Table 2.

Microbial skin counts prior to and during preoperative skin antisepsis

Microbial skin counts/pathogensa	Timing			P-value for difference (paint 2 vs. 3)
	Prior to skin antisepsisb	After 2nd paint	After 3rd paint
Overall
$\sqrt{\mathrm{CFU}}\mathit{,}$ mean (SD)	11.2 (47.5)	0.5 (5.5)	0.1 (0.6)	0.2
CFU, median	7.0	0.0	0.0	0.002
CFU, IQR	1.0 to 79.8	0.0 to 0.0	0.0 to 0.0
CFU, range	0.0 to 50,000.0	0.0 to 7000.0	0.0 to 33.0
No. patients with 0 CFU (%)	30 (12.6)	203 (86.0)	224 (94.5)	0.003
No. patients with > 5 CFU (%)	126 (52.9)	5 (2.1)	3 (1.3)	0.9
No. patients with ≥1 pathogensc detected (%)	1 (0.4)	1 (0.4)	0 (0)	0.5
No. patients with insufficient microbial reductiona,d (%)	0 (0)	6 (2.5)	3 (1.3)	0.5
Povidone iodine subgroup
$\sqrt{\mathrm{CFU}}\mathit{,}$ mean (SD)	13.7 (60.2)	0.9 (7.0)	0.2 (0.72)	0.2
CFU, median	8.5	0.0	0.0	0.002
CFU, IQR	1.0 to 84.0	0.0 to 0.0	0.0 to 0.0
CFU, range	0.0 to 50,000.0	0.0 to 7000.0	0.0 to 33.0
No. patients with 0 CFU (%)	18 (12.5)	114 (80.2)	133 (93.0)	0.002
No. patients with > 5 CFU (%)	80 (55.2)	5 (3.5)	3 (2.1)	0.7
No. patients with ≥1 pathogensc detected (%)	1 (0.7)	1 (0.7)	0 (0)	0.7
No. patients with insufficient microbial reductiona,d (%)	0 (0)	6 (4.2)	3 (2.1)	0.5
Chlorhexidine subgroup
$\sqrt{\mathrm{CFU}}\mathit{,}$ mean (SD)	7.5 (12.4)	0.1 (0.3)	0.03 (0.2)	0.4
CFU, median	5.5	0.0	0.0	0.5
CFU, IQR	1.0 to 60.0	0.0 to 0.0	0.0 to 0.0
CFU, range	0.0 to 5000.0	0.0 to 2.0	0.0 to 1.0
No. patients with 0 CFU (%)	12 (12.8)	89 (95.0)	91 (97.0)	0.7
No. patients with > 5 CFU (%)	46 (48.9)	0 (0)	0 (0)	─
No. patients with ≥1 pathogensc detected (%)	0 (0)	0 (0)	0 (0)	─
No. patients with insufficient microbial reductiona,d (%)	0 (0)	0 (0)	0 (0)	─

Among the 239 individuals, CFU data were overall missing for 1 patient at baseline, for 3 patients after paint 2, and for 2 patients after paint 3

CFU colony forming units, IQR interquartile range, SD standard deviation

^aIn the antiseptic area (template window area, 25 cm²)

^bImmediately before preoperative skin antisepsis (first paint)

^cPathogen defined according to the National Healthcare Safety Network common commensals/pathogen list (version 9.2; www.cdc.gov)

^dInsufficient reduction was defined as detection of > 5 colony forming units and/or ≥ 1 pathogens in the examined, antiseptic area