Multidrug Resistant TB - Definition, Epidemiology, Risk Factors

1. Definition
Epidemiology
Risk Factor
MDR TB

2. Definition
• The term "multi drug resistant TB" (MDR-TB) refers to an isolate of M. tuberculosis
that is resistant to at least isoniazid and rifampin and possibly additional
chemotherapeutic agents.
• The term "extensively drug resistant TB" (XDR-TB) refers to an isolate of M.
tuberculosis that is resistant to at least isoniazid, rifampin, and any fluoroquinolone
as well as either aminoglycosides (amikacin, kanamycin) or capreomycin or both .
• The term "totally drug resistant TB" (TDR-TB) refers to an isolate of M. tuberculosis
resistant to all locally tested medications. However, the published studies initially
describing TDRTB did not including susceptibility testing for less frequently used
agents with activity against TB, including cycloserine, terizidone, clofazimine,
linezolid, or carbapenems

3. Epidemiology
The WHO 2014 Global TB Report estimated that
•approximately 3.5 % of all new TB cases
•20.5 % of previously treated cases are MDR
•Roughly 480,000 cases of MDR TB Worldwide
•Highest number of cases in: China, India,
Russia, and the countries of the former Soviet
Union

7. Review Article
Indian J Med Res 120, October 2004, pp 354-376
Multidrug-resistant tuberculosis

8. Risk Factors
• Factors related to ATT:
» Doctor related
» Patient related
• Lack of good laboratory facilities
• Genetic factors: HLA DRB1*13 and
HLA DRB1*14
• HIV status

9. Factors related to ATT
• Doctor related:1
– addition of a single drug to a failing regimen
– failure to identify preexisting or acquired drug resistance
– initiation of an inadequate primary regimen
– failure to identify and address noncompliance and
inappropriate isoniazid preventive therapy
• Patient related:2
– travel to different places
– symptom relief
– adverse drug reactions
– inability to afford treatment
1. Mahmoudi A, Iseman MD. Pitfalls in the care of patients with tuberculosis. Common errors and their association with the acquisition of drug resistance.
JAMA 1993; 270 : 65-8.
2. Johnson J, Kagal A, Bharadwaj R. Factors associated with drug resistance in pulmonary tuberculosis. Indian J Chest Dis Allied Sci 2003; 45 : 105-9.

10. Reference
• Review Article: Indian J Med Res 120, October
2004, pp 354-376
S.K. Sharma & A. Mohan
• www.uptodate.com: Epidemiology and
molecular mechanisms of drug resistant
tuberculosis
Author: Neil W Schluger, MD
Section Editor: C Fordham von Reyn, MD
Deputy Editor: Elinor L Baron, MD, DTMH

11. That’s It