title: The antimicrobial efficacy of a silver alginate dressing against a broad spectrum of clinically relevant wound isolates.
abstract: Wound dressings impregnated with silver have a role to play in aiding to reduce both the dressing and wound microbial bioburden. It is therefore imperative that antimicrobial wound dressings have efficacy on a broad range of clinical significant microorganisms. Accordingly, this study aimed to determine the antimicrobial efficacy of a silver alginate dressing against 115 wound isolates that had been isolated routinely from patients at West Virginia University Hospital. Standardised corrected zones of inhibition (CZOIs) were performed on all clinical isolates. It was found that the silver alginate dressing was able to inhibit the growth of all microorganisms tested. In particular, the silver alginate dressing inhibited the growth of Candida albicans and yeasts with CZOI of 3-11·5 mm. All meticillin-resistant Staphylococcus aureus (MRSA) strains were found to be sensitive to the silver alginate dressing with a CZOI range calculated at 3-7·8 mm. Sensitivity to the silver alginate dressing was also evident for S. aureus and vancomycin-resistant Enterococci. CZOIs of 4·25 mm were calculated for Enterococcus faecium and 9·8 mm for viridans streptococcus. The bacteria which demonstrated the highest tolerance to ionic silver included Enterobacter cloacae and Acinetobacter baumannii. Contrary to this the most responsive microorganisms to ionic silver included strains of staphylococci, viridans streptococcus and Candida albicans. No antibiotic-resistant isolates, as identified by Kirby Bauer Clinical Laboratory Standards Institute classification system, were found to be resistant to ionic silver. When a selected number of microorganisms were grown in the biofilm phenotypic state enhanced tolerance to silver was observed, compared to their non biofilm counterparts. Overall, this study has demonstrated the broad antimicrobial activity of a silver alginate dressing on wound isolates grown in the non biofilm and biofilm state. This finding is clinically relevant as both the non biofilm and biofilm phenotypic states of microorganisms are evident in wounds and therefore significant to delayed healing. Consequently, it is imperative that antimicrobial wound dressings demonstrate antimicrobial activity against microorganisms in both phenotypic states.
authors.affiliation: Department of Pathology, Health Sciences Center, West Virginia University, Biofilm Laboratory, Morgantown, WV, USA. Steve.Percival@admedsol.com
authors.forename: Steven L
authors.initials: SL
authors.lastname: Percival
authors.forename: Will
authors.initials: W
authors.lastname: Slone
authors.forename: Sara
authors.initials: S
authors.lastname: Linton
authors.forename: Tyler
authors.initials: T
authors.lastname: Okel
authors.forename: Linda
authors.initials: L
authors.lastname: Corum
authors.forename: John G
authors.initials: JG
authors.lastname: Thomas
mesh_terms: D000464:Alginates / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001458:Bandages; D018441:Biofilms / Q000187:drug effects; D052978:Disk Diffusion Antimicrobial Tests; D004352:Drug Resistance, Microbial; D020723:Glucuronic Acid / Q000494:pharmacology; D006090:Gram-Negative Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D006603:Hexuronic Acids / Q000494:pharmacology; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D018030:Silver Compounds / Q000494:pharmacology*; D014946:Wound Infection / Q000382:microbiology / Q000628:therapy
chemical_list: D000464:Alginates; D000900:Anti-Bacterial Agents; D006603:Hexuronic Acids; D018030:Silver Compounds; D020723:Glucuronic Acid