OVERVIEW

What is Tuberculosis?

Tuberculosis (TB) is an infectious disease caused by *Mycobacterium tuberculosis*. The most common form is pulmonary TB, but other organs can also be infected. After infection, individuals have a 5%–10% lifetime risk of developing active TB.

*Mycobacterium tuberculosis* is a slender, acid-fast bacterium with stronger pathogenicity and higher infectivity than ordinary bacteria. Its acid-fast property—resisting decolorization by ethanol after staining—is used to detect the bacteria in sputum samples from TB patients.

What is Congenital Tuberculosis?

Congenital TB is not a genetic disease but rather an infection acquired by the fetus in utero. It is diagnosed at birth, in newborns (within 28 days), or infants (within 3 months) and is also called intrauterine TB.

What is Drug-Resistant Tuberculosis?

Drug-resistant TB occurs when *Mycobacterium tuberculosis* becomes resistant to one or more first-line anti-TB drugs. These drugs include isoniazid, rifampin, pyrazinamide, ethambutol, and streptomycin.

Based on resistance patterns, drug-resistant TB is classified into:

• Mono-resistant TB: Resistance to only one anti-TB drug. In the late 1940s, scientists discovered that TB bacteria could develop resistance—patients treated solely with streptomycin initially improved but later relapsed due to resistance. This led to the current multi-drug treatment approach.
• Poly-resistant TB: Resistance to more than one anti-TB drug (e.g., isoniazid or rifampin, but not both).
• Multidrug-resistant TB (MDR-TB): Resistance to at least isoniazid and rifampin, possibly with additional resistance.
• Extensively drug-resistant TB (XDR-TB): Resistance to isoniazid, rifampin, fluoroquinolones, and at least one injectable second-line drug (e.g., amikacin, kanamycin, or capreomycin).
• Totally drug-resistant TB (TDR-TB): Resistance to all tested drugs, though some may respond to less common agents (e.g., cycloserine, terizidone, clofazimine, linezolid, or carbapenems).

By timing of resistance, it can also be categorized as:

• Primary resistance: Occurs in untreated patients.
• Acquired resistance: Develops after prior effective TB treatment.

Is Drug-Resistant TB Common?

Yes, and it’s increasing.

The WHO 2016 Global TB Report estimated that ~4% of new TB cases and 21% of previously treated cases worldwide were MDR-TB. China, India, Russia, and former Soviet states have the highest burdens.

Only half of MDR-TB patients achieve cure, highlighting poor treatment outcomes.

SYMPTOMS

Which parts of the body are most susceptible to tuberculosis?

Mycobacterium tuberculosis primarily infects the respiratory tract, causing pulmonary tuberculosis, which accounts for about 85% of all TB cases. It can also spread to other organs through the lymphatic system or bloodstream, collectively referred to as extrapulmonary tuberculosis, making up approximately 15% of cases.

The most common form of extrapulmonary TB is lymph node tuberculosis. Other types include tuberculous meningitis, tuberculous peritonitis, renal tuberculosis, intestinal tuberculosis, epididymal tuberculosis, female genital tuberculosis, and bone tuberculosis.

What are the common symptoms of tuberculosis?

Early-stage TB may have mild or no symptoms, but without control, symptoms gradually worsen. Common symptoms include:

• Fatigue: Persistent tiredness even without physical exertion, not relieved by rest, often accompanied by poor appetite and sleep disturbances.

• Low-grade fever: Afternoon fever, typically between 37.5–38°C.

• Night sweats: Excessive sweating during sleep.

• Cough with sputum: Common, usually producing white, sticky mucus.

• Hemoptysis: Coughing up blood from the respiratory tract below the larynx.

• Chest pain, shortness of breath, irregular menstruation, difficulty breathing, etc.

What are the dangers of tuberculosis?

Tuberculosis primarily harms the respiratory system, causing cough, hemoptysis, and chest pain. Extensive lesions may lead to difficulty breathing. Severe cases (e.g., miliary TB, extensive cavitary TB, or advanced extrapulmonary TB) can be life-threatening if untreated.

Additionally, TB can damage other organs. Without proper treatment, it may become chronic, recurrent, or drug-resistant, rendering medications ineffective and turning patients into persistent sources of infection for others.

CAUSES

Which populations are more susceptible to tuberculosis?

The onset of tuberculosis refers to the condition where Mycobacterium tuberculosis, after infecting a person, is not controlled or eliminated, leading to common clinical symptoms of tuberculosis and confirmed diagnosis through examination.

There are three age groups most susceptible to Mycobacterium tuberculosis infection: under 1 year old, adolescence, and the elderly. Currently, tuberculosis in China is more prevalent among young and middle-aged adults.

How is tuberculosis transmitted?

Mycobacterium tuberculosis is more resistant than ordinary bacteria. It can survive for 6–8 months in sputum in dark conditions and 8–10 days in dust. Under direct sunlight, it can be killed in 2 hours, and under UV light within 1 meter, it can be killed in 10–20 minutes.

When tuberculosis patients are in the infectious phase, they spread the bacteria into the air through coughing or sneezing. Healthy individuals become infected by inhaling droplets containing the bacteria. Tuberculosis bacteria surviving in dust may also enter the respiratory tract through the air, potentially causing infection.

How can tuberculosis be transmitted?

Primary transmission routes:

• Airborne transmission: Tuberculosis patients in the infectious phase spread the bacteria into the air through coughing or sneezing, and healthy individuals become infected by inhaling the droplets.
• Dust transmission: When tuberculosis patients in the infectious phase spit phlegm on the ground, it evaporates and becomes dust carrying the bacteria, infecting healthy people.
• Aerosol transmission: Tuberculosis bacteria scattered on the ground, bedding, or other objects are inhaled into the alveoli of healthy individuals.

Secondary transmission routes (less common):

• Oral transmission: Consuming food or drink containing large amounts of tuberculosis bacteria.
• Skin transmission: Tuberculosis from other parts of the body spreads through skin lesions.
• Intrauterine transmission: A mother with tuberculosis infects her fetus.

How does tuberculosis develop?

Only a small proportion of people infected with Mycobacterium tuberculosis develop the disease. Whether tuberculosis occurs depends on two factors:

• The virulence of the bacteria and the immune resistance of the infected person. Tuberculosis develops when the bacteria are highly virulent and the infected person has low resistance.
• The lifetime risk of developing tuberculosis after infection is about 5%–10%, with most cases occurring within 2–4 years of infection.

Therefore, uninfected individuals should avoid exposure, while infected individuals should strengthen their immunity to minimize the risk of developing tuberculosis.

Under what conditions are tuberculosis patients prone to drug resistance?

The following conditions increase the likelihood of developing drug-resistant tuberculosis:

• Previous history of anti-tuberculosis treatment;
• Current anti-tuberculosis treatment is irregular or not followed as prescribed (e.g., arbitrarily reducing or stopping medication);
• Clinical symptoms or imaging findings worsen during tuberculosis treatment;
• Residing in or traveling to areas with a high prevalence of drug-resistant tuberculosis;
• Close contact with infectious drug-resistant tuberculosis patients.

DIAGNOSIS

How is tuberculosis diagnosed?

Chest X-ray or CT, sputum acid-fast bacilli smear, tuberculin skin test (PPD test), tuberculosis antibody test, interferon-gamma release assay (T-SPOT.TB), combined with clinical symptoms and signs.

What is the role of chest X-ray in tuberculosis diagnosis?

Chest X-rays are primarily used for screening and follow-up of pulmonary tuberculosis, aiming to determine whether the chest is normal or abnormal. They can detect early-stage TB with mild symptoms and monitor disease progression and treatment efficacy.

What is the role of chest CT in tuberculosis diagnosis?

Chest CT is more valuable than X-rays for detecting and differentiating tuberculosis from other lung diseases, especially for distinguishing TB from lung cancer. Its advantages in TB diagnosis include:

• Avoiding overlapping images, revealing areas obscured on X-rays;
• High resolution, displaying lesions at different stages of TB;
• Detecting early miliary tuberculosis, etc.

What tests are needed to confirm Mycobacterium tuberculosis in patients?

Tests include: smear microscopy, mycobacterial culture, species identification, and drug susceptibility testing.

• Smear microscopy: Commonly uses acid-fast staining in China—simple, fast, and low-cost. However, it has low detection rates, is operator-dependent, and cannot distinguish M. tuberculosis from non-tuberculous mycobacteria (except M. leprae).

• Mycobacterial culture: Methods like Löwenstein-Jensen culture, Bactec-TB960, and BacT/Alert 3D provide bases for species identification and drug testing. The first method takes 1–2 months (low sensitivity, inexpensive), while the latter two take ~15 days (high sensitivity, costly, limited to specialized hospitals).

• Species identification: Determines whether the bacteria are M. tuberculosis, M. bovis, or non-tuberculous mycobacteria.

• Drug susceptibility testing: Guides antibiotic selection to reduce drug resistance.

What is the significance of sputum TB testing?

Though positivity rates are low, it is highly informative for diagnosis. Sputum-positive patients are key TB transmitters, making testing vital for prevention.

How to collect qualified sputum samples for TB testing?

• Rinse mouth to remove food debris;
• Cough deeply to produce 3+ mL of mucus, purulent, or caseous sputum;
• Use nebulization for low-sputum patients;
• Use sterile containers and deliver promptly;
• Collect samples 48+ hours post-anti-TB medication.

What does the tuberculin skin test indicate in TB diagnosis?

A positive result only confirms prior TB exposure, not active disease. For unvaccinated children, it may warrant preventive therapy.

TREATMENT

Which department should I visit for tuberculosis?

If tuberculosis is suspected, you can go to the Infectious Diseases Department. After diagnosis, you may need to be referred to a specialized hospital with tuberculosis treatment qualifications.

What are the principles of oral medication for tuberculosis?

• Early treatment principle: Early treatment helps tuberculosis drugs penetrate the lesions, promotes tissue repair, and effectively kills tuberculosis bacteria. The earlier the treatment, the better the recovery of affected tissues.

• Combination therapy principle: Using multiple drugs together improves bactericidal efficacy and prevents drug resistance.

• Appropriate dosage principle: Too low a dose may lead to drug resistance, while too high a dose increases side effects. Dosage should be adjusted based on the patient's age, weight, and medication guidelines.

• Regular medication principle: Taking medication regularly maintains stable drug concentrations in the body for effective bactericidal action. Irregular use leads to fluctuating drug levels, which not only fails to kill bacteria but also increases resistance.

• Full-course treatment principle: Strict adherence to the prescribed treatment duration is necessary. Otherwise, treatment failure, recurrence, and drug resistance rates may increase.

• Immunotherapy principle: Immunotherapy enhances the body's specific immune protection and bactericidal capacity through immunomodulatory drugs, assisting anti-tuberculosis medications in killing tuberculosis bacteria.

What is the role of immunotherapy in tuberculosis?

Anti-tuberculosis drugs can kill rapidly multiplying tuberculosis bacteria but are less effective against slow-growing or intermittently active bacteria, drug-resistant strains, and dormant bacteria. These types of bacteria can only be eradicated with the help of immunotherapy, achieving complete cure.

What are the consequences of not undergoing strict standardized tuberculosis treatment?

In terms of cure rates, strict standardized treatment has a success rate of over 90%, whereas improper treatment only achieves a 45% success rate.

The risks include not only a lower cure rate but also higher recurrence rates and the development of drug-resistant tuberculosis. Subsequent treatments become far less effective, potentially leading to chronic, untreatable infectious cases.

What are the characteristics of the tuberculosis drug isoniazid?

Isoniazid is a first-line anti-tuberculosis drug effective against both intracellular and extracellular tuberculosis bacteria. It is low in toxicity, easily absorbed, and inexpensive. Combined with other anti-tuberculosis drugs, it delays resistance and has synergistic antibacterial effects.

Common side effects: Peripheral neuritis (seek medical attention if numbness in hands or feet occurs); liver damage; occasional cases of gynecomastia in males, and reduced white blood cell counts.

What are the characteristics of the tuberculosis drug rifampin?

Rifampin is a first-line anti-tuberculosis drug and a broad-spectrum antibiotic. Resistance develops quickly if used alone, so it is often combined with other drugs.

The most common side effects are liver damage and gastrointestinal reactions. Seek medical attention if appetite loss or jaundice occurs. Liver function should be monitored regularly during treatment.

Why is rifapentine increasingly used in tuberculosis treatment?

Rifapentine has 2–10 times the bactericidal activity of rifampin, remains in the body longer, and requires only one-third the dose. It has fewer and milder side effects than rifampin, making it suitable for hepatitis B carriers, patients with liver dysfunction, and the elderly. It is considered highly effective, long-lasting, low in toxicity, and cost-effective.

Can tuberculosis be cured?

Patients diagnosed with tuberculosis must follow the principles of "early, regular, full-course, appropriate, and combination" treatment under medical supervision. This approach can kill tuberculosis bacteria and heal lesions, allowing most patients to recover.

What are the criteria for tuberculosis cure?

A tuberculosis patient is considered clinically cured after completing the prescribed treatment course and testing negative for acid-fast bacilli in multiple sputum tests.

For general tuberculosis, a negative sputum test or no disease reactivation after 2 years confirms recovery. For cavitary tuberculosis, this period extends to 3 years.

When can tuberculosis patients stop medication?

Patients should only stop medication after completing the full prescribed course, except in cases of severe drug side effects.

When do tuberculosis patients require hospitalization?

After two weeks of regular treatment, over 90% of tuberculosis bacteria are eliminated, and sputum tests turn negative in over 90% of cases after two months, significantly reducing or eliminating infectivity. Thus, mild cases can be treated without hospitalization.

Only severe, complicated cases, those with serious complications, or requiring surgery need hospitalization.

Who should receive preventive tuberculosis treatment?

Not everyone infected with tuberculosis develops the disease, so preventive treatment is unnecessary for all. However, the following groups should consider it:

• Children exposed to sputum-positive tuberculosis patients, especially those with a tuberculin reaction >15 mm (or with blisters/papules);
• HIV/tuberculosis co-infected individuals and other high-risk groups (diabetes, pneumoconiosis, gastrectomy, long-term immunosuppressant use, untreated inactive lung tuberculosis, etc.).

Why do tuberculosis patients need regular liver and kidney function tests?

• The liver metabolizes drugs and toxins, and many anti-tuberculosis drugs (e.g., isoniazid, rifampin, pyrazinamide) are liver-processed, increasing the risk of drug-induced liver damage.
• The kidneys excrete many anti-tuberculosis drugs (e.g., pyrazinamide, amikacin, streptomycin), which may harm kidney function. Monthly liver and kidney function tests are necessary.

How should tuberculosis be treated during pregnancy?

Successful standard tuberculosis treatment is key to a healthy pregnancy.

First-line drugs (isoniazid, rifampin, pyrazinamide, ethambutol) are safe during pregnancy, except streptomycin, which is ototoxic to the fetus. Pregnant or breastfeeding women on isoniazid should take vitamin B6 supplements.

How should tuberculosis be treated during breastfeeding?

If tuberculosis is diagnosed postpartum, breastfeeding is not recommended. Mothers should complete the full tuberculosis treatment course.

• Breastfeeding increases nutritional demands, worsening the mother’s physical and mental burden and hindering recovery.
• Many drugs pass into breast milk, affecting infant development. Infectious mothers may also transmit tuberculosis through close contact.

How is drug-resistant tuberculosis treated?

First, Mycobacterium tuberculosis must be cultured to guide treatment, a process taking at least two weeks.

While awaiting results, empirical treatment may be initiated based on severity:

• For highly suspected or severe cases, add ≥2 other drugs (e.g., fluoroquinolones) to first-line therapy. Severe infections (e.g., TB meningitis/miliary TB) require ≥3 additional drugs.
• Mild cases can wait for culture results before adjusting treatment.

Treatment is adjusted based on culture results.

Can drug-resistant tuberculosis be treated surgically?

Yes.

Surgery (e.g., lobectomy, wedge resection, pneumonectomy) is an option for patients unresponsive to or intolerant of standard drugs, with resectable lung lesions and adequate lung function.

DIET & LIFESTYLE

Can tuberculosis patients breastfeed?

Breastfeeding is not recommended.

Reasons: It increases the mother's nutritional demands, worsens her mental and physical burden, affects rest, and is detrimental to tuberculosis treatment and recovery. Some anti-tuberculosis drugs are secreted in breast milk, which may affect infant development. If the mother has infectious pulmonary tuberculosis, the baby may also become infected.

Does smoking affect tuberculosis?

Smoking has a significant impact on tuberculosis:

• It may delay the detection and diagnosis of tuberculosis because smoking often causes coughing and phlegm, which can mask tuberculosis symptoms.
• It promotes the development of tuberculosis. Heavy smoking damages the respiratory mucosa and alveoli, weakens local immunity, and reduces resistance to tuberculosis bacteria. The risk of tuberculosis increases with smoking.
• Smoking affects the efficacy of drug treatment. Smokers often have complications like gastrointestinal ulcers, which worsen the side effects of tuberculosis drugs and make medication difficult.

Can tuberculosis patients drink alcohol?

Tuberculosis patients should avoid alcohol.

Alcohol is metabolized by the liver, as are many anti-tuberculosis drugs. Drinking increases liver burden, leading to liver damage and impaired drug metabolism, which may cause drug accumulation and toxicity. Mild cases may show elevated liver enzymes or bilirubin, while severe cases can lead to liver failure.

Additionally, alcohol dilates blood vessels, increasing the risk of hemoptysis in pulmonary tuberculosis.

Can tuberculosis patients get pregnant?

Women with active tuberculosis should avoid pregnancy. If already pregnant, consult an obstetrician.

Pregnancy lowers immunity, worsening tuberculosis. Anti-tuberculosis drugs significantly affect fetal development. Severe tuberculosis may cause fetal hypoxia, malnutrition, or stillbirth. The bacteria may also infect the fetus, causing congenital tuberculosis.

How can tuberculosis patients recuperate at home?

• Take medication regularly. If missed, take within 24 hours.
• Maintain a regular routine and engage in light activities without overexertion.
• Eat a balanced diet rich in calories, protein, and fats, with plenty of fresh fruits and vegetables.
• Avoid crowded living conditions; ideally, stay in a separate room to prevent transmission.
• Do not spit in public. Spit into a tissue and dispose of it properly.

What should tuberculosis patients pay attention to in their diet?

• No dietary restrictions. Eat nutritious foods like meat, fish, and vegetables, but avoid overly spicy or salty foods, which worsen coughing.
• Avoid alcohol, as it worsens liver damage from drugs and may cause hemoptysis.
• Quit smoking, as it reduces drug efficacy and promotes tuberculosis activity.

How should tuberculosis patients disinfect household items?

Tuberculosis bacteria are highly contagious. Patients should stay in a separate room and use dedicated items.

• Utensils: Boil for 5 minutes before washing.
• Toilet bowls or spittoons: Soak in 84 disinfectant or 0.1% peracetic acid for 1 hour before cleaning.
• Bedding or books: Sun-dry for at least 2 hours.
• Indoor spaces: Use UV light for 2 hours daily.
• Cover mouth and nose when coughing/sneezing. Do not spit randomly—use a covered container with disinfectant.

PREVENTION

How to Prevent Tuberculosis Infection in Children

• Timely detection and complete cure of family members with tuberculosis who test positive for tubercle bacilli in sputum. Minimize contact with children within the first 2 weeks of treatment initiation;

• For children already infected with tuberculosis bacteria but without active disease, especially those with a PPD test result >15 mm, preventive treatment can be administered;

• Newborn vaccination with BCG can enhance resistance to tuberculosis bacteria and reduce the occurrence of severe forms (e.g., miliary tuberculosis, tuberculous meningitis), though it cannot completely prevent tuberculosis;

• Maintaining regular routines, balanced diets, and appropriate outdoor activities also greatly helps strengthen immunity.