ADHESION OF STAPHYLOCOCCI TO POLYMERS WITH AND WITHOUT IMMOBILIZED HEPARIN IN CEREBROSPINAL-FLUID

Infections of cerebrospinal fluid (CSF) shunts constitute a serious cl inical problem. The role of adhesion by coagulase negative staphylococ ci, the most common etiological agent, was examined in vitro to polyvi nyl chloride (PVC), silicone, and to PVC and silicone with end-point a ttached (EPA) heparin. These are flexible materials commonly used in n eurosurgical implants. Bacterial adhesion was quantitated by biolumine scence. The bacterial adhesion to biomaterial surfaces increased with increasing concentrations of bacterial cells. Scatchard plot analysis showed continuous negative (concave) slopes, indicating multiple inter actions between biomaterial and bacteria. The thermodynamic studies sh owed a positive value of the standard entropy change at 37 degrees C, which indicates that hydrophobic interactions are important in bacteri al adhesion to polymers. Incubation with CSF for 1 h decreased bacteri al adhesion in 75% of the samples compared to incubation in buffer. Th us, the contribution of CSF proteins, like fibronectin, for the initia l bacterial adhesion might be small. Heparinization of silicone and PV C decreased the numbers of adhered bacteria by 23 to 54% and 0 to 43% compared to unheparinized surfaces. Among putative inhibitors tested, suramin, chondroitin sulfate, and fucoidan inhibited adhesion to 81 +/ - 19, 78 +/- 22, and 64 +/- 7%, respectively. These findings indicate that hydrophobic interactions play an important role, and heparinizati on rendering the biomaterial surface hydrophilic is therefore effectiv e to reduce bacterial adhesion. Heparinized polymers incubated with pu tative inhibitors may be the optimal way to prevent shunt infections. (C) 1997 John Wiley & Sons, Inc.