title: Increase in tuberculin skin test converters among health care workers after a change from Tubersol to Aplisol.
abstract: BACKGROUND
  Comparability of the 2 commercially available tuberculin skin testing (TST) preparations, Aplisol (Parkdale Pharmaceuticals, Inc, Rochester, MI) and Tubersol (Aventis Pasteur, Inc, Swiftwater, PA), remains uncertain, particularly in groups that undergo repeated testing, such as health care workers.
  
  
  METHODS
  Data from the annual tuberculosis screening program for health care workers at the Kennedy Krieger Institute in Baltimore, Maryland, were analyzed. Conversion rates during 1997-2003 in workers screened with Tubersol (n = 8897 screenings) were compared with 1203 workers who underwent screening with Aplisol in 2004. Repeat testing with Tubersol was examined in those who converted in 2004 with Aplisol.
  
  
  RESULTS
  Annual TST conversion rates ranged from 0.3% to 0.9% between 1997 and 2003 using Tubersol. After switching to Aplisol in 2004, the TST conversion rate significantly increased to 2% (P < .001). Among 24 health care workers who were converters with Aplisol in 2004, only 6 of 23 (26%) were converters on repeat testing with Tubersol (1 declined retesting). None of the apparent converters (n = 24) had radiographic evidence of Mycobacterium tuberculosis infection, and there was no epidemiologic evidence of transmission. Reclassification based on Tubersol testing in 2004 resulted in conversion rates comparable with previous years.
  
  
  CONCLUSIONS
  We conclude that the change from Tubersol to Aplisol resulted in falsely elevated conversion rates. Our results support the guidelines from the Centers for Disease Control and Prevention recommendations that 1 product should be used consistently in populations undergoing periodic testing.
authors.affiliation: Department of Pediatrics, Johns Hopkins Medical Institutions, 200 N. Wolfe Street, Baltimore, MD 21287, USA.
authors.forename: Kari A
authors.initials: KA
authors.lastname: Gillenwater
authors.forename: Sandra C
authors.initials: SC
authors.lastname: Sapp
authors.forename: Kim
authors.initials: K
authors.lastname: Pearce
authors.forename: George K
authors.initials: GK
authors.lastname: Siberry
mesh_terms: D000328:Adult; D015142:Baltimore / Q000453:epidemiology; D017046:Cost Savings; D018592:Cross-Over Studies; D016527:Drug Costs / Q000706:statistics & numerical data; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006776:Hospitals, Pediatric; D006801:Humans; D017053:Infection Control; D008297:Male; D008403:Mass Screening / Q000191:economics / Q000379:methods; D009784:Occupational Diseases / Q000175:diagnosis / Q000453:epidemiology; D009786:Occupational Health Services; D010564:Personnel, Hospital / Q000706:statistics & numerical data*; D017410:Practice Guidelines as Topic; D012047:Rehabilitation Centers; D014373:Tuberculin / Q000191:economics; D014374:Tuberculin Test / Q000191:economics / Q000379:methods*; D014376:Tuberculosis / Q000175:diagnosis / Q000453:epidemiology
chemical_list: D014373:Tuberculin