10. MDR-TB

The emergence of multi drug-resistant tuberculosis (MDR-TB), defined as resistance to at least isoniazid and rifampicin, the two most important first line drugs, challenges global TB control. Extremely drug resistant TB (XDR), defined as MDR-TB with additional resistance to a fluoroquinolone and at least one of three injectable agents used in second line TB treatment (kanamycine, capreomycine, amikacine), increases the threat even more.

According to the WHO Global Tuberculosis Report 450 000 patients developped MDR-TB in 2012, and there were an estimated 170 000 deaths. By the end of 2012, 84 countries had reported at least one case of XDR. Coverage is low particularly in the African continent as a result of low capacity for testing for second-line medicines.

 

 

The figure above (from WHO global TB report 2013) shows the notified MDR-TB cases as a percentage of the estimated MDR-TB cases by country among the new and retreated TB cases notified in 2012. Over 60% of cases occur in China, India, the Russian Federation and South Africa alone.

HIV is common among drug-resistant (DR) TB patients, although no exact figures are known. HIV coinfection is a significant challenge for the prevention, diagnosis and treatment of DR-TB.

Case fatality rates are high for MDR-TB and even higher for XDR-TB, more so in HIV-coinfected patients. In a report from Kwa-Zulu Natal, 50% of the patients with HIV-MDR-TB co-infection died within 16 days after presentation.

Early diagnosis of DR-TB and HIV, prompt treatment with adequate regimens, sound patient support and strong infection control measures are all essential components in the management of DR-TB in HIV-infected people.

For more reading and practical tables see the WHO documents :
Guidelines for the programmatic management of drug-resistant tuberculosis. Emergency update, 2008;
Guidelines for the programmatic management of drug-resistant tuberculosis – 2011 update.