1. Module – 2
LABORATORY DIAGNOSIS OF
TB AND QUALITY ASSURANCE
BY
Batch II
Dr Anchlesh Tekam
Facilitator - Dr Neeta Singla

2. Symptoms of tuberculosis
A Smear positive pulmonary tuberculosis (PTB) has potential to spread
infection to 10 – 15 persons annually.
Pulmonary TB suspects
A pulmonary TB suspect is defined as:
• An individual having cough of 2 weeks or more.
• Contacts of smear positive TB patients having cough of any duration
• Suspected/confirmed extra-pulmonary TB having cough of any duration
• HIV positive patient having cough of any duration

3. Tools for diagnosis of Pulmonary TB in adults:
• Sputum smear microscopy
• Chest X-ray
• Sputum culture and DST for diagnosis of Drug Resistant TB
• Newer rapid diagnostic tools for detection of MDR TB
Non-commercial solid culture
Non-commercial liquid culture methods
Liquid culture - (MGIT)
Molecular Assays – PCR based, The most widely
evaluated and used assays are Line Probe Assays (LPA)
GeneXpert

4. Diagnostic Algorithm For Pulmonary TB
Cough For 2 Weeks or More
2 Sputum Smears
1 or 2 Positive 2 Negative
Antibiotics 10-14 days
Cough Persists
Sputum Smear-positive TB
(Anti-TB Treatment)
Repeat 2 Sputum
Examination
Negative 1 or 2 Positive
Sputum Positive TB (Anti-TB
Treatment)
Continued on Next Slide

5. Diagnostic Algorithm For Pulmonary TB
Repeat 2 Sputum
Examination
Negative
Continued
X-Ray
Negative for TB Suggestive of TB
Sputum Smear-negative TB
(Anti-TB Treatment)
Non
TB

7. Grading
Examination Result Grading Minimum
No. of OIF
to be
examined
> 10 AFB/OIF Pos 3+ 20
1-10 AFB/OIF Pos 2+ 50
10-99 AFB/100 OIF Pos 1+ 100
1-9 AFB/100 OIF Pos SC (Actual No.) 100
No AFB/100 OIF Neg - 100

9. Quality Assurance (QA) for smear microscopy
Quality assurance system includes
Internal Quality Control (IQC)
• It’s a systematic internal monitoring of working practices.
• It includes technical procedures, checking instruments, quality of new
batches of staining solution, smear preparation, grading, equipment infection
control measures, waste management etc.
External Quality Assessment(EQA)
On site Evaluation
Panel Testing
RBRC
Quality Improvement(QI) - A process by which all components of smear
microscopy diagnostic services are carefully analyzed with the aim of looking
for ways to permanently remove obstacles to success.