Bacterial colonization of epidural catheters used for short-term postoperative analgesia: microbiological examination and risk factor analysis.

Background: The authors conducted this prospective study to determine the incidence, potential routes, and risk factors of microbial colonization of epidural catheter used for postoperative pain control.

Methods: Two-hundred five patients with epidural analgesia for postoperative pain were studied. On removal of the catheter, five samples were sent for culture: the infusate, a swab from inside the hub of the epidural catheter connector, a swab from the skin around the catheter insertion site, the subcutaneous segment, and the tip of the catheter. Clinical data related to the catheter insertion, management, and general patient conditions were collected.

Results: The positive culture rates for the subcutaneous and tip segments of the catheter were 10.5% and 12.2%, respectively. The most common organism in the culture was coagulase-negative staphylococcus. There was a strong linear relationship between bacterial colonization in the skin around the catheter insertion site and growth from the subcutaneous and tip segments of catheter (P = 0.000). Catheter-related events at ward, blood transfusion, and positive culture from the skin at the insertion site were risk factors for bacterial colonization of epidural catheters. Inflammation at catheter insertion site, catheter indwelling time, and level of catheter insertion were not predicators for epidural catheter colonization.

Conclusions: The authors' results suggest that bacterial migration along the epidural catheter track is the most common route of epidural catheter colonization. Maintaining sterile skin around the catheter insertion site will reduce colonization of the epidural catheter tip.