Mast cells (MCs), key innate immune sentinels at the host-environment interface, serve as primary responders to invading pathogens. However, their specific contribution to host defense against cutaneous Candida albicans (C. albicans) infection and their synergy with other immune and non-immune cells remain poorly understood. Here, we show that MCs accumulate locally in skin lesions of patients with cutaneous candidiasis. In mouse models, MC-deficient Kit[W-sh/W-sh] mice developed more severe infection than wild-type (WT) controls, and adoptive transfer of bone marrow-derived mast cells (BMMCs) restored antifungal capacity, establishing a critical protective role for MCs in cutaneous C. albicans infection. Mechanistically, MCs secrete IL-6 to drive antimicrobial peptide (AMP) production by keratinocytes (KCs). Reciprocally, KCs activate the non-canonical NF-κB (NF-κB2) pathway and release CXCL2, which signals through CXCR2 on MCs to further promote IL-6 secretion, establishing an NF-κB2-CXCL2-IL-6 amplification loop between the two cell types. Topical recombinant IL-6 enhanced KC-mediated antifungal activity and ameliorated cutaneous C. albicans infection in MC-deficient mice, underscoring the essential, non-redundant role of MC-derived IL-6 in this axis. Collectively, our findings reveal an MC-KC amplification loop centered on the NF-κB2-CXCL2-IL-6 axis that orchestrates cutaneous antifungal defense and identify new therapeutic targets for cutaneous fungal infection.

Scopulariopsis brevicaulis is an uncommon cause of fungal keratitis, usually occurring after ocular trauma, and is associated with therapeutic difficulties because of its limited susceptibility to antifungal agents. We report the case of a 48-year-old man who presented with pain, redness, and watering of the left eye for one month following injury by iron foreign body particles during welding. Ocular examination revealed a corneal ulcer with hypopyon and markedly reduced visual acuity (2/60). Initial microscopic evaluation was negative for fungal elements; however, fungal culture after extended incubation yielded growth of S. brevicaulis, identified based on colony characteristics and microscopic morphology. Imaging further demonstrated left-sided dacryoadenitis. The patient was treated conservatively with intensive topical natamycin and voriconazole, along with systemic ketoconazole and supportive topical antibiotics. This approach led to clinical improvement, although some degree of visual impairment persisted. This case highlights the importance of maintaining a high index of suspicion, allowing prolonged incubation of fungal cultures, and initiating timely targeted antifungal therapy in rare mould keratitis to achieve favorable outcomes and potentially avoid surgical intervention.

Ocular fungal diseases are associated with severe infection and pain and, in advanced stages, can lead to vision loss. Current treatment options are limited to the topical application of conventional drugs, and the bioavailability of these drugs is quite limited due to ocular barriers. In this study, a dual-drug nanodelivery system was developed to improve intraocular drug delivery by combining antifungal and anti-inflammatory therapies. Posaconazole (PSC), a broad-spectrum triazole antifungal agent, and dexketoprofen trometamol (DKP), a rapidly acting nonsteroidal anti-inflammatory drug, were co-loaded onto polymeric micelles and then incorporated into electrospun poly(vinyl alcohol)/poly(vinylpyrrolidone) (PVA/PVP) nanofiber intraocular implants. DSC, XRD, FTIR, and FESEM analyses showed that both APIs were successfully converted into nanofiber form without disrupting the micelle structure. Comparative studies with DKP solution and PSC commercial oral suspension (Noxafil[®] 40 mg/mL) showed that the produced micelle-loaded nanofibers provided sustained release and significantly increased ex vivo ocular permeation and penetration. In vitro antifungal activity tests demonstrated efficacy against Candida albicans, and HET-CAM toxicity tests showed that the micelle-loaded nanofibers were non-irritating and suitable for ocular application. Overall, the micelle-loaded electrospun nanofiber ocular inserts developed in this study represent a promising platform for combined antifungal and anti-inflammatory ocular therapy.

Onychomycoses are fungal infections of the nail unit, mainly caused by dermatophytes, and have a high prevalence worldwide. Current treatments for onychomycosis face challenges with the penetration of topically applied antifungal drugs through the nail barrier. Caryophyllene oxide is a sesquiterpenoid found in several essential oils that has antifungal properties. Clioquinol (CLI) is a broad-spectrum antifungal agent with potential for topical use. Combining a sesquiterpenoid compound with a synthetic antifungal drug offers a promising therapeutic and technological approach for treating onychomycoses, once both can be easily combined in a nanoemulsion formulation. This strategy requires the development of a quick and reliable method to evaluate their in vitro permeation and retention in the nail matrix, serving as a measure of formulation performance. In this study, using the Analytical Quality by Design (AQbD) approach, we developed and validated a rapid, sensitive bioanalytical method capable of simultaneously identifying and quantifying CLI and CAROX via high-performance liquid chromatography with a UV detector (HPLC-UV) at 215 nm, with retention times below 15 min. Additionally, an ungual permeation protocol was established, and the in vitro permeation and retention of CLI and CAROX in porcine hooves were assessed. Results showed that CLI retention within the nanoemulsion was four times higher than in solution (28.11 ± 4.85 vs 7.54 ± 3.03 μg/cm[2] after 72 h). For both CLI and CAROX, loading into nanostructured systems demonstrated a sustained release profile.

Terbinafine is an orally and topically active allylamine antifungal agent with fungistatic and fungicidal action. Its mechanism of action is the competitive inhibition of squalene epoxidase which leads to squalene accumulation and ergosterol depletion in the cell membrane. Clinically relevant pathogens can include but are not limited to: Aspergillus spp., Candida spp., Blastomyces dermatitidis, Histoplasma capsulatum, Emydomyces testavorans, Ophidiomyces ophiodiicola, and Batrachochytrium dendrobatidis. Terbinafine is an antifungal drug that has been used successfully in humans with few adverse effects. It is not licensed in the United States for systemic use in veterinary medicine but is routinely used in an extra label manner to treat fungal infections. Terbinafine has been well tolerated in domesticated and non-domesticated animals that have been studied. The studies that are available suggest that species differences exist in pharmacokinetics and further research is necessary to establish recommended doses in individual species. Due to the variation, terbinafine should be investigated on a species-by-species basis to determine its effective and safe use, thus ensuring the wellbeing of animals.

A chitinase-producing bacterium was isolated from a dumping ground soil sample and identified as Bacillus cereus V5331 based on 16S rRNA gene sequencing. The production of chitinase was enhanced through the application of solid-state fermentation (SSF). The effect of variables like pH, temperature, swollen chitin (SC) concentration, moisture content, inoculum size and incubation period were assessed by using a one-variable-at-a-time (OVAT) approach. A central composite design (CCD) using response surface methodology (RSM) was subsequently employed with the chitin concentration, moisture ratio, incubation period and inoculum size as found most effective independent variables. Optimization resulted in a 1.84 fold increase in chitinase production by meeting the parameters: 0.2% chitin, 1:1 moisture ratio, 1% inoculum and 120 h of incubation at 37 °C and pH 7 ± 0.2. The scanning electron microscopy (SEM) studies revealed that chitinase showed significant antifungal action against Candida albicans, causing cell wall disintegration, cell wall inhibition (1.5 cm) and substantial biofilm degradation (53.56%). Chitin breakdown was further confirmed by Fourier transform infrared spectroscopic (FTIR) analysis and p-DMAB assay of the enzyme-treated yeast, which showed the release of 211 µg mL-1 of N-acetylglucosamine (NAG). The current study demonstrates a newly isolated bacterium, which is non-hemolytic (gamma- hemolytic) and producing chitinase constitutively as well as in the presence of chitin in cost-effective locally available media. Further, its anti-fungal potential against C. albicans makes it a promising candidate for future studies to develop an antifungal topical therapeutic agent.

Background. Staphylococcus pseudintermedius (SP) and Malassezia pachydermatis (MP) are common causes of canine skin infections associated with increasing antimicrobial resistance. Topical products containing chlorhexidine and azoles have been utilized to treat these infections. However, a limited number of studies have assessed the interactions between chlorhexidine and azoles against SP and MP.Hypothesis/Objectives. To assess efficacy and potential additivity/synergy between chlorhexidine and azoles against clinical isolates of MP and multidrug-resistant SP (MDR-SP).Materials and Methods. A total of 30 MDR-SP and 30 MP isolates were tested using a modified broth microdilution method. Six twofold dilutions of 2% chlorhexidine gluconate, 1% miconazole nitrate and 0.15% ketoconazole were tested alone and in combination. Minimum inhibitory (MIC) and bactericidal/fungicidal (MBC/MFC) concentrations were recorded, and synergy, additivity or antagonism was calculated.Result. For MDR-SP, the combinations of chlorhexidine/miconazole (P=0.003) and chlorhexidine/ketoconazole (P<0.0001) resulted in lower MICs than chlorhexidine alone. Only the chlorhexidine/ketoconazole combination had lower MBCs (P=0.0071) than chlorhexidine alone. For MP, only the chlorhexidine/ketoconazole combination had lower MICs (P<0.0001) than chlorhexidine alone. Both combinations of chlorhexidine/miconazole (P=0.0028) and chlorhexidine/ketoconazole (P<0.0001) resulted in lower MFCs than chlorhexidine alone. Chlorhexidine/miconazole combination showed synergy in three MDR-SP isolates, but in none of the MP isolates. Chlorhexidine/ketoconazole showed synergy for 1 out of 30 MDR-SP and 19 out of 30 MP isolates.Conclusions and Clinical Relevance. These results suggest that chlorhexidine/azole combinations are an effective topical treatment for MDR-SP and MP infections. Further studies should assess the efficacy of commercial products containing these compounds and their efficacy in vivo.

Onychomycosis, a chronic fungal infection of the human nail, affects about 10 % of the global population. Treatment failure occurs in roughly 50 % of patients due to difficulties in concentrating antifungal agents within the nail tissue. To address this issue, we have developed a hydrosulphide ion gel to deliver hydrogen sulphide (H2S) gas into the human nail plate. Using sodium hydrogen sulphide (NaHS), which produces H2S more effectively than three alternative chemical donors, maintaining a pH of 8.5 to optimise the hydrosulphide micro-species, and enclosing the gel in a microchamber, allows delivery of 1 mg/cm[2] of H2S through the nail in just 4 h. This level of delivery exceeds what is typically achieved after 4 weeks of repeated commercial topical antifungal applications. The hydrosulphide ion gel generates H2S in the liquid state, which then converts into gas within the nail. Both the liquid and gaseous forms of H2S contribute to the gel's antifungal effects. The liquid H2S exhibits kill assay IC50 values of 2.8 µg/mL for Trichophyton rubrum and 3.7 µg/mL for Candida albicans. The H2S gas shows minimum inhibitory concentrations (MICs) of 0.02 µg/mL for T. rubrum and 0.1 µg/mL for C. albicans. In vivo pharmacokinetic assessments in rodents demonstrate that the hydrosulphide ion gel enables targeted penetration into nail tissue without systemic exposure. Finally, in a fungal-infected human nail, a single 24-hour treatment achieves complete eradication, suggesting that topical application of a hydrosulphide ion gel could significantly reduce the current 6-month treatment cycle for chronic fungal nail infections. STATEMENT OF SIGNIFICANCE: Onychomycosis is a fungal infection of the human nail that can last for decades, causing recurring skin infections, tissue distortion, and difficulty walking and exercising. Current treatments are ineffective because, whether an antifungal agent is applied directly to the nail plate or taken as a tablet, it must penetrate the hard keratin of the nail where the fungus resides. We have designed a hydrosulphide ion gel to deliver hydrogen sulphide (H2S) gas into the human nail plate. H2S is very small, so it rapidly penetrates the nail, reaching levels within 4 h that are higher than those achieved by daily application of commercial antifungals for 4 weeks, without causing nail tissue damage or blood absorption. This alternative topical treatment could be life-changing for patients with chronic onychomycosis.