Tuberculosis

What is tuberculosis (TB)?

A chronic infectious disease caused by Mycobacterium tuberculosis, transmitted via airborne droplets and capable of causing pulmonary and extrapulmonary disease.

What are major risk factors for tuberculosis?

• Crowded living conditions (urban, prisons, nursing homes)

• Immunosuppression/HIV

• Diabetes mellitus

• ESRD

• IVDU

• Alcohol use

• Homelessness

What are classic symptoms of pulmonary TB?

• Fever

• Chronic cough

• Night sweats

• Hemoptysis

• Weight loss

• Lymphadenopathy

• Cachexia

What physical exam findings may be seen in pulmonary TB?

• Rales in the apical lungs

• Fever

• Cachexia

• Signs of extrapulmonary involvement depend on organ system

What extrapulmonary manifestations can occur in TB?

• CNS (HA, AMS)

• Lymphatic LAD

• Skeletal back pain/arthritis

• Renal hematuria/dysuria

• Ocular uveitis/chorioretinitis

• Cutaneous granulomas

• Pericarditis (chest pain)

What chest X‑ray findings are associated with TB?

• Unilateral apical infiltrates

• Cavitations

• Caseating granulomas

• Ghon complex (primary lesion)

• Ranke complex (calcified Ghon lesion + lymph node)

• Pleural effusions

What is a Ghon complex?

A calcified primary TB lesion in the lung parenchyma, often with associated lymph node involvement.

What is a Ranke complex?

A healed, calcified Ghon lesion plus calcified hilar lymph nodes.

What diagnostic tests confirm active TB?

• Sputum PCR

• Mycobacterial culture (gold standard)

• AFB smear

What is the most sensitive test for TB?

Mycobacterial culture, though the results take weeks.

What is the fastest confirmatory test for TB?

PCR testing.

What is the purpose of an AFB smear?

Rapid detection of acid‑fast bacilli

What screening tests are used for latent TB?

• Interferon‑Gamma Release Assay (IGRA)

• PPD (tuberculin skin test)

What PPD induration is considered positive at ≥5 mm?

• HIV+

• Close contacts of active TB

• Abnormal CXR consistent with prior TB

What PPD induration is considered positive at ≥10 mm?

• Recent immigrants

• IV drug users

• Nursing home residents

• Prisoners

• Medical risk factors

• High‑risk populations

What PPD induration is considered positive at ≥15 mm?

General population with no risk factors.

What factors can cause false‑negative PPD results?

• Immunosuppression

• Recent TB infection

• Very young or elderly

• Overwhelming active TB

What factors can cause false‑positive PPD results?

BCG vaccination or infection with non‑tuberculous mycobacteria.

What PFT pattern is seen in TB?

Not typically used for diagnosis

What are the treatment goals for TB?

Eradicate infection, prevent transmission, and prevent drug resistance.

What is the treatment for latent TB infection?

Rifapentine + isoniazid weekly for 3 months (3HP regimen).

What is the treatment for active TB?

RIMP regimen: rifapentine, isoniazid, moxifloxacin, pyrazinamide for 8 weeks, then RIM for 9 more weeks.

What medications are included in standard TB therapy?

• Rifamycins (rifampin/rifapentine)

• Isoniazid

• Pyrazinamide

• Ethambutol or moxifloxacin

What are major side effects of isoniazid?

Hepatotoxicity and peripheral neuropathy (prevented with pyridoxine/B6).

What are major side effects of rifampin/rifapentine?

Orange body fluids, hepatotoxicity, drug interactions.

What are major side effects of pyrazinamide?

Hyperuricemia and hepatotoxicity.

What are major side effects of ethambutol?

Optic neuritis (red‑green color blindness).

What infection control measures are required for active TB?

Airborne isolation, N95 masks, negative‑pressure room.

What complications can occur from TB?

• Miliary TB

• Pott's disease (vertebral TB)

• Pleural effusion

• Pericarditis

• Meningitis

• Respiratory failure

What is miliary TB?

Disseminated TB with tiny millet‑seed‑like lesions throughout the lungs and other organs.

What is Pott disease?

TB infection of the spine, causing vertebral destruction and back pain.

What is the prognosis of untreated active TB?

Progressive disease with high morbidity and mortality.

What symptoms suggest extrapulmonary TB?

• Back pain

• Headache/AMS

• Flank pain/hematuria

• Joint pain

• Ocular inflammation

• Pericarditis

What is the hallmark symptom triad of pulmonary TB?

Fever, night sweats, weight loss.

What is the most common site of reactivation TB?

Apical/posterior upper lobes due to high oxygen tension.

What is the mechanism of TB transmission?

Airborne droplet nuclei that remain suspended in air for prolonged periods.

What is the role of IGRA testing?

Preferred in BCG‑vaccinated individuals

What finding on CXR suggests reactivation TB?

Cavitary lesions in the upper lobes.

What is the significance of caseating granulomas?

Classic histologic hallmark of TB infection.

What is the role of directly observed therapy (DOT)?

Ensures adherence and prevents drug resistance.

What is the most important public health measure for TB control?

Early detection and treatment of active cases.