title: Mycobacterium tuberculosis Beijing strains favor transmission but not drug resistance in China.
abstract: BACKGROUND
  The Mycobacterium tuberculosis Beijing strains are widespread globally. We aimed to determine whether Beijing strains in China are more likely than other strains to spread, and whether they are more likely to become drug resistant. We also sought to determine whether different Beijing sublineages have distinct phenotypic characteristics.
  
  
  METHODS
  We conducted a population-based molecular epidemiologic study in 6 provinces in China from 2009 to 2010. We analyzed data and specimens from culture-confirmed pulmonary tuberculosis patients. Each patient's isolate was genotyped using 16-loci variable number of tandem repeats and 6 single-nucleotide polymorphisms.
  
  
  RESULTS
  By genotyping, 75.0% (1031/1375) of the strains of M. tuberculosis were Beijing strains. Beijing strains were more likely than non-Beijing strains to be in a genotypic cluster (odds ratio, 2.40, P < .001), and were significantly associated with younger age (P(trend) < .05). There was no significant difference in the proportion of Beijing strains and non-Beijing strains that were drug resistant, even when stratified by new vs retreatment patients. We identified 6 sublineages of Beijing strains in the study population. The modern sublineage of Beijing strains were more likely than the ancient sublineages to be clustered (odds ratio, 2.27, P < .001).
  
  
  CONCLUSIONS
  Beijing strains of M. tuberculosis were significantly associated with genotypic clustering, reflecting recent transmission, and younger age, but were not associated with drug resistance. Future studies of Beijing family strains should avoid assuming and attributing characteristics to the entire family and should assess strains of specific sublineages and/or settings.
authors.affiliation: Key Laboratory of Medical Molecular Virology, Institutes of Biomedical Sciences and Institute of Medical Microbiology, Fudan University, 138 Yi Xue Yuan Road, Shanghai, China.
authors.forename: Chongguang
authors.initials: C
authors.lastname: Yang
authors.forename: Tao
authors.initials: T
authors.lastname: Luo
authors.forename: Guomei
authors.initials: G
authors.lastname: Sun
authors.forename: Ke
authors.initials: K
authors.lastname: Qiao
authors.forename: Gang
authors.initials: G
authors.lastname: Sun
authors.forename: Kathryn
authors.initials: K
authors.lastname: DeRiemer
authors.forename: Jian
authors.initials: J
authors.lastname: Mei
authors.forename: Qian
authors.initials: Q
authors.lastname: Gao
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000494:pharmacology*; D002681:China / Q000453:epidemiology; D016000:Cluster Analysis; D024881:Drug Resistance, Bacterial; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D018598:Minisatellite Repeats; D017720:Molecular Epidemiology; D058889:Molecular Typing; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D020641:Polymorphism, Single Nucleotide; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000382:microbiology* / Q000635:transmission; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents