Table 2.

Phenotypic characteristics of S. aureus-derived variants obtained after serial passages in sub-inhibitory NaOCl concentrations.

Strain	NaOCl concentration (v/v)	Serial passage after	Colony morphology on CSA	Variant	MIC value for NaOCl determined after
					culture on CSA	1st passage in TSB	2nd passage in TSB
ATCC® 29213TM	0.005%	72 h	tiny, yellow, narrow hemolysis	SA29213-A	0.08%	0.07%	0.07%
	0.005%	72 h	tiny, yellow, very narrow hemolysis	SA29213-B	0.08%	0.07%	0.07%
	0.005%	72 h	medium-sized, lutescent, narrow hemolysis	SA29213-F	0.08%	0.09%	0.08%
	0.0025%	72 h	small, lutescent, no hemolysis	SA29213-E	0.08%	0.08%	0.07%
	0.0006%	72 h	convex, yellow, distinct hemolysis	SA29213-C	0.08%	0.08%	0.07%
	0.0025%	24 h	medium-sized, yellow, narrow hemolysis	SA29213-H	0.08%	0.07%	0.07%
	0.0025%	24 h	medium-sized, yellow, no hemolysis	SA29213-D	0.08%	0.08%	0.08%
	0.00125%	24 h	small, yellow, weak hemolysis beneath the colony	SA29213-G	0.07%	0.07%	0.09%
ATCC® 6538TM	0.01%	24 h	tiny, yellowish, no hemolysis	SA6538-a	0.1%	not done	not done
	0.005%	24 h	small, yellow, no hemolysis	SA6538-b	0.1%	not done	not done
	0.01%	72 h	small, convex, yellow, no hemolysis	SA6538-c	0.25%	0.1%	not done
	0.0025%	72 h	small, convex, yellowish, distinct hemolysis	SA6538-d	0.25%	0.1%	not done

At the end of each experiment (i.e. eight times serial subculture after 24 h and two serial subcultures after 72 h of incubation, respectively) subcultures were prepared on CSA from every tube showing bacterial growth. Cultures were grown at 37 °C for 24 h and colony morphology was assessed thereafter. Each colony with a different phenotype was separated on CSA. CSA – Columbia sheep blood agar (7% blood), NaOCl – sodium hypochlorite, MIC – minimum inhibitory concentration, TSB – tryptic soy broth.