Worldwide Emergence of Extensively Drug-resistant Tuberculosis

TLDR

Extensively drug-resistant Mycobacterium tuberculosis strains, resistant to multiple second‑line drugs, pose a growing global public health threat, underscoring the need for population‑based surveillance and enhanced prevention and treatment strategies. The authors surveyed 23 supranational reference laboratories from 2000 to 2004, collecting data on isolates resistant to second‑line drugs, and defined XDR TB as MDR TB with resistance to three or more of six second‑line drug classes. Data from 14 laboratories covering 48 countries yielded 17,690 isolates, of which 3,520 (19.9 %) were MDR TB and 347 (9.9 %) met the XDR TB definition.

Abstract

Mycobacterium tuberculosis strains that are resistant to an increasing number of second-line drugs used to treat multidrug-resistant tuberculosis (MDR TB) are becoming a threat to public health worldwide. We surveyed the Network of Supranational Reference Laboratories for M. tuberculosis isolates that were resistant to second-line anti-TB drugs during 2000-2004. We defined extensively drug-resistant TB (XDR TB) as MDR TB with further resistance to > or = 3 of the 6 classes of second-line drugs. Of 23 eligible laboratories, 14 (61%) contributed data on 17,690 isolates, which reflected drug susceptibility results from 48 countries. Of 3,520 (19.9%) MDR TB isolates, 347 (9.9%) met criteria for XDR TB. Further investigation of population-based trends and expanded efforts to prevent drug resistance and effectively treat patients with MDR TB are crucial for protection of public health and control of TB.