Disruption of biofilms associated with vascular catheterization

Abstract

ISSUE: Biofilms are of great concern to patients who are vascular-catheterized. Of the more than 20 million vascular catheterizations performed in the United States every year, almost all of them become infected with biofilms. The FDA requires all patient preoperative skin preparation products to demonstrate efficacy versus Staphylococcus epidermidis , but only in its planktonic state. Biofilms are from 500 to 1500 times more resistant to antibiotic therapy than are planktonic forms. Hence, the question arises as to how effective against biofilms are topical antimicrobials. PROJECT: The evaluation consisted of comparing the bactericidal effectiveness of a new topical antiseptic product (alcohol-based ZPT) versus planktonic Staphylococcus epidermidis and a biofilm formed of the same species. Planktonic time-kills were performed to test the efficacy of the product versus Staphylococcus epidermidis . For the biofilm challenge, biofilms were developed on microporous membranes resting on agar nutrient medium. The membranes were inoculated and incubated at 35° ± 2°C for 48 hours, with transfers to fresh agar nutrient medium every 10-12 hours. After 48 hours, the membrane-supported biofilm was exposed to the alcohol-based ZPT product for 15 seconds and 2 minutes in screw-caped containers. Following each exposure time, neutralizing fluid was transferred into the jars. The neutralizer/product/disaggregated biofilm suspension was then serially diluted, plated, and incubated at 35° ± 2°C. RESULTS: The alcohol-based ZPT achieved a >5 log10 reduction versus planktonic bacteria at both the 15-second and 2-minute time point. The alcohol-based ZPT achieved only a .28 log10 reduction versus the biofilm in 15 seconds, but after 2 minutes the alcohol-based ZPT again achieved >5 log10 reduction versus the biofilm. LESSONS LEARNED: The biofilm was able to retard the rate of microbial action of the alcohol-based ZPT, relative to that demonstrated in the planktonic time-kill. However, the topical antimicrobial demonstrated a high antimicrobial activity against the biofilm well within a timeframe practical for site preparation. Use of alcohol-based ZPT to prepare skin sites prior to vascular catheterization offers promise of reducing catheter-associated infections by not only demonstrating very good kill against planktonic and biofilm Staphylococcus epidermidis , but by providing the known accumulative antimicrobial activity of ZPT to prevent rebound of skin colonization.