Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2002
Publication Date: 1/1/2003
Citation: Higgins, J.A., Cooper, M., Tucker, L., Black, S., Miller, D., Karns, J.S., Manthey, E., Breeze, R., Perdue, M.L. 2003. A field investigation of Bacillus anthracis contamination of U.S. Department of Agriculture and other Washington, D.C., buildings during the anthrax attack of October 2001. Applied and Environmental Microbiology. 69:593-599. Interpretive Summary: As a result of concerns for employee health and safety resulting from the anthrax bioterrorism outbreak in the metropolitan Washington, DC area in October, 2001, the USDA administration established a mobile laboratory in a warehouse in the Navy Yard on October 24, 2001. The laboratory was equipped with biosafety hoods to allow for direct examination of suspicious envelopes received at USDA, and other government agency mailrooms. Additionally, teams were dispatched to 30 locations in the metro area to obtain swab samples and air samples from mailrooms, with each location being sampled once every three days. Back at the mobile laboratory, DNA was extracted from the swab and air samples and analyzed by PCR for the presence of Bacillus anthracis. The swab and air samples were also analyzed by culture and microscopy at the National Veterinary Services Laboratory in Ames, IA. As of February, 2002, 4 locations: the Economic Research Service, Forest Service, USDA South Building, and Office of Personnel Management mailrooms, were found to have viable anthrax spores on the premises. However, no employees have reported infections with this agent.
Technical Abstract: In response to an outbreak of bioterrorism in the Washington, DC area in October 2001 a mobile laboratory (ML) was set up in the city to conduct rapid molecular tests for the detection of Bacillus anthracis spores. The ML contained two Class I laminar flow hoods, a small autoclave, and two ruggedized advanced pathogen identification devices (RAPID). Envelopes, and swab and air samples collected from 30 locations in the metropolitan area once every three days, were subjected to examination and DNA extraction, followed by real time PCR using freeze dried, fluorescent probe-based reagents. Attempts to culture B. anthracis from swab and air samples were also made, both in the ML and at the National Veterinary Service Laboratory in Ames, IA. To date, 136 real time PCR runs (comprising 1543 samples, with a failure rate of under 0.05%) and over 1700 platings, have been conducted. While none of the PCR assays on DNA extracted from swab and air samples were positive, viable spores were cultured from four locations, in the metropolitan area, in October, November, and December, 2001. DNA extracted from these suspected B. anthracis colonies was positive by real time and conventional PCRs for the lethal factor, pXO1, capA, and vrr genes; sequence analysis of the latter amplicons indicated high homology with a variety of B. anthracis strains.