title: Transmission of multidrug-resistant tuberculosis in the USA: a cross-sectional study.
abstract: BACKGROUND
  Multidrug-resistant (MDR) tuberculosis is a potential threat to tuberculosis elimination, but the extent of MDR tuberculosis disease in the USA that is attributable to transmission within the country is unknown. We assessed transmission of MDR tuberculosis and potential contributing factors in the USA.
  
  
  METHODS
  In a cross-sectional study, clinical, demographic, epidemiological, and Mycobacterium tuberculosis genotype data were obtained during routine surveillance of all verified cases of MDR tuberculosis reported from eight states in the USA (California from Jan 1, 2007, to Dec 31, 2009; Texas from Jan 1, 2007, to March 31, 2009; and the states of Colorado, Maryland, Massachusetts, New York, Tennessee, and Washington from Jan 1, 2007 to Dec 31, 2008). In-depth interviews and health-record abstraction were done for all who consented to ascertain potential interpersonal connections.
  
  
  RESULTS
  168 cases of MDR tuberculosis were reported in the eight states during our study period. 92 individuals (55%) consented to in-depth interview. 20 (22%) of these individuals developed MDR tuberculosis as a result of transmission in the USA; a source case was identified for eight of them (9%). 20 individuals (22%) had imported active tuberculosis (ie, culture-confirmed disease within 3 months of entry into the USA). 38 (41%) were deemed to have reactivation of disease, of whom 14 (15%) had a known previous episode of tuberculosis outside the USA. Five individuals (5%) had documented treatment of a previous episode in the USA, and so were deemed to have relapsed. For nine cases (10%), insufficient evidence was available to definitively classify reason for presentation.
  
  
  CONCLUSIONS
  About a fifth of cases of MDR tuberculosis in the USA can be linked to transmission within the country. Many individuals acquire MDR tuberculosis before entry into the USA. MDR tuberculosis needs to be diagnosed rapidly to reduce potential infectious periods, and clinicians should consider latent tuberculosis infection treatment-tailored to the results of drug susceptibility testing of the putative source case-for exposed individuals.
  
  
  BACKGROUND
  Centers for Disease Control and Prevention.
authors.affiliation: Division of Tuberculosis Elimination, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. pmoonan@cdc.gov
authors.forename: Patrick K
authors.initials: PK
authors.lastname: Moonan
authors.forename: Larry D
authors.initials: LD
authors.lastname: Teeter
authors.forename: Katya
authors.initials: K
authors.lastname: Salcedo
authors.forename: Smita
authors.initials: S
authors.lastname: Ghosh
authors.forename: Shama D
authors.initials: SD
authors.lastname: Ahuja
authors.forename: Jennifer
authors.initials: J
authors.lastname: Flood
authors.forename: Edward A
authors.initials: EA
authors.lastname: Graviss
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000995:Antitubercular Agents / Q000494:pharmacology; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005006:Ethnicity; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D018598:Minisatellite Repeats; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D012008:Recurrence; D011795:Surveys and Questionnaires; D013997:Time Factors; D014195:Travel; D018088:Tuberculosis, Multidrug-Resistant / Q000453:epidemiology / Q000635:transmission*; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents