Reduction of Extraluminal Bacterial Colonization Using Chlorhexidine Antimicrobial-coated PICC Catheters in a Clinically Simulated Ovine Model (Pilot Study)

Background: The risk of catheter-related bloodstream infection (CRBSI) with use of the peripherally inserted central venous catheter (PICC) in hospitalized patients is reported to be similar to conventional central venous catheters. Both the internal and external surfaces of vascular catheters are vulnerable to microbial attachment and biofilm formation. The skin is the primary source of microorganisms colonizing the extraluminal surface. Attachment of bacteria occurs during the insertion of the catheter through the skin or with post-insertion migration through the subcutaneous tract. The use of antimicrobial-coated catheters is among the recommended strategies to reduce catheter colonization and CRBSI.

Objective: The purpose of this pilot study was to determine the effect of a chlorhexidine (CH) coated PICC compared to a non-coated PICC catheter on the reduction of extraluminal colonization in an ovine model.

Methods: Each of eight sheep were randomized to control (non-coated catheter) or treatment group (CH-coated catheter). Each sheep received 2 catheters, one in each jugular vein.  All catheters were inserted through disinfected skin inoculated with 10⁶ Staphylococcus aureus. Catheters were heparin locked for the 10-day study.  Sheep were euthanized and catheters were removed within the vessel by enbloc dissection at 10 days or after fever ³ 105° F for 2 days. Outcome measures included temperature, white blood cell count, peripheral blood culture, insertion site skin cultures, colonization of the skin and subcutaneous tissue, catheter segment colonization, and scanning electron microscopy and confocal laser microscopy of extraluminal catheter surfaces.

Results: Six catheters in the control group were removed due to fever and no catheters were removed for fever in the treatment group. On gross examination, extensive inflammation of the vessel wall, cellulitis of the surrounding tissue, and catheter-related thrombus was observed in the control catheters while all vessels and tissue appeared normal in the treatment group.  Mean log bacterial colonization counts of the control catheter were: tip segment 3.42 CFU/cm², vessel entry segment 4.22 CFU/cm², and segment within the skin 4.42 CFU/cm². Mean subcutaneous tissue counts were 5.47 CFU/g and mean skin counts were 6.55 CFU/g.  Mean log counts of CH-coated catheter segments were: tip segment 2.58 CFU/cm², vessel entry segment 1.68 CFU/cm², and skin segment 2.16 CFU/cm². CH-coated catheters subcutaneous tissue counts were 4.12 CFU/g and skin 3.92 CFU/g. The results of pooling the data for all samples indicated a 1.64 log reduction for the CH-coated catheter (p = 0.01) and a 1.78 log reduction for the tissue (p = 0.01).

Conclusions: The chlorhexidine coated PICC catheter resulted in a significant reduction in intraluminal colonization and infection compared to the non-coated PICC catheter.