The Effect of Apo‐Transferrin on Bacterial Adhesion to Biomaterials

Apo‐transferrin (apo‐Tf), the iron deficient form of Tf, has been identified previously as a potent inhibitor of Staphylococcus epidermidis adhesion to polyurethane surfaces. In this study, the ability of apo‐Tf to suppress the adhesion of two other strains of bacteria, namely a Gram‐positive Staphylococcus aureus and a Gram‐negative Pseudomonas aeruginosa to several biomaterials, including polystyrene, polymethylmethacrylate, and silicone, is documented. The presence of apo‐Tf in the medium at 20 μg/ml lowered bacterial adhesion to all tested biomaterials more than fourfold. Moreover, apo‐Tf exerted its inhibitory activity even when protein coated surfaces were used as substrates for bacterial adhesion. To emphasize the importance of apo‐Tf in the prevention of bacterial adhesion, human serum was depleted of Tf, employing affinity chromatography, and was shown to lose its inhibitory activity toward bacterial adhesion. Upon addition of apo‐Tf to Tf‐depleted serum, the activity was reestablished, resulting in a marked reduction in the number of bacteria adhered to the surfaces. Following the enzymatic deglycosylation, apo‐Tf retained its ability to prevent bacterial adhesion. These results indicate that the carbohydrate moiety does not seem to play a role in this activity. The presented data provide the evidence that the inhibitory activity of apo‐Tf is not bacterial strain specific and that the presence of apo‐Tf in the medium results in a significant reduction of bacterial adhesion to a variety of neat and/or protein coated surfaces.