Development of three real-time PCR assays to detect Bacillus anthracis and assessment of diagnostic utility.

Three real-time PCR assays to detect Bacillus anthracis genetic targets (pXO1; pXO2 and chromosome) were developed. Two of the PCR assays (pXO1-MGB and Ba chr-MGB) were tested against DNA extracts produced from whole blood samples obtained from a replicated B. anthracis murine infection model. Across all three models 45 samples were tested in total, within which a subset of 41 samples were shown to contain B. anthracis by either PCR or microbiological culture. Using microbiological culture as an analogue of conventional blood culture (as used in clinical settings) the detection rates of PCR and blood culture were compared. In two of the murine models blood culture had a significantly higher detection rate than PCR (BA1, p=0.004; BA3, p=0.013). In the BA2 model there was no significant difference between the detection rates of PCR and blood culture.