title: Fitness of Mycobacterium tuberculosis strains of the W-Beijing and Non-W-Beijing genotype.
abstract: BACKGROUND
  Multidrug resistant tuberculosis (MDR-TB) is a major threat for global tuberculosis control. The W-Beijing Mycobacterium tuberculosis genotype has been associated with drug resistance. Elucidation of the mechanisms underlying this epidemiological finding may have an important role in the control of MDR-TB. The aim of this study was to evaluate the fitness of drug-susceptible and MDR M. tuberculosis strains of the W-Beijing genotype compared with that of Non-W-Beijing strains.
  
  
  RESULTS
  Fitness of M. tuberculosis strains was determined by evaluating the difference in the growth curves obtained in the MGIT960 automated system and assessing the competitive growth capacity between W-Beijing and non-W-Beijing strains. The W-Beijing MDR strains had a significant longer lag phase duration compared to the other strains but did not present a significant fitness cost. When grown in competition they had an advantage only in medium containing 0.1% Tween 80.
  
  
  CONCLUSIONS
  It was not possible to confirm a selective advantage of W-Beijing strains to grow, except for differences in their resistance to Tween 80. Further studies are needed to elucidate the putative advantage of W-Beijing strains compared to other genotypes.
authors.affiliation: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium. avongrol@hotmail.com
authors.forename: Andrea
authors.initials: A
authors.lastname: von Groll
authors.forename: Anandi
authors.initials: A
authors.lastname: Martin
authors.forename: Matthias
authors.initials: M
authors.lastname: Stehr
authors.forename: Mahavir
authors.initials: M
authors.lastname: Singh
authors.forename: Françoise
authors.initials: F
authors.lastname: Portaels
authors.forename: Pedro Eduardo Almeida
authors.initials: PE
authors.lastname: da Silva
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Palomino
mesh_terms: D015373:Bacterial Typing Techniques; D024901:Drug Resistance, Multiple, Bacterial; D005838:Genotype; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000254:growth & development*