This ppt includes all the investigations for the diagnosis of pulmonary and extrapulmonary tuberculosis. This will be a great help in your university exams as well as competitive exams. All the best.

1. TUBERCULOSIS
SHREYA SAGARAD
MBBS-II
Moderators
Dr Kajal Chetty
Dr Madhavi Kulkarni

2. • Diagnosis
• Investigations

3. Diagnosis
•Frequently clinical diagnosis
•Any person with cough >2weeks, fever >2weeks,
significant weight loss, haemoptysis, etc and any
abnormality in chest radiograph must be evaluated
for TB
•Children with persistent fever, cough >2weeks,
loss of weight / no weight gain, contact with pul
TB cases must be evaluatedfor TB

4. •PLHIV(people living with HIV), malnourished, diabetes,
cancer, on immunosupressants, steroid therapy-
should be regularly screened
•High risk groups- health care workers, prisoners,
slum dwellers, occupational groups such as miners

5. •Confirmed diagnosis requires identification of M.
Tuberculosis- investigations
microscopies,cultures, biopsiesandaspirations
•lungs: x3 morning sputums for microscopy and
culture
•Biopsies/aspirations of extrapulmonarysites
for microscopies and culture

6. •Culture
On solid agar-growth in 3-6 weeks
In liquid media- within 2 weeks
PCR- within hours
•Microscopy-look for acid fast bacilli (AFBs)
→mycobacterial infection
•60-70% pulmonary TB- sputum positive for
Mycobacterium
•Extrapul TB
•Positive cultures are not so high for lymph node
disease, pleural TB and meningitis
•Yield from culture are much lower

7. Investigations
Screening tests
1. Tuberculin skin test
2. Interferon gamma release assay
Confirmatory tests
1. Smears and cultures
2. Automated culture methods
3. Serological tests
4. Molecular methods
Others:
CBC, ESR/CRP, LFT, RFT, DST

8. •Tuberculinskin test:latent
tuberculosis
Intracutaneousinjection of
purified protein derivative of
M. Tuberculosis
Induces a visible and palpable
induration that peaks in 48 to
72 h

10. •IGRA (interferongamma release assay)
-In vitro tests
-Lymphocytes from the patients are stimulated with
protein antigens from M. Tuberculosis
-Production of INF-ɣ by T-cells is measured
Note: false negative- viral inf, sarcoidosis,
malnutrition,Hodgkin lymphoma, immunosuppression
and active tuberculous disease
False positive tst-inf by atypical mycobacteriaor prior
vaccinationwith BCG

11. IGRA

12. Confirmatory Tests:
Specimens to be collected:
• In pul TB: sputum sample
• In extrapulmonary TB:

13. CSF Pleural fluid collection

15. Gastric Lavage

16. •Sputum test- active tuberculosis
•Acid fast smears-
• ZN staining
• Kinyoun’s cold acid fast staining
• Flourescent (auramine) stain: more
sensitive and rapid
•Cultures: Löwenstein-Jensen medium
•Chest X-ray and CT scan

17. Ziehl-Neelsen– long, slender,beaded,
less uniformly stainedred coloured AFB
Bacilliseen in auramine
staining

18. LJ medium
(rough, tough and buff
coloured colonies -> 6-8
weeks)

19. •Automated culture methods: BACTEC MGIT,
BacT/ALERT systems

20. •GeneXpert/CB-NAAT(cartridge-based nucleic acid
amplification test): children and PLHIV
•Truenat/Chip-based NAAT
•Serological tests- banned

21. Gene Xpert
• MTB Complex
• Rifampicin resistance(rpoB Gene mutations)
• WHO- initial testfor diagnosisof EPTB (CSF, lymph nodes and other
tissue specimens)
• Overall sensitivityof 85% reaching 98%[AFB +], 70%[AFB -]
• Rifampicin resistance
• Sensitivity:96%
• Specificity:98%
Newer Xpert MTB/RIF Ultra
• Sensitivity 90% incl trace cells
• +12% - HIV infectedpersons
• +17% - smear(-) culture (+)

22. • Drug Susceptibility Testing (DST):
o After culturing
o Antibiotic→ sensitivity or
resistance
o Rule out drug resistant TB
o Choosing right treatment

23. •Extra-pulTB
•Drug sensitivity test(DST), CB-NAAT, molecular
tests, histo-pathological examination