Central venous catheters (CVCs) are indispensable in modern medical practice. Serious complications associated with CVC use include catheter-related infection (CRI) and catheter related-bloodstream infection (CRBSI) both of which contribute to morbidity, mortality and healthcare costs. Several studies have shown that implementation of basic hygiene routines, for CVC insertion and care, can significantly reduce the number of CRBSIs. However, there are limited data on the long-term effects after such an intervention. CVC infections, in terms of incidences and microorganisms, vary between different units and countries. Studies from Scandinavian hospitals are rare and not published recently. It has been stated that arterial catheters (ACs) are less prone to be responsible for CRI and CRBSI when compared with CVCs. However, recent studies outside Scandinavia have shown that they cause infections in significant numbers. The general view has been that nosocomial Candida infections in ICU patients evolve from the patient’s endogenous flora. However, a few studies have indicated that transmission of Candida spp. can occur between patients on an ICU as is well-described for certain bacteria. Candida spp. are among the most common microorganisms responsible for CRI/CRBSI.

The aim of this thesis was to study the incidences of, and microorganisms related to CVC (Study 1) and AC (Study 2) infections after implementation of evidence-based routines for insertion and care. The populations studied were patients with CVCs treated throughout the entire hospital (Studies 1 and 4) and patients with ACs treated on the ICU (Study 2). The aim was further to analyse risk factors contributing to these infections (Studies 1, 2 and 4). We also evaluated the long-term effects and endurance, of evidence-based routines, assessed as temporal variations in CVC colonisation and infections over a six-year period (Study 4). As we found that Candida spp. were common causes of CRI/CRBSI in Study 1, we decided to see if transmission of Candida spp. possibly occurred between patients on our ICU (Study 3).

We found low incidence rates, compared to international studies, for CRI and CRBSI related to the 495 CVCs studied over a short period (16 months, Study 1) and the 2045 CVCs studied over long-term follow-up (six years, Study 4). We found no cases of AC-CRBSI but a low number of AC-CRI in the 600 ACs studied. The type of microorganisms responsible for infections related to CVCs and ACs were similar to those found in international studies. However, the proportion of Candida spp. was high in Studies 1 and 4 evaluating CVC infections. There was no difference in the CVC-catheterisation time for CRI/CRBSI caused by Candida spp. as compared to CRI/CRBSI caused by bacteria. Risk factors for CRI associated with CVCs were chronic haemodialysis (Study 1), all haemodialysis in general (Study 4) and CVCs inserted via the internal jugular vein as compared to the subclavian vein (Study 4). Risk factors for CRI related to ACs were colonisation or infection of a simultaneous CVC and immunosuppression. Genotypes of Candida albicans and Candida glabrata had a heterogeneous distribution between ICU patients over time. Comparison with a reference group and cluster analysis indicated that transmission of Candida spp. between ICU patients is possible.

In, conclusion, we have found, after implementation of evidence-based routines for CVC and AC insertion and care, low incidences of CRI and CRBSI associated with these catheters. Furthermore, we found that transmission of Candida spp. between patients on the ICU is possible.