Effect of antibiotics on the adhesion to human fibronectin. Exponential growth cultures of S. aureus laboratory strains 8325-4 and DU5883 and clinical isolates ST2008 1028, ST2008 0563, HT2000 0594 and HT2001 0390 were treated or not treated with 1/2 of the MIC of antibiotics (oxacillin, moxifloxacin, clindamycin, linezolid or rifampicin) and assayed for adhesion to fibronectin-coated microplates, as described in Methods section. The results are OD570 nm values reflecting bacterial adhesion to fibronectin. The values were obtained from 3 different wells previously incubated with the same bacterial suspension, and adhesion is expressed as the mean ± standard deviation (dark bars for untreated cultures and white bars for antibiotic treated cultures; results from three different experiments). Asterisk = significantly different from the control (corresponding isolate grown without antibiotic), with a P value of 0.05 by one-way analysis of variance followed by a posteriori Dunnett's test.