Source and route of microbial colonisation of parenteral nutrition catheters.

To assess the effectiveness of tunnelling the polyurethane venous catheter for parenteral nutrition in reducing the frequency of catheter microbial colonisation, and to investigate the routes taken by microorganisms colonising the central venous catheter, 109 patients were randomised to traditional subclavian catheterisation (58, group A) or to subcutaneous catheter tunnelling (51, group B). Samples were taken from patients and their nurse attendants to identify their indigenous flora. Cultures were also done of swabs from the catheter insertion site, blood, nutrient solution, segment of the catheter, and washings of the catheter hub. Intravascular segment colonisation was commoner in group A (18/58) than in group B patients (4/51), and bacterial migration from insertion site to intravascular segment was also commoner among group A (9/58) than among group B patients (1/51). Catheter hub contamination was responsible in 10 out of 22 cases of microbial colonisation; in 6 of these 10 the bacterium isolated was present on the skin of nurses who changed the bag. Contamination of the insertion site skin and of the CVC hub were equally responsible for the microbial colonisation of the intravenous segment of the catheter.