Non-continuous Percoll density gradient: a method for purifying Mycobacterium tuberculosis from dust.

backgroundMycobacterium tuberculosis (MTB) retains infectivity for 8-10 days in dry dust and survives up to 6-8 months in humid environments. Dust accumulated in ventilation systems and air-conditioning filters serves as a critical reservoir for MTB aerosol transmission, making its detection vital for environmental risk assessment in settings prone to clustered outbreaks, such as schools and hospitals. However, molecular detection of MTB in dust is hindered by inhibitors (e.g., humic acids and heavy metals), leading to high false-negative rates, while conventional decontamination methods (e.g., acid-base treatments) compromise bacterial viability and efficiency.

methodsThis study developed a non-destructive Percoll density gradient centrifugation method applied to both H37Rv-spiked artificial dust matrices and real-world air-conditioning dust samples from tuberculosis wards, enabling efficient isolation of viable MTB. This approach leverages buoyant density-based separation to minimize inhibitory effects and maintain bacterial viability.

results(1) For H37Rv-spiked artificial dust (10

conclusionThis method is operationally simple, non-toxic, and biocompatible, achieving high total recovery of MTB cells while maintaining a high proportion of viable among the recovered bacteria. It offers substantial potential for environmental monitoring and downstream sequencing analysis, aiding in environmental risk assessment and management of clustered tuberculosis outbreaks.