Obtaining vascular access by catheterisation is a good option, especially in patients with vascular system fragility. In the authors' department, there was an increase in Gram Negative Bacillus (GNB) infection in patients with long term catheters (LTC). An objective was set to design an action plan and a new working methodology in order to eradicate the infection and the cause. Three periods were established in the prospective follow-up of LTC patients: the pre-epidemic period (01/94 to 03/99), with a bacteraemia every 144 days per patient, the epidemic period (04/99 to 12/00) with a bacteraemia every ten days per patient, and the post-epidemic period (01/01 to 04/02). A multidisciplinary working group was established, which produced action plans for nursing and technical staff. The working methodology of the service was studied and analysed by means of a review. The deionised water cultures at the entrance to the haemodialysis ward were negative. The dialysis and connector cultures were positive for GNB, confirming that they were of the same genetic origin. An evaluation of the periods was carried out, studying the working methodology, to which no changes were made between the pre-epidemic and epidemic period. In the post-epidemic period, a number of changes were made to the care dynamic, with no other bacteraemia arising to date. Adapting and improving protocols is a good indicator of quality. The role of nursing staff is vital in prevention of GNB.