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
- sharing toothbrushes
- kissing smoking or sharing cigarettes
Why is XDR TB
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.
CDC Issues Isolation Order for Man with TB
Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR
In May 2007, the U.S. Centers for Disease Control and Prevention(CDC)
issued an order to quarantine a man who flew on two transatlantic flights with a rare, dangerous form of tuberculosisand potentially exposed passengers and
crew to the infection.
The Atlanta man was believed to be infected with the form of the tuberculosis bacteria known
as “extensively drug-resistant” TB, abbreviated XDR TB. Tuberculosis is a
bacterial infection that primarily affects the lungs, and the infection is
spread via air droplets released during coughing, spitting, sneezing, or
talking. XDR TB causes the same symptoms that a person would develop with TB. If TB disease is present, cough and feverwould be the predominant symptoms. XDR TB is a rare form of the disease that is resistant to the drugs
routinely used to treat tuberculosis infections and is extremely difficult to
treat. The few treatment options available for XDR TB are less effective and
associated with worse outcomes than traditional antibiotic therapies for TB. In
2006, there were two documented cases of XDR TB in the U.S.
Health authorities were aware of the man’s condition and had warned the man
against traveling, but he stated that compelling personal reasons led him to fly
from Atlanta to Paris on May 13. On May 24, he returned to North America on a
flight from Prague to Montreal and entered the U.S. by car. While it is not
certain that passengers and crew on board the flights were infected, the CDC
recommended that passengers and crew on those flights be tested for TB
infection. Particularly those seated within two rows of the infected man are at
greatest risk for infection.
After his return to the U.S., the man cooperated with authorities and
voluntarily entered a hospital in Atlanta and was placed in respiratory
isolation to prevent spread of the infection. This event marked the first time
since 1963, when a patient with smallpox was quarantined, that the CDC
issued this type of isolation order.
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
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-Guerin (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
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.
Extensively Drug-Resistant Tuberculosis (XDR TB)
See pictures of Bacterial Skin Conditions
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.
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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?
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?
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
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?
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
- 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