Effects of triclosan incorporation into ABS plastic on biofilm communities

Objective: This study compared the attached biofilm populations on acrylonitrile-butadiene-styrene (ABS) plastic with and without the incorporation of the antimicrobial triclosan [5-chloro-2-(2,4-dichlorophenoxy) phenol] after 1-3 weeks of exposure to drinking water. Methods: Biofilms were cultivated on triclosan-incorporated (TP) and control plastics (CP) in continuous flow culture reactors with drinking water as the growth medium and inoculum. After 1-3 weeks of exposure, the plastics were removed and the biofilms aseptically harvested. The attached communities were examined with respect to direct cell counts, culturability, triclosan resistance and community composition. Results: Based on these analyses, no significant differences were observed between the populations attached to TP and CP surfaces. Results from both a bioavailability assay and gas chromatography mass spectrometry analyses, revealed that only trace amounts of triclosan desorbed from the plastic. The lack of biofilm community difference, coupled with this limited desorption of triclosan from the TP indicates that the ABS plastic studied was no more effective at controlling bacterial populations than the control plastic because the antimicrobial was not bioavailable. Conclusions: These results call into question the long-term utility of triclosan incorporation into ABS plastic and highlight the need for proof of efficacy regarding the antimicrobial properties of such materials.