Emerging Infectious Diseases (Oct 2002)

Two-Component Direct Fluorescent-Antibody Assay for Rapid Identification of Bacillus anthracis

  • Barun K. De,
  • Sandra L. Bragg,
  • Gary N. Sanden,
  • Kathy E. Wilson,
  • Lois A. Diem,
  • Chung K. Marston,
  • Alex R. Hoffmaster,
  • Gwen A. Barnet,
  • Robbin S. Weyant,
  • Teresa G. Abshire,
  • John W. Ezzell,
  • Tanja Popovic

DOI
https://doi.org/10.3201/eid0810.020392
Journal volume & issue
Vol. 8, no. 10
pp. 1060 – 1065

Abstract

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A two-component direct fluorescent-antibody (DFA) assay, using fluorescein-labeled monoclonal antibodies specific to the Bacillus anthracis cell wall (CW-DFA) and capsule (CAP-DFA) antigens, was evaluated and validated for rapid identification of B. anthracis. We analyzed 230 B. anthracis isolates; 228 and 229 were positive by CW-DFA and CAP-DFA assays, respectively. We also tested 56 non–B. anthracis strains; 10 B. cereus and 2 B. thuringiensis were positive by the CW-DFA assay, and 1 B. megaterium strain was positive by CAP-DFA. Analysis of the combined DFA results identified 227 of 230 B. anthracis isolates; all 56 strains of the other Bacillus spp. were negative. Both DFA assays tested positive on 14 of 26 clinical specimens from the 2001 anthrax outbreak investigation. The two-component DFA assay is a sensitive, specific, and rapid confirmatory test for B. anthracis in cultures and may be useful directly on clinical specimens.

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