Mesoporous zinc oxide-based drug delivery system offers an antifungal and immunoregulatory strategy for treating keratitis.

Fungal keratitis is a refractory eye disease that is prone to causing blindness. Fungal virulence and inflammatory responses are two major factors that accelerate the course of fungal keratitis. However, the current antifungal drugs used for treatment usually possess transient residence time on the ocular surface and low bioavailability deficiencies, which limit their therapeutic efficacy. In this work, natamycin (NATA)-loaded mesoporous zinc oxide (Meso-ZnO) was synthesized for treating Aspergillus fumigatus keratitis with excellent drug-loading and sustained drug release capacities. In addition to being a carrier for drug delivery, Meso-ZnO could restrict fungal growth in a concentration-dependent manner, and the transcriptome analysis of fungal hyphae indicated that it inhibited the mycotoxin biosynthesis, oxidoreductase activity and fungal cell wall formation. Meso-ZnO also promoted cell migration and exhibited anti-inflammatory role during fungal infection by promoting the activation of autophagy. In mouse models of fungal keratitis, Meso-ZnO/NATA greatly reduced corneal fungal survival, alleviated tissue inflammatory damage, and reduced neutrophils accumulation and cytokines expression. This study suggests that Meso-ZnO/NATA can be a novel and effective treatment strategy for fungal keratitis.

Fabrication of antimicrobial PCL/EC nanofibrous films containing natamycin and trans-cinnamic acid by microfluidic blow spinning for fruit preservation.

Fruit is susceptible to various postharvest pathogens; thus, the development of multifunctional preservation materials that can achieve the broad-spectrum inhibition of different pathogens is a current research hotspot. Here, microfluidic blow spinning was used to create a biodegradable polycaprolactone/ethyl cellulose (PCL/EC) nanofibrous film that incorporated two naturally-sourced compounds, natamycin and trans-cinnamic acid, resulting in multi-microbial inhibition. The PCL/EC-based film had a smooth and even morphology, indicating the favorable integration of PCL and EC. After the incorporation of ingredients, the film exhibited good inhibitory activity against Escherichia coli, Staphylococcus aureus, and Botrytis cinerea, and it had finer fiber diameters, higher permeability, and antioxidant properties. We further demonstrated that strawberries that were padded with the film had good resistance to Botrytis cinerea. Also, the film did not interference with the qualities of the strawberries during storage. The study demonstrates a promising application for multi-antimicrobial and bio-friendly packaging materials in postharvest fruit preservation.

Antifungal susceptibility profiles for fungal isolates from corneas and contact lenses in the United Kingdom.

OBJECTIVE: To report the identification and results of susceptibility testing for fungal isolates from the cornea or contact lens care systems. MATERIALS AND METHODS: In this retrospective epidemiological study, we searched the results of fungal cultures from cornea or contact lens systems referred for identification and susceptibility testing to the United Kingdom National Mycology Reference Laboratory between October 2016 and March 2022. For each fungal isolate, we recorded the genus and species of the fungus and the minimum inhibitory concentration (MIC) to six antifungal agents available to treat corneal infection (amphotericin, econazole, itraconazole, natamycin, posaconazole, and voriconazole). RESULTS: There were 600 isolates from 585 patients, comprising 374 (62%) from corneal samples and 226 from contact lenses and care systems, of which 414 (69%) isolates were moulds (filamentous fungi) and 186 (31%) were yeasts. The most frequent moulds isolated were Fusarium spp (234 isolates, 39%) and Aspergillus spp (62, 10%). The most frequent yeasts isolated were Candida spp (112, 19%), predominantly Candida parapsilosis (65, 11%) and Candida albicans (33, 6%), with 35 isolates (6%) of Meyerozyma guilliermondii. In vitro susceptibility was greatest for natamycin (347 moulds tested, mode 4 mg/L, range 0.25-64 mg/L; 98 yeasts tested, mode 4 mg/L, range 0.5-32 mg/L), with susceptibility for 94% for moulds and 99% yeasts. Of the 16 isolates interpreted as highly resistant to natamycin (MIC ≥16 mg/L), 13 were Aspergillus flavus complex. CONCLUSIONS: In vitro susceptibility supports the use of natamycin for the empiric treatment of fungal keratitis in the UK.

Improved Topical Ophthalmic Natamycin Suspension for the Treatment of Fungal Keratitis.

Purpose: Natamycin (NT) is used as a first-line antifungal prescription in the treatment of fungal keratitis (FK) and is commercially available as a 5% w/v ophthalmic suspension. NT shows poor water solubility and light sensitivity. Thus, the present investigation is aimed to enhance the fraction of NT in solution in the commercial formulation by adding cyclodextrins (CDs), thereby improving the delivery of the drug into deeper ocular tissues. Methods: The solubility of NT in different CDs, the impact of ultraviolet (UV) light exposure, stability at 4°C and 25°C, in vitro release, and ex vivo transcorneal permeation studies were performed. Results: NT exhibited the highest solubility (66-fold) in randomly methylated-ß-cyclodextrin (RM-ßCD) with hydroxypropyl-ßCD (HP-ßCD) showing the next highest solubility (54-fold) increase in comparison to market formulation Natacyn® as control. The stability of NT-CD solutions was monitored for 2 months (last-time point) at both storage conditions. The degradation profile of NT in NT-RM-ßCD and NT-HP-ßCD solutions under UV-light exposure followed first-order kinetics exhibiting half-lives of 1.2 h and 1.4 h, respectively, an almost 3-fold increase over the control solutions. In vitro release/diffusion studies revealed that suspensions containing RM-ßCD and HP-ßCD increased transmembrane flux significantly (3.1-fold) compared to the control group. The transcorneal permeability of NT from NT-RM-ßCD suspension exhibited an 8.5-fold (P < 0.05) improvement compared to Natacyn eyedrops. Furthermore, the addition of RM-ßCD to NT suspension increases the solubilized fraction of NT and enhances transcorneal permeability. Conclusion: Therefore, NT-RM-ßCD formulations could potentially lead to a decreased frequency of administration and significantly improved therapeutic outcomes in FK treatment.

Study on the Antifungal Activity and Potential Mechanism of Natamycin against Colletotrichum fructicola.

In this investigation, the antifungal activity, its influence on the quality of apples, and the molecular mechanism of natamycin against Colletotrichum fructicola were systematically explored. Our findings indicated that natamycin showed significant inhibition against C. fructicola. Moreover, it efficaciously maintained the apple quality by modulating the physicochemical index. Research on the antifungal mechanism showed that natamycin altered the mycelial microstructure, disrupted the plasma membrane integrality, and decreased the ergosterol content of C. fructicola. Interestingly, the exogenous addition of ergosterol weakened the antifungal activity of natamycin. Importantly, natamycin markedly inhibited the expression of Cyp51A and Cyp51B genes in C. fructicola, which was contrary to the results obtained after treatment with triazole fungicide flusilazole. All these results exhibited sufficient proof that natamycin had enormous potential to be conducive as a promising biopreservative against C. fructicola on apples, and these findings will advance our knowledge on the mechanism of natamycin against pathogenic fungi.

Development, characterization and functional properties of sodium alginate-based films incorporated with Schisandra chinensis extract-natamycin complex.

Because of the impact of petroleum-based polymers on environmental deterioration and the need for safe, efficient, and functional packaging films, a sodium alginate (SA)-based film incorporating a Schisandra chinensis extract (SCE)-natamycin (NA) complex was developed for the desired physical and functional properties. The incorporation of SCE-NA into SA-based films decreased the water vapor transmission rate (WVTR), moisture content (MC), and hydrophilicity of the films and improved their opacity, elongation at break (EAB), and thermal stability. Scanning Electron Microscopy (SEM), Fourier Transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray Diffraction (XRD) analyses showed that SA, SCE, and NA had positive interactions and compatibility. In addition, the antimicrobial activity analysis indicated that the SA-SCE-NA film-forming solutions had satisfactory antimicrobial activity against Staphylococcus aureus, Escherichia coli, Saccharomyces cerevisiae, and Aspergillus niger. SA-based composite films have been used to coat cucumbers and blueberries to extend their shelf life. Compared to the neat SA film, the shelf life of cucumbers treated with the SA-SCE-NA film increased by 6 days compared to that in the untreated group at 28 °C, and the shelf life of blueberries increased by 5 days at 4 °C, revealing its potential utilization in food packaging.

Clinical and in vivo confocal microscopy characteristics of Candida keratitis following keratoplasty.

BACKGROUND: We present six patients who developed Candida keratitis postoperatively. The clinical features, diagnostic testing including in vivo confocal microscopy, and outcomes are presented. METHODS: Six patients who developed Candida keratitis following penetrating and endothelial keratoplasty, were referred to Tianjin Medical University Eye Hospital between 2018 to 2021.The diagnosis was established following cultures of either corneal scraping or biopsy. In vivo confocal microscopy examination was also performed to confirm the diagnosis and characterize the morphology, distribution and the depth of Candida spp. All patients were treated with topical voriconazole (VCZ) 1% and natamycin (NTM) 5%. Patients with mid/deep stromal keratitis or interface infection were treated additionally with intrastromal or interface VCZ irrigation (0.05 mg/0.1mL). RESULTS: The cultures of corneal scrapings (4 cases) or biopsies (2 cases) were all positive for Candida spp. In vivo confocal microscopy examination was positive for fungal elements in five of the six patients. The infection resolved in five of the six patients. The patients' final uncorrected visual acuity (UCVA) ranged from hand movements (HM) to 20/80. CONCLUSION: In vivo confocal microscopy is a useful non-invasive clinical technique for confirming the diagnosis of Candida keratitis. Intrastromal and interface irrigated VCZ injections are effective treatment options.

The preparation and therapeutic effects of ß-glucan-specific nanobodies and nanobody-natamycin conjugates in fungal keratitis.

Fungal keratitis (FK) is a severe infectious corneal disease. Since traditional eye drops exhibit poor dissolution and high corneal toxicity, the efficacy of current treatments for FK remains limited. It is needed to develop new approaches to control the cornea damage from FK. In this study, a nanobody (Nb) specific to ß-glucan in the fungal cell wall was prepared. The conjugate of the Nb with natamycin (NAT), a traditional antifungal drug, was synthesized. Firstly, we found the Nb specific to ß-glucan inhibited fungal growth by disrupting cell wall and biofilm formation.. In addition, the content of ß-glucan in the fungal cell wall decreased after Nb treatment. The Nb also reduced the adhesion ability of fungal conidia to human corneal epithelial cells (HCECs). Further, we examined the difference between NAT and Nb-NAT in antifungal growth. Nb-NAT showed better antifungal effects than NAT which was caused by the interaction between Nb and ß-glucan. Moreover, Nb concentration below 0.5 mg/mL did not affect the viability of HCECs. Nb-NAT had less cytotoxicity and ocular surface irritation than NAT. Nb specific to ß-glucan attenuated Aspergillus fumigatus (A. fumigatus) virulence and relieved inflammatory responses in FK. Nb-NAT treatment of the cornea improved therapeutic effects compared with NAT. It decreased clinical scores and expression level of inflammatory factors. To our knowledge, this study is the first to report a Nb specific to ß-glucan and Nb-NAT for the treatment of FK. These unique functions of the Nb specific to ß-glucan and Nb-NAT would render it as an alternative molecule to control fungal infections including FK. STATEMENT OF SIGNIFICANCE: Fungal keratitis is a corneal disease with a high rate of blindness. Due to the poor dissolution and high corneal toxicity exhibited by traditional eye drops, the efficacy of current therapeutic treatments for fungal keratitis (FK) remains limited. To enhance the therapeutic effect of natamycin in treating fungal keratitis, this study developed an innovative approach by preparing a ß-glucan-specific nanobody and loading it with the antifungal drug natamycin. The ß-glucan-specific nanobody has the ability to control both fungal pathogen invasion and inflammation, which can cause damage to the cornea in FK. The conjugation with the ß-glucan-specific nanobody significantly increased the antifungal capacity of natamycin and reduced its toxicity. The further application of natamycin conjugated with the ß-glucan-specific nanobody could be expanded to other diseases caused by fungal pathogen infections.

Rapid microwave synthesis of N and S dual-doped carbon quantum dots for natamycin determination based on fluorescence switch-off assay.

Green, one-pot, quick, and easily synthesized nitrogen and sulfur co-doped carbon quantum dots (N,S-CDs) were obtained from cheap and readily available chemicals (sucrose, urea, and thiourea) using a microwave-assisted approach in about 4 min and utilized as a turn-off fluorescent sensor for estimation of natamycin (NAT). First, the effect of N and S doping on the microwave-synthesized CDs' quantum yield was carefully studied. CDs derived from sucrose alone failed to produce a high quantum yield; then, to increase the quantum yield, doping with heteroatoms was carried out using either urea or thiourea. A slight increase in quantum yield was observed upon using thiourea with sucrose, while an obvious enhancement of quantum yield was obtained when urea was used instead of thiourea. Surprisingly, using a combination of urea and thiourea together results in N,S-CDs with the highest quantum yield (53.5%), uniform and small particle size distribution, and extended stability. The fluorescent signal of N,S-CDs was quenched upon addition of NAT due to inner filter effect and static quenching in a manner that allowed for quantitative determination of NAT over a range of 0.5-10.0µg ml-1(LOD = 0.10µg ml-1). The N,S-CDs were applicable for determination of NAT in aqueous humor, eye drops, different environmental water samples, and bread with excellent performance. The selectivity study indicated excellent selectivity of the prepared N,S-CDs toward NAT with little interference from possibly interfering substances. In-silico toxicological evaluation of NAT was conducted to estimate its long-term toxicity and drug-drug interactions. Finally, the preparation of N,S-CDs, and analytical procedure compliance with the green chemistry principles were confirmed by two greenness assessment tools.

Fabrication of carboxymethyl chitosan films for cheese packaging containing gliadin-carboxymethyl chitosan nanoparticles co-encapsulating natamycin and theaflavins.

In this study, gliadin-carboxymethyl chitosan composite nanoparticles (GC NPs) co-encapsulated natamycin (Nata) and theaflavins (TFs) were constructed and added as an antioxidant, antifungal, and structural enhancer to carboxymethyl chitosan (CMCS) films. The stabilized GC NPs with a particle size of 160.7 ± 2.8 nm, a zeta potential of -29.0 ± 0.9 mV, and a protein content in the supernatant of 96 ± 1 % could be fabricated. Tests of pH and salt ions showed that the stability of NPs dispersion was based on electrostatic repulsion. Co-encapsulation of TFs enhanced the photostability of Nata and the antioxidant activity of the NPs dispersion. The interactions between gliadin with Nata and TFs were studied by molecular simulations. As a functional additive, the addition of Nata/TFs-GC NPs could improve the optical properties, mechanical properties, water-blocking capability, and antifungal and antioxidant activities of the CMCS films. The in-vivo test showed that the functional film could be used to inhibit the growth of Aspergillus niger on cheese.

Sensitivity of Mucor piriformis to Natamycin and Efficacy of Natamycin Alone and with Salt and Heat Treatments Against Mucor Rot of Stored Mandarin Fruit.

Mucor rot caused by Mucor piriformis is an emerging postharvest disease of mandarin fruit in California. Natamycin is a newly registered biofungicide for postharvest use on citrus and some other fruits. In the study, baseline sensitivity to natamycin in 50 isolates of M. piriformis was determined in vitro. The mean EC50 (effective concentration to inhibit sporangiospore germination by 50%) and MIC (minimum inhibitory concentration to inhibit mycelial growth by 100%) values were 0.59 µg/ml and less than 1.0 µg/ml, respectively. Natamycin at the label rate of 920 µg/ml alone or in combination with 3% potassium sorbate (PS) or 3% sodium carbonate (SC) applied at 20 or 50°C was evaluated for control of Mucor rot on inoculated 'Tango' mandarin fruit. Natamycin alone reduced Mucor rot incidence on stored mandarin fruit from 100% among nontreated control fruit to approximately 30%, a reduction of more than 70% compared to the nontreated control, while 3% PS and 3% SC had no to little control. When applied at 50°C, natamycin and 3% PS reduced Mucor rot incidence by 65.0 and 31.2%, respectively; while natamycin in combination with 3% PS reduced disease incidence by 92.5% compared to the nontreated control after 2 weeks of storage at 5°C. This combined treatment remained effective even when the application of the treatment was delayed for 6 and 12 h after inoculation. However, the effectiveness of the treatments declined when storage was extended to 3 or 4 weeks. Natamycin can be an effective tool to control Mucor rot on mandarin fruit, and minimizing the period of extended storage could help maintain the control efficacy of natamycin.

Natamycin Ocular Delivery: Challenges and Advancements in Ocular Therapeutics.

Fungal keratitis, an ocular fungal infection, is one of the leading causes of monocular blindness. Natamycin has long been considered the mainstay drug used for treating fungal keratitis and is the only US Food and Drug Administration (USFDA)-approved drug, commercially available as a topical 5% w/v suspension. Furthermore, ocular fungal infection treatment takes a few weeks to months to recover, and the available marketed antifungal suspensions are associated with poor residence time, limited bioavailability (< 5%) and high dosing frequency as well as minor irritation and discomfort. Despite these challenges, natamycin is still the preferred drug choice for treating fungal keratitis, as it has fewer side effects and less ocular toxicity and is more effective against Fusarium species than other antifungal agents. Several novel therapeutic approaches for the topical delivery of natamycin have been reported to overcome the challenges posed by the conventional dosage forms and to improve ocular bioavailability for the efficient management of fungal keratitis. Current progress in the delivery systems uses approaches aimed at improving the corneal residence time, bioavailability and antifungal potency, thereby reducing the dose and dosing frequency of natamycin. In this review, we discuss the various strategies explored to overcome the challenges present in ocular drug delivery of natamycin and improve its bioavailability for ocular therapeutics.

Natamycin Has an Inhibitory Effect on Neofusicoccum parvum, the Pathogen of Chestnuts.

This research aimed to investigate natamycin's antifungal effect and its mechanism against the chestnut pathogen Neofusicoccum parvum. Natamycin's inhibitory effects on N. parvum were investigated using a drug-containing plate culture method and an in vivo assay in chestnuts and shell buckets. The antifungal mechanism of action of natamycin on N. parvum was investigated by conducting staining experiments of the fungal cell wall and cell membrane. Natamycin had a minimum inhibitory concentration (MIC) of 100 µg/mL and a minimum fungicidal concentration (MFC) of 200 µg/mL against N. parvum. At five times the MFC, natamycin had a strong antifungal effect on chestnuts in vivo, and it effectively reduced morbidity and extended the storage period. The cell membrane was the primary target of natamycin action against N. parvum. Natamycin inhibits ergosterol synthesis, disrupts cell membranes, and causes intracellular protein, nucleic acid, and other macromolecule leakages. Furthermore, natamycin can cause oxidative damage to the fungus, as evidenced by decreased superoxide dismutase and catalase enzyme activity. Natamycin exerts a strong antifungal effect on the pathogenic fungus N. parvum from chestnuts, mainly through the disruption of fungal cell membranes.

Fungal Keratitis Caused by Talaromyces coalescens: A Case Report.

Fungal keratitis is a severe corneal infection, and the causative fungi include various rare fungal species. Fungal keratitis caused by Talaromyces species has yet to be reported, and there is no information about this fungus as a cause of keratitis. A 77-year-old man developed fungal keratitis while waiting for a donor cornea due to bullous keratopathy in his left eye. Fungal culture of a corneal scraping grew filamentous fungi, which were morphologically identified as Paecilomyces species. The corneal infection did not improve after topical administration of 1% voriconazole, and ribosomal DNA sequencing definitively verified the fungus to be Talaromyces coalescens. The lesion gradually improved after switching to topical 5% natamycin. Antifungal susceptibility tests determined the high minimum inhibitory concentrations of voriconazole to be > 8 µg/mL. This is the first report of Talaromyces fungal keratitis. Clinicians, especially those in ophthalmology, need to be aware of this rare fungus.

The therapeutic role and mechanism of 4-Methoxycinnamic acid in fungal keratitis.

Fungal keratitis is an infectious vision-threatening disease that has a poor prognosis, and the clinical therapeutic drugs have multiple limitations, such as epithelial toxicity and low bioavailability. Therefore, new antifungal treatment strategies must be developed. 4-Methoxycinnamic acid (MCA) is a widely occurring natural phenolic acid that has been proven to have multiple effects, such as antibacterial, antifungal, anti-inflammatory, neuroprotective, and inhibiting cancer. In this research, we explored the effects and underlying mechanisms of MCA on A. fumigatus keratitis and the antifungal effects of the combination of MCA and natamycin (NATA) on A. fumigatus. We found that MCA exerts antifungal effects by inhibiting the synthesis of the fungal cell wall, changing the permeability of fungal cell membranes. Moreover, the MCA-NATA combination exhibited synergy for A. fumigatus. In addition, MCA exerted an anti-inflammatory effect by downregulating the inflammatory factors (IL-1ß, TNF-α, IL-6, and iNOS) in C57BL/6 mice and RAW264.7 cells. The anti-inflammatory mechanism of MCA was associated with the Mincle signal pathway. In summary, MCA acts as a potential therapeutic drug for fungal keratitis and a potential antifungal sensitizer for natamycin. MCA inhibits fungal cell wall synthesis, destroys the permeability of fungal cell membranes, and mediates the anti-inflammatory, immune response of the host.

Antifungal and antiaflatoxigenic mechanism activity of freeze-dried culture filtrate of Streptomyces philanthi RL-1-178 on the two aflatoxigenic fungi and identification of its active component.

AIMS: The study reports the antifungal and antiaflatoxigenic mechanism activity of freeze-dried culture filtrate of Streptomyces philanthi RL-1-178 (DCF RL-1-178) against two aflatoxigenic strains (Aspergillus parasiticus and A. flavus) and identification of its active component. METHODS AND RESULTS: Significant inhibition in ergosterol biosynthesis by the DCF RL-1-178 appeared on the plasma membrane. Moreover, the DCF RL-1-178 showed dose-dependent inhibition of methylglyoxal (MG) (an aflatoxin inducer) biosynthesis and exhibited a novel antiaflatoxigenic action mechanism. Significant impairments in enzymatic [superoxide dismutase (SOD) and catalase (CAT)] and nonenzymatic [oxidized and reduced glutathione (GSH) and ratio of oxidized and reduced glutathione (GSSG)] anti-oxidative defense molecules were observed in the two aflatoxigenic cells. The active component of the DCF RL-1-178 was identified as natamycin. The natamycin exhibited against A. parasiticus and A. flavus with the minimum inhibitory concentration (MIC) values of 0.5 and 1.0 µg ml-1, respectively, while the minimum fungicidal concentration values were the same (4.0 µg ml-1). CONCLUSIONS: The DCF RL-1-178 containing natamycin exhibited the following effects: (1) inhibition of cellular ergosterol biosynthesis on plasma membrane, (2) reduction in MG (aflatoxin inducer) confirmed novel antiaflatoxigenic mechanism of action, and (3) caused remarkable debasement in antioxidant defense enzymes (SOD and CAT) and nonenzymatic defense molecules (GSH and GSSG) revealing biochemical mechanism of action.

Theoretical Studies of Mutual Effects between 6-m-r Hemiketalization and 26-m-r Lactonization in Pimaricin Thioesterase.

Pimaricin is a small polyene macrolide antibiotic and has been broadly used as an antimycotic and antiprotozoal agent in both humans and foods. As a thioesterase in type-I polyketide synthase, pimTE controls the 26-m-r macrolide main chain release in pimaricin biosynthesis. In this work, we sought to determine whether the 6-m-r hemiketal formation was linked to pimTE-catalyzed 26-m-r lactonization. Compared to non-hemiketal TEs, pimTE is characterized by an aspartic acid residue (D179) accessible to the U-turn motif in the acyl-enzyme intermediate. Both the covalent docking and molecular dynamics simulations demonstrate that the reactive conformations for macrocyclic lactonization are drastically promoted by the 6-m-r hemiketal. Moreover, the small-model quantum mechanistic calculations suggest that protic residues can significantly accelerate the 6-m-r hemiketal cyclization. In addition, the post-hemiketal molecular dynamic simulations demonstrate that hydrogen-bonding networks surrounding the substrate U-turn of the hairpin-shaped conformation changes significantly when the 6-m-r hemiketal is formed. In particular, the R-hemiketal intermediate is not only catalyzed by the D179 residue, but also twists the hairpin structure to the 26-m-r lactonizing pre-reaction state. By contrast, the S-hemiketal formation is unlikely catalyzed by D179, which twists the hairpin in an opposite direction. Our results propose that pimTE could be a bi-functional enzyme, which can synergistically catalyze tandem 6-m-r and 26-m-r formations during the main-chain release of pimaricin biosynthesis.

Pentoxifylline treats Aspergillus fumigatus keratitis by reducing fungal burden and suppressing corneal inflammation.

Fungal keratitis (FK) is a blinding ocular disease, which mainly results from fungal damage and excessive inflammation. Pentoxifylline, a kind of methylxanthine, has been discovered to have anti-inflammatory properties in various infectious diseases, hinting a potential therapeutic effect on treating corneal fungal infection. Whereas, the therapeutic impact of pentoxifylline on fungal keratitis is still uncertain. This study investigated the antifungal capability against Aspergillus fumigatus and the anti-inflammatory role of pentoxifylline by activating nuclear factor, erythroid 2 like 2 (Nrf2)/heme oxygenase1 (HO1) pathway in the process of FK. In our research, we demonstrated that pentoxifylline could effectively inhibit fungal growth and inflammatory reaction. Pentoxifylline reduced the production of pro-inflammatory factors by stimulating the Nrf2/HO1 pathway. Although there was no statistical difference between the curative efficacy of pentoxifylline and natamycin application to FK, pentoxifylline could promote corneal epithelial repair and was less toxicity to the ocular surface than natamycin. In conclusion, pentoxifylline performs antifungal and anti-inflammatory effects by lessening the fungus burden and activating the Nrf2/HO1 pathway, hinting that it has the potential to be a new therapeutic medication for Aspergillus fumigatus keratitis.

Case Report: A Rare Fungal Keratitis Caused by Plectosphaerella Cucumerina.

PURPOSE: To report a rare case of fungal keratitis caused by Plectosphaerella cucumerina. METHODS: This study retrospectively reviewed the medical records of a case of fungal keratitis. RESULTS: Silt-lamp biomicroscopy revealed corneal infiltration and epithelial defects. Anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM) were performed to assist in the diagnosis and evaluate corneal conditions. The isolate was identified as Plectosphaerella cucumerina by MALDI-TOF mass spectrometry. The patient was treated with topical 5% pimaricin and oral voriconazole for 1 month and recovered. CONCLUSION: Fungal keratitis caused by Plectosphaerella cucumerina is rare. AS-OCT and IVCM can help locate the lesion and diagnose fungal keratitis. Furthermore, MALDI-TOF mass spectrometry showed potential prospects in the identification of filamentous fungi. Plectosphaerella cucumerina rarely infects humans and is sensitive to antifungal agents such as pimaricin and voriconazole.

Application of natamycin and farnesol as bioprotection agents to inhibit biofilm formation of yeasts and foodborne bacterial pathogens in apple juice processing lines.

Biofilms serve as a reservoir for pathogenic and spoilage microorganisms, and their removal from different surfaces is a recurring problem in the beverage industry. This study aimed to investigate the effect of a combination of natamycin (NAT, 0.01 mmol/l) and farnesol (FAR, 0.6 mmol/l) against biofilms on ultrafiltration (UF) membranes and stainless steel (SS) surfaces using apple juice as food matrix. The co-adhesion of Rhodotorula mucilaginosa, Candida tropicalis, C. krusei and C. kefyr (mixed-yeast) with Listeria monocytogenes, Salmonella enterica or Escherichia coli O157:H7 (multi-species) in presence of NAT + FAR was evaluated for 2, 24, 48 h. In biofilms treated with NAT + FAR were observed by cell quantification and microscopy, inhibition of the filamentous yeast forms, disruption of the tri-dimensional structure and a high detachment of yeast cells. NAT + FAR affected the biofilms independently of the surfaces used and the presence (or not) of bacteria. L. monocytogenes was the most susceptible (p < 0.001) in multi-species biofilms, followed by E. coli O157:H7 on both surfaces (p < 0.001), whereas the growth of S. enterica was reduced (p < 0.05) in SS but not in UF-membranes (p > 0.05). Since the combination NAT + FAR affected the structure and viability of yeast species and foodborne pathogens in multi-species biofilms developed on UF-membranes and SS surfaces, the combination proposed could be considered a promising control agent to prevent biofilms in apple juice processing lines.