Tuberculosis: Symptoms, Causes, Types and Complications

Tuberculosis is an infectious disease caused by Mycobacteria Tuberculosis. It mostly affects the lungs although other organs are involved in 30-35% of cases. It is transmitted by small particle aerosols produced by patients with infectious pulmonary TB. M. Tuberculosis is a rod shaped, non-spore forming and aerobic bacteria which requires acid fast stain for staining. Tuberculosis can be treated with proper pharmacological prophylaxis but if left untreated it can be fatal.

Tuberculosis Symptoms

• Early in the disease process symptoms and signs are non specific consisting mainly of fever, night sweats, anorexia and weight loss. 
• Eventually cough starts developing in most of the cases which can be dry at start but later on it can become productive and sometimes with blood streaks.
• Presence of massive hemoptysis can be a sign of of aspergilloma formation or Rasmussen’s aneurysm( Dilated vessel in cavity).
• Pleuritic chest pain can be seen in patients where disease has spread to pleura( Pleural TB) or parenchyma.
• Any organ system can get infected mainly Lymph node( most common), pleura, Genitourinary system, Bones etc. It is called as Extrapulmonary TB. Nowadays with rise in HIV cases ,Extra pulmonary TB is becoming more prevalent.

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Tuberculosis Causes

The most important cause of Tuberculosis is transmission from a person with infectious pulmonary TB.  It mainly spreads by coughing or sneezing and rarely by ingestion. The tiny droplet nuclei can remain suspended in upper respiratory tract and air for long time. However there are many endogenous factors like immunosuppression, HIV or the patient undergoing cancer treatment play a great role in causation and severity of disease in the patient after exposure. 

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Tuberculosis Risk Factors

There are some factors which determines the acquisition of M.Tuberculosis infection like-

1. Chances of the contact with TB patient
2. Intimacy and Duration of the contact
3. Degree of infectiousness in the patient
4. Crowding in the poorly ventilated rooms increases the chances of infection

However as mentioned earlier the endogenous factors are equally important. Comorbidities which make people susceptible to develop TB are-

• HIV infection
• Silicosis
• Chronic Renal Failure
• Diabetes
• IV drug users
• Immunosuppressive treatment
• Malnutrition/Underweight

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Tuberculosis Types and Complications

• Pulmonary TB (Primary)- It occurs as soon as after exposure but it is asymptomatic most of the times. The lesion( Ghon foci) can develop after initial infection which accompanies hilar lymph nodes with it called as Ghon complex. Ghon foci may or may not be visible on Xray.
• Secondary TB- also called as Reactivation TB, most commonly involves apex of the lung. The effects varies from small infiltrates to extensive cavitary disease.
• Disseminated TB- also called as Miliary TB. It spreads mainly hematogenously and can affect different parts of body like liver.
• Tuberculous Lymphadenitis- Most common presentation of Extrapulmonary TB.
• Pleural TB
• Genitourinary TB/Genital Tuberculosis/Kidney Tuberculosis- Destructive lesions can occur in kidneys and “Thimble bladder “can occur. Genital TB is detected more commonly in females and it can cause infertility and menstrual abnormalities.
• Intestinal Tuberculosis- Tuberculosis can spread to the intestine and it can develop two types of manifestations. Those are- Ulcerative type(mucosal ulcers) and Hyperplastic Ulcers (Extensive Inflammatory changes).
• Skeletal TB/ Pott’s Spine- Mainly due to reactivation of hematogenous foci. The upper thoracic spine is most commonly involved in children however lower thoracic  and upper lumbar vertebrae usually affect the adults.
• Tuberculous Meningitis/Tuberculoma- Presents as one or more space occupying lesions causing seizures and focal signs. Mainly involves children and adults with HIV.

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Tuberculosis Diagnosis

• The suspicion for diagnosis is entertained when patient is having TB like symptoms or chest Xray is showing abnormalities like upper lobe infiltrates with cavitation. The disease is confirmed using AFB smear. NAAT PCR is very last resort to eliminate TB as a possibility.
• To diagnose Pulmonary TB, sputum is used as a specimen. Two sputum samples are taken- Spot sample and Early morning sample. The sample is concentrated using Petroff method( sputum + 4% NaOH).
• Zeil-Neelsen(ZN stain) is used for staining. On microscopy, M. Tuberculosis will be seen as beaded appearance.
• Culture- Lowenstein-Jensen medium 
• Newly automated methods are-
  • Bactec machine( Floresence develops in the presence of bacteria)
  • BacT/alert- Colorimetry based technique
  • Versatrek- detects pressure changes
• Gene xpert- type of CBNAAT. Useful for diagnosis and rifampicin resistance.
• Diagnosis of Latent TB is done using Tuberculin test/ Mantoux test or IGRA.

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Tuberculosis Treatment

• Treatment regimen includes 2 month initial (Intensive) phase of Isoniazid, Rifampin, Pyrazinamide and Ethambutol followed by 4 months of continuation phase of isoniazid and Rifampin.
• Other second line drugs are Amikacin, capreomycin and fluoroquinolones.
• For patients with Isoniazid-Resistant TB, a combination of Rifampin, ethambutol, pyrizinamide and levofloxacin is recommended.
• In HIV patients, the treatment with anti TB drugs  and simultaneous use of ART is associated with significant reductions in mortality risk and AIDS related events. It is very important to note that Rifampin is an enzyme inducer therefore it can lower the efficacy of ART drugs. So Rifabutin is used in place of Rifampin.

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