Pitfalls in efficacy testing – how important is the validation of neutralization of chlorhexidine digluconate?

Table 2 Suspension test for validation of neutralization of chlorhexidine digluconate.

Storage time	Test organism exposed to (name of the test)	Staphylococcus aureus	Staphylococcus epidermidis	Micrococcus luteus	Corynebacterium jeikeium	Candida albicans
<1 min.	neutralized antiseptic solution (neutralizer toxicity test)	1.82 ± 0.04	1.77 ± 0.03	0*	1.66 ± 0.09	1.06 ± 0.12*
	saline peptone water (organism viability test)	1.90 ± 0.05	1.84 ± 0.07	1.74 ± 0.03	1.79 ± 0.02	2.02 ± 0.03
3 h	neutralized antiseptic solution (neutralizer toxicity test)	1.80 ± 0.02	0.86 ± 0.14*	0*	1.44 ± 0.22*	0.13 ± 0.23*
	saline peptone water (organism viability test)	1.88 ± 0.06	1.81 ± 0.02	1.73 ± 0.05	1.77 ± 0.08	2.03 ± 0.02

Mean and SD of the number of CFU (log₁₀) when exposed to the neutralized antiseptic solution or saline peptone water at storage times of < 1 min and 3 h; * significant difference (p < 0.05) in comparison to organism viability test, Tukey-HSD

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