TABLE 1.

MRSA strains analyzed in this study.

Strain	PFGE typea	Maximum biofilm induction in sub-MIC methicillin (A620 nm)b	Sensitivity to 0.7 μg/ml methicillin(ΔA450 nm)c	Methicillin concentration at maximum biofilm induction (μg/ml)
GW06	n.d.	21.0*	0.09	3.9
NRS751	USA100	20.8*	0.15	2.5
GW05	n.d.	19.4*	0.09	3.9
NRS702	USA300	18.8*	0.11	3.2
NRS716	USA300	18.3*	0.11	3.2
NRS715	USA600	18.1*	0.04	6.0
NRS745	USA1000	18.1*	0.09	3.5
NRS739	USA300	17.8*	0.11	4.2
NRS678	USA500	17.3*	0.07	4.3
NRS685	USA500	16.8*	0.12	3.0
NRS670	USA100	16.6*	0.12	2.5
NRS645	IBERIAN	16.5*	0.09	3.7
LAC	USA300	16.2*	0.09	2.5
GW11	n.d.	16.2*	0.04	2.8
NRS123	USA400	15.6*	0.07	4.2
NRS648	USA600	15.5*	0.20	1.0
NRS686	IBERIAN	15.4*	0.07	3.9
GW07	n.d.	15.3*	0.15	1.4
NRS643	USA300	15.1*	0.10	3.5
NRS734	USA800	14.9*	0.15	2.1
NRS689	USA700	14.7*	0.09	6.0
NRS732	USA300	14.4*	0.07	2.8
GW10	n.d.	14.3*	0.12	3.5
NRS714	USA800	14.3*	0.07	3.7
GW02	n.d.	12.8*	0.10	6.0
NRS662	USA300	12.0*	0.11	4.0
GW03	n.d.	11.6*	0.04	6.0
NRS722	USA200	11.1*	0.11	3.3
GW12	n.d.	11.0*	0.11	5.6
NRS484	USA1100	8.2*	0.02	6.3
GW01	n.d.	6.4*	0.06	5.3
NRS717	USA100	5.3*	0.06	5.0
NRS483	USA1000	5.1*	0.07	4.6
NRS723	USA100	4.4*	0.09	5.7
NRS651	USA200	2.7	0.04	4.9
GW09	n.d.	2.5	0.02	6.0
GW08	n.d.	2.5	0.03	6.0
GW04	n.d.	1.7	0.01	6.0
NRS701	USA200	1.6	0.07	5.0
NRS100	USA300	1.1	0.01	4.9

^an.d., not determined.

^bMaximum A_{620 nm} value in the crystal violet binding assay. *, significantly different from no antibiotic control (P < 0.05).

^c(A_{450 nm [no antibiotic]}) – (A_{450 nm [0.7 μg/ml methicillin]}).