title: Challenges and controversies in defining totally drug-resistant tuberculosis.
abstract: In March 2012, in response to reports of tuberculosis (TB) resistant to all anti-TB drugs, the World Health Organization convened an expert consultation that identified issues to be resolved before defining a new category of highly drug-resistant TB. Proposed definitions are ambiguous, and extensive drug resistance is encompassed by the already defined extensively drug-resistant (XDR) TB. There is no evidence that proposed totally resistant TB differs from strains encompassed by XDR TB. Susceptibility tests for several drugs are poorly reproducible. Few laboratories can test all drugs, and there is no consensus list of all anti-TB drugs. Many drugs are used off-label for highly drug resistant TB, and new drugs formulated to combat resistant strains would render the proposed category obsolete. Labeling TB strains as totally drug resistant might lead providers to think infected patients are untreatable. These challenges must be addressed before defining a new category for highly drug-resistant TB.
authors.affiliation: Centers for Disease Control and Prevention, Atlanta, Georgia, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Cegielski
authors.forename: Paul
authors.initials: P
authors.lastname: Nunn
authors.forename: Ekaterina V
authors.initials: EV
authors.lastname: Kurbatova
authors.forename: Karin
authors.initials: K
authors.lastname: Weyer
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Dalton
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Wares
authors.forename: Michael F
authors.initials: MF
authors.lastname: Iademarco
authors.forename: Kenneth G
authors.initials: KG
authors.lastname: Castro
authors.forename: Mario
authors.initials: M
authors.lastname: Raviglione
mesh_terms: D006801:Humans; D009626:Terminology as Topic; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy