Microscopic detection of Mycobacterium tuberculosis in direct or processed sputum smears

Rev Soc Bras Med Trop. 2018 Mar-Apr;51(2):237-239. doi: 10.1590/0037-8682-0238-2017.

Abstract

Introduction: Microscopic identification of active pulmonary tuberculosis (PTB) from direct smears of sputum (DS) is widely used for detection, but has limited sensitivity. Here, we assessed the yield of acid-fast bacilli (AFB) detection in processed sputum smears (PSS).

Methods: Sputum samples were simultaneously analyzed by direct sputum smearing and after chemical treatment and spontaneous sedimentation.

Results: Of the 1,719 samples analyzed, 16.4% were positive for AFB in conventional DS and 21.4% in PSS, corresponding to a 30% increase in detection.

Conclusions: Increased sensitivity from analyzing PSS and better safety protocols will contribute to improved detection and control of the disease.

MeSH terms

  • Humans
  • Mycobacterium tuberculosis / isolation & purification*
  • Sensitivity and Specificity
  • Specimen Handling / methods*
  • Sputum / microbiology*
  • Tuberculosis, Pulmonary / diagnosis*