Oral infections caused by yeasts in patients with head and neck cancer undergoing radiotherapy. Identification of the yeasts and evaluation of their antifungal susceptibility

Microbiome in radiotherapy: an emerging approach to enhance treatment efficacy and reduce tissue injury

Radiotherapy is a widely used cancer treatment that utilizes powerful radiation to destroy cancer cells and shrink tumors. While radiation can be beneficial, it can also harm the healthy tissues surrounding the tumor. Recent research indicates that the microbiota, the collection of microorganisms in our body, may play a role in influencing the effectiveness and side effects of radiation therapy. Studies have shown that specific species of bacteria living in the stomach can influence the immune system's response to radiation, potentially increasing the effectiveness of treatment. Additionally, the microbiota may contribute to adverse effects like radiation-induced diarrhea. A potential strategy to enhance radiotherapy outcomes and capitalize on the microbiome involves using probiotics. Probiotics are living microorganisms that offer health benefits when consumed in sufficient quantities. Several studies have indicated that probiotics have the potential to alter the composition of the gut microbiota, resulting in an enhanced immune response to radiation therapy and consequently improving the efficacy of the treatment. It is important to note that radiation can disrupt the natural balance of gut bacteria, resulting in increased intestinal permeability and inflammatory conditions. These disruptions can lead to adverse effects such as diarrhea and damage to the intestinal lining. The emerging field of radiotherapy microbiome research offers a promising avenue for optimizing cancer treatment outcomes. This paper aims to provide an overview of the human microbiome and its role in augmenting radiation effectiveness while minimizing damage.

Symptom Patterning Across the Cancer Care Trajectory for Patients Receiving Chemoradiation for Head and Neck Cancer: A Retrospective Longitudinal Study Using Latent Transition Analysis

BACKGROUND

Patients with head and neck cancer (HNC) experience a multitude of symptoms because of the tumor and its treatment.

OBJECTIVE

To identify the symptom patterns present in cancer treatment and survivorship periods for patients with HNC using latent class analysis.

METHODS

A retrospective longitudinal chart review was conducted to examine symptoms reported by patients who received concurrent chemoradiation for HNC in a regional Northeastern United States cancer institute. Latent class analysis was performed to identify the latent classes present across multiple timepoints during treatment and survivorship for the most commonly reported symptoms.

RESULTS

In 275 patients with HNC, the latent transition analysis revealed 3 latent classes for both treatment and survivorship periods: (1) mild, (2) moderate, and (3) severe symptoms. Patients were more likely to report a greater number of symptoms in a more severe latent class. During treatment, moderate and severe classes had representation of all most common symptoms: pain, mucositis, taste alterations, xerostomia, dysphagia, and fatigue. Different symptom patterns emerged for survivorship, with prominence of taste alterations and xerostomia across all classes, and all symptoms present in the severe class. The probability of symptom expression varied more in the survivorship period compared with the treatment period.

CONCLUSIONS

Patients reported numerous symptoms during active treatment persisting into survivorship. Patients tended to transition to more severe symptomatology as treatment progressed and to more moderate symptomatology as survivorship evolved.

IMPLICATIONS FOR PRACTICE

Examining the trend of persistent moderate symptomatology into survivorship is useful to optimize symptom management.

Rare Yeasts in Latin America: Uncommon Yet Meaningful

Systemic infections caused by rare yeasts are increasing given the rise in immunocompromised or seriously ill patients. Even though globally, the clinical significance of these emerging opportunistic yeasts is increasingly being recognized, less is known about the epidemiology of rare yeasts in Latin America. This review collects, analyzes, and contributes demographic and clinical data from 495 cases of infection caused by rare yeasts in the region. Among all cases, 32 species of rare yeasts, distributed in 12 genera, have been reported in 8 Latin American countries, with Trichosporon asahii (49.5%), Rhodotorula mucilaginosa (11.1%), and Saccharomyces cerevisiae (7.8%) the most common species found. Patients were mostly male (58.3%), from neonates to 84 years of age. Statistically, surgery and antibiotic use were associated with higher rates of Trichosporon infections, while central venous catheter, leukemia, and cancer were associated with higher rates of Rhodotorula infections. From all cases, fungemia was the predominant diagnosis (50.3%). Patients were mostly treated with amphotericin B (58.7%). Crude mortality was 40.8%, with a higher risk of death from fungemia and T. asahii infections. Culture was the main diagnostic methodology. Antifungal resistance to one or more drugs was reported in various species of rare yeasts.

The microbiota and radiotherapy for head and neck cancer: What should clinical oncologists know?

Radiotherapy is a linchpin in head and neck squamous cell carcinoma (HN-SCC) treatment. Modulating tumour and/or normal tissue biology offers opportunities to further develop HN-SCC radiotherapy. The microbiota, which can exhibit homeostatic properties and be a modulator of immunity, has recently received considerable interest from the Oncology community. Microbiota research in head and neck oncology has also flourished. However, available data are difficult to interpret for clinical and radiation oncologists. In this review, we focus on how microbiota research can contribute to the improvement of radiotherapy for HN-SCC, focusing on how current and future research can be translated back to the clinic. We include in-depth discussions about the microbiota, its multiple habitats and relevance to human physiology, mechanistic interactions with HN-SCC, available evidence on microbiota and HNC oncogenesis, efficacy and toxicity of treatment. We discuss clinically-relevant areas such as the role of the microbiota as a predictive and prognostic biomarker, as well as the potential of leveraging the microbiota and its interactions with immunity to improve treatment results. Importantly, we draw parallels with other cancers where research is more mature. We map out future directions of research and explain clinical implications in detail.

An Integrative Review of the Role of the Oral and Gut Microbiome in Oral Health Symptomatology During Cancer Therapy

PROBLEM IDENTIFICATION

Both chemotherapy and radiation therapy cause considerable symptom burden on patients' oral health, influencing nutritional status and quality of life. The role of the oral and gut microbiome in oral health alterations during cancer therapy is an emerging area of science in symptom management.

LITERATURE SEARCH

PubMed®, CINAHL®, and Scopus® were searched for articles published from January 2000 through July 2020.

DATA EVALUATION

Articles published in English that were focused on chemotherapy and/or radiation therapy were included in the review.

SYNTHESIS

Of the 22 identified studies, 12 described oral health symptoms during chemotherapy and radiation therapy for head and neck cancer. Ten studies assessed symptoms during treatment for a variety of solid tumors and blood cancers, with four of these describing microbial interventions for the management of oral mucositis. Interventions varied, but the results supported the benefits of probiotics and synbiotics in reducing mucositis severity. Overall, less diverse oral and gut microbiome environments were associated with increased severity of oral health symptomatology.

IMPLICATIONS FOR PRACTICE

Additional research is needed to determine how the oral and gut microbiome and microbial interventions may be used to improve oral health management during cancer treatment.

[Optimization of variables in photodynamic antifungal assays against Candida species]

Oral infections due to yeasts of the genus Candida are very common in patients with predisposing factors, such as physiological conditions or certain underlying diseases. Moreover, oral candidiasis can also evolve into disseminated forms. In this work, strains of the genus Candida were studied to establish the optimal radiation conditions for photosensitizing compounds, in a photodynamic antifungal therapy protocol. A total of 39 isolates were evaluated. The strains were exposed to twelve dyestuffs, eight radiation sources and three different exposure times. Orthotoluidine blue exhibited good photodynamic activity, in combination with exposure to a 20W reflector lamp LED (light-emitting diode) light for 60minutes. When considering the difficulties of using conventional antifungal drugs, the emergence of resistant strains, recurrences, and adverse reactions of certain commonly used drugs, the photodynamic antifungal therapy is a promising strategy for the treatment of localized infections.

Candida prevalence in saliva before and after oral cancer treatment

BACKGROUND

Previous studies have shown an increased prevalence of candidiasis in patients receiving radiotherapy for head and neck cancer. However, little is known of the effect the different cancer treatment modalities have on the oral Candida status.

OBJECTIVE AND HYPOTHESIS

The objective of this study was to investigate the change in salivary Candida status of oral squamous cell carcinoma (OSCC) patients undergoing cancer treatment. The hypothesis was that cancer treatments change the oral microbial environment favouring an increase in the prevalence of more pathogenic non-albicans Candida (NAC).

METHODS

We collected paraffin-stimulated saliva from 44 OSCC patients before surgery and after a minimum of 19 months of follow-up. Chromagar, Bichro-Dupli-test and API ID 32 C were used for identification of different Candida species and results were analysed statistically.

RESULTS

At both timepoints, 75% of samples were Candida positive with C. albicans being the most common yeast. NAC strains were present in 16% of the pre-operative samples and 14% of the follow-up samples. The NAC species found were C. dubliniensis, C. krusei, C. guilliermondii (preoperatively only) and C. glabrata (at follow-up only). In 73% of the cases, the salivary Candida status remained unchanged. There was an 18% increase in the prevalence of candidiasis. However, the different treatment modalities did not statistically significantly affect the Candida status of the patients.

CONCLUSION

The intraindividual prevalence of salivary Candida among OSCC patients seems to be stable and different treatment modalities have little to no effect on the salivary Candida status.

Development and machine-learning optimization of mucoadhesive nanostructured lipid carriers loaded with fluconazole for treatment of oral candidiasis

The aim of this work was to prepare and optimize mucoadhesive nanostructured lipid carrier (NLC) impregnated with fluconazole for better management of oral candidiasis. The NLCs were fabricated using an emulsification/sonication technique. The nanoparticles consisted of stearic acid, oleic acid, Pluronic F127, and lecithin. Box-Behnken design, artificial neural networking, and variable weight desirability were employed to optimize the joint effect of drug concentration in the drug/lipid mixture, solid lipid concentration in the solid/liquid lipid mixture, and surfactant concentration in the total mixture on size and entrapment. The optimized NLCs were coated with chitosan. The nanoparticles were characterized by surface charge, spectroscopic, thermal, morphological, mucoadhesion, release, histopathological, and antifungal properties. The nanoparticles are characterized by a particle size of 335 ± 13.5 nm, entrapment efficiency of 73.1 ± 4.9%, sustained release, minor histopathological effects on rabbit oral mucosa, and higher fungal inhibition efficiency for an extended period of time compared with fluconazole solution. Coating the nanoparticles with chitosan increased its adhesion to rabbit oral buccal mucosa and improved its anti-candidiasis activity. It is concluded that mucoadhesive lipid-based nanoparticles amplify the effect of fluconazole on Candida albicans in vitro. This finding warrants pre-clinical and clinical studies in oral candidiasis disease models to corroborate in vitro findings.

Effect of probiotic bacteria on oral Candida in head- and neck-radiotherapy patients: A randomized clinical trial

Objective

The aim of the study is to assess the effect of probiotic bacteria on oral Candida counts in cancer patients who are undergoing head- and neck-radiotherapy in a tertiary care center.

Study Design

The study was a randomized clinical trial including 90 patients who just completed head- and neck-radiotherapy.

Materials and Methods

Participants were randomly allocated into three equal sized groups, i.e., probiotics group, candid group, and combination groups. Oral rinse samples of the patients were collected before and after the intervention for the identification of Candida. The samples were incubated on Sabouraud's Dextrose Agar with Chloramphenicol at 37°C for 48 h, to assess the counts of colony-forming units/milliliter (CFU/ml) of Candida in saliva, and further on chrome agar plates to identify the Candida spp. Data were analyzed using mixed ANOVA to compare mean CFU/ml of Candida among three groups before and after the intervention.

Results

A total of 86 patients were included in the final analysis and there was a statistically significant reduction in mean Candida spp. Counts (CFU/ml) after intervention in all the three groups (P = 0.000) and significant reductions identified in both probiotic and combination therapy groups. Apart from reduction in Candida albicans, significant decrease in Candida glabrata and Candida tropicalis was observed after probiotics usage compared to other groups.

Conclusions

The present study suggests that probiotic bacteria were effective in reducing oral Candida spp which can be recommended alone or in combination with traditional antifungal agents for effective reduction in oral Candida in head- and neck-radiotherapy patients.

Antifungal photosensitive activity of Porophyllum obscurum (Spreng.) DC.: Correlation of the chemical composition of the hexane extract with the bioactivity

We report Porophyllum obscurum as a source of new photosensitizers with potential use in Photodynamic Therapy as an alternative for oropharyngeal candidiasis treatment. The antifungal photosensitive activity of different extracts from P. obscurum was evaluated by using microdilution and bioautographic assays. The Minimum Fungicidal Concentration for hexanic extract under UV-A irradiation was 0.98μg/mL, but it was inactive in experiments without irradiation. The bioassay-guided fractionation of this extract led to the isolation of four thiophenes responsible for the photosensitive activity: 2,2':5'2″terthiophene, 5-(3-buten-1-ynyl)-2,2'-bithiophene, 5-(4-acetoxy-1-butenyl)-2,2'- bithiophene and 5-(4-hydroxy-1-butenyl)-2,2'- bithiophene, with Minimum Fungicidal Concentrations ranging 0.24-7.81μg/mL under UV-A irradiation. The activity of the hexanic extract was evaluated against 25 clinical strains of Candida spp. isolates as etiological agents of oropharyngeal candidiasis. No differences in susceptibility were observed in strains resistant and susceptible to conventional antifungal drugs. Qualitative and quantitative chemical analyses of seven samples of P. obscurum collected in four different phenological stages were carried out showing that full flowering stage possesses the highest thiophenes content. These data also allowed us to establish a correlation between the thiophene composition of the different extracts and their antifungal photosensitive activity, according to a second order polynomial model with the equation: y=11.2603-0.6831*x+0.0108*x². The thiophenes isolated were the responsible of antifungal photosensitive activity and can be used for the future standardization of the extract. Results showed that P. obscurum hexanic extract could be potentially developed as an Herbal Medicinal Product to be applied as a photosensitizer in Photodynamic Therapy.

Development, characterization, and in vivo assessment of mucoadhesive nanoparticles containing fluconazole for the local treatment of oral candidiasis

This study aimed to develop a suitable buccal mucoadhesive nanoparticle (NP) formulation containing fluconazole for the local treatment of oral candidiasis. The suitability of the prepared formulations was assessed by means of particle size (PS), polydispersity index, and zeta potential measurements, morphology analysis, mucoadhesion studies, drug entrapment efficiency (EE), in vitro drug release, and stability studies. Based on the optimum NP formulation, ex vivo drug diffusion and in vitro cytotoxicity studies were performed. Besides, evaluation of the antifungal effect of the optimum formulation was evaluated using agar diffusion method, fungicidal activity-related in vitro release study, and time-dependent fungicidal activity. The effect of the optimum NP formulation on the healing of oral candidiasis was investigated in an animal model, which was employed for the first time in this study. The zeta potential, mucoadhesion, and in vitro drug release studies of various NP formulations revealed that chitosan-coated NP formulation containing EUDRAGIT(®) RS 2.5% had superior properties than other formulations. Concerning the stability study of the selected formulation, the formulation was found to be stable for 6 months. During the ex vivo drug diffusion study, no drug was found in receptor phase, and this is an indication of local effect. The in vitro antifungal activity studies showed the in vitro efficacy of the NP against Candida albicans for an extended period. Also, the formulation had no cytotoxic effect at the tested concentration. For the in vivo experiments, infected rabbits were successfully treated with local administration of the optimum NP formulation once a day. This study has shown that the mucoadhesive NP formulation containing fluconazole is a promising candidate with once-a-day application for the local treatment of oral candidiasis.

Warfarin treatment and antifungal agent caspofungin for severe fungal infection in a patient previously treated with radiotherapy for oropharyngeal cancer

Drug–Drug interactions is important when caring for warfarin‐treated patients. We examined the impact on INR with coadministration of warfarin and caspofungin and showed no affect on the INR. Coadministrations of fluconazole lead to a marked increase in INR. We concluded that administration of caspofungin and warfarin was safe.

Antifungal activity against Candida albicans of starch Pickering emulsion with thymol or amphotericin B in suspension and calcium alginate films

Conventional antifungal treatments against Candida albicans in the oral cavity often result in increased cytotoxicity. The goal of this study was to determine the potential of starch Pickering emulsion as a delivery vehicle for an antifungal natural phenolic compound such as thymol in simulated saliva fluid (SSF) compared to amphotericin B. An oil-in-water (o/w) emulsion was stabilized using starch particles. Physical stability of the emulsion and disruption induced by α-amylase activity in SSF was evaluated. Encapsulated thymol in o/w emulsion was compared to encapsulated amphotericin B for antifungal activity against C. albicans in suspension using emulsions or zone inhibition assay on agar plates using emulsions dispersed in alginate films. Results showed that the emulsions were stable for at least three weeks. Digestion of the emulsion by α-amylase led to coalescence of emulsion droplets. The antifungal activity of thymol and amphotericin B in emulsion formulation was enhanced upon incubation with α-amylase. Results from the zone inhibition assay demonstrated efficacy of the emulsions dispersed in alginate films. Interestingly, addition of α-amylase to the alginate films resulted in a decreased inhibitory effect. Overall, this study showed that starch Pickering emulsions have a potential to deliver hydrophobic antifungal compounds to treat oral candidiasis.

Exploring the variation of oral microbiota in supragingival plaque during and after head-and-neck radiotherapy using pyrosequencing

OBJECTIVE

The aim of this article was to study the variation in oral microflora of the subgingival plaque during and after radiotherapy.

DESIGN

During and after radiotherapy, microbial samples were collected at seven time points (early stage, medium stage, and later stage of radiotherapy, and 1 month, 3 months, 6 months, and 1 year after radiotherapy) in three subjects for a total of 21 samples. Polymerase chain reaction (PCR) amplification was carried out on the 16S rDNA hypervariable V1-V3 region, and then the PCR products were determined by high-throughput pyrosequencing.

RESULTS

The rarefaction curve indicating the richness of the microflora demonstrated that the number of operational taxonomic units (OTUs) was in decline from the early stage of radiotherapy to the time point 1 month after radiotherapy and then trended upward. The Shannon diversity index declined during radiotherapy (ranging from 4.59 to 3.73), and generally rose after radiotherapy, with the lowest value of 3.5 (1 month after radiotherapy) and highest value of 4.75 (6 months after radiotherapy). A total of 120 genera were found; five genera (Actinomyces, Veillonella, Prevotella, Streptococcus, Campylobacter) were found in all subjects across all time points.

CONCLUSION

The richness and diversity of oral ecology decreased with increased radiation dose, and it was gradually restored with time.

Photodynamic inactivation of oropharyngeal Candida strains

Oropharyngeal candidiasis (OPC) is an infection frequent in immunocompromised patients. Photodynamic therapy is an alternative to conventional treatments, based on the utilization of compounds that inhibit or kill microorganisms only under the effect of light, process known as Photodynamic Inactivation (PDI). In the present study, PDI of Candida spp. by the natural product α-terthienyl (α-T) was investigated following the guidelines of CLSI M27-A3, under UV-A light irradiation. The optimal values of two variables, exposure irradiation time (ET) and distance to the irradiation source (DIS) were established by employing Design Expert Software (DES). For this purpose, a panel of Candida strains isolated from OPC (C. albicans, C. tropicalis, C. parapsilosis and C. krusei) was employed and optimal values were 5 min (ET) and between 6.06 and 6.43 cm (DIS) with a desirability factor of 0.989. α-T plus UV-A light in the optimal conditions caused a complete reduction in viable cells in 5 min which was demonstrated by viable cells reduction assays and confocal microscopy after vital staining (propidium iodide/fluorescein diacetate). The germ tube formation of C. albicans was inhibited by α-T at sub-inhibitory concentrations. Results showed that α-T plus UV-A light could constitute an alternative for OPC treatments at the optimal conditions determined here.

Species distribution and susceptibility profile to fluconazole, voriconazole and MXP-4509 of 551 clinical yeast isolates from a Romanian multi-centre study

This is the first multi-centre study regarding yeast infections in Romania. The aim was to determine the aetiological spectrum and susceptibility pattern to fluconazole, voriconazole and the novel compound MXP-4509. The 551 isolates were identified using routine laboratory methods, matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF MS) and DNA sequence analysis. Susceptibility testing was performed using the European Committee for Antimicrobial Susceptibility Testing (EUCAST) method and breakpoints. The yeasts originated from superficial infections (SUP, 51.5 %), bloodstream infections (BSI, 31.6 %) and deep-seated infections (DEEP, 16.9 %), from patients of all ages. Nine genera and 30 species were identified. The 20 Candida species accounted for 94.6 % of all isolates. C. albicans was the overall leading pathogen (50.5 %). Lodderomyces elongisporus is reported for the first time as a fungaemia cause in Europe. C. glabrata and Saccharomyces cerevisiae, as well as the non-Candida spp. and non-albicans Candida spp. groups, showed decreased fluconazole susceptibility (<75 %). The overall fluconazole resistance was 10.2 %. C. krusei accounted for 27 of the 56 fluconazole-resistant isolates. The overall voriconazole resistance was 2.5 % and was due mainly to C. glabrata and C. tropicalis isolates. Fluconazole resistance rates for the three categories of infection were similar to the overall value; voriconazole resistance rates differed: 4 % for BSI, 3.2 % for DEEP and 1.4 % for SUP. The antifungal activity of MXP-4509 was superior to voriconazole against C. glabrata and many fluconazole-resistant isolates. There was a large percentage of non-albicans Candida isolates. A large part of the high fluconazole resistance was not acquired but intrinsic, resulting from the high percentage of C. krusei.