Role of oral candidiasis in TB and HIV co-infection: AIDS Clinical Trial Group Protocol A5253

OBJECTIVE

To evaluate the association between oral candidiasis and tuberculosis (TB) in human immunodeficiency virus (HIV) infected individuals in sub-Saharan Africa, and to investigate oral candidiasis as a potential tool for TB case finding.

METHODS

Protocol A5253 was a cross-sectional study designed to improve the diagnosis of pulmonary TB in HIV-infected adults in high TB prevalence countries. Participants received an oral examination to detect oral candidiasis. We estimated the association between TB disease and oral candidiasis using logistic regression, and sensitivity, specificity and predictive values.

RESULTS

Of 454 participants with TB culture results enrolled in African sites, the median age was 33 years, 71% were female and the median CD4 count was 257 cells/mm(3). Fifty-four (12%) had TB disease; the prevalence of oral candidiasis was significantly higher among TB cases (35%) than among non-TB cases (16%, P < 0.001). The odds of having TB was 2.4 times higher among those with oral candidiasis when controlling for CD4 count and antifungals (95%CI 1.2-4.7, P = 0.01). The sensitivity of oral candidiasis as a predictor of TB was 35% (95%CI 22-48) and the specificity 85% (95%CI 81-88).

CONCLUSION

We found a strong association between oral candidiasis and TB disease, independent of CD4 count, suggesting that in resource-limited settings, oral candidiasis may provide clinical evidence for increased risk of TB and contribute to TB case finding.

Oral mycobiome analysis of HIV-infected patients: identification of Pichia as an antagonist of opportunistic fungi

Oral microbiota contribute to health and disease, and their disruption may influence the course of oral diseases. Here, we used pyrosequencing to characterize the oral bacteriome and mycobiome of 12 HIV-infected patients and matched 12 uninfected controls. The number of bacterial and fungal genera in individuals ranged between 8-14 and 1-9, among uninfected and HIV-infected participants, respectively. The core oral bacteriome (COB) comprised 14 genera, of which 13 were common between the two groups. In contrast, the core oral mycobiome (COM) differed between HIV-infected and uninfected individuals, with Candida being the predominant fungus in both groups. Among Candida species, C. albicans was the most common (58% in uninfected and 83% in HIV-infected participants). Furthermore, 15 and 12 bacteria-fungi pairs were correlated significantly within uninfected and HIV-infected groups, respectively. Increase in Candida colonization was associated with a concomitant decrease in the abundance of Pichia, suggesting antagonism. We found that Pichia spent medium (PSM) inhibited growth of Candida, Aspergillus and Fusarium. Moreover, Pichia cells and PSM inhibited Candida biofilms (P = .002 and .02, respectively, compared to untreated controls). The mechanism by which Pichia inhibited Candida involved nutrient limitation, and modulation of growth and virulence factors. Finally, in an experimental murine model of oral candidiasis, we demonstrated that mice treated with PSM exhibited significantly lower infection score (P = .011) and fungal burden (P = .04) compared to untreated mice. Moreover, tongues of PSM-treated mice had few hyphae and intact epithelium, while vehicle- and nystatin-treated mice exhibited extensive fungal invasion of tissue with epithelial disruption. These results showed that PSM was efficacious against oral candidiasis in vitro and in vivo. The inhibitory activity of PSM was associated with secretory protein/s. Our findings provide the first evidence of interaction among members of the oral mycobiota, and identifies a potential novel antifungal.

Animal models to investigate fungal biofilm formation

Microbial biofilms play an essential role in several infectious diseases and are defined as extensive communities of sessile organisms irreversibly associated with a surface, encased within a polysaccharide-rich extracellular matrix (ECM), and exhibiting enhanced resistance to antimicrobial drugs. Forming a biofilm provides the microbes protection from environmental stresses due to contaminants, nutritional depletion, or imbalances, but is dangerous to human health due to their inherent robustness and elevated resistance.The use of indwelling medical devices (e.g., central venous catheters, CVCs) in current therapeutic practice is associated with 80-90 % of hospital-acquired bloodstream and deep tissue infections. Most cases of catheter-related bloodstream infections (CRBSIs) involve colonization of microorganisms on catheter surfaces where they form a biofilm. Additionally, Fusarium solani and F. oxysporum were the causative organisms of the 2005/2006 outbreak of contact lens-associated fungal keratitis in the United States, Europe, the UK, and Singapore, and these infections involved formation of biofilms on contact lens. Fungal biofilm formation is studied using a number of techniques, involving the use of a wide variety of substrates and growth conditions. In vitro techniques involving the use of confocal scanning laser/scanning electron microscopy, metabolic activity assay, dry weight measurements, and antifungal susceptibility assays are increasingly used by investigators to quantify and evaluate biofilm morphology. However, there are not many in vivo models used to validate biofilm-associated infections. In this protocol, we describe a clinically relevant rabbit model of C. albicans biofilm-associated catheter infection to evaluate the morphology, topography, and architecture of fungal biofilms. We also describe a murine model of contact lens-associated Fusarium keratitis.Evaluation of the formation of fungal biofilms on catheters in vivo, their analysis using scanning electron microscopy (SEM) and quantitative catheter culture (QCC), and treatment of biofilms using antimicrobial lock therapy can be completed in ~20-25 days using the described methods. The rabbit model has utility in evaluating the efficacy of lock solutions. In addition, the murine model of contact lens-associated Fusarium keratitis enables characterizing/comparing the formation of Fusarium biofilms on contact lenses in vitro and determining their role in vivo.

Human Hyalohyphomycoses: A Review of Human Infections Due toAcremoniumspp.,Paecilomycesspp.,Penicilliumspp., andScopulariopsisspp

Human infections due to opportunistic molds are on the rise. This is due to recent advances in medical technology that have led to increased numbers of patients who are immunosuppressed, receiving broad-spectrum antibiotics, or have indwelling medical devices. In this article, human infections caused by four hyalohyphomycoses, Acremonium spp., Paecilomyces spp., Penicillium spp., and Scopulariopsis spp., will be reviewed. Specific areas of focus will include the epidemiology, mycology, clinical presentations, and treatment options for each of these four hyaline molds.

The RodA hydrophobin on Aspergillus fumigatus spores masks dectin-1- and dectin-2-dependent responses and enhances fungal survival in vivo

Aspergillus and Fusarium species are important causes of fungal infections worldwide. Airborne spores (conidia) of these filamentous fungi express a surface protein that confers hydrophobicity (hydrophobin) and covers cell wall components that would otherwise induce a host immune cell response. Using a mutant Aspergillus fumigatus strain (ΔrodA) that does not express the RodA hydrophobin, and Aspergillus and Fusarium conidia from clinical isolates that were treated with hydrofluoric acid (which removes the A. fumigatus RodA protein), we observed increased surface exposure of β1,3-glucan and α-mannose on Aspergillus and Fusarium conidia. We also found that ΔrodA and hydrofluoric acid-treated conidia stimulate significantly higher NF-κB p65 nuclear translocation and cytokine production by macrophages from C57BL/6, but not from Dectin-1(-/-) or Dectin-2(-/-) mice. Using a murine model of A. fumigatus corneal infection, we showed that ΔrodA conidia induced significantly higher cytokine production, neutrophil infiltration, and more rapid fungal clearance from C57BL/6 corneas compared with the parent G10 strain, which was dependent on Dectin-1 and Dectin-2. Together, these findings identify the hydrophobin RodA as a virulence factor that masks Dectin-1 and Dectin-2 recognition of conidia, resulting in impaired neutrophil recruitment to the cornea and increased fungal survival and clinical disease.

Evaluation of Antifungal Efficacy in an Optimized Animal Model ofTrichophytonmentagrophytes-Dermatophytosis

Dermatophytoses are known to cause considerable discomfort, cosmetic problems and financial loss that have been recognized as a significant health concern worldwide. Since currently available antifungal agents have limitations in their efficacy, new agents are being developed. This study was undertaken to optimize an in vivo model of experimental dermatophytosis for evaluation of the efficacy of antifungal compounds. Guinea pigs were infected with different inocula of T. mentagrophytes to establish dermatophytosis. The optimal conditions for dermatophytosis in guinea pigs were found to be an inoculum size of 1 x 10(7) fungal cells applied on abraded skin. After optimization, animals were treated with oral or topical formulations of terbinafine. The optimized guinea pig model was found to be highly reproducible, and useful in the primary screening and evaluation of the anti-dermatophytic efficacy of topical and oral formulations of antifungal agents.

Optimization of an infected shoe model for the evaluation of an ultraviolet shoe sanitizer device

BACKGROUND

Onychomycosis and tinea pedis (athlete's foot) are infections of the nails and skin caused by pathogenic fungi collectively known as dermatophytes. These infections are difficult to treat, and patients often relapse; it is thought that a patient's footwear becomes infected with these fungal organisms and, thus, is an important reservoir for reinfection. Therefore, it is important to find an effective means for killing the dermatophytes that may have colonized the inner surface of the shoes of patients with superficial fungal infections. In this study, we developed an in vitro model for culturing dermatophytes in footwear and used this model to evaluate the effectiveness of a commercial ultraviolet shoe sanitizer in eradicating the fungal elements residing in shoes.

METHODS

Leather and athletic shoes (24 pairs) were inoculated with either Trichophyton rubrum or Trichophyton mentagrophytes (10(7) colony-forming units/mL) strains and were placed at 35°C for 4 to 5 days. Next, we compared the ability of swabbing versus scraping to collect microorganisms from infected shoes. Following the optimized method, shoes were infected and were irradiated with one to three cycles of radiation. The inner surfaces of the shoes were swabbed or scraped, and the specimens were cultured for dermatophyte colony-forming units.

RESULTS

Leather and canvas shoes were infected to the same extent. Moreover, scraping with a scalpel was overall more effective than was swabbing with a cotton-tipped applicator in recovering viable fungal elements. Irradiation of shoes with one, two, or three cycles resulted in reduction of fungal colonization to the same extent.

CONCLUSIONS

The developed infected shoe model is useful for assessing the effectiveness of ultraviolet shoe sanitizers. Also, ultraviolet treatment of shoes with a commercial ultraviolet C sanitizing device was effective in reducing the fungal burden in shoes. These findings have implications regarding breaking foot infection cycles.

Molecular analysis of dermatophytes suggests spread of infection among household members

Dermatophyte infection from the same strains may be an important route for transmission of dermatophytoses within a household. In this study, we used molecular methods to identify dermatophytes in members of dermatophyte-infected households and evaluated variables associated with the spread of infection. Fungal species were identified by polymerase chain reaction (PCR) using primers targeting the internal transcribed spacer (ITS) regions (ITS1 and ITS4). For strain differentiation, fungal DNA was probed with a ribosomal DNA-specific probe (containing ITS1, 5.8S ribosomal DNA, and ITS2) to detect restriction fragment length polymorphisms (RFLPs). Associations between the spread of a dermatophyte infection and fungal/host variables were determined using χ² and logistic regression analyses. Among the 50 households enrolled in this study, 18 included multiple infected members (MIMs). Trichophyton rubrum was the most commonly isolated dermatophyte species, followed by Trichophyton mentagrophyts and Epidermophyton floccosum. Sixteen T rubrum strains (TR-A to TR-P) were identified, with spread of infection detected in 8 MIM households. Factors that were significantly (P<.05) associated with the spread of infection included the presence of strains TR-B or TR-D, a history of concomitant tinea pedis and onychomycosis, and plantar scaling and/or nail discoloration. This study is unique in that it used molecular evidence to demonstrate the association of certain strains with the spread of dermatophyte infection among members of the same household.

Metabolomics reveals differential levels of oral metabolites in HIV-infected patients: toward novel diagnostic targets

The objective of the current study was to characterize the profile of oral metabolites in HIV-infected patients using metabolomics. Oral wash samples were collected from 12 HIV-infected and 12 healthy individuals (matched for age, sex, and ethnicity), processed, and analyzed by metabolomics. We detected 198 identifiable and 85 nonidentifiable metabolites; 27 identifiable metabolites were differentially present (12 increased, 15 decreased) in HIV-infected patients. Elevated metabolites included p-cresol sulfate, nucleotides (e.g., allantoin), and amino acids (e.g., phenylalanine, tryptophan), whereas decreased oral metabolites included fucose, fumarate, and N-acetylglucosamine. Pathway network analysis revealed the largest multinode network in healthy versus HIV-infected patients to involve carbohydrate biosynthesis and degradation. HIV-infected patients on antiretroviral therapy (ART) showed the largest number (12) of statistically significant metabolite correlation differences compared with healthy controls. Interestingly, the oral phenlyalanine:tyrosine ratio increased in ART-naive HIV-infected patients (mean ± SEM = 2.58 ± 0.87) compared with healthy individuals (1.33 ± 0.10, p = 0.062) or ART-experienced patients (1.78 ± 0.30, p = 0.441). This is the first study to reveal differential levels of oral metabolites in HIV-infected patients compared withj healthy volunteers, and that oral phenlyalanine:tyrosine ratio may be a useful marker for noninvasive monitoring of the immune status during HIV infection.

Echinocandins: are they all the same?

The discovery of echinocandins, and their development and approval, was hailed as a significant addition to our antifungal armamentarium, previously predominated by polyenes and azoles. To date, three echinocandins (anidulafungin, caspofungin, and micafungin) have been approved by the U.S. Food and Drug Administration for the treatment of fungal infections. Since all three echinocandins target the fungal cell wall and share a similar structural chemical backbone, they are perceived to be identical. However, a scientific literature review shows distinct differences among the echinocandins in terms of in vitro activity, fungicidal activity, post-antifungal effect, paradoxical effect, and activity on biofilms. More investigation is warranted to determine if the observed differences among the echinocandins can translate to clinical advantages.

Characterization of fusarium keratitis outbreak isolates: contribution of biofilms to antimicrobial resistance and pathogenesis

PURPOSE

Fusarium is a major cause of microbial keratitis, and its ability to form biofilms was suggested as a contributing factor in recent outbreaks. We investigated the ability of outbreak Fusarium isolates (F. solani species complex [FSSC] and F. oxysporum species complex [FOSC]) to form biofilms in vitro and in vivo, and evaluated their antifungal susceptibilities.

METHODS

Biofilm formation was assessed using our in vitro contact lens model and in vivo murine model. Biofilm architecture was assessed using confocal laser scanning microscopy (CLSM). Susceptibility against amphotericin B (AmB), voriconazole (VCZ), and natamycin (NAT) was determined using the CLSI-M38-A2 method and XTT metabolic assay.

RESULTS

FSSC strains formed more biofilms than FOSC, in a strain- and clade-dependent manner. CLSM analyses revealed that "high biofilm forming" (HBF) strains had denser and thicker biofilms than "low biofilm forming" (LBF) strains of both species (thickness 51 vs. 41 μm for FSSC and 61 vs. 45 μm for FOSC strains, P < 0.05 for both comparisons). Fusarium biofilms exhibited species-dependent antifungal susceptibilities (e.g., FSSC biofilms AmB minimal inhibitory concentrations [MIC] ≥16 μg/mL, while NAT or VCZ MICs were 2-8 μg/mL). FSSC-infected mice had severe corneal opacification independent of biofilm thickness, while FOSC infection resulted in moderate corneal opacification. Corneal fungal burden of mice infected with HBF strains was higher than those of the LBF strains. In contrast, the reference ATCC isolate was unable to cause infection.

CONCLUSIONS

The ability to form biofilms is a key pathogenicity determinant of Fusarium, irrespective of the thickness of these biofilms. Further studies are warranted to explore this association in greater detail.

Efficacy, safety and tolerability of topical terbinafine nail solution in patients with mild-to-moderate toenail onychomycosis: results from three randomized studies using double-blind vehicle-controlled and open-label active-controlled designs

BACKGROUND

Terbinafine nail solution (TNS) was developed for the treatment of onychomycosis.

OBJECTIVE

To assess the efficacy of TNS vs. vehicle and amorolfine 5% nail lacquer.

METHODS

Subjects with mild-to-moderate toe onychomycosis (25% to ≤75% nail-involvement, matrix uninvolved) were randomized to receive either TNS or vehicle in two double-blind studies, and to TNS or amorolfine in an active-controlled, open-label study. Primary endpoint was complete cure (no residual clinical involvement and negative mycology) at week 52. Secondary endpoints were mycological cure (negative mycology defined as negative KOH microscopy and negative culture) and clinical effectiveness (≤10% residual-involvement and negative mycology) at week 52.

RESULTS

Complete cure was not different between TNS vs. vehicle and amorolfine. Mycological cure was higher with TNS vs. vehicle, as was clinical effectiveness with TNS vs. vehicle, and TNS and amorolfine were not different for secondary efficacy endpoints. Patients achieving mycological cure had a better clinical outcome, and efficacy was improved in subjects with milder disease. Post hoc analysis suggests that nail thickness is an important prognostic factor. Moreover, mycological cure may require 6 months of treatment regimen while complete cure and clinical effectiveness may be achievable only after 10 months. A simulation study suggests that longer treatment duration would have resulted in higher complete cure with TNS vs. vehicle. Study treatments were well-tolerated.

CONCLUSION

Primary efficacy objectives were not met in the studies reported herein. Possible reasons for failure to achieve significant outcomes include insufficient length of treatment; stringency of primary endpoint and severity of nail involvement of study population.

Lipidomics of Candida albicans biofilms reveals phase-dependent production of phospholipid molecular classes and role for lipid rafts in biofilm formation

Candida albicans-associated bloodstream infections are linked to the ability of this yeast to form biofilms. In this study, we used lipidomics to compare the lipid profiles of C. albicans biofilms and planktonic cells, in early and mature developmental phases. Our results showed that significant differences exist in lipid composition in both developmental phases. Biofilms contained higher levels of phospholipid and sphingolipids than planktonic cells (nmol per g biomass, P<0.05 for all comparisons). In the early phase, levels of lipid in most classes were significantly higher in biofilms compared to planktonic cells (P≤0.05). The ratio of phosphatidylcholine to phosphatidylethanolamine was lower in biofilms compared to planktonic cells in both early (1.17 vs 2.52, P≤0.001) and late (2.34 vs 3.81, P≤0.001) developmental phases. The unsaturation index of phospholipids decreased with time, with this effect being particularly strong for biofilms. Inhibition of the biosynthetic pathway for sphingolipid [mannosyl diinositolphosphoryl ceramide, M(IP)₂C] by myriocin or aureobasidin A, and disruption of the gene encoding inositolphosphotransferase (Ipt1p), abrogated the ability of C. albicans to form biofilms. The differences in lipid profiles between biofilms and planktonic Candida cells may have important implications for the biology and antifungal resistance of biofilms.

Development of a 96-well catheter-based microdilution method to test antifungal susceptibility of Candida biofilms

BACKGROUND

Candida biofilms, which are often associated with device-related infections, including catheter-related bloodstream infections, are resistant to commonly used antifungal agents. Current microtitre (96-well) plate-based methods to determine the antifungal susceptibility of these biofilms do not involve clinically relevant substrates (e.g. catheters), and are not well suited for evaluating the surface topography and three-dimensional architecture of biofilms. We describe a simple, reproducible catheter-based microtitre plate method to form biofilms and evaluate their antifungal susceptibility.

METHODS

Biofilms were formed by Candida species on 5 mm catheter discs placed in microtitre plates and quantified using metabolic conversion of a formazan dye (XTT). The morphology, surface topography and three-dimensional architecture of these biofilms were evaluated by fluorescence, confocal scanning laser and scanning electron microscopy, respectively. The optimized XTT method was used to evaluate the antifungal susceptibility of formed Candida biofilms to fluconazole, voriconazole, itraconazole and anidulafungin.

RESULTS

Maximum XTT activity was achieved within 90 min. All tested Candida strains formed robust biofilms on catheter discs at both 24 and 48 h (P = 0.66). Biofilms exhibited typical gross morphology, surface topography and architecture, and no difference in biofilm thickness (P = 0.37). The three tested azoles were not active against the biofilms (MIC ≥ 64 mg/L), but anidulafungin possessed potent activity against them (MIC = 0.063-0.125 mg/L).

CONCLUSIONS

The developed method is simple, rapid and reproducible, and requires relatively small amounts of drug. It can be used to perform both high-resolution microscopic analysis of the topography and architecture of biofilms, and evaluation of their antifungal susceptibility.

A rabbit model for evaluation of catheter-associated fungal biofilms

Most cases of catheter-related bloodstream infections (CRBSIs) involve colonization of micro-organisms on catheter surfaces where they eventually become embedded in a biofilm. Fungal biofilm formation is studied using a number of techniques, involving the use of a wide variety of substrates and growth conditions. In vitro techniques involving use of confocal scanning laser/scanning electron microscopy, metabolic activity assay, dry weight measurements and antifungal susceptibility assays are increasingly used by investigators to quantify and evaluate biofilm morphology. However, there are not many in vivo models used to validate biofilm-associated infections. In this protocol, we describe clinically relevant rabbit model of C. albicans biofilm-associated catheter infection to evaluate the morphology, topography, and architecture of fungal biofilms. The methods described here can be completed in a typical laboratory setting. Evaluation of the formation of fungal biofilms on catheters in vivo, their analysis using scanning electron microscopy (SEM) and quantitative catheter culture (QCC) and treatment of biofilms using antimicrobial lock therapy can be completed using the described methods in ~20-25 days. This model has utility in evaluating the efficacy of lock solutions. In addition, it is a useful approach for characterizing/comparing the formation of biofilms by wild type and isogenic mutants including clinical isolates in vivo. This model can also be used for testing different biomaterials.

Photodynamic therapy with Pc 4 induces apoptosis of Candida albicans

The high prevalence of drug resistance necessitates the development of novel antifungal agents against infections caused by opportunistic fungal pathogens, such as Candida albicans. Elucidation of apoptosis in yeast-like fungi may provide a basis for future therapies. In mammalian cells, photodynamic therapy (PDT) has been demonstrated to generate reactive oxygen species, leading to immediate oxidative modifications of biological molecules and resulting in apoptotic cell death. In this report, we assess the in vitro cytotoxicity and mechanism of PDT, using the photosensitizer Pc 4, in planktonic C. albicans. Confocal image analysis confirmed that Pc 4 localizes to cytosolic organelles, including mitochondria. A colony formation assay showed that 1.0 μM Pc 4 followed by light at 2.0 J cm(-2) reduced cell survival by 4 logs. XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxyanilide) assay revealed that Pc 4-PDT impaired fungal metabolic activity, which was confirmed using the FUN-1 (2-chloro-4-[2,3-dihydro-3-methyl-(benzo-1,3-thiazol-2-yl)-methylidene]-1-phenylquinolinium iodide) fluorescence probe. Furthermore, we observed changes in nuclear morphology characteristic of apoptosis, which were substantiated by increased externalization of phosphatidylserine and DNA fragmentation following Pc 4-PDT. These data indicate that Pc 4-PDT can induce apoptosis in C. albicans. Therefore, a better understanding of the process will be helpful, as PDT may become a useful treatment option for candidiasis.

The prevention of biofilm colonization by multidrug-resistant pathogens that cause ventilator-associated pneumonia with antimicrobial-coated endotracheal tubes

Ventilator-associated pneumonia (VAP) continues to be the nosocomial infection associated with the highest mortality in critically ill patients. Since silver-coated endotracheal tubes (ETT) was shown in a multicenter prospective randomized trials to decrease the risk of VAP, we compared the efficacy of two antiseptic agents such as gardine- and gendine-coated ETTs with that of silver-coated ETTs in preventing biofilm. The ETTs were tested for their ability to prevent the biofilm formation of methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter cloacae, and Candida albicans. Scanning electron microscopy studies revealed a heavy biofilm on uncoated and silver-coated ETT but not on the gardine-coated ETT. The gardine and gendine ETTs completely inhibited the formation of biofilms by all organisms tested and were more effective in preventing biofilm growth than the silver ETTs (p < 0.001). The gardine- and gendine-coated ETTs were more durable against MRSA than either the silver-coated or uncoated ETTs for up to 2 weeks (p < 0.0001). We have therefore shown that gardine- and gendine-coated ETTs are superior to silver-coated ETTs in preventing biofilm. Future animal and clinical studies are warranted to determine whether the gardine- and gendine-coated ETTs can significantly reduce the risk of VAP.

Identification of gentian violet concentration that does not stain oral mucosa, possesses anti-candidal activity and is well tolerated

Gentian violet (GV) is recommended for initial treatment of oral candidiasis in HIV-infected patients in resource-limited settings. Currently GV is not used because of its staining effects. In this study, we investigated the staining capacity of three different concentrations of GV to determine a concentration that does not cause staining. The selected concentration that did not cause staining was evaluated for its physical stability and antifungal activity. Fifteen healthy participants were randomized to rinse twice daily for 14 days with one of three GV concentrations: 0.1%, 0.0085%, or 0.00165%. Oral examination and intra-oral photographs were performed at baseline and at the end of therapy. Participants responded to a questionnaire to assess adverse events. Antifungal activity was evaluated using the Clinical and Laboratory Standard Institute methodology. GV at a concentration of 0.00165% did not stain the oral mucosa and was well tolerated. GV at a concentration of 0.00165% was stable and possessed antifungal activity when stored at certain temperatures for different time periods. Gentian violet solution at the concentration of 0.00165% does not stain the oral mucosa, is stable and possesses potent antifungal activity.

Disruption of sphingolipid biosynthetic gene IPT1 reduces Candida albicans adhesion and prevents activation of human gingival epithelial cell innate immune defense

We demonstrated the effect of a Candida albicans sphingolipid biosynthetic gene, IPT1, on the interaction between gingival epithelial and Candida cells using monolayer cultures and engineered human oral mucosa tissue (EHOM). Disrupting the IPT1 gene greatly reduced Candida adhesion to gingival epithelial cells, compared to the wild-type and revertant strains. The yeasts adhesion to epithelial cells may activate toll-like receptors (TLRs). Cell response against Candida infection was thus investigated by evaluating TLR expression and antimicrobial peptide (AMP) production. The wild-type and revertant strains both activated TLR2, TLR4, TLR6, and TLR9 gene expression in the epithelial cells, whereas the Δipt1 mutant Candida strain had no effect on this expression. This finding was supported by an increased AMP expression (human β-defensin HBD-2 and HBD-3) in the EHOM tissue infected with the wild-type and revertant Candida strains, and a decreased expression in the Δipt1 mutant-infected model. HBD protein secretion confirmed the absence of any effect by the Δipt1 on epithelial cell innate defense. This is the first study to demonstrate that a disruption of the IPT1 gene affects Candida-host interaction, thus preventing TLR activation and β-defensin expression.

Distinct roles for Dectin-1 and TLR4 in the pathogenesis of Aspergillus fumigatus keratitis

Aspergillus species are a major worldwide cause of corneal ulcers, resulting in visual impairment and blindness in immunocompetent individuals. To enhance our understanding of the pathogenesis of Aspergillus keratitis, we developed a murine model in which red fluorescent protein (RFP)-expressing A. fumigatus (Af293.1RFP) conidia are injected into the corneal stroma, and disease progression and fungal survival are tracked over time. Using Mafia mice in which c-fms expressing macrophages and dendritic cells can be induced to undergo apoptosis, we demonstrated that the presence of resident corneal macrophages is essential for production of IL-1beta and CXCL1/KC, and for recruitment of neutrophils and mononuclear cells into the corneal stroma. We found that beta-glucan was highly expressed on germinating conidia and hyphae in the cornea stroma, and that both Dectin-1 and phospho-Syk were up-regulated in infected corneas. Additionally, we show that infected Dectin-1(-/-) corneas have impaired IL-1beta and CXCL1/KC production, resulting in diminished cellular infiltration and fungal clearance compared with control mice, especially during infection with clinical isolates expressing high beta-glucan. In contrast to Dectin 1(-/-) mice, cellular infiltration into infected TLR2(-/-), TLR4(-/-), and MD-2(-/-) mice corneas was unimpaired, indicating no role for these receptors in cell recruitment; however, fungal killing was significantly reduced in TLR4(-/-) mice, but not TLR2(-/-) or MD-2(-/-) mice. We also found that TRIF(-/-) and TIRAP(-/-) mice exhibited no fungal-killing defects, but that MyD88(-/-) and IL-1R1(-/-) mice were unable to regulate fungal growth. In conclusion, these data are consistent with a model in which beta-glucan on A.fumigatus germinating conidia activates Dectin-1 on corneal macrophages to produce IL-1beta, and CXCL1, which together with IL-1R1/MyD88-dependent activation, results in recruitment of neutrophils to the corneal stroma and TLR4-dependent fungal killing.