FIG. 4.

Aryl rhodanines inhibit primary adhesion. (A) Aryl rhodanines inhibit attachment of S. aureus ATCC 35556 to tissue culture-treated polystyrene in a static assay. A mid-log-phase culture was harvested, resuspended in PBS to an OD₆₀₀ of 0.5, and aliquoted. Aryl rhodanines were added to aliquots to achieve various concentrations (0× to 8× the MBIC), which were then transferred to 96-well tissue culture-treated polystyrene assay plates and incubated at 37°C for 30 min. After repeated washing, adherent cells were stained with BacLight Live/Dead stain (Molecular Probes) and fluorescence emission (excitation wavelength, 485 nm; emission wavelength, 530 nm) was measured to quantify adherent cells. Each bar represents the average of at least eight assay wells, and the error bars represent the standard deviation. The asterisks indicate a statistically significant difference between the untreated control and a treated sample determined with a two-tailed Student t test (*, P ≤ 0.05; **, P ≤ 0.001). (B) Pretreatment of S. aureus ATCC 35556 with aryl rhodanines inhibits primary attachment. A cell suspension was prepared as described above and pretreated with aryl rhodanines for 30 min. Cells were harvested to remove free compound, resuspended in PBS, and used in an adhesion assay as described above. (C) Aryl rhodanines inhibit attachment to PVC in a static assay. The assay described in panel A was used to measure adhesion to PVC. (D) Aryl rhodanines inhibit attachment to silicone disks in a static assay. The assay described in panel A was used to measure adhesion to medical grade silicone disks. Each bar represents the average of three silicone disks, and the error bars represent the standard deviation. (E) MBX-1240 inhibits attachment to silicone disks in the presence of shear force. Cell suspensions containing various concentrations of MBX-1240 were prepared as described above, transferred to a culture tube containing a silicone disk, and incubated at 37°C with moderate shaking. After repeated washes, the disk was transferred to a fresh tube and adherent bacteria were removed by sonication. The numbers of adherent bacteria were determined by plating appropriate dilutions and counting colonies. Each bar represents the average value obtained from two silicone disks. Light and dark bars represent log₁₀ CFU/disk and fraction of control, respectively.