title: From multidrug- to extensively drug-resistant tuberculosis: upward trends as seen from a 15-year nationwide study.
abstract: BACKGROUND
  Emergence of extensively drug-resistant tuberculosis (XDR-TB) represents an enormous challenge to Public Health globally.
  
  
  METHODS
  Progression towards XDR-TB was investigated in Belgium, a country with a typically low TB incidence, by analyzing the magnitude, characteristics, and treatment success of multidrug-resistant tuberculosis (MDR-TB) through a population-based study from 1994 to 2008.
  
  
  RESULTS
  Among the 174 MDR-TB patients, 81% were foreign-born, 48% of these being asylum seekers. Although the number of MDR-TB patients remained stable through the study period at around 15 new cases annually, frequencies of resistance of the patients' first MDR-TB isolate to second-line drugs increased, as well as the total number of antibiotics it was resistant to (p<0.001). XDR-TB cases were detected from 2002 onwards. For 24 patients, additional resistance to several second-line drugs was acquired during treatment. Molecular-guided investigations indicated little to no contribution of in-country clonal spread or exogenous re-infection. The increase of pre-XDR and XDR cases could be attributed to rising proportions of patients from Asia and Central and Eastern Europe (p<0.001) and an increase in the isolation of Beijing strains in these groups (p<0.001). Despite augmented resistance, the treatment success rate improved from 63.0% to 75.8% (p = 0.080) after implementation in 2005 of improved surveillance measures and therapeutic access.
  
  
  CONCLUSIONS
  Increasing severity in drug resistance patterns leading to more XDR- and "panresistant" TB cases in a country with a low TB incidence like Belgium represents a strong alert on worsening situations in other world regions and requires intense public health measures.
authors.affiliation: National Reference Centre of Tuberculosis and Mycobacteria, Communicable and Infectious Diseases, Scientific Institute of Public Health, Brussels, Belgium.
authors.forename: Karolien
authors.initials: K
authors.lastname: Stoffels
authors.forename: Caroline
authors.initials: C
authors.lastname: Allix-Béguec
authors.forename: Guido
authors.initials: G
authors.lastname: Groenen
authors.forename: Maryse
authors.initials: M
authors.lastname: Wanlin
authors.forename: Dirk
authors.initials: D
authors.lastname: Berkvens
authors.forename: Vanessa
authors.initials: V
authors.lastname: Mathys
authors.forename: Philip
authors.initials: P
authors.lastname: Supply
authors.forename: Maryse
authors.initials: M
authors.lastname: Fauville-Dufaux
mesh_terms: D000293:Adolescent; D000328:Adult; D000995:Antitubercular Agents / Q000627:therapeutic use; D001530:Belgium / Q000453:epidemiology; D054908:Extensively Drug-Resistant Tuberculosis / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D005260:Female; D006306:Health Surveys / Q000379:methods* / Q000706:statistics & numerical data* / Q000639:trends; D006801:Humans; D015994:Incidence; D008297:Male; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000302:isolation & purification; D012042:Registries / Q000706:statistics & numerical data; D016896:Treatment Outcome; D018088:Tuberculosis, Multidrug-Resistant / Q000188:drug therapy / Q000453:epidemiology* / Q000382:microbiology; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents