. 2021 Sep 23;2(6):409–414. doi: 10.3168/jdsc.2021-0144

Table 1.

Cycle threshold (Ct) values for Coxiella burnetii DNA detection after real-time PCR of dried milk spots on Whatman FTA Elute Micro Cards (FTA) after storage at room temperature (20–22°C) or 37°C for up to 29 d

Time	Master sample	Tested samples
		Undiluted		Dilution 10⁻¹		Dilution 10^minus;2		Dilution 10^minus;3		Dilution 10^minus;4		Dilution 10^minus;5
		20–22°C	37°C	20–22°C	37°C	20–22°C	37°C	20–22°C	37°C	20–22°C	37°C	20–22°C	37°C
Day 0	20.8
Day 1		26.0^a	22.8^b	27.2^a	27.3^b	30.7	30.3	33.1	33.1	38.7	ND²	ND	ND
Day 4		24.2^a	21.6^b	26.6^a	25.5^b	28.4	31.2	32.2^*	31.2^*	ND	39.1	ND	ND
Day 6		24.3^a	22.8^b	27.6^a	26.3^b	29.1	30.1	32.4	32.3	34.5	37.4	ND	38.2
Day 8		24.4^a	22.0^b	27.1^a	27.3^b	28.1	29.3	32.7	31.5	36.1	ND	ND	ND
Day 11		24.6^a	21.4^b	26.2^a	26.4^b	29.1	29.7	34.4^*	33.8^*	36.0	38.0	ND	ND
Day 15		25.2^a	21.4^b	27.3^a	25.4^b	29.3	29.8	33.0	32.7	ND	37.9	ND	ND
Day 20		25.2^a	22.4^b	27.2^a	24.5^b	29.6	29.8	31.7	32.7	ND	38.4	ND	ND
Day 29		23.4^a	23.1^b	26.8^a	26.2^b	30.5	30.1	33.5	32.2	34.4	36.8	ND	ND

Mean¹		24.7^a	22.2^b	27.0^a	26.1^b	29.4	30.0	32.9	32.4
SD¹		0.81	0.69	0.43	0.97	0.92	0.55	0.83	0.84
P-value (time)¹		0.635		0.517		0.408		0.046
P-value (temperature)¹		0.001		0.049		0.100		0.129

^a,b

For nondiluted and dilution 10⁻¹ samples: within each dilution, the values do not differ significantly with time (P > 0.05) but differ significantly with temperature (P < 0.05).

As Coxiella burnetii DNA was not detected at all times and temperatures, the mean, SD, P-value (time), and P-value (temperature) were not calculated.

Not detected.

Values on d 4 differed (P < 0.05) from those on d 11.