Search

In the 1940s and 1950s, researchers seeking safe and novel ways to eliminate airborne pathogens from enclosed spaces, investigated glycol vapours as a method of disinfection. More recently, the COVID-19 pandemic highlighted the need for a non-toxic aerial disinfectant that can be used in the presence of people. This scoping review is intended to analyse the early and more recent literature on glycol disinfection, scrutinizing the methodologies used, and to determine if the use of glycols as modern-day disinfectants is justified PRISMA-ScR guidelines were used to assess the 749 articles retrieved from the Web of Science platform, with 46 articles retained after the search strategy was applied. Early studies generally demonstrated good disinfection capabilities against airborne bacteria and viruses, particularly with propylene glycol (PG) vapour. Vapour pressure, relative humidity, and glycol concentration were found to be important factors affecting the efficacy of glycol vapours. Contact times depended mainly on the glycol application method (i.e. aerosolization or liquid formulation), although information on how glycol efficacy is impacted by contact time is limited. Triethylene glycol (TEG) is deemed to have low toxicity, carcinogenicity, and mutagenicity and is registered for use in air sanitization and deodorization by the US Environmental Protection Agency. Glycols are also used in liquid formulations for their antimicrobial activity against a wide range of microorganisms, although when used as a non-active excipient in products, their contribution to antimicrobial efficacy is rarely assessed. The appropriate use of liquid glycol-containing formulations was found to positively impact the antimicrobial capabilities of disinfectants when used at temperatures <0, food preservatives, and dental medicaments. Providing modern delivery technology can accurately control environmental conditions, the use of aerosolized glycol formulations should lead to successful disinfection, aiding infection prevention, and control regimens., (© The Author(s) 2024. Published by Oxford University Press on behalf of Applied Microbiology International.)

This review examined 3655 articles on benzalkonium chloride (BKC), benzethonium chloride (BZT) and chloroxylenol (CHO) aiming to understand their impact on antimicrobial resistance. Following the application of inclusion/exclusion criteria, only 230 articles were retained for analysis; 212 concerned BKC, with only 18 for CHO and BZT. Seventy-eight percent of studies used MIC to measure BKC efficacy. Very few studies defined the term 'resistance' and 85% of studies defined 'resistance' as <10-fold increase (40% as low as 2-fold) in MIC. Only a few in vitro studies reported on formulated products and when they did, products performed better. In vitro studies looking at the impact of BKC exposure on bacterial resistance used either a stepwise training protocol or exposure to constant BKC concentrations. In these, BKC exposure resulted in elevated MIC or/and MBC, often associated with efflux, and at time, a change in antibiotic susceptibility profile. The clinical relevance of these findings was, however, neither reported nor addressed. Of note, several studies reported that bacterial strains with an elevated MIC or MBC remained susceptible to the in-use BKC concentration. BKC exposure was shown to reduce bacterial diversity in complex microbial microcosms, although the clinical significance of such a change has not been established. The impact of BKC exposure on the dissemination of resistant genes (notably efflux) remains speculative, although it manifests that clinical, veterinary and food isolates with elevated BKC MIC carried multiple efflux pump genes. The correlation between BKC usage and gene carriage, maintenance and dissemination has also not been established. The lack of clinical interpretation and significance in these studies does not allow to establish with certainty the role of BKC on AMR in practice. The limited literature and BZT and CHO do not allow to conclude that these will impact negatively on emerging bacterial resistance in practice., (© 2022 The Author. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.)

Aims: Dry surface biofilms (DSB) survive on environmental surfaces throughout hospitals, able to resist cleaning and disinfection interventions. This study aimed to produce a dual species DSB and explore the ability of commercially available wipe products to eliminate pathogens within a dual species DSB and prevent their transfer., Methods and Results: Staphylococcus aureus was grown with two different species of Bacillus on stainless steel discs, over 12 days using sequential hydration and dehydration phases. A modified version of ASTM 2967-15 was used to test six wipe products including one water control with the Fitaflex Wiperator. Staphylococcus aureus growth was inhibited when combined with Bacillus subtilis. Recovery of S. aureus on agar from a dual DSB was not always consistent. Our results did not provide evidence that Bacillus licheniformis protected S. aureus from wipe action. There was no significant difference of S. aureus elimination by antimicrobial wipes between single and dual species DSB. B. licheniformis was easily transferred by the wipe itself and to new surfaces both in a single and dual species DSB, whilst several wipe products inhibited the transfer of S. aureus from wipe. However, S. aureus direct transfer to new surfaces was not inhibited post-wiping., Conclusions: Although we observed that the dual DSB did not confer protection of S. aureus, we demonstrated that environmental species can persist on surfaces after disinfection treatment. Industries should test DSB against future products and hospitals should consider carefully the products they choose., Significance and Impact of the Study: To our knowledge, this is the first study reporting on the production of a dual species DSB. Multispecies DSB have been identified throughout the world on hospital surfaces, but many studies focus on single species biofilms. This study has shown that DSB behave differently to hydrated biofilms., (© 2022 The Authors. Journal of Applied Microbiology published by John Wiley & Sons Ltd on behalf of Society for Applied Microbiology.)

Long before the nature of infection was recognized, or the significance of biofilms in delayed healing was understood, antimicrobial agents were being used in wound care. In the last 70 years, antibiotics have provided an effective means to control wound infection, but the continued emergence of antibiotic-resistant strains and the documented antibiotic tolerance of biofilms has reduced their effectiveness. A range of wound dressings containing an antimicrobial (antibiotic or non-antibiotic compound) has been developed. Whereas standardized methods for determining the efficacy of non-antibiotic antimicrobials in bacterial suspension tests were developed in the early twentieth century, standardized ways of evaluating the efficacy of antimicrobial dressings against microbial suspensions and biofilms are not available. Resistance to non-antibiotic antimicrobials and cross-resistance with antibiotics has been reported, but consensus on breakpoints is absent and surveillance is impossible. Antimicrobial stewardship is therefore in jeopardy. This review highlights these difficulties and in particular the efficacy of current non-antibiotic antimicrobials used in dressings, their efficacy, and the challenges of translating in vitro efficacy data to the efficacy of dressings in patients. This review calls for a unified approach to developing standardized methods of evaluating antimicrobial dressings that will provide an improved basis for practitioners to make informed choices in wound care., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy.)

Emerging studies increasingly demonstrate the importance of the throat and salivary glands as sites of virus replication and transmission in early COVID-19 disease. SARS-CoV-2 is an enveloped virus, characterized by an outer lipid membrane derived from the host cell from which it buds. While it is highly sensitive to agents that disrupt lipid biomembranes, there has been no discussion about the potential role of oral rinsing in preventing transmission. Here, we review known mechanisms of viral lipid membrane disruption by widely available dental mouthwash components that include ethanol, chlorhexidine, cetylpyridinium chloride, hydrogen peroxide, and povidone-iodine. We also assess existing formulations for their potential ability to disrupt the SARS-CoV-2 lipid envelope, based on their concentrations of these agents, and conclude that several deserve clinical evaluation. We highlight that already published research on other enveloped viruses, including coronaviruses, directly supports the idea that oral rinsing should be considered as a potential way to reduce transmission of SARS-CoV-2. Research to test this could include evaluating existing or specifically tailored new formulations in well-designed viral inactivation assays, then in clinical trials. Population-based interventions could be undertaken with available mouthwashes, with active monitoring of outcome to determine efficacy. This is an under-researched area of major clinical need., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Physiological Society.)

Objectives: To elucidate the mechanisms of spore resistance to and killing by the oxidizing microbicide peracetic acid (PAA)., Methods: Mutants of Bacillus subtilis lacking specific spore structures were used to identify resistance properties in spores and to understand the mechanism of action of PAA. We also assessed the effect of PAA treatment on a number of spore properties including heat tolerance, membrane integrity and germination., Results: The spore coat is essential for spore PAA resistance as spores with defective coats were greatly sensitized to PAA treatment. Small acid-soluble spore proteins apparently provide no protection against PAA. Defects in spore germination, specifically in germination via the GerB and GerK but not the GerA germination receptors, as well as leakage of internal components suggest that PAA is active at the spore inner membrane. It is therefore likely that the inner membrane is the major site of PAA's sporicidal activity., Conclusions: PAA treatment targets the spore membrane, with some of its activity directed specifically against the GerB and GerK germination receptors., (© The Author 2014. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Hydrogen peroxide is extensively used as a biocide, particularly in applications where its decomposition into non-toxic by-products is important. Although increasing information on the biocidal efficacy of hydrogen peroxide is available, there is still little understanding of its biocidal mechanisms of action. This review aims to combine past and novel evidence of interactions between hydrogen peroxide and the microbial cell and its components, while reflecting on alternative applications that make use of gaseous hydrogen peroxide. It is currently believed that the Fenton reaction leading to the production of free hydroxyl radicals is the basis of hydrogen peroxide action and evidence exists for this reaction leading to oxidation of DNA, proteins and membrane lipids in vivo. Investigations of DNA oxidation suggest that the oxidizing radical is the ferryl radical formed from DNA-associated iron, not hydroxyl. Investigations of protein oxidation suggest that selective oxidation of certain proteins might occur, and that vapour-phase hydrogen peroxide is a more potent oxidizer of protein than liquid-phase hydrogen peroxide. Few studies have investigated membrane damage by hydrogen peroxide, though it is suggested that this is important for the biocidal mechanism. No studies have investigated damage to microbial cell components under conditions commonly used for sterilization. Despite extensive studies of hydrogen peroxide toxicity, the mechanism of its action as a biocide requires further investigation.

Objectives: The aim of this study was to assess the risk associated with microbial contamination in the hub-fluid in Luer-lock syringes to the end-product, and ultimately patients., Method: The hub-fluid of 48 sterile syringes prefilled with broth was contaminated with a low number of Staphylococcus epidermidis or spores of Bacillus subtilis. After incubation for three weeks, the syringe fills were tested for the presence of bacterial contaminants and some syringes were used to inoculate an end product broth that was then investigated for the presence of microorganisms., Key Findings: After three weeks of incubation only 20.8% of syringe fills showed turbidity, although following further investigation 70.8% were positive for the presence of viable bacteria, whereas 95.6% of end products became contaminated following injection of the syringe fill., Conclusions: These findings add quantitative data that support the current practice of discarding syringes with residue around the cap., (© 2010 The Authors. JPP © 2010 Royal Pharmaceutical Society.)

Objectives: Antimicrobials such as chlorine dioxide, peracetic acid and hydrogen peroxide (H(2)O(2)) share a basic mechanism of action (chemical oxidation of cellular components), but profound differences arise in their efficacy against microorganisms. Optimization of activity requires an understanding of their interaction with microbial targets and a clear differentiation between the chemical efficacies of each oxidative biocide. This study aimed to elucidate the biochemical mechanisms of action of oxidizing biocides at a macromolecular level, using amino acids, protein and an enzyme as model substrates for the action of each biocide., Methods: The interactions of a number of oxidising agents (liquid and gaseous H(2)O(2), ClO(2), peracetic acid formulations) with amino acids, proteins (bovine serum albumin and aldolase) and enzymes were investigated by spectrophotometry, SDS-PAGE and alkaline phosphatase activity measurements., Results: Biocide reactions yielded different types of oxidative structural change and different degrees of oxidation to amino acids and proteins, and differences in activity against a microbial enzyme. In particular there was a marked difference in the interactions of liquid H(2)O(2) and gaseous H(2)O(2) with the macromolecules, the latter causing greater oxidation; these results explain the dramatic differences in antimicrobial efficacy between liquid and gas peroxide., Conclusions: These results provide a comprehensive understanding of the differences in interactions between a number of oxidizing agents and macromolecules commonly found in microbial cells. Biochemical mechanistic differences between these oxidative biocides do exist and lead to differential effects on macromolecules. This in turn could provide an explanation as to their differences in biocidal activity, particularly between liquid and gas peroxide.

An increasing number of microorganisms, including bacteria but also viruses and eukaryotes, have been described as benefiting from interaction with free-living amoebae (FLA). Beneficial interaction can be due to resistance to predation conferring ecological advantage, intracellular survival and/or intracellular proliferation. This review highlights the potential risk associated with amoebae by listing all known pathogenic microbial species for which growth and/or survival promotion by FLA (mainly Acanthamoeba spp.) has been demonstrated. It focuses on the susceptibility of amoebal and intra-amoebal bacteria to various categories of biocides, the known mechanisms of action of these biocides against trophozoites and cysts and the various methods used to demonstrate efficacy of treatments against FLA. Brief descriptions of FLA ecology and prevalence in domestic/institutional water systems and their intrinsic pathogenicity are also presented. The intention is to provide an informed opinion on the environmental risks associated with the presence of FLA and on the survival of cysts following biocidal treatments, while also highlighting the need to conduct research on the roles of amoebae in aquatic ecosystems., (© 2009 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.)

Aims: To assess the potential bactericidal activity of amine oxide (C10-C16-alkyldimethyl N-oxides) against Streptococcus mutans grown as planktonic suspension and as biofilm on hydroxyapatite discs, and its ability to control acidification of the media., Methods: Amine oxide bacteriostasis was investigated using the Bioscreen C Microbiological Growth Analyser, while a standard suspension test was used to determine its bactericidal efficacy. In addition, the lethal activity of amine oxide was studied against sedimentation biofilms of S. mutans on hydroxyapatite (HA) discs and resuspended biofilms. Several parameters were considered such as the surfactant concentration, pH, the starting inoculum and the maturity of the biofilm., Results: Amine oxide was bacteriostatic against planktonic S. mutans at a low concentration (0.006% v/v) and highly bactericidal against S. mutans in suspension or in a mature biofilm on hydroxyapatite, although the concentration required to achieve the latter effect was four times higher. The activity of amine oxide against biofilms depended upon its concentration and the age of the biofilm. In addition, amine oxide pre-treatment of the HA discs did not affect the growth of the biofilm. Finally, amine oxide did not prevent the acidification of the medium, although lower pHs had a potentiating effect on amine oxide activity., Conclusion: Amine oxide showed high potential for controlling early biofilms caused by periodontal bacteria. Further investigations should be carried out, particularly on the potential toxicity of amine oxide and its efficacy in complex formulations for oral care products.

Objectives: Polyquaternium-1 (PQ-1) is a biocide used commercially in a contact lens disinfecting solution, 'Opti-Free Express (Alcon) Multi-Purpose Disinfecting Solution'. The genetic basis for resistance of Serratia marcescens to PQ-1 was investigated using a random transposon-based mutagenesis approach., Methods: S. marcescens was subjected to random transposon mutagenesis using a mini-Tn5 Km2 transposon. Mutants with increased susceptibility to PQ-1 were selected and the disrupted genes were identified. Antibiotic susceptibility profiles were also determined for all of the mutants., Results: A wide range of genes were found to be disrupted in the mutants. The most common were genes associated with the cell membranes, or involved in biosynthesis and metabolism., Conclusions: This study shows that random transposon mutagenesis is an effective tool for the elucidation of mechanisms of action and resistance to biocides. The results support our previous findings that PQ-1 is active against the cytoplasmic membrane of S. marcescens.

Objectives: Polyquad (Alcon) (polyquaternium-1, PQ-1) and Aldox (Alcon) (myristamidopropyl dimethylamine, MAPD) are two biocides that are used commercially in a contact lens disinfecting solution, namely Opti-Free Express (Alcon) multi-purpose disinfecting solution. Their potential 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.