Extensively Drug-Resistant Tuberculosis (XDR TB) Fact Sheet

March 2013

Extensively drug-resistant tuberculosis (XDR TB) is a strain of TB resistant to at least isoniazied and rifampin among the first-line anti-TB drugs and to any fluoroquinolone and at least one of the three second-line injectable drugs: capreomycin, kanamycin, or amikan.1 XDR TB has emerged worldwide as a threat to public health and TB control, raising concerns of a future epidemic of virtually untreatable TB.2

It is speculated that XDR TB emerged from multidrug-resistant tuberculosis (MDR TB) as that strain is also resistant to the primary drugs isoniazid and rifampin. Resistance to one or several forms of treatment occurs when the bacteria develops the ability to withstand antibiotic attack and relays that ability to its offspring. Since that entire strain of bacteria inherits the capacity to resist the effects of the various treatments, resistance can spread from one person to another. On an individual basis, however, inadequate treatment or improper use of the anti-tuberculosis medications remains an important cause of drug-resistant tuberculosis. Drug-resistant TB is difficult and costly to treat and can be fatal.3

  • In 2009, 529 people died of tuberculosis, a slight decrease from the 590 deaths in 2008.4
  • In 2011, 6 cases of XDR TB were reported. Since the peak of 10 cases in 1993, between zero and 6 cases have been reported every year in the U.S.5

Number of XDR Cases by Year

  • The number of XDR TB cases among foreign-born persons was almost the same during 1993-1999 and 2000-2006 (12 and 13, respectively), but the percentage among this group increased from 39 percent to 76 percent as the number of XDR TB cases among U.S.-born persons declined.6 At least 4 of the 6 (67%) cases in 2011 were among foreign-born persons.7
  • Among non-Hispanic blacks, both the number and percent of total cases of XDR TB decreased from 1993-1999 to 2000-2006, from 9 (32%) to 2 (12%). However, this trend was reversed among Asians as the number and percent of cases increased from 3 (9%) to 7 (41%) over these two time periods.8
  • In 2011, a total of 98 cases of MDR TB were reported, which was an increase from the 89 cases reported in 2010.9
  • Only 17.3 percent of primary MDR TB cases were in U.S. born persons. The proportion of MDR TB cases continues to disproportionately affect foreign-born persons in the United States. This group accounted for 26 percent of MDR TB cases in 1993, but 82.7 percent of such cases in 2011.10
  • The World Health Organization estimates that there were about 310,000 cases of MDR TB worldwide in 2011, of which approximately 9.0 percent were extensively drug-resistant. XDR TB has been identified in 84 different countries.11
  • It is important to understand that there is a difference between being infected with TB and having TB disease. Someone who is infected with TB has the TB germs, or bacteria, in his/her body. The body's defenses, though, are protecting them from the germs, and they are not sick and cannot spread TB. This is called latent tuberculosis. A person with symptoms of TB disease or evidence of infection needs to be seen by a physician.
  • Several symptoms are associated with TB disease, including prolonged coughing (sometimes including coughing up of blood), repeated night sweats, unexplained weight loss, loss of appetite, fever, chills, and general lethargy.  Because these signs may be indicative of other diseases as well, a person must consult a physician to determine the cause of these symptoms.
  • The simplest way to find out if you have a TB infection is to get either a TB skin or blood test, widely available at clinics or at a doctors’ office. If either is significant, then you probably have TB infection and the doctor will run more tests, such as a chest x-ray, to determine whether you have active TB disease. 
    • The preferred skin test is the Mantoux test, in which a small amount of testing material is injected under the very top layers of skin on the forearm. In 48 to 72 hours the test is read by a trained person, usually a nurse or doctor. The skin test may be significant because of previous vaccination against TB. In some groups, such as the elderly or those with impaired immunity, the skin test may not be significant in the presence of TB infection.12
    • There are two blood tests available in the U.S. that the FDA has approved for the detection of active and latent TB. Blood is drawn and sent to a lab where the strength of the immune system’s response to the TB bacteria is measured to determine infection. Blood tests for TB may be preferred over the skin test for those vaccinated against TB or unable to return for a skin test reading.13
  • The recommended length of drug therapy for most types of TB is 6 to 9 months.14 Treatment for MDR TB is expensive and involves drug therapy over many months or years. Even with the longer course of treatment, the cure rate for MDR TB is approximately 50 percent, compared to over 90 percent for non-resistant strains of TB. XDR TB treatment is successful approximately 30 percent of the time for patients without compromised immune systems; it is even lower for those with compromised immune systems (such as those with HIV/AIDS).15
  • In 2008, 88 percent of TB patients completed therapy within 1 year, which was below the Health People 2010 target of 90 percent. Reasons patients did not complete therapy included moving, being lost track of, refusing to continue treatment, and dying.16 During 1993 to 2002, patients with XDR TB were 64 percent more likely to die or have treatment failure.17
  • Because it is difficult for some people to successfully complete their tuberculosis treatment, several innovations have been developed. The use of incentives and enablers has been popular with health departments and TB treatment centers. Examples include free transport to centers or food coupons which are given to patients each time they appear at the clinic or doctor's office for treatment. Incentives and enablers are combined with the use of directly observed therapy (DOT). DOT is a system of treatment in which the patient is administered his or her medication by a nurse or health worker whom "observes" the medication is taken.18

For more information on tuberculosis, please review the Tuberculosis Morbidity and Mortality Trend Report in the Data and Statistics section of our website at www.lung.org or call the American Lung Association at 1-800-LUNG-USA (1-800-586-4872).

 

Sources:

1.  Centers for Disease Control and Prevention. Reported Tuberculosis in the United States, 2011. October 2012.
2. Centers for Disease Control and Prevention. Emergence of Mycobacterium Tuberculosis with Extensive Resistance to Second-Line Drugs – Worldwide, 2000-2004. Morbidity and Mortality Weekly Report. March 24, 2006; 55(11):301-5.
3. Ibid.
4. Centers for Disease Control and Prevention. Reported Tuberculosis in the United States, 2011. October 2012.
5. Centers for Disease Control and Prevention. Tuberculosis in the United States: National Tuberculosis Surveillance System Highlights from 2011.
6. Centers for Disease Control and Prevention. Extensively Drug-Resistant Tuberculosis – United States, 1993-2006. Morbidity and Mortality Weekly Report. March 23, 2007; 57(11):281-5.
7. Centers for Disease Control and Prevention. Trends in Tuberculosis – United States, 2011. Morbidity and Mortality Weekly Report. March 23, 2012; 61(11):181-5.
8. Ibid.
9. Centers for Disease Control and Prevention. Reported Tuberculosis in the United States, 2011. October 2012.
10. Ibid.
11. World Health Organization. Global Tuberculosis Control Report, 2012.
12. American Thoracic Society and Centers for Disease Control and Prevention. Targeted Tuberculin Testing and Treatment of Latent Tuberculosis Infection. Morbidity and Mortality Weekly Report. June 9, 2000; 49(RR06):1-54.
13. Centers for Disease Control and Prevention. Division of Tuberculosis Elimination. Testing for Tuberculosis (TB). April 27, 2012.
14. American Thoracic Society, Centers for Disease Control and Prevention and Infectious Disease Society of America. Treatment of Tuberculosis. Morbidity and Mortality Weekly Report. June 20, 2003; 52(RR-11):1–77.
15. Castro, KC. Statement to Senate Committee on Health, Education, Labor and Pensions, October 30, 2007.
16. Centers for Disease Control and Prevention. Reported Tuberculosis in the United States, 2011. October 2012.
17. Centers for Disease Control and Prevention. Emergence of Mycobacterium Tuberculosis with Extensive Resistance to Second-Line Drugs – Worldwide, 2000-2004. Morbidity and Mortality Weekly Report. March 24, 2006; 55(11):301-5.
18. American Thoracic Society, CDC and Infectious Disease Society of America. Treatment of Tuberculosis. Morbidity and Mortality Weekly Report. June 20, 2003; 52(RR-11):1–77.