title: Are two sputum samples enough for diagnosing pulmonary tuberculosis.
abstract: OBJECTIVE
  To determine the optimum number of sputum specimens for smear and culture in the diagnosis of pulmonary tuberculosis.
  
  
  METHODS
  A retrospective study was conducted in culture-positive pulmonary tuberculosis patients at Siriraj Hospital during April 2009 to October 2010. Number of sputum specimens and microbiological results were retrieved from the microbiologic laboratory. Positive yield and incremental yield of each sputum specimen were calculated.
  
  
  RESULTS
  There were 401 patients during the study period, 153 (38.2%) had positive smear for acid-fast bacilli. Overall diagnostic yields of solid culture media and liquid culture media, were 72.1% and 95.3% respectively. Incremental of overall diagnostic yield from 1 to 2 and 2 to 3 sputum specimens were 8% and 6% respectively.
  
  
  CONCLUSIONS
  In place where a routinely combined smear and culture for every sputum sample submitted to the microbiologic laboratory, two specimens are sufficient for the diagnosis in nearly all pulmonary tuberculosis patients.
authors.affiliation: Division of Respiratory Disease and Tuberculosis, Department of Medicine, Faculty of Medicine, Siriraj Hospital, Bangkok, Thailand. siade@mahidol.ac.th
authors.forename: Nitipatana
authors.initials: N
authors.lastname: Chierakul
authors.forename: Pichaya
authors.initials: P
authors.lastname: Petborom
authors.forename: Suporn
authors.initials: S
authors.lastname: Foongladda
authors.forename: Suthipol
authors.initials: S
authors.lastname: Udompunturak
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D012189:Retrospective Studies; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis*