B-Cell Epitope Mapping from Eight Antigens of Candida albicans to Design a Novel Diagnostic Kit: An Immunoinformatics Approach

Invasive candidiasis is an emerging fungal infection and a leading cause of morbidity in health care facilities. Despite advances in antifungal therapy, increased antifungal drug resistance in Candida albicans has enhanced patient fatality. The most common method for Candida albicans diagnosing is blood culture, which has low sensitivity. Therefore, there is an urgent need to establish a valid diagnostic method. Our study aimed to use the bioinformatics approach to design a diagnostic kit for detecting Candida albicans with high sensitivity and specificity. Eight antigenic proteins of Candida albicans (HYR1, HWP1, ECE1, ALS, EAP1, SAP1, BGL2, and MET6) were selected. Next, a construct containing different immunodominant B-cell epitopes was derived from the antigens and connected using a suitable linker. Different properties of the final construct, such as physicochemical properties, were evaluated. Moreover, the designed construct underwent 3D modeling, reverse translation, and codon optimization. The results confirmed that the designed construct could identify Candida albicans with high sensitivity and specificity in serum samples of patients with invasive candidiasis. However, experimental studies are needed for final confirmation.

Vulvovaginal candidiasis and asymptomatic vaginal colonization in Portugal: epidemiology, risk factors and antifungal pattern

Vulvovaginal candidiasis (VVC) has been identified as a global issue of concern due to its clinical, social and economic implications. The emerging relevance of VVC makes it crucial to increase the knowledge on its epidemiological and etiological features in order to improve its prevention and treatment. Thus, this study aimed to reveal the incidence, microbiology, antifungal pattern and risk factors of VVC in Portugal. For that, high vaginal samples were collected from 470 symptomatic and asymptomatic participants; Candida spp. were identified with molecular techniques and their antifungal susceptibility was analysed with E-tests. The results revealed an incidence of VVC among women with vulvovaginitis of 74.4%. Furthermore, 63.7% of asymptomatic women were colonized with Candida spp. Importantly, women with history of recurrent vaginal infections, those who use over-the-counter antifungals, oral contraceptive pills and non-cotton underwear were found to be at significantly higher risk of developing VVC. Candida albicans was the most common species (59%), followed by Candida glabrata (27%), in a total of 8 distinct species, with similar distribution among colonized and infected participants. Of note, various isolates, especially of the most common species, showed low susceptibility towards fluconazole. In contrast, only few isolates showed low susceptibility towards caspofungin. Overall, this study suggests that the identification of species causing VVC and their antifungal susceptibility are urgently needed in clinical practice in order to improve the decision for the most adequate treatment. It also suggests that avoiding certain risk behaviours may prevent the development of VVC.

Prevalence, species distribution and antifungal susceptibility of Candida albicans causing vaginal discharge among symptomatic non-pregnant women of reproductive age at a tertiary care hospital, Vietnam

Background

Vaginal candidiasis is frequent in women of reproductive age. Accurate identification Candida provides helpful information for successful therapy and epidemiology study; however, there are very limited data from the Vietnam have been reported. This study was performed to determine the prevalence, species distribution of yeast causing vaginal discharge and antifungal susceptibility patterns of Candida albicans among symptomatic non-pregnant women of reproductive age.

Methods

Vaginal discharge samples were collected from 462 women of reproductive age in Hanoi, Vietnam between Sep 2019 and Oct 2020. Vaginal swabs from these patients were examined by direct microscopic examination (10% KOH). CHROMagar™ Candida medium and Sabouraud dextrose agar supplemented with chloramphenicol (0.5 g/l) were used to isolate yeast, and species identification was performed using morphological tests and molecular tools (PCR and sequencing). Antifungal susceptibility testing was determined according to the Clinical and Laboratory Standards Institute guidelines (M27-A3 and M27-S4).

Results

The prevalence of vaginal yeast colonization in non-pregnant women was 51.3% of 462 participants. Nine different yeast species were identified. Among these isolates, C. albicans (51.37%) was the most frequent, followed by C. parapsilosis (25.88%), C. glabrata (11.37%), C. tropicalis (4.31%), C. krusei (3.92%), C. africana (1.57%), Saccharomyces cerevisiae (0.78%), C. nivariensis (1 isolates, 0.39%), and C. lusitaniae (1 isolates, 0.39%), respectively. Among C. albicans, all 46 isolates were 100% susceptible to micafungin, caspofungin, and miconazole. The susceptibility rates to amphotericine B, 5-flucytosine, fluconazole, itraconazole and voriconazole were 95.65, 91.30, 91.30, 82.61 and 86.95%, respectively.

Conclusions

The prevalence of VVC among symptomatic non-pregnant women of reproductive age in Vietnam was higher than many parts of the world. The high frequency of non-albicans Candida species, which were often more resistant to antifungal agents, was a notable feature. Resistance rates of vaginal C. albicans isolates to antifungal agents was low. Our findings suggest that continued surveillance of changes in species distribution and susceptibility to antifungals should be routinely screened and treated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06192-7.

Molecular identification and antifungal susceptibility profiles of Candida dubliniensis and Candida africana isolated from vulvovaginal candidiasis: A single-centre experience in Iran

Background

Vulvovaginal candidiasis (VVC) is a common and debilitating long‐term illness affecting million women worldwide. This disease is caused mainly by Candida albicans and a lesser extent by other species, including the two phylogenetically closely related pathogens Candida africana and Candida dubliniensis.

Objectives

In this study, we report detailed molecular epidemiological data about the occurrence of these two pathogenic yeasts in Iranian patients affected by VVC, or its chronic recurrent form (RVVC), and provide, for the first time, data on the antifungal activity of two new drugs, efinaconazole (EFN) and luliconazole (LUL).

Methods

A total of 133 vaginal yeast isolates, presumptively identified as Calbicans by phenotypic and restriction analysis of rDNA, were further analysed by using a specific molecular method targeting the HWP1 gene. All Cafricana and Cdubliniensis isolates were also tested for their in vitro susceptibility to a panel of modern and classical antifungal drugs.

Results and Conclusions

Based on the molecular results, among 133 germ‐tube positive isolates, we identify 119 Calbicans (89.47%), 11 Cafricana (8.27%) and 3 Cdubliniensis (2.26%) isolates. Cafricana and Cdubliniensis showed low MIC values for most of the antifungal drugs tested, especially for EFN and LUL, which exhibited a remarkable antifungal activity. High MIC values were observed only for nystatin and terbinafine. Although Calbicans remains the most common Candida species recovered from Iranian VVC/RVVC patients, our data show that its prevalence may be slightly overestimated due to the presence of difficult‐to‐identify closely related yeast, especially Cafricana.

Genetic Analysis of Candida glabrata from Candiduric Patients Using Microsatellite Length Polymorphism, Antifungal Susceptibility, and Enzymatic Profiles

Background: Candida glabrata is the second agent of candiduria with increased resistance to antifungals. Microsatellite length polymorphism (MLP) is one of the genotyping techniques used in the epidemiological investigation to improve clinical management. Objectives: We aimed to detect different genotypes of C. glabrata isolates using six microsatellite markers and the MLP technique. Moreover, our genotypes' association with other countries' genotypes was illustrated using a minimum spanning tree. We investigated in vitro antifungal susceptibility and enzymatic activity profiles of the isolates. Methods: Six microsatellite markers were amplified using multiplex-PCR for 22 C. glabrata strains isolated from urine in pediatric patients admitted to the Abuzar Children's Hospital in Ahvaz, Iran. The PCR products were presented for fragment analysis, and the size of the alleles was determined. Antifungal susceptibility tests and extracellular enzyme activities were also performed. Results: Nineteen multilocus genotypes were detected so that 22.7% of the strains had identical genotypes. The isolates were wild-type for amphotericin B (0.0625 - 2 µg/mL), itraconazole (0.125 - 2 µg/mL), and voriconazole (0.0078 - 0.00625 µg/mL). All the isolates were sensitive to fluconazole at the minimum inhibitory concentration (MIC) range (0.0312 - 16 μg/mL), and three of them were resistant to caspofungin (MIC ≥ 0.5 μg/mL). Moreover, 72.7 and 68.2% of the isolates had no phospholipase and esterase activities. The highest potency of enzymatic activity was obtained in hemolysin and proteinase enzymes. A high genetic diversity (19 genotypes of the 22 isolates) existed among the urinary C. glabrata isolates. Based on the minimum spanning tree, two clusters of our genotypes were related to C. glabrata genotypes in a previous study in Iran, and the third cluster was entirely connected with Chinese genotypes. Conclusions: Most of the isolates were the non-wild type for posaconazole but were rarely resistant to other antifungals. Hemolysin and proteinase secreted as the main virulence factors among the urinary C. glabrata isolates.

Vulvovaginal candidiasis in Iran: A systematic review and meta-analysis on the epidemiology, clinical manifestations, demographic characteristics, risk factors, etiologic agents and laboratory diagnosis

Vulvovaginal candidiasis is a global issue of concern due to its association with economic costs, sexually transmitted infections, and ascending genital tract diseases. This infection affects 75% of women on at least one occasion over a lifetime. The present systematic review and meta-analysis is the first to determine the prevalence of vulvovaginal candidiasis in Iranian women. We searched national (SID, IranDoc, Iranmedex, and Magiran) and international (PubMed, Scopus, Google Scholar, and web of science) databases for studies published between May 2000 until May 2020 reporting the epidemiologic features of vulvovaginal candidiasis in Iranian women. Inclusion and exclusion criteria were defined to select eligible studies. Data were extracted and presented according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The results of the meta-analysis were visualized as a forest plot representing the prevalence estimates of each study. Heterogeneity was also analyzed using the I², and Chi² statistics. The literature search revealed 1929 studies, of which 39 studies met the eligibility criteria, consisting of 10536 women with vulvovaginal symptoms from 24 different cities covering all parts of Iran. The city with the highest number of studies was Tehran (5/39). The overall prevalence of vulvovaginal candidiasis among Iranian women was 47% (95% CI, 0/38-0/55%) and Candida albicans was the most prevalent etiologic agent. The use of oral contraceptive pills (OCPs) was the predominant risk factor for developing vulvovaginal candidiasis and vaginal cheese-like discharges were the predominant clinical manifestation in Iranian women suffering from vulvovaginal candidiasis. The 25-34-year-old age group has the highest prevalence. A high level of I² (I² = 98.7%, P = 0.000) and Chi² (Chi² = 2993.57, P < 0.001) was obtained among studies, which provides evidence of notable heterogeneity between studies. The present meta-analysis revealed a high prevalence of vulvovaginal candidiasis in Iranian women. Given that this infection is associated with the enhanced susceptibility to sexually transmitted diseases (HIV, chlamydia, genital herpes, genital warts, gonorrhea, hepatitis, syphilis, and trichomoniasis) and also is related to the increased probability of preterm birth, congenital cutaneous candidiasis, preterm labor, and infertility, taking preventive measures such as awareness of patients as well as monitoring and controlling of the syndrome are essential.

Molecular Characterization and Antifungal Susceptibility of Candida Species Isolated From Vulvovaginitis in Jahrom City, South of Iran

Background: Vulvovaginal candidiasis (VVC) is a significant health issue due to Candida spp. Although Candida albicans is considered a major causative agent of vaginal candidiasis, non-albicans species have increased during previous decades. Objectives: This research aimed at molecular identification and assessing antifungal susceptibility of VVC isolated Candida spp. Methods: A professional physician examined two hundred and ninety-five suspected females with vaginitis. The specimens were collected by sterile cotton swabs. Swabs were inoculated on Sabouraud dextrose agar plates and then incubated for 48 - 72 hours at 35°C. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to detect all Candida species. Broth microdilution, according to the M27-A3 and M27-S4 CLSI documents, were employed for determining the antifungal susceptibility tests of caspofungin (CAS), voriconazole (VRC), itraconazole (ITC), fluconazole (FLU), clotrimazole (CLO), ketoconazole (KTO), amphotericin B (AMB), and nystatin (NYS). Results: A total of 295 females suspected of vulvovaginal candidiasis were examined. The culture results were positive in 50.5% (149 of 295) of specimens. According to molecular identification techniques, C. albicans 133/149 (89.2%), C. glabrata 8/149 (5.4%), and C. kefyr 2/149 (1.4%) were the main species. A mixed infection of C. albicans and C. glabrata 6/149 (4 %) was detected. The geometric mean values to all Candida strains were in increasing order as the following: CAS, 0.075 µg/mL; VRC, 0.091 µg/mL; ITC, 0.15 µg/mL; AMB, 0.22 µg/mL; CLO, 0.23 µg/mL; KTO, 0.28 µg/mL; NYS, 0.88 µg/mL; FLU, 1.48 µg/mL. Further, the MIC ranges of all Candida isolates to the tested antifungal agents were in increasing order as follows: CAS: 0.031 - 0.25 µg/mL, KTO and ITC: 0.031 - 2 µg/mL, VRC: 0.031 - 4 µg/mL, CLO and AMB: 0.031 - 8 µg/mL, NYS: 0.06 - 4 µg/mL, and FLU: 0.12 - 128 µg/mL. Conclusions: We reported 1 (7.2 %) C. glabrata isolate resistance to FLU and 2 (14.3%) C. glabrata isolates susceptible-dose-dependent (SDD) to CAS. We also reported 6 (4.5%), 5 (3.8%), and 2 (1.5%) C. albicans resistance to ITC, FLU, and AMB, respectively, but 100% C. albicans susceptible to CAS and VRC.

Molecular Investigation of Etiologic Agents Causing Vulvovaginal Candidiasis

Background: Vulvovaginal candidiasis (VVC) is an ordinary infection caused by Candida species. Meanwhile, a shift towards non-albicans Candida (NAC) species has been detected in VVC patients. Objectives: This study aimed at molecular identification of Candida isolates, causing VVC. Methods: Vaginal secretion samples of 320 non-pregnant vaginitis patients at Shahid Akbar-Abadi Obstetrics and Gynecology Hospital in Tehran (Iran) were collected. Samples were evaluated using mycological and molecular approaches. Vaginitis isolates were analyzed with the PCR using NL1 and NL4 primers, and the D1/D2 region of the large-subunit rRNA gene was amplified and sequenced. Results: In total, 100 Candida isolates were identified from VVC and recurrent vulvovaginal candidiasis (RVVC). Candida albicans was the most frequent (51%), followed by C. glabrata (36%), C. krusei (Pichia kudriavzevii) (8%), and C. kefyr (Kluyveromyces marxianus) (5%). 51 and 49% of isolates had C. albicans and NAC, respectively. Conclusions: Candida albicans and C. glabrata were the most common agents of vulvovaginal candidiasis. NAC spp. (49%) was found as an important agent associated with VVC.