Combination of Miconazole and Domiphen Bromide Is Fungicidal against Biofilms of Resistant Candida spp

The combination of allicin with domiphen is effective against microbial biofilm formation

Background

Microorganisms in biofilms are particularly difficult to control because of their increased survival and antibiotic resistance. Allicin and domiphen were employed to inhibit the microbial growth and biofilm formation of Staphylococcus aureus, Escherichia coli, and Candida albicans strains.

Methods

Broth microdilution method and checkerboard assay were conducted to determine the efficacy of allicin combined with domiphen against S. aureus, E. coli, and C. albicans. Microbial biofilm formation was measured using the crystal violet staining method and fluorescence microscopy. And the total viable count of the biofilm cells on material surface after the treatment with antimicrobial reagents was calculated with the plate count technique.

Results

The two drugs showed synergistic effects against the pathogens with a fractional bactericidal concentration of less than 0.38. The combination of 64 μg/mL allicin with 1 μg/mL domiphen dispersed over 50% of the biofilm mass of S. aureus, E. coli, and C. albicans. In addition, the drug combination reduced the total viable counts of E. coli and C. albicans biofilm cells on stainless steel and polyethylene surfaces by more than 102 CFU/mL.

Conclusion

The combination of allicin and domiphen is an effective strategy for efficiently decreasing biofilms formation on various industrial materials surfaces.

Efficacy of a mouthwash containing ε-poly-L-lysine, funme peptides and domiphen in reducing halitosis and supragingival plaque: a randomized clinical trial

OBJECTIVE

To evaluate the antibacterial effectiveness of a combination of ε-poly-L-lysine (ε-PL), funme peptide (FP) as well as domiphen against oral pathogens, and assess the efficacy of a BOP® mouthwash supplemented with this combination in reducing halitosis and supragingival plaque in a clinical trial.

MATERIALS AND METHODS

The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the compound against Fusobacterium nucleatum, Porphyromonas gingivalis, Streptococcus mutans, and Aggregatibacter actinomycetemcomitans were determined by the gradient dilution method. Subsequently, the CCK-8 assay was used to detect the toxicity of mouthwash on human gingival fibroblastst, and the effectiveness in reducing halitosis and supragingival plaque of the mouthwash supplemented with the combination was analyzed by a randomized, double-blind, parallel-controlled clinical trial.

RESULTS

The combination exhibited significant inhibitory effects on tested oral pathogens with the MIC < 1.56% (v/v) and the MBC < 3.13% (v/v), and the mouthwash containing this combination did not inhibit the viability of human gingival fibroblasts at the test concentrations. The clinical trial showed that the test group displayed notably lower volatile sulfur compounds (VSCs) at 0, 10, 24 h, and 7 d post-mouthwash (P < 0.05), compared with the baseline. After 7 days, the VSC levels of the and control groups were reduced by 50.27% and 32.12%, respectively, and notably cutting severe halitosis by 57.03% in the test group. Additionally, the Plaque Index (PLI) of the test and control group decreased by 54.55% and 8.38%, respectively, and there was a significant difference in PLI between the two groups after 7 days (P < 0.01).

CONCLUSIONS

The combination of ε-PL, FP and domiphen demonstrated potent inhibitory and bactericidal effects against the tested oral pathogens, and the newly formulated mouthwash added with the combination exhibited anti-dental plaque and anti-halitosis properties in a clinical trial and was safe.

TRIAL REGISTRATION

The randomized controlled clinical trial was registered on Chinese Clinical Trial Registry (No. ChiCTR2300073816, Date: 21/07/2023).

Combining with domiphen bromide restores colistin efficacy against colistin-resistant Gram-negative bacteria in vitro and in vivo

Today, colistin is considered a last-resort antibiotic for treating multidrug-resistant (MDR) Gram-negative bacteria (GNB). However, the increased and improper use of colistin has led to the emergence of colistin-resistant (Col-R) GNB. Thus, it is urgent to develop new drugs and therapies in response to the ongoing emergence of colistin resistance. In this study, we investigated the antibacterial and antibiofilm activities of the quaternary ammonium compound domiphen bromide (DB) in combination with colistin against clinical Col-R GNB both in vitro and in vivo. Checkerboard assay and time-kill analysis demonstrated significant synergistic antibacterial effects of the colistin/DB combination. The synergistic antibiofilm activity was confirmed through crystal violet staining and scanning electron microscopy (SEM). Furthermore, the colistin/DB combination exhibited increased survival rates in infected larvae and reduced bacterial loads in a mouse thigh infection model. The cytotoxicity measurement and hemolysis test showed that the combination did not adversely affect cell viability at synergistic concentrations. The alkaline phosphatase (ALP) leak test and propidium iodide (PI) staining analysis further revealed that the colistin/DB combination enhanced the therapeutic effect of colistin by altering bacterial membrane permeability. The ROS assays revealed that the combination induced the accumulation of bacterial ROS, leading to bacterial death. In conclusion, our study is the first to identify DB as a colistin potentiator, effectively restoring the sensitivity of bacteria to colistin. It provides a promising alternative approach for combating Col-R GNB infections.

Transcriptomics-based investigation of molecular mechanisms underlying synergistic antimicrobial effects of AgNPs and Domiphen on the human fungal pathogen Aspergillus fumigatus

Critically ill patients have higher risk of serious fungal infections, such as invasive aspergillosis (IA) which is mainly caused by the human fungal pathogen Aspergillus fumigatus. Triazole drugs are the primary therapeutic agents for the first-line treatment of IA, which could easily cause drug resistance problems. Here, we assess the potential of AgNPs synthesized with Artemisia argyi leaf extract and domiphen as new antifungal agents to produce synergistic antimicrobial effects on Aspergillus fumigatus, and dissect possible molecular mechanisms of action. Plate inoculation assays combined with drug susceptibility test and cytotoxicity test showed that the combination of AgNPs and domiphen has synergistic antimicrobial effects on A. fumigatus with low cytotoxicity. Gene Ontology (GO) enrichment analysis showed that AgNPs and domiphen inhibit the growth of A. fumigatus by suppressing nitrate assimilation, and purine nucleobase metabolic process and amino acid transmembrane transport, respectively. When the two drugs are combined, AgNPs has epistatic effects on domiphen. Moreover, the combination of AgNPs and domiphen primarily influence secondary metabolites biosynthesis, steroid biosynthesis and nucleotide sugar metabolism of A. fumigatus via Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Furthermore, protein-protein interactions (PPI) analysis combined with validation experiments showed that the combination of AgNPs and domiphen could enhance the expression of copper transporter and inhibit nitrogen source metabolism. In addition, the synergistic antimicrobial effects could be enhanced or eliminated depending on exogenous addition of copper and nitrogen source, respectively. Taken together, the results of this study provide a theoretical basis and a new strategy for the treatment of IA.

OUP accepted manuscript

Candida auris is an emerging, multi drug resistant fungal pathogen that has caused infectious outbreaks in over 45 countries since its first isolation over a decade ago, leading to in-hospital crude mortality rates as high as 72%. The fungus is also acclimated to disinfection procedures and persists for weeks in nosocomial ecosystems. Alarmingly, the outbreaks of C. auris infections in Coronavirus Disease-2019 (COVID-19) patients have also been reported. The pathogenicity, drug resistance and global spread of C. auris have led to an urgent exploration of novel, candidate antifungal agents for C. auris therapeutics. This narrative review codifies the emerging data on the following new/emerging antifungal compounds and strategies: antimicrobial peptides, combinational therapy, immunotherapy, metals and nano particles, natural compounds, and repurposed drugs. Encouragingly, a vast majority of these exhibit excellent anti- C. auris properties, with promising drugs now in the pipeline in various stages of development. Nevertheless, further research on the modes of action, toxicity, and the dosage of the new formulations are warranted. Studies are needed with representation from all five C. auris clades, so as to produce data of grater relevance, and broader significance and validity.

Combination of AgNPs and Domiphen is Antimicrobial Against Biofilms of Common Pathogens

Purpose

The aim was to evaluate the antimicrobial potential of AgNPs synthesized with Artemisia argyi leaf extract and investigate the antimicrobial synergistic effects of AgNPs combined with domiphen and provide an efficient and broad-spectrum combination drug strategy.

Methods

AgNPs synthesized with Artemisia argyi leaf extract were studied using UV–vis spectroscopy, FTIR spectroscopy and particle size analysis. Then, Artemisia argyi leaf extract-synthesized AgNPs and domiphen were tested against Acinetobacter baumannii (ATCC 19606), Staphylococcus aureus (ATCC 6538), Escherichia coli (8099) and Candida albicans (ATCC 10231), respectively. Then, we explore synergistic antimicrobial effect and synergistic anti-biofilm effect through combined drug susceptibility test and combined drug minimum biofilm eradication concentration (MBEC₅₀) test.

Results

Characteristic absorption bands of AgNPs were found near 430 nm in the UV–vis spectrum. Particle size analysis results revealed that the average particle size of Artemisia argyi leaf extract-synthesized AgNPs was 77.6 nm. Artemisia argyi leaf extract-synthesized AgNPs showed high antimicrobial activity against the above four strains. Minimum inhibitory concentration (MIC) of Artemisia argyi leaf extract-synthesized AgNPs against strains was 1 μg/mL for Acinetobacter baumannii, 2 μg/mL for Staphylococcus aureus, Escherichia coli and Candida albicans. MBEC₅₀ of Artemisia argyi leaf extract-synthesized AgNPs against strains was 2 μg/mL for Acinetobacter baumannii, 4 μg/mL for Staphylococcus aureus, 1/2 μg/mL for Escherichia coli and 2 μg/mL for Candida albicans. The combination of Artemisia argyi leaf extract-synthesized AgNPs and domiphen has synergistic antimicrobial effect and synergistic anti-biofilm effect. Fractional inhibitory concentration (FIC) was ≤0.5.

Conclusion

Artemisia argyi leaf extract-synthesized AgNPs had antimicrobial activity against the above four strains. The combination of Artemisia argyi leaf extract-synthesized AgNPs and domiphen has synergistic antimicrobial effects to reduce the dosage of each antimicrobial drugs. Artemisia argyi leaf extract-synthesized AgNPs and domiphen have synergistic anti-biofilm effects.

Antifungal Activity of Linear and Disulfide-Cyclized Ultrashort Cationic Lipopeptides Alone and in Combination with Fluconazole against Vulvovaginal Candida spp

Vulvovaginal candidiasis (VVC) occurs in over 75% of women at least once during their lifetime and is an infection that significantly affects their health. Candida strains resistant to standard azole antifungal therapy and relapses of VVC are more and more common. Hypothetically, biofilm is one of the main reasons of relapses and failure of the therapy. Ultrashort cationic lipopeptides (USCLs) exhibit high antimicrobial activities. Our previous study on USCLs revealed that disulfide cyclization can result in selective antifungal compounds. Therefore, four USCL were selected and their antifungal activity were studied on 62 clinical strains isolated from VVC. The results confirmed previous premises that cyclic analogs have increased selectivity between fungal cells and keratinocytes and improved anticandidal activity compared to their linear analogs against both planktonic and biofilm cultures. On the other hand, linear lipopeptides in combination with fluconazole showed a synergistic effect. It was found that the minimum inhibitory concentrations of the tested compounds in combination with fluconazole were at least four times lower than when used separately. Our results indicate that combination therapy of VVC with USCLs and fluconazole at low non-toxic concentrations can be beneficial owing to the synergistic effect. However, further in vivo studies are needed to confirm this hypothesis.

Role of Antifungal Combinations in Difficult to Treat Candida Infections

Candida infections are varied and, depending on the immune status of the patient, a life-threatening form may develop. C. albicans is the most prevalent species isolated, however, a significant shift towards other Candida species has been noted. Monotherapy is frequently indicated, but the patient's evolution is not always favorable. Drug combinations are a suitable option in specific situations. The aim of this review is to address this problem and to discuss the role of drug combinations in difficult to treat Candida infections. A search for eligible studies in PubMed and Google Scholar databases was performed. An analysis of the data was carried out to define in which cases a combination therapy is the most appropriate. Combination therapy may be used for refractory candidiasis, endocarditis, meningitis, eye infections and osteomyelitis, among others. The role of the drug combination would be to increase efficacy, reduce toxicity and improve the prognosis of the patient in infections that are difficult to treat. More clinical studies and reporting of cases in which drug combinations are used are needed in order to have more data that support the use of this therapeutic strategy.

New weapons to fight a new enemy: A systematic review of drug combinations against the drug-resistant fungus Candida auris

Candida auris is an emerging and drug-resistant pathogen. Drug combination is a promising approach against such pathogens. This study was conducted to provide an overview of all the studied drug combinations against C. auris. Relevant articles reporting results of any drug/non-drug combinations against C. auris were found by a systematic search in PubMed, Scopus and Web of Science (ISI), and in Google Scholar up to 1 October 2020. From 187 articles retrieved in the primary search, 23 met the inclusion criteria. In total, 124 different combinations including antifungal with antifungal (45), antifungal with other antimicrobials (11), antifungal with non-antimicrobials (32), antifungal with natural compounds (25) and between natural compounds (11) have been reported. Complete or partial synergistic effects have been reported for 3 out of 45 (6.67%) combinations of two antifungal agents, 8 out of 11 (72.73%) combinations involving antifungal agents and antimicrobials, 15 out of 32 (46.88%) of combinations between antifungal agents with non-antimicrobials, 16 out of 25 (64%) of combinations involving antifungal agents and natural compounds, and 3 out of 11 (22.27%) of combinations involving multiple natural compounds. Antagonistic interactions have been reported for 1 out of 32 (3.13%) and 8 out of 25 (32%) of combinations between antifungal drugs with non-antimicrobials and with natural compounds, respectively. Different drugs/compounds could potentiate the activity of antifungal drugs using this approach. However, despite the availability of this promising initial data, many more studies will be required to elucidate whether favourable interactions observed in vitro might translate into tangible clinical benefits.

Combining Miconazole and Domiphen Bromide Results in Excess of Reactive Oxygen Species and Killing of Biofilm Cells

Fungal biofilm-related infections are increasingly occurring. We previously identified a fungicidal antibiofilm combination, consisting of miconazole (MCZ) and the quaternary ammonium compound domiphen bromide (DB). DB eliminates tolerance rather than altering the susceptibility to MCZ of various Candida spp. Here we studied the mode of action of the MCZ-DB combination in more detail. We found that DB's action increases the permeability of the plasma membrane as well as that of the vacuolar membrane of Candida spp. Furthermore, the addition of DB affects the intracellular azole distribution. MCZ is a fungicidal azole that, apart from its well-known inhibition of ergosterol biosynthesis, also induces accumulation of reactive oxygen species (ROS). Interestingly, the MCZ-DB combination induced significantly more ROS in C. albicans biofilms as compared to single compound treatment. Co-administration of the antioxidant ascorbic acid resulted in abolishment of the ROS generated by MCZ-DB combination as well as its fungicidal action. In conclusion, increased intracellular MCZ availability due to DB's action results in excess of ROS and enhanced fungal cell killing.

Combination Therapy to Treat Fungal Biofilm-Based Infections

An increasing number of people is affected by fungal biofilm-based infections, which are resistant to the majority of currently-used antifungal drugs. Such infections are often caused by species from the genera Candida, Aspergillus or Cryptococcus. Only a few antifungal drugs, including echinocandins and liposomal formulations of amphotericin B, are available to treat such biofilm-based fungal infections. This review discusses combination therapy as a novel antibiofilm strategy. More specifically, in vitro methods to discover new antibiofilm combinations will be discussed. Furthermore, an overview of the main modes of action of promising antibiofilm combination treatments will be provided as this knowledge may facilitate the optimization of existing antibiofilm combinations or the development of new ones with a similar mode of action.