Chapter 216 Tuberculosis

Question 1

What is the cause of tuberculosis (TB)?

Answer 1

Mycobacterium tuberculosis

TB is an airborne infectious disease caused by this acid-fast aerobic bacterium.

Question 2

What are some other Mycobacterium species that can cause disease in humans?

Answer 2

• Mycobacterium bovis
• Mycobacterium avium
• Mycobacterium africanum

These species can cause TB in specific populations, such as cattle and birds.

Question 3

What is the 13th leading cause of death worldwide?

Answer 3

Tuberculosis (TB)

It is the second leading cause of death from an infectious agent after COVID-19.

Question 4

What percentage of the world’s population has latent mycobacterium tuberculosis infection?

Answer 4

25%

There is a 5% to 10% lifetime progression to active TB disease.

Question 5

Which countries accounted for 86% of new TB cases in 2020?

Answer 5

• India
• China
• Indonesia
• Philippines
• Pakistan
• Nigeria
• Bangladesh
• South Africa

These are the countries with the highest percentage of TB cases.

Question 6

What is the risk of progression to active TB disease for infants younger than 1 year?

Answer 6

43%

This is the highest risk compared to other age groups.

Question 7

True or false: The COVID-19 pandemic has led to an increase in TB deaths worldwide.

Answer 7

TRUE

The pandemic reversed years of progress in TB management.

Question 8

What was the reported number of TB cases in the United States from 1953 to 1985?

Answer 8

Dropped from 84,000 to 22,000

This period marked relatively successful control of TB.

Question 9

What is the current trend of TB incidence in the United States since 2010?

Answer 9

Decreased by an average of 2% to 3% annually

This contrasts with global trends where TB cases have increased.

Question 10

What is MDR-TB?

Answer 10

Multidrug-resistant tuberculosis

It refers to TB that is resistant to at least INH and rifampin.

Question 11

What does RR-TB stand for?

Answer 11

Rifampicin-resistant tuberculosis

It is a form of TB that is resistant to rifampicin.

Question 12

What is the emergence rate of MDR-TB globally?

Answer 12

Increased by an annual rate of more than 20%

This poses a significant threat to TB control.

Question 13

What are the core TB drugs that XDR-TB is resistant to?

Answer 13

• INH
• Rifampin
• Fluoroquinolones
• Injectable second-line drugs (amikacin, capreomycin, kanamycin)

XDR-TB is a severe form of drug resistance in TB.

Question 14

What is the impact of substance use on TB transmission?

Answer 14

Increases risk of TB transmission

Substance use decreases likelihood of seeking medical care and adherence to therapy.

Question 15

What is the recommended screening for health care personnel regarding TB?

Answer 15

Screened for TB upon hire

Local health departments should be notified if TB disease is suspected.

Question 16

What is the public health responsibility in treating TB?

Answer 16

Ensuring adherence to the treatment regimen

Treatment benefits both the individual and the community.

Question 17

What is the ethical perspective on the global TB epidemic?

Answer 17

Affects predominantly the most vulnerable populations

Continued support for TB control programs is essential.

Question 18

What are the three factors that influence TB transmission?

Answer 18

• Infectiousness of the person with TB
• Environment of exposure
• Duration of exposure

These factors determine the likelihood of transmission.

Question 19

What is the most common clinical form of TB disease?

Answer 19

Reactivation or postprimary disease

This form is prevalent in individuals with prior latent TB infection.

Question 20

What percentage of all TB cases involve the lungs?

Answer 20

85%

Other common sites include the pleura, CNS, lymphatic system, genitourinary system, and bones and joints.

Question 21

What are the two distinct epidemiologic patterns of TB disease?

Answer 21

• Reactivation (postprimary disease)
• Primary infection

Reactivation is the most common clinical form, while primary infection is usually asymptomatic except in HIV-infected individuals.

Question 22

True or false: Most persons with primary infection of TB are symptomatic.

Answer 22

FALSE

More than 90% of persons with primary infection are asymptomatic.

Question 23

List some medical conditions that increase the risk of progression from LTBI to active TB disease.

Answer 23

• HIV infection
• Diabetes mellitus
• Silicosis
• Substance use
• Prolonged corticosteroid therapy
• Cancer of the head and neck
• End-stage renal disease
• Low body weight

These conditions can significantly increase the risk of developing active TB.

Question 24

What does LTBI stand for?

Answer 24

Latent Tuberculosis Infection

Individuals with LTBI are asymptomatic and do not have active TB disease.

Question 25

What are common **symptoms** of pulmonary TB?

Answer 25

* Fatigue * Anorexia * Weight loss * Night sweats * Cough * Chest pain * Hemoptysis * Low-grade fever ## Footnote Symptoms may be subtle and can mimic other illnesses.

Question 26

What is the **standard method** of screening for TB infection?

Answer 26

Mantoux test ## Footnote This test involves injecting purified protein derivative (PPD) intradermally.

Question 27

What is the **criteria for a positive TST reaction** for persons with HIV infection?

Answer 27

Induration ≥ 5 mm ## Footnote This indicates a significant reaction to the tuberculin skin test.

Question 28

What is the **role of IGRAs** in TB diagnostics?

Answer 28

Measure immune reactivity to specific mycobacterial antigens ## Footnote IGRAs do not require a second test for boosting.

Question 29

What is the **BCG vaccine** used for?

Answer 29

Prevent TB ## Footnote It was first introduced in 1921 and is the most widely used vaccine worldwide.

Question 30

What is the **Mantoux test** administered with?

Answer 30

5 tuberculin units (0.1 mL) of PPD solution ## Footnote The injection should produce a wheal of 6 to 10 mm in diameter.

Question 31

What is the **time frame** for reading the results of a TST?

Answer 31

48 to 72 hours ## Footnote If the patient does not return within this time, a positive reaction may still be measurable up to 1 week later.

Question 32

What are some **potential causes** of false-negative TST reactions?

Answer 32

* Age * Immunosuppression * Live virus vaccinations * Malnutrition * Chronic renal failure * Stress ## Footnote These factors can affect the accuracy of the TST results.

Question 33

What is the **two-step TST** method used for?

Answer 33

To identify previously infected individuals ## Footnote If the first test is negative, a second test is given 1-3 weeks later.

Question 34

What does **BCG** stand for in the context of tuberculosis vaccination?

Answer 34

Bacillus Calmette-Guérin ## Footnote BCG is the only vaccine used to prevent TB and has nonspecific immunologic effects.

Question 35

What are the benefits of **BCG** vaccination?

Answer 35

* Prevents miliary TB * Prevents TB meningitis in children * Helpful in treating bladder cancer * Effective against common and genital warts ## Footnote BCG has shown efficacy in preventing certain forms of TB but is not as effective in preventing pulmonary TB in adults.

Question 36

True or false: **BCG** is recommended for use in the United States due to high risk of infection with M. tuberculosis.

Answer 36

FALSE ## Footnote BCG is not generally recommended in the U.S. because of the low risk of infection and variable effectiveness against adult pulmonary TB.

Question 37

What factors affect **tuberculin sensitivity** in individuals who have received the BCG vaccination?

Answer 37

* Strain of BCG used * Individual vaccinated ## Footnote Sensitivity to tuberculin varies significantly among persons vaccinated with BCG.

Question 38

What is the role of **IGRAs** in tuberculosis testing?

Answer 38

* Used in all situations where TST is used * Results available 24 hours after blood collection * No need for two-step testing ## Footnote IGRAs are cost-effective and reduce false-positive results in populations with many BCG-vaccinated individuals.

Question 39

What are the **limitations of IGRAs**?

Answer 39

* Blood samples must be processed within 8 to 16 hours * Limited data on use in young children and immunocompromised persons * Cost burden on microbiology staff ## Footnote IGRAs may not be suitable for all settings due to processing difficulties.

Question 40

What is the **preferred method of testing** for children younger than 5 years for TB?

Answer 40

TST ## Footnote IGRAs are preferred for groups with poor rates of returning for TST results.

Question 41

What should be done for persons with a positive TST or IGRA reaction?

Answer 41

* Anteroposterior chest radiograph to exclude active pulmonary TB * Evaluate for fibrotic lesions ## Footnote Chest radiographs help to rule out active TB and are not diagnostic by themselves.

Question 42

What is the **clinical classification system** for tuberculosis?

Answer 42

* Class 0: No TB exposure * Class 1: TB exposure, no evidence of infection * Class 2: TB infection, no disease * Class 3: TB, clinically active * Class 4: TB, not clinically active * Class 5: TB suspected ## Footnote This classification helps guide treatment and management of TB.

Question 43

What are the **high-priority candidates** for tuberculosis preventive therapy?

Answer 43

* Persons with known or suspected HIV infection * Close contacts of infectious TB * Persons with suggestive chest X-ray findings * Persons who inject drugs * Recent TST converters * Persons with medical conditions increasing TB risk ## Footnote Preventive therapy is recommended regardless of age for these individuals.

Question 44

What are the recommended **treatment regimens** for latent TB infection in the U.S.?

Answer 44

* 3 months of once-weekly INH plus rifapentine (3HP) * 4 months of daily rifampin (4R) * 3 months of daily INH plus rifampin (3HR) ## Footnote Short-course regimens are preferred due to higher completion rates and lower risk of hepatotoxicity.

Question 45

What are the **effective and safe treatment regimens** for latent tuberculosis infection?

Answer 45

* 3HP * 4R * 6H * 9H ## Footnote 3HP and 4R have higher completion rates than longer regimens of INH monotherapy (6H/9H).

Question 46

The **3HP regimen** consists of how many doses and what is the frequency?

Answer 46

12 once-a-week doses ## Footnote The 3HP regimen can be given under directly observed therapy (DOT) or self-administered therapy (SAT).

Question 47

Who is the **3HP regimen** recommended for?

Answer 47

* People older than 2 years * People with HIV/AIDS on compatible antiretroviral medications ## Footnote It is not recommended for children younger than 2 years or those with certain drug interactions.

Question 48

What is the **4R regimen** recommended for?

Answer 48

* HIV-negative adults * Children of all ages * Those who cannot tolerate INH ## Footnote The 4R regimen is a 4-month regimen of RIF.

Question 49

What are the **alternative treatment regimens** if short-course treatment is not an option?

Answer 49

* 6 months of daily INH (6H) * 9 months of daily INH (9H) ## Footnote These regimens have higher liver toxicity risk and lower completion rates than shorter rifamycin-based regimens.

Question 50

What are the **common negative side effects** of medications used to treat latent TB infection?

Answer 50

* Nausea * Vomiting * Abdominal pain * Blurred vision * Loss of appetite * Jaundice * Fever * Rash or itching * Tingling or burning in hands or feet * Fatigue * Photosensitivity ## Footnote Patients taking RIF or RPT may notice orange discoloration of urine and other body fluids.

Question 51

True or false: **RIF and RPT** are contraindicated in individuals with HIV infection who are treated with protease inhibitors.

Answer 51

TRUE ## Footnote RIF and RPT can decrease blood levels of many drugs.

Question 52

What should be monitored for patients treated with the **3HP regimen**?

Answer 52

* Monthly evaluations for adverse events * Baseline liver enzymes ## Footnote Discontinue treatment if ALT/AST concentrations are significantly elevated.

Question 53

What is the purpose of therapy for **active TB**?

Answer 53

To prevent the development of MDR-TB ## Footnote The medication regimen is based on drug susceptibilities.

Question 54

What is the definition of **class 4 TB**?

Answer 54

History of previous TB episodes or stable radiographic findings with negative sputum cultures ## Footnote Current clinically active TB must be excluded before assigning to class 4.

Question 55

What is the **DOTS program** introduced by WHO?

Answer 55

* Case detection by sputum-smear microscopy * Government commitment to TB control * Regular supply of TB drugs * Supervised treatment * Reports on health system progress ## Footnote DOTS has been implemented in over 180 countries.

Question 56

What are the **treatment regimens** for latent tuberculosis infection?

Answer 56

* 3 months of INH and RPT * 4 months of RIF * 3 months of INH and RIF * 6 months of INH * 9 months of INH ## Footnote Each regimen has specific dosing and frequency requirements.

Question 57

What is the **maximum dose** for adults taking RIF in the 4-month regimen?

Answer 57

600 mg ## Footnote The regimen is daily for 4 months.

Question 58

What is a significant problem associated with **TB control**?

Answer 58

Adherence to antitubercular regimens ## Footnote Many variables affect a person’s adherence, including misinformation and access to healthcare.

Question 59

What does **DOT** stand for in the context of TB medication?

Answer 59

Directly Observed Therapy ## Footnote DOT involves trained personnel observing the patient taking each dose of TB medication.

Question 60

True or false: **DOT** is only implemented in hospital settings.

Answer 60

FALSE ## Footnote DOT is routinely implemented in various areas, including homeless shelters and patients' homes.

Question 61

What are the benefits of using **intermittent regimens** in DOT?

Answer 61

* Less burdensome for patients * Cost-effective * Decrease in acquisition and transmission of TB ## Footnote Intermittent regimens can be prescribed to be taken two or three times weekly.

Question 62

What is required by law in every state regarding a diagnosis of **TB**?

Answer 62

* Report to the local health department * Forward drug susceptibility test results ## Footnote Reporting is important for source identification, epidemiologic surveillance, and resource provision.

Question 63

Who should be consulted for the management of patients requiring **multidrug therapy** for TB?

Answer 63

A specialist ## Footnote This includes patients with active clinical disease and those with coexistent medical conditions affecting immune responsiveness.

Question 64

Most patients with clinically active **pulmonary TB** should be considered for _______ during the first couple of weeks of therapy.

Answer 64

hospitalization ## Footnote After 2 weeks of therapy, patients are significantly less infectious.

Question 65

What type of patients should be referred to an **infectious disease specialist**?

Answer 65

* Persons with MDR/RR-TB * Immunocompromised patients with active TB * Patients with disseminated disease ## Footnote These patients require specialized management.

Question 66

What is the standard regimen for treating **LTBI** in pregnant women?

Answer 66

* INH administered daily or twice weekly for 9 months * Supplementation with 50 to 100 mg of pyridoxine daily ## Footnote Treatment should be deferred unless specific risk factors are present.

Question 67

What should be monitored closely in pregnant women receiving **INH**?

Answer 67

Hepatotoxicity ## Footnote There is an increased risk during pregnancy and for 2 to 3 months postpartum.

Question 68

What is the preferred initial drug regimen for pregnant women with **clinically active TB**?

Answer 68

* INH * Rifampin * Ethambutol ## Footnote These drugs cross the placenta but have no demonstrated teratogenic side effects.

Question 69

What is the death rate of untreated **pulmonary TB**?

Answer 69

Approximately 60% ## Footnote The median time until death is 2½ years.

Question 70

What is the relationship between **TB** and **HIV/AIDS**?

Answer 70

* TB is the leading cause of death among HIV positive individuals * Each disease accelerates the progression of the other ## Footnote TB accounts for approximately 30% of AIDS-related deaths worldwide.

Question 71

What is a significant risk factor for acquiring **TB infection**?

Answer 71

Smoking ## Footnote Smoking increases the risk of developing active TB and having a more severe form of the disease.

Question 72

What is critical for controlling the resurgence of **TB**?

Answer 72

Patient education ## Footnote Education about TB screening and the importance of identifying infected individuals is essential.

Question 73

What must be explained to patients regarding **medication adherence**?

Answer 73

* Untreated TB can lead to reactivation * Progression of the disease * Continued spread of the disease * Development of drug resistance ## Footnote These factors highlight the importance of adhering to treatment.

Question 74

What should patients be instructed to do if they experience signs of **drug toxicity**?

Answer 74

Contact their health care provider ## Footnote Potential drug side effects must be carefully discussed with patients.