Reliable detection of Bacillus anthracis, Francisella tularensis and Yersinia pestis by using multiplex qPCR including internal controls for nucleic acid extraction and amplification

Table 2 Precision and detection limits of the multiplex PCRs

organism	Target	Efficiency (%)	Repeatability (SD of C_q)^a	LOD target amplicons (copies/reaction)^b	LOD gDNA (fg/reaction)^b
B. anthracis	sspE	94.5	0.045	2.6 (1.6-7.5)	22.6 (9.9-148.5)
	cya	94.7	0.057	6.5 (3.7-19.6)	50.5 (19.1-408.3)
	capB	94.8	0.051	3.6 (2.0-10.7)	15.7 (9.9-78.9)
F. tularensis	fopA	98.2	0.042	7.2 (3.5-24.7)	11.8 (5.5-66.4)
	ISFtu2	98.1	0.075	4.1 (2.2-12.8)	0.6 (0.2-3.4)
	pdpD	95.9	0.067	6.1 (3.1-20)	4.2 (2.5-25.6)
Y. pestis	ypo0393	93.1	0.057	1.7 (1.2-3.5)	116 (59.3-967.2)
	caf1	93.2	0.099	1.9 (1.3-4.1)	43.2 (23.9-277.2)
	pla	93.1	0.047	3.6 (2.2-8.9)	29.6 (13.5-191.9)
B. thuringiensis	cry1	94.6/95/92.9^c	0.047/0.055/0.057 ^c	ND	ND

^a Values represent the average from the standard deviations calculated at 5 different dilutions from 4 replicate Cqs measurements.
^b Values displayed represent the lowest DNA concentration at which 95% of the positive samples are detected, as calculated by using probit analysis. Shown between brackets are the 95% confidence limits of the calculated LODs.
^c B. thuringiensis internal control added to B. anthracis, F. tularensis and Y. pestis, respectively
ND = not determined

ISSN: 1471-2180