title: Molecular epidemiology of Mycobacterium tuberculosis among South African gold miners.
abstract: BACKGROUND
  HIV-associated tuberculosis remains a major health problem among the gold-mining workforce in South Africa. We postulate that high levels of recent transmission, indicated by strain clustering, are fueling the tuberculosis epidemic among gold miners.
  
  
  OBJECTIVE
  To combine molecular and epidemiologic data to describe Mycobacterium tuberculosis genetic diversity, estimate levels of transmission, and examine risk factors for clustering.
  
  
  METHODS
  We conducted a cross-sectional study of culture-positive M. tuberculosis isolates in 15 gold mine shafts across three provinces in South Africa. All isolates were subject IS6110-based restriction fragment length polymorphisms, and we performed spoligotyping analysis and combined it with basic demographic and clinical information.
  
  
  RESULTS
  Of the 1,602 M. tuberculosis patient isolates, 1,240 (78%) had genotyping data available for analysis. A highly diverse bacillary population was identified, comprising a total of 730 discrete genotypes. Four genotypic families (Latin American Mediterranean spoligotype family; W-Beijing; AH or X; and T1-T4) accounted for over 50% of all strains. Overall, 45% (560/1,240) of strains were genotypically clustered. The minimum estimate for recent transmission (n - 1 method) was 32% (range, 27-34%). There were no individual-level risk factors for clustering, apart from borderline evidence for being non-South African and having self-reported HIV infection.
  
  
  CONCLUSIONS
  The high M. tuberculosis genetic diversity and lack of risk factors for clustering are indicative of a universal risk for disease among gold miners and likely mixing with nonmining populations. Our results underscore the urgent need to intensify interventions to interrupt transmission across the entire gold-mining workforce in South Africa.
authors.affiliation: 1 Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York.
authors.forename: Barun
authors.initials: B
authors.lastname: Mathema
authors.forename: James J
authors.initials: JJ
authors.lastname: Lewis
authors.forename: Jeremy
authors.initials: J
authors.lastname: Connors
authors.forename: Violet N
authors.initials: VN
authors.lastname: Chihota
authors.forename: Elena
authors.initials: E
authors.lastname: Shashkina
authors.forename: Minty
authors.initials: M
authors.lastname: van der Meulen
authors.forename: Edward A
authors.initials: EA
authors.lastname: Graviss
authors.forename: Ngan P
authors.initials: NP
authors.lastname: Ha
authors.forename: Barry N
authors.initials: BN
authors.lastname: Kreiswirth
authors.forename: Alison D
authors.initials: AD
authors.lastname: Grant
authors.forename: Katherine L
authors.initials: KL
authors.lastname: Fielding
authors.forename: Susan E
authors.initials: SE
authors.lastname: Dorman
authors.forename: Gavin J
authors.initials: GJ
authors.lastname: Churchyard
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D004269:DNA, Bacterial / Q000235:genetics*; D005260:Female; D005838:Genotype; D006046:Gold; D006801:Humans; D015994:Incidence; D008297:Male; D008906:Mining; D017720:Molecular Epidemiology / Q000379:methods*; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification; D012150:Polymorphism, Restriction Fragment Length; D013019:South Africa / Q000453:epidemiology; D014376:Tuberculosis / Q000453:epidemiology* / Q000382:microbiology
chemical_list: D004269:DNA, Bacterial; D006046:Gold
keywords: South Africa; gold mines; molecular epidemiology; tuberculosis