Evaluation and Validation of a Real-Time Polymerase Chain Reaction Assay for Rapid Identification ofBacillus anthracis

To the Editor: During the 2001 anthrax outbreak, we evaluated and validated a highly sensitive and specific three-target (two plasmid and one chromosomally located target) 5´ nuclease assay (real-time polymerase chain reaction [PCR]) for detection and identification of Bacillus anthracis. This PCR assay was successfully used to rapidly test hundreds of suspect isolates as well as screen environmental samples for the presence of B. anthracis throughout the 2001 anthrax outbreak. For the first time in an outbreak setting, a PCR assay was used to detect B. anthracis directly from clinical specimens, consequently becoming a part of the laboratory confirmation of anthrax. In this letter, we describe the evaluation of this assay on a diverse panel of bacterial isolates including isolates obtained throughout the outbreak. A supplement, which includes data on the use of this assay on environmental and clinical specimens, is online (available from http://www.cdc.gov/ncidod/EID/vol8no10/02-0393sup.htm).