Evaluating Composite Sampling Methods of Bacillus Spores at Low Concentrations

Area of Science:

• Environmental science
• Analytical chemistry
• Microbiology

Background:

• The 2001 Amerithrax attacks revealed lengthy remediation times, particularly for environmental sampling and analysis.
• Composite sampling offers a solution to reduce response times by enabling combined sample analysis.

Purpose of the Study:

• To evaluate the effectiveness of three composite sampling methods for Bacillus atrophaeus spore detection.
• To compare recovery efficiency across different surface types and contamination levels.

Main Methods:

• Tested single medium single pass composite (SM-SPC), single medium multi-pass composite (SM-MPC), and multi-medium post-sample composite (MM-MPC) methods.
• Utilized Bacillus atrophaeus spores at concentrations from 5 to 100 CFU/coupon on clean and dirty surfaces.
• Analyzed recovery efficiency on stainless steel, vinyl tile, ceramic tile, and painted drywall.

Main Results:

• Multi-medium post-sample composite (MM-MPC) demonstrated higher overall recovery efficiency compared to SM-SPC and SM-MPC.
• Recovery efficiency varied by surface material, with vinyl tile showing lower efficiency for composite methods.
• MM-MPC proved effective for clean and dirty surfaces, suggesting its utility in contamination response.

Conclusions:

• Post-sample compositing, specifically MM-MPC, is a viable strategy to decrease sample analysis time during Bacillus anthracis contamination events.
• This method can be applied to both clean and dirty surfaces, enhancing response efficiency.