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Extensively Drug-Resistant
Tuberculosis - XDR TB
CDC Factsheet
What is XDR
TB?
Extensively drug-resistant
tuberculosis (XDR TB) is a relatively rare type of multidrug-resistant
tuberculosis (MDR TB). It is resistant to almost all drugs used
to treat TB, including the two best first-line drugs: isoniazid
and rifampin. XDR TB is also resistant to the best second-line
medications: fluoroquinolones and at least one of three injectable
drugs (i.e., amikacin, kanamycin, or capreomycin).
How is XDR
TB spread?
Drug-susceptible (regular)
TB and XDR TB are spread the same way. TB germs are put into
the air when a person with TB disease of the lungs or throat
coughs, sneezes, speaks, or sings. These germs can float in the
air for several hours, depending on the environment. Persons
who breathe in the air containing these TB germs can become infected.
TB is not spread by
* shaking someone’s
hand
* sharing food or drink
* touching bed linens or toilet seats
* sharing toothbrushes
* kissing
* smoking or sharing cigarettes
Why is XDR
TB so serious?
Because XDR TB is resistant
to the most powerful first-line and second-line drugs, patients
are left with treatment options that are much less effective
and often have worse treatment outcomes. XDR TB is of special
concern for persons with HIV infection or other conditions that
can weaken the immune system. These persons are more likely to
develop TB disease once they are infected, and also have a higher
risk of death once they develop TB disease.
Who is at
risk for getting XDR TB?
Drug-resistant TB (MDR or
XDR) is more common in people who:
* Do not take their TB medicine
regularly
* Do not take all of their TB medicines as told by their doctor
or nurse
* Develop active TB disease again, after having taken TB medicine
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
How can I
prevent myself from getting TB?
Avoid close contact or prolonged
time with known TB patients in crowded, enclosed environments
like clinics, hospitals, prisons, or homeless shelters.
Can the TB vaccine (BCG) help prevent XDR TB?
There is a vaccine for TB
disease called Bacille Calmette-Guérin (BCG). It is used
in some countries to prevent severe forms of TB in children.
However, BCG is not generally recommended in the United States
because it has limited effectiveness for preventing TB in adults.
The effect of BCG against XDR TB would likely be similar to the
effect on drug-susceptible TB.
If I have
regular (drug-susceptible) TB, how can I prevent getting drug-resistant
TB?
The most important thing
is for you to continue taking all your TB medicines exactly as
prescribed. No doses should be missed and treatment should not
be stopped early. You should tell your health care provider if
you are having trouble taking the medications. If you plan to
travel, make sure you have enough medicine to last while away.
Can XDR TB
be treated and cured?
Yes, in some cases. Some
TB control programs have shown that cure is possible for an estimated
30% of affected people. Successful outcomes depend greatly on
the extent of the drug resistance, the severity of the disease,
and whether the patient’s immune system is weakened.
What are
the symptoms of XDR TB?
The general symptoms of TB
disease include feelings of sickness or weakness, weight loss,
fever, and night sweats. The symptoms of TB disease of the lungs
may also include coughing, chest pain, and coughing up blood.
Symptoms of TB disease in other parts of the body depend on the
area affected. If you have these symptoms, you should contact
your doctor or local health department.
What should
I do if I have been around someone who has XDR TB?
If you think you have been
exposed to someone with TB disease, you should contact your doctor
or local health department about getting a TB skin test or the
QuantiFERON®-TB Gold test (QFT-G), a blood test. And tell
the doctor or nurse when you spent time with this person.
How long
does it take to find out if you have XDR TB?
If TB bacteria are found
in the sputum (phlegm), the diagnosis of TB can be made in a
day or two, but this finding will not be able to distinguish
between drug-susceptible (regular) TB and drug-resistant TB.
To determine drug susceptibility, the bacteria need to be grown
and tested in a laboratory. Final diagnosis for TB, and especially
for XDR TB, may take from 6 to 16 weeks.
Is XDR TB
a problem in the United States?
The risk of acquiring XDR
TB in the United States appears to be relatively low. However,
it is important to acknowledge the ease at which TB can spread.
As long as XDR TB exists, the United States is at risk and must
address the threat.
How many
cases of XDR TB have been reported in the United States?
In the United States, 49
cases of XDR TB have been reported between 1993 and 2006.
Is it safe
to travel where cases of XDR TB have been reported?
Although MDR and XDR TB are
occurring globally, they are still rare. HIV-infected travelers
are at greatest risk if they come in contact with a person with
MDR or XDR TB.
All travelers should avoid
high risk settings where there are no infection control measures
in place. Documented places where transmission has occurred include
crowded hospitals, prisons, homeless shelters, and other settings
where susceptible persons come in contact with persons with TB
disease.
Air travel itself carries
a relatively low risk of infection with TB of any kind.
What can
health care providers do to prevent XDR TB?
Health care providers can
help prevent MDR and XDR TB by quickly diagnosing cases, following
recommended treatment guidelines, monitoring patients’ response
to treatment, and making sure therapy is completed.
Providers should also ensure
proper implementation of infection control procedures to prevent
exposure to TB in hospitals or health-care settings where TB
patients are likely to be seen.
Are immigrants
putting the U.S. at increased risk for TB?
Persons applying to enter
the U.S. with immigrant or refugee visas must complete a questionnaire
about any symptoms of TB they may have and obtain a chest radiograph.
If positive, the person submits sputum specimens for examination
for TB bacteria. Persons identified as having infectious TB are
not granted entry to the United States, until they have been
treated.
Why haven’t
we heard about XDR TB before now?
For some years we have seen
isolated cases of very highly resistant TB around the world that
we would today call XDR TB. The drugs used to treat TB have been
around a long time and drug resistance has taken many years to
develop. Over time, countries have improved their laboratory
capacity to test for drug resistance and their ability to track
the number of cases. All of these factors have contributed to
an increase in reporting of cases of drug-resistant TB. With
more cases being identified, the problem was more closely examined,
defined, and given a name.
What is CDC doing to
prevent XDR TB from becoming a bigger problem?
CDC is collaborating with
other federal agencies and international partners to raise awareness
and enhance strategies for TB prevention worldwide by
* Strengthening TB services
for people living with HIV/AIDS
* Assembling outbreak response teams
* Improving access to TB drugs
* Developing international TB testing standards
* Building capacity of health care providers to diagnose and
treat TB
* Reconvening the Federal TB Task Force
* Providing technical assistance to expand TB program capacity
* Supporting TB communication and education efforts
Source: CDC Factsheet 4/18/07
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