• Intussusception (a segment of the intestine folds like a telescope, resulting in an intestinal blockage)

• Perforation (hole).

• Anemia.

• Malnutrition and malabsorption.

• Weight loss.

• Deficiency of essential vitamins and minerals.

• One case showed chronic inflammatory demyelinating polyneuropathy (a condition characterized by nerve inflammation, which results in a loss of strength or sensation).

How Is Gastrointestinal Tuberculosis Diagnosed?

Diagnosing GITB is difficult because of its nonspecific symptoms and the need to distinguish it from other illnesses.

• A thorough clinical evaluation is needed to look for the signs and symptoms.

• Blood tests are done to look for lower hemoglobin levels, serum albumin, and high C-reactive protein (CRP) levels.

• Mycobacterium-specific tests such as adenosine deaminase (ADA) and polymerase chain reaction (PCR) testing are less reliable because they target the bacteria that cause TB. Still, GITB usually has a low bacterial count.

• Imaging tests include computed tomography (CT) scans and ultrasound.

• Asymptomatic patients with GI TB may undergo a colonoscopy. Biopsies obtained during the procedure provide high diagnostic accuracy.

What Is the Treatment of Gastrointestinal Tuberculosis?

1. Anti-Tuberculosis Therapy: This is the first line of treatment with four medications.

• Isoniazid.

• Rifampicin.

• Pyrazinamide.

• Ethambutol.

2. Duration of Treatment: These four drugs are taken thrice weekly for the first two months. Then, for the next four months, only Isoniazid and Rifampicin are taken. The total treatment duration typically lasts for six months. This treatment is very effective and gives good results. While six months of treatment is common, some patients with widespread TB may need a longer duration.

3. Endoscopic Intervention: In some cases, an endoscopic balloon dilation procedure is performed to treat gastrointestinal tuberculosis complications such as strictures (narrowed sections) in the small intestine.

4. Surgical Therapy: Most cases of GI TB are treated with anti-tuberculosis therapy. However, surgery might be needed to create complications like bowel obstruction, perforation (hole), and fistula (abnormal connection).

Surgical options are divided into three major general categories:

• Bypassing of Involved Bowel Segments: This involves creating alternative routes for the passage of waste to bypass the damaged part of the intestine. These procedures are not commonly performed since they are sometimes complicated by blind loop syndrome, fistula formation, and recurring illness in the remaining segments.

• Radical Resection of Involved Segments: This involves removing a portion of the severely damaged intestine, combined with anti-tuberculous therapy to eliminate the TB bacteria. However, most patients need more nourishment, making them poor surgical candidates.

• Strictureplasty: This is done in cases where narrowing of the intestine is present. It involves widening the narrowed segment of the intestines without removing it.

Conclusion

Mycobacterium tuberculosis is the causative agent of gastrointestinal tuberculosis. It may produce symptoms similar to those of other gastrointestinal disorders. Antimicrobial therapy is the cornerstone of treatment for intestinal tuberculosis, but endoscopic and surgical procedures are also frequently needed. Early diagnosis and treatment are essential for complete recovery. One must seek medical attention if experiencing any GI-related symptoms.