title: Shared Mycobacterium avium genotypes observed among unlinked clinical and environmental isolates.
abstract: Our understanding of the sources of Mycobacterium avium infection is partially based on genotypic matching of pathogen isolates from cases and environmental sources. These approaches assume that genotypic identity is rare in isolates from unlinked cases or sources. To test this assumption, a high-resolution PCR-based genotyping approach, large-sequence polymorphism (LSP)-mycobacterial interspersed repetitive unit-variable-number tandem repeat (MIRU-VNTR), was selected and used to analyze clinical and environmental isolates of M. avium from geographically diverse sources. Among 127 clinical isolates from seven locations in North America, South America, and Europe, 42 genotypes were observed. Among 12 of these genotypes, matches were seen in isolates from apparently unlinked patients in two or more geographic locations. Six of the 12 were also observed in environmental isolates. A subset of these isolates was further analyzed by alternative strain genotyping methods, pulsed-field gel electrophoresis and MIRU-VNTR, which confirmed the existence of geographically dispersed strain genotypes. These results suggest that caution should be exercised in interpreting high-resolution genotypic matches as evidence for an acquisition event.
authors.affiliation: University of Washington, Seattle, Washington, USA. madirac@uw.edu
authors.forename: M Ashworth
authors.initials: MA
authors.lastname: Dirac
authors.forename: Kris M
authors.initials: KM
authors.lastname: Weigel
authors.forename: Mitchell A
authors.initials: MA
authors.lastname: Yakrus
authors.forename: Annie L
authors.initials: AL
authors.lastname: Becker
authors.forename: Hui-Ling
authors.initials: HL
authors.lastname: Chen
authors.forename: Gina
authors.initials: G
authors.lastname: Fridley
authors.forename: Arthur
authors.initials: A
authors.lastname: Sikora
authors.forename: Cate
authors.initials: C
authors.lastname: Speake
authors.forename: Elizabeth D
authors.initials: ED
authors.lastname: Hilborn
authors.forename: Stacy
authors.initials: S
authors.lastname: Pfaller
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Cangelosi
mesh_terms: D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004783:Environmental Microbiology; D005060:Europe; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D058889:Molecular Typing / Q000379:methods*; D009162:Mycobacterium avium / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D009656:North America; D017422:Sequence Analysis, DNA; D013020:South America; D014376:Tuberculosis / Q000453:epidemiology* / Q000382:microbiology*
chemical_list: D004269:DNA, Bacterial