Modified rapid radiometric method for detection of Mycobacterium tuberculosis from sputum samples

Area of Science:

• Microbiology
• Medical Diagnostics
• Radiochemistry

Background:

• Early and accurate detection of Mycobacterium tuberculosis (M. tuberculosis) is crucial for effective tuberculosis (TB) management and control.
• Conventional diagnostic methods for TB can be time-consuming, delaying timely treatment initiation.
• Radiometric methods offer potential for faster microbial detection through metabolic activity monitoring.

Purpose of the Study:

• To develop and evaluate a modified, simple radiometric method for the early detection of M. tuberculosis in sputum samples.
• To compare the diagnostic performance and speed of the radiometric method against visual inspection methods.
• To assess the mean detection time and replication time of M. tuberculosis using the developed radiometric assay.

Main Methods:

• Development of a biphasic vial system for radiometric detection of 14C-CO2.
• Utilized 14C-U-acetate as a substrate on glycerol-free Lowenstein-Jensen medium (LJM).
• Tested 84 smear-positive sputum samples, comparing radiometric results with visual methods.

Main Results:

• The radiometric method achieved detection rates of 53.3% (week 1), 60.7% (week 2), and 82.1% (week 3).
• Visual methods showed significantly lower detection rates: 1.2% (week 1), 11.9% (week 2), and 54.8% (week 3).
• Mean detection time was substantially shorter with the radiometric method (10.7 days) compared to the visual method (21.0 days).

Conclusions:

• The modified radiometric method provides a simple and effective approach for early M. tuberculosis detection in sputum.
• This radiometric assay significantly reduces the mean detection time, facilitating quicker diagnosis and treatment.
• The method demonstrates high sensitivity and improved detection rates, especially in the early stages of culture.