The Assessment of Viability of M. Tuberculosis after Exposure to CPC Using Different Methods

Area of Science:

• Microbiology
• Mycobacteriology
• Cell Biology

Background:

• Mycobacterium tuberculosis (M. tuberculosis) is a significant human pathogen.
• Effective preservation methods for M. tuberculosis are crucial for research and diagnostics.
• Cetylpyridinium chloride (CPC) is a potential agent for preserving biological samples.

Purpose of the Study:

• To evaluate the metabolic activity and viability of M. tuberculosis after storage with CPC.
• To assess the impact of CPC on mycolic acid synthesis in M. tuberculosis.
• To investigate potential cell wall damage in M. tuberculosis due to CPC exposure.

Main Methods:

• Utilized FDA-EB vital staining to assess metabolic activity of M. tuberculosis.
• Performed viable counts on LJ medium to determine cell viability.
• Employed High-Performance Liquid Chromatography (HPLC) to quantify mycolic acid content.
• Tested both clinical isolates and the standard M. tuberculosis H37Rv strain.

Main Results:

• FDA-EB staining indicated a shift from metabolically active (green) to inactive (red-orange) cells after CPC treatment.
• Viable counts after CPC storage were comparable to 0-day controls, showing maintained viability.
• HPLC analysis revealed reduced mycolic acid synthesis in M. tuberculosis exposed to CPC.
• CPC treatment for 7 days led to a reduction in mycolic acid content.

Conclusions:

• CPC renders M. tuberculosis cells metabolically inactive during storage but allows growth upon removal.
• Viability of M. tuberculosis is largely maintained in CPC with minimal reduction.
• Reduced mycolic acid content suggests potential damage to the M. tuberculosis cell wall.
• CPC storage appears to preserve M. tuberculosis viability while impacting metabolic functions and cell wall integrity.