Multidrug-Resistant Tuberculosis

Posted by Graham McMahon • September 10th, 2010

The latest article in our Current Concepts review series, “MDR Tuberculosis — Critical Steps for Prevention and Control,” comes from the Stop TB Department at the World Health Organization in Geneva.

Multidrug-resistant (MDR) tuberculosis is defined as disease caused by strains of Mycobacterium tuberculosis that are at least resistant to treatment with isoniazid and rifampicin. Extensively drug-resistant (XDR) tuberculosis refers to disease caused by multidrug-resistant strains that are also resistant to treatment with any fluoroquinolone and any of the injectable drugs used in second-line treatment of tuberculosis (amikacin, capreomycin, and kanamycin).

Clinical Pearls

What is the global epidemiology of MDR tuberculosis?

In 2008, an estimated 440,000 cases of MDR tuberculosis emerged globally. India and China carry the greatest estimated burden of MDR tuberculosis, together accounting for almost 50% of the world’s total cases. In some countries, the incidence of tuberculosis is rising, and the incidence of MDR tuberculosis appears to be rising even faster (e.g., in Botswana and South Korea). The highest proportions of MDR cases, and the most severe drug-resistance patterns, appear in the countries of the former Soviet Union.

What is the approximate cost of second-line anti-tuberculosis drug treatment?

In virtually all countries with a high burden of MDR tuberculosis, treatment costs for one person are more than 100% of the gross national income per capita. The cost of second-line anti-tuberculosis drugs alone is typically $2,000 to $4,000 per patient.

Morning Report Questions

Q: What is the WHO-recommended Stop TB strategy?

A: The WHO-recommended Stop TB Strategy provides the framework for treatment, care, and control of drug-susceptible and drug-resistant disease. The directly observed treatment (DOTS) approach, which underpins the Stop TB Strategy, calls for political commitment to control disease by means of early diagnosis with the use of bacteriologic testing, standardized treatment with supervision and patient support, and provision and management of the drugs used in treatment, as well as monitoring of treatment and evaluation of its effectiveness.

Q: Are health care workers at increased risk of contracting MDR tuberculosis?

A: Health care workers, especially those working in tuberculosis hospitals and in resource-limited settings, are at substantially higher risk of contracting tuberculosis and MDR tuberculosis than the general population. All health care facilities that admit patients with tuberculosis or patients suspected of having tuberculosis should implement tuberculosis-control measures that complement general measures of infection control, especially those which target other airborne infections.

Table 1. Critical Challenges in the Control of MDR Tuberculosis and XDR Tuberculosis and Potential Solutions Supported by the WHO.

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