Pulmonary Tuberculosis

Introduction

Tuberculosis (TB) is one of the oldest diseases known to affect humans. It is caused by bacteria of mycotuberculosis complex which includes M. tuberculosis, M. bovis, and M. africanum.
M. tuberculosis is the most common cause of tuberclosis worldwide.
Transmission is by droplet infection.
Almost every organ can be affected. The lung parenchyma are affected in more than 80% of the cases. This can be either as primary pulmonary disease (occurs mainly in childhood) or post primary pulmonary disease.
Those at risk of acquiring tuberculosis are:

  • Contacts of patients with smear positive pulmonary disease
  • Immunocompromised individuals,
    health works and people living in
    overcrowded conditions.

Clinical Features

Common symptoms of pulmonary
tuberculosis:

  • Persistent cough
  • Weight loss
  • Drenching night sweats
  • Chest pain (dull or pleuritic)
  • Haemoptysis
  • Anorexia

Signs:

  • Physical examination may be normal
  • Crepitations usually in the upper zone (earliest physical sign)
  • Physical signs of consolidation, cavitation and fibrosis develop later

Other signs:

  • palor and finger clubbing,
  • Erythema nodusum and phlynctenular
  • conjuctivitis (Primary PTB)

Differential Diagnosis

  • Pneumonia
  • Carcinoma of the bronchus
  • Lung abscess (especially due to Klebsiella pnenmoniae)
  • Pulmonary infarction

Complications

  • Lung collapse
  • Bronchiectasis
  • Chronic Obstructive Pulmonary Disease
    Pleural effusion
  • Corpulmonale
    • Destructive lung syndrome
    • Lung abscess
  • Acute Respiratory Distress Syndrome
  • Spontaneous Pneumothorax
  • Haemorrhage/Mycetoma

Extrapulmonary TB:

Lymph node TB:

  • Painless swelling of lymph nodes (usually cervical and supracervical sites
  • Usually discrete in early disease; may become inflamed and have a fistulous tract draining caseous material)

Pleural TB:

  • Fever
  • Pleuritic chest pain
  • Dyspnoea
  • Dullness to percussion
  • Absence of breath sounds
  • TB of the upper airways:
    • Nearly always a complication of advanced cavitatory pulmonary TB
    • May involve the laynx, pharynx and epiglottis:
  • Hoarseness
  • Dysphagia
  • Dysphonia
  • Chronic productive cough

Genitourinary TB:

  • Urinary frequency
  • Dysuria
  • Haematuria
  • Flank pain

Skeletal TB:

  • Weight bearing joints are affected: spine, hips and knees

Spinal TB (Pott’s disease):

  • Paraparesis
  • Paraplegia

TB meningitis:

  • Headache
  • Mental changes
  • Confusion
  • Lethargy
  • Altered sensorium
  • Neck rigidity
  • Ocular nerve paresis
  • Hydrocephalus

Gastrointestinal TB:

  • Commonly affects the terminal ileum and caecum
  • Abdominal pain (may be similar to that of appendicitis)
  • Diarrhoea
  • Intestinal obstruction.
  • Haematochezia
  • Palpable mass Fever
  • Weight loss
  • Night sweats
  • – TB peritonitis

Pericardial TB:

  • Fever
  • Dull retrosternal pain
  • Friction rub
  • Cardiac tamponade

Military TB:

  • Fever
  • Night sweats
  • Anorexia
  • Weakness
  • Weight loss
  • Cough
  • Hepatomegaly
  • Splenomegaly
  • Lymphadenopathy
  • Choroidal tubercles (pathognomonic)
  • Meningitis

There are no clinical findings specific for a diagnosis of pulmonary TB; a history of contact with a smear positive pulmonary TB case, respiratory symptoms for more than 2-3 weeks not responding to broad spectrum antibiotics, and weight loss, failure to thrive may suggest TB.

Relevant Investigations

Bacteriologic examination:

  • Sputum AFB X 3 (spot, morning, spot)
  • Sputum mycobacterial culture and
    drug susceptibility testing/Gene xpert
  • Xpert MTB-RIF Assay

Radiologic Examination

  • Chest X-ray

Other tests:

  • Tuberculin skin test (low sensitivity and low specificity)
  • Hematologic –  Full blood count & ESR

In cases of diagnostic difficulties, one mayneed High Resolution CT and fibre-optic brouchoscopy with bronchoalveolar levage and trans-bronchial biopsy

Treatment objectives

  • Cure the disease
  • Prevent death from active TB or its late effects
  • Decrease transmission of TB
  • Prevent the development of acquired drug
  • Prevent relapse of TB

Chemotherapy

Standard drug regimens for Adults

A. 6 months regimen

Initial Intensive Phase:

  • This is for 2 months using Rifampicin, Isoniazid, Pyrazinamide and Ethambutol.

Continuation Phase:

  • 4 months using Isoniazid and Rifampicin.
  • In this regimen, there is fully supervised administration of
    drugs in both intensive and continuation phases.

Daily doses and adverse reactions of commonly used anti-tuberculosis drugs (Adults)

  • Pyridoxine 10 mg are usually added to prevent peripheral neuropathy
  • These drugs can be provided as fixed dose combinations to enhance adherence to therapy or loose tablets.

Other aspects of management include:

  • Contact tracing
  • Health education of the patient

Standard drug regimens for Children

Two standardized treatment Regimen adopted for the treatment of all children. diagnosed with susceptible TB (refer to your national guidelines on this as there might be countries variations)
1. Standard six month treatment
Regimen for all children with newly diagnosed or previously treated PTB disease.
Regimen 1 for Children:
2(RHZ+E)/4(RH)
2. Standard six month treatment
Regimen for all children with newly diagnosed or previously treated EPTB disease.
Regimen 2 for children with EPTB:
2(RHZ+E)/10(RH)
Tb Paediatric drugs and dosages

Use of Pyridoxine (Vitamin B6) in children

  • Pyridoxine (vitamin B6) protects against isoniazid-induced peripheral neuropathy.
  • It is not routinely given but is recommended for severely malnourished and HIV-infected children
  • The recommended dose is 25 mg/ day until treatment is completed

Monitoring of PTB Treatment

Monitoring for response to therapy (clinical improvement and bacteriologic clearance in sputum) and adverse drug reactions.
Routine laboratory monitoring for drug
toxicity may not be necessary when there are no symptoms, signs or co-morbid factors like hepatic and renal disease.

Multidrug Resistance Tuberculosis (MDR-TB)

  • Drug resistance in mycobacteria comes about through random spontaneous mutation.
  • Emergence of this is creating additional barriers to effective tuberculosis control.
  • MDR-TB is caused by an organism resistance to at least isoniazid and rifampicin.
  • Extensively drug-resistant TB  (XDR-TB) is MDR-TB plus resistance to any of the floroquinolones and one of the second line injectables.

MDR-TB Suspects

  • Failure of treatment with first line anti tuberculosis drugs
  • Symptomatic contacts to a known MDR TB case

Diagnosis

  • Send sputum samples to specialized facility for culture, molecular line probe and drug susceptibility

Treatment

Refer to designated treatment centres

HIV Associated Pulmonary Tuberculosis

  • Tuberculosis is an important opportunistic among HIV infected persons and commonest cause of death in such patients.
  • It directly attacks the critical immune mechanism involved in protection against Tuberculosis.
  • Its presentation depends on the stage of HIV infection.
  • Diagnosis of tuberculosis in HIV patients may be difficult when the immunity is highly compromised (low CD4 count) because of atypical presentation, increase frequency of sputum smear negativity and atypical radiographic features.
  • All TB patients should be offered HIV counselling and testing; also all HIV patients should be screened for TB.

Treatment:

  • Commence anti-tuberculosis treatment.
  • Offer Co-trimoxazole preventive therapy
  • Commence anti-retroviral therapy
  • First line Anti-tuberculosis drugs though very effective but the problems in the treatment of such patients are:
  • Pill burden
  • Drug interaction

Drug interactions

  • There is potentials for drug interactions with rifampicin and antiretroviral agents such as protease inhibitors (PIs) and non nucleoside reverse transcriptase inhibitor (NNRTIs).
  • Rifabutin may be used in place of rifampicin but not easily available and expensive.
  • Efavirenz may be used in place of nevirapine
  • Immune reconstitution syndrome
  • Increased incidence of drug resistance cases