Detection of Mycobacterium tuberculosis in pediatric stool samples using TruTip technology

Area of Science:

• Pediatric infectious diseases
• Molecular diagnostics
• Microbiology

Background:

• Childhood tuberculosis (TB) diagnosis is hindered by the difficulty in obtaining sputum samples.
• Stool is a viable alternative specimen for molecular detection of Mycobacterium tuberculosis (Mtb).
• The TruTip workstation offers automated lysis and extraction for Mtb detection.

Purpose of the Study:

• To evaluate stool as an alternative specimen for Mtb detection in children.
• To assess the performance of the TruTip workstation for Mtb DNA extraction and real-time PCR.

Main Methods:

• Stool samples from 259 children (0-14 years) with TB symptoms in Lima, Peru were analyzed.
• Mtb DNA was detected using the TruTip workstation for extraction and IS6110 real-time PCR.
• Assay sensitivity and specificity were calculated for culture-confirmed, clinically-diagnosed unconfirmed, and TB-ruled-out groups.

Main Results:

• Assay sensitivity was 59% for culture-confirmed TB and 1.2% for clinically-diagnosed unconfirmed TB.
• Specificity was high at 97%.
• 100% sensitivity was observed in smear-positive TB cases; 40% in smear-negative, culture-confirmed TB cases. Older age, smear/culture positivity, sputum production, and cavitary disease were associated with positive stool results.

Conclusions:

• Stool testing using the TruTip workstation and IS6110 PCR shows comparable sensitivity and specificity to existing methods like Xpert.
• Further research should focus on resistance detection and improving sensitivity for low bacillary loads.