Self-Study Modules on Tuberculosis
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4: Treatment of Tuberculosis Infection and Disease
Answers To Study Questions
4.1. What is the purpose of preventive therapy?
The purpose of preventive therapy is to prevent people
with TB infection from developing TB disease.
4.2. Which groups of people should receive high priority
for preventive therapy if they have a positive skin test reaction,
regardless of their age? Name six.
- People with HIV infection
- Close contacts of people with infectious TB disease
- People whose skin test reaction converted from negative to positive
within the past 2 years
- People with chest x-ray findings suggestive of previous TB disease
- People who inject illicit drugs
- People with medical conditions that appear to increase the risk
for TB disease
4.3. Which groups of people should receive high priority
for preventive therapy if they have a positive skin test reaction
and are younger than 35? Name five.
- People born in areas of the world where TB is common (for example,
Asia, Africa, or Latin America)
- Low-income groups with poor access to health care
- People who live in residential facilities (for example, nursing
homes or correctional facilities)
- Children younger than 4 years old
- People in other groups as identified by local public health
4.4. In what circumstances may preventive therapy be given
to people who have a negative tuberculin skin test reaction?
Some close contacts may start taking preventive therapy
if they have a negative skin test reaction but less than 10 weeks
have passed since they were last exposed to TB. These contacts include
These contacts should be retested 10 weeks after they were last
exposed to TB. If they have a negative skin test reaction, they
can stop taking preventive therapy. (HIV-infected contacts may be
given a full course of preventive therapy, regardless of their skin
test results.) If they have a positive skin test reaction, they
should continue to take preventive therapy.
- High-risk contacts who have a negative skin test reaction
(including contacts who are anergic). High-risk contacts are
young children, adolescents, HIV-infected people, and others
who may develop TB very quickly after infection.
- Close contacts who have a negative skin test reaction, if
many other close contacts have a positive skin test reaction
Also, children younger than 6 months old who have been exposed
to TB should start taking preventive therapy, even if they have
a negative skin test reaction. The children should be retested
when they are 6 months old. If they have a negative skin test
reaction and 10 weeks have passed since they were last exposed
to TB, the preventive therapy may be stopped.
4.5. Name three reasons why patients should receive a medical
evaluation before starting preventive therapy.
All patients being considered for preventive therapy
should receive a medical evaluation to
- Exclude the possibility of TB disease
- Determine whether they have ever been treated for TB infection
- Identify any medical problems that may complicate therapy
or require more careful monitoring
4.6. Why is it important to exclude the possibility of
TB disease before giving a patient preventive therapy?
It is important to exclude the possibility of TB disease
because treating TB disease with a preventive therapy regimen (usually
a single drug) can lead to drug resistance.
4.7. What is the usual preventive therapy regimen? How
is it different for children and HIV-infected people?
The usual regimen for preventive therapy is isoniazid
given daily for 6 months. Children should receive at least 9 months
of preventive therapy; HIV-infected persons should receive 12 months
of preventive therapy.
4.8. What preventive therapy regimen is recommended for
people with a positive skin test reaction who have been exposed
to isoniazid-resistant TB?
Preventive therapy with rifampin is recommended in this
4.9. What adverse reactions may be caused by isoniazid?
Name two, and define each.
Isoniazid may cause hepatitis or peripheral neuropathy.
Hepatitis is damage to the liver. Peripheral neuropathy is damage
to the sensory nerves of the hands and feet.
4.10. What are the symptoms of hepatitis?
The common symptoms of hepatitis are nausea, vomiting,
abdominal pain, fatigue, and dark urine.
4.11. How often should patients be evaluated for signs
and symptoms of adverse reactions during preventive therapy?
All persons receiving preventive therapy should be evaluated
at least monthly during therapy for signs and symptoms of adverse
reactions. During each monthly evaluation, clinicians should ask
patients whether they have nausea, abdominal pain, or any of the
other symptoms that may be caused by adverse reactions. In addition,
they should examine patients for signs of these adverse reactions.
4.12. Who is at greatest risk for hepatitis? What special
precautions should be taken for these patients?
The people at greatest risk for hepatitis are
- People 35 years of age and older
- People with a history of liver disease
- People who abuse alcohol
- People who inject illicit drugs
- People who are taking other medications that may increase
the risk of hepatitis
These patients should have liver function tests before starting
isoniazid preventive therapy and every month during therapy. In
addition, more careful monitoring -- and possibly more liver function
tests -- should be considered for black and Hispanic women because
they may be at increased risk for isoniazid-associated hepatitis.
4.13. Why must TB disease be treated for at least 6 months?
TB disease must be treated for at least 6 months in order
to kill all of the tubercle bacilli. Most of the bacilli are killed
during the first 8 weeks of treatment (initial phase). However,
a few bacilli become dormant (inactive), and they can remain dormant
for a long time. The drugs used to treat TB do not work as well
against dormant bacilli as they do against bacilli that are growing
(active). Therefore, treatment must be continued for several more
months to kill these few remaining bacilli (continuation phase).
If treatment is not continued for a long enough time, some bacilli
may survive and cause TB disease at a later time (relapse).
4.14. Which four drugs are recommended for the initial
treatment of TB disease?
In most areas of the country, the initial regimen for
treating TB disease should include isoniazid (INH), rifampin (RIF),
pyrazinamide (PZA), and either ethambutol (EMB) or streptomycin
(SM). When the drug susceptibility results are available, clinicians
may change the regimen accordingly. In areas where less than 4%
of cases are resistant to INH (first drug susceptibility test only),
three drugs (INH, RIF, and PZA) may be adequate for the initial
4.15. Why should at least two drugs be used to treat TB
Using only one drug to treat TB disease can create a
population of tubercle bacilli that is resistant to that drug. When
two or more drugs are used together, each drug helps prevent the
emergence of bacilli that are resistant to the other drugs.
4.16. Name two factors that can lead to drug resistance.
Drug resistance can develop when patients are prescribed
an inappropriate regimen for treatment or when patients do not follow
treatment regimens as prescribed.
4.17. What is directly observed therapy? Why should it
be considered for all patients?
Directly observed therapy means that a health care worker
or another designated person watches the patient swallow each dose
of the prescribed drugs. This method of treatment should be considered
for all patients because there is no way to predict reliably which
patients will adhere to treatment.
4.18. In what special situations should treatment for TB
disease last longer than the usual course of treatment?
Infants and children with miliary TB, bone and joint
TB, or TB meningitis should receive at least 12 months of treatment.
Pregnant women with TB should receive at least 9 months of treatment.
Treatment for isoniazid-resistant TB can last 12 months when
a regimen of rifampin and ethambutol is used, and treatment for
multidrug-resistant TB can last 2 years or longer.
4.19. Name the drug or drugs that may cause each of the
following symptoms or adverse reactions.
Ear damage: streptomycin
Hepatitis: isoniazid, pyrazinamide, rifampin
Eye damage: ethambutol
Orange discoloration of the urine: rifampin
4.20. How often should patients be monitored for adverse
reactions to TB drugs?
All patients should be seen by a clinician at least monthly
during treatment and evaluated for possible adverse reactions. During
this evaluation, clinicians should ask patients whether they have
any of the symptoms that may be due to adverse reactions and examine
patients for signs of possible adverse reactions. Also, public health
workers who have regular contact with patients should ask patients
about adverse reactions at every visit.
4.21. Name four ways that clinicians can assess whether
a patient is adhering to treatment.
Check to see whether the patient is reporting to the clinic
Ask the patient to bring the prescribed medications to each
clinic visit and count the number of pills to determine how many
have been taken
Use special urine tests to detect the presence of the prescribed
medication in the urine
Assess the patient's clinical response to therapy
4.22. What is the best way to ensure that a patient adheres
The best way to ensure adherence to therapy is to use
directly observed therapy.
4.23. How can clinicians determine whether a patient is
responding to treatment?
To determine whether a patient is responding to therapy,
clinicians should do clinical evaluations and bacteriologic evaluations
during therapy. Clinicians may also use x-rays to monitor a patient's
response to treatment, especially in patients who have negative
culture results before treatment or who have certain types of extrapulmonary
4.24. Under what circumstances should patients be reevaluated?
Patients should be reevaluated promptly if their
- Symptoms do not improve during the first 2 months of therapy
- Symptoms worsen after improving initially
- Culture results have not become negative after 2 months of
- Culture results become positive after being negative
4.25. What does reevaluating the patient mean?
Reevaluating the patient means checking for drug resistance
by repeating the drug susceptibility tests and assessing whether
the patient has been taking medication as prescribed.
4.26. What should a public health worker do if he or she
notices that a patient has symptoms of an adverse reaction?
The public health worker should
- Instruct the patient to stop the medication if the symptoms
are serious (before working with TB patients, public health
workers should be educated about which symptoms are serious)
- Report the situation to a clinician and arrange for a medical
evaluation right away
- Note the symptoms on the patient's form