Pulmonary Tuberculosis

BY: MOHAMED HUSSEIN

Cause Caused by Mycobacterium tuberculosis (M. tuberculosis)

Gram (+) rod (bacilli). Acid-fast

Pulmonary TB occurs in the lungs 85% of all TB cases are pulmonary

Extrapulmonary TB occurs in places other than the lungs, including the: Larynx Lymph nodes Brain and spine Kidneys Bones and joints

Miliary TB occurs when tubercle bacilli enter the bloodstream and are carried to all parts of the body

Transmission Spread person to person through airborne particles that contain M. tuberculosis

Transmission occurs when an infectious person coughs, sneezes, laughs, or sings

Prolonged contact needed for transmission

10% of infected persons will develop TB disease at some point in their lives 5% within 1-2 years 5% at some point in their lives

Reactivation due to immune suppression

Infects 1/3rd of the world’s population

Chance of death: 4%

2nd most common cause of death from an infectious disease in the world. Causing 1.2-145 million deaths a year

Pulmonary Tuberculosis Primary pulmonary TB (primary exposure) is characterized by the Ghon

complex and consists of 1.) subpleural (fissure) focus of inflammation. 2.) Infected (inflamed) lymph nodes draining the primary, subpleural lesion. A Ghon focus is a primary lesion usually subpleural, often in the mid to lower zones

Secondary pulmonary TB (reactivation) is characterized by a focus of infection and granuloma formation usually in the apex of the lung. The small granulomas (tubercles) eventually coalesce to form larger areas of consolidation with central caseating necrosis. Regional lymph nodes contain caseating granulomas.

Progressive pulmonary TB: Primary or secondary TB may go on to heal. Caseating granulomas are replaced by fibrosis and calcification. Cases that don’t heal spontaneously or with drug therapy can progress to form cavities or spread to other parts of the lung and to other organs through lymphatic channels and bloodstream. Milliary tuberculosis.

Necrotizing Granuloma

Miliary Spread

Ghon Complex

Risk Factors

HIV30% develop active disease.

Disease of poverty: Linked to malnutrition and overcrowding.

Drugs: Injection

Prisons, homeless centers

High risk ethnic minorities, healthcare workers

Smoking, diabetes mellitus, alcoholism

Signs/Symptoms Productive prolonged cough*

Chest pain

Hemoptysis

Fever and chills

Night sweats

Fatigue

Loss of appetite

Weight loss

Diagnosis

Medical history Physical examination Mantoux tuberculin skin test Chest x-ray: Consolidation or cavitation in lung apices.

Sputum Collection: essential to confirm TB Culture: 2-8 week Smear, PCR

Treatment Latent infection:

Daily Isoniazid therapy for 9 months Monitor patients for signs and symptoms of hepatitis and peripheral neuropathy

Alternate regimen – Rifampin for 4 months

TB Disease: Regimen of 3-4 drugs 1st-line drugs for 6 months. Isoniazid (INH) Rifampin (RIF) Pyrazinamide (PZA) Ethambutol (EMB)

Recurrent Disease: Test for antibiotic susceptibility and if MDR-TB, treat with at least 4 effective antibiotics for 18-24 months.

Primary vs Secondary resistance

Prevention: BCG vaccine for children

Case

A 23-year-old man presented with a 4-week history of coughing, breathlessness and malaise. He had lost 4kg in weight, but had no history of night sweats or haemoptysis. He had returned from holiday in Pakistan 2 months earlier. On examination, he was mildly pyrexial (37.8°C) but had no evidence of anaemia or clubbing. Crepitations were audible over the lung apices; there were no other physical signs. The chest X-ray showed bilateral upper- and middle-lobe shadowing but no hilar enlargement. Sputum was found to contain acid-fast bacilli and Mycobacterium tuberculosis was subsequently cultured. A Mantoux test was strongly positive. A diagnosis of pulmonary tuberculosis was made. The patient was treated with isoniazid and rifampicin for 6 months, together with pyrazinamide for the first 2 months. He was allowed home on chemotherapy when his sputum became negative on direct smear. The chest X-ray is now much improved.

References 1. http://radiopaedia.org/cases/pulmonary-tuberculosis

2. http://library.med.utah.edu/WebPath/LUNGHTML/LUNG033.html

3. http://www.pathpedia.com/education/eatlas/imagepedia/pulmonary_tuberculosis-necrotizing_granuloma.aspx