title: Conservation of purified protein derivative RT-23 tuberculin.
abstract: OBJECTIVE
  Recommendations that purified protein derivative (PPD) RT-23 tuberculin should not be kept and used more than 24 to 48 hours after opening are rarely complied with. The aim of this study was to determine whether using PPD RT-23 tuberculin from vials that had been open for a longer time could affect results of tuberculin tests and whether the solution could become contaminated.
  
  
  METHODS
  A prospective cross-sectional study was carried out. Two tuberculin tests were simultaneously administered, one in each forearm, to adult contacts of patients with active tuberculosis, one test using a recently opened vial of tuberculin (control) and the other using tuberculin that had been opened a week before (first phase) or a month before (second phase) (study tuberculin). Leftover tuberculin from several of the vials was cultured.
  
  
  RESULTS
  For the 127 patients in the first group (tuberculin opened 1 week), the mean (SD) diameter of the induration was 6.2 (6.9) mm for the study tuberculin and 6.3 (6.9) mm for the control (P=.3). For the 83 patients in the second group (tuberculin opened 1 month), the mean diameter of the induration was 5.5 (7.3) mm for the study tuberculin and 5.7 (7.3) mm for the control (P=.5). There were no differences between the number of positive tests found. None of the cultured tuberculins produced bacterial growth.
  
  
  CONCLUSIONS
  PPD RT-23 tuberculin does not appear to lose potency or sterility when vials have been opened for a week or a month.
authors.affiliation: Unidad de Tuberculosis de Vigo, Servicio de Neumología, Complejo Hospitalario Universitario Xeral-Cíes, Vigo, Joaquin Costa 60.6, 36004 Pontevedra, España. jfv01po@sakudalia.com
authors.forename: A
authors.initials: A
authors.lastname: Fernández-Villar
authors.forename: A
authors.initials: A
authors.lastname: Gorís
authors.forename: M
authors.initials: M
authors.lastname: Otero
authors.forename: N
authors.initials: N
authors.lastname: Chouciño
authors.forename: R
authors.initials: R
authors.lastname: Vázquez
authors.forename: M J
authors.initials: MJ
authors.lastname: Muñoz
authors.forename: L
authors.initials: L
authors.lastname: Piñeiro
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D004355:Drug Stability; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013997:Time Factors; D014373:Tuberculin; D014374:Tuberculin Test / Q000592:standards*
chemical_list: D014373:Tuberculin