What Is the Evidence for Silver Resistance in Chronic Wounds? A Systematic Review of Prevalence and In Vitro Studies

ABSTRACT

Silver‐containing wound dressings are among the most widely used topical antimicrobial interventions in chronic wound management. Amid escalating antimicrobial resistance and increasing scrutiny of antiseptic stewardship, there is growing debate regarding the prevalence and clinical relevance of bacterial resistance to silver, yet the available evidence has not previously been systematically evaluated with a specific focus on chronic wound populations. This review aimed to evaluate the published evidence on the prevalence of silver resistance in bacteria isolated from chronic wounds and to summarise experimental evidence on the capacity of wound‐associated isolates to acquire reduced silver susceptibility in vitro. We searched MEDLINE, Embase and Scopus in accordance with PRISMA guidelines, identifying 2190 records, of which five publications met eligibility criteria. Two publications investigating overlapping isolates were consolidated, yielding four independent datasets. Three prevalence datasets reported markedly different rates: studies from the United Kingdom and Sweden identified low phenotypic resistance (0 of 112 and 1 of 56 isolates) and sil gene prevalence (< 2% in both), while a study from Bangladesh reported substantially higher phenotypic resistance (31.5%) and sil carriage (30.9%). Regional differences in antibiotic use offer a plausible explanation but were not directly tested in any included study and concordance between genotypic and phenotypic resistance was poor throughout. Two in vitro induction studies produced divergent results by endpoint: reduced planktonic susceptibility reverted towards baseline once silver exposure was withdrawn, whereas substantial increases in biofilm eradication concentration in Pseudomonas aeruginosa persisted. Prevalence was low where examined, but three datasets from three countries cannot establish the global burden of silver resistance in chronic wounds and critical gaps remain in geographic representation, methodological standardisation and validated breakpoints. Current evidence is insufficient to support changes to guidelines or policy in either direction.