A comprehensive comparison of Ziehl-Neelsen and fluorescence microscopy for the diagnosis of tuberculosis in a resource-poor urban setting

Int J Tuberc Lung Dis. 2003 Dec;7(12):1163-71.


Setting: Nairobi City Council Chest Clinic, Kenya.

Objectives: To establish the efficiency, costs and cost-effectiveness of six diagnostic strategies using Ziehl-Neelsen (ZN) and fluorescence microscopy (FM).

Design: A cross-sectional study of 1398 TB suspects attending a specialised chest clinic in Nairobi subjected to three sputum examinations by ZN and FM. Lowenstein-Jensen culture was used as the gold standard. Cost analysis included health service and patient costs.

Results: Of 1398 suspects enrolled, 993 (71%) had a complete diagnostic work-up involving three sputum specimens for ZN and FM, culture and chest X-ray (CXR). Irrespective of whether ZN or FM was used on one, two or three smears, the overall diagnostic process detected 92% culture-positive cases. Different strategies affected the ratio of smear-positive to smear-negative TB; however, FM was more sensitive than ZN (P < 0.001). FM performance was not affected by the patient's HIV status. The cost per correctly diagnosed smear-positive case, including savings, was 40.30 US dollars for FM on two specimens compared to 57.70 US dollars for ZN on three specimens.

Conclusion: The FM method used on one or two specimens is more cost-effective and shortens the diagnostic process. Consequently, more patients can be put on a regimen for smear-positive TB, contributing to improved treatment and reducing transmission.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Bacteriological Techniques / economics*
  • Bacteriological Techniques / methods
  • Confidence Intervals
  • Cost-Benefit Analysis
  • Cross-Sectional Studies
  • Developing Countries
  • Female
  • Health Resources
  • Humans
  • Kenya
  • Logistic Models
  • Male
  • Microscopy, Fluorescence
  • Middle Aged
  • Mycobacterium tuberculosis / isolation & purification*
  • Poverty
  • Probability
  • Reagent Kits, Diagnostic / economics
  • Sensitivity and Specificity
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / economics*
  • Urban Population


  • Reagent Kits, Diagnostic