[A study on the count of living BCG bacilli using BL and FS methods]

Area of Science:

• Microbiology and Immunology
• Vaccine Quality Control
• Biotechnology Applications

Context:

• Accurate enumeration of viable Bacillus Calmette-Guérin (BCG) bacilli is critical for ensuring vaccine efficacy and safety.
• The World Health Organization (WHO) currently recommends the colony-forming unit (CFU) method for BCG quality surveillance.
• Existing methods like CFU can be time-consuming and exhibit significant variability, impacting reliable quality assessment.

Purpose:

• To evaluate the efficacy of rapid bioluminescent (BL) and fluorescent staining (FS) techniques for BCG quality surveillance.
• To compare the precision and reliability of BL and FS methods against the standard CFU technique.
• To assess the correlation of BL and FS results with in vivo efficacy indicators, such as the Open Tuberculin (OT) test in newborns.

Summary:

• This study compared rapid bioluminescent (BL) and fluorescent staining (FS) methods with the traditional CFU technique for BCG quality assessment.
• The BL technique, measuring Adenosine Triphosphate (ATP), showed a strong significant correlation with CFU (r = 0.973, P < 0.005).
• The BL method exhibited a substantially lower coefficient of variation (2.72%) compared to the CFU method (39.5%), indicating superior precision. FS and BL results were also consistent with OT reactions in newborns.

Impact:

• The findings suggest that BL and FS techniques provide a more accurate, reproducible, and potentially faster alternative for BCG quality control.
• Adoption of these advanced methods could enhance global BCG vaccine surveillance, leading to improved vaccine quality and public health outcomes.
• This study supports the integration of rapid, sensitive detection methods into routine vaccine quality assurance protocols.