Influence of cancer treatment on the Candida albicans isolated from the oral cavities of cancer patients

Candida albicans-A systematic review to inform the World Health Organization Fungal Priority Pathogens List

Candida albicans is a common fungal pathogen and amongst the leading causes of invasive candidiasis globally. This systematic review examines the characteristics and global impact of invasive infections caused by C. albicans. We searched on PubMed and Web of Science for studies reporting on criteria such as mortality, morbidity, drug resistance, preventability, yearly incidence, and distribution/emergence during the period from 2016 to 2021. Our findings indicate that C. albicans is the most common Candida species causing invasive disease and that standard infection control measures are the primary means of prevention. However, we found high rates of mortality associated with infections caused by C. albicans. Furthermore, there is a lack of data on complications and sequelae. Resistance to commonly used antifungals remains rare. Although, whilst generally susceptible to azoles, we found some evidence of increasing resistance, particularly in middle-income settings-notably, data from low-income settings were limited. Candida albicans remains susceptible to echinocandins, amphotericin B, and flucytosine. We observed evidence of a decreasing proportion of infections caused by C. albicans relative to other Candida species, although detailed epidemiological studies are needed to confirm this trend. More robust data on attributable mortality, complications, and sequelae are needed to understand the full extent of the impact of invasive C. albicans infections.

Network Pharmacology, Molecular Docking, and Molecular Dynamics Simulation to Elucidate the Molecular Targets and Potential Mechanism of Phoenix dactylifera (Ajwa Dates) against Candidiasis

Candidiasis, caused by opportunistic fungal pathogens of the Candida genus, poses a significant threat to immunocompromised individuals. Natural compounds derived from medicinal plants have gained attention as potential sources of anti-fungal agents. Ajwa dates (Phoenix dactylifera L.) have been recognized for their diverse phytochemical composition and therapeutic potential. In this study, we employed a multi-faceted approach to explore the anti-candidiasis potential of Ajwa dates' phytochemicals. Utilizing network pharmacology, we constructed an interaction network to elucidate the intricate relationships between Ajwa dates phytoconstituents and the Candida-associated molecular targets of humans. Our analysis revealed key nodes in the network (STAT3, IL-2, PTPRC, STAT1, CASP1, ALB, TP53, TLR4, TNF and PPARG), suggesting the potential modulation of several crucial processes (the regulation of the response to a cytokine stimulus, regulation of the inflammatory response, positive regulation of cytokine production, cellular response to external stimulus, etc.) and fungal pathways (Th17 cell differentiation, the Toll-like receptor signaling pathway, the C-type lectin receptor signaling pathway and necroptosis). To validate these findings, molecular docking studies were conducted, revealing the binding affinities of the phytochemicals towards selected Candida protein targets of humans (ALB-rutin (-9.7 kJ/mol), STAT1-rutin (-9.2 kJ/mol), STAT3-isoquercetin (-8.7 kJ/mol), IL2-β-carotene (-8.5 kJ/mol), CASP1-β-carotene (-8.2 kJ/mol), TP53-isoquercetin (-8.8 kJ/mol), PPARG-luteolin (-8.3 kJ/mol), TNF-βcarotene (-7.7 kJ/mol), TLR4-rutin (-7.4 kJ/mol) and PTPRC-rutin (-7.0 kJ/mol)). Furthermore, molecular dynamics simulations of rutin-ALB and rutin-STAT1 complex were performed to gain insights into the stability and dynamics of the identified ligand-target complexes over time. Overall, the results not only contribute to the understanding of the molecular interactions underlying the anti-fungal potential of specific phytochemicals of Ajwa dates in humans but also provide a rational basis for the development of novel therapeutic strategies against candidiasis in humans. This study underscores the significance of network pharmacology, molecular docking and dynamics simulations in accelerating the discovery of natural products as effective anti-fungal agents. However, further experimental validation of the identified compounds is warranted to translate these findings into practical therapeutic applications.

Microbial adhesion and biofilm formation by Candida albicans on 3D-printed denture base resins

This study evaluated surface properties and adhesion/biofilm formation by Candida albicans on 3D printed denture base resins used in 3D printing. Disc-shaped specimens (15 mm x 3 mm) of two 3D-printed resins (NextDent Denture 3D+, NE, n = 64; and Cosmos Denture, CO, n = 64) and a heat-polymerized resin (Lucitone 550, LU, control, n = 64) were analyzed for surface roughness (Ra μm) and surface free energy (erg cm-2). Microbiologic assays (90-min adhesion and 48-h biofilm formation by C. albicans) were performed five times in triplicate, with the evaluation of the specimens' surface for: (i) colony forming units count (CFU/mL), (ii) cellular metabolism (XTT assay), and (iii) fluorescence and thickness of biofilm layers (confocal laser scanning microscopy). Data were analyzed using parametric and nonparametric tests (α = 0.05). LU presented higher surface roughness Ra (0.329±0.076 μm) than NE (0.295±0.056 μm) (p = 0.024), but both were similar to CO (0.315±0.058 μm) (p = 1.000 and p = 0.129, respectively). LU showed lower surface free energy (47.47±2.01 erg cm-2) than CO (49.61±1.88 erg cm-2) and NE (49.23±2.16 erg cm-2) (p<0.001 for both). The CO and NE resins showed greater cellular metabolism (p<0.001) and CO only, showed greater colonization (p = 0.015) by C. albicans than LU in the 90-min and 48-hour periods. It can be concluded that both 3D-printed denture base resins are more prone to colonization by C. albicans, and that their surface free energy may be more likely associated with that colonization than their surface roughness.

The research progress in the interaction between Candida albicans and cancers

Candida albicans is an opportunistic pathogenic fungus, which tends to infect the host with defective immune function including cancer patients. A growing number of studies have shown that C. albicans infection increases the host susceptibility to cancer such as oral, gastric, and colorectal cancer. Cancer and anti-cancer treatment may also affect the colonization of C. albicans. C. albicans may promote the development of cancer by damaging mucosal epithelium, inducing the production of carcinogens, triggering chronic inflammation including Th17 cell-mediated immune response. In this article, we aim to elaborate the interaction between C. albicans and cancers development and summarize the potential molecular mechanisms, so as to provide theoretical basis for prevention, diagnosis and treatment of cancers.

Biofilm formation of Candida isolates from xerostomic post-radiotherapy head and neck cancer patients

Oral candidiasis is a common problem in post-radiation head and neck cancer (HNC) patients. While biofilm formation is a crucial virulence factor for Candida colonization, existing information on biofilm formation capability of Candida in cancer patients is scarce.

OBJECTIVE

To evaluate biofilm formation capability of Candida spp. colonized in xerostomic post-radiotherapy HNC patients.

DESIGN

Candida albicans and non-albicans Candida species were previously isolated from xerostomic post-radiation cancer patients and healthy individuals. Biofilm mass and biofilm metabolic activity were investigated by crystal violet and MTT assays, respectively. Their relationship with clinical parameters was analyzed using Mann-Whitney U and Chi-square tests.

RESULTS

A total of 109 and 45 Candida isolates from 64 cancer patients and 34 controls, respectively, were evaluated. Both biofilm mass and metabolic activity of Candida isolates from cancer patients were higher than those from controls. The between-group differences were statistically significant in C. albicans (p < 0.001) for biofilm mass, and in C. tropicalis (p = 0.01) for biofilm metabolic activity. Overall, C. tropicalis was the best biofilm producers in both groups. Additionally, we found that higher biofilm formation among C. albicans was associated with low saliva buffering capacity.

CONCLUSIONS

C. albicans and C. tropicalis isolated from xerostomic post-radiation cancer patients had higher biofilm formation capability than those from healthy individuals. Our findings suggest that, in addition to compromised host factors, higher biofilm formation capability may also contribute to the pathogenesis of oral candidiasis in HNC patients. This novel information potentially adds to proper management for these patients.

Oral Cavity and Candida albicans: Colonisation to the Development of Infection

Candida colonisation of the oral cavity increases in immunocompromised individuals which leads to the development of oral candidiasis. In addition, host factors such as xerostomia, smoking, oral prostheses, dental caries, diabetes and cancer treatment accelerate the disease process. Candida albicans is the primary causative agent of this infection, owing to its ability to form biofilm and hyphae and to produce hydrolytic enzymes and candialysin. Although mucosal immunity is activated, from the time hyphae-associated toxin is formed by the colonising C. albicans cells, an increased number and virulence of this pathogenic organism collectively leads to infection. Prevention of the development of infection can be achieved by addressing the host physiological factors and habits. For maintenance of oral health, conventional oral hygiene products containing antimicrobial compounds, essential oils and phytochemicals can be considered, these products can maintain the low number of Candida in the oral cavity and reduce their virulence. Vulnerable patients should be educated in order to increase compliance.

Effects of benzydamine and mouthwashes containing benzydamine on Candida albicans adhesion, biofilm formation, regrowth, and persistence

Objectives

To assess the effects of benzydamine and mouthwashes (MoWs) containing benzydamine on different stages of Candida albicans biofilm: adhesion, formation, persistence, and regrowth (if perturbed).

Materials and methods

C. albicans CA1398, carrying the bioluminescence ACT1p-gLUC59 fusion product, was employed. Fungal cells were exposed for 1′, 5′, or 15′ to 4 different benzydamine concentrations (0.075 to 0.6%) to 2 mouthwashes (MoWs) containing benzydamine and to a placebo MoW (without benzydamine). Treated cells were tested for adhesion (90 min) and biofilm formation (24-h assay). Next, 24- and 48-h-old biofilms were exposed to benzydamine and MoWs to assess regrowth and persistence, respectively. The effects of benzydamine, MoWs containing benzydamine, and placebo on different biofilm stages were quantified by bioluminescence assay and by the production of quorum sensing (QS) molecules.

Results

Benzydamine and MoWs containing benzydamine impaired C. albicans ability to adhere and form biofilm, counteracted C. albicans persistence and regrowth, and impaired a 48-h-old biofilm. Some of these effects paralleled with alterations in QS molecule secretion.

Conclusions

Our results show for the first time that benzydamine and MoWs containing benzydamine impair C. albicans capacity to form biofilm and counteract biofilm persistence and regrowth.

Clinical relevance

Benzydamine and MoWs containing benzydamine capacity to affect C. albicans biofilm provides an interesting tool to prevent and treat oral candidiasis. Likely, restraining C. albicans colonization through daily oral hygiene may counteract colonization and persistence by other critical oral pathogens, such as Streptococcus mutans, whose increased virulence has been linked to the presence of C. albicans biofilm.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-021-04330-8.

Nystatin effect on chlorhexidine efficacy against Streptococcus mutans as planktonic cells and mixed biofilm with Candida albicans

Objective

The aim of this study was to evaluate the effect of nystatin on the efficacy of chlorhexidine against Streptococcus mutans in planktonic cells and mixed biofilm with Candida albicans.

Material and methods

S. mutans ATCC 25,175 in suspension and also combined with C. albicans ATCC 18,804 in biofilm were cultured. Minimum inhibitory concentration (MIC), crystal violet colorimetric assay, and colony-forming unit counting (CFUs/mL) were performed.

Results

An increased MIC of chlorhexidine against S. mutans was observed when the drugs were administered mixed in a single formulation and with time intervals in between, except for the 30-min interval. The biofilm optical density (OD) in treatments using chlorhexidine and nystatin combined did not significantly differ from chlorhexidine alone. Either in biofilm colorimetric assay or determination of CFUs, the combined treatments with nystatin administered before chlorhexidine had less effect on chlorhexidine efficacy.

Conclusions

Nystatin interferes with the action of chlorhexidine against S. mutans. The antimicrobial effectiveness of the combined drugs depends on their concentration, time interval used, and the planktonic or biofilm behavior of the microorganisms.

Clinical relevance

In view of the great number of patients that can receive a prescription of chlorhexidine and nystatin concomitantly, this study contributes to the knowledge about the effect of the combined drugs. Given the high prevalence of prescriptions of chlorhexidine and nystatin in dentistry, dental professionals should be aware of their possible antagonistic effect.

It Takes Two to Tango: How a Dysregulation of the Innate Immunity, Coupled With Candida Virulence, Triggers VVC Onset

Vulvovaginal candidiasis (VVC) is a symptomatic inflammation of the vagina mainly caused by C. albicans. Other species, such as C. parapsilosis, C. glabrata, C. tropicalis, and C. krusei, are mainly associated to the recurrent form of the disease (RVVC), although with a lower frequency. In its yeast form, C. albicans is tolerated by the vaginal epithelium, but switching to the invasive hyphal form, co-regulated with the expression of genes encoding virulence factors such as secreted aspartyl proteases (Sap) and candidalysin, allows for tissue damage. Vaginal epithelial cells play an important role by impairing C. albicans tissue invasion through several mechanisms such as epithelial shedding, secretion of mucin and strong interepithelial cell connections. However, morphotype switching coupled to increasing of the fungal burden can overcome the tolerance threshold and trigger an intense inflammatory response. Pathological inflammation is believed to be facilitated by an altered vaginal microbiome, i.e., Lactobacillus dysbiosis. Notwithstanding the damage caused by the fungus itself, the host response to the fungus plays an important role in the onset of VVC, exacerbating fungal-mediated damage. This response can be triggered by host PRR-fungal PAMP interaction and other more complex mechanisms (i.e., Sap-mediated NLRP3 activation and candidalysin), ultimately leading to strong neutrophil recruitment. However, recruited neutrophils appear to be ineffective at reducing fungal burden and invasion; therefore, they seem to contribute more to the symptoms associated with vaginitis than to protection against the disease. Recently, two aspects of the vulvovaginal environment have been found to associate with VVC and induce neutrophil anergy in vitro: perinuclear anti-neutrophil cytoplasmic antibodies (pANCA) and heparan sulfate. Interestingly, CAGTA antibodies have also been found with higher frequency in VVC as compared to asymptomatic colonized women. This review highlights and discusses recent advances on understanding the VVC pathogenesis mechanisms as well as the role of host defenses during the disease.

Oral Candidiasis in Hematological Malignancy Patients: Identification and Antifungal Susceptibility Patterns of Isolates

Background: Oropharyngeal candidiasis is a fungal infection in the mouth caused by Candida species. Oropharyngeal candidiasis is a major problem among hematologic malignancy patients. Objectives: The present study was designed to identify and evaluate antifungal susceptibility patterns of Candida spp. isolated from hematological malignancy patients with oral candidiasis. Methods: Samples were collected from the oral cavity of 138 patients and confirmed for oropharyngeal candidiasis by microscopic examination and fungal culture. Isolated Candida strains were identified by ITS-PCR. Hyphal wall protein 1 (HWP1) was amplified to differentiate the Candida albicans complex. In vitro antifungal susceptibility tests against fluconazole, amphotericin B, and caspofungin were performed according to CLSI M27-A3/S4. Results: The study enrolled 120 patients, including 74 (61.66%) females and 46 (38.33%) males. The mean age of affliction by fungal infections was 42 ± 8 years. Patients with acute myeloid leukemia (44%) comprised the majority of cases. The most commonly isolated species among patients were C. albicans (n = 110; 91.6%), C. glabrata (n = 8; 6.6%), and C. africana (n = 2; 2.8%). The overall resistance of C. albicans was 2.7% to fluconazole, and 1.8% to amphotericin B. Candida glabrata showed 12.5% resistance to amphotericin B. All Candida spp. isolates from patients were susceptible to caspofungin. Conclusions: Local information about the increasing resistance to fluconazole in both C. albicans and non albicans Candida species and their antifungal susceptibility is useful for deciding on antifungal prophylaxis and selecting the empirical therapy of cancer patients.

Prevalence and susceptibility profile of Candida spp. isolated from patients in cancer therapy

OBJECTIVE

This study determined the prevalence of Candida spp. in the saliva of cancer patients. Furthermore, we assessed the antimicrobial activity of mouthwashes against the isolated strains and its susceptibility to amphotericin B and fluconazole.

METHODS

Thirty-four cancer patients undergoing radiotherapy, chemotherapy alone or combined treatment were investigated for oral Candida spp. colonization and compared in regard to mucositis presence. The maximum inhibitory dilution was used to assess the antimicrobial activity of Periogard®, Cepacol® Cool Ice and 0.12 % Chlorhexidine Digluconate mouthwashes against the isolates. In parallel, susceptibility to amphotericin B and fluconazole was determined by agar-based E-test. Data did not adhere to normal distribution as inferred by the Shapiro-Wilk test and statistical analysis was conducted by non-parametric McNemar test (α0.05).

RESULTS

Twenty-seven participants (79.4 %) were male, 19 (55.9 %) had mucositis and 9 (26.5 %) were colonized by Candida spp. 12 different strains of Candida spp. were isolated, being Candida albicans the most prevalent strain. Risk of Candida spp. colonization was increased by almost twofold among the participants with mucositis (odds ratio: 1.84; 95 % confidence interval: 0.37-9.07). Mouthwash Cepacol® Cool Ice presented better antimicrobial activity against Candida spp. while 0.12 % Chlorhexidine exhibited the worst activity. All strains were sensitive to amphotericin B, and 2 non-albicans strains were dose-dependent sensitive to fluconazole.

CONCLUSION

Considering the increased risk of colonization byCandida spp. in patients with mucositis, and the emergence of antifungal drug resistance, the antiseptics use could benefit the maintenance of cancer patient's oral health.

Change of saliva composition with radiotherapy

OBJECTIVE

The aim of this study was to analyze the physiological and microbiological changes of saliva from patients with head and neck cancer during and after intensity-modulated radiotherapy (IMRT).

DESIGN

In this prospective clinical trial saliva samples and oral candida swabs were collected from patients receiving IMRT due to head and neck cancer (examination group). The first measurement was scheduled before radiotherapy, the other measurements during and after radiotherapy up to a one year follow-up. Additionally samples from healthy controls were collected over six weeks. Salivary flow rate and pH were measured. Microbiological analysis of cariogenic and periodontopathogenic taxa was performed by fluorescence in situ hybridization and oral Candida spp occurrence was evaluated by swab tests.

RESULTS

11 patients and 19 controls were included. The salivary flow rate and the unstimulated pH of the examination group were significantly reduced during radiotherapy compared with the measurement before radiotherapy and to the control group. Total bacteria, streptococci and lactobacilli numbers slightly increased after radiotherapy, resuming baseline levels after one year. Mutans streptococci, Porphyromonas gingivalis and Treponema denticola were barely detectable, whereas Tannerella forsythia slightly increased following radiotherapy. No differences in Candida levels were observed in the study.

CONCLUSIONS

Salivary changes in quantitative, qualitative and microbial composition occur during and after radiotherapy, with resumption of the measurements towards baseline levels after one year. While low levels of cariogenic and periodontopathogenic species were detected, the lower pH and salivary flow combined with increased numbers of aciduric and acidogenic lactobacilli corroborates a higher risk for caries, necessitating prevention.

Bacterial endotoxins and microorganisms in the oral cavities of patients on cancer therapy

OBJECTIVES

This study investigated the presence of Streptococci, Staphylococci, aerobic gram negative bacteria (AGNB), Candida and bacterial endotoxins in the oral cavities of patients receiving chemo- and/or radiotherapy for cancer.

METHODS

Samples of oral cavity rinse were collected from 100 patients on cancer treatment and 70 healthy individuals. Demographic and clinical data were recorded. Samples were cultured onto various agar plates for qualitative and quantitative analysis and tested for the presence of endotoxin. Results were analysed using the Mann-Whitney and chi-square tests.

RESULTS

In cancer patients, S. aureus counts were high and 66.7% of patients on chemo- and radiotherapy carried these bacteria (p=<0.05). The Candida carrier rate was significantly (p < 0.01) high in cancer patients (54%). No significant difference was found in the carrier rate of Streptococci and AGNB between the healthy and cancer group as well as between the cancer patients with chemo and radio- and chemotherapy alone. No significant difference was found in the level of endotoxin between the cancer patients and healthy individuals, and cancer patients with and without AGNB.

CONCLUSIONS

No differences in the prevalence of bacteria and bacterial endotoxins were found between the cancer patients and healthy individuals. Oral cavity endotoxins did not correlate with the carriage of AGNB. However, due to the high prevalence in cancer patients, the role of Candida species and S. aureus in the pathology may not be excluded.

Chemotherapy-induced oral mucositis and associated infections in a novel organotypic model

Oral mucositis is a common side effect of cancer chemotherapy, with significant adverse impact on the delivery of anti-neoplastic treatment. There is a lack of consensus regarding the role of oral commensal microorganisms in the initiation or progression of mucositis because relevant experimental models are non-existent. The goal of this study was to develop an in vitro mucosal injury model that mimics chemotherapy-induced mucositis, where the effect of oral commensals can be studied. A novel organotypic model of chemotherapy-induced mucositis was developed based on a human oral epithelial cell line and a fibroblast-embedded collagen matrix. Treatment of organotypic constructs with 5-fluorouracil (5-FU) reproduced major histopathologic characteristics of oral mucositis, such as DNA synthesis inhibition, apoptosis and cytoplasmic vacuolation, without compromising the three-dimensional structure of the multilayer organotypic mucosa. Although structural integrity of the model was preserved, 5-FU treatment resulted in a widening of epithelial intercellular spaces, characterized by E-cadherin dissolution from adherens junctions. In a neutrophil transmigration assay we discovered that this treatment facilitated transport of neutrophils through epithelial layers. Moreover, 5-FU treatment stimulated key proinflammatory cytokines that are associated with the pathogenesis of oral mucositis. 5-FU treatment of mucosal constructs did not significantly affect fungal or bacterial biofilm growth under the conditions tested in this study; however, it exacerbated the inflammatory response to certain bacterial and fungal commensals. These findings suggest that commensals may play a role in the pathogenesis of oral mucositis by amplifying the proinflammatory signals to mucosa that is injured by cytotoxic chemotherapy.

γ-irradiation from radiotherapy improves the virulence potential of Candida tropicalis

AIM

To evaluate if radiation used in radiotherapy can cause changes in the virulence potential of Candida tropicalis ATCC 750.

MATERIALS & METHODS

C. tropicalis was exposed in vitro to identical dose and scheme of irradiation would be used in patients with head and neck cancer. Some virulence parameters were analyzed before and after irradiation.

RESULTS

Colony morphologies were irreversibly affected by irradiation. Increase in growth rate, filamentation, adhesion on cell lines and phagocytosis process were also observed. Overall the irradiated C. tropicalis cells became more efficient at causing systemic infection in mice.

CONCLUSION

γ-radiation induced important changes in C. tropicalis increasing its virulence profile, which could directly affect the relationship between yeasts and hosts.