Extensively drug-resistant (XDR) tuberculosis: an old and new threat

Abstract

Tuberculosis (TB) remains a worldwide emergency (8 million new cases per year, 2 million deaths annually) mostly affecting poor countries. To this old, persistent threat, a new emergency is adding further challenge, i.e., the multidrug-resistant TB, which in its extreme and highly lethal form is called XDR TB (extensively drug-resistant TB). How to fight XDR TB is a high research and public health priority.