Efficacy of an alcohol-based healthcare hand rub containing synergistic combination of farnesol and benzethonium chloride

Plant-based compositions for the treatment of local and topical bacterial infections: a patent review

Aim: To examine recent patents related to plants with antimicrobial effects. Methods: Our investigation was carried out using the Espacenet database, searching patents related to International Patent Classification (IPC) codes A61P31/04, and A61K36/00 between 2008 and 2023. Results: The study began with 360 patents, of which 15 were found to be duplicates; 144 were not related to the research topic and six were not available. Then, 48 patents were related to other administration routes. The final selection was 47 patents related to local administration compositions. The potential for these herbal compositions to be marketed as over-the-counter medicines was evident. Conclusion: Developing new plant-origin anti-infective agents could provide promising solutions for combating resistant infections and offer accessible treatment options.

Antibacterial Effects of Essential Oils of Seven Medicinal-Aromatic Plants Against the Fish Pathogen Aeromonas veronii bv. sobria: To Blend or Not to Blend?

Despite progress achieved, there is limited available information about the antibacterial activity of constituents of essential oils (EOs) from different medicinal-aromatic plants (MAPs) against fish pathogens and the complex interactions of blended EOs thereof. The present study aimed to investigate possible synergistic antimicrobial effects of EOs from seven Greek MAPs with strong potential against Aeromonas veronii bv. sobria, a fish pathogen associated with aquaculture disease outbreaks. The main objective was to evaluate whether blending of these EOs can lead to increased antimicrobial activity against the specific microorganism. A total of 127 combinations of EOs were prepared and their effect on A. veronii bv. sobria growth was tested in vitro. We examined both the inhibitory and bactericidal activities of the individual EOs and compared them to those of the blended EOs. The vast majority of the investigated combinations exhibited significant synergistic and additive effects, while antagonistic effects were evident only in a few cases, such as the mixtures containing EOs from rosemary, lemon balm and pennyroyal. The combination of EOs from Greek oregano and wild carrot, as well as the combinations of those two with Spanish oregano or savoury were the most promising ones. Overall, Greek oregano, savoury and Spanish oregano EOs were the most effective ones when applied either in pure form or blended with other EOs.

Farnesol: An approach on biofilms and nanotechnology

Biofilms are important virulence factor in infections caused by microorganisms because of its complex structure, which provide resistance to conventional antimicrobials. Strategies involving the use of molecules capable of inhibiting their formation and also act synergistically with conventional drugs have been explored. Farnesol is a molecule present in essential oils and produced by Candida albicans as a quorum sensing component. This sesquiterpene presents inhibitory properties in the formation of microbial biofilms and synergism with antimicrobials used in clinical practice, and can be exploited even for eradication of biofilms formed by drug-resistant microorganisms. Despite this, farnesol has physical and chemical characteristics that can limit its use, such as high hydrophobicity and volatility. Therefore, nanotechnology may represent an option to improve the efficiency of this molecule in high complex environments such as biofilms. Nanostructured systems present important results in the improvement of treatment with different commercial drugs and molecules with therapeutic or preventive potential. The formation of nanoparticles offers advantages such as protection of the incorporated drugs against degradation, improved biodistribution and residence time in specific treatment sites. The combination of farnesol with nanotechnology may be promising for the development of more effective antibiofilm therapies, as it can improve its solubility, reduce volatility, and increase bioavailability. This review summarizes existing data about farnesol, its action on biofilms, and discusses its encapsulation in nanostructured systems.

LAY SUMMARY

Farnesol is a natural compound that inhibits the formation of biofilms from different microbial species. The encapsulation of this molecule in nanoparticles is a promising alternative for the development of more effective therapies against biofilms.

An automated workflow to screen alkene reductases using high-throughput thin layer chromatography

BACKGROUND

Synthetic biology efforts often require high-throughput screening tools for enzyme engineering campaigns. While innovations in chromatographic and mass spectrometry-based techniques provide relevant structural information associated with enzyme activity, these approaches can require cost-intensive instrumentation and technical expertise not broadly available. Moreover, complex workflows and analysis time can significantly impact throughput. To this end, we develop an automated, 96-well screening platform based on thin layer chromatography (TLC) and use it to monitor in vitro activity of a geranylgeranyl reductase isolated from Sulfolobus acidocaldarius (SaGGR).

RESULTS

Unreduced SaGGR products are oxidized to their corresponding epoxide and applied to thin layer silica plates by acoustic printing. These derivatives are chromatographically separated based on the extent of epoxidation and are covalently ligated to a chromophore, allowing detection of enzyme variants with unique product distributions or enhanced reductase activity. Herein, we employ this workflow to examine farnesol reduction using a codon-saturation mutagenesis library at the Leu377 site of SaGGR. We show this TLC-based screen can distinguish between fourfold differences in enzyme activity for select mutants and validated those results by GC-MS.

CONCLUSIONS

With appropriate quantitation methods, this workflow can be used to screen polyprenyl reductase activity and can be readily adapted to analyze broader catalyst libraries whose products are amenable to TLC analysis.

Comparison of antimicrobial activities of natural essential oils and synthetic fragrances against selected environmental pathogens

Plant essential oils (EOs) are known to inhibit the growth of bacteria and fungi. Whether these antimicrobial effects are comparable to synthetic household products is less clear. Furthermore, limited research is available on the potential additive effect of blending EOs. In this investigation, a new EO blend containing orange, patchouli, peppermint, and clary sage was compared to its individual single oils and to three household products–air freshener, liquid soap, and body spray–for their ability to inhibit the growth of Staphylococcus aureus, Streptococcus pneumoniae, Pseudonomas aeruginosa, and Aspergillus brasiliensis in the disc-diffusion assay. The new EO blend significantly inhibited the growth of the four microorganisms. The zones of inhibition of new EO blend were greater than the air freshener and similar to the liquid soap and body spray, with the exception of Str. pneumoniae in which the body spray provided greater inhibitory zone. The new EO blend and the single oils, with the exception of peppermint, equally inhibited the growth of S. aureus and Str. pneumoniae suggesting no additive effect. P. aeruginosa and A. brasiliensis showed variable susceptibility to all EOs except for no susceptibility to orange and limonene. No difference was found between (−) and (+)-limonene; whereas, (+)-menthol showed greater effect than (−)-menthol. In conclusion, blending the EO of orange, patchouli, peppermint, and clary sage was beneficial in inhibiting the growth of S. aureus, Str. pneumoniae, P. aeruginosa, and A. brasiliensis providing a natural antimicrobial fragrance option over synthetics fragrances used in soaps, body sprays, and air fresheners.

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A new essential oil blend inhibited the growth of four common environmental pathogens.

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The antimicrobial activity of a natural essential oil blend was similar or better to three synthetic products.

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Peppermint essential oil was the main ingredient in the essential oil blend that provided the antimicrobial activity.

Multiple adaptive routes of Salmonella enterica Typhimurium to biocide and antibiotic exposure

Background

Biocides and antibiotics are used to eradicate or prevent the growth of microbial species on surfaces (occasionally on catheters), or infected sites, either in combination or sequentially, raising concerns about the development of co-resistance to both antimicrobial types. The effect of such compounds on Salmonella enterica, a major food-borne and zoonotic pathogen, has been analysed in different studies, but only few works evaluated its biological cost, and the overall effects at the genomic and transcriptomic levels associated with diverse phenotypes resulting from biocide exposure, which was the aim of this work.

Results

Exposure to triclosan, clorhexidine, benzalkonium, (but not to hypochlorite) resulted in mutants with different phenotypes to a wide range of antimicrobials even unrelated to the selective agent. Most biocide-resistant mutants showed increased susceptibility to compounds acting on the cell wall (β-lactams) or the cell membranes (poly-L-lysine, polymyxin B, colistin or toxic anions). Mutations (SNPs) were found in three intergenic regions and nine genes, which have a role in energy production, amino acids, carbohydrates or lipids metabolism, some of them involved in membrane transport and pathogenicity. Comparative transcriptomics of biocide-resistant mutants showed over-expression of genes encoding efflux pumps (sugE), ribosomal and transcription-related proteins, cold-shock response (cpeE) and enzymes of microaerobic metabolism including those of the phosphotransferase system. Mainly ribosomal, metabolic and pathogenicity-related genes had affected expression in both in vitro-selected biocide mutants and field Salmonella isolates with reduced biocide susceptibility.

Conclusions

Multiple pathways can be involved in the adaptation of Salmonella to biocides, mainly related with global stress, or involving metabolic and membrane alterations, and eventually causing “collateral sensitivity” to other antimicrobials. These changes might impact the bacterial-environment interaction, imposing significant bacterial fitness costs which may reduce the chances of fixation and spread of biocide resistant mutants.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-016-2778-z) contains supplementary material, which is available to authorized users.

Efficacy of Instant Hand Sanitizers against Foodborne Pathogens Compared with Hand Washing with Soap and Water in Food Preparation Settings: A Systematic Review

Hands can be a vector for transmitting pathogenic microorganisms to foodstuffs and drinks, and to the mouths of susceptible hosts. Hand washing is the primary barrier to prevent transmission of enteric pathogens via cross-contamination from infected persons. Conventional hand washing involves the use of water, soap, and friction to remove dirt and microorganisms. The availability of hand sanitizing products for use when water and soap are unavailable has increased in recent years. The aim of this systematic review was to collate scientific information on the efficacy of hand sanitizers compared with washing hands with soap and water for the removal of foodborne pathogens from the hands of food handlers. An extensive literature search was carried out using three electronic databases: Web of Science, Scopus, and PubMed. Twenty-eight scientific publications were ultimately included in the review. Analysis of this literature revealed various limitations in the scientific information owing to the absence of a standardized protocol for evaluating the efficacy of hand products and variation in experimental conditions. However, despite conflicting results, scientific evidence seems to support the historical skepticism about the use of waterless hand sanitizers in food preparation settings. Water and soap appear to be more effective than waterless products for removal of soil and microorganisms from hands. Alcohol-based products achieve rapid and effective inactivation of various bacteria, but their efficacy is generally lower against nonenveloped viruses. The presence of food debris significantly affects the microbial inactivation rate of hand sanitizers.

Rapid Antibacterial Activity of 2 Novel Hand Soaps: Evaluation of the Risk of Development of Bacterial Resistance to the Antibacterial Agents

Objective.

To evaluate the antimicrobial efficacy of and risk of organisms developing resistance to 2 novel hand soaps: (1) a soap containing triclosan, polyhexamethylene biguanide, and benzethonium chloride added to a soap base (TPB soap); and (2) a soap containing farnesol, polyhexamethylene biguanide, and benzethonium chloride added to a soap base (FPB soap). Tests also included soaps containing only triclosan.

Design.

The risk of emergence of resistant bacterial mutants was investigated by determining the susceptibility changes after repeated exposure of bacteria to the drugs and soaps in vitro. The effectiveness of the soaps was evaluated using an in vitro tube dilution method, a volunteer method (the ASTM standard), and 2 pig skin methods.

Results.

The minimum inhibitory concentration and minimum bactericidal concentration of triclosan against Staphylococcus, aureus increased 8- to 62.5-fold, whereas those of TPB and FPB (both alone and in soap) were unchanged. In vitro, TPB and FPB soaps produced higher log10 reductions in colony-forming units of all tested organisms (4.95-8.58) than did soaps containing triclosan alone (0.29-4.86). In the test using the pig skin and volunteer methods, TPB soap produced a higher log10 reduction in colony-forming units (3.1-3.3) than did the soap containing triclosan alone (2.6-2.8).

Conclusion.

The results indicate that TPB and FPB soaps may provide superior rapid and broad-spectrum efficacy with a lower risk of organisms developing resistance than do soaps containing triclosan alone. Pig skin methods may be used to predict the efficacy of antibacterial soaps in the rapid disinfection of contaminated hands. Hand washing with TPB and FPB soaps by healthcare workers and the general population may reduce the transmission of pathogens, with a lower risk of promoting the emergence of resistant organisms.

Assessing the contributions of the LiaS histidine kinase to the innate resistance of Listeria monocytogenes to nisin, cephalosporins, and disinfectants

The Listeria monocytogenes LiaSR two-component system (2CS) encoded by lmo1021 and lmo1022 plays an important role in resistance to the food preservative nisin. A nonpolar deletion in the histidine kinase-encoding component (ΔliaS) resulted in a 4-fold increase in nisin resistance. In contrast, the ΔliaS strain exhibited increased sensitivity to a number of cephalosporin antibiotics (and was also altered with respect to its response to a variety of other antimicrobials, including the active agents of a number of disinfectants). This pattern of increased nisin resistance and reduced cephalosporin resistance in L. monocytogenes has previously been associated with mutation of a second histidine kinase, LisK, which is a predicted regulator of liaS and a penicillin binding protein encoded by lmo2229. We noted that lmo2229 transcription is increased in the ΔliaS mutant and in a ΔliaS ΔlisK double mutant and that disruption of lmo2229 in the ΔliaS ΔlisK mutant resulted in a dramatic sensitization to nisin but had a relatively minor impact on cephalosporin resistance. We anticipate that further efforts to unravel the complex mechanisms by which LiaSR impacts on the antimicrobial resistance of L. monocytogenes could facilitate the development of strategies to increase the susceptibility of the pathogen to these agents.