Simple and rapid method for detection of bacterial spores in powder useful for first responders

The need for a rapid method by which first responders can screen for the presence of spores in powder samples has been increased since the anthrax attack of 2001. The majority of powders that were sampled in the context of that attack were hoaxes and did not contain Bacillus anthracis. The large number of samples overwhelmed the analysis capacity of public health laboratories. A rapid screening method for determining the presence of viable spores would eliminate much laboratory work and expedite procedures for identification if spores were detected. In the study reported here, Bacillus thuringiensis was used as a surrogate for B. anthracis to investigate if heat shock followed by luminescence analysis would allow rapid quantification of viable spores. The aim of the study was to investigate the best and fastest heat shock conditions that would trigger the breakdown of endospore dormancy of Bacillus species and give a higher luminescence signal. Heat shock and luminescence do not identify the type of spores in a powder sample, but they can detect the presence of viable spores in near real time. Different types of germinant were tested at different conditions (germination duration, temperature, concentration). The rapid method was compared with the traditional plate count method. The results showed that the rapid method can be used as a rapid (< 15 min), sensitive (< 100 spores), and inexpensive detection technique. The rapid method can be applied on site when suspicious powder is found and enables decision making for further identification.