title: A geographically-restricted but prevalent Mycobacterium tuberculosis strain identified in the West Midlands Region of the UK between 1995 and 2008.
abstract: BACKGROUND
  We describe the identification of, and risk factors for, the single most prevalent Mycobacterium tuberculosis strain in the West Midlands region of the UK.
  
  
  RESULTS
  Prospective 15-locus MIRU-VNTR genotyping of all M. tuberculosis isolates in the West Midlands between 2004 and 2008 was undertaken. Two retrospective epidemiological investigations were also undertaken using univariable and multivariable logistic regression analysis. The first study of all TB patients in the West Midlands between 2004 and 2008 identified a single prevalent strain in each of the study years (total 155/3,056 (5%) isolates). This prevalent MIRU-VNTR profile (32333 2432515314 434443183) remained clustered after typing with an additional 9-loci MIRU-VNTR and spoligotyping. The majority of these patients (122/155, 79%) resided in three major cities located within a 40 km radius. From the apparent geographical restriction, we have named this the "Mercian" strain. A multivariate analysis of all TB patients in the West Midlands identified that infection with a Mercian strain was significantly associated with being UK-born (OR =  9.03, 95%CI = 4.56-17.87, p<0.01), Black Caribbean (OR = 5.68, 95%CI = 2.96-10.91, p < 0.01) resident in Wolverhampton (OR = 9.29, 95%CI = 5.69-15.19, p < 0.01) and negatively associated with age >65 years old (OR = 0.25, 95% CI = 0.09-0.67, p < 0.01). A second more detailed investigation analyzed a cohort of 82 patients resident in Wolverhampton between 2003 and 2006. A significant association with being born in the UK remained after a multivariate analysis (OR = 9.68, 95% CI = 2.00-46.78, p < 0.01) and excess alcohol intake and cannabis use (OR = 6.26, 95%CI = 1.45-27.02, p =  .01) were observed as social risk factors for infection.
  
  
  CONCLUSIONS
  The continued consistent presence of the Mercian strain suggests ongoing community transmission. Whilst significant associations have been found, there may be other common risk factors yet to be identified. Future investigations should focus on targeting the relevant risk groups and elucidating the biological factors that mediate continued transmission of this strain.
authors.affiliation: Health Protection Agency West Midlands Laboratory, Heart of England NHS Foundation Trust, Bordesley Green East, Birmingham, United Kingdom. jason.evans@heartofengland.nhs.uk
authors.forename: Jason T
authors.initials: JT
authors.lastname: Evans
authors.forename: Robert L
authors.initials: RL
authors.lastname: Serafino Wani
authors.forename: Laura
authors.initials: L
authors.lastname: Anderson
authors.forename: Andrea L
authors.initials: AL
authors.lastname: Gibson
authors.forename: E Grace
authors.initials: EG
authors.lastname: Smith
authors.forename: Annette
authors.initials: A
authors.lastname: Wood
authors.forename: Babatunde
authors.initials: B
authors.lastname: Olowokure
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Abubakar
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Mann
authors.forename: Sarah
authors.initials: S
authors.lastname: Gardiner
authors.forename: Helen
authors.initials: H
authors.lastname: Jones
authors.forename: Pam
authors.initials: P
authors.lastname: Sonnenberg
authors.forename: Peter M
authors.initials: PM
authors.lastname: Hawkey
mesh_terms: D002947:Cities / Q000453:epidemiology; D003710:Demography; D005843:Geography; D006801:Humans; D015994:Incidence; D018598:Minisatellite Repeats / Q000235:genetics; D015999:Multivariate Analysis; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000302:isolation & purification*; D012150:Polymorphism, Restriction Fragment Length; D015995:Prevalence; D015203:Reproducibility of Results; D014376:Tuberculosis / Q000453:epidemiology / Q000382:microbiology; D006113:United Kingdom / Q000453:epidemiology