Clinical features and diagnosis of Tuberculosis

Tuberculosis (TB) is a bacterial infection caused by Mycobacterium tuberculosis.

Get the full solved assignment PDF of MME-105/As-1 of 2024 session now.

It primarily affects the lungs but can also involve other organs such as the brain, spine, kidneys, and bones. The clinical features and diagnosis of TB depend on the site of infection and the individual’s immune status. Here’s an overview:

**Clinical Features:**

1. **Pulmonary TB**:

   – Chronic cough lasting more than 3 weeks

   – Hemoptysis (coughing up blood)

   – Chest pain

   – Fatigue

   – Fever, chills, and night sweats

   – Loss of appetite and weight loss

   – Breathlessness and difficulty breathing

2. **Extra-pulmonary TB**:

   – Symptoms vary depending on the affected organ system:

     – **Central Nervous System**: Headache, neck stiffness, confusion, focal neurological deficits

     – **Skeletal TB**: Back pain, spinal deformity, joint pain, swelling

     – **Abdominal TB**: Abdominal pain, distension, diarrhea, gastrointestinal bleeding

     – **Genitourinary TB**: Dysuria, flank pain, hematuria, infertility

     – **Disseminated TB**: Fever, weight loss, generalized weakness, lymphadenopathy, hepatosplenomegaly

**Diagnosis:**

1. **Medical History and Physical Examination**: Obtain a detailed medical history, including symptoms suggestive of TB, history of exposure to TB patients, travel history, and risk factors such as HIV infection or immunosuppressive therapy. Perform a thorough physical examination to assess for signs of TB and associated complications.

• **Tuberculin Skin Test (TST)** or **Interferon-Gamma Release Assay (IGRA)**: These tests detect immune response to TB infection. TST involves injecting purified protein derivative (PPD) tuberculin into the skin and assessing for a delayed hypersensitivity reaction. IGRA measures interferon-gamma released by T cells in response to TB antigens.

• **Chest X-ray**: A chest X-ray is commonly used to evaluate for pulmonary TB and may show abnormalities such as infiltrates, cavitations, or pleural effusions. However, chest X-ray findings are not specific for TB and may overlap with other pulmonary conditions.

• **Sputum Smear Microscopy**: Microscopic examination of sputum samples for acid-fast bacilli (AFB) using Ziehl-Neelsen staining is a rapid and inexpensive method for diagnosing pulmonary TB. However, it has limited sensitivity, especially in paucibacillary or extra-pulmonary TB.

• **Sputum Culture**: Culture of Mycobacterium tuberculosis from sputum samples is the gold standard for TB diagnosis. It provides definitive identification and allows for drug susceptibility testing to guide treatment.

• **Molecular Testing**: Nucleic acid amplification tests (NAATs), such as the Xpert MTB/RIF assay, can rapidly detect TB and rifampicin resistance directly from sputum samples. These tests offer high sensitivity and specificity and are particularly useful in diagnosing drug-resistant TB.

• **Biopsy and Histopathology**: In cases of extra-pulmonary TB or suspected drug-resistant TB, tissue biopsy (e.g., lymph node, bone, or organ biopsy) may be performed to obtain specimens for histopathological examination and culture.

• **Other Investigations**: Depending on the clinical presentation and suspected site of infection, additional investigations such as imaging studies (CT scan, MRI), lumbar puncture, urine analysis, or serological tests may be indicated to evaluate for TB involvement of specific organ systems.

Early diagnosis and prompt initiation of treatment are essential for controlling TB transmission, preventing complications, and improving patient outcomes. Treatment typically involves a combination of antibiotics (e.g., isoniazid, rifampicin, pyrazinamide, ethambutol) administered over several months, tailored to the type and severity of TB infection. Directly Observed Therapy (DOT) is recommended to ensure treatment adherence and reduce the risk of drug resistance.