Evaluation of spore extraction and purification methods for selective recovery of viable Bacillus anthracis spores.

To investigate methods of improving anthrax spore detection with PLET. Comparisons were made of PLET and blood-supplemented PLET to recover and distinguish spores of a variety of Bacillus species. Heat and ethanol purification of spores, and spore extraction from soil with water and high specific gravity sucrose plus non-ionic detergent, were also carried out. PLET was more selective and suitable than blood-supplemented PLET for detection of anthrax spores in the environmental specimens. However, PLET is not an optimal spore recovery medium. Purification of spores with ethanol was as effective as heat purification. High specific gravity sucrose plus detergent extraction solutions may be more sensitive than extraction with water. This study highlights shortcomings with the standard PLET isolation of anthrax spores and describes ways in which the procedure may be improved.