What is Gastrointestinal Tuberculosis?
Gastrointestinal tuberculosis, also known as GI TB, is a type of tuberculosis that affects the digestive system. It makes up 1% to 3% of all tuberculosis cases globally. Although it can occur alongside active lung disease, it can also take place as a primary infection without affecting the lungs. This type of tuberculosis most commonly affects the ileocecal region (where the small and large intestines meet), but it could affect any part of the digestive tract.
Recognizing this disease can be difficult because its symptoms are not always obvious or specific. The good news is that GI TB generally responds well to standard tuberculosis drugs. Surgery is usually only needed if the illness causes complications like strictures (narrowing of the intestines) or blockages which don’t improve with medications.
Early detection and treatment significantly reduce the impact of the disease, so high clinical suspicion is essential. An interprofessional team of healthcare professionals plays a key role in treating this condition quickly and effectively to lessen risk and improve patient recovery.
What Causes Gastrointestinal Tuberculosis?
The gastrointestinal tract (GIT), which includes the stomach and intestines, can be infected by a type of bacteria known as mycobacteria in five different ways:
1. When a person with a type of lung disease caused by Mycobacterium tuberculosis swallows their own sputum or phlegm.
2. The bacteria can travel through the bloodstream from another infected part of the body.
3. The bacteria can spread through the lymphatic system, which is part of your immune system, from infected lymph nodes.
4. Infection can extend directly from a site next to the GIT.
5. Infection can occur from eating dairy products, particularly raw milk, infected with Mycobacterium bovis.
Doctors have divided abdominal tuberculosis (a type of GIT infection) into two categories: a primary form caused by direct consumption of Mycobacterium bovis, and a secondary form caused by the spread of bacteria from lung disease.
The last part of the small intestine (ileum) and the ileocaecal valve (a valve that connects the small and large intestines) are commonly affected by GIT infection. This is because of several factors: these parts have a narrow passage, the food stays there longer (allowing the bacteria to be absorbed), they don’t have much digestion activity, and they contain special cells in their immune tissue that can capture bacteria.
Mycobacteria have a fatty outer shell that makes them hard to digest, which means they aren’t usually released in the earlier parts of the GIT. Therefore, it was once thought that it was rare for the bacteria to affect the parts of the GIT nearer to the stomach. However, it’s now known that they can also infect these areas.
Risk Factors and Frequency for Gastrointestinal Tuberculosis
Gastrointestinal tuberculosis (GI TB) is a type of tuberculosis that does not affect the lungs and accounts for around 12% of all tuberculosis cases. Specifically, GI tuberculosis represents 11% to 16% of these cases, which equate to about 1% to 3% of all tuberculosis cases. People with intra-abdominal TB, a subset of GI TB, often also have pulmonary TB (TB in the lungs), with reported rates ranging from 6% to 38%. However, whether or not they have active pulmonary TB can vary based on the criteria used in different studies.
There is conflicting information on whether GI TB is more common in males or females. Some studies suggest it is more common in females, while others find there is no difference between sexes. Cultural and ethnic factors in different communities may result in varying exposure levels, which can cause a difference in the occurrence of the disease.
The relationship between the age of a patient and the incidence of GI TB is unclear. Some research suggests that middle-aged people are most commonly affected, while other studies indicate a higher incidence in people under 25. Some studies reported an equal distribution among age groups, which might be due to a high prevalence of close family intermarriages, leading to an overall reduced immune response across ages.
It has been observed that GI TB is more common in populations with lower socioeconomic status, with factors such as illiteracy and malnutrition possibly contributing to this. It can also be seen in people with HIV/AIDS. In fact, tuberculosis co-infections are the most common cause of death in patients with HIV/AIDS.
In developed countries, TB is commonly associated with people who have HIV/AIDS or have immigrated from developing countries. Interestingly, GI TB has been diagnosed in patients who had migrated many years prior. However, GI tuberculosis is overall less common and prevalent in developed countries compared to developing countries.
In both developing and developed countries, cases of GI TB have been observed in patients who are receiving anti-TNF-alpha treatments and patients who have had various solid-organ transplants, including kidney, kidney-pancreas, liver, and heart. However, despite these associations, the incidence of GI TB in transplant patients remains low overall. Worryingly, cases of GI TB have also been reported in people with normal immune systems.
Signs and Symptoms of Gastrointestinal Tuberculosis
People with gastrointestinal tuberculosis, also known as GI TB, often experience a variety of symptoms. However, it’s important to note that some individuals may not show any symptoms of the condition. Common complaints include:
- Abdominal pain
- Loss of appetite
- Fever
- Changes in bowel habits, with diarrhea being more common than constipation
- Nausea and vomiting
- Passing of black, tarry stools (known as melena)
During a medical check-up, the doctor might notice several signs of GI TB, which may include:
- Weight loss
- Pale skin and anemia
- Rectal bleeding
- Swollen and bloated abdomen (due to fluid build-up, also known as ascites)
- An enlarged liver (hepatomegaly)
- An enlarged spleen (splenomegaly)
- Swollen lymph nodes (lymphadenopathy)
- Abdominal mass
It’s essential to remember that not all patients with GI TB may have a family history of TB. Therefore, physicians should consider the possibility of this condition even when there’s no family history. Additionally, only a small number of patients might have been affected by pulmonary TB in the past or have it alongside GI TB.
Testing for Gastrointestinal Tuberculosis
In simpler terms, if a doctor is worried a patient may have gastrointestinal tuberculosis, a few tests are usually conducted. Tests often include checking the amount of hemoglobin and a type of protein called serum albumin in the blood, as well as running a C-reactive protein (CRP) test. Hemoglobin is a protein inside your red blood cells that carries oxygen, and serum albumin helps to keep fluid from leaking out of blood vessels. The CRP test is a general test to look for inflammation or infection in the body. In this case, if all three results suggest lower hemoglobin and serum albumin levels but a high CRP, the patient may have gastrointestinal tuberculosis.
Different tests help in recognizing TB, including an acid-fast stain, culture tests, nucleic acid amplification tests, and a standard interferon-gamma release assay or Quantiferon test. However, all these tests tend to give poor results when it comes to diagnosing this disease, due to its nature. A newer method called polymerase chain reaction (PCR) test has been found useful. It helps identify TB genes in samples but it’s not perfect, as it can’t tell the difference between living and dead TB bacteria.
Imaging techniques, like a CT scan, can also be useful for checking the extent of the disease. It can help to identify features like unusual wall thickening of the intestine and any changes in solid organs. Another process, known as CT enterography, is gaining attention as it can be used to assess the healing of TB lesions non-invasively. Ultrasound tests are helpful in diagnosing solid-organ lesions while other specialized instruments like colonoscopy can aid in detecting asymptomatic cases and taking tissue samples that could clarify the diagnosis.
Finally, a therapeutic trial is an approach used when tests don’t provide a clear result but the patient’s signs and symptoms suggest that it could be TB. Treating the patient with tuberculosis medicines and watching if they improve often helps doctors to establish a diagnosis.
Treatment Options for Gastrointestinal Tuberculosis
The recommended treatment for intra-abdominal or gastrointestinal tuberculosis is a four-drug combination of isoniazid, rifampicin, pyrazinamide, and ethambutol. These drugs are generally taken three times a week for the first two months, and then just isoniazid and rifampin are taken for another four months. This therapy is often very successful, with evidence of healing from ulcers as early as two months into treatment.
Typically, the recommended duration of this treatment is six months. This timeframe has been validated by multiple studies, and has the benefits of being more cost-effective and seeing greater patient compliance when compared to longer treatment durations. However, if the infection has spread throughout the body, longer treatment might be necessary. Therefore, each patient should be evaluated individually and specialist medical advice should be considered.
Healing as a result of therapy is recognized by the recovery of the mucous tissue in the intestines. However, there might be persistent issues such as narrow passages, polyps, and enlarged tissue lesions. It is also observed that these narrow passages may occur more frequently in patients who have received this therapy before. Additionally, blockages in the gut may worsen due to healing and scar formation.
One common side effect of this therapy is liver injury, which is the most common cause of stopping the therapy. This is especially seen among patients who have Hepatitis B and C along with tuberculosis.
An endoscopy procedure, in which a flexible tube with a light and camera is inserted into the gastrointestinal tract, can do balloon dilation to help manage narrow passages in the small intestine and duodenum, the first part of the small intestine.
For complications such as obstruction, perforation, and abnormal connection between two body parts (fistulas), surgery might be needed. Surgical options fall into three main categories:
- Bypassing the affected sections of the bowel, although these procedures are not commonly done as they can be complicated and could continue the disease in the remaining sections.
- Removal of the affected segments, used when there is a bowel perforation caused by tuberculosis. Despite the effectiveness of this method, most patients are not in good health and may have difficulty recovering from the operation.
- More conservative surgeries, such as repairing the narrow passage, when it’s causing more than 50% blockage. Surgery might be needed for patients who still have narrow passages even after therapy, as well as those with multiple narrow passages that are less likely to respond to therapy.
What else can Gastrointestinal Tuberculosis be?
Tuberculosis of the gastrointestinal tract, also known as “the great mimicker,” can often appear similar to other diseases. This includes conditions such as:
- Esophageal cancer
- Esophageal ulcers and tumors
- Stomach ulcers and cancer
- Colorectal cancer and sarcomas
- Acute infections like appendicitis, inflamed colon (colitis), inflamed gallbladder (cholecystitis), and a severe skin infection called necrotizing fasciitis.
- Sarcoidosis which is a disease involving abnormal collections of inflammatory cells that form lumps known as granulomas.
These conditions could show changes in imaging tests like PET scans or CT scans and could even show increased tumor markers.
It’s also common for this type of tuberculosis to get mistaken for Crohn’s disease. In fact, such misdiagnoses can happen in up to 70% of cases. There have also been instances where patients with Crohn’s disease showed positive stains for Acid-Fast Bacilli (AFB), a test often used to detect tuberculosis.
To differentiate between gastrointestinal TB and Crohn’s disease, doctors can look for various features. TB patients may commonly have symptoms such as fever, night sweats, lung involvement, and fluid accumulation in the abdomen. Diarrhea, blood in stool, surrounding skin diseases, and extraintestinal symptoms are more common in Crohn’s disease.
Endoscopy can also provide distinct signs. TB tends to show circular or transverse ulcers surrounded by inflamed tissue, caseating granulomas, and abnormalities in the ileocecal valve. Crohn’s disease, on the other hand, more commonly presents longitudinal ulcers, aphthous ulcers, a “cobblestone” appearance, strictures in the lumen, mucosal bridges, skip areas of healthy tissue and diseased tissue, and involvement of the rectum and sigmoid colon. Isolated issues in the duodenum and jejunum are normally seen in Crohn’s disease rather than TB.
Distinct changes in blood tests may also help to tell these two conditions apart. Patients with gastrointestinal TB usually have lower hemoglobin, lower serum albumin, and high C-reactive protein levels. To specifically identify TB, a PCR test can be run on tissue samples. This test is high in specificity for intestinal TB. However, an older test that uses anti-Saccharomyces cerevisiae antibodies may not be as reliable to differentiate these two diseases.
Several prediction models have been developed to distinguish the two diseases. However, these models do have certain limitations like application to a larger population and complex calculations. Some researchers also suggest that giving a therapeutic trial to patients (like treating them with antitubercular therapy and seeing if they improve) could help to tell the two diseases apart. However, how long the therapeutic trial should last is still yet to be determined.
What to expect with Gastrointestinal Tuberculosis
If abdominal or gastrointestinal tuberculosis is not treated, it can have a mortality rate, or death rate, between 6% and 20%. This means that out of 100 people with this condition who don’t receive treatment, between 6 and 20 people may die. Furthermore, untreated abdominal tuberculosis can lead to complications that might require surgery.
Possible Complications When Diagnosed with Gastrointestinal Tuberculosis
Several complications can arise from gastrointestinal tuberculosis. These complications include:
- Upper and lower gastrointestinal bleeding
- Fistulas forming at various locations
- Blockage of the gut
- Narrowing of the gut due to scar tissue
- Intussusception, where a part of the intestine telescopes into itself
- Perforation of the gut
- Anemia
- Problems related to nutrition like weight loss, mal-absorption of nutrients, and lack of essential vitamins and minerals
- Chronic inflammatory demyelinating polyneuropathy (a rare neurological disorder) was reported in one case
Intestinal tuberculosis is often confused with Crohn’s disease. This misdiagnosis and the subsequent treatment with medicines meant to suppress the immune system, unfortunately, can lead to harmful outcomes. In some cases, intestinal tuberculosis can happen as a complication of treating Crohn’s disease using medicines that suppress the immune system. These patients might have an increased severity of pre-existing Crohn’s disease or even the start of new lesions if these treatments are stopped.
Just like other types of tuberculosis, the emergence of the antibiotic-resistant version of tuberculosis (or MDR-TB) in the abdomen is a concern. A Taiwanese study reported the presence of MDR-TB in 13% of patients with gastrointestinal TB. A large chunk of these patients also had lung TB.
Preventing Gastrointestinal Tuberculosis
Gastrointestinal tuberculosis, a type of tuberculosis that affects the digestive system, can be difficult to diagnose. This is because the symptoms and imaging results usually don’t point to a specific disease. Unfortunately, this often leads to a delayed diagnosis, which can cause various complications.
However, if doctors are alert and suspect this condition, they can use different tests and studies to help identify it earlier. This can lower the risk of serious health problems and death related to the disease. The main treatment for gastrointestinal tuberculosis is medication designed to fight tuberculosis. Only a small number of cases require surgery as part of their treatment plan.
