title: Extensive transmission of an isoniazid-resistant strain of Mycobacterium tuberculosis in Sweden.
abstract: METHODS
  City of Stockholm, Sweden.
  
  
  BACKGROUND
  The incidence of tuberculosis (TB) in Sweden increased by 40% between 2003 and 2005. The spread of a unique TB strain resistant to isoniazid (INH) contributed to this increase.
  
  
  OBJECTIVE
  To describe outbreaks of TB caused by this single strain, elucidate possible causes for its extensive spread and identify shortcomings of the TB control programme in Sweden.
  
  
  RESULTS
  We identified a cluster consisting of 102 culture-confirmed TB cases with identical DNA fingerprints and 26 epidemiologically related cases, not confirmed by culture, all diagnosed between 1996 and 2005. Five partly separate outbreaks of this strain were discovered. Epidemiological links were established for 56% of the culture-confirmed cases and for all cases not confirmed by culture. Three patients died while receiving treatment, four became failures and eight defaulted or were lost to follow-up. Only eight patients received directly observed treatment (DOT) up to a period of 3 months, although 40% had poor adherence.
  
  
  CONCLUSIONS
  Shortcomings of the national TB programme were revealed. Improved contact tracing and case holding, including DOT, is crucial to reduce TB transmission in Sweden.
authors.affiliation: Infectious Diseases Unit, Department of Medicine, Karolinska Institutet, Karolinska University Hospital, Solna, Sweden. boris.kan@karolinska.se
authors.forename: B
authors.initials: B
authors.lastname: Kan
authors.forename: I
authors.initials: I
authors.lastname: Berggren
authors.forename: S
authors.initials: S
authors.lastname: Ghebremichael
authors.forename: R
authors.initials: R
authors.lastname: Bennet
authors.forename: J
authors.initials: J
authors.lastname: Bruchfeld
authors.forename: E
authors.initials: E
authors.lastname: Chryssanthou
authors.forename: G
authors.initials: G
authors.lastname: Källenius
authors.forename: R
authors.initials: R
authors.lastname: Petersson
authors.forename: B
authors.initials: B
authors.lastname: Petrini
authors.forename: V
authors.initials: V
authors.lastname: Romanus
authors.forename: S
authors.initials: S
authors.lastname: Sylvan
authors.forename: M
authors.initials: M
authors.lastname: Kalin
mesh_terms: D000293:Adolescent; D000328:Adult; D000995:Antitubercular Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D016000:Cluster Analysis; D016358:Contact Tracing; D016172:DNA Fingerprinting; D023801:Directly Observed Therapy; D004196:Disease Outbreaks / Q000517:prevention & control; D005260:Female; D006801:Humans; D007223:Infant; D007538:Isoniazid / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects* / Q000235:genetics; D013548:Sweden / Q000453:epidemiology; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy / Q000453:epidemiology* / Q000517:prevention & control / Q000635:transmission
chemical_list: D000995:Antitubercular Agents; D007538:Isoniazid