Organism-specific bacteremia by hemodialysis access.

Abstract

Data on hemodialysis (HD)-related organism specific bacteremia rates by type of access over an extended period are scant in the literature. Using a registry data base we examined all positive blood cultures by organisms for each type of HD access over 14 years. The IRB-approved registry data collection of prevalent patients at our HD unit from 1/1/1999 through 12/31/2012 was analyzed. All positive blood cultures were recorded and expressed as episodes/1,000 days by access type: arteriovenous fistula (AVF), arteriovenous graft (AVG), and central venous catheter (CVC). The rate of positive blood cultures in patients with CVCs was 1.86/1,000 days and was much higher than in patients with an AVF (0.08/1,000 days, p<0.001) or an AVG (0.31/1,000 days, p<0.002). There was considerable fluctuation in the bacteremia rate in CVCs with a spike during 2004-2008, due predominately to coagulase-negative staphylococcus (CNS) bacteremia. The rate subsequently decreased after retraining of staff. The exit site infection (ESI) rate of CVCs was low, suggesting this was not contributing to the cause of the increase rate of CNS bacteremia. Those patients using a CVC had a markedly increased risk of multiple episodes compared to those using an AVF. Bacteremia with Pseudomonas, polymicrobial, and fungal organisms occurred only in those with a CVC. The frequency and type of positive blood culture in HD patients are highly associated with type of access used. The high rate of CNS bacteremia with CVC in conjunction with low ESI rate suggests that contamination at the time of accessing the catheter may be the problem. Staff training was followed by a decrease in infection rates. Trending organism-specific bacteremia infection rates in HD units may provide important clues to bacteremia causality and thus prevention.