ReviewThe growing importance of materials that prevent microbial adhesion: antimicrobial effect of medical devices containing silver
Introduction
Antimicrobial polymers that contain silver represent a great challenge for academics and industry [1]. These materials capture attention because of their novelty in being a long-lasting biocidal material with high temperature stability and low volatility [1]. The large increase in the number and occurrence of antibiotic-resistant bacterial strains has prompted a renewed interest in the use of silver as an antibacterial agent [2].
Silver is a metal known for its broad-spectrum antimicrobial activity against Gram-positive and Gram-negative bacteria, fungi, protozoa and certain viruses [3], including antibiotic-resistant strains [2], [4]. It can be used to reduce infections in the treatment of burned areas [5], [6], [7], to prevent bacterial colonisation on medical devices [7], [8], [9], [10], [11], [12] as well as in textile fabrics [7], [13] and for water treatment [14]. Silver, as an antiseptic agent, has been effective in a variety of materials, including glass, titanium and polymers [15].
The antimicrobial activities of commercially available silver-impregnated dressings and catheters have been reported [8], [16], [17]. It has been suggested that impregnation of silver into a coating can be more effective than direct surface coating alone, since surface silver can be readily deactivated by protein anions [2], [18]. This impregnation of silver ions (SI) would also be beneficial in protecting the inner and outer catheter surfaces against bacterial attachment [2], [19].
However, the use of medical devices containing silver must be undertaken with caution, since a concentration-dependent toxicity has been demonstrated. Braydich-Stolle et al. [20] assessed the suitability of a mouse spermatogonial stem cell line as an in vitro model to assess the nanotoxicity of silver. Concentrations of silver nanoparticles (SN) between 5 μg/mL and 10 μg/mL induced necrosis or apoptosis of mouse spermatogonial stem cells [20]. Moreover, heavy metal accumulation in the environment has been mentioned in the US Agency for Toxic Substances and Disease Registry (ATSDR) Comprehensive Environmental Response, Compensation, and Liability Act 2007 Priority List [http://www.atsdr.cdc.gov/cercla/] as well as by the European Commission on heavy metals waste [21]. Nevertheless, silver has not been cited amongst the most prevalent heavy metals in the priority list of hazardous substances to public health [21].
Despite this, as the use of silver and the number of available silver-based products has increased, it is becoming important to clarify the efficacy of silver against different microorganisms and biofilms. It is also essential to answer questions related to the mechanisms of the various silver forms as antimicrobial agents as well as the dissociation of SI and the resulting antimicrobial efficacy. Thus, this literature review was carried out using references from the last 35 years regarding silver as an antimicrobial agent, specifically silver zeolite (SZ) and SN, SI release and biofilm formation.
Section snippets
Antimicrobial properties
Medical devices such as endotracheal tubes, vascular and urinary catheters, and hip prosthetics are responsible for over one-half of nosocomial infections in the USA [22], [23]. To create surfaces resistant to bacterial adhesion and colonisation, several methods of incorporating silver on medical devices have been described [3], [22], [23]. Silver has been used in ionised and elementary forms, as SZ or as nanoparticles.
Biofilm formation
Biofilms are defined as communities of bacteria that colonise surfaces in an aqueous environment [28]. Biofilm formation occurs as a result of a sequence of events: microbial surface attachment, cell proliferation, matrix production and detachment [45].
The conditioning film, formed by a layer of organic molecules adhered to the surface, is considered a precursor for the initial attachment of planktonic cells [28]. Once the microorganisms reach critical proximity to the surface, the
Conclusion
Silver antimicrobial agents have been pursued as an alternative strategy for reducing bacterial adhesion and to prevent biofilm formation. Antibacterial experiments demonstrated that silver is effective against a broad range of bacterial cells and mature biofilms, however the concentration is an important factor. The current review suggests that elementary silver, SZ and SN in polymers can constitute effective antimicrobial biomaterials for a variety of promising applications. Owing to the much
Acknowledgments
The authors are thankful to the Laboratório Interdisciplinar de Eletroquímica e Cerâmica, Universidade Federal de São Carlos (LIEC-UFSCar) for preparing the SN and performing the transmission electron micrograph and scanning electron micrograph investigations, as well as Jeremy Matis and Rosimeiri Dainez for the English review.
Funding: No funding sources.
Competing interests: None declared.
Ethical approval: Not required.
References (64)
- et al.
Silver ion release from antimicrobial polyamide/silver composites
Biomaterials
(2005) - et al.
Prevention of Staphylococcus epidermidis biofilm formation using a low-temperature processed silver-doped phenyltriethoxysilane sol–gel coating
Biomaterials
(2008) - et al.
Inhibition of bacterial adhesion on PVC endotracheal tubes by RF-oxygen glow discharge, sodium hydroxide and silver nitrate treatments
Biomaterials
(2004) - et al.
Comparison of silver-coated dressing (Acticoat), chlorhexidine acetate 0.5% (Bactigrass), and fusidic acid 2% (Fucidin) for topical antibacterial effect in methicillin-resistant staphylococci-contaminated, full-skin thickness rat burn wounds
Burns
(2005) - et al.
Effect of silver-coated urinary catheters: efficacy, cost-effectiveness, and antimicrobial resistance
Am J Infect Control
(2004) - et al.
Use of an oxonol dye in combination with confocal laser scanning microscopy to monitor damage to Staphylococcus aureus cells during colonisation of silver-coated vascular grafts
Int J Antimicrob Agents
(2004) - et al.
Silver coated materials for external fixation devices: in vitro biocompatibility and genotoxicity
Biomaterials
(2002) - et al.
Antibacterial activity of dentine primer containing MDPB after curing
J Dent
(1998) - et al.
Impact of heat on nanocrystalline silver dressings. Part I: Chemical and biological properties
Biomaterials
(2005) - et al.
Antimicrobial intravascular catheters—which surface to coat?
J Hosp Infect
(1998)
Antibacterial effect of silver–zeolite on oral bacteria under anaerobic conditions
Dent Mater
Prolonged antimicrobial effect of tissue conditioners containing silver-zeolite
J Dent
A new and convenient route to polyacrylate/silver nanocomposites by light-induced cross-linking polymerization
Prog Org Coat
Silver nanoparticles as antimicrobial agent: a case study on E. coli as a model for Gram-negative bacteria
J Colloid Interface Sci
Antimicrobial effect of surgical masks coated with nanoparticles
J Hosp Infect
Experimental antimicrobial orthodontic adhesives using nanofillers and silver nanoparticles
Dent Mater
The antimicrobial efficacy of polyamide 6/silver-nano- and microcomposites
Mater Chem Phys
Efficacy of silver-coated medical devices
J Hosp Infect
Role of bacterial cell surface structures in Escherichia coli biofilm formation
Res Microbiol
What drives bacteria to produce a biofilm?
FEMS Microbiol Lett
Mechanisms of biofilm resistance to antimicrobial agents
Trends Microbiol
Silver and its application as an antimicrobial agent
Expert Opin Ther Pat
Antimicrobial silver/sodium carboxymethyl cotton dressings for burn wounds
Text Res J
Silver colloid nanoparticles: synthesis, characterization, and their antibacterial activity
J Phys Chem B
Prevention of catheter-related infections: the potential of a new nano-silver impregnated catheter
Int J Antimicrob Agents
Antibacterial activity of silver inorganic agent YDA filler
J Oral Rehabil
The preparation and characterization of silver-loading cellulose acetate hollow fiber membrane for water treatment
Polym Adv Technol
Antimicrobial activities of silver dressings: an in vitro comparison
J Med Microbiol
Silver nanoparticles and polymeric medical devices: a new approach to prevention of infection?
J Antimicrob Chemother
In vitro cytotoxicity of nanoparticles in mammalian germline stem cells
Toxicol Sci
Multimetal resistance and tolerance in microbial biofilms
Nat Rev Microbiol
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