Bacterial adhesion to intravenous cannulae: influence of implantation in the rabbit and of enzyme treatments.

Comparison was made of the adhesion of Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Klebsiella aerogenes and Pseudomonas aeruginosa to six types of intravascular cannula material. Adhesion to materials removed from rabbit tissues did not differ significantly between types of material or between bacterial species. In contrast, major differences were found when unimplanted materials were examined; the overall rank order of adhesiveness of bacteria to unimplanted materials (S. epidermidis greater than P. aeruginosa greater than S. aureus much greater than K. aerogenes greater than E. coli) was highly significant (F = 13.0, P less than 0.0005), and although no single material was consistently least attractive to all micro-organisms, FEP-Teflon and PTFE-Teflon showed significantly lower overall affinity for bacteria than other materials (P less than 0.001); all species showed a significant preference for a silicone polymer (P less than 0.0005). The nature of the bacterial surface structures responsible for adhesion were investigated by the actions of pronase and mixed glycosidase, which produced significant respective decreases and increases in adhesion of staphylococci to unimplanted materials; their effects on the Gram-negative bacilli were less consistent.