Pulmonary tuberculosis


Pulmonary tuberculosis is a bacterial infection due to Mycobacterium tuberculosis, spread by airborne route. After contamination, M. tuberculosis multiplies slowly in the lungs: this represents the primary infection.
In immunocompetent patients, the pulmonary lesion heals in 90% of cases, but in 10%, patients develop active tuberculosis.
Tuberculosis may also be extrapulmonary: tuberculous meningitis, disseminated tuberculosis, lymph node tuberculosis, spinal tuberculosis, etc.

Patients with HIV infection have an increased risk of developing active tuberculosis. Tuberculosis is the opportunistic disease that most commonly reveals AIDS. In certain countries, up to 70% of patients with tuberculosis are co-infected with HIV.

Clinical features

Prolonged cough (> 2 weeks), sputum production, chest pain, weight loss, anorexia, fatigue, moderate fever, and night sweats.
The most characteristic sign is haemoptysis (blood in sputum), however it is not always present and haemoptysis is not always due to tuberculosis. If sputum is smear-negative, consider pulmonary distomatosis (Flukes, Chapter 6), melioidosis (Southeast Asia), profound mycosis or bronchial carcinoma.

In an endemic area, the diagnosis of tuberculosis is to be considered, in practice, for all patients consulting for respiratory symptoms for over two weeks who do not respond to non-specific antibacterial treatment.

Diagnosis

– Sputum smear microscopy; culture.
– Chest X-rays are useful for the diagnosis of smear negative tuberculosis and tuberculosis in children.

Treatment

The treatment is a combination of several of the following antituberculous drugs [isoniazid (H), rifampicin (R), pyrazinamide (Z), ethambutol (E), streptomycin (S)]. The regimen is standardised and organized into 2 phases (initial phase and continuation phase).
The treatment of drug-sensitive tuberculosis lasts a minimum of 6 months.

It takes significant investment to cure a tuberculous patient, both from the patient and the medical team. Only uninterrupted treatment for several months may lead to cure and prevent the development of resistance, which complicates later treatment. It is essential that the patient understands the importance of treatment adherence and that he has access to correct case management until treatment is completed.

Prevention

When BCG is correctly carried out, it confers protection that is not insignificant (probably over 50%). It has been proven that BCG protects against severe forms of the disease, in particular tuberculous meningitis and miliary tuberculosis.

BCG vaccination does not diminish transmission of tuberculosis.


For more information on the diagnosis, treatment and prevention of tuberculosis, and on the follow-up of tuberculosis patients, refer to the guide Tuberculosis, MSF