Tuberculosis (TB)

Tuberculosis is a chronic granulomatous disease caused by Mycobacterium Tuberculosis. It's transmitted via droplets. It progresses in 3 stages:

• Primary TB - In 90%, the immune system contains the infection as macrophages engulf the bacteria and localize them to the hilar lymph nodes. At this point, they’re removed or encapsulated by granulation tissue (caseous necrosis).

• Secondary TB - Some progress to active TB, with an increased risk in the immunosuppressed (e.g. HIV). This usually occurs at the apex of the lungs.

• Miliary TB - Some aren’t able to contain the primary infection, and it disseminates widely via the blood. Looks like hundreds of millet seeds on a CXR.

Risk factors for it include:

• Close contact to infected person

• Living in or immigrants from areas of high TB prevalence e.g. sub-saharan africa and south asia

• Young or elderly

• Immunosuppression e.g. HIV, Medications

• Homelessness, Drug-use, Alcohol abuse

Patients typically present with:

• Chronic productive cough +/- haemoptysis

• Weight loss

• Night sweats

• Fever

Investigations

The main investigation to do is a CXR, which will show:

• Active - Patchy consolidations, Pleural effusions, Hilar lymphadenopathy

• Secondary - Patchy/Nodular consolidations w/cavity formation

• Milliary - Millet-seed lesions spread through lung fields

Other investigations to do include:

• Sputum MC&S - staining with Ziehl-Neelsen stain (turns bright red)

• Mantoux test (injection of tuberculin) - looks for previous immune response to TB

Management

RIPE:

• Rifampicin for 6 months. SE of Red/Orange urine and tears.

• Isoniazid for 6 months. SE of Peripheral neuropathy due to inhibition of vit B6. Pyridoxine (Vit B6) given to prevent this.

• Pyrazinamide for 2 months. SE of Hyperuricaemia (Gout).

• Ethambutol for 2 months. SE of Eye disturbance (Optic neuritis)

N.B. At 2 months, PEe the rest away aka. stop Pyrazinamide and Ethambutol.