This document discusses the diagnosis of tuberculosis. It outlines several microbiology tests for diagnosing TB, including sputum smear microscopy, mycobacterial culture techniques like BACTEC MGIT, and PCR-based tests like GeneXpert. Sputum smear microscopy has a sensitivity of 60% and results in 2 days, while mycobacterial culture has higher sensitivity but results take 2-6 weeks. GeneXpert is a WHO-endorsed PCR test that provides results in 90 minutes and also detects rifampin resistance. The document recommends sputum tests over blood tests for diagnosing TB in adults and states that tuberculin skin tests have no role in adult diagnosis.

1. Diagnosis of Tuberculosis
Current concepts
Dr A D Deshpande
MD (Micro) , MD (Patho)

2. WHO
Int. Std. of TB Care
Std. of TB Care in
India
RNTCP

3. India (25%)

5. India = 1500 deaths / day
because of Tuberculosis

6. DiagnosisDisease
 60 days 
15 New cases

7. Robert Koch

8. My name is Koch

9. World TB day 24 March
March 24 1882 --
Dr Robert Koch discovered TB bacillus

10. Lab Diagnosis of
Tuberculosis

11. Microbiology Tests
 Sputum for ZN stain
 Culture
 PCR based Tests

12. Sputum for ZN stain
2 Samples
( Sensitivity)
• LED microscope
• Fluorescent
microscope

13. Sputum for ZN stain

14. Culture
L J Medium BACTEC MGIT

15. Culture - BACTEC MGIT
Results : 15 days 42 days
Most Sensitive Test
Antibiotic Sensitivity for full 13 drugs
Sample to be sent in Saline

16. • LINE PROBE ASSAY PCR REC BY RNTCP
• OTHER PCR TESTS DONE BY LABS LIKE RANBAXY
AND METROPOLICE
( ALL THESE METHOD NOT VALIDATED BY WHO )
PCR Based Tests

17. PCR based Tests
Gene Xpert
- Fast (90 mins)
- Easy to perform
- Genotypic Drug
Resistance (Rif)
- Dead Bacteria can
give Test positive
WHO endorsed Test, 2010

18. Extra pulmonary TB
Lymphnode – Pus
CSF
Synovial fluid
Endometrial tissue
Pleural fluid
Any Pus
•BACTEC MGIT Culture
& Sensitivity
• Gene Xpert
First do smear for ZN stain

19. Cost - Subsidized Rates ~ IPAQT
(Initiative for promoting Affordable & Quality tests)
• Gene Xpert : 2000 Rs
• Line probe Assay (for Sputum Positive samples
Only Via RNTCP) : 1600 Rs
• BACTEC MGIT Culture : 900 Rs

21. Serum IgG , IgM for TB
by Govt. of India

22. 7 June 2012

26. Don’t send
patients Blood to
Diagnose TB

27. • Not recommended in Adults by RNTCP
• Useful in Children
Tuberculin Test (Mantoux Test)

28. Tuberculin Test in Vitro = TB Gold
Same are IGRA & Quantiferon
tests
NOT RECOMMENDED IN ADULTS
NOT

29. Latent TB
• Child contacts
• All Immunosuppressed – HIV Patients
• In US

30. Diagnosis of Tuberculosis in Pathology
FNAC Histopathology

31.  >15 Days Productive cough / Doubtful
Radiological finding - Sputum for ZN stain
 Culture (BACTEC MGIT) - Most Sensitive
 Gene Xpert – Fast
 No role of Tuberculin Test in Adults
 Blood is not a sample, Serology is Banned

32. Thank you