title: Evaluation of large genotypic Mycobacterium tuberculosis clusters: contributions from remote and recent transmission.
abstract: Tuberculosis genotypic clustering is used as a proxy for recent transmission. The association between clustering and recent transmission becomes problematic when the genotyping method lacks specificity in defining a cluster, as well as for clusters with extensive jurisdictional histories and/or common genotypes. We investigated the four largest spoligotype/12 loci MIRU-VNTR-defined clusters in Harris County, Texas from 2006-2012 to determine their historical contribution to tuberculosis morbidity, estimate the contributions from recent and remote transmission, and determine the impact of secondary genotyping on cluster definition. The clusters contained 189, 64, 51 and 38 cases. Each cluster was linked to cluster(s) previously identified by Houston Tuberculosis Initiative; 3 since 1995 and the fourth in 2002. Among cases for which timing of Mycobacterium tuberculosis transmission relative to tuberculosis disease could be ascertained, nearly equal proportions were associated with recent and remote transmission. The extent to which genotyping with an additional 12 MIRU-VNTR loci modified the cluster definition varied from little or no impact for the two smaller clusters to moderate impact for the larger clusters. Tuberculosis control measures to reduce morbidity associated with large clusters must involve strategies to identify and treat individuals who recently acquired infection, as well as persons infected for years.
authors.affiliation: Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Disease Research, Houston Methodist Research Institute, Houston, TX 77030, USA.
authors.forename: Larry D
authors.initials: LD
authors.lastname: Teeter
authors.affiliation: Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Disease Research, Houston Methodist Research Institute, Houston, TX 77030, USA.
authors.forename: Ngan P
authors.initials: NP
authors.lastname: Ha
authors.affiliation: Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Disease Research, Houston Methodist Research Institute, Houston, TX 77030, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Ma
authors.affiliation: Mycobacteriology and Mycology Section, Microbial Diseases Laboratory, Division of Communicable Disease Control, Center for Infectious Diseases, California Department of Public Health, Richmond, CA, USA.
authors.forename: Jane
authors.initials: J
authors.lastname: Wenger
authors.affiliation: Center for TB Control and Prevention, Maryland Department of Health and Mental Hygiene, Baltimore, MD 21202, USA.
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Cronin
authors.affiliation: Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Disease Research, Houston Methodist Research Institute, Houston, TX 77030, USA.
authors.forename: James M
authors.initials: JM
authors.lastname: Musser
authors.affiliation: Department of Pathology and Genomic Medicine, Center for Molecular and Translational Human Infectious Disease Research, Houston Methodist Research Institute, Houston, TX 77030, USA. Electronic address: eagraviss@houstonmethodist.org.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Graviss
mesh_terms: D000367:Age Factors; D015373:Bacterial Typing Techniques / Q000379:methods*; D004269:DNA, Bacterial; D019143:Evolution, Molecular; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D017720:Molecular Epidemiology; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D012923:Social Class; D013781:Texas; D014376:Tuberculosis / Q000453:epidemiology / Q000517:prevention & control / Q000635:transmission*; D014481:United States
chemical_list: D004269:DNA, Bacterial
keywords: Cluster; Epidemiology; Genotype; Transmission; Tuberculosis