In vitro Assay To Assess Biofilm Adherence

Abstract

BACKGROUND: Traditional microbiological methods to evaluate a medical device with antimicrobial properties are not necessarily indicative of their performance in vivo. OBJECTIVE: Researchers at Bacterin, Inc., have devised a dynamic in vitro model to examine biofilm development and assess the efficacy of anti-infective coatings on indwelling medical devices. This study explored the application of this technology on two anti-infective-coated Foley catheters. METHODS: Catheter samples, conditioned in human urine, were continually exposed to microorganisms and evaluated every 24 hours over a 7-day trial period. Clinically relevant urinary tract infection (UTI) pathogens were utilized with a daily average inoculum challenge of 10 3 CFU/mL. The biofilm was developed in a one-pass flow cell bioreactor under standardized, laminar flow conditions. Six different strains for each of the six pathogens were tested in triplicate. Traditional drop plate log count enumeration techniques were utilized. RESULTS: The silicone Foley catheter with anti-infective coating exhibited a statistically significant reduction in bacterial adherence for all organisms over the 7-day challenge. CONCLUSIONS: The in vitro biofilm assay offers a reliable alternative to traditional microbiological techniques. The assay detected significant differences among anti-infective properties for each catheter tested. Six strains for each pathogen were analyzed. The anti-infective coating contained on the silicone catheter outperformed the anti-infective coating on the latex Foley catheter. Clinical trials are encouraged to confirm in vitro results.