An injury to the human body initiates a wound healing chain reaction that occurs in four sequential but overlapping phases: hemostasis, inflammatory, proliferative and maturation. This post focuses on the second (inflammatory) phase, which begins after blood flow stops (i.e., hemostasis) and...
Wound healing is often accompanied by bacterial infection. Many clinicians use antibiotics to treat wound infections. However, the overreliance on antibiotics is becoming an increasing concern for many global health organizations because it contributes to widespread antibiotic resistance.1 Excessive use of synthetic antibiotics leads to drug resistance, which poses a substantial threat to human health.2
This emerging health threat has led many health organizations to adopt antimicrobial stewardship programs that incorporate multiple strategies that slow the development and evolution of antibiotic-resistant pathogens. A core component of many antimicrobial stewardship programs is treating conditions without using antibiotics when it can be done safely and without jeopardizing the patients' health.
Antimicrobial Dressing Types
Topical and oral antibiotics are often the first line of defense when addressing a potential infection. However, several types of dressings can aid in the prevention and mitigation of an infection as well as or better than an antibiotic.
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Hydrogel-based wound dressings: These dressings mitigate bacterial infection and have proved to be an effective treatment for wounds. Many hydrogels originate from natural polymers and have broad-spectrum antibacterial activities.2 These dressings promote a moist healing environment. They can absorb exudate and support cellular migration and proliferation, allowing regeneration of lost tissue and the progression of healing.3
Silver nanoparticles: Silver is considered an important antibacterial agent for infections occurring in a variety of wounds. Silver has been recognized as an effective bactericide for millennia, and its use can be documented back to 1000 BC. Although silver is a mostly-inert metal, when it is exposed to wound exudate, it is easily ionized and turns into an extremely reactive agent that sticks to proteins and cell membranes. Silver ions kill microorganisms and damage them by poisoning the respiratory enzymes and the microbial electron-carrying sections and also by disabling various DNA activities. Silver also hampers microorganism replication. Given that silver is highly effective at treating infections, silver nanoparticles have been widely adopted in polymeric materials developed for wound dressings.3 There has been rising concern in recent years, however, over the possibility of silver resistance. A study presented in 2015 discovered two strains of silver-resistant bacteria, which may promote the use of non-silver antimicrobial dressings.4
Dialkylcarbamoyl chloride (DACC)–coated dressings: DACC-coated dressings irreversibly bind bacteria that exhibit high cell surface hydrophobicity (CSH) at the wound surface. When the dressing is changed, the bacteria are removed from the wound environment.5 They are removed without disrupting the bacterial cell wall, thereby avoiding the resultant increase in inflammation that often occurs with the use of traditional antibiotics or antiseptics. Numerous microorganisms with CSH have been shown to attach to DACC-coated materials.6
Polyhexamethylene biguanide (PHMB): PHMB, also called polyhexanide, is a cationic and highly water-soluble polymeric agent with broad-spectrum antimicrobial activity. It is used in many different products, including skin disinfectant solutions and wound dressing materials. It is also used in the management of both acute and chronic wounds.7 PHMB promotes contraction and aids in wound closure.8
Gentian violet: Gentian violet is a triarylmethane dye with antibacterial, antifungal, and immunotherapeutic properties. It works to hinder mitochondrial activity, decrease energy supply potential, and cause microbial death. It is highly effective against gram-positive microbes. When used in conjunction with methylene blue it can have a variety of effects on wounds, including exudate wicking, debridement, enhanced re-epithelialization, prevention of epibole, pain relief, and antimicrobial action without systemic absorption.9
Metal oxides: Along with silver, nanoparticles made with certain metal oxides, including iron oxide and zinc oxide, can act as antimicrobial agents coupled with biopolymeric nanofibers. For instance, zinc oxide has an antimicrobial effect along with the ability to induce proliferation of fibroblasts and angiogenesis.2 In recent years, biomedical applications using cobalt, copper, and zinc-based materials have reported antimicrobial effects.7
Medical-grade honey: Medical-grade honey also demonstrates remarkable antimicrobial, anti-inflammatory, and antioxidant performance. Honey is acidic, allowing it to acidify the alkaline medium of chronic wounds and stimulate wound healing. Honey is also able to help repair skin by encouraging the release of cytokines and stimulating the immune system response combatting the infection.8
The Future of Dressings and Their Role in Combating Wound Infection
Antimicrobial resistance will likely remain one of the top emerging health risks threatening the human population in the near and long-term future. Reducing the use of antibiotics in wound care is especially challenging because many wound infections are polymicrobial and require broad-spectrum antibiotics. Additionally, many complex wounds have recurrent infections and require multiple courses of antibiotic therapy.8
Advanced wound dressings using a variety of synthetic, natural, and hybrid compositions will play an increasing role in treating and preventing wound infection in the future. These dressings have the potential to become ideal candidates for the delivery of beneficial molecules and/or drugs directly to the wound site.9 The benefits of these materials are widespread, although their antimicrobial properties are key in addressing wound infections and their related complications.
1. Centers for Disease Control and Prevention. About antibiotic resistance. 2020. https://www.cdc.gov/drugresistance/about.html. Accessed February 25, 2021.
2. Zhong Y, Xiao H, Seidi F, Jin Y. Natural polymer-based antimicrobial hydrogels without synthetic antibiotics as wound dressings. Biomacromolecules. 2020;21(8):2983-3006.
3. Homaeigohar S, Boccaccini AR. Antibacterial biohybrid nanofibers for wound dressings. Acta Biomater. 2020;107:25-49.
4. Totty JP, Bua N, Smith GE, et al. Dialkylcarbamoyl chloride (DACC)-coated dressings in the management and prevention of wound infection: a systematic review. J Wound Care. 2017;26(3):107-114.
5. Finely PJ, Norton R, Austin C, et al. Evidence of emergent silver-resistance in clinical bacteria: a major implication for wound care and the use of silver-dressings. Poster presented at the Symposium on Advanced Wound Care, Spring 2015.
6. Totty JP, Harwood AE, Cai PL, et al. Assessing the effectiveness of dialkylcarbamoylchloride (DACC)-coated post-operative dressings versus standard care in the prevention of surgical site infection in clean or clean-contaminated, vascular surgery (the DRESSINg trial): study protocol for a pilot feasibility randomized controlled trial. Pilot Feasibility Stud. 2019;5:11. https://doi.org/10.1186/s40814-019-0400-2.
7. Yuan Y, Wu H, Lu H, et Al. ZIF nano-dagger coated gauze for antibiotic-free wound dressing. Chem Commun (Camb). 2019;55(5):699-702.
8. Hill R, Rennie MY, Douglas J. Using bacterial fluorescence imaging and antimicrobial stewardship to guide wound management practices: a case series. Ostomy Wound Manage. 2018;64(8):18-28.
9. Negut I, Grumezescu V, Grumezescu AM. Treatment strategies for infected wounds. Molecules. 2018;23(9):2392.
The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, Kestrel Health Information, Inc., its affiliates, or subsidiary companies.
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