What is Drug-resistant Tuberculosis
(MDR-TB)?
Multi-drug-resistant tuberculosis (MDR-TB)
is a form of tuberculosis (TB) infection caused by bacteria that are resistant
to treatment with at least two of the most powerful first-line anti-TB
medications (drugs), isoniazid and rifampin. Some forms of TB are also
resistant to second-line medications, and are called extensively drug-resistant
TB (XDR-TB).
Tuberculosis (TB) is a disease caused by
bacteria that are spread from person to person through the air. TB usually
affects the lungs, but it can also affect other parts of the body, such as the
brain, the kidneys, or the spine. In most cases, TB is treatable and curable;
however, people with TB can die if they do not get proper treatment. Sometimes
drug-resistant TB occurs when bacteria become resistant to the drugs used to
treat TB. This means that the drug can no longer kill the TB bacteria.
Drug-resistant TB (DR TB) is spread the same
way that drug-susceptible TB is spread. TB is spread through the air from one
person to another. The TB bacteria are put into the air when a person with TB
disease of the lungs or throat coughs, sneezes, speaks, or sings. People nearby
may breathe in these bacteria and become infected.
What are the causes of Drug-resistant Tuberculosis (MDR-TB)?
Drug-resistant TB can occur when the drugs
used to treat TB are misused or mismanaged. Examples of misuse or mismanagement
include:
People do not complete a full course of TB
treatment
Health care providers prescribe the wrong
treatment (the wrong dose or length of time)
Drugs for proper treatment are not available
Drugs are of poor quality
Drug-resistant TB is more common in people
who:
Do not take their TB drugs regularly
Do not take all of their TB drugs
Develop TB disease again, after being
treated for TB disease in the past
Come from areas of the world where
drug-resistant TB is common
Have spent time with someone known to have
drug-resistant TB disease
What are the types of Drug-resistant TB?
There are two types of Drug-resistant TB.
Multidrug-Resistant TB (MDR TB)
Multidrug-resistant TB (MDR TB) is caused by
TB bacteria that is resistant to at least isoniazid and rifampin, the two most
potent TB drugs. These drugs are used to treat all persons with TB disease.
TB experts should be consulted in the
treatment of MDR TB.
Extensively Drug-resistant TB (XDR TB)
Extensively drug-resistant TB (XDR TB) is a
rare type of MDR TB that is resistant to isoniazid and rifampin, plus any
fluoroquinolone and at least one of three injectable second-line drugs (i.e.,
amikacin, kanamycin, or capreomycin).
Because XDR TB is resistant to the most
potent TB drugs, patients are left with treatment options that are much less
effective.
XDR TB is of special concern for people with
HIV infection or other conditions that can weaken the immune system. These
people are more likely to develop TB disease once they are infected, and also
have a higher risk of death once they develop TB.
How to prevent Drug-resistant TB (XDR
TB)?
The most important way to prevent the spread
of drug-resistant TB is to take all TB drugs exactly as prescribed by the
health care provider. No doses should be missed and treatment should not be
stopped early. People receiving treatment for TB disease should tell their
health care provider if they are having trouble taking the drugs.
Health care providers can help prevent
drug-resistant TB by quickly diagnosing cases, following recommended treatment
guidelines, monitoring patients’ response to treatment, and making sure therapy
is completed.
Another way to prevent getting
drug-resistant TB is to avoid exposure to known drug-resistant TB patients in
closed or crowded places such as hospitals, prisons, or homeless shelters.
People who work in hospitals or health-care settings where TB patients are
likely to be seen should consult infection control or occupational health
experts.
What is the treatment for Drug-resistant
TB?
Drug-resistant TB is caused by TB bacteria
that are resistant to at least one first-line anti-TB drug. Multidrug-resistant
TB (MDR TB) is resistant to more than one anti-TB drug and at least isoniazid
(INH) and rifampin (RIF).
Extensively drug-resistant TB (XDR TB) is a
rare type of MDR TB that is resistant to isoniazid and rifampin, plus any
fluoroquinolone and at least one of three injectable second-line drugs (i.e.,
amikacin, kanamycin, or capreomycin).
Treating and curing drug-resistant TB is
complicated. Inappropriate management can have life-threatening results.
Drug-resistant TB should be managed by or in close consultation with an expert
in the disease.
Usually, multidrug-resistant tuberculosis
can be cured with long treatments of second-line drugs, but these are more
expensive than first-line drugs and have more adverse effects.
The majority of patients suffering from
multi-drug-resistant tuberculosis do not receive treatment, as they are found
in underdeveloped countries or in poverty. Denial of treatment remains a
difficult human rights issue, as the high cost of second-line medications often
precludes those who cannot afford therapy.
