A prospective study of central venous hemodialysis catheter colonization and peripheral bacteremia

Background: Sepsis as a consequence of central venous hemodialysis catheter colonization is a major cause of morbidity in the hemodialysis population. We have previously shown that the majority of catheters become colonized and that this is associated with peripheral bacteremia. The time period over which this colonization occurs is unknown. Method: A prospective study of 31 central venous hemodialysis catheters was performed. Central venous blood cultures were taken from the catheter weekly after insertion. When the central cultures became positive, indicating catheter colonization, peripheral venous blood cultures were taken during dialysis to detect peripheral bacteremia. Results: Twenty-one catheters (68%) became colonized before their removal for reasons other than infection (mean time to colonization 27 days, range 5 - 115 days). Eleven patients (35%) developed peripheral bacteremia with the same organisms (mean time from colonization to bacteremia 32 days, range 5 -126 days). Bacteremia only occurred when blood drawn from the catheter cultured more that 3000 colony forming units per ml. Conclusions: Bacterial colonization of central venous catheters often leads to bacteremia. The time between insertion and colonization is very variable, but is universally present after 16 weeks. The risk of subsequent bacteremia is related not only to time left in situ, but also the degree of colonization. Surveillance cultures would allow clinicians to detect colonization before bacteremia occurs and take preventative measures.