title: Long-term molecular analysis of tuberculosis strains in alabama, a state characterized by a largely indigenous, low-risk population.
abstract: With a tuberculosis case detection rate of 5.9 per 100,000 population in 2001, Alabama ranked twelfth highest in the United States. However, cases among foreign-born and human immunodeficiency virus-infected individuals remain low in Alabama. To understand the endemic statewide disease pattern, tuberculosis strains were studied for clustering in a long-term population-based study from January 1994 to May 2000. IS6110 restriction fragment length polymorphism analysis was performed for 1,834 strains. Spoligotyping was used as a secondary typing method for the 37% of isolates displaying a restriction fragment length polymorphism pattern with <6 IS6110 copies. A total of 721 (41%) patients provided isolates that composed 114 clusters, each containing isolates from 2 to 136 patients, suggesting that recent transmission accounted for 35% of tuberculosis cases. Demographic, behavioral, and clinical characteristics of patients with clustered versus nonclustered isolates stratified by low-copy-number strains (<6 IS6110 copies) versus high-copy-number strains (> or =6 IS6110 copies) were evaluated. Younger age, black race, a history of alcohol abuse, and homelessness were predictors of clustering of low-copy-number, strains and younger age, urban residency, alcohol abuse, homelessness, noninjection drug use, and a history of incarceration and/or cavitary disease were predictors of clustering of high-copy-number strains. By identifying local characteristics of tuberculosis clustering through molecular fingerprinting, control programs can distribute their limited resources to impact the transmission of tuberculosis in high-risk populations and evaluate strain distribution across geographical areas.
authors.affiliation: Division of Pulmonary and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA. Mkempf@uab.edu
authors.forename: Mirjam-Colette
authors.initials: MC
authors.lastname: Kempf
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Dunlap
authors.forename: Kerry H
authors.initials: KH
authors.lastname: Lok
authors.forename: William H
authors.initials: WH
authors.lastname: Benjamin
authors.forename: Nancy B
authors.initials: NB
authors.lastname: Keenan
authors.forename: Michael E
authors.initials: ME
authors.lastname: Kimerling
mesh_terms: D000328:Adult; D000368:Aged; D000407:Alabama / Q000453:epidemiology; D015373:Bacterial Typing Techniques; D016000:Cluster Analysis; D004251:DNA Transposable Elements; D005260:Female; D018628:Gene Dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D009169:Mycobacterium tuberculosis / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D012150:Polymorphism, Restriction Fragment Length; D012307:Risk Factors; D013997:Time Factors; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission
chemical_list: D004251:DNA Transposable Elements