Candida Adhesion Research Articles

The high frequency of mecA and Als3p genes among Staphylococcus aureus and Candida species isolated from patients with malignancies on chemotherapy

The present study aimed to survey the prevalence of methicillin-resistant Staphylococcus aureus and Candida species oral and nasal co-colonization among patients with malignancies on chemotherapy in Tehran, Iran. In a cross-sectional single-center study performed from October until the end of December 2020, oral and nasal specimens were collected using dry sponge swabs from patients with different malignancies under chemotherapy in Masih Daneshvari Hospital, Tehran, Iran. We used the disk diffusion method to the screening of oxacillin (methicillin) resistance among S. aureus isolates. The final identification of MRSA strains and the frequency of hyphal adhesin Als3p was performed using the PCR method with a specific primer that targeted mecA and Als3p genes, respectively. A total of 170 oral and nasal specimens were collected from 170 adult patients. Oral colonization by S. aureus, MRSA, and Candida species was found in 20 (11.8%), 11 (6.5%), and 68 (40%) patients, respectively, while nasal colonization by S. aureus and MRSA and Candida species was found in 26 (15.3%), 17 (10%) and 7 (4.1%) patients, respectively. The total colonization of MRSA and Candida spp. in both oral and nasal was 14.7% (n = 25/170) and 41.2% (n = 70/170), respectively. All MRSA isolates and Candida species were positive for mecA and Als3p genes, respectively. The present study revealed the importance of polymicrobial infection among patients with different malignancies and presumed that S. aureus can use Candida adhesion Als3p to create systemic infections in immunocompromised patients.

The Influencing Effect of Silver Nitrate Fillers on the hardness of Flexible Resin

The development of polymer chemically produces alternative materials to polymethyl methacrylate, such as nylon, and epoxy resin, these resins are modified by thermoplastic process, and This Received The disadvantage of acrylic resin is the colonization of microorganism growth of fungi and candida adhesion. This study is designed to evaluate and compared the consequence of silver nitrate fillers reinforcement Accepted flexible acrylic hardness as one of the mechanical properties to find the effect of various concentrations. A (0.1and 0. 2) ml of the filler (silver nitrate) additive to the flexible acrylic. Forty five (45) specimens were prepared for testing in this study. The hardness test was used in this study. The sample of this test was divided into (3) groups (control group) and experimental groups as follows: Group A= (15) specimens without silver nitrate (Control group 0% silver nitrate). Group B= (15) specimens with (0.1 ml) silver nitrate. Group C= (15) specimens with (0.2 ml) silver nitrate. All control and test groups were processed; curred then finished and polished the specimens ready for testing. Shore A test against the concentration of silver nitrate the result of this study showed a high significant increase in the mean value of hardness for control groups to the silver nitrate compared with experimental groups.

Clinical study of risk factors for adherence of Candida to dentures

We aimed to identify the time of adherence, predicting factors, and species of Candida adhering to the mucosal surface of new maxillary dentures fabricated and placed in our department. Three types of oral samples from 32 patients were collected at the time of new denture placement (baseline) and at five follow-up visits (1, 3, 6, 9, and 12 months). Candida adherence, indicated by a positive culture originating from the mucosal surface of the denture base (MSDB) at any time during follow-up, was tested for its associations with several putative predictors. The protocols of a second, additional study were identical to the initial study except that, at each visit, all 22 participants received an educational intervention regarding denture cleaning and maintenance. Of the 14 patients with extensive oral Candida colonization at baseline, 11 already had Candida -positive MSDB swabs at the 1-month follow-up. Candida carriage, xerostomia, and denture cleaning habits were associated with MSDB Candida colonization. In the additional study, when subjects consistently cleaned and maintained their dentures, Candida was detected at a lower rate on the MSDB at follow-up visits after 6 months than that observed in the initial study (18% [4/22] vs. 56% [18/32], p < 0.05). Candida carriage at the time of new denture placement is strongly predictive of subsequent adherence to the MSDB. Regardless of the oral Candida carriage state, patients can limit this colonization by consistently following good cleaning and maintenance habits, starting from the time of new denture placement.

Synergistic Interaction of Piperine and Thymol on Attenuation of the Biofilm Formation, Hyphal Morphogenesis and Phenotypic Switching in Candida albicans.

The incidence of fungal infections has significantly increased in recent years due to the emergence of antifungal resistance. Biofilm formation is considered to be a major contributor to both the infectious diseases and to antimicrobial resistance. Consequently, biofilm-associated infections are often problematic to treat with existing therapeutics. Adhesion of C. albicans to the host surface or implanted materials followed by hyphal invasion and biofilm formation enhances C. albicans pathogenicity and virulence. Thus, developing a therapeutic agent that inhibits candidal adherence, biofilm development and morphological switching could improve clinical management of infections. The present investigation studied two emerging and alternatives strategies, namely antibiofilm and combinatorial approach, to attenuate biofilm formation and the expression of Candida virulence factors. Piperine and thymol are major bioactive components of pepper and thyme, respectively. These phytochemicals are known to possess numerous biological activities, including recently reported antibiofilm effects against C. albicans. The minimum biofilm inhibitory concentration (MBIC) of both phytochemicals was determined to be 32 µg/ml. The phytochemical treatment of Candida biofilms using piperine and thymol revealed synergistic effects at four different combinations of concentrations, i.e. 8 and 8, 8 and 4, 8 and 2 and 4 and 8 µg/ml. These synergistic combinations resulted in the significant reduction in adherence of Candida, hyphal extension and morphological transformation. Moreover, limited exposure of synergistic combinations controlled the hyphal elongation. Results were validated through the gene expression analysis. Results from the present investigation suggest that piperine and thymol can be synergistically employed for the treatment of biofilm-associated C. albicans infection.

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.

Evaluation of the effectiveness of current disinfection methods in complete denture patients.

Candida adherence to the denture base is an important cause of denture stomatitis in elderly and handicapped patients where effective patient- and physician-based disinfection methods are required. The purpose of this study was to investigate the in vivo effectiveness of chemical and physicochemical methods and their combinations against common oral Candida species on denture base acrylic resin. Patients were divided into six groups according to disinfection methods. For chemical disinfection, chlorhexidine, sodium hypochlorite, and glutaraldehyde were used by the patients. Microwave and ozone therapy were applied by physicians for physicochemical disinfection. Fungal load count was performed. This procedure was repeated before applying any disinfection procedures, at 1 week and 1 month after the patient started to use the relevant chemical disinfectant and apply physicochemical methods. A multivariate analysis test was used to determine the change in fungal load over time and whether this change led to a difference among the groups (P < .05). The most frequently isolated Candida strain was Candida albicans. The change in fungal load over time was significantly different (P < .001). However, the difference between the groups did not show any significant difference in the paired comparison analyses of the chemical disinfection groups (P >.05). No Candida strains were detected in either physicochemical method at any of the control time points. The study concluded that chemical disinfectants used by patients were effective for but total eradication of Candida adhesion requires the use of additional ozone or microwave therapy.

Hedera rhombea inhibits the biofilm formation of Candida, thereby increases the susceptibility to antifungal agent, and reduces infection

Candida is an opportunistic pathogen and a common cause of fungal infections worldwide. Anti-fungal use against Candida infections has resulted in the appearance of resistant strains. The limited choice of anti-fungal therapy means alternative strategies are needed to control fungal infectious diseases. The aim of this study was to evaluate the inhibition of Candida biofilm formation by Hedera rhombea (Korean name: songak) extract. Biofilm formation was assessed using the crystal violet assay which showed a dose dependent reduction in the presence of extract with the biofilm formation inhibitory concentration of C. albicans (IC50 = 12.5μg/ml), C. tropicalis var. tropicalis (IC50 = 25μg/ml), C. parapsilosis var. parapsilosis (IC50 = 6.25μg/ml), C. glabrata (IC50 = 6.25μg/ml), C. tropicalis (IC50 = 12.5μg/ml), and C. parapsilosis (IC50 = 12.5μg/ml) without directly reducing Candida growth. Treatment with 6.25μg/mL of extract increased the antifungal susceptibility to miconazole from 32% decreasing of fungal growth to 98.8% of that based on the fungal growth assay. Treatment of extract dose-dependently reduced the dimorphic transition of Candida based on the dimorphic transition assay and treatment of 3.125μg/mL of extract completely blocked the adherence of Candida to the HaCaT cells. To know the molecular mechanisms of biofilm formation inhibition by extract, qRT-PCR analysis was done, and the extract was found to dose dependently reduce the expression of hyphal-associated genes (ALS3, ECE1, HWP1, PGA50, and PBR1), extracellular matrix genes (GSC1, ZAP1, ADH5, and CSH1), Ras1-cAMP-PKA pathway genes (CYR1, EFG1, and RAS1), Cph2-Tec1 pathway gene (TEC1) and MAP kinases pathway gene (HST7). In this study, Hedera rhombea extract showed inhibition of fungal biofilm formation, activation of antifungal susceptibility, and reduction of infection. These results suggest that fungal biofilm formation is good screen for developing the antifungal adjuvant and Hedera rhombea extract should be a good candidate against biofilm-related fungal infection.

Antifungal Activity of Denture Base Resin Containing Nanozirconia: In Vitro Assessment of Candida albicans Biofilm.

Objective To evaluate the antimicrobial effects of different concentrations of zirconium dioxide nanoparticles (nano-ZrO2) reinforcement of poly(methyl) methacrylate (PMMA) on surface roughness and C. albicans biofilm. Methods 20 heat-polymerized acrylic resin discs were conventionally made and divided into 4 groups (n = 5) according to nano-ZrO2 concentration: control (0% filler) and 3 experimental groups (2.5% (Z2.5), 5.0% (Z5.0), and 7.5% (Z7.5)). An optical profilometer was used for surface roughness evaluation, followed by Candida adherence assay. Specimens were sterilized, then immersed in cultured yeast (C. albicans), and incubated at 37°C for 48 hours. After that, discs were rinsed before extracting the clustered pellets of Candida. The attached C. albicans was counted using the direct method after spreading on agar media and incubating for 48 hours. Statistical analysis was performed using one-way ANOVA and Tukey's post hoc test at α = 0.05. Results Surface roughness was significantly increased with all modified groups compared with control (P < 0.01), which showed the lowest roughness value (0.027 ± 0.004 μm). There was no significant difference in the roughness value among reinforced groups (2.5, 5.0, and 7.5%) (P > 0.05), with Z7.5 showing the highest roughness value (0.042 ± 0.004 μm). Candida count was reduced as the nano-ZrO2 increased but not significantly (P=0.15). Conclusions The addition of different concentrations of nano-ZrO2 particles to PMMA increased the surface roughness compared with control; in contrast, insignificant reduction of C. albicans biofilm was detected.

Biologically rapid synthesized silver nanoparticles from aqueous Eucalyptus camaldulensis leaf extract: Effects on hyphal growth, hydrolytic enzymes, and biofilm formation in Candida albicans.

Bionanotechnology has increasingly gained attention in biomedical fields as antifungal and antibiofilm agents. In this study, biosynthesized silver nanoparticles (bio-AgNPs) using aqueous Eucalyptus camaldulensis leaf extract were successfully performed by a one-step green approach. Spherical-shaped nanoparticles, approximately8.65 nm, exhibited noncytotoxicity to erythrocytes, HeLa, and HaCaT cells. The synthesized nanoparticles showed strong fungicidal activity ranging from 0.5 to 1 µg/ml. The nanoparticles affected Candida adhesion and invasion into host cells by reduced germ tube formation and hydrolytic enzyme secretion. Inhibitory effects of bio-AgNPs on Candida biofilms were evaluated by the prevention of yeast-to-hyphal transition. A decrease in cell viability within mature biofilm demonstrated the ability of bio-AgNPs to penetrate into the extracellular matrix and destroy yeast cell morphology, leading to cell death. Molecular biology study on biofilms confirmed downregulation in the expression of genes ALS3, HWP1, ECE1, EFG1, TEC1, ZAP1, encoding hyphal growth and biofilm development and PLB2, LIP9, SAP4, involved in hydrolytic enzymes. In addition to candida treatment, the bio-AgNPs could be applied as an antioxidant to protect against oxidative stress-related human diseases. The findings concluded thatbio-AgNPs could be used as an antifungal agent for candida treatment, as well as be incorporated in medical devices to prevent biofilm formation.

Double-layered acrylic resin denture base with nanoparticle additions: An in vitro study

Statement of problemWhether the addition of different antifungal nanoparticles to denture base materials may affect physical or esthetic properties of the resulting nanocomposite is unclear. PurposeThe purpose of this in vitro study was to determine how a new method of adding antifungal nanofiller affects the properties of the processed nanocomposite denture base material. Material and methodsHeat-polymerized acrylic resin specimens were prepared according to each test specification. Zirconium dioxide nanoparticles (ZrO2NPs) and silver nanoparticles (AgNPs) were added in 0.5, 1.0, and 1.5% of acrylic resin powder. The specimens were divided into 2 groups according to the acrylic resin packing method: 1 layer packed conventionally in one step and 2 layers packed in 2 steps, first with unmodified acrylic resin and then by a thin layer of modified acrylic resin before the final closure. The control group was made of unaltered acrylic resin in 1 step. Flexural strength (FS), translucency, and surface roughness (Ra) were measured. A microbial assay was performed by using the direct culture and slide count methods. Three-way ANOVA and Tukey post hoc tests were used to identify statistical differences among groups (α=.05). ResultsThe addition of ZrO2NPs and AgNPs in the 1- or 2-layer specimens reduced Candida albicans adhesion (P<.001). In the 1- and 2-layer specimens, FS significantly increased with ZrO2NPs. AgNPs decreased FS only in the 1-layer specimen (P<.001). Surface roughness was not changed for the 1- and 2-layer specimens with ZrO2NPs or the 1-layer specimen with 0.5% AgNPs (P>.05), while other AgNP groups exhibited increased surface roughness (P<.001). AgNPs significantly lowered translucency in the 1- and 2-layer specimens (P<.001), while ZrO2NPs decreased translucency only in the 1-layer specimen (P<.001). ConclusionsThe addition of ZrO2NPs in the double-layer technique decreased Candida adhesion and improved FS without affecting surface roughness, while AgNPs decreased Candida adhesion and FS and increased surface roughness. Both nanofillers decreased the translucency except 0.5% ZrO2NPs, which did not change translucency when applied in 2 layers.

Anandamide prevents the adhesion of filamentous Candida albicans to cervical epithelial cells

Candidiasis is a fungal infection caused by Candida species that have formed a biofilm on epithelial linings of the body. The most frequently affected areas include the vagina, oral cavity and the intestine. In severe cases, the fungi penetrate the epithelium and cause systemic infections. One approach to combat candidiasis is to prevent the adhesion of the fungal hyphae to the epithelium. Here we demonstrate that the endocannabinoid anandamide (AEA) and the endocannabinoid-like N-arachidonoyl serine (AraS) strongly prevent the adherence of C. albicans hyphae to cervical epithelial cells, while the endocannabinoid 2-arachidonoylglycerol (2-AG) has only a minor inhibitory effect. In addition, we observed that both AEA and AraS prevent the yeast-hypha transition and perturb hyphal growth. Real-time PCR analysis showed that AEA represses the expression of the HWP1 and ALS3 adhesins involved in Candida adhesion to epithelial cells and the HGC1, RAS1, EFG1 and ZAP1 regulators of hyphal morphogenesis and cell adherence. On the other hand, AEA increased the expression of NRG1, a transcriptional repressor of filamentous growth. Altogether, our data show that AEA and AraS have potential anti-fungal activities by inhibiting hyphal growth and preventing hyphal adherence to epithelial cells.

Effect of &lt;i&gt;Phyllanthus amarus&lt;/i&gt; Coating Denture Resin on Candida Adhesion and its Effect on Human Gingival Fibroblast

Candida infection has become increasingly important as an opportunistic infection frequently found in the oral cavity of denture wearing patients. The infection develops on oral mucous membrane and can spread to other parts of the body. Phyllanthusamarus, extensively grown in many tropical and subtropical countries, has been reported to have various medicinal properties including antimicrobial activity. This study aimed to assess the effect of P.amarus coating denture resin on Candida adhesion and its effect on human gingival fibroblast. The P. amarus coating solution was prepared by water extraction of dried leaves and freeze drying. Denture PMMA resin (SCG Chemical, Thailand) samples were made and coated with various concentrations (0.01-10 mg/mL) of P. amarus solution. Candida adhesion assay was performed on C. albicans ATCC 10231, C. glabrata ATCC 6258, C. krusei ATCC 90030 and C. tropicalis ATCC 13803 based on the method described by Samaranayake and MacFarlane. Cytotoxicity test was done on human gingival fibroblasts (HGF) according to ISO standard 10993-5/2009 for medical product testing. The result showed that P.amarus coating denture resin exhibited an inhibitory effect on the adhesion of all species of test Candida. Cytotoxicity testing revealed a dose-dependent effect of the P. amarus extract on human gingival fibroblast. At the concentrations of 0.1, 1, 5 and 10 mg/mL, the extract produced 84.7%, 73.4%, 64.7% and 38.2% of cell viability, respectively. In conclusion, coating denture resin with P. amarus at a concentration of 1 mg/mL can be used safely as a natural alternative preventive to control or prevent Candida infection caused by C. krusei and C. tropicalis in denture-wearing patients avoiding side effects of chemical antifungal agents. Further studies are needed to define the antifungal components and mechanisms of action as well as clinical trials in the patients.

Biosurfactant from vaginal Lactobacillus crispatus BC1 as a promising agent to interfere with Candida adhesion

BackgroundLactobacillus spp. dominating the vaginal microbiota of healthy women contribute to the prevention of urogenital and sexually transmitted infections. Their protective role in the vagina can be mediated by Lactobacillus cells themselves, metabolites or bacterial components, able to interfere with pathogen adhesion and infectivity. Vulvovaginal candidiasis (VVC) is a common genital infection, caused by the overgrowth of opportunistic Candida spp. including C. albicans, C. glabrata, C. krusei and C. tropicalis. Azole antifungal drugs are not always efficient in resolving VVC and preventing recurrent infections, thus alternative anti-Candida agents based on vaginal probiotics have gained more importance. The present work aims to chemically characterize the biosurfactant (BS) isolated from a vaginal Lactobacillus crispatus strain, L. crispatus BC1, and to investigate its safety and antiadhesive/antimicrobial activity against Candida spp., employing in vitro and in vivo assays.ResultsBS isolated from vaginal L. crispatus BC1 was characterised as non-homogeneous lipopeptide molecules with a critical micellar concentration value of 2 mg/mL, and good emulsification and mucoadhesive properties. At 1.25 mg/mL, the BS was not cytotoxic and reduced Candida strains’ ability to adhere to human cervical epithelial cells, mainly by exclusion mechanism. Moreover, intravaginal (i.va.) inoculation of BS in a murine experimental model was safe and did not perturb vaginal cytology, histology and cultivable vaginal microbiota. In the case of i.va. challenge of mice with C. albicans, BS was able to reduce leukocyte influx.ConclusionsThese results indicate that BS from vaginal L. crispatus BC1 is able to interfere with Candida adhesion in vitro and in vivo, and suggest its potential as a preventive agent to reduce mucosal damage occasioned by Candida during VVC.

A synergistic association between adhesion-related genes and multidrug resistance patterns of Staphylococcus aureus isolates from different patients and healthy individuals

ObjectivesBiofilm -forming capacity of Staphylococcus aureus (S. aureus) as a commensal opportunistic bacterial species induce a growth in antibiotic resistance in chronic diseases. Since expression of biofilm- related genes and antibiotic resistance function are interdependent, the present study was an attempt to inquire biofilm formation and its relationship with antibiotic resistance in clinical isolates. Methods208 S. aureus clinical isolates from four major provinces of Iran were investigated in terms of presence of adhesion genes (icaA, icaD, icaB, icaC, fnbpA, fnbpB, clfA, clfB, cna, sasC, sasG and bap) using PCR. In addition, microtiter plate (Mtp) assay was performed to examine quantitative biofilm formation of the isolates and their antibiotic resistance patterns against 16 antibiotics determined upon CLSI criteria. ResultsThe results revealed high prevalence rate (almost 100%) of icaADBC and MSCRAMMs genes in the isolates. Moreover, bap gene was not detected in any of the tested clinical isolates. Based on phenotypic method 169 isolates (81.25%) were also found to have biofilm formation ability. Among 208 isolates, 98 (47.12%) isolates were multidrug resistant (MDR). Vancomycin, linezolid, nitrofurantoin and quinupristin/dalfopristin were the most effective drugs against MDR strains. Furthermore, the findings demonstrated a significant relationship between MDR and biofilm forming capacity. ConclusionPrevalence rate of adhesion- related genes was high in S. aureus from isolates in Iran ;so these genes might be expressed under certain conditions and cause emergence of MDR strains. Therefore, further investigations are necessary to prevent initial attachment based on new candidate adhesion genes for vaccine design.

Investigating the expression of ALS2 and ALS9 genes along with allele frequency of ALS9 in patients with vulvovaginal candidiasis

BackgroundVulvovaginal candidiasis (VVC) is a vaginal mucosal infection that usually infects women in their reproductive age. When the signs of VVC persist on a daily basis or last for a long time and repeat at least three times per year, the disease is considered chronic and recurrent. ObjectivesThe purpose of this study was to determine the expression rate of 2 genes responsible for adhesion and virulence of candida in RVVC patients using Real-time PCR, and comparing them together and assess the presence or absence of ALS9–2 allele in these patients. Patients/methodsThe vaginal discharge was collected from 120 women aged (22–55) attending lolagar hospital which were all diagnosed with RVVC and 120 age-matched healthy controls. The expression rate of ALS2 and ALS 9 genes was quantified using real-time PCR. PCR method was used for Identification of ALS9 gene alleles. ResultsResults showed an increase in ALS2 gene expression and a decrease in ALS9 gene expression, comparing to basic level and standard sample. 42.5% (51 of total 120 samples) contained the small allele. ConclusionsThe significant difference in expression rates of ALS2 and ALS9 genes indicates their different roles in making morphogenesis changes during the virulence of Candida albicans. Emergence of heterogeneous form and detection of ALS's short allele in invasive form of fungi proves the significant pathogenic role of this allele, specially when attached to mucosal tissue. Invasive and recurrent form of the disease can be accompanied by genetic-morphologic changes in fungi. Considering the form of this disease and the reduction in ALS9 gene expression, it can be concluded that this gene plays a significant role in attachment and initiation of the pathogenic phase.

Antifungal and Antivirulence Activities of Hydroalcoholic Extract and Fractions of Platonia insignis Leaves against Vaginal Isolates of Candida Species.

Vulvovaginal candidiasis is a common fungal infection in women. In this study, Platonia insignis hydroalcoholic extract (PiHE) and its fractions were evaluated for antifungal and antivirulence activities against vaginal Candida species. Dichloromethane (DCMF) and ethyl acetate fractions (EAF) obtained from PiHE effectively inhibited the pathogen. Electrospray ionization mass spectrometry was used for identifying the main compounds in extracts. Minimal inhibitory and fungicidal concentrations (MIC and MFC, respectively) were determined by a broth microdilution assay. Furthermore, we evaluated the effect of the extract and fractions on the virulence properties of Candida albicans, and their cytotoxicity effect was determined on RAW 264.7 cells. Compounds found in extracts were flavonoid glycosides, mainly derivatives of quercetin and myricetin. Extracts showed antifungal potential, with the lowest MIC value for EAF (1.3 mg/mL) and inhibited Candida adherence and biofilm formation. EAF disrupted 48 h biofilms with an inhibition rate of more than 90%. The extract and its fractions exhibited no cytotoxicity. The antifungal effects were attributed to the ability of these extracts to alter the mitochondrial membrane potential for the release of pro-apoptotic factors in the cytosol. In conclusion, our data suggest that PiHE and EAF could act as novel candidates for the development of new therapeutic treatments against fungal infections.

Oral Candidiasis: A Disease of Opportunity

Oral candidiasis, commonly referred to as “thrush,” is an opportunistic fungal infection that commonly affects the oral mucosa. The main causative agent, Candida albicans, is a highly versatile commensal organism that is well adapted to its human host; however, changes in the host microenvironment can promote the transition from one of commensalism to pathogen. This transition is heavily reliant on an impressive repertoire of virulence factors, most notably cell surface adhesins, proteolytic enzymes, morphologic switching, and the development of drug resistance. In the oral cavity, the co-adhesion of C. albicans with bacteria is crucial for its persistence, and a wide range of synergistic interactions with various oral species were described to enhance colonization in the host. As a frequent colonizer of the oral mucosa, the host immune response in the oral cavity is oriented toward a more tolerogenic state and, therefore, local innate immune defenses play a central role in maintaining Candida in its commensal state. Specifically, in addition to preventing Candida adherence to epithelial cells, saliva is enriched with anti-candidal peptides, considered to be part of the host innate immunity. The T helper 17 (Th17)-type adaptive immune response is mainly involved in mucosal host defenses, controlling initial growth of Candida and inhibiting subsequent tissue invasion. Animal models, most notably the mouse model of oropharyngeal candidiasis and the rat model of denture stomatitis, are instrumental in our understanding of Candida virulence factors and the factors leading to host susceptibility to infections. Given the continuing rise in development of resistance to the limited number of traditional antifungal agents, novel therapeutic strategies are directed toward identifying bioactive compounds that target pathogenic mechanisms to prevent C. albicans transition from harmless commensal to pathogen.

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

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. 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 72h was ascertained. After preparation of the CSC, using an in-house smoking device, the Candida isolates were exposed to the CSC for 24, 48 and 72h, 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. 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). 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.

Adherence of local isolates of Candida species to vaginal epithelial cells of apparently healthy and HIV-infected women in Nigeria, and pro-inflammatory cytokines response in a mouse model

Abstract Background Candida albicans (CA) has long been considered as the commonest cause of vulvovaginal candidiasis (VVC), while non-albicans Candida species (NAC) are mainly involved in opportunistic infections, particularly in HIV/AIDS. A prerequisite for colonization and eventual invasion of vaginal mucosa is the ability of Candida to adhere to vaginal epithelial cells (VECs); subsequent production of proinflammatory cytokines, such as IL-1β, IFN-γ, and IL-17, plays key roles in antifungal activity in the mucosa. Recent reports suggest increasing importance of non-albicans Candida species in VVC, in our region. This raised the need to compare the capacity of the local isolates of CA and NAC to adhere to VECs, and to elicit key inflammatory cytokines in mouse model. Materials and Methods Vaginal Epithelial Cells were collected from apparently healthy non-pregnant women, as well as those having HIV infection (n=16). The VECs were exposed to 12 local isolates of CA and NAC, in adherence assay. Mice were intra-vaginally inoculated with the Candida species and assayed for IL-1β, IL-17 and IFN-γ after 14 days. Results More NAC yeasts adhered to VECs of HIV infected women (Mean value = 5.6±3.8) than CA (2.7±3.3). Mean adherence of Candida to VECs from other sources were: HIV infected women with VVC (NAC = 6.2±4.7; CA = 5.1±1.7); apparently healthy women (CA = 2.90±3.40; NAC = 2.8±2.0). Mean levels (ng/ml) of IL-17 produced were: NAC (0.16±0.01) and CA (0.13±0.01). Conclusion Results tend to suggest that NAC is now as important as CA in VVC, and that pre-sensitization of VECs (of HIV+ women) increased Candida adherence. Depletion of IL-17 producing CD4+ cells could partly explain the preponderance of NAC in HIV/AIDS fungal opportunistic infections.

Adherence and Cytotoxicity of Candida spp. to HaCaT and A549 cells.

Candida species are opportunistic fungal pathogens that cause superficial or invasive infections. Recently, the incidence of infection by non-Candida albicans species, especially Candida glabrata, has increased. In this study, we analyzed the adhesion and cytotoxicity of various Candida spp. that are part of the normal human microbiota. C. albicans adheres well to cell culture plates and to cultured cells. C. glabrata selectively adheres to epithelial cells rather than to cell culture plates. Candida parapsilosis insufficiently adheres to confluent monolayers of human lung epithelial A549 and keratinocyte HaCaT cells. We then analyzed the cytotoxicity of C. albicans and C. glabrata, which adhered well to epithelial cells. C. glabrata has been found to cause more damage to A549 cells than to HaCaT cells, suggesting that resident Candida spp. have distinct cytotoxic effects in different tissues. It is important to clarify the properties of Candida spp. as there is evidence that normal microbiota can cause infections. Our data suggest that it is necessary to use appropriate cell lines for characterizing the adherence and cytotoxicity of Candida spp.