title: Tuberculosis in healthcare workers: a molecular epidemiologic study in San Francisco.
abstract: OBJECTIVE
  Healthcare workers (HCWs) are at risk of becoming infected with Mycobacterium tuberculosis through occupational exposure. To identify HCWs who became infected and developed tuberculosis as a result of their work, we studied the molecular epidemiology of tuberculosis in HCWs.
  
  
  METHODS
  Eleven-year prospective cohort molecular epidemiology study.
  
  
  METHODS
  City and County of San Francisco, California.
  
  
  METHODS
  All persons reported with tuberculosis between 1993 and 2003. HCWs were identified from the San Francisco Tuberculosis Control Section's database, and mycobacterial isolates from culture-positive subjects were analyzed by IS6110-based genotyping.
  
  
  RESULTS
  Of 2510 cases of tuberculosis reported during the study period, 31 (1.2%) occurred in HCWs: the median age of the HCWs was 37 years, and 11 (35%) were male. HCWs were more likely than non-HCWs to be younger (P=.0036), born in the United States (P=.0004), and female (P=.0003) and to not be homeless (P=.010). The rate of tuberculosis among HCWs remained constant during the study period, despite a significant decrease in the overall case rate in San Francisco. Work-related transmission was documented in at least 10 (32%) of 31 HCWs, including 4 of 8 HCWs whose isolates were part of genotypically determined clusters. Only 1 of 7 cases of tuberculosis in HCWs after 1999 was documented as being work-related.
  
  
  CONCLUSIONS
  Although most cases of tuberculosis in HCWs, as in non-HCWs, developed as a result of endogenous reactivation of latent infection, at least half of clustered cases of tuberculosis in HCWs were related to work. The number of work-related cases of tuberculosis in HCWs decreased during the study period.
authors: Division of Pulmonary and Critical Care Medicine, San Francisco General Hospital, University of California, San Francisco, CA, USA.
authors: Adrian
authors: A
authors: Ong
authors: Irina
authors: I
authors: Rudoy
authors: Leah C
authors: LC
authors: Gonzalez
authors: Jennifer
authors: J
authors: Creasman
authors: L Masae
authors: LM
authors: Kawamura
authors: Charles L
authors: CL
authors: Daley