Tb investigation and lab testing diagnosis and process all over the world.pptx

Tb investigation and lab testing process

1. Investigation & lab diagnosis of TB

2. SPECIMEN COLLECTION ADULT • Pulmonary TB - Rinse mouth with water - Deep Coughing - 2 sputum specimens spot and early morning - in wide mouth sterile container • Ideal sputum sample should have Pus Cells > 25 and Epithelial Cells < 25 • If previous is not available - Laryngeal Aspirate or Bronchial washings - Collected CHILDREN • Gastric Aspirate Sputum sample is obtained by coughing and is examined in the laboratory

3. DIGESTION, DECONTAMINATION, CONCENTRATION OF SPECIMEN Two Methods • Petroff's method (Commonly Used) • NALC + 2% NaOH

4. DIRECT MICROSCOPY • Ziehl - Neelsen Technique - Long slender, beaded, uniformly stained acid fast bacill i • Kinyoun's cold acid fast staining • Auramine Phenol technique • Acid Alcohol (3% HCI + 95% Ethanol) used to differentiate between MTB and saprophytic mycobacterium

5. CULTURE METHODS Solid medium - LJ medium (takes 6 to 8 weeks) Automated systems - - shows rough, tough and buff colonies. Automated systems - BACTEC MGIT, BacT- ALERT(takes 2 to 3 weeks) Liquid medium - middle brook 7H9 medium

6. BIOCHEMICAL IDENTIFICATION The following tests differentiate MTB from M.bovis • Niacin test +ve • Nitrate reduction test +ve • Pyranzinamidase test +ve • Resistant to TCH these test differentiate MTB from ATB • Aryl sulfatase test • Catalase-peroxidase test

7. MOLECULAR METHODS • PCR & LCR done • GeneXpert/CB-NAAT (Cartridge based nucleic acid amplification test) . Highly sensitive TB test, high accuracy compared to smear microscopy zero cost to patient, detect resistance to rifampicin drug. • Molecular typing: IS6110 RFLP typing Spoligotyping

8. DIAGNOSIS OF LATENT TB • Tuberculin test • Antigen - PPD • Dosage -.1 ml (5TU) Site - ID in flexor aspect of forearm • Reading - looked for induration after 48 to 72 hrs. >= 10 mm positive 6-9 mm equivocal < 5 mm negative False positive: BCG & ATB False negative: Early and miliary TB

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