The Effect of Chlorhexidine Antimicrobial Coating on the Reduction of Intraluminal Catheter Biofilm Formation in a Clinically Simulated Ovine Model (Pilot Study)

Background: The hub and intraluminal surfaces of vascular catheters are a major source of catheter-related bloodstream infection (CRBSI) particularly in catheters indwelling for greater than 5-7 days. The use of peripherally inserted central catheters (PICC) in inpatient settings has been challenged due to reports documenting PICC CRBSI rates to be similar to short-term percutaneous and greater than long-term tunneled central venous catheters. The use of PICC catheters with an antimicrobial coating on the intraluminal catheter surface and within the catheter hub may reduce infection risk.

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

Methods: Each of 8 sheep were randomized to control (non-coated catheter) or treatment group (CH coated catheter). Each sheep received one catheter inserted into the jugular vein. The insertion protocol included chlorhexidine gluconate (CHG) skin cleansing, 2% CHG/70% IPA (isopropyl alcohol) skin disinfection, maximum sterile barrier, CHG foam disc and gauze dressing. Post-operatively catheters were locked with a 10⁶ Staphylococcus aureus inoculum for three hours and the inoculum was then removed. Catheters were infused daily with Lactated Ringer’s solution over 8 hours for 7 days and removed on Day 8. Outcome measures included temperature, white blood cell count, catheter blood culture, intraluminal catheter segment colonization (including connector, hub, catheter extension tubing, and catheter segments), scanning electron microscopy and confocal laser microscopy of intraluminal catheter surfaces.

Results: One control catheter was removed due to the sheep experiencing fever of >105°F for two days.  All blood cultures from the treatment catheters returned to and remained negative after the positive post inoculation catheter blood culture.  All catheter blood cultures (except for one sheep) in the control group increased to ³ 10⁵ CFU/ml within 8 days.  No chlorhexidine coated catheters had to be removed from sheep due to infection.  Average log bacterial colonization counts of control non-coated catheter samples were 3.74 CFU/cm² at the tip, 1.43 CFU/cm² in the middle, 1.57 CFU/cm² in the extension tubing and 2.05 CFU per hub.  Average log bacterial colonization counts of chlorhexidine coated catheter samples were 0.30 CFU/cm² at the tip, middle, and extension tubing, while the hubs had an average of 0.57 CFU. The data were pooled for all segments sampled for each catheter and the results indicated an overall 2.91 log reduction with a p value of 0.02.

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