Production of a hemolytic factor by Candida albicans

New arsenals for old armour: Biogenic nanoparticles in the battle against drug-resistant Candidaalbicans

Candida albicans is a common commensal fungus and fourth most frequent causative agent of nosocomial infections including life-threatening invasive candidiasis in humans. The effectiveness of present antifungal therapies using azoles, polyenes, flucytosine and echinocandins has plateaued in managing fungal infections. The limitations of these antifungal drugs are related to polymorphic morphology, biofilm formation, emergence of drug-resistant strains and production of several virulence factors. Development of new antifungal agents, which can particularly afflict multiple cellular targets and limiting evolving resistant strains are needed. Recently, metal nanoparticles have emerged as a source of new antifungal agents for antifungal formulations. Furthermore, green nanotechnology deals with the use of biosynthetic routes that offer new avenue for synthesizing antifungal nanoparticles coupled with less toxic chemical inventory and environmental sustainability. This article reviews the recent developments on C. albicans pathogenesis, biofilm formation, drug resistance, mode of action of antifungal drugs and antifungal activities of metal nanoparticles. The antifungal efficacy and mode of action of metal nanoparticles are described in the context of prospective therapeutic applications.

The intricate link between iron, mitochondria and azoles in Candida species

Invasive fungal infections are rapidly increasing, and the opportunistic pathogenic Candida species are the fourth most common cause of nosocomial systemic infections. The current antifungal classes, of which azoles are the most widely used, all have shortcomings. Azoles are generally considered fungistatic rather than fungicidal, they do not actively kill fungal cells and therefore resistance against azoles can be rapidly acquired. Combination therapies with azoles provide an interesting therapeutic outlook and agents limiting iron are excellent candidates. We summarize how iron is acquired by the host and transported towards both storage and iron-utilizing organelles. We indicate whether these pathways alter azole susceptibility and/or tolerance, to finally link these transport mechanisms to mitochondrial iron availability. In this review, we highlight putative novel intracellular iron shuffling mechanisms and indicate that mitochondrial iron dynamics in relation to azole treatment and iron limitation is a significant knowledge gap.

In Vitro Evaluation of the Virulence Attributes of Oropharyngeal Candida Species Isolated from People Living with Human Immunodeficiency Virus with Oropharyngeal Candidiasis on Antiretroviral Therapy

Background

Oropharyngeal Candida species are part commensal microflora in the the oral cavity of health individuals. Commensal Candida species can become opportunist and transition to pathogenic causes of oropharyngeal candidiasis (OPC) in individuals with impaired immunity through ecological cues and expression of virulence factors. Limited studies have evaluated virulence attributes of oropharyngeal Candida species among people living with human immunodeficiency virus (PLHIV) with OPC on antiretroviral therapy (ART) in Uganda.

Objective

Evaluation of the Virulence Attributes of Oropharyngeal Candida Species Isolated from People Living with Human Immunodeficiency Virus with Oropharyngeal Candidiasis on Antiretroviral Therapy.

Methods

Thirty-five (35) Candida isolates from PLHIV with OPC on ART were retrieved from sample repository and evaluated for phospholipase activity using the egg yolk agar method, proteinase activity using the bovine serum albumin agar method, hemolysin activity using the blood agar plate method, esterase activity using the Tween 80 opacity test medium method, coagulase activity using the classical tube method and biofilm formation using the microtiter plate assay method in vitro.

Results

Phospholipase and proteinase activities were detected in 33/35 (94.3%) and 31/35 (88.6%) of the strains, respectively. Up to 25/35 (71.4%) of the strains exhibited biofilm formation while esterase activity was demonstrated in 23/35 (65.7%) of the strains. Fewer isolates 21/35 (60%) of the strains produced hemolysin and coagulase production was the least virulence activity detected in 18/35 (51.4%).

Conclusion

Phospholipase and proteinase activities were the strongest virulence attributes of oropharyngeal Candida species.

Assessment of species distribution and virulence factors of oral fungal carriage among hospitalized patients with COVID-19: a case-control study

Background

The COVID-19 pandemic highlighted the need to study oral fungal carriage and its potential impact. In oral fungal environments, factors like changes in respiratory epithelium, increased pathogen attachment, local inflammation, and virulence factors could influence COVID-19 severity. The authors conducted a study to explore oral fungal carriage in COVID-19 patients and compare it to a healthy control group.

Methods

The authors executed a case-control investigation including 144 COVID-19 patients and an equivalent number of 144 healthy controls. The matching criteria encompassed age, sex, body mass index, and the history of antibiotic and antiviral medication intake. This research was performed over a span of 12 months from May 2021 to May 2022. The mouth area was sampled with a cotton-tipped swab. Subsequently, all the samples underwent fungal culture and PCR-sequencing procedures.

Results

In COVID-19 patients, oral fungal carriage was three times higher compared to healthy controls. Candida was the exclusive genus found in both groups, with Candida albicans being the most frequently isolated species (90.79%). Among COVID-19 patients, Candida species showed significantly higher esterase, proteinase, and hemolysin activity compared to healthy individuals. Both groups exhibited elevated levels of C. albicans virulence factors compared to non-albicans species.

Conclusions

It is crucial to understand the way that virulence factors of oral fungal carriage act in COVID-19 patients in order to come up with novel antifungal medications, identify the contributing factors to drug resistance, and manage clinical outcomes.

On the Way to the Technological Development of Newly Selected Non-Saccharomyces Yeasts Selected as Innovative Biocontrol Agents in Table Grapes

Post-harvest decay of fresh table grapes causes considerable annual production losses. The main fungal agents of decay both in pre- and post-harvest are B. cinerea, Penicillium spp., Aspergillus spp., Alternaria spp., and Cladosporium spp. To date, the use of agrochemicals and SO2 are the main methods to control grape molds in pre- and postharvest, respectively. Significant improvements, however, have already been made in to apply innovative and more environmentally sustainable control strategies, such as Biological Control Agents (BCAs), which can reduce disease severity in both pre- and post-harvest. In this study, 31 new non-Saccharomyces yeast strains, isolated from berries of native Apulian table grape genotypes, were tested for their in vivo effectiveness against grey mold of table grapes, resulting in two St. bacillaris ('N22_I1' and 'S13_I3'), one S. diversa ('N22_I3'), one A. pullulans ('OLB_9.1_VL') and one H. uvarum ('OLB_9.1_BR') yeast strains that were marked as efficient and good BCAs. Their mechanisms of action were characterized through in vitro assays, and additional characteristics were evaluated to assess the economic feasibility and viability for future technological employment. Their effectiveness was tested by reducing the working concentration, their antagonistic effect on a wide range of fungal pathogens, their ability to survive in formulations with long shelf life, and their safety to human health.

Pharmacodynamic, pharmacokinetic, toxicity, and recent advances in Eugenol's potential benefits against natural and chemical noxious agents: A mechanistic review

The active biological phytochemicals, crucial compounds employed in creating hundreds of medications, are derived from valuable and medicinally significant plants. These phytochemicals offer excellent protection from various illnesses, including inflammatory disorders and chronic conditions caused by oxidative stress. A phenolic monoterpenoid known as eugenol (EUG), it is typically found in the essential oils of many plant species from the Myristicaceae, Myrtaceae, Lamiaceae, and Lauraceae families. One of the main ingredients of clove oil (Syzygium aromaticum (L.), Myrtaceae), it has several applications in industry, including flavoring food, pharmaceutics, dentistry, agriculture, and cosmeceuticals. Due to its excellent potential for avoiding many chronic illnesses, it has lately attracted attention. EUG has been classified as a nonmutant, generally acknowledged as a safe (GRAS) chemical by the World Health Organization (WHO). According to the existing research, EUG possesses notable anti-inflammatory, antioxidant, analgesic, antibacterial, antispasmodic, and apoptosis-promoting properties, which have lately gained attention for its ability to control chronic inflammation, oxidative stress, and mitochondrial malfunction and dramatically impact human wellness. The purpose of this review is to evaluate the scientific evidence from the most significant research studies that have been published regarding the protective role and detoxifying effects of EUG against a wide range of toxins, including biological and chemical toxins, as well as different drugs and pesticides that produce a variety of toxicities, throughout view of the possible advantages of EUG.

Genotypes and virulence-related activities of Candida albicans derived from oral cavity of patients in Hokkaido

OBJECTIVE

This study aimed to elucidate the difference in virulence of Candida albicans derived from oral candidiasis and non-oral candidiasis patients, and its genotype differences in Hokkaido to obtain a clue of a platform to develop new approaches for diagnosis and treatment.

DESIGN

C. albicans strains were collected from patients who visited the Hokkaido University Hospital Dental Center. Each strain was examined to i) identify the Candida albicans genotype by PCR, ii) measure the strain's extracellular secretory enzyme activity, iii) determine the strain's ability to induce the production of interleukin-8, and iv) determine the strain's ability to induce cell death.

RESULTS

Certain virulence-related protease activities and cytotoxicity were higher in strains derived from patients with oral candidiasis compared with strains derived from patients without oral candidiasis. This is the first report on genotypes and the virulence-related activities, such as some protease secretion, IL-8 induction and cytotoxicity of C. albicans in Hokkaido.

CONCLUSIONS

The virulence-related activities of the fungal strain may influence the pathogenesis of oral candidiasis, such as production of secreted aspartyl protease and cytotoxicity. In addition, C. albicans genotype C may be important for pathogenicity in Hokkaido, because the ratio of genotype C was increased in strains derived from oral candidiasis patients.

Candidiasis in breast cancer: Tumor progression or not?

Candida albicans is an "opportunistic fungal agent" in cancer patients that can become colonized in both mucosal and deep tissues and cause severe infections. Most evidence has shown that C. albicans can enhance the progress of different cancers by several mechanisms such as generating virulence factors, participation in endogenous production of pro-inflammatory mediators, and stimulating a wide range of immune cells in the host. The main idea of this review is to describe a range of Candida-used mechanisms that are important in candidiasis-associated malignant processes and cancer development, particularly breast cancer. This review intends to provide a detailed discussion on different regulatory mechanisms of C. albicans that undoubtedly help to open new therapeutic horizons of cancer therapy in patients with fungal infection. The current therapeutic approach is not fully effective in immunocompromised and cancer patients, and further studies are required to find new products with effective antifungal properties and minimal side effects to increase the susceptibility of opportunistic fungal infections to conventional antifungal agents. So, in this situation, a special therapy should be considered to control the infection and simultaneously have the most therapeutic index on tumor patients.

Phenotypic Investigation of Virulence Factors, Susceptibility to Ceragenins, and the Impact of Biofilm Formation on Drug Efficacy in Candida auris Isolates from Türkiye

Candida auris has emerged as a significant fungal threat due to its rapid worldwide spread since its first appearance, along with its potential for antimicrobial resistance and virulence properties. This study was designed to examine virulence characteristics, the efficacy of ceragenins, and biofilm-derived drug resistance in seven C. auris strains isolated from Turkish intensive care patients. It was observed that none of the tested strains exhibited proteinase or hemolysis activity; however, they demonstrated weak phospholipase and esterase activity. In addition, all strains were identified as having moderate to strong biofilm formation characteristics. Upon determining the minimum inhibitory concentrations (MIC) of ceragenins, it was discovered that CSA-138 exhibited the highest effectiveness with a MIC range of 1-0.5 µg/mL, followed by CSA-131 with a MIC of 1 µg/mL. Also, antimicrobial agents destroyed mature biofilms at high concentrations (40-1280 µg/mL). The investigation revealed that the strains isolated from Türkiye displayed weak exoenzyme activities. Notably, the ceragenins exhibited effectiveness against these strains, suggesting their potential as a viable treatment option.

Biochemical typing and evaluation of pathogenicity in vulvovaginal isolates of Candida albicans complex

Introduction

Candida albicans, C. dubliniensis, and C. africana form the Candida albicans complex.

Objective

To identify the phenotypic and pathogenic characteristics of isolates of the C. albicans complex preserved in a collection.

Materials and methods

Three hundred presumptive strains of the C. albicans complex were evaluated using CHROMagarTM Candida. Germ tube production was determined by three methods, chlamydospores formation was assessed and colonies were characterized in artisanal agars (Rosmarinus officinalis and Nicotiana tabacum). MALDI-TOF was used as the gold standard identification test. To detect pathogenicity factors, we evaluated the hemolytic activity of each isolate and cocultured with Staphylococcus aureus, coagulase enzyme production, and biofilm formation.

Results

Out of the 300 isolates, 43.7% produced germ tube in the heart-brain infusion broth and 47% of the isolates produced chlamydospores. In the artisan media, 6% of the isolates produced brown colonies on rosemary agar and 5% did so on tobacco agar. None of the strains hemolyzed the blood agar alone or cocultured with S. aureus. However, 50% of the isolates hemolyzed the potato dextrose agar supplemented with blood. All strains were coagulase producers, and biofilm production was variable. For germ tube production, the human serum method showed the same positivity as the milk broth method. All isolates were identified as C. albicans by MALDI-TOF.

Conclusions

The use of proteomics, molecular tests or a combination of methods is required for species identification.

Assessing pH-dependent activities of virulence factors secreted by Candida albicans

Candida albicans is an opportunistic pathogen that can thrive under adverse conditions including suboptimal pH, nutrient scarcity, and low levels of oxygen. Its pathogenicity is associated with the production of virulence factors such as extracellular hydrolytic enzymes and toxins. This study was aimed at determining the effect of external pH, substrate nature, and strain origin on protease, lipase, and hemolysin production. To achieve this objective, agar plate assays were performed at pH 5.0, 6.5, and 7.5 with substrates suitable for the detection of each family of enzymes. Moreover, the study was conducted with 20 clinical C. albicans isolates from blood, oral cavity, skin, urine, and vagina. The hydrolytic zones formed around the colonies were further measured to calculate the Ez (enzymatic zone) indexes. We found that detection of proteases in skim milk agar plates was possible for most isolates only at pH 5 (80%) and pH 6.5 (75%), whereas BSA plates could confer protease detection exclusively at pH 5 (80%). Similarly, the percentage of isolates possessing lipolytic activities was higher at pH 5 (90%) than at pH 6.5 (70%) and pH 7.5 (35%). In contrast, hemolytic activities were detected in all isolates at pH 6.5 and 7.5 but not at pH 5. Further analysis revealed that some differences in the detected activities could potentially be attributed to the anatomical origin of these isolates. Collectively, these findings suggest that the pH of the site of infection might be critical for mimicking the microenvironment employed to experimentally discover the key virulence factors.

Profiling of potential pathogenic candida species in obesity

PURPOSE OF RESEARCH

The aim of the current study was gut profiling of culturable Candida species and their possible pathogenic potential to asses role in obesity.

METHODS

This case control study includes stool samples from 75 obese individuals and 50 controls. Isolation and identification of various Candida species was carried out by standard microbiological techniques. For pathogenic profiling, extracellular enzymatic assays, biofilm forming ability and resistance to azole were analyzed.

RESULTS

Culturable gut profiling identified comparative higher abundance and diversity of Candida species among obese compared to controls. The most abundant specie among both groups was C.kefyr. A comparatively higher pathogenic potential as more hydrolases expression was detected in C.kefyr, C.albicans and Teunomyces krusei from obese group. Majority isolates from obese group were strong biofilm formers (47.1%) compared to control group (35.4%) suggesting it as strong risk factor for obesity. Fluconazole resistance was highest among C.kefyr (51%) followed by Teunomyces krusei and C.albicans. All the isolates from different species were voriconazole sensitive except C.kefyr displaying a 4.2% resistance in obese group only. A significant association of dominant colonizing species with meat, fruit/vegetable consumption and residence area was present (p < 0.05).

CONCLUSION

The presence of hydrolytic enzymes in gut Candida species showed strong association with protein's degradation and enhanced pathogenicity. C.kefyr and Teunomyces krusei has emerged as potential pathogen showing increased colonization as result of protein rich and low carb diet. Thus presenting it as a bad choice for weight loss in obese individuals.

Candidalysin Is the Hemolytic Factor of Candida albicans

Candida albicans produces an important virulence factor, the hypha-associated Ece1-derived secreted peptide toxin candidalysin, which is crucial for the establishment of mucosal and systemic infections. C.&nbsp;albicans has also long been known to be hemolytic, yet the hemolytic factor has not been clearly identified. Here, we show that candidalysin is the hemolytic factor of C.&nbsp;albicans. Its hemolytic activity is modulated by fragments of another Ece1 peptide, P7. Hemolysis by candidalysin can be neutralized by the purinergic receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid (PPADS). PPADS also affects candidalysin's ability to intercalate into synthetic membranes. We also describe the neutralization potential of two anti-candidalysin nanobodies, which are promising candidates for future anti-Candida therapy. This work provides evidence that the historically proposed hemolytic factor of C.&nbsp;albicans is in fact candidalysin and sheds more light on the complex roles of this toxin in C.&nbsp;albicans biology and pathogenicity.

Evaluation of Candida spp. and Other Fungi in Feces from Dogs with Naturally Occurring Diabetes Mellitus

Simple Summary

Diabetes mellitus is a common endocrine disorder in dogs that is similar to type 1 diabetes mellitus (T1DM) in humans. Candida spp. is a common non-pathogenic fungi that is identified more commonly and in higher amounts in humans with T1DM, including the gastrointestinal tract. This change to the distribution of microorganisms that inhabit the intestine has potential to affect glycemic control and even spread to other organs and cause severe illness. There are no studies that have investigated whether diabetic dogs, like humans, have alterations to the intestinal mycobiome. Therefore, our study sought to determine whether differences exist in the types of fungi cultured from feces in diabetic dogs and non-diabetic healthy control dogs. In addition, we wanted to find out if there were variables associated with fungi colonization. Diabetic dogs had more quantitative fungal growth than controls and females were more likely to yield growth than males. Diabetic dogs were also more likely to have Candida spp. colonized from feces. Glycemic control was also seemingly associated with growth of Candida spp. in diabetic dogs. Our results indicate that the intestinal mycobiome is altered in diabetic dogs with increased prevalence of Candida spp. and quantitative growth of fungi.

Abstract

Diabetes mellitus is a common endocrinopathy in dogs and in most cases is analogous to type 1 diabetes mellitus (T1DM) in humans. Candida spp. is a common commensal fungi with higher prevalence and magnitude of growth in humans with T1DM. There is currently no published information about the fungal microbiome in diabetic dogs. Therefore, the objectives of this study were to (i) determine whether diabetic dogs were more likely to have Candida spp. or other types of fungi from feces compared to non-diabetic controls, and (ii) identify variables associated with fungi colonization. Fourteen diabetic dogs and 14 age, sex, and breed matched non-diabetic healthy control dogs were included in this prospective case–control study. Matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was used for fungal identification. Diabetic dogs had greater quantitative fungal growth compared to controls (p = 0.004). Moreover, female dogs were more likely to have fungi colonization than males (p = 0.02). All instances of Candida spp. and Aspergillus spp. colonization were exclusively identified in diabetic dogs. Serum fructosamine concentration was higher in diabetic dogs with fecal colonization of Candida spp. compared to diabetic dogs without growth (p = 0.03). Our results indicate that the fungal microbiome in feces is altered in diabetic dogs, which seem to favor an increased prevalence of Candida spp. and higher quantitative fungal growth. Moreover, female sex and glycemic control could affect the intestinal mycobiome.

Role of Iron and Iron Overload in the Pathogenesis of Invasive Fungal Infections in Patients with Hematological Malignancies

Iron is an essential trace metal necessary for the reproduction and survival of fungal pathogens. The latter have developed various mechanisms to acquire iron from their mammalian hosts, with whom they participate in a continuous struggle for dominance over iron. Invasive fungal infections are an important problem in the treatment of patients with hematological malignancies, and they are associated with significant morbidity and mortality. The diagnosis of invasive clinical infections in these patients is complex, and the treatment, which must occur as early as possible, is difficult. There are several studies that have shown a possible link between iron overload and an increased susceptibility to infections. This link is also relevant for patients with hematological malignancies and for those treated with allogeneic hematopoietic stem cell transplantation. The role of iron and its metabolism in the virulence and pathogenesis of various invasive fungal infections is intriguing, and so far, there is some evidence linking invasive fungal infections to iron or iron overload. Clarifying the possible association of iron and iron overload with susceptibility to invasive fungal infections could be important for a better prevention and treatment of these infections in patients with hematological malignancies.

Oropharyngeal Candidiasis among Egyptian COVID-19 Patients: Clinical Characteristics, Species Identification, and Antifungal Susceptibility, with Disease Severity and Fungal Coinfection Prediction Models

The study aimed to investigate the causative species, antifungal susceptibility, and factors associated with oropharyngeal candidiasis (OPC) among Egyptian COVID-19 patients. This is an observational, case-controlled, single-center study that included three groups: COVID-19 patients (30), COVID-19 patients with OPC (39), and healthy individuals (31). Patients’ demographic data (age, sex), laboratory tests, comorbidities, treatment, and outcomes were included. Candida species were isolated from COVID-OPC patient’s oropharyngeal swabs by convenient microbiological methods. Isolated strains were tested for antimicrobial susceptibility, biofilm production, aspartyl protease, and phospholipase activities. The most common respiratory symptoms reported were dyspnea (36/39; 92.4%) and cough (33/39; 84.7%). Candida albicans was the most common isolated species, accounting for 74.36% (29/39), followed by Candida tropicalis and Candida glabrata (15.38% and 10.26%, respectively). Amphotericin was effective against all isolates, while fluconazole was effective against 61.5%. A total of 53.8% of the isolates were biofilm producers. The phospholipase activity of C. albicans was detected among 58.6% (17/29) of the isolates. Significant variables from this study were used to create two equations from a regression model that can predict the severity of disease course and liability to fungal infection, with a stativity of 87% and 91%, respectively. According to our findings, COVID-19 patients with moderate to severe infection under prolonged use of broad-spectrum antibiotics and corticosteroids should be considered a high-risk group for developing OPC, and prophylactic measures are recommended to be included in the treatment protocols. In addition, due to the increased rate of fluconazole resistance, other new antifungals should be considered.

Multilocus Sequence Typing and Antifungal Susceptibility of Candida albicans Isolates From Milk and Genital Tract of Dromedary Camel

Multilocus sequence typing (MLST) was used to study the genetic diversity and population structure of 48 Candida albicans (C. albicans) isolates from the udder or genital tract of apparently healthy or diseased camels. This study aimed also to determine the frequency of C. albicans isolates in the genital tract and udder of healthy or diseased female dromedary camels. A total of 240 mature dromedary camels (230 females and 10 males) were categorized based on the clinical examination of gentile tract and udder into five groups [fertile females (n = 70), infertile females (n = 115), healthy udder (n = 15), mastitis (n = 30), and fertile males (n = 10)]. Swabs were collected from male and female genital tracts of dromedary camels and milk samples were collected from healthy and diseased udders. C. albicans was isolated from 20% of the samples. The frequency of isolation was significantly higher (p < 0.00001) in disease camels (75%) compared with apparently healthy camels (25%). Most of C. albicans was isolated from infertile female genitalia (62.50%) which was significantly higher than that isolated from fertile female genitalia (16.67%). Multilocus sequence (MLS) analysis identified seven different diploid sequence types (DSTs) including DST2, DST50, DST62, DST69, DST124, DST142, and DST144. The most frequently identified DTS was DST69 (13/48) which significantly higher (p ≤ 0.05) than DST2, DST62, and DST124. The frequency of identification of DST50, DST142, and DST 144 was significantly higher (p ≤ 0.05) than DST62. DST62 and DST124 were isolated only from diseased camels. DST62 was isolated only from mastitic milk. DST124 was isolated only from infertile female genitalia. The percentage of DST50 and DST 142 was significantly higher in diseased camels (infertile females) than in the apparently healthy ones (fertile females). DST2 and DST50 were isolated only from female genitalia of apparent health and diseased camels. The C. albicans isolated from diseased camels had significantly higher biofilm formation, hydrophobicity, phospholipase, proteinase, and hemolysin activities compared with the isolates from apparent healthy camels. All isolates were sensitive to amphotericin B, itraconazole, micafungin, posaconazole and voriconazole. In conclusion, the present study represents the first molecular typing of C. albicans in samples isolated from milk and the genital tract of the dromedary camel. MLST is a useful tool for studying the epidemiology and evolution of C. albicans. Early identification of Candida species and attention to Candida virulence factors and their antifungal susceptibility patterns is very important for establishing strategies to control and/or prevent candidiasis by novel therapeutic management. Amphotericin B, itraconazole, micafungin, posaconazole, or voriconazole can be efficient in treatment of candidiasis.

Heme Oxygenase-1 (HMX1) Loss of Function Increases the In-Host Fitness of the Saccharomyces 'boulardii' Probiotic Yeast in a Mouse Fungemia Model

The use of yeast-containing probiotics is on the rise; however, these products occasionally cause fungal infections and possibly even fungemia among susceptible probiotic-treated patients. The incidence of such cases is probably underestimated, which is why it is important to delve deeper into the pathomechanism and the adaptive features of S. ‘boulardii’. Here in this study, the potential role of the gene heme oxygenase-1 (HMX1) in probiotic yeast bloodstream-derived infections was studied by generating marker-free HMX1 deletion mutants with CRISPR/Cas9 technology from both commercial and clinical S. ‘boulardii’ isolates. The six commercial and clinical yeasts used here represented closely related but different genetic backgrounds as revealed by comparative genomic analysis. We compared the wild-type isolates against deletion mutants for their tolerance of iron starvation, hemolytic activity, as well as kidney burden in immunosuppressed BALB/c mice after lateral tail vein injection. Our results reveal that the lack of HMX1 in S. ‘boulardii’ significantly (p < 0.0001) increases the kidney burden of the mice in most genetic backgrounds, while at the same time causes decreased growth in iron-deprived media in vitro. These findings indicate that even a single-gene loss-of-function mutation can, surprisingly, cause elevated fitness in the host during an opportunistic systemic infection. Our findings indicate that the safety assessment of S. ‘boulardii’ strains should not only take strain-to-strain variation into account, but also avoid extrapolating in vitro results to in vivo virulence factor determination.

Efficacy of Syzygium aromaticum essential oil on the growth and enzymatic activity of pathogenic Candida albicans strains

BACKGROUND AND PURPOSE

Candida albicans (C. albicans) is the most common human pathogen owing to the most virulence factors. It seems that extracellular hydrolytic enzymes play a key role in C. albicans pathogenicity. The present study aimed to assess the susceptibility and enzymatic activity of pathogenic C. albicans isolates exposed to the Syzygium aromaticum (S. aromaticum) essential oil.

MATERIALS AND METHODS

S. aromaticum oil was characterized using gas chromatography-mass spectrometry (GC-MS). The broth microdilution technique (CLSI, M27-A3) was used to determine the minimum inhibitory concentration (MIC) of test compounds. Furthermore, before and after treatment with S. aromaticum essential oil, the yeasts were analyzed regarding the proteinase (Prz), hemolysin (Hz), and phospholipase (Phz) production/activity.

RESULTS

β-caryophyllene (12.76%) was found to be the major constituent in the essential oil after eugenol (84.64%). Only one isolate of C. albicans showed the antifungal resistance to fluconazole. All isolates were susceptible to S. aromaticum essential oil with MIC of 625-1250 μg/ml. S. aromaticum oil represented the best antifungal effect against C. albicans at MIC 1000 μg/ml. The mean±SD enzyme activity of C. albicans not exposed to S. aromaticum essential oil was obtained at 0.55±0.03, 0.73±0.04, and 0.61±0.05 for proteinase, hemolysin, and phospholipase, respectively. The activities of these enzymes were reduced significantly (P<0.05) to 0.33±0.06, 0.40±0.04, and 0.16±0.03 for phospholipase, proteinase, and hemolysin, respectively, after the yeasts were subjected to S. aromaticum essential oil.

CONCLUSION

The present study aimed to determine the ability of S. aromaticum essential oil to prevent the growth of C. albicans and decrease their enzymatic activity. As a natural antifungal agent, S. aromaticum can be utilized in pharmaceutical systems.

Comparison of proteinase activity, hemolysin production, and adherence ability of Candida albicans isolates obtained from gastroesophageal lesions and urinary tract infections

Background:

Adhesion of Candida to host cell receptors, hemolysin production, and proteinase activity are assumed as principal virulence factors and infection establishment. These virulence factors are essential for colonization, biofilm formation, and attack on the host cells.

Materials and Methods:

A total of 97 Candida albicans isolates obtained from gastroesophageal lesions and urinary tract infections were included in the study. Adhesion assay, proteinase activity, and hemolysin production were measured. Statistical analysis was performed using the independent t-test and Chi-square test to compare quantitative and qualitative data between the two groups.

Results:

The adherence ability to the buccal epithelial cells was the same in the two groups. Proteinase activity was seen in all clinical isolates. Hemolytic activities were not statistically significant in the two groups.

Conclusion:

Our results recommend that the pathogenicity of C. albicans in the mucous membranes cannot be connected to the infected site.

Candiduria-Study of Virulence Factors and Its Antifungal Susceptibility Pattern in Tertiary Care Hospital

Background The increased incidence of candiduria in hospitalized patients is due to the use of indwelling devices, long-term antibiotics, parenteral nutrition, and immunocompromised status of the patient. In this study, an attempt was made to speciate, characterize, and determine the antifungal susceptibility pattern of Candida isolated from urinary tract infections (UTIs).

Materials and Methods A total of 70 Candida isolates were obtained from urine samples. The isolated Candida species were studied for the production of virulence factors like phospholipase, protease activities, hemolysin, and biofilm production. Antifungal susceptibility testing of the isolated yeasts was done using Mueller-Hinton agar supplemented with 0.5 mg/mL methylene blue by E-test method for amphotericin B, fluconazole, caspofungin, and voriconazole.

Results Out of 70 isolates, Candida tropicalis was the most frequently isolated species (65.7%), followed by Candida albicans (14.3%), Candida glabrata (7.1%), Candida krusei (5.7%), Candida parapsilosis (4.3%), and Candida dubliniensis (2.9%). A total of 37.1% were biofilm producers, 62.9% showed proteinase activity, 38.6% were phospholipase positive, and 58.6% isolates showed hemolytic activity. Antifungal susceptibility profile of Candida species showed 38.6, 25.7, 15.7, and 12.9% resistance to amphotericin B, fluconazole, caspofungin, and voriconazole, respectively.

Conclusion A rising trend in isolation of non-albicans Candida from urinary isolates was noticed, which was statistically significant when comparing catheterized and noncatheterized urinary isolates from our study. However, there was no statistically significant difference when different virulence factor expressions were compared among Candida spp. isolated from catheterized and noncatheterized urinary samples. Due to this rise in non-albicans Candida species causing UTI that are intrinsically resistant to certain antifungal agents like azoles and increasing incidence of antifungal resistance, it is essential to monitor the antifungal susceptibility profile of Candida species causing candiduria.

Virulence Factors and Azole-Resistant Mechanism of Candida Tropicalis Isolated from Candidemia

BACKGROUND

Limited knowledge exists on the virulence factors of Candida tropicalis and the mechanisms of azole resistance that lead to an intensified pathogenicity and treatment failure. We aimed to evaluate the virulence factors and molecular mechanisms of azole resistance among C. tropicalis isolated from patients with candidemia.

MATERIALS AND METHODS

Several virulence factors, including extracellular enzymatic activities, cell surface hydrophobicity (CSH), and biofilm formation, were evaluated. Antifungal susceptibility pattern and expression level of ERG11, UPC2, MDR1, and CDR1 genes of eight (4 fluconazole resistance and 4 fluconazole susceptible) clinical C. tropicalis isolates were assessed. The correlation between the virulence factors and antifungal susceptibility patterns was analyzed.

RESULTS

During a 4 year study, forty-five C. tropicalis isolates were recovered from candidemia patients. The isolates expressed different frequencies of virulence determinants as follows: coagulase 4 (8.9%), phospholipase 5 (11.1%), proteinase 31 (68.9%), esterase 43 (95.6%), hemolysin 44 (97.8%), biofilm formation 45 (100%) and CSH 45(100%). All the isolates were susceptible to amphotericin B and showed the highest resistance to voriconazole. There was a significant positive correlation between micafungin minimum inhibitory concentrations (MICs) and hemolysin production (r_s = 0.316). However, we found a negative correlation between fluconazole MICs and esterase production (r_s = -0.383). We observed the high expression of ERG11 and UPC2 genes in fluconazole-resistant C. tropicalis isolates.

CONCLUSION

C. tropicalis isolated from candidemia patients extensively displayed capacities for biofilm formation, hemolysis, esterase activity, and hydrophobicity. In addition, the overexpression of ERG11 and UPC2 genes was considered one of the possible mechanisms of azole resistance.

Potential Pathogenicity of Candida Species Isolated from Oral Cavity of Patients with Diabetes Mellitus

INTRODUCTION

In the recent decade, the increased immunocompromised population such as diabetic patients makes a high incidence of invasive Candida infections. Diabetes mellitus is the most common endocrine metabolic disorder, and diabetic patients are more susceptible to oral candidiasis infection. Candidiasis is an opportunistic fungal infection caused by many species of Candida. Secretion of exoenzymes plays an important role in the virulence and pathogenesis of Candida species. The aim of this study was to evaluate the potential role of phospholipase, esterase, and hemolytic activity of Candida species isolated from oral cavity lesions of diabetic patients.

METHODS

A total of 108 Candida species including 75 Candida albicans and 33 non-Candida albicans species were recovered from the oral cavity of diabetic patients included in our study. Egg yolk agar, Tween 80 opacity medium, and blood agar plate assays were used for determining phospholipase, esterase, and hemolytic activities, respectively.

RESULTS

Candida albicans species had the most exoenzyme activity in comparison to non-albicans isolates. Candida albicans isolates showed 97.3%, 100%, and 77.3% phospholipase, hemolysin, and esterase activities, respectively. The difference between Candida albicans and non-Candida albicans was significant in phospholipase (P < 0.001) and hemolytic activity (P = 0.027), but not significant in esterase activity (P = 0.076).

CONCLUSION

This study showed that most of the isolates had different enzymatic patterns, and Candida albicans isolates had the most exoenzyme activity. So due to the potential effects of these enzymes in pathogenesis and virulence effects of Candida species, we can conclude that the severity of extracellular enzymes may play a role in the severity of signs and symptoms of Candida oral cavity infections in diabetic patients.

Pathogenicity Assessment of Colombian Strains of Candida auris in the Galleria mellonella Invertebrate Model

Candida auris, first described in 2009, is an opportunistic pathogenic yeast that causes nosocomial outbreaks around the world, with high mortality rates associated with therapeutic failure. In this study, we evaluated the pathogenicity of 107 isolates from two cities in Colombia, associated with fungemia or colonization processes; to achieve this, we used the Galleria mellonella invertebrate model to compare pathogenicity. Our results showed that less than half of the total isolates of C. auris presented a high pathogenicity compared to the reference strain SC5314, and most of those highly pathogenic strains were from colonization processes. We observed that there was formation of large aggregates of cells that cannot be disrupted easily, without statistically significant differences between the pathogenicity of the aggregated and non-aggregated strains. In addition, protease activity was observed in 100% of the C. auris strains; phospholipase and hemolysin activity were observed in 67.3 and 68.2% of the studied strains, respectively. In conclusion, these results highlight the utility of determining survival using G. mellonella, which allowed us to provide new information on the pathogenicity, enzymatic activity, and the relationship of the aggregated and non-aggregated phenotypes of C. auris in this model.

Virulence Factors and Antifungal Susceptibility Profile of C. tropicalis Isolated from Various Clinical Specimens in Alexandria, Egypt

BACKGROUND

The incidence of candidiasis caused by non-albicans Candida (NAC) species is increasing. Candida tropicalis has emerged as one of the most important NAC species. This study aims to examine the antifungal susceptibility profile and some virulence factors of C. tropicalis isolated from various clinical specimens.

METHODS

A total of 71 C. tropicalis isolates from various clinical specimens (69.01%, 18.31%, 9.86%, and 2.82% of isolates were collected from urine, respiratory samples, blood, and skin and soft tissue infections, respectively) from ICU patients in Alexandria, Egypt. The isolates were identified at species level by CHROMagar Candida and VITEK 2 compact system. Furthermore, the antifungal susceptibility was determined using the VITEK 2 system AST-YS07 card containing different antifungals. Hemolysin, phospholipase, and proteinase activity and biofilm formation were also tested as virulence factors.

RESULTS

Only 30 isolates (42.25%) were non-susceptible (MIC ≥ 4 µg/mL) to fluconazole, of which 28 isolates showed non-susceptibility (MIC ≥ 0.25 µg/mL) to voriconazole. All isolates showed both hemolysin and proteinase activities, while only 9 isolates (12.68%) showed phospholipase production and 70 isolates (98.59%) demonstrated biofilm formation. Strong biofilm production was observed among the blood culture isolates (85.71%), followed by the respiratory and urinary isolates (61.54% and 46.94%, respectively).

CONCLUSIONS

This study sought to provide useful data on the antifungal susceptibility of C. tropicalis isolates from ICU patients suffering from invasive infections with an increased trend towards elevated MICs levels of both fluconazole and voriconazole. Due to the high incidence of systemic candidiasis and antifungal resistance, C. tropicalis is emerging as a serious root of infections. Therefore, early and accurate identification of Candida species along with susceptibility testing is of utmost importance.

Cation Transporters of Candida albicans-New Targets to Fight Candidiasis?

Candidiasis is the wide-spread fungal infection caused by numerous strains of yeast, with the prevalence of Candida albicans. The current treatment of candidiasis is becoming rather ineffective and costly owing to the emergence of resistant strains; hence, the exploration of new possible drug targets is necessary. The most promising route is the development of novel antibiotics targeting this pathogen. In this review, we summarize such candidates found in C. albicans and those involved in the transport of (metal) cations, as the latter are essential for numerous processes within the cell; hence, disruption of their fluxes can be fatal for C. albicans.

Virulence of Candida auris from different clinical origins in Caenorhabditis elegans and Galleria mellonella host models

Candida auris is an emerging multidrug-resistant fungal pathogen responsible for nosocomial outbreaks of invasive candidiasis. Although several studies on the pathogenicity of this species have been reported, the knowledge on C. auris virulence is still limited. This study aims to analyze the pathogenicity of C. auris, using one aggregating isolate and eleven non-aggregating isolates from different clinical origins (blood, urine and oropharyngeal specimens) in two alternative host models of candidiasis: Caenorhabditis elegans and Galleria mellonella. Furthermore, possible associations between virulence, aggregation, biofilm-forming capacity, and clinical origin were assessed. The aggregating phenotype isolate was less virulent in both in vivo invertebrate infection models than non-aggregating isolates but showed higher capacity to form biofilms. Blood isolates were significantly more virulent than those isolated from urine and respiratory specimens in the G. mellonella model of candidiasis. We conclude that both models of candidiasis present pros and cons but prove useful to evaluate the virulence of C. auris in vivo. Both models also evidence the heterogeneity in virulence that this species can develop, which may be influenced by the aggregative phenotype and clinical origin.

Back to Nature: Combating Candida albicans Biofilm, Phospholipase and Hemolysin Using Plant Essential Oils

Candida albicans is the causative agent of fatal systemic candidiasis. Due to limitations of antifungals, new drugs are needed. The anti-virulence effect of plant essential oils (EOs) was evaluated against clinical C. albicans isolates including cinnamon, clove, jasmine and rosemary oils. Biofilm, phospholipase and hemolysin were assessed phenotypically. EOs were evaluated for their anti-virulence activity using phenotypic methods as well as scanning electron microscopy (SEM) and atomic force microscopy (AFM). Among the C. albicans isolates, biofilm, phospholipase and hemolysins were detected in 40.4, 86.5 and 78.8% of isolates, respectively. Jasmine oil showed the highest anti-biofilm activity followed by cinnamon, clove and rosemary oils. SEM and AFM analysis showed reduced adherence and roughness in the presence of EOs. For phospholipase, rosemary oil was the most inhibitory, followed by jasmine, cinnamon and clove oils, and for hemolysins, cinnamon had the highest inhibition followed by jasmine, rosemary and clove oils. A molecular docking study revealed major EO constituents as promising inhibitors of the Als3 adhesive protein, with the highest binding for eugenol, followed by 1,8-cineole, 2-phenylthiolane and cinnamaldehyde. In conclusion, EOs have a promising inhibitory impact on Candida biofilm, phospholipase and hemolysin production, hence EOs could be used as potential antifungals that impact virulence factors.

High detection of virulence factors by Candida species isolated from bloodstream of patients with candidemia

OBJECTIVE

Candida species are the normal inhabitants of the skin and mucosa that cause a wide range of debilitating diseases in immunocompromised patients and other susceptible individuals. The present study aimed to evaluate the production of exoenzymes and the biofilm formation capacity of Candida species isolated from candidemia.

MATERIALS AND METHODS

In this study, a total of 100 stock Candida species isolates consist of 50 Candida albicans and 50 non-Candida albicans Candida species (24 C. glabrata, 15 C. parapsilosis, 5 C. dubliniensis, 3 C. tropicalis, 2 C. krusei and 1 C. fabianii) which previously were recovered from patients with candidemia were used. The enzymatic activity tests for hemolysin, proteinase, and phospholipase were performed by using blood Sabouraud dextrose agar, bovine serum albumin medium and egg yolk agar, respectively. Biofilm formation was determined by microplate assay method.

RESULT

All of the Candida albicans species could produce hemolysin. The predominant enzyme activity of species included strong and very strong levels of phospholipase, proteinase and hemolysin activity were belonged to Candida albicans isolates. There were statistically significant differences in hemolysin (P < 0.001), proteinase (P = 0.003) and phospholipase (P < 0.001) activity between two groups of albicans and non-albicans species. The biofilm formation was seen in 30 (60%) of C. albicans and 49 (98%) of non-C. albicans species. There was significant statistical differences between the two groups of isolates in biofilm formation (P < 0.001).

CONCLUSION

It is clear that Candida species have ability to produce several enzymes as virulence factors to contribute its pathogenicity. There were significant differences in virulence factors between the two C. albicans and non- C. albicans group. The ability for biofilm formation and producing exo-enzyme were an important virulence factors in Candida species isolates. This differences found in this report might have role in severity of disease caused by different species.

Caenorhabditis elegans as a Model System To Assess Candida glabrata, Candida nivariensis, and Candida bracarensis Virulence and Antifungal Efficacy

Although Candida albicans remains the major etiological agent of invasive candidiasis, Candida glabrata and other emerging species of Candida are increasingly isolated. This species is the second most prevalent cause of candidiasis in many regions of the world. However, clinical isolates of Candida nivariensis and Candida bracarensis can be misidentified and are underdiagnosed due to phenotypic traits shared with C. glabrata Little is known about the two cryptic species. Therefore, pathogenesis studies are needed to understand their virulence traits and their susceptibility to antifungal drugs. The susceptibility of Caenorhabditis elegans to different Candida species makes this nematode an excellent model for assessing host-fungus interactions. We evaluated the usefulness of C. elegans as a nonconventional host model to analyze the virulence of C. glabrata, C. nivariensis, and C. bracarensis The three species caused candidiasis, and the highest virulence of C. glabrata was confirmed. Furthermore, we determined the efficacy of current antifungal drugs against the infection caused by these species in the C. elegans model. Amphotericin B and azoles showed the highest activity against C. glabrata and C. bracarensis infections, while echinocandins were more active for treating those caused by C. nivariensis C. elegans proved to be a useful model system for assessing the pathogenicity of these closely related species.

Are Candida albicans isolates from the oral cavity of HIV-infected patients more virulent than from non-HIV-infected patients? Systematic review and meta-analysis

Candida albicans is the main causative agent of oral lesions in HIV-infected patients and its oral colonization is a potential source of systemic dissemination. Although the high prevalence of lesions in HIV patients can be explained by the immunosuppressive condition, several studies have reported that natural selection can make C. albicans more virulent in this group of patients. Comparisons of the activity of exoenzymes (phospholipase, proteinase and hemolysin) in C. albicans isolated from HIV-infected and uninfected patients have yielded conflicting results. This study aimed, through a systematic review and meta-analysis, to answer the question: "Is the hydrolytic enzymatic activity of C. albicans, isolated from the oral cavity, different in individuals infected and not infected with HIV?" The question was addressed using the PECO framework: P (Population): children and adults, E (Exposure): HIV infection, C (Comparator): non-HIV-infected patients; O (Outcomes): exoenzymes activity i.e. phospholipase, proteinase and hemolysin. We conducted a systematic search on Pubmed, Embase, Scopus, Livivo, Lilacs, Web of Science, and Science Direct databases, and Google Scholar. The MAStARI tool was used to evaluate the risk of bias in the selected studies. From 2259 studies, 19 were included in this review and 11 comprised the meta-analysis. The activity of phospholipase (M-H = 0.15; Z = 2,76; p = 0.0006) and hemolysin exoenzymes (M-H = 0.07; z = 1,94; p = 0.05) was higher in C. albicans isolated from the oral cavity of HIV-infected patients, whereas the levels of protease activity were not different compared with non-HIV-infected individuals. This study showed a higher phospholipase and hemolysin activity in C. albicans isolates from the oral cavity of HIV-infected patients.

In vitro antifungal activity of Cinnamomum zeylanicum bark and leaf essential oils against Candida albicans and Candida auris

Candida infections are a significant source of patient morbidity and mortality. Candida albicans is the most common pathogen causing Candida infections. Candida auris is a newly described pathogen that is associated with multi-drug-resistant candidiasis and candidaemia in humans. The antifungal effects of various essential oils and plant compounds have been demonstrated against human pathogenic fungi. In this study, the effect of cinnamon leaf and bark essential oils (CEOs) was determined against both C. albicans and C. auris. The disc diffusion (direct and vapour) and broth microdilution method was used to determine antifungal activity of the EOs against selected strains (C. albicans ATCC 10231, C. albicans ATCC 2091 and C. auris NCPF 8971) whilst the mode of action and haemolysin activity of the CEOs were determined using electron microscopy and light microscopy. Direct and vapour diffusion assays showed greater inhibitory activity of bark CEO in comparison with leaf CEO. The minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) of bark CEO for all tested strains was below 0.03% (v/v), which was lower than the MICs of the leaf CEO (0.06–0.13%, v/v) dependent on the strain and the MFCs at 0.25% (v/v). In the morphological interference assays, damage to the cell membrane was observed and both CEOs inhibited hyphae formation. The haemolysin production assay showed that CEOs can reduce the haemolytic activity in the tested C. albicans and C. auris strains. At low concentrations, CEOs have potent antifungal and antihaemolytic activities in vitro against C. albicans and C. auris.

Key points

• Essential oils from Cinnamomum zeylanicum Blume bark and leaf (CBEO and CLEO) demonstrated fungicidal properties at very low concentrations.

• The antifungal activity of CBEO was greater than that of CLEO consistent with other recent published literature.

• The mode of action of CBEO and CLEO was damage to the membrane of C. albicans and C. auris.

• Both CBEO and CLEO inhibited the formation of hyphae and reduced haemolysin production in C. albicans and C. auris.

Human Serum Albumin Facilitates Heme-Iron Utilization by Fungi

Heme constitutes a major iron source for microorganisms and particularly for pathogenic microbes; to overcome the iron scarcity in the animal host, many pathogenic bacteria and fungi have developed systems to extract and take up heme from host proteins such as hemoglobin. Microbial heme uptake mechanisms are usually studied using growth media containing free heme or hemoglobin as a sole iron source. However, the animal host contains heme-scavenging proteins that could prevent this uptake. In the human host in particular, the most abundant serum heme-binding protein is albumin. Surprisingly, however, we found that in the case of fungi of the Candida species family, albumin promoted rather than prevented heme utilization. Albumin thus constitutes a human-specific factor that can affect heme-iron utilization and could serve as target for preventing heme-iron utilization by fungal pathogens. As a proof of principle, we identify two drugs that can inhibit albumin-stimulated heme utilization.

A large portion of biological iron is found in the form of an iron-protoporphyrin IX complex, or heme. In the human host environment, which is exceptionally poor in free iron, heme iron, particularly from hemoglobin, constitutes a major source of iron for invading microbial pathogens. Several fungi were shown to utilize free heme, and Candida albicans, a major opportunistic pathogen, is able both to capture free heme and to extract heme from hemoglobin using a network of extracellular hemophores. Human serum albumin (HSA) is the most abundant host heme-scavenging protein. Tight binding of heme by HSA restricts its toxic chemical reactivity and could diminish its availability as an iron source for pathogenic microbes. We found, however, that rather than inhibiting heme utilization, HSA greatly increases availability of heme as an iron source for C. albicans and other fungi. In contrast, hemopexin, a low-abundance but high-affinity heme-scavenging serum protein, does inhibit heme utilization by C. albicans. However, inhibition by hemopexin is mitigated in the presence of HSA. Utilization of albumin-bound heme requires the same hemophore cascade as that which mediates hemoglobin-iron utilization. Accordingly, we found that the C. albicans hemophores are able to extract heme bound to HSA in vitro. Since many common drugs are known to bind to HSA, we tested whether they could interfere with heme-iron utilization. We show that utilization of albumin-bound heme by C. albicans can be inhibited by the anti-inflammatory drugs naproxen and salicylic acid.

Relationship between antifungal susceptibility profile and virulence factors in Candida albicans isolated from nail specimens

INTRODUCTION

The aim of this study was to evaluate some virulence factors in Candida albicans isolates from patients with onychomycosis and determine the correlation between these factors and the antifungal resistance profile.

METHODS

Seventy species of C. albicans were confirmed using polymerase chain reaction amplification of the HWP1 gene. According to the Clinical & Laboratory Standards Institute guidelines, the susceptibility profile of four antifungal agents was investigated, and the production of aspartyl protease, phospholipase, haemolysin, and biofilm was determined. The correlation between these profiles was also investigated.

RESULTS

The isolates indicated different levels of resistance and production of virulence factors. Significant correlations were observed between the minimum inhibitory concentration (MIC) of fluconazole/itraconazole and biofilm production, between phospholipase production and fluconazole/itraconazole MIC, and between fluconazole MIC and hemolytic activity in C. albicans isolates. The results also showed significant correlations between phospholipase activity and biofilm production.

CONCLUSIONS

Our findings will contribute to a better understanding of the pathogenesis of C. albicans and characterize the relationship between virulence factors and antifungal resistance, which may suggest new therapeutic strategies considering the possible involvement of the virulence mechanism in the effectiveness of treatment.

The adaptive response to iron involves changes in energetic strategies in the pathogen Candida albicans

Candida albicans is an opportunist pathogen responsible for a large spectrum of infections, from superficial mycosis to systemic diseases known as candidiasis. Its ability to grow in different morphological forms, such as yeasts or filamentous hyphae, contributes to its survival in diverse microenvironments. Iron uptake has been associated with virulence, and C. albicans has developed elaborate strategies for acquiring iron from its host. In this work, we analyze the metabolic changes in response to changes in iron content in the growth medium and compare C. albicans adaptation to the presence or absence of iron. Functional and morphological studies, correlated to a quantitative proteomic analysis, were performed to assess the specific pathways underlying the response to iron, both in the yeast and filamentous forms. Overall, the results show that the adaptive response to iron is associated with a metabolic remodeling affecting the energetic pathways of the pathogen. This includes changes in the thiol-dependent redox status, the activity of key mitochondrial enzymes and the respiratory chain. Iron deficiency stimulates bioenergetic pathways, whereas iron-rich condition is associated with greater biosynthetic needs, particularly in filamentous forms. Moreover, we found that C. albicans yeast cells have an extraordinary capability to adapt to changes in environmental conditions.

Impact of Cigarette Smoke Condensate on Adhesion-Related Traits and Hemolysin Production of Oral Candida dubliniensis Isolates

BACKGROUND

Cigarette smoke is associated with higher oral Candida carriage and possible predisposition and increased susceptibility to oral candidal infection. Candida dubliniensis is associated with oral candidosis. Candidal adherence to buccal epithelial cells (BEC) and denture acrylic surfaces (DAS), germ tube (GT) formation, cell surface hydrophobicity (CSH) and hemolysin production are pathogenic traits of Candida.

OBJECTIVES

The impact of exposure to cigarette smoke on the aforementioned pathogenic attributes of oral C. dubliniensis has not been studied. Hence, the impact of cigarette smoke condensate (CSC) on adhesion to BEC and DAS, GT formation, CSH and hemolysin production of 20 oral C. dubliniensis isolates after exposure to CSC for 24, 48 and 72 h was ascertained.

METHODS

After preparation of the CSC, using an in-house smoking device, the Candida isolates were exposed to the CSC for 24, 48 and 72 h, by a previously described in vitro method. Thereafter, the adhesion to BEC and DAS, GT formation, CSH and hemolysin production of C. dubliniensis isolates was investigated by hitherto described in vitro assays.

RESULTS

Exposure to CSC significantly increased the ability of C. dubliniensis oral isolates to adhere to BEC, DAS, GT formation, CSH and produce hemolysin following 24-h, 48-h and 72-h exposure periods to CSC (P < 0.001 for all attributes tested).

CONCLUSIONS

Exposure of oral C. dubliniensis isolates to CSC may significantly promote in vitro adhesion traits and hemolysin production of these isolates, thereby augmenting its pathogenicity in vitro in the presence of cigarette smoke.

Selection of Native Non-Saccharomyces Yeasts with Biocontrol Activity against Spoilage Yeasts in Order to Produce Healthy Regional Wines

Two major spoilage yeasts in the wine industry, Brettanomyces bruxellensis and Zygosaccharomyces rouxii, produce off-flavors and gas, causing considerable economic losses. Traditionally, SO2 has been used in winemaking to prevent spoilage, but strict regulations are in place regarding its use due to its toxic and allergenic effects. To reduce its usage researchers have been searching for alternative techniques. One alternative is biocontrol, which can be used either independently or in a complementary way to chemical control (SO2). The present study analyzed 122 native non-Saccharomyces yeasts for their biocontrol activity and their ability to be employed under fermentation conditions, as well as certain enological traits. After the native non-Saccharomyces yeasts were assayed for their biocontrol activity, 10 biocontroller yeasts were selected and assayed for their ability to prevail in the fermentation medium, as well as with respect to their corresponding positive/negative contribution to the wine. Two yeasts that satisfy these characteristics were Wickerhamomyces anomalus BWa156 and Metschnikowia pulcherrima BMp29, which were selected for further research in application to mixed fermentations.

Candida albicans Interactions with Mucosal Surfaces during Health and Disease

Flexible adaptation to the host environment is a critical trait that underpins the success of numerous microbes. The polymorphic fungus Candida albicans has evolved to persist in the numerous challenging niches of the human body. The interaction of C. albicans with a mucosal surface is an essential prerequisite for fungal colonisation and epitomises the complex interface between microbe and host. C. albicans exhibits numerous adaptations to a healthy host that permit commensal colonisation of mucosal surfaces without provoking an overt immune response that may lead to clearance. Conversely, fungal adaptation to impaired immune fitness at mucosal surfaces enables pathogenic infiltration into underlying tissues, often with devastating consequences. This review will summarise our current understanding of the complex interactions that occur between C. albicans and the mucosal surfaces of the human body.

Changing virulence factors among vaginal non-albicans Candida species

Background

Vulvovaginal candidiasis (VVC) is caused by overgrowth of Candida species in the female lower genital tract and most commonly caused by Candida albicans. The production of various virulence factors may attribute to their pathogenicity. Hence, this study was aimed to determine the production of various virulence factors of Candida spp. causing VVC.

Materials and Methods

A total of 51 Candida spp. were isolated prospectively from 50 patients among 211 clinically suspected cases of VVC. The haemolytic activity, biofilm production, proteinase activity, phospholipase activity and esterase activity were detected by standard methods. Statistical analysis was performed using OpenEpi version 3.01.

Results

Haemolytic activity was observed in 42 Candida isolates (82.4%), biofilm activity in 21 Candida isolates (41.2%), proteinase and esterase activity in 19 Candida isolates (37.3%) each and phospholipase activity in 15 Candida isolates (29.4%). Phospholipase activity was observed in all of the C. albicans strains, whereas all strains of Candida krusei were able to produce biofilm. All strains of Candida parapsilosis and 87% strains of Candida glabrata were haemolytic. Five of the eight C. glabrata strains were found to produce strong proteinase (Pr_z score ≤0.63). About 30.4% strains of C. glabrata and 20% strains of C. krusei were found to be positive for esterase activity. This is one of the few studies which revealed esterase activity among C. glabrata and C. krusei strains.

Conclusions

This study highlighted that there is a change in the virulence factors among the non-albicans Candida species, especially C. glabrata strains which were haemolytic and produce strong proteinase activity and esterase activity. It may be one of the explanation of the most common causative agent of VVC in our study. Multicentric studies from this area might be required to get a more generalised conclusion.

Influence of subinhibitory antifungal concentrations on extracellular hydrolases and biofilm production by Candida albicans recovered from Egyptian patients

BACKGROUND

Extracellular hydrolases (phospholipase, aspartyl protease and haemolysin) and biofilm production are considered as major virulence factors of the opportunistic pathogenic fungus Candida albicans. However, the impact of antifungal therapy on such virulence attributes is not well investigated. The common antifungal agents may disturb the production of secreted hydrolases as well as biofilm formation. Accordingly, this study addressed the effect of subinhibitory concentrations (sub-MICs) of selected antifungal agents on some virulence factors of C. albicans clinical isolates.

METHODS

C. albicans isolates (n = 32) were recovered from different clinical samples and their identification was confirmed to the species level. Antifungal susceptibility profiles of isolates were determined against (nystatin, fluconazole and micafungin) and minimum inhibitory concentrations (MICs) were interpreted according to Clinical and Laboratory Standards Institute guidelines. Virulence determinants comprising secreted hydrolases (phospholipase, aspartyl protease and haemolysin) and biofilm formation were investigated in the presence of the sub-MICs of the tested antifungal agents.

RESULTS

Treatment of clinical C. albicans isolates with subinhibitory nystatin, fluconazole and micafungin concentrations significantly decreased production of extracellular hydrolases. Nystatin had the greatest inhibitory effect on phospholipase and aspartyl protease production. However, micafungin showed the highest reducing effect on the hemolytic activity of the treated clinical isolates. Moreover, nystatin and micafungin, but not fluconazole, had a noticeable significant impact on inhibiting biofilm formation of C. albicans clinical isolates.

CONCLUSION

Our findings highlighted the significant influences of commonly prescribed antifungal agents on some virulence factors of C. albicans. Accordingly, antifungal therapy may modulate key virulence attributes of C. albicans.

Candida sp. Infections in Patients with Diabetes Mellitus

Candidiasis has increased substantially worldwide over recent decades and is a significant cause of morbidity and mortality, especially among critically ill patients. Diabetes mellitus (DM) is a metabolic disorder that predisposes individuals to fungal infections, including those related to Candida sp., due to a immunosuppressive effect on the patient. This review aims to discuss the latest studies regarding the occurrence of candidiasis on DM patients and the pathophysiology and etiology associated with these co-morbidities. A comprehensive review of the literature was undertaken. PubMed, Scopus, Elsevier’s ScienceDirect, and Springer’s SpringerLink databases were searched using well-defined search terms. Predefined inclusion and exclusion criteria were applied to classify relevant manuscripts. Results of the review show that DM patients have an increased susceptibility to Candida sp. infections which aggravates in the cases of uncontrolled hyperglycemia. The conclusion is that, for these patients, the hospitalization periods have increased and are commonly associated with the prolonged use of indwelling medical devices, which also increase the costs associated with disease management.

In vitro Post-Antifungal Effect of Posaconazole and Its Impact on Adhesion-Related Traits and Hemolysin Production of Oral Candida dubliniensis Isolates

OBJECTIVE

Candidal adherence to denture acrylic surfaces (DAS) and oral buccal epithelial cells (BEC), formation of candidal germ tubes (GT), candidal cell surface hydrophobicity (CSH), and hemolysin production are important pathogenic traits of Candida. The antifungal drug-induced post-antifungal effect (PAFE) also impacts the virulence of Candida. Candida dubliniensis isolates are associated with the causation of oral candidiasis which could be managed with posaconazole. Thus far there is no evidence on posaconazole-induced PAFE and its impact on adhesion-related attributes and production of hemolysin by C. dubliniensis isolates. Hence, the PAFE, adhesion to DAS and BEC, formation of GT, CSH, and hemolysin production of 20 oral C. dubliniensis isolates after brief exposure to posaconazole was ascertained.

MATERIALS AND METHODS

The PAFE, adherence to DAS and BEC, formation of GT, candidal CSH, and hemolysin production were investigated by hitherto described in vitro assays.

RESULTS

The mean PAFE (h) induced by posaconazole on C. dubliniensis isolates was 1.66. Exposure to posaconazole suppressed the ability of C. dubliniensis to adhere to DAS, BEC, formation of candidal GT, candidal CSH and to produce hemolysin by a reduction of 44, 33, 34, 36, and 15% (p < 0.005 to p < 0.001), respectively.

CONCLUSION

Exposure of C. dubliniensis isolates to posaconazole for a brief period induced an antimycotic impact by subduing its growth in addition to suppressing pathogenic adherence-associated attributes, as well as production of hemolysin.

Phenotypic and genotypic variations in Candida albicans isolates from Romanian patients

Background: During the last two decades a major increase in the proportion of severe fungal infections has been noted due to the excessive use of broad-spectrum antibiotics, catheters, and a growing number of immunocompromised patients.

Objectives: This is the first investigation providing complete data regarding the phenotypic and genotypic profiles of Candida albicans (C. albicans) isolates in Romanian patients.

Methods: We investigated 301 isolates in terms of genotype determination (G), resistogram (R), phospholipase activity (Pl), haemolysis (Hl), proteinase activity (Pt), and biofilm formation (BF).

Results: The analyzed isolates of C. albicans showed low values for Pt (61.73%), Hl (95.49%), and BF (60.71%), and did not present any Pl activity (92.23%). More than half of the investigated samples were genotype A with 450 bp (52.92%) and the majority (86.19%) were resistant to sodium selenite (A), boric acid (B), sodium periodate (D) and silver nitrate (E), but sensitive to cetrimide (-). One-way ANOVA analysis revealed significant effects of the infection site on biofilm formation (p = 0.0137) and no significant correlation was found between the genotype (A, B, C) and the infection site (p =0.449).

Conclusions: Based on the obtained results it can be concluded that C. albicans isolates in Romanian patients exhibit different genotypic and phenotypic patterns, and no significant correlations between genotype and infection site could be observed.

Iron at the Centre of Candida albicans Interactions

Iron is an absolute requirement for both the host and most pathogens alike and is needed for normal cellular growth. The acquisition of iron by biological systems is regulated to circumvent toxicity of iron overload, as well as the growth deficits imposed by iron deficiency. In addition, hosts, such as humans, need to limit the availability of iron to pathogens. However, opportunistic pathogens such as Candida albicans are able to adapt to extremes of iron availability, such as the iron replete environment of the gastrointestinal tract and iron deficiency during systemic infection. C. albicans has developed a complex and effective regulatory circuit for iron acquisition and storage to circumvent iron limitation within the human host. As C. albicans can form complex interactions with both commensal and pathogenic co-inhabitants, it can be speculated that iron may play an important role in these interactions. In this review, we highlight host iron regulation as well as regulation of iron homeostasis in C. albicans. In addition, the review argues for the need for further research into the role of iron in polymicrobial interactions. Lastly, the role of iron in treatment of C. albicans infection is discussed.