Combination of Farnesol with Common Antifungal Drugs: Inhibitory Effect against Candida Species Isolated from Women with RVVC

Antifungal susceptibility testing and determination of local epidemiological cut-off values for Candida species isolated from women with vulvovaginal candidiasis

The lack of clinical breakpoints and epidemiological cut-off values (ECOFFs) for antifungals prescribed for vulvovaginal candidiasis (VVC) make interpretation of antifungal susceptibility data difficult. This leads to empirical prescribing, poor clinical management and emergence of resistance. The in vitro susceptibilities of 152 Candida albicans, 105 Candida parapsilosis, 31 Nakaseomyces glabratus, and 8 Pichia kudriavzevii VVC isolates against eight antifungals, were determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) E.Def 7.4. The minimum inhibitory concentration (MIC) distributions were analyzed and local ECOFFs were determined visually and statistically. The in vitro activity of azoles was correlated with fluconazole susceptibility and clinical data were evaluated. The MICs of various azoles showed a significant correlation with the MICs of fluconazole and fluconazole non-wild type (WT) isolates had significantly higher MICs for other azoles. The estimated local ECOFFs for C. albicans were 0.016 mg/L (ketoconazole, clotrimazole), 0.06 mg/L (miconazole, econazole, itraconazole), 1 mg/L (fenticonazole), and 3,200 mg/L (boric acid). For C. parapsilosis, local ECOFFs were 0.06 mg/L (ketoconazole, clotrimazole, itraconazole), 1 mg/L (miconazole, econazole), 2 mg/L (fenticonazole), and 3,200 mg/L (boric acid). For N. glabratus, they were 1 mg/L (ketoconazole, clotrimazole, miconazole, itraconazole), 2 mg/L (econazole, fenticonazole), and 12,800 mg/L (boric acid). Non-WT isolates were detected for azoles in N. glabratus (10%-35%), C. albicans (5%-16%), and C. parapsilosis (≤ 3%). All isolates were WT for boric acid. Local ECOFFs were established for three major Candida species causing VVC, guiding the identification of non-WT isolates potentially associated with treatment failure.IMPORTANCEThe interpretation of in vitro susceptibility data of Candida isolates from women with vulvovaginal candidiasis (VVC) is challenging due to the lack of clinical breakpoints (CBPs) and epidemiological cut-off values (ECOFFs) for drugs used in VVC. In the present study, local ECOFFs were established for three major Candida species causing VVC, guiding the identification of non-wild type isolates potentially associated with treatment failure. This paper provides the framework for developing ECOFFs and ultimately CBPs that would help guide antifungal therapy of VVC.

Antifungal Effect of Poly(methyl methacrylate) with Farnesol and Undecylenic Acid against Candida albicans Biofilm Formation

The control of Candida albicans biofilm formation on dentures made of poly(methyl methacrylate) (PMMA) is an important challenge due to the high resistance to antifungal drugs. Interestingly, the natural compounds undecylenic acid (UDA) and farnesol (FAR) both prevent C. albicans biofilm formation and could have a synergetic effect. We therefore modified PMMA with a combination of UDA and FAR (UDA+FAR), aiming to obtain the antifungal PMMA_UDA+FAR composites. Equal concentrations of FAR and UDA were added to PMMA to reach 3%, 6%, and 9% in total of both compounds in composites. The physico-chemical properties of the composites were characterized by Fourier-transform infrared spectroscopy and water contact angle measurement. The antifungal activity of the composites was tested on both biofilm and planktonic cells with an XTT test 0 and 6 days after the composites' preparation. The effect of the UDA+FAR combination on C. albicans filamentation was studied in agar containing 0.0125% and 0.4% UDA+FAR after 24 h and 48 h of incubation. The results showed the presence of UDA and FAR on the composite and decreases in the water contact angle and metabolic activity of both the biofilm and planktonic cells at both time points at non-toxic UDA+FAR concentrations. Thus, the modification of PMMA with a combination of UDA+FAR reduces C. albicans biofilm formation on dentures and could be a promising anti-Candida strategy.

Antifungal susceptibility pattern of Candida species isolated from pregnant women

Introduction

Candida species, opportunistic yeast, are the second most common cause of female vulvovaginal candidiasis. This study aimed to evaluate the antifungal susceptibility profile of the isolated Candida species in pregnant women in Hajjah governorate, Yemen.

Methods

A hospital-based cross-sectional study was conducted among 396 pregnant women attending Authority AL-Gumhorri Hospital Hajjah between February and July 2023. Vaginal swabs were collected, and Candida species were isolated and identified based on the standard laboratory method. Furthermore, the antifungal drug susceptibility of Candida species was determined by the Kirby-Bauer technique.

Results and discussion

The prevalence of vaginal Candida infection among pregnant women was 61.4%. Candida albicans was the most predominant species (59.26%), followed by Candida krusei(13.58%), Candida Tropicalis (11.12%), Candida Grabata (9.87%), and Candida dubliniensis (6.17%). The highest rate of Candida infections was among women aged 24-30 years (71.9%) who finished primary school (77.8%), with the third trimester (80%), multigravida (66.1%), and recurrent infection (67.7%) showing significant differences (P < 0.05). The Candida albicans isolates were resistant to clotrimazole and itraconazole at 34.7% and 23.6%, respectively.In addition, the resistance of Candida krusei, Candida tropicalis, Candida glabrata, and Candida dublinensis isolates to fluconazole, voriconazole, voriconazole, and nystatin was 57.6%, 63%, 43.8%, and 60%, respectively. Additionally, approximately 46.2% of isolated Candida albicans exhibited one kind of antifungal drug resistance, whereas 38.7% of isolated non-albicans exhibited resistance to three different antifungal agents. According to the above findings, Candida infection is highly prevalent in Yemen and quite widespread. Interventions in health education are advised to increase women's knowledge of vaginitis and its prevention. The antifungal susceptibility test may also be helpful in determining the best medication for each patient.

Physiological adventures in Candida albicans: farnesol and ubiquinones

SUMMARYFarnesol was first identified as a quorum-sensing molecule, which blocked the yeast to hyphal transition in Candida albicans, 22 years ago. However, its interactions with Candida biology are surprisingly complex. Exogenous (secreted or supplied) farnesol can also act as a virulence factor during pathogenesis and as a fungicidal agent triggering apoptosis in other competing fungi. Farnesol synthesis is turned off both during anaerobic growth and in opaque cells. Distinctly different cellular responses are observed as exogenous farnesol levels are increased from 0.1 to 100 µM. Reported changes include altered morphology, stress response, pathogenicity, antibiotic sensitivity/resistance, and even cell lysis. Throughout, there has been a dearth of mechanisms associated with these observations, in part due to the absence of accurate measurement of intracellular farnesol levels (Fi). This obstacle has recently been overcome, and the above phenomena can now be viewed in terms of changing Fi levels and the percentage of farnesol secreted. Critically, two aspects of isoprenoid metabolism present in higher organisms are absent in C. albicans and likely in other yeasts. These are pathways for farnesol salvage (converting farnesol to farnesyl pyrophosphate) and farnesylcysteine cleavage, a necessary step in the turnover of farnesylated proteins. Together, these developments suggest a unifying model, whereby high, threshold levels of Fi regulate which target proteins are farnesylated or the extent to which they are farnesylated. Thus, we suggest that the diversity of cellular responses to farnesol reflects the diversity of the proteins that are or are not farnesylated.

A Combination of β-Aescin and Newly Synthesized Alkylamidobetaines as Modern Components Eradicating the Biofilms of Multidrug-Resistant Clinical Strains of Candida glabrata

The current trend in microbiological research aimed at limiting the development of biofilms of multidrug-resistant microorganisms is increasingly towards the search for possible synergistic effects between various compounds. This work presents a combination of a naturally occurring compound, β-aescin, newly synthesized alkylamidobetaines (AABs) with a general structure-CnTMDAB, and antifungal drugs. The research we conducted consists of several stages. The first stage concerns determining biological activity (antifungal) against selected multidrug-resistant strains of Candida glabrata (C. glabrata) with the highest ability to form biofilms. The second stage of this study determined the activity of β-aescin combinations with antifungal compounds and alkylamidobetaines. In the next stage of this study, the ability to eradicate a biofilm on the polystyrene surface of the combination of β-aescin with alkylamidobetaines was examined. It has been shown that the combination of β-aescin and alkylamidobetaine can firmly remove biofilms and reduce their viability. The last stage of this research was to determine the safety regarding the cytotoxicity of both β-aescin and alkylamidobetaines. Previous studies on the fibroblast cell line have shown that C9 alkylamidobetaine can be safely used as a component of anti-biofilm compounds. This research increases the level of knowledge about the practical possibilities of using anti-biofilm compounds in combined therapies against C. glabrata.

Farnesol as an antifungal agent: comparisons among MTL and MTLα haploid and diploid Candida albicans and Saccharomyces cerevisiae

Aims: Farnesol was identified 20 years ago in a search for Candida albicans quorum sensing molecules (QSM), but there is still uncertainty regarding many aspects of its mode of action including whether it employs farnesol transport mechanisms other than diffusion. Based on the structural similarity between farnesol and the farnesylated portion of the MTL a pheromone, we explored the effects of ploidy and mating type locus (MTL) on the antifungal activity of exogenous farnesol. Methods and results: We approached this question by examining five MTL a and five MTLα haploid strains with regard to their farnesol sensitivity in comparison to six heterozygous MTL a/ α diploids. We examined the haploid and diploid strains for percent cell death after exposure of exponentially growing cells to 0-200 µM farnesol. The heterozygous (MTL a/α) diploids were tolerant of exogenous farnesol whereas the MTL a and MTLα haploids were on average 2- and 4-times more sensitive, respectively. In the critical range from 10-40 µM farnesol their cell death values were in the ratio of 1:2:4. Very similar results were obtained with two matched sets of MAT a, MATα, and MAT a/α Saccharomyces cerevisiae strains. Conclusion: We propose that the observed MTL dependence of farnesol is based on differentially regulated mechanisms of entry and efflux which determine the actual cellular concentration of farnesol. The mechanisms by which pathogens such as C. albicans tolerate the otherwise lethal effects of farnesol embrace a wide range of physiological functions, including MTL type, ubiquinone type (UQ6-UQ9), energy availability, and aerobic/anaerobic status.

Molecular association of Candida albicans and vulvovaginal candidiasis: focusing on a solution

Candida albicans-mediated vulvovaginal candidiasis (VVC) is a significant challenge in clinical settings, owing to the inefficacy of current antifungals in modulating virulence, development of resistance, and poor penetration into the biofilm matrix. Various predisposition factors are molecular drivers that lead to the dysbiosis of normal microflora of the vagina, upregulation of central metabolic pathways, morphogenesis, hyphal extension, adhesion, invasion, and biofilm formation leading to chronic infection and recurrence. Hence, it is crucial to understand the molecular mechanism behind the virulence pathways driven by those drivers to decode the drug targets. Finding innovative solutions targeting fungal virulence/biofilm may potentiate the antifungals at low concentrations without affecting the recurrence of resistance. With this background, the present review details the critical molecular drivers and associated network of virulence pathways, possible drug targets, target-specific inhibitors, and probable mode of drug delivery to cross the preclinical phase by appropriate in vivo models.