A. Denver Russell

Bio: A. Denver Russell is an academic researcher from Cardiff University. The author has contributed to research in topics: Contact lens & Antimicrobial. The author has an hindex of 7, co-authored 9 publications receiving 4022 citations.

Antiseptics and Disinfectants: Activity, Action, and Resistance

Abstract: Antiseptics and disinfectants are extensively used in hospitals and other health care settings for a variety of topical and hard-surface applications A wide variety of active chemical agents (biocides) are found in these products, many of which have been used for hundreds of years, including alcohols, phenols, iodine, and chlorine Most of these active agents demonstrate broad-spectrum antimicrobial activity; however, little is known about the mode of action of these agents in comparison to antibiotics This review considers what is known about the mode of action and spectrum of activity of antiseptics and disinfectants The widespread use of these products has prompted some speculation on the development of microbial resistance, in particular whether antibiotic resistance is induced by antiseptics or disinfectants Known mechanisms of microbial resistance (both intrinsic and acquired) to biocides are reviewed, with emphasis on the clinical implications of these reports

Aspects of the antimicrobial mechanisms of action of a polyquaternium and an amidoamine

Abstract: Objectives: Polyquad (Alcon) (polyquaternium-1, PQ-1) and Aldox (Alcon) (myristamidopropyl dimethylamine, MAPD) are two biocides that are used commercially in a contact lens disinfect- ing solution, namely Opti-Free Express (Alcon) multi-purpose disinfecting solution. Their poten- tial mechanisms of action were investigated against a range of common ocular pathogens. These were Acanthamoeba castellanii (trophozoites and cysts), Aspergillus fumigatus, Candida albicans, Pseudomonas aeruginosa, Serratia marcescens and Staphylococcus aureus. Methods: Three aspects were investigated: the lethal effects of the biocides on the organisms, the leakage of K + from treated cells, and the lysis of spheroplasts derived from the cells. Results: PQ-1 was found to have predominantly antibacterial activity, and induced K + leakage from the bacteria and C. albicans. It also caused lysis of spheroplasts of S. marcescens, but not those of C. albicans. MAPD was active against all of the organisms, but showed higher activity against the fungi and amoeba. It induced K + leakage from A. fumigatus and C. albicans, and like PQ-1, lysed the spheroplasts of S. marcescens but not C. albicans. Conclusions: The two biocides have different spectra of antimicrobial activity. PQ-1 has mainly antibacterial activity, whereas MAPD was active against all of the test organisms, particularly the fungi.

Performance of contact lens disinfecting solutions against Pseudomonas aeruginosa in the presence of organic load.

Abstract: Purpose.Contact lens wearers can become noncompliant with lens disinfection procedures. The purpose of this study was to evaluate multipurpose contact lens disinfecting solutions in the presence of organic soil.Methods.OPTI-FREE EXPRESS and three products preserved with polyhexamethylene biguanide (

Does the antibacterial activity of silver nanoparticles depend on the shape of the nanoparticle? A study of the Gram-negative bacterium Escherichia coli.

Abstract: In this work we investigated the antibacterial properties of differently shaped silver nanoparticles against the gram-negative bacterium Escherichia coli, both in liquid systems and on agar plates. Energy-filtering transmission electron microscopy images revealed considerable changes in the cell membranes upon treatment, resulting in cell death. Truncated triangular silver nanoplates with a {111} lattice plane as the basal plane displayed the strongest biocidal action, compared with spherical and rod-shaped nanoparticles and with Ag+ (in the form of AgNO3). It is proposed that nanoscale size and the presence of a {111} plane combine to promote this biocidal property. To our knowledge, this is the first comparative study on the bactericidal properties of silver nanoparticles of different shapes, and our results demonstrate that silver nanoparticles undergo a shape-dependent interaction with the gram-negative organism E. coli.

Antifouling coatings: recent developments in the design of surfaces that prevent fouling by proteins, bacteria, and marine organisms.

Abstract: The major strategies for designing surfaces that prevent fouling due to proteins, bacteria, and marine organisms are reviewed. Biofouling is of great concern in numerous applications ranging from biosensors to biomedical implants and devices, and from food packaging to industrial and marine equipment. The two major approaches to combat surface fouling are based on either preventing biofoulants from attaching or degrading them. One of the key strategies for imparting adhesion resistance involves the functionalization of surfaces with poly(ethylene glycol) (PEG) or oligo(ethylene glycol). Several alternatives to PEG-based coatings have also been designed over the past decade. While protein-resistant coatings may also resist bacterial attachment and subsequent biofilm formation, in order to overcome the fouling-mediated risk of bacterial infection it is highly desirable to design coatings that are bactericidal. Traditional techniques involve the design of coatings that release biocidal agents, including antibiotics, quaternary ammonium salts (QAS), and silver, into the surrounding aqueous environment. However, the emergence of antibiotic- and silver-resistant pathogenic strains has necessitated the development of alternative strategies. Therefore, other techniques based on the use of polycations, enzymes, nanomaterials, and photoactive agents are being investigated. With regard to marine antifouling coatings, restrictions on the use of biocide-releasing coatings have made the generation of nontoxic antifouling surfaces more important. While considerable progress has been made in the design of antifouling coatings, ongoing research in this area should result in the development of even better antifouling materials in the future.

Resistance of Bacillus endospores to extreme terrestrial and extraterrestrial environments.

Abstract: Endospores of Bacillus spp., especially Bacillus subtilis, have served as experimental models for exploring the molecular mechanisms underlying the incredible longevity of spores and their resistance to environmental insults. In this review we summarize the molecular laboratory model of spore resistance mechanisms and attempt to use the model as a basis for exploration of the resistance of spores to environmental extremes both on Earth and during postulated interplanetary transfer through space as a result of natural impact processes.

Antibacterial Activity and Mechanism of Action of the Silver Ion in Staphylococcus aureus and Escherichia coli

Abstract: The antibacterial effect and mechanism of action of a silver ion solution that was electrically generated were investigated for Staphylococcus aureus and Escherichia coli by analyzing the growth, morphology, and ultrastructure of the bacterial cells following treatment with the silver ion solution. Bacteria were exposed to the silver ion solution for various lengths of time, and the antibacterial effect of the solution was tested using the conventional plate count method and flow cytometric (FC) analysis. Reductions of more than 5 log10 CFU/ml of both S. aureus and E. coli bacteria were confirmed after 90 min of treatment with the silver ion solution. Significant reduction of S. aureus and E. coli cells was also observed by FC analysis; however, the reduction rate determined by FC analysis was less than that determined by the conventional plate count method. These differences may be attributed to the presence of bacteria in an active but nonculturable (ABNC) state after treatment with the silver ion solution. Transmission electron microscopy showed considerable changes in the bacterial cell membranes upon silver ion treatment, which might be the cause or consequence of cell death. In conclusion, the results of the present study suggest that silver ions may cause S. aureus and E. coli bacteria to reach an ABNC state and eventually die.