Catheter related blood stream infection (CRBSI) is the most important complication of central venous dialysis catheters. The risk of tunnelled line bacteraemia is around 1–3 episodes per 1,000 catheter days in most renal units. Tunnelled lines have lower rates of infection than temporary lines and jugular placement carries a lower risk than femoral. Bacteraemia is approximately ten times more common with lines than with fistulas and this is one of the reasons why a fistula is the preferred form of vascular access for haemodialysis. Tunnelled lines are also associated with significantly higher risks of death from infection than fistulas and grafts.

This diagnosis must be considered in all dialysis patients with a central venous catheter (CVC) who present with pyrexia or acutely raised inflammatory markers. Patients with CRBSI will classically present between dialyses with a rigor and a temperature of 39°. However, the presentation can be subtle and have only minor signs such as low grade fever, hypothermia, hypotension, loss of glycaemic control, lethargy and confusion. Less commonly patients will present with disseminated infection (e.g. discitis) from an untreated access infection.

Promptly, by simultaneous culture of blood from the line and the periphery before commencing antibiotic therapy. Blood culture from the line should be from the catheter hub after first removing the line lock i.e. you should discard about 3 ml before using a separate syringe for the culture. Clinical examination is usually unrevealing, which is often a pointer to the catheter as the source of infection (i.e. absence of other sources of infection). The exit site and/or tunnel are not always inflamed. Alternative sources of infection should be considered with a focussed history, examination, imaging (especially chest x-ray) and laboratory testing (urine culture if possible). You should also remember to check white cell count and CRP, and swab both the exit site and nose.

The great majority are staphylococci (Fig. 42.1). Coagulase negative staphylococci are usually regarded as skin contaminants when grown from peripheral blood cultures but may be pathogenic if isolated from a dialysis line or any patients with indwelling prosthetic material.

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