Differential response of Candida species morphologies and isolates to fluconazole and boric acid

Candida albicans is the most prevalent cause of vulvovaginal candidiasis ('yeast infection') and recurrent vulvovaginal candidiasis, though the incidence of non-albicans yeast species is increasing. The azole fluconazole is the primary antifungal drug used to treat R/VVC yet isolates from some species have intrinsic resistance to fluconazole, and recurrent infection can occur even with fluconazole-susceptible populations. The second-line broad-spectrum antimicrobial drug, boric acid, is an alternative treatment that has been found to successfully treat complicated VVC infections. Far less is known about how boric acid inhibits growth of yeast isolates in different morphologies compared to fluconazole. We found significant differences in drug resistance and drug tolerance (the ability of a subpopulation to grow slowly in high levels of drug) between C. albicans, C. glabrata, and C. parapsilosis isolates, with the specific relationships dependent on both drug and phenotype. Population-level variation for both susceptibility and tolerance was broader for fluconazole than boric acid in all species. Unlike fluconazole, which neither prevented hyphal formation nor disrupted mature biofilms, boric acid inhibited C. albicans hyphal formation and reduced mature biofilm biomass and metabolic activity in all isolates in a dose-dependent manner. Variation in planktonic response did not generally predict biofilm phenotypes. Overall, our findings illustrate that boric acid is broadly effective at inhibiting growth across many isolates and morphologies, which could explain why it is an effective treatment for R/VVC.

Antifungal Activity of Natural Compounds vs. Candida spp.: A Mixture of Cinnamaldehyde and Eugenol Shows Promising In Vitro Results

Candida spp. are commensal organisms of the skin, mucous membranes, gastrointestinal tract, blood, and vagina of animals and humans. In recent decades, the incidence of human fungal infections has increased, with Candida spp. (mainly C. albicans) infections being the most frequent, and the treatment of fungal infections is still a clinical challenge. Colonization of the human gastrointestinal tract by Candida spp. is significant because infections (e.g., candidemia and vulvovaginal candidiasis) frequently arise from commensal microorganisms. The aim of this study was to test in vitro the antifungal activity and the eventual synergistic effect of five pure components of essential oils: cinnamaldehyde, α-pinene, limonene, eucalyptol, and eugenol. These compounds were tested on 18 Candida strains (15 C. albicans, 2 C. glabrata, and 1 C. lusitaniae) derived from a culture collection of vaginal clinical strains. Methods: Fungistatic activity was evaluated using the disk diffusion method. For fungicidal activity, microdilution and time–kill curve protocols were set up. The checkerboard method was chosen to evaluate a possible synergistic effect of these compounds when mixed. Results: Cinnamaldehyde and eugenol gave the best results, inhibiting all the Candida strains and showing a highly additive effect (FICI 0.625). The cinnamaldehyde inhibition zone (IZ), MIC, and MFC means were 69 mm, 50.05 mg/L, and 109.26 mg/L respectively. Cinnamaldehyde led to the total loss of viable Candida cells within 4 h. Eugenol IZ, MIC, and MFC means were 35.2 mm, 455.42 mg/L, and 690.09 mg/L, respectively. Eugenol led to the total loss of viable fungal cells within 1 h. Treatment with α-pinene inhibited 88.9% of Candida strains, with an IZ mean of 21.2 mm, a MIC mean of 195.41 mg/L, and a MFC mean of 251.27 mg/L; this compound led to the total loss of viable fungal cells only after 24 h. Limonene inhibited only 33.3% of the tested strains and eucalyptol did not produce an inhibition halo, so these compounds were not tested further. Conclusions: These characteristics, together with the well-known safety of cinnamaldehyde and eugenol for human use, make these two natural compounds the perfect candidates for the treatment of candidiasis. This was a pilot study, the purpose of which was to evaluate the best composition of a mixture to be used against intestinal and vulvovaginal candidiasis; in vivo studies are needed to confirm these very encouraging results.

THE PREVALENCE OF VULVOVAGINAL CANDIDIASIS (VVC) AMONG WOMEN SUFFERING VAGINITIS ATTENDED A PRIVATE GYNECOLOGICAL CLINIC, ADEN-YEMEN

The study was carried out to determine the prevalence of vulvovaginal candidiasis among women suffering vaginitis. This prospective cross-sectional study was conducted among 120 women between the age of 15 to 45 years (mean age 39 years), attended a private gynecological clinic in Aden with symptoms of vaginitis between January and June 2019. A questionnaire was used to obtain information on the participants’ sociodemographic data and medical history. Direct microscopic examination (10% KOH), culture on SDA, germ tube test and gram staining were used to determine the prevalence of vulvovaginal candidiasis and to differentiate between C.albicans and non-albicans species. Out of 120 women, 25 (20.8%) were diagnosed with vulvovaginal candidiasis (VVC) and 95 (79.2%) with non-candidal vaginitis. C.albicans was the most prevalent with a prevalence rate of 17.5%. Although not statistically significant, vulvovaginal candidiasis tended to be more prevalent among women with 25-34 years. No statistically significant association between the prevalence of vulvovaginal candidiasis and educational level and marital status. Vulvovaginal candidiasis (VVC) was slightly high in Aden and Candida albicans was the most common causative agent of VVC. In the clinical diagnosis of VVC, both clinical criteria and microbiological tests must be used. Further study is needed to find out the prevalence of RVVC among women in the Aden governorate.

Management of patients with herpes-associated recurrent vulvovaginal candidiasis

Objective. To develop a diagnostic algorithm, a rational method of treatment, and principles of preconception care in women with herpes-associated recurrent vulvovaginal candidiasis (RVVC).Materials and methods. We examined 68 patients with herpes-associated RVVC and 20 gynecologically healthy women.Results. It has been found that in RVVC it is necessary to study vaginal swab culture with the determination of the microorganism and its biofilm-forming ability in combination with viral DNA detection by the polymerase chain reaction (PCR) in vaginal secretion, determination of the IgG titer to the herpes simplex virus (HSV), the avidity index to HSV I and II. In the presence of laboratory-confirmed RVVC and HSV infection, it is necessary to assume the presence of an atypical course of HSV infection followed by complex antiviral and antimycotic therapy.Conclusion. The use of the developed algorithm of diagnostic and treatment interventions as preconception care makes it possible to address symptoms, reduce relapse rates and extend a non-relapse interval, prepare women with the mixed-infection for favorable pregnancy outcomes.

Candida albicans Modulates Murine and Human Beta Defensin-1 during Vaginitis

Vulvovaginal candidiasis (VVC) and recurrent vulvovaginal candidiasis (RVVC) are two forms of a disease caused by Candida spp. β-defensin (BD) is one of the most important families of antimicrobial peptides in the female genital tract and includes molecules that exert essential local functions as antimicrobial and PMN chemoattractant peptides. However, the information on their role during murine and human VVC and RVVC is limited. Thus, we analyzed the behavior and contribution of BD1 to the local response in a VVC mice model and the local cytokine profile and human BD1 and BD3 expression in cervicovaginal lavage from patients with VVC and RVVC. We demonstrated that, in patients with RVVC BD1, mRNA and protein expression were severely diminished and that the aspartate proteinase and lipase secreted by C. albicans are involved in that decrease. This study provides novel information about the pathogenesis of VVC and describes a highly efficient C. albicans escape strategy for perpetuating the infection; these results may contribute to the development of new or combined treatment approaches.

A variant ECE1 allele contributes to reduced pathogenicity of Candida albicans during vulvovaginal candidiasis via altered secretion of candidalysin

Background: Candida albicans is the primary etiological agent of vulvovaginal candidiasis (VVC) and exerts its pathogenicity through secretion of the peptide toxin candidalysin encoded by the ECE1 gene. A highly conserved variant ECE1 sequence exists across a diverse set of clinical isolates. Thus, we sought to determine the relative pathogenicity and mechanism(s) associated with this alternative ECE1 allele. Methods: Isogenic strains harboring WT or variant ECE1 sequences were engineered in an Δ/Δece1 background. After confirmation of equivalent expression by qPCR, pathogenicity of strains were tested using in vitro epithelial cell and in vivo VVC models of infection and LDH, IL-1β, neutrophil levels monitored. Follow up studies using synthetic candidalysin peptide were also performed. Lastly, a panel of ECE1 chimeras were constructed to assess potential processing defects and detected by a novel HiBiT-tagging approach. Results: Strains transformed with either the variant full length ECE1 or candidalysin allele, as compared to the WT sequence, demonstrated significantly reduced immunopathogenicity during in vitro or in vivo infection despite equivalent fungal burden. Interestingly, epithelial challenge with WT or variant synthetic peptide revealed similar capacity to elicit damage and IL-1β. Allele profiling and ECE1 chimera experiments demonstrated that defects in pathogenicity are at least partly due to inefficient ECE1 processing at the peptide 2-peptide 3 junction. Discussion: The ECE1 gene displays conserved polymorphisms that alter candidalysin secretion and strain pathogenicity. Future work is focused on determining specific amino acid sequences that contribute to these affects across clinical isolates and disease states.