Rising antimicrobial resistance in chronic wounds

Summary: Antimicrobial resistance (AMR) is a critical global public health threat, including multi-drug resistance in chronic wounds, and recently reported diminished efficacy of broadly used silver based dressings. We analyzed the prevalence of methicillin and mupirocin resistance genes in patients with chronic venous leg ulcers (VLU, n=24) without clinical infection signs. Methicillin-resistant <i>Staphylococcus aureus</i> was targeted due to its high AMR-related mortality, while mupirocin is the most prescribed topical wound antimicrobial. Results revealed a methicillin resistance rate of 66.67% and an alarming mupirocin resistance rate of 83.33%. We conducted a randomized controlled trial to compare efficacy of an antimicrobial silver-based dressing with a Dialkylcarbomoyl chloride (DACC)-based dressing, which eliminates bacteria through irreversible binding. 31 subjects were randomized to either group to receive 4 weeks of treatment, followed by a 2-week follow-up. Tissue samples were collected at weeks 0, 2, and 6, with bacterial load quantified using qPCR. DNA samples from week 0 and week 3 underwent 16s rRNA and metagenome sequencing. Inflammatory markers (CCL4, CXCL9, CXCL12, CCL13, ICAM-1, and VCAM-1) were analyzed in tissue. Subjects over 65 yo had a significantly higher bacterial load pre-intervention, correlating with increased AMR-related deaths in older adults. The silver-based dressing group showed a significantly higher bacterial load by third visit compared to the DACC, along with increased <i>Staphylococcus</i> and <i>Streptococcus </i>abundance. Healing rates were higher in the DACC group, with healers (≥50% wound size reduction) showing higher baseline tissue inflammation that reduced over time. Non-healers, particularly in the silver group, exhibited persistently low inflammation levels. Clinical data supported these findings, showing improved wound quality of life and pain in the DACC group. Our findings highlight the growing AMR in chronic wounds and the need for antimicrobial stewardship, accurate infection diagnosis, and novel treatment strategies to prevent AMR. Camile Delva¹, Tammy Gonzalez¹, Elina Zhivov¹, Jamie Burgess¹, Hadar Lev-Tov¹, Marjana Tomic-Canic¹, Irena Pastar¹ 1. University of Miami Miller School of Medicine, Miami, FL, United States. Clinical Research: Interventional Research