Antimicrobial Activities of Iodinated Polystyrene Derivatives

Abstract

The antimicrobial activities of insoluble haloge‐nated acetamidomethyl‐styrene polymers (prepared by covalent bonding of iodine to polystyrene) were assessed as were the factors determining antimicrobial efficacy. The most active materials were selected from chlorinated or iodinated polymers. Antimicrobial activities were assessed for Escherichia coli (ATCC 25922; American Type Culture Collection, Rockville, MD, U.S.A.), Saccharo‐myces cerevisiae, and Candida albicans by determining time‐course changes in microbial counts in vitro. A 2‐iodoacetamidomethylstyrene polymer (No.6‐I:‐CH2I) was found to have the greatest antimicrobial activity against both bacteria and fungi. No.6‐1 is the first antimicrobial material that did not make an inhibition hollow in the conventional diffusion test or for which conjugated iodine showed antibacterial activity. This material can be introduced into styrene units on the surface of devices by chemical modification. This material was most active at 37oC. For coated dishes, antimicrobial activity depended on the depth or swollen character of the reactive layer. No.6‐1 requires not only a minimum width of polymer layer, but also frequent contact with microbes to have an antimicrobial effect. No.6‐1 is valuable as a new material because it has strong antimicrobial activity by itself but does not release active iodine. This material is expected to have various applications in implantable clinical devices.

Evaluation of the antimicrobial activity of cationic polyethylenimines on dry surfaces

“…Many researchers have relied upon a method similar to Method I where bacteria are applied by spraying and then surfaces are incubated under agar 1–3, 6, 8–10, 13, 16, 18, 23, 24. Others have incubated polymer‐modified surfaces/samples in a cell suspension with shaking4, 7, 25 or created a zone of inhibition within bacteria‐inoculated agar plates 26…”

“…The development of contact antimicrobial surfaces has advanced rapidly in recent years as the need for nonleaching methods for controlling antibiotic‐resistant bacteria has emerged. Such self‐sterilizing surfaces have employed polymers and copolymers containing N ‐alkylated poly(4‐vinylpyridine),1–3 N ‐alkylated poly(acrylic acid) derivatives,4 alkylammonium‐containing polyurethanes,5, 6 halogenated acetamidomethyl‐styrene polymers,7 and quaternized cationic polyethylenimines 8–10. Of these materials, the ability of both alkylammonium‐containing polyurethanes and quaternized polyethylenimines (PEI+) to be applied directly to substrates using a noncovalent paint‐like procedure is highly advantageous given the synthetic challenges of covalently attaching other antimicrobial polymeric coatings to surfaces such as glass,2, 4, 6, 9–16 plastic,1, 13, 17 cloth,18 and cellulose 4…”

The importance of fungal pathogens and antifungal coatings in medical device infections

“…Lin and co-workers reported on the use of polystyrene which was modified with various chlorinated or iodinated amides for antifungal applications (Lin et al, 1996). Importantly, these modified polystyrenes were tested for their ability to leach halogens, after sufficient washing cycles.…”