Exploring the dynamics of mixed-species biofilms involving Candida spp. and bacteria in cystic fibrosis.

Cystic fibrosis (CF) is an inherited disease that results from mutations in the gene responsible for the cystic fibrosis transmembrane conductance regulator (CFTR). The airways become clogged with thick, viscous mucus that traps microbes in respiratory tracts, facilitating colonization, inflammation and infection. CF is recognized as a biofilm-associated disease, it is commonly polymicrobial and can develop in biofilms. This review discusses Candida spp. and both Gram-positive and Gram-negative bacterial biofilms that affect the airways and cause pulmonary infections in the CF context, with a particular focus on mixed-species biofilms. In addition, the review explores the intricate interactions between fungal and bacterial species within these biofilms and elucidates the underlying molecular mechanisms that govern their dynamics. Moreover, the review addresses the multifaceted issue of antimicrobial resistance in the context of CF-associated biofilms. By synthesizing current knowledge and research findings, this review aims to provide insights into the pathogenesis of CF-related infections and identify potential therapeutic approaches to manage and combat these complex biofilm-mediated infections.

Evaluation of mixed biofilm production by Candida spp. and Staphylococcus aureus strains co-isolated from cystic fibrosis patients in northwest Algeria.

Cystic fibrosis patients' lungs are chronically colonized by multiple microbial species capable of forming biofilms. This study aimed to characterize the polymicrobial biofilm formed by Candida spp. and S. aureus, co-isolated from sputum samples of cystic fibrosis patients regarding microbial density, metabolic activity, and structure. 67 samples from 28 patients were collected with a 96% alteration rate. 34% showed alterations by both Candida spp. and Gram-positive bacteria, predominantly Candida spp. and S. aureus in 77% of cases, accounting for 6 associations. Biofilm biomass was quantified using the crystal violet assay, and metabolic activity was assessed using the MTT reduction assay. Scanning electron microscopy analyzed the C. tropicalis/S. aureus24 biofilm architecture. Candida spp. isolates demonstrated the ability to form mixed biofilms with S. aureus. The C. tropicalis/S. aureus24 association exhibited the highest production of biofilm and metabolic activity, along with the C. albicans17/C. rugosa/S. aureus7 in both single and mixed biofilms.

Interactions of Both Pathogenic and Nonpathogenic CUG Clade Candida Species with Macrophages Share a Conserved Transcriptional Landscape.

Candida species are a leading cause of opportunistic, hospital-associated bloodstream infections with high mortality rates, typically in immunocompromised patients. Several species, including Candida albicans, the most prevalent cause of infection, belong to the monophyletic CUG clade of yeasts. Innate immune cells such as macrophages are crucial for controlling infection, and C. albicans responds to phagocytosis by a coordinated induction of pathways involved in catabolism of nonglucose carbon sources, termed alternative carbon metabolism, which together are essential for virulence. However, the interactions of other CUG clade species with macrophages have not been characterized. Here, we analyzed transcriptional responses to macrophage phagocytosis by six Candida species across a range of virulence and clinical importance. We define a core induced response common to pathogenic and nonpathogenic species alike, heavily weighted to alternative carbon metabolism. One prominent pathogen, Candida parapsilosis, showed species-specific expansion of phagocytosis-responsive genes, particularly metabolite transporters. C. albicans and Candida tropicalis, the other prominent pathogens, also had species-specific responses, but these were largely comprised of functionally uncharacterized genes. Transcriptional analysis of macrophages also demonstrated highly correlated proinflammatory transcriptional responses to different Candida species that were largely independent of fungal viability, suggesting that this response is driven by recognition of conserved cell wall components. This study significantly broadens our understanding of host interactions in CUG clade species, demonstrating that although metabolic plasticity is crucial for virulence in Candida, it alone is not sufficient to confer pathogenicity. Instead, we identify sets of mostly uncharacterized genes that may explain the evolution of pathogenicity. IMPORTANCE Candidiasis is a major fungal infection by Candida species, causing life-threatening invasive disease in immunocompromised patients. C. albicans, which is adapted to commensalism of human mucosae, is the most common cause. While several other species cause infection, most are less prevalent or less virulent. As innate immune cells are the primary defense against Candida infection, we compared the transcriptional responses of C. albicans and related species to phagocytosis by macrophages, to understand the basis of variation in pathogenesis. This response, including the metabolic remodeling required for virulence in C. albicans, was strikingly conserved across the virulence spectrum. Macrophage responses to different species were also highly similar. This study indicates that important elements of host-pathogen interactions in C. albicans are not driven by adaptation to the mammalian host and improves our understanding of pathogenicity in opportunistic fungal species that are understudied but collectively impose a significant threat of their own.

Azole-triphenylphosphonium conjugates combat antifungal resistance and alleviate the development of drug-resistance.

Azole antifungals are commonly used to treat fungal infections but have resulted in the occurrence of drug resistance. Therefore, developing azole derivatives (AZDs) that can both combat established drug-resistant fungal strains and evade drug resistance is of great importance. In this study, we synthesized a series of AZDs with a fluconazole (FLC) skeleton conjugated with a mitochondria-targeting triphenylphosphonium cation (TPP+). These AZDs displayed potent activity against both azole-sensitive and azole-resistant Candida strains without eliciting obvious resistance. Moreover, two representative AZDs, 20 and 25, exerted synergistic antifungal activity with Hsp90 inhibitors against C. albicans strains resistant to the combination treatment of FLC and Hsp90 inhibitors. AZD 25, which had minimal cytotoxicity, was effective in preventing C. albicans biofilm formation. Mechanistic investigation revealed that AZD 25 inhibited the biosynthesis of the fungal membrane component ergosterol and interfered with mitochondrial function. Our findings provide an alternative approach to address fungal resistance problems.

Lead optimization generates selenium-containing miconazole CYP51 inhibitors with improved pharmacological profile for the treatment of fungal infections.

A series of selenium-containing miconazole derivatives were identified as potent antifungal drugs in our previous study. Representative compound A03 (MIC = 0.01 µg/mL against C.alb. 5314) proved efficacious in inhibiting the growth of fungal pathogens. However, further study showed lead compound A03 exhibited potential hemolysis, significant cytotoxic effect and unfavorable metabolic stability and was therefore modified to overcome these drawbacks. In this article, the further optimization of selenium-containing miconazole derivatives resulted in the discovery of similarly potent compound B17 (MIC = 0.02 µg/mL against C.alb. 5314), exhibiting a superior pharmacological profile with decreased rate of metabolism, cytotoxic effect and hemolysis. Furthermore, compound B17 showed fungicidal activity against Candida albicans and significant effects on the treatment of resistant Candida albicans infections. Meanwhile, compound B17 not only could reduce the ergosterol biosynthesis pathway by inhibiting CYP51, but also inhibited biofilm formation. More importantly, compound B17 also shows promising in vivo efficacy after intraperitoneal injection and the PK study of compound B17 was evaluated. In addition, molecular docking studies provide a model for the interaction between the compound B17 and the CYP51 protein. Overall, we believe that these selenium-containing miconazole compounds can be further developed for the potential treatment of fungal infections.

Synergistic antifungal effects of curcumin derivatives as fungal biofilm inhibitors with fluconazole.

Lack of novel antifungal agents and severe drug resistance has led to high incidence and associated mortality of invasive fungal infections. To tackle the challenges, novel antifungal agents with anti-resistant potency are highly desirable. Thus, derivatives of curcumin were synthesized to restore the effectiveness of fluconazole (FLC) against FLC-resistant Candida spp. and structure-activity relationships were then discussed. Some novel derivatives showed promising features as novel antifungal lead compounds. Of them, compound 4 showed good alone or synergistic antifungal activity against FLC-resistant Candida spp. Moreover, compound 4 was proven as a potent inhibitor of Candida albicans biofilm formation and yeast-to-hypha morphological transition whether used alone or in combination with FLC, which was further confirmed by the inhibitory effect on cellular surface hydrophobicity of C. albicans. Compound 4 also inhibits intracellular ATP production of C. albicans and disrupts membrane permeability of C. albicans when used in combination with FLC. The results highlighted the potential of curcumin derivatives to overcome fluconazole-related and biofilm-related drug resistance.

The Neosartorya fischeri Antifungal Protein 2 (NFAP2): A New Potential Weapon against Multidrug-Resistant Candida auris Biofilms.

Candida auris is a potential multidrug-resistant pathogen able to persist on indwelling devices as a biofilm, which serve as a source of catheter-associated infections. Neosartorya fischeri antifungal protein 2 (NFAP2) is a cysteine-rich, cationic protein with potent anti-Candida activity. We studied the in vitro activity of NFAP2 alone and in combination with fluconazole, amphotericin B, anidulafungin, caspofungin, and micafungin against C. auris biofilms. The nature of interactions was assessed utilizing the fractional inhibitory concentration index (FICI), a Bliss independence model, and LIVE/DEAD viability assay. NFAP2 exerted synergy with all tested antifungals with FICIs ranging between 0.312-0.5, 0.155-0.5, 0.037-0.375, 0.064-0.375, and 0.064-0.375 for fluconazole, amphotericin B, anidulafungin, caspofungin, and micafungin, respectively. These results were confirmed using a Bliss model, where NFAP2 produced 17.54 µM2%, 2.16 µM2%, 33.31 µM2%, 10.72 µM2%, and 111.19 µM2% cumulative synergy log volume in combination with fluconazole, amphotericin B, anidulafungin, caspofungin, and micafungin, respectively. In addition, biofilms exposed to echinocandins (32 mg/L) showed significant cell death in the presence of NFAP2 (128 mg/L). Our study shows that NFAP2 displays strong potential as a novel antifungal compound in alternative therapies to combat C. auris biofilms.

"Clinical Aspects of Chronic Granulomatous Disease in Upper Egypt".

Chronic granulomatous disease (CGD) is a rare inherited primary immunodeficiency disorder that affects phagocytes and is characterized by a marked increased susceptibility to severe bacterial and fungal infections. We aimed to describe the clinical presentations of pediatric patients with CGD in Upper Egypt and to identify the defective component of NADPH oxidase. Pediatric patients diagnosed with CGD within one year from January 2018 to January 2019 were enrolled in the study. Patient history, clinical and laboratory investigations were carried out, including nitroblue tetrazolium test and flow cytometry DHR analysis. Infectious microorganisms were isolated from infected sites to identify the causative agents and their resistance profile. A total of 15 patients were diagnosed with CGD. Failure to thrive and lymphadenopathy were the most common presentations. The median age of clinical onset was 1.17 years of age. The most common gene mutations were observed in the CYBA gene. All cases showed pulmonary infections followed by abscesses. Staphylococcus aureus and Klebsiella pneumoniae were the most frequently isolated bacterial pathogens, Aspergillus spp and Candida spp were isolated from fungal infections. 4/15 (26.7%) children died due to severe serious infections. We concluded that CGD is common in Upper Egypt, and we recommend raising the awareness and testing for CGD in pediatric patients with recurrent or persistent infections, especially those with a familiar history of similar manifestations to avoid delays in proper diagnosis and deterioration of cases. Abbreviations: CGD: chronic granulomatous disease; XL: X-linked; AR: autosomal recessive.

Fruit host-dependent fungal communities in the microbiome of wild Queensland fruit fly larvae.

Bactrocera tryoni (Froggatt), the Queensland fruit fly (Qfly), is a highly polyphagous tephritid fly that is widespread in Eastern Australia. Qfly physiology is closely linked with its fungal associates, with particular relationship between Qfly nutrition and yeast or yeast-like fungi. Despite animal-associated fungi typically occurring in multi-species communities, Qfly studies have predominately involved the culture and characterisation of single fungal isolates. Further, only two studies have investigated the fungal communities associated with Qfly, and both have used culture-dependant techniques that overlook non-culturable fungi and hence under-represent, and provide a biased interpretation of, the overall fungal community. In order to explore a potentially hidden fungal diversity and complexity within the Qfly mycobiome, we used culture-independent, high-throughput Illumina sequencing techniques to comprehensively, and holistically characterized the fungal community of Qfly larvae and overcome the culture bias. We collected larvae from a range of fruit hosts along the east coast of Australia, and all had a mycobiome dominated by ascomycetes. The most abundant fungal taxa belonged to the genera Pichia (43%), Candida (20%), Hanseniaspora (10%), Zygosaccharomyces (11%) and Penicillium (7%). We also characterized the fungal communities of fruit hosts, and found a strong degree of overlap between larvae and fruit host communities, suggesting that these communities are intimately inter-connected. Our data suggests that larval fungal communities are acquired from surrounding fruit flesh. It is likely that the physiological benefits of Qfly exposure to fungal communities is primarily due to consumption of these fungi, not through syntrophy/symbiosis between fungi and insect 'host'.

Impact of biofilm production by Candida species and antifungal therapy on mortality of patients with candidemia.

BACKGROUND AND OBJECTIVES: Few studies have investigated the clinical outcomes of patients with candidemia caused by Candida species with different levels of biofilm formation. We aimed to investigate the impact of antifungal therapy on the outcome of candidemia caused by Candida species that were categorised as low biofilm formers (LBFs), moderate biofilm formers (MBFs), and high biofilm formers (HBFs). METHODS: Adults with candidemia caused by LBF and HBF/MBF Candida species that were susceptible to fluconazole and caspofungin were included to investigate the impact of treatment with fluconazole vs an echinocandin on 30-day crude mortality. RESULTS: In total, 215 patients with candidemia received fluconazole and 116 patients received an echinocandin. In multivariate analysis, Pittsburgh bacteremia score ≥ 4 (adjusted odds ratio [AOR] =2.42; 95% confidence interval [CI], 1.32-4.41), malignancy (AOR = 3.45; 95% CI, 1.83-6.51), not removing the central venous catheter within 48 hours of a positive blood culture (AOR = 4.69; 95% CI, 2.61-8.45), and treatment with fluconazole for candidemia due to HBF/MBF Candida spp. (AOR = 2.23; 95% CI, 1.22-4.06) were independent factors associated with 30-day mortality. Of the 165 patients infected by HBF/MBF Candida isolates, those who received azole therapy had a significantly higher sepsis-related mortality rate than those who received echinocandin therapy (44.9% [49/109] vs 26.8% [15/56], P = .03). CONCLUSIONS: There was a trend of an independent association between fluconazole treatment and poor outcomes in the patients infected by HBF/MBF Candida strains.

Case report: nosocomial fungemia caused by Candida diddensiae.

BACKGROUND: Candida diddensiae, a yeast found in olive oil, is considered non-pathogenic to humans. Here, we describe the first case of fungemia caused by C. diddensiae in a hospitalized patient with underlying diseases. CASE PRESENTATION: A 62-year-old woman was admitted because of multiple contusions due to repeated falls and generalized weakness. She presented with chronic leukopenia due to systemic lupus erythematosus, and multiple cranial nerve neuropathies due to a recurring chordoma. She was given a lipid emulsion containing total parenteral nutrition (TPN) starting on the day of admission. Broad-spectrum antibiotics had been administered during her last hospital stay and from day 8 of this hospitalization. However, no central venous catheter was used during this hospital stay. Blood cultures obtained on hospital days 17, 23, and 24 yielded the same yeast, which was identified as C. diddensiae via sequence analyses of the internal transcribed spacer region and D1/D2 regions of the 26S ribosomal DNA of the rRNA gene. In vitro susceptibility testing showed that the minimum inhibitory concentration of fluconazole for all isolates was 8 µg/mL. On day 23, TPN was discontinued and fluconazole therapy was started. Blood cultures obtained on day 26 were negative. The fluconazole therapy was replaced with micafungin on day 26 and the patient exhibited improvements. CONCLUSION: The use of lipid TPN may potentially contribute to the occurrence of nosocomial fungemia by C. diddensiae, an unusual Candida species.

A 16-year retrospective study on fungal prevalence and diversity in patients with cystic fibrosis: Candida dubliniensis was associated with a decline in lung function.

OBJECTIVES: To study the prevalence of fungal species in cystic fibrosis (CF) patients over a 16 years period. To examine the impact of Candida albicans (C. albicans), Candida dubliniensis (C. dubliniensis) and Aspergillus fumigatus (A. fumigatus) on lung function. METHODS: Observational single-center cohort study (2000-2015) including 133 CF patients (ages 6-66 years). Linear mixed models with autoregressive covariance matrix were used. RESULTS: The most common fungus was C. albicans (prevalence 62%) followed by A. fumigatus (22%) and C. dubliniensis (11%). In the initial year of detection, there was no impact of C. albicans, C. dubliniensis or A. fumigatus on lung function. However, one and two years after detection of C. dubliniensis a reduction in percent predicted forced expiratory volume in the first second (ppFEV1) was observed of 3.8% (p = 0.022) and 4.1% (p = 0.017), respectively, compared with CF patients without these findings. Furthermore, patients with positive cultures for any of these fungal species for three consecutive years exhibited a decline in lung function: C. dubliniensis, 7.6% reduction in ppFEV1 (p = 0.001); A. fumigatus, 4.9% (p = 0.007); C. albicans, 2.6% (p = 0.014). The results were adjusted for age, CFTR genotype, chronic and intermittent P. aeruginosa colonization, and numbers of intravenous antibiotic treatments per year. Persistence of C. dubliniensis for three consecutive years was positively correlated to age and erythrocyte sedimentation rate (ESR) (both p = 0.001). CONCLUSIONS: Cystic fibrosis patients who were cultured positive for C. dubliniensis, C. albicans or A. fumigatus in sputum exhibited a decline in ppFEV1 over time. The effect was most pronounced for C. dubliniensis.

Anticandidal and synergistic effect of essential oil fractions from three aromatic plants used in Cameroon.

Despite the use of conventional antifungal drugs, Candida spp resistance, especially mediated by biofilms formation remains recurrent. Therefore, new drugs to treat fungal infections are urgently needed. In this line, our study aimed to determine the anticandidal activity and the synergistic effect of essential oil fractions from Syzygium aromaticum, Cymbopogon citratus and Aeollanthus heliotropioides harvested in Cameroon using a combination approach. Essential oils have been obtained by hydrodistillation and their chemical composition was analysed by GC/MS. Antifungal activity was evaluated by the determination of minimum inhibitory concentration (MIC) using a micro-dilution method. The sorbitol and ergosterol binding ability and anti-biofilm activity were also assessed in order to evaluate the mode of action. The crude essential oils showed a good anticandidal activity, most probably due to the eugenol, linalool and citral content. The combination of two fractions F7 and F10 showed an improved growth inhibition of Candida spp compared to the crude essential oils. The inhibitory effect could be related with the presence of γ-dodecalactone and citronellol as main compounds. The best synergistic combination F7F10 inhibited biofilm formation at ten time reduced combination MIC. The active fractions targeted different fungal cell structures, including cell wall and membrane. Our study showed that the combination of selected essential oils fractions exhibited an increased antifungal activity against Candida spp compared to the crude essential oils. The combination approach of inner compound groups may be used as a promising strategy for the development of efficient recombined micro-essential oils as antifungal agents to face Candida resistance.

Respiratory mycobiome and suggestion of inter-kingdom network during acute pulmonary exacerbation in cystic fibrosis.

Lung infections play a critical role in cystic fibrosis (CF) pathogenesis. CF respiratory tract is now considered to be a polymicrobial niche and advances in high-throughput sequencing allowed to analyze its microbiota and mycobiota. However, no NGS studies until now have characterized both communities during CF pulmonary exacerbation (CFPE). Thirty-three sputa isolated from patients with and without CFPE were used for metagenomic high-throughput sequencing targeting 16S and ITS2 regions of bacterial and fungal rRNA. We built inter-kingdom network and adapted Phy-Lasso method to highlight correlations in compositional data. The decline in respiratory function was associated with a decrease in bacterial diversity. The inter-kingdom network revealed three main clusters organized around Aspergillus, Candida, and Scedosporium genera. Using Phy-Lasso method, we identified Aspergillus and Malassezia as relevantly associated with CFPE, and Scedosporium plus Pseudomonas with a decline in lung function. We corroborated in vitro the cross-domain interactions between Aspergillus and Streptococcus predicted by the correlation network. For the first time, we included documented mycobiome data into a version of the ecological Climax/Attack model that opens new lines of thoughts about the physiopathology of CF lung disease and future perspectives to improve its therapeutic management.

Exploring the role of oral microorganisms in the pathogenesis of mucositis by assessing their impact on metabolic activity and reproductive capacity of epithelial cells in vitro.

PURPOSE: Clinical and in vitro studies showed selected oral microorganisms to be related to delayed wound healing and ulcerative oral mucositis. However, it is not known whether this effect is due to reduced metabolism and/or the reduced reproductive capacity of epithelial cells. Therefore, we studied the influence of the oral microorganisms Porphyromonas gingivalis, Candida glabrata, and Candida kefyr on cell metabolism and reproductive capacity of oral epithelial cells, aimed to further unravel the pathogenesis of oral mucositis. METHODS: Oral epithelial cells were exposed to different concentrations of P. gingivalis, C. glabrata, and C. kefyr as mono-infections or mixed together. An MTT assay was performed to determine the effect on cell metabolism. A clonogenic assay was used to study the effect on the reproductive capacity of oral epithelial cells. RESULTS: The metabolism of oral epithelial cells was reduced when the microorganisms were present in high concentrations: P. gingivalis at a multiplicity of infection (MOI) of 1000 and the Candida spp. at MOI 100. No statistical difference was observed in the ability of a single epithelial cell to grow into a colony of cells between control and P. gingivalis, C. glabrata, and C. kefyr, independent of the concentrations and combinations used. CONCLUSION: P. gingivalis, C. glabrata, and C. kefyr lowered the metabolic activity of oral epithelial cells in high concentrations, yet they did not influence the reproductive capacity of epithelial cells. Their impact on ulcerative oral mucositis is likely due to an effect on the migration, proliferation, and metabolism of epithelial cells.

Anti-inflammatory and anti-Candida Effects of Brazilian Organic Propolis, a Promising Source of Bioactive Molecules and Functional Food.

Brazilian organic propolis (BOP) is an unexplored Brazilian propolis that is produced organically and certified according to international legislation. Our results showed that BOP has strong anti-inflammatory effects and acts by reducing nuclear factor κB activation, tumor necrosis factor α release, and neutrophil migration. In addition, BOP6 exhibited antifungal activity on planktonic and biofilm cultures of Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei, and Candida parapsisolis and reduced in vitro yeast cell adhesion to human keratinocytes at sub-inhibitory concentrations. BOP demonstrated significantly low toxicity in Galleria melonella larvae at antifungal doses. Lastly, a chemical analysis revealed the presence of caffeoyltartaric acid, 3,4-dicaffeoylquinic acid, quercetin, and gibberellins A7, A9, and A20, which may be responsible for the biological properties observed. Thus, our data indicate that BOP is a promising source of anti-inflammatory and antifungal molecules that may be used as a functional food.

Surveillance study of the prevalence, species distribution, antifungal susceptibility, risk factors and mortality of invasive candidiasis in a tertiary teaching hospital in Southwest China.

BACKGROUND: Invasive candidiasis (IC) is the most common invasive fungal infection. The epidemiology of IC in hospitalized patients has been widely investigated in many metropolitan cities; however, little information from medium and small cities is known. METHODS: A 5-year retrospective study was carried out to analyze the prevalence, species distribution, antifungal susceptibility, risk factors and mortality of inpatients with invasive Candida infection in a regional tertiary teaching hospital in Southwest China. RESULTS: A total of 243 inpatients with invasive Candida infection during the five-year study period were identified, with a mean annual incidence of 0.41 cases per 1000 admissions and a 30-day mortality rate of 12.3%. The species distributions of Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei, Candida parapsilosis and other Candida species was 45.3, 30.0, 15.2, 4.9, 2.1 and 2.5%, respectively. The total resistance rates of fluconazole (FCA), itraconazole (ITR) and voriconazole (VRC) were 18.6, 23.1 and 18.5%, respectively. Respiratory dysfunction, pulmonary infection, cardiovascular disease, chronic/acute renal failure, mechanical ventilation, abdominal surgery, intensive care in adults, septic shock and IC due to C. albicans were associated with 30-day mortality (P < 0.05) according to the univariate analyses. Respiratory dysfunction [odds ratio (OR), 9.80; 95% confidence interval (CI), 3.24-29.63; P < 0.001] and IC due to C. albicans (OR, 3.35; 95% CI, 1.13-9.92; P = 0.029) were the independent predictors of 30-day mortality. CONCLUSIONS: This report shows that the incidence and mortality rates are lower and that the resistance rates to azoles are higher in medium and small cities than in large cities and that the species distributions and risk factors in medium and small cities are different from those in large cities in China. It is necessary to conduct epidemiological surveillance in medium and small cities to provide reference data for the surveillance of inpatients with IC infections.

Candida-Bacterial Biofilms and Host-Microbe Interactions in Oral Diseases.

Oral cavity harbors a complex and highly diverse microbial community. Cross-kingdom interactions between Candida and oral bacteria are critical for their co-existence, which may also affect the course and the severity of biofilm-mediated bacterial-mediated diseases. C. albicans has been found in polymicrobial biofilms associated with denture stomatitis, oral mucositis, dental caries, periodontal diseases, peri-implantitis, and root canal infection. Thus, it is of utmost importance to unravel the mechanisms of Candida-bacterial interactions and their impact on the onset and severity of cross-kingdom biofilm-related diseases. Here, we highlight the potential role of Candida-bacterial biofilm interactions in the pathogenesis of oral diseases, especially mucosal infections and dental caries. The influence of Candida-bacterial biofilms on the mucosal host immune response is also discussed. Finally, we present some of the current and prospective therapeutic strategies for controlling these cross-kingdom interactions and their virulence properties associated with oral diseases.

Broad-spectrum antifungal activity of spirooxindolo-pyrrolidine tethered indole/imidazole hybrid heterocycles against fungal pathogens.

Invasive fungal infections are one of the leading causes of nosocomial bloodstream infections with a limited treatment option. A series of derivatized spirooxindolo-pyrrolidine tethered indole and imidazole heterocyclic hybrids have been synthesized, and their antifungal activity against fungal strains were determined. Here we characterize the antifungal activity of a specific spirooxindolo-pyrrolidine hybrid, dubbed compound 9c, a spirooxindolo-pyrrolidine tethered imidazole synthesized with a 2-chloro and trifluoromethoxy substituent. The compound 9c exhibited no cytotoxicity against mammalian cell line at concentrations that inhibited fungal strains. Compound 9c also significantly inhibited the fungal hyphae and biofilm formation. Our results indicate that spirooxindolo-pyrrolidine heterocyclic hybrids potentially represent a broad class of chemical agents with promising antifungal potential.

Spectrum of Trained Innate Immunity Induced by Low-Virulence Candida Species against Lethal Polymicrobial Intra-abdominal Infection.

Polymicrobial intra-abdominal infections (IAI) are clinically prevalent and cause significant morbidity and mortality, especially those involving fungi. Our laboratory developed a mouse model of polymicrobial IAI and demonstrated that coinfection with Candida albicans and Staphylococcus aureus (C. albicans/S. aureus) results in 80 to 90% mortality in 48 to 72 h due to robust local and systemic inflammation. Surprisingly, inoculation with Candida dubliniensis and S. aureus resulted in minimal mortality, and rechallenge of mice with lethal C. albicans/S. aureus conferred >90% protection up to 60 days postinoculation. Protection was mediated by Gr-1+ polymorphonuclear leukocytes, indicating a novel form of trained innate immunity (TII). The purpose of this study was to determine the microbial requirements and spectrum of innate-mediated protection. In addition to Candida dubliniensis, several other low-virulence Candida species (C. glabrata, C. auris, and C. albicansefg1Δ/Δ cph1Δ/Δ) and Saccharomyces cerevisiae conferred significant protection with or without S. aureus For C. dubliniensis-mediated protection, hyphal formation was not required, with protection conferred as early as 7 days after primary challenge but not at 120 days, and also following multiple lethal C. albicans/S. aureus rechallenges. This protection also extended to a lethal intravenous (i.v.) C. albicans challenge but had no effect in the C. albicans vaginitis model. Finally, studies revealed the ability of the low-virulence Candida species that conferred protection to invade the bone marrow by 24 h post-primary challenge, with a positive correlation between femoral bone marrow fungal infiltration at 48 h and protection upon rechallenge. These results support and further extend the characterization of this novel TII in protection against lethal fungal-bacterial IAI and sepsis.