Optimizing tuberculosis testing for basic laboratories

Am J Trop Med Hyg. 2010 Oct;83(4):896-901. doi: 10.4269/ajtmh.2010.09-0566.


Optimal tuberculosis testing usually involves sputum centrifugation followed by broth culture. However, centrifuges are biohazardous and scarce in the resource-limited settings where most tuberculosis occurs. To optimize tuberculosis testing for these settings, centrifugation of 111 decontaminated sputum samples was compared with syringe-aspiration through polycarbonate membrane-filters that were then cultured in broth. To reduce the workload of repeated microscopic screening of broth cultures for tuberculosis growth, the colorimetric redox indicator 2,3-diphenyl-5-(2-thienyl) tetrazolium chloride was added to the broth, which enabled naked-eye detection of culture positivity. This combination of filtration and colorimetric growth-detection gave similar results to sputum centrifugation followed by culture microscopy regarding mean colony counts (43 versus 48; P = 0.6), contamination rates (0.9% versus 1.8%; P = 0.3), and sensitivity (94% versus 95%; P = 0.7), suggesting equivalency of the two methods. By obviating centrifugation and repeated microscopic screening of cultures, this approach may constitute a more appropriate technology for rapid and sensitive tuberculosis diagnosis in basic laboratories.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antitubercular Agents / pharmacology
  • Bacteriological Techniques / methods*
  • Bacteriological Techniques / standards*
  • Colorimetry
  • Drug Resistance, Multiple, Bacterial
  • Female
  • Filtration
  • Humans
  • Laboratories / standards*
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / isolation & purification*
  • Sensitivity and Specificity
  • Sputum / microbiology
  • Tuberculosis / diagnosis*
  • Tuberculosis / drug therapy
  • Tuberculosis / microbiology
  • Workforce
  • Workload
  • Young Adult


  • Antitubercular Agents