Table 4.

Plateau uptake levels and critical adhesion forces derived from exponentially fitting the relation between bond-matured adhesion forces and uptake of calcein and dihydrostreptomycin.

	S. aureus RN4220	S. aureus RN4220 ΔmscL	t, df
Calcein uptake
Plateau fluorescence (%)	66 ± 16	40 ± 9***	4.166, 16
Critical force Fc (nN)	4.0 ± 2.5	1.2 ± 1.8*	2.727, 16
Dihydrostreptomycin uptake
Plateau killing (ΔLog CFU mL−1)	−2.3 ± 0.4	−1.0 ± 0.2**	5.035, 4
Critical force (nN)	3.5 ± 5.3	Independent of adhesion force	–

Plateau levels for the percentage of fluorescent staphylococci after calcein uptake and the CFU reduction due to dihydrostreptomycin uptake and critical adhesion forces for each of the two staphylococcal strains used. ± signs represent standard deviations over nine different fluorescence images obtained from three different bacterial cultures for calcein uptake, and three measurements from three different bacterial cultures for dihydrostreptomycin uptake. * indicates significant differences from S. aureus RN4220 (two-tailed Student’s t-test, *p < 0.05, **p < 0.01, ***p < 0.001). t-values and degrees of freedom (df) of the Student’s t-test are indicated in the last column.