Identification of a W variant outbreak of Mycobacterium tuberculosis via population-based molecular epidemiology

JAMA. 1999 Dec;282(24):2321-7. doi: 10.1001/jama.282.24.2321.


Context: Typing of Mycobacterium tuberculosis could provide a more sensitive means of identifying outbreaks than use of conventional surveillance techniques alone. Variants of the New York City W strain of M tuberculosis were identified in New Jersey.

Objective: To describe the spread of the W family of M tuberculosis strains in New Jersey identified by molecular typing and surveillance data.

Design: Population-based cross-sectional study.

Setting and subjects: All incident culture-positive tuberculosis cases reported in New Jersey from January 1996 to September 1998, for which the W family was defined by insertion sequence (IS) IS6110 DNA fingerprinting, polymorphic GC-rich repetitive sequence (PGRS) typing, spacer oligotyping (spoligotyping), and variable number tandem repeat (VNTR) analysis.

Main outcome measure: Identification and characterization of W family clones supplemented by surveillance data.

Results: Isolates from 1207 cases were analyzed, of which 68 isolates (6%) belonged to the W family based on IS6110 and spoligotype hybridization patterns. The IS6110 hybridization patterns or fingerprints revealed that43 patients (designated group A) shared a unique banding motif not present in other W family isolates. Strains collected from the remaining 25 patients (designated group B), while related to W, displayed a variety of IS6110 patterns and did not share this motif. The PGRS and VNTR typing confirmed the division of the W family into groups A and B and again showed group A strains to be closely related and group B strains to be more diverse. The demographic characteristics of individuals from groups A and B were specific and defined. Group A patients were more likely than group B patients to be US born (91 % vs 24%, P<.001), black (76% vs 16%, P<.001), human immunodeficiency virus positive (40% vs 0%, P = .007), and residents of urban northeast New Jersey counties (P<.001). Patients with group B strains were primarily non-US born, of Asian descent, and more dispersed throughout New Jersey. No outbreak had been detected using conventional surveillance alone.

Conclusions: The implementation of multiple molecular techniques in conjunction with surveillance data enabled us to identify a previously undetected outbreak in a defined geographical setting. The outbreak isolates comprise members of a distinct branch of the W family phylogenetic lineage. The use of molecular strain typing provides a proactive approach that may be used to initiate, and not just augment, traditional surveillance outbreak investigations.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Bacterial Typing Techniques
  • Blotting, Southern
  • Cross-Sectional Studies
  • DNA Fingerprinting*
  • DNA, Bacterial / analysis*
  • Disease Outbreaks*
  • Female
  • Genotype
  • Humans
  • Male
  • Molecular Epidemiology
  • Mycobacterium tuberculosis / classification
  • Mycobacterium tuberculosis / genetics*
  • New Jersey / epidemiology
  • New York / epidemiology
  • Population Surveillance
  • Repetitive Sequences, Nucleic Acid
  • Tuberculosis / epidemiology*
  • Tuberculosis / microbiology


  • DNA, Bacterial