Pulmonary tuberculosis


– Pulmonary tuberculosis is a bacterial infection due to Mycobacterium tuberculosis, spread from person to person through inhalation of infected respiratory droplets.
– After infection, M. tuberculosis multiplies slowly in the lungs and is usually eliminated spontaneously or lies dormant.
– Only 10% of cases develop active tuberculosis. The risk of progressing to active tuberculosis is higher in immunocompromised patients. In certain countries, half of newly diagnosed tuberculosis patients are co-infected with HIV
.1

For more information on tuberculosis, refer to the guide Tuberculosis, MSF.

Clinical features

– Prolonged cough (> 2 weeks) with or without sputum production and/or haemoptysis, prolonged fever, night sweats, anorexia, weight loss, chest pain and fatigue.
– Differential diagnosis includes pneumonia, chronic obstructive pulmonary disease (COPD), lung cancer, pulmonary distomatosis (Flukes, Chapter 6) and melioidosis (Southeast Asia).

In an endemic area, the diagnosis of tuberculosis is to be considered, in any patient consulting for respiratory symptoms for over 2 weeks who does not respond to non-specific antibacterial treatment.

Laboratory

– In the general population: Xpert® MTB/RIF test which simultaneously detects M. tuberculosis (MTB) in sputum and resistance to rifampicin (RIF). If not available perform sputum smear microscopy.2
– If HIV co-infection suspected or diagnosed: Xpert® MTB/RIF test and point-of-care, urine LF-LAM (lateral flow urine lipoarabinomannan assay).2

Treatment

For pulmonary tuberculosis, the standard treatment is a combination of four antituberculosis drugs (isoniazid, rifampicin, pyrazinamide, ethambutol). The regimen is organised into 2 phases (initial phase and continuation phase) and lasts 6 months.

If the strain is drug-resistant, the treatment is longer and different drug combinations are used.

It takes significant investment to cure tuberculosis, both from the patient and the medical team. Only uninterrupted treatment will lead to cure and prevent the development of resistance. It is essential that the patient understands the importance of treatment adherence and has access to correct case management until treatment is completed.

Prevention

– BCG vaccination in neonates: provides 59% protection against pulmonary tuberculosis.3
– Infection control in healthcare settings: standard precautions and airborne precautions for confirmed or suspected cases.
– Close contacts: isoniazid preventive therapy for 6 months.



References

  1. World Health Organization. Global tuberculosis report 2018. 
    https://apps.who.int/iris/handle/10665/274453 [Accessed 21 October 2019]

  2. Global Laboratory Initiative. GLI model TB diagnostic algorithms. 2018. 
    http://www.stoptb.org/wg/gli/assets/documents/GLI_algorithms.pdf [Accessed 21 October 2019]

  3. World Health Organization. Weekly epidemiological record/Relevé épidémiologique hebdomadaire 23rd February 2018, 93rd year/23 Février 2018, 93e année. No 8, 2018, 93, 73–96.
    https://www.who.int/immunization/policy/position_papers/bcg/en/ [Accessed 21 October 2019]