Table 2

Plate count method	Log₁₀ Inoculum	Mean spores inoculated/surface (sd)	Mean CFU recovered (sd)	%R (sd)	Precision^a %CV_w	Reproducibility^b %CV^b	%CV_tot^c	Sensitivity^d (%)	n sponge-wipes
Sampled wipes (Sampling + processing)	1	26.1 (13.6)	9.1 (6.1)	34.6 (23.0)	66.0	13.8	67.4	93.0	63
	2	536 (134.1)	132.6 (63.0)	24.4(11.2)	35.0	31.3	47.0	100	63
	4	33,140 (6,743)	9,984.0 (2,707)	30.1 (8.2)	19.9	19.9	27.9	100	54
		overall		29.7 (16.4)	51.8	13.6	55.9	97.7	189

	Log₁₀ Inoc-ulum	Spores inoculated/wipe	Mean CFU Recovered (sd)	% R (sd)	Precision ^a %CV _w	Reproducibility^b %CV^b	%CV_tot^c	Sensitivity^d (%)	Specificity^e (%)	n pos ctrls	n neg ctrls
Control wipes (processing only)	1	8.7 (3.9)	5.0 (5.6)	46.3 (33.0)	54.0	26.9	72.0	82.4	100	17	18
	2	178.7 (44.7)	112.7 (42.7)	66.5 (23.3)	20.3	20.3	35.8	100	100	18	18
	4	11,047 (2247.8)	6726.1(3809.8)	77.9 (13.6)	10.6	10.6	17.8	100	94.4^f	18	18
		overall		65.9 (24.1)	39.0	NA^f	45.4	94.1	98.1	53	54

^aVariance within laboratories
^bVariance between laboratories.
^cTotal variance for each inoculum level incorporates within lab and between lab variability Overall total variance also incorporates between inoculum level, in addition to
within and between lab variability.
^dPercent of true positive sponge-wipes
^ePercent of true negative control sponge-wipes
^fCross contamination of one negative control plate due to malfunctioning biosafety cabinet was responsible for the specificity being less than 100%.

Table 2: Spore Recovery from a 10” x 10” (645 cm²) steel surface using a sponge-wipe sampling and processing protocol.