Tuberculosis is caused by Mycobacterium tuberculosis, a slow-growing, acid-fast bacillus. It spreads by the airborne route: a person with infectious pulmonary or laryngeal TB coughs, sings, or talks and releases tiny droplet nuclei that stay suspended in the air and are inhaled deep into the alveoli. TB is not spread by sharing dishes, touching surfaces, or shaking hands.

Infection vs. disease

About 5–10% of people with TB infection develop TB disease during their lifetime if untreated, with the highest risk in the first 2 years; the risk is much higher with HIV.

Risk factors for progression: HIV infection, diabetes, malnutrition and low body weight, smoking, alcohol use, silicosis, end-stage kidney disease, immunosuppressive drugs (corticosteroids, TNF-alpha inhibitors), organ transplant, young children, and recent infection.

Risk factors for exposure: close contact with someone with infectious TB, birth in or travel to high-burden countries, crowded or congregate settings (prisons, shelters, long-term care), and some health care work.

Extrapulmonary TB can involve lymph nodes, pleura, spine (Pott disease), kidneys, meninges, or be disseminated (miliary TB).

Subjective

• Cough lasting 2–3 weeks or longer, initially dry then productive
• Night sweats, low-grade fever (often in the afternoon or evening), chills
• Unintentional weight loss, anorexia, fatigue
• Hemoptysis, pleuritic chest pain
• Exposure history, prior TB or TB treatment, HIV status, country of birth, living conditions, BCG vaccination history

Objective

• Weight and BMI (wasting)
• Crackles or diminished breath sounds over affected areas (often upper lobes); may be normal
• Signs of extrapulmonary disease: enlarged cervical lymph nodes, back pain, headache with neck stiffness

Interpreting TST induration

A positive TST or IGRA shows infection only; it cannot separate latent infection from active disease. A chest X-ray and symptom review are the next step.

Drug-susceptible pulmonary TB

• Standard 6-month regimen: 2 months of isoniazid (H), rifampin (R), pyrazinamide (Z), and ethambutol (E) (intensive phase), then 4 months of isoniazid and rifampin (continuation phase) — often written 2HRZE/4HR
• 4-month regimen for people 12 years and older weighing at least 40 kg with pulmonary TB: isoniazid, rifapentine, moxifloxacin, and pyrazinamide for 2 months, then isoniazid, rifapentine, and moxifloxacin for 2 months. Not used in pregnancy or breastfeeding, most extrapulmonary TB, or HIV with CD4 below 100 cells/µL (people with HIV need a compatible antiretroviral regimen). Rifapentine is taken with food
• Children with non-severe TB: 4 months of standard drugs
• Directly observed therapy (DOT), in person or by video, supports adherence and prevents resistance
• Pyridoxine (vitamin B6) with isoniazid for those at risk of neuropathy (diabetes, HIV, alcohol use, malnutrition, pregnancy, breastfeeding, kidney failure)

Drug-resistant TB

• Multidrug-resistant TB (MDR-TB) = resistant to at least isoniazid and rifampin
• Current guidance uses 6-month all-oral regimens: BPaLM (bedaquiline, pretomanid, linezolid, moxifloxacin) or BPaL when fluoroquinolone-resistant, for people aged 14 years and older — replacing older 18–24-month injectable-containing regimens
• Requires expert management, drug-susceptibility testing, DOT, and ECG monitoring

TB infection (LTBI) — TB preventive treatment

• Goal: prevent progression to active TB. Rule out TB disease first (symptoms, chest X-ray)
• Preferred short regimens: 3HP (isoniazid + rifapentine once weekly for 12 doses), 4R (daily rifampin for 4 months), or 3HR (daily isoniazid + rifampin for 3 months); 6–9 months of isoniazid is an alternative

Drug safety

Hepatotoxicity rule: stop the drugs and notify the provider if the client has symptoms of hepatitis (nausea, vomiting, abdominal pain, jaundice, dark urine) or marked ALT elevation (commonly > 3 times the upper limit with symptoms or > 5 times without symptoms).

Listed in priority order.

1. Airway and breathing — monitor respiratory status and SpO₂; massive hemoptysis is an emergency (position with the affected side down, suction, call for help)
2. Airborne precautions (prevent transmission)
   • Place the client in an airborne infection isolation room (AIIR) — single room with negative pressure and the door kept closed
   • Everyone entering the room wears a fit-tested N95 (or higher) respirator — for all entries, not only for cough-inducing procedures
   • The client wears a surgical mask (not an N95) when outside the room, such as during transport
   • Teach cough etiquette: cover mouth and nose with a tissue, discard in a closed container, hand hygiene
   • Perform sputum induction and aerosol-generating procedures in an AIIR or booth
3. Specimen collection — early-morning deep-cough sputum in a sterile container, before treatment when possible; 3 specimens 8–24 hours apart
4. Medication administration and adherence
   • Give drugs at the same time daily. Standard first-line drugs are best taken on an empty stomach (with food if GI upset, per prescriber); rifapentine-containing regimens are taken with food
   • Support DOT; explain the reason for each drug and the long duration
   • Monitor for hepatotoxicity, vision changes, neuropathy, gout symptoms
5. Discontinuing isolation (drug-susceptible TB, hospital): the client is on effective standard multidrug therapy, has clinical improvement, and has 3 consecutive negative AFB sputum smears collected 8–24 hours apart, at least one early morning. Clients with MDR-TB often need culture conversion. Home and community isolation decisions follow the health department; U.S. 2024 guidance (National TB Coalition of America) considers most people on effective treatment for at least 5 days low risk and does not rely on smear results alone
6. Nutrition — high-calorie, high-protein diet; weigh weekly
7. Public health — TB is a reportable disease; notify as required so contact investigation can begin
8. Psychosocial support — address stigma, isolation-related anxiety, and financial barriers

• Take every dose for the full course (at least 4–6 months even though symptoms improve in weeks); stopping early causes relapse and drug resistance
• Rifampin turns urine, sweat, and tears orange-red — this is expected; avoid soft contact lenses
• Use nonhormonal contraception while on rifamycins
• Avoid alcohol and acetaminophen overuse; report jaundice, dark urine, abdominal pain, nausea, or vomiting immediately
• Report numbness or tingling (isoniazid), vision changes or trouble telling red from green (ethambutol), and joint pain (pyrazinamide)
• While infectious at home: stay home, sleep in a separate well-ventilated room if possible, avoid visitors (especially young children and immunocompromised people), cover coughs; health departments decide when work or school can resume
• Household and close contacts should be screened and offered preventive treatment when infected
• Eat a nutritious diet; stop smoking; control diabetes
• Keep all follow-up visits, sputum checks, and lab tests

• TB spreads by airborne droplet nuclei → airborne precautions: negative-pressure room, door closed, N95 for everyone who enters, surgical mask on the client during transport
• Latent TB infection = not contagious, no symptoms; treatment prevents progression
• TST: read at 48–72 hours, measure induration; ≥ 5 mm positive for HIV and close contacts
• IGRA preferred after BCG vaccination
• Diagnosis: sputum AFB smear × 3 (one early morning), NAAT, and culture (the standard)
• Standard treatment: 2HRZE/4HR (6 months); a 4-month rifapentine-moxifloxacin regimen is an option at age ≥ 12 years and ≥ 40 kg — not in pregnancy or breastfeeding
• Isoniazid: hepatotoxicity, peripheral neuropathy → pyridoxine (B6)
• Rifampin: orange body fluids, reduces effect of hormonal contraceptives
• Pyrazinamide: hyperuricemia/gout; Ethambutol: optic neuritis, red-green color vision
• Check liver function before and during first-line treatment
• MDR-TB now treated with 6-month all-oral BPaLM/BPaL
• End isolation: effective therapy + clinical improvement + 3 negative smears