Rapid Detection of Bacillus anthracisBloodstream Infections by Use of a Novel Assay in the GeneXpert System

ABSTRACTBacillus anthracisis a tier 1 select agent with the potential to quickly cause severe disease. Rapid identification of this pathogen may accelerate treatment and reduce mortality in the event of a bioterrorism attack. We developed a rapid and sensitive assay to detect B. anthracisbacteremia using a system that is suitable for point-of-care testing. A filter-based cartridge that included both sample processing and PCR amplification functions was loaded with all reagents needed for sample processing and multiplex nested PCR. The assay limit of detection (LOD) and dynamic range were determined by spiking B. anthracisDNA into individual PCR mixtures and B. anthracisCFU into human blood. One-milliliter blood samples were added to the filter-based detection cartridge and tested for B. anthracison a GeneXpert instrument. Assay specificity was determined by testing blood spiked with non-anthrax bacterial isolates or by testing blood samples drawn from patients with concurrent non-B. anthracisbacteremia or nonbacteremic controls. The assay LODs were 5 genome equivalents per reaction and 10 CFU/ml blood for both the B. anthracisSterne and V1B strains. There was a 6-log10dynamic range. Assay specificity was 100% for tests of non-B. anthracisbacterial isolates and patient blood samples. Assay time was less than 90 min. This automated system suitable for point-of-care detection rapidly identifies B. anthracisdirectly from blood with high sensitivity. This assay might lead to early detection and more rapid therapy in the event of a bioterrorism attack.