title: [Number of concentrated sputum smears needed to adequately assess infectivity of patients with pulmonary tuberculosis].
abstract: OBJECTIVE
  Investigating the usefulness of 3rd concentrated sputum smear for assessments of infectivity of pulmonary tuberculosis patients.
  
  
  OBJECTIVE
  Retrospective study of the results of diagnostic 3 consecutive concentrated-sputum-smear (fluorochrome stain) of culture-proven pulmonary tuberculosis cases at our hospital from Jan. 2002 to Sep. 2003.
  
  
  RESULTS
  Altogether 362 cases were available for analysis, and 306 (84.0%) cases were smear-positive on 3 consecutive sputum tests. Of these cases, 26 cases (8.6% of smear-positive cases) were firstly smear-positive by the 3rd sputum. Of 278 cases that were already smear-positive at first and/or second sputum smear, 40 cases (13.2% of smear-positive cases) showed the highest smear-positive grade at 3rd sputum-smear, but only 6 cases (2.0% of smear-positive cases) had smear-positive grade higher by two-grade (+/- to more than 2+, or 1+ to 3+).
  
  
  CONCLUSIONS
  From the results of this study together with literature review, sensitivity of 2 concentrated sputum-smear tests by fluorochrome stain is presumed to be same as, or better than that of 3 direct sputum-smear tests by Ziehl-Neelsen stain. We have to re-consider the number of concentrated sputum smear tests needed to assess the infectivity of pulmonary tuberculosis.
authors.affiliation: Correspondence to: Kunihiko Ito, Department of Research, Research Institute of Tuberculosis, JATA, 3-1-24, Matsuyama, Kiyose-shi, Tokyo 204-8533 Japan. ito@jata.or.jp
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Ito
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001431:Bacteriological Techniques / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000382:microbiology*