Yield of smear, culture and amplification tests from repeated sputum induction for the diagnosis of pulmonary tuberculosis

Int J Tuberc Lung Dis. 2001 Sep;5(9):855-60.


Objectives: To assess the yield of repeated sputum induction for the diagnosis of active tuberculosis in patients who do not produce spontaneous sputum, or with smear-negative spontaneous samples.

Methods: Induced sputum was examined with fluorescent microscopy, two amplification methods (PCR Amplicor MTB, and MTD2), and cultured for mycobacteria using liquid (Bactec 12B) and Lowenstein-Jensen media. Bronchoscopy and collection of other specimens were performed at the discretion of the treating physician.

Results: A total of 1115 sputum inductions performed in 500 patients without adverse events yielded an adequate specimen in 1113 (99.8%), and microbiological confirmation in 43 of 44 (98%) culture-positive active TB cases. Yield increased with repeated sputum induction. The cumulative yield for acid-fast bacilli smear and mycobacterial culture was 64% and 70% respectively for one, 81% and 91% for two, 91% and 99% for three, and 98% and 100% for four induced samples. Yield of PCR also increased with the greater number of induced samples tested.

Conclusions: Repeated sputum induction could considerably improve diagnostic accuracy for pulmonary TB.

Publication types

  • Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analysis of Variance
  • Bronchoscopy
  • Humans
  • Microscopy, Fluorescence
  • Mycobacterium tuberculosis / genetics*
  • Mycobacterium tuberculosis / isolation & purification*
  • Nucleic Acid Amplification Techniques*
  • Prospective Studies
  • Saline Solution, Hypertonic / administration & dosage
  • Sensitivity and Specificity
  • Specimen Handling
  • Sputum / microbiology*
  • Tuberculin Test
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / genetics*


  • Saline Solution, Hypertonic