Bacterial colonization of intravenous catheter materials in vitro and in vivo.

Four different intravenous catheter materials, brands Teflon, Silastic, Vialon, and Tecoflex, were evaluated in vitro for bacterial adherence after 2 and 24 hours' incubation in trypticase soy broth and after 2 hours' incubation in nutrient-free phosphate buffer (pH 7.2). The organisms used were Pseudomonas aeruginosa, Enterobacter aerogenes, Escherichia coli, and Staphylococcus epidermidis. The significant differences in in vitro adherence of the different bacterial species to the various catheters were then evaluated in vivo by intravenous injection of a single bolus of 1 X 10(5) organisms via tail vein of rats with previously placed catheters in their superior venae cavae. There was no association between the in vitro bacterial adherence and the tendency of the in vivo catheters to become colonized. Results of scanning electron microscopy of clean catheters and those removed from the rats showed obvious differences in surface characteristics and in clot adhesion between the catheters. These characteristics did not correlate with bacterial adherence in vitro or colonization in vivo. It is concluded that laboratory studies of bacterial adherence to, physical characteristics of, and thrombogenicity of intravenous catheters do not necessarily translate into resistance to clinical catheter sepsis.