editors

MIGLIORI et al. [1] have written a commendable editorial about the challenges to science presented by the emergence of extensively drug-resistant tuberculosis (XDR-TB) as a named entity. We wish to clarify the origin and development of the term ‘‘XDR-TB’’. As noted by MIGLIORI et al. [1], resistance to second-line drugs is not a new phenomenon. Despite years of anecdotal reports about ‘‘super bugs’ ’ and TB strains (predominantly in the former Soviet Union and Asia) with resistance to six, seven and eight or more anti-TB drugs, the global distribution of TB strains with concurrent resistance to multiple second-line drugs had not been previously reported. The concept and term XDR-TB as a distinct nosological entity were first developed by the Centers for Disease Control and Prevention (CDC) in March 2005 and were introduced int