The increasing prevalence of microbial strains exhibiting multidrug resistance as well as the surging pressure on healthcare systems worldwide have resulted in a veritable escalation over recent decades of nosocomial as well as community-acquired infections. Patients undergoing major surgical procedures, implantation of or interaction with medical devices, or patients with severe burns or chronic wounds, are particularly susceptible to microbial, notably bacterial and fungal, infections. Methicillin-resistant Staphylococcus aureus, Pseudomonas aeruginosa, as well as various yeast species of the genus Candida, are commonly associated with infected wounds and burns, often resulting in severe and complicated infections, placing additional burden on the healthcare system and on an already distressed patient.
Hygiene measures applied in healthcare settings, such as isolation of infected patients, improved surface sanitation, and the use of alcohol rubs and gels, undoubtedly mitigate the above problems to a certain extent, but adequate and efficacious wound care is a paramount determinant for preventing initial microbial colonization and subsequent spread of infectious diseases. Conventional wound dressings have long proved insufficient for treating, inter alia, severe burns and chronic wounds, with the implication that various types of antimicrobial dressings have been developed, comprising inter alia conventional antiseptics, antibiotics, antimicrobial peptides, or metallic agents with antimicrobial properties.
EP1274473, for instance, discloses antimicrobial coatings for wound dressings comprising a bioadsorbable substrate associated with one or more antimicrobial metals that releases said antimicrobial agent upon contact with an alcohol or water-based electrolyte. The bioadsorbable polymer is selected from a group comprising inter alia polyglycolic acid, glycolide, lactic acid, lactide, proteins, or polysaccharides.
The inherent antimicrobial properties of certain silver-containing compounds are being explored in various types of wound dressings. WO2002062403, inter alia, teaches a medical dressing comprising a complex of silver and being capable of releasing antimicrobial silver ion activity. More specifically, the silver complex comprises a combination of silver and a Group IV transition element, preferably zirconium, in order to enable controlled release of the silver ion to a wound bed.
US20030036717 describes an elastic compress consisting of an elastomeric matrix highly plasticized with a non-polar oil and containing a dispersed hydrocolloid. The compress additionally comprises at least one antiseptic agent, for instance a silver salt, and at least one surfactant for improving the bioavailability of the antiseptic agent.
Silicones are commonly utilized in various types of medical devices and in particular in wound dressings, as a result of its favourable intrinsic properties. Unlike many other materials used in wound dressings and medical devices, silicones possess attractive characteristics pertaining to inter alia manufacturing advantages, cohesion, tack, and adhesion, implying that they often constitute the materials of choice for wound dressing applications. WO1993019710 discloses an absorbent wound dressing comprising a layer of hydrophobic silicone gel, a layer of carrier material, and an absorbent body, providing a soft wound dressing having favourable properties relating to adhesive strength, ease of removal, and leakage prevention.
WO2008057155 discloses silicone gel forming compositions for temporarily adhering a medical device to a biological substrate, such as skin. Said disclosure teaches silicone gel compositions comprising active agents, for instance antibiotics, antiseptics, antifungals, anti-inflammatory agents, hormones, anticancer agents, histamine blockers, beta blockers, vitamins, sedatives, analgesics, proteolytic enzymes, and peptides, which can be bound in the composition. Further, WO2008057155 incidentally teaches including silver and derivatives as active agents that can be bound in the composition, but information about the parameters governing therapeutic efficacy, as well as efficacy validation, is largely absent.