Blood culture isolates in hemodialysis vascular catheter-related bacteremia

Hemodialysis requires reliable and recurrent access to the central circulation and arteriovenous fistulas or grafts are the preferred modes of vascular access. However, in many patients the use of external tunneled vascular catheters may be necessary. The major complication of tunneled catheters is infection. Understanding local epidemiologic patterns of dialysis catheter-related bacteremia may help in the management of these patients. To address this issue, we reviewed the 5-year microbiologic culture results from all bacteremic hemodialysis patients with tunneled catheters at our institution. During this period, there were 203 organisms isolated from 153 positive blood cultures. Gram-positive, Gram-negative, and fungal species represented 55.7%, 43.3%, and 1% of isolates, respectively. Positive blood cultures classified according to the presence of a single Gram-positive or single Gram-negative organism, single fungus, or polymicrobial organisms, accounted for 41.8%, 29.4%, 0.6% and 28.1% of infectious events. From 2000-2004, there was a numerical trend toward a decrease in Gram-positive infection (64.3% versus 34.8% respectively, P = 0.12) and a numerical trend toward an increase in Gram-negative and polymicrobial bacteremias (17.9 versus 21.7, P = 0.07 and 17.9 versus 43.5, P = 0.09, respectively). These data indicate that bacteremic events in hemodialysis patients with vascular catheters are commonly due to a single Gram-positive organism, but the incidence of Gram-negative and polymicrobial bacteremia may be increasing. If confirmed in a prospective trial, adjustment of empiric antibiotic regimens for suspected catheter-associated bacteremia may be indicated.