Antimicrobial susceptibility of Fusarium, Aspergillus, and other filamentous fungi isolated from keratitis

A novel procedure for the quantification of antifungal activity against filamentous fungi, mycelial invasion distance (MID) method

A novel method for the quantification of antifungal activity of fungicides and painted surfaces, mycelial invasion distance (MID) method, was developed and applied to the quantification of activities of parabens and an antifungal paint. In this method, the MID of aerial mycelia on a test paper or a panel placed on a nutrient agar plate was measured with a stereoscopic microscope and a micro-ruler. The antifungal activities of the parabens and painted surfaces were expressed as the MID. The higher the hydrophobicity of parabens, the longer the MID, that is the lower the antifungal activity, were observed. Conversely, relatively polar parabens, such as methyl and ethyl parabens, exhibited stronger antifungal activity, that is shorter MID. The most hydrophobic paraben, benzyl paraben, showed the weakest antifungal activity. Furthermore, it was confirmed that the MID method was effective for the evaluation of the painted surfaces.

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.

Fusarium Keratitis From a Comprehensive Eye Health Care Facility in South India: Molecular Characterization by MALDI-TOF Versus PCR Sequencing, Species Complex Distribution, and Clinical Correlation

PURPOSE

Fusarium keratitis possesses significant diagnostic and therapeutic challenges. Medically relevant Fusaria belong to various species complexes and show prominent differences in their antifungal susceptibility profile which may influence the clinical outcome. Rapid diagnostic methods are warranted for precise identification of species complexes for prompt initiation of correct antifungals. The aim of the study was to compare between matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and PCR sequencing for correct species-level identification and to analyze the clinical outcome among different Fusarium species complexes.

METHODS

Twenty-nine culture-proven Fusarium keratitis cases were included in this study. A phylogenetic tree was constructed after TEF1α gene sequencing and isolates were subjected to MALDI-TOF MS, followed by database expansion and identification. Clinical outcome and risk association among species complexes were analyzed retrospectively.

RESULTS

Maximum likelihood phylogeny categorized 68.9% isolates as Fusarium solani species complex (FSSC), 17.2% as Fusarium dimerum species complex (FDSC), followed by 13.7% as Fusarium fujikuroi species complex (FFSC). With extended database, MALDI-TOF MS could correctly speciate 96.5% (28/29) isolates. Previous antibiotic usage (P = 0.034) and preoperative antifungal treatment with natamycin, voriconazole, or ketoconazole (P = 0.025) were significantly higher in the FSSC group. The patients in the FFSC group had a significantly longer duration of symptoms at the time of clinical presentation to the clinic (15 days vs. 5 days, P = 0.030). Among 11 patients with a clinically poor outcome, 9 (31%) had FSSC infection.

CONCLUSIONS

Patients infected with the FSSC had more aggressive infection with poor prognosis. MALDI-TOF MS can serve as the best alternative method to conventional molecular identification with reduced turnaround time, which may help the ophthalmologists to consider the appropriate antifungals or early surgical intervention for improved outcome.

Caspofungin-Loaded Formulations for Treating Ocular Infections Caused by Candida spp

Fungal keratitis causes corneal blindness worldwide. The treatment includes antibiotics, with Natamycin being the most commonly used; however, fungal keratitis is difficult to treat, so alternative therapies are needed. In situ gelling formulations are a promising alternative; this type of formulation has the advantages of eye drops combined with the advantages of ointments. This study was designed to develop and characterize three formulations containing 0.5% CSP: CSP-O1, CSP-O2, and CSP-O3. CSP is an antifungal drug that acts against a diverse variety of fungi, and Poloxamer 407 (P407) is a polymer of synthetic origin that is able to produce biocompatible, biodegradable, highly permeable gels and is known to be thermoreversible. Short-term stability showed that formulations are best stored at 4 °C, and rheological analysis showed that the only formulation able to gel in situ was CSP-O3. In vitro release studies indicated that CSP-O1 releases CSP most rapidly, while in vitro permeation studies showed that CSP-O3 permeated the most. The ocular tolerance study showed that none of the formulations caused eye irritation. However, CSP-O1 decreased the cornea's transparency. Histological results indicate that the formulations are suitable for use, with the exception of CSP-O3, which induced slight structural changes in the scleral structure. All formulations were shown to have antifungal activity. In view of the results obtained, these formulations could be promising candidates for use in the treatment of fungal keratitis.

Fungal keratitis in Iran: Risk factors, clinical features, and mycological profile

Introduction

This study was intended to investigate the clinical features and predisposing factors of fungal keratitis (FK), as well as molecular identification and antifungal susceptibility of causative agents in Tehran, Iran.

Methods

This cross-sectional study was carried out from April 2019 to May 2021. All fungi isolates were identified using conventional methods and were confirmed by DNA-PCR-based molecular assays. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) was used to identify yeast species. Minimum inhibitory concentrations (MIC) of eight antifungal agents were assessed according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) microbroth dilution reference method.

Results

Fungal etiology was confirmed in 86 (7.23%) of 1189 corneal ulcers. A significant predisposing factor for FK was ocular trauma caused by plant materials. Therapeutic penetrating keratoplasty (PKP) was required in 60.4% of cases. The predominant fungal species isolated was Fusarium spp. (39.5%) followed by Aspergillus spp. (32.5%) and Candida spp. (16.2%).

Discussion

The MIC results indicate that amphotericin B may be appropriate for treating FK caused by Fusarium species. FK caused by Candida spp. can be treated with flucytosine, voriconazole, posaconazole, miconazole, and caspofungin. In developing countries such as Iran, corneal infection due to filamentous fungi is a common cause of corneal damage. In this region, fungal keratitis is observed primarily within the context of agricultural activity and subsequent ocular trauma. Fungal keratitis can be managed better with understanding the "local" etiologies and antifungal susceptibility patterns.

Green chemistry principles for the synthesis of anti fungal active gum acacia-gold nanocomposite - natamycin (GA-AuNC-NT) against food spoilage fungal strain Aspergillus ochraceopealiformis and its marked Congo red dye adsorption efficacy

In this present study, a highly stable gum acacia -gold nanocomposite fabricated with food preservative agent natamycin (GA-AuNC-NT) was prepared via green science principles under in vitro conditions. Various characterisation techniques reveal highly stable structural, functional properties of the synthesised nanocomposite with marked antifungal activity and adsorption efficacy against congo red dye. The antifungal activity was investigated against the fungal strain Aspergillus ochraceopealiformis isolated from spoiled, expired bread. The well diffusion assay, fungal hyphae fragmentation assay and spore germination inhibition assay were used to determine the antifungal activity of the synthesised nanocomposite. Potential antifungal activity of the synthesised nanocomposite was confirmed by recording zone of inhibition, high rate of hyphae fragmentation and marked spore germination inhibition against the tested fungal strain. The molecular mechanism of antifungal activity was studied by measuring oxidative stress marker genes like catalase (CAT), superoxide dismutase (SOD), peroxidase (POD) induction adopting quantitative real-time polymerase chain reaction (q RT-PCR). Among the various treatment, a notable reduction in all the tested marker genes expression was recorded in the nanocomposite treated fungal strain. Release profile studies using different solvents reveals sustained or controlled release of natamycin at the increasing periods. The synthesised nanocomposite's high safety or biocompatibility was evaluated with the Wistar animal model by determining notable changes in behavioural, biochemical, haematological and histopathological parameters. The synthesised nanocomposite did not exhibit any undesirable changes in all the tested parameters confirming the marked biosafety or biocompatibility. The nanocomposite was coated on the bread packaging material. The effect of packaging on the proximate composition, antioxidative enzymes status, and fungal growth of bread samples incubated under the incubation period were studied. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) studies reveal that the nanocomposite was effectively coated on the packaging material without changing size, shape, and functional groups. No changes in the proximate composition and antioxidative enzymes of the packaged bread samples incubated under different incubation periods reveal the nanocomposite's marked safety. The complete absence of the fungal growth also indicates the uniqueness of the nanocomposite. Further, the sorption studies revealed the utilisation of Langmuir mechanism and pseudo II order model successfully The present finding implies that the synthesised nanocomposite can be used as an effective, safe food preservative agent and adsorbent of toxic chemicals.

In vitro antifungal susceptibility of Fusarium species and Aspergillus fumigatus cultured from eleven horses with fungal keratitis

PURPOSE

To examine the relationship between Minimum Inhibitory Concentration (MICs) and response to therapy of 6 Fusarium spp. and 5 Aspergillus fumigatus isolated from equine ulcerative keratitis cases.

PROCEDURE

Fungi were identified by morphology and Internal Transcribed Spacer (ITS) polymerase chain reaction (PCR) with sequencing and evaluated at the University of Texas Fungal Testing Laboratory for susceptibility to three azole antifungals (miconazole, voriconazole, posaconazole), natamycin, and two echinocandins (anidulafungin, caspofungin). A Mann-Whitney rank sum test was used for the comparison of time to heal between infections of different fungal genera and in vitro susceptibility to the drug administered.

RESULTS

Fusarium spp. were resistant to azole antifungals in 6/6 cases (100%). Fusarium spp. were susceptible to echinocandins and natamycin in all cases. A. fumigatus was resistant to anidulafungin in 1/5 cases (20%) and posaconazole in 1/5 cases (20%) The remainder of A. fumigatus isolates were susceptible to all antifungal agents tested. Fusarium isolates were treated with antifungals to which they were not susceptible; however, all cases of A. fumigatus were treated with antifungals to which they were susceptible. All Fusarium cases and A. fumigatus cases experienced clinical resolution, regardless of surgical intervention. There was no statistical correlation between fungal genus and time to heal (p < .082).

CONCLUSIONS

The in vitro susceptibility indicated that all cases of Fusarium spp. were resistant to azole antifungal drugs which were used as treatment. Clinical outcomes, however, showed that all cases healed despite resistance to antifungals.

CYP51 Mutations in the Fusarium solani Species Complex: First Clue to Understand the Low Susceptibility to Azoles of the Genus Fusarium

Members of Fusarium solani species complex (FSSC) are cosmopolitan filamentous fungi responsible for invasive fungal infections in immunocompromised patients. Despite the treatment recommendations, many strains show reduced sensitivity to voriconazole. The objective of this work was to investigate the potential relationship between azole susceptibility and mutations in CYP51 protein sequences. Minimal inhibitory concentrations (MICs) for azole antifungals have been determined using the CLSI (Clinical and Laboratory Standards Institute) microdilution method on a panel of clinical and environmental strains. CYP51A, CYP51B and CYP51C genes for each strain have been sequenced using the Sanger method. Amino acid substitutions described in multiple azole-resistant Aspergillus fumigatus (mtrAf) strains have been sought and compared with other Fusarium complexes’ strains. Our results show that FSSC exhibit point mutations similar to those described in mtrAf. Protein sequence alignments of CYP51A, CYP51B and CYP51C have highlighted different profiles based on sequence similarity. A link between voriconazole MICs and protein sequences was observed, suggesting that these mutations could be an explanation for the intrinsic azole resistance in the genus Fusarium. Thus, this innovative approach provided clues to understand low azole susceptibility in FSSC and may contribute to improving the treatment of FSSC infection.

Fusarium Keratitis in Taiwan: Molecular Identification, Antifungal Susceptibilities, and Clinical Features

We performed molecular identification and antifungal susceptibilities of pathogens and investigated clinical features of 43 culture-proven Fusarium keratitis cases from 2015–2020 in Taiwan. The pathogens were identified by sequencing of their internal transcribed spacer regions of ribosomal DNA and translation elongation factor 1α gene; their antifungal susceptibilities (to seven agents) were determined by broth microdilution method. We also collected clinical data to compare the drug susceptibilities and clinical features of Fusarium solani species complex (FSSC) isolates with those of other Fusarium species complexes (non-FSSC). The FSSC accounted for 76.7% pathogens, among which F. falciforme (32.6%) and F. keratoplasticum (27.9%) were the most common species. Among clinically used antifungal agents, amphotericin B registered the lowest minimal inhibitory concentration (MIC), and the new azoles efinaconazole, lanoconazole and luliconazole, demonstrated even lower MICs against Fusarium species. The MICs of natamycin, voriconazole, chlorhexidine, lanoconazole, and luliconazole were higher for the FSSC than the non-FSSC, but no significant differences were noted in clinical outcomes, including corneal perforation and final visual acuity. In Taiwan, the FSSC was the most common complex in Fusarium keratitis; its MICs for five tested antifungal agents were higher than those of non-FSSC, but the clinical outcomes did not differ significantly.

Village-integrated eye workers for prevention of corneal ulcers in Nepal (VIEW study): a cluster-randomised controlled trial

BACKGROUND

Corneal ulcers are a common cause of blindness in low-income and middle-income countries, usually resulting from traumatic corneal abrasions during agricultural work. Antimicrobial prophylaxis of corneal abrasions can help prevent corneal ulcers, but delays in the initiation of therapy are frequent. We aimed to assess whether a community-based programme for corneal ulcer prevention would reduce the incidence of corneal ulceration.

METHODS

A cluster-randomised trial was performed in village development committees (VDCs) in Nepal. VDCs in the catchment area of Bharatpur Eye Hospital, Nepal with less than 15 000 people were eligible for inclusion. We randomly assigned (1:1) VDCs to either an intervention group or a control group. In the intervention VDCs, existing female community health volunteers (FCHVs) were trained to diagnose corneal abrasions and provide a 3-day course of ophthalmic antimicrobials to their patients. In the control VDCs, FCHVs did not provide this intervention. Participants were not masked given the nature of the intervention. Both groups were followed up for 3 years for photographic evidence of corneal ulceration. The primary outcome was the incidence of corneal ulceration, determined by masked assessment of corneal photographs. The analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, NCT01969786.

FINDINGS

We assessed 112 VDCs, of which 24 were enrolled. The study was performed between Feb 4, 2014, and Oct 20, 2017. 12 VDCs were randomly assigned to the intervention group and 12 to the control group. 252 539 individuals were included in the study (130 579 in the intervention group and 121 960 in the control group). FCHVs diagnosed and provided antimicrobials for 4777 corneal abrasions. The census identified 289 corneal ulcers among 246 893 person-years in the intervention group (incidence 1·21 cases [95% CI 0·85-1·74] per 1000 person-years) and 262 corneal ulcers among 239 170 person-years in the control group (incidence 1·18 cases [0·82-1·70] per 1000 person-years; incidence rate ratio 1·03 [95% CI 0·63-1·67]; p=0·93). Medication allergy was self-reported in 0·2% of participants.

INTERPRETATION

We did not detect a reduction in the incidence of corneal ulceration during the first 3 years of a community-based corneal ulcer prevention programme. Further study might be warranted in more rural areas where basic eye care facilities are not available.

FUNDING

National Eye Institute.

Killing efficacy of a new hypothermic corneal storage medium against the micro-organisms frequently found in human donor cornea intended for transplantation

Objective

To study the in vitro killing efficacy of Kerasave (AL.CHI.MI.A Srl), a medium provided with amphotericin B tablet for hypothermic storage of human donor corneas, against relevant contaminants associated with postkeratoplasty infections.

Methods and Analysis

The antimicrobial activity of Kerasave was determined after 0, 3 and 14 days of incubation at 2°C-8°C, inoculating Kerasave and the control medium with 10⁵-10⁶ colony forming units (CFU) of Candida albicans (CA), Fusarium solani (FS), Aspergillus brasiliensis (AB), Staphylococcus aureus (SA), Enterococcus faecalis (EF), Bacillus subtilis spizizenii (BS), Pseudomonas aeruginosa (PA), Enterobacter cloacae (EC) and Klebsiella pneumoniae (KP). Log₁₀ reductions at different time intervals were determined by assessing the number of viable CFU using the serial dilution plating technique.

Results

After 3 days, Kerasave induced the highest log₁₀ decrease in the concentrations of KP, PA, CA and EC (5.37, 4.15, 2.97 and 2.67, respectively; all p<0.001). The log₁₀ decreases of SA and EF were 2.27 and 2.11, respectively (all p<0.001). The lowest log₁₀ decrease was observed in BS, AB and FS concentrations (0.25, 0.30 and 0.67, respectively; p<0.001 for BS and AB and p=0.004 for FS). After 14 days, the microbial count of CA, FS, SA, EF, PA and EC further decreased (p=0.006 for FS; p<0.001 for the others).

Conclusion

Kerasave effectively reduced or kept unchanged the microbial concentration of almost all tested strains after 3 days. Thus, this novel medium represents a valuable tool to control the microbial contamination of human donor corneas during hypothermic storage for up to 14 days before transplantation.

Diagnosing Fungal Keratitis and Simultaneously Identifying Fusarium and Aspergillus Keratitis with a Dot Hybridization Array

Fungal keratitis (FK) is one of the most common microbial keratitis, which often leads to poor prognosis as a result of delayed diagnosis. Several studies implied that early differentiation of the two major FK, Fusarium and Aspergillus keratitis, could be helpful in selecting effective anti-fungal regimens. Therefore, a novel dot hybridization array (DHA) was developed to diagnose FK and differentiate Fusarium and Aspergillus keratitis in this study. One hundred forty-six corneal scrapes obtained from one hundred forty-six subjects impressed with clinically suspected FK were used to evaluate the performance of the DHA. Among these patients, 107 (73.3%) patients had actual FK confirmed by culture and DNA sequencing. We found that the DHA had 93.5% sensitivity and 97.4% specificity in diagnosing FK. In addition, this array had 93.2% sensitivity and 93.8% specificity in diagnosing Fusarium keratitis, as well as 83.3% sensitivity and 100% specificity in diagnosing Aspergillus keratitis. Furthermore, it had 83.9% sensitivity and 100% specificity in identifying Fusarium solani keratitis. Thus, this newly developed DHA will be beneficial to earlier diagnosis, more precise treatment, and improve prognosis of FK, by minimizing medical refractory events and surgical needs.

Expression of immune response genes in human corneal epithelial cells interacting with Aspergillus flavus conidia

Background

Aspergillus flavus, one of the causative agents of human fungal keratitis, can be phagocytosed by human corneal epithelial (HCE) cells and the conidia containing phagosomes mature into phagolysosomes. But the immunological responses of human corneal epithelial cells interacting with A. flavus are not clear. In this study, we report the expression of immune response related genes of HCE cells exposed to A. flavus spores using targeted transcriptomics.

Methods

Human corneal epithelial cell line and primary cultures were grown in a six-well plate and used for coculture experiments. Internalization of the conidia was confirmed by immunofluorescence microscopy of the colocalized endosomal markers CD71 and LAMP1. Total RNA was isolated, and the quantity and quality of the isolated RNA were assessed using Qubit and Bioanalyzer. NanoString nCounter platform was used for the analysis of mRNA abundance using the Human Immunology panel. R-package and nSolver software were used for data analysis. KEGG and FunRich 3.1.3 tools were used to analyze the differentially expressed genes.

Results

Different morphotypes of conidia were observed after 6 h of coculture with human corneal epithelial cells and found to be internalized by epithelial cells. NanoString profiling showed more than 20 differentially expressed genes in immortalized human corneal epithelial cell line and more than ten differentially expressed genes in primary corneal epithelial cells. Distinct set of genes were altered in their expression in cell line and primary corneal epithelial cells. KEGG pathway analysis revealed that genes associated with TNF signaling, NF-KB signaling, and Th17 signaling were up-regulated, and genes associated with chemokine signaling and B cell receptor signaling were down regulated. FunRich pathway analysis showed that pathways such as CDC42 signaling, PI3K signaling, and Arf6 trafficking events were activated by the clinical isolates CI1123 and CI1698 in both type of cells.

Conclusions

Combining the transcript analysis data from cell lines and primary cultures, we showed the up regulation of immune defense genes in A. flavus infected cells. At the same time, chemokine signaling and B cell signaling pathways are downregulated. The variability in the expression levels in the immortalized cell line and the primary cultures is likely due to the variable epigenetic reprogramming in the immortalized cells and primary cultures in the absence of any changes in the genome. It highlights the importance of using both cell types in host-pathogen interaction studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-08218-5.

Malignant Keratitis Caused by a Highly-Resistant Strain of Fusarium Tonkinense from the Fusarium Solani Complex

Fusarium spp. are moulds ubiquitously distributed in nature and only occasionally pathogenic for humans. Species of the Fusarium solani complex are the predominant keratitis-inducing pathogens, because they are endowed with proper virulence factors. These fungi can adhere to the cornea creating a biofilm and, with the help of enzymes and cytotoxins, penetrate the cornea. Whereas an intact cornea is hardly able to be invaded by Fusarium spp. in spite of appropriate virulence factors, these opportunistic fungi may profit from predisposing conditions, for example mechanical injuries. This can lead to a progressive course of corneal infection and may finally affect the whole eye up to the need for enucleation. Here, we present and discuss the clinical, microbiological and histopathological aspects of a particular case due to Fusarium tonkinense of the Fusarium solani complex with severe consequences in a patient without any obvious predisposing factors. A broad portfolio of antifungal agents was applied, both topically and systemically as well as two penetrating keratoplasties were performed. The exact determination of the etiologic agent of the fungal infection proved likewise to be very challenging.

Fusarium Keratitis-Review of Current Treatment Possibilities

In many parts of the world, fungi are the predominant cause of infectious keratitis; among which, Fusarium is the most commonly isolated pathogen. The clinical management of this ophthalmic emergency is challenging. Due to the retardation of the first symptoms from an injury and the inability to differentiate fungal from bacterial infections based on clinical symptoms and difficult microbial diagnostics, proper treatment, in many cases, is postponed. Moreover, therapeutical options of Fusarium keratitis remain limited. This paper summarizes the available treatment modalities of Fusarium keratitis, including antifungals and their routes of administration, antiseptics, and surgical interventions.

Eye Infections Caused by Filamentous Fungi: Spectrum and Antifungal Susceptibility of the Prevailing Agents in Germany

Fungal eye infections can lead to loss of vision and blindness. The disease is most prevalent in the tropics, although case numbers in moderate climates are increasing as well. This study aimed to determine the dominating filamentous fungi causing eye infections in Germany and their antifungal susceptibility profiles in order to improve treatment, including cases with unidentified pathogenic fungi. As such, we studied all filamentous fungi isolated from the eye or associated materials that were sent to the NRZMyk between 2014 and 2020. All strains were molecularly identified and antifungal susceptibility testing according to the EUCAST protocol was performed for common species. In total, 242 strains of 66 species were received. Fusarium was the dominating genus, followed by Aspergillus, Purpureocillium, Alternaria, and Scedosporium. The most prevalent species in eye samples were Fusarium petroliphilum, F. keratoplasticum, and F. solani of the Fusarium solani species complex. The spectrum of species comprises less susceptible taxa for amphotericin B, natamycin, and azoles, including voriconazole. Natamycin is effective for most species but not for Aspergillus flavus or Purpureocillium spp. Some strains of F. solani show MICs higher than 16 mg/L. Our data underline the importance of species identification for correct treatment.

Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections

The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.

Clinical characteristics, predisposing factors, and treatment outcome of Curvularia keratitis

Purpose

To report clinical characteristics, predisposing factors, and treatment outcome of Curvularia keratitis.

Methods

Retrospective chart review of consecutive culture-proven Curvularia keratitis patients who presented to a tertiary eye care center in north India. Patients with mixed infections with Curvularia as one of the pathogens were also included. Standard case report form was developed to capture demographic information, clinical features, etiology, treatment, and outcome. Binary logistic regression was done to ascertain the effect of identified variables on final visual acuity.

Results

Medical records of 97 patients of Curvularia keratitis were reviewed. Median age of patients was 45.3 years. Seventy-nine (79.4%) patients presented during the months of September to November. History of corneal trauma was present in 69.1%. Trauma from sugarcane leaf was identified in 66.1% of cases with corneal trauma with vegetative matter. Presenting visual acuity was worse than 20/60 in 57.8% of patients. Hypopyon and pigmented plaque-like infiltrate was present in 16.5% and 28.8% of patients, respectively. Mixed infection was reported in 14.4% of cases. Median time of antifungal therapy was 24.5 days. Surgical intervention was required in 18.5% cases. Of all, 11.1% patients achieved final VA of more than 20/200 who were managed surgically as compared to 68 (86%) patients who were managed medically. Younger age, absence of comorbidities, and lesser infiltrate size were found associated with good final visual acuity.

Conclusion

Working males were most affected by Curvularia keratitis. Corneal trauma with sugarcane leave was the most common predisposing factor in the study area. Most of the cases presented with worse visual acuity but could be managed medically.

Antifungal susceptibility of clinical mould isolates in New Zealand, 2001-2019

The objective of this study was to review the antifungal susceptibility of clinical mould isolates performed by the New Zealand Mycology Reference Laboratory. Isolates were either local or referred for testing from other New Zealand laboratories. All isolates were tested by the broth colorimetric microdilution method, Sensititre YeastOne (SYO). Epidemiological cut-off values (ECVs) derived from either the Clinical and Laboratory Standards Institute (CLSI) method or SYO were used to determine the proportion of non-wild type (non-WT) isolates, i.e., those with an increased likelihood to harbour acquired mechanisms of resistance. A total of 614 isolates were tested. Most isolates (55%) were from the respiratory tract followed by musculoskeletal tissue (17%), eye (10%) and abdomen (5%). The azoles had similar activity except for voriconazole which was less active against the Mucorales. The echinocandins had good activity against Aspergillus spp., other hyaline moulds and dematiaceous isolates but were inactive against Fusarium spp., Lomentospora prolificans and the Mucorales. Amphotericin B had best activity against the Mucorales. The two least susceptible groups were Fusarium spp. and L. prolificans isolates. Three Aspergillus isolates were non-WT for amphotericin B, and four non-WT for azoles. Non-WT were not encountered for caspofungin. Non-Aspergillus isolates in New Zealand have susceptibility patterns similar to those reported elsewhere. In contrast to a growing number of other countries, azole resistance was rare in A. fumigatus sensu stricto. Non-WT isolates were uncommon. The results provide a baseline for monitoring emerging antifungal resistance in New Zealand and support current Australasian treatment guidelines for invasive fungal infections.

Evaluation of antimicrobial properties of a novel synthesized nanometric delafossite

Antibiotics and other antimicrobial compounds are the backbone of clinical medicine. Antimicrobial resistance can cause serious diseases to man. Nanotechnology can improve therapeutic potential of medicinal molecules and related agents. Widespread application of antibiotics and other antimicrobial compounds led to development of multidrug-resistant microbes, so there is need to develop novel therapeutic agents. Novel synthesized nanometric delafossite was assayed against two Gram-positive bacteria (Staphylococcus aureus and Micrococcus luteus), two Gram-negative bacteria (Escherichia coli and Klebsiella pneumoniae), four opportunistic fungi (Aspergillus flavus, A. fumigatus, A. niger, and Fusarium solani), and four Candida species (C. albicans, C. parapsilosis, C. krusei, and C. tropicalis) using diffusion assay method. The minimum inhibitory concentration (MIC) of the novel synthesized nanometric delafossite was determined using the dilution method. The assayed compounds showed different degrees of antifungal and antibacterial activities, depending on the annealing temperature of preparation of these compounds. Compounds prepared at room temperature showed greater antimicrobial activities than those prepared at higher temperatures. The antimicrobial activity depends also on the susceptibility of the test microbe.

In-vitro assessment of first-line antifungal drugs against Aspergillus spp. caused human keratomycoses

BACKGROUND AND OBJECTIVES

Aspergillus keratitis are in the increasing trend and reported as the second most common cause of mycotic keratitis in developing countries. The present study was designed to isolate, identify Aspergillus spp. from the keratits/corneal ulcer patients attending a tertiary care eye hospital, Coimbatore, South India and to assess the minimum inhibitory concentrations (MICs) against ten clinically used first-line antifungal drugs.

METHODS

A total of seventy-three Aspergillus strains isolated from corneal scrapings were included and assessed for a period of one year. All isolates were identified up to the species level by morphological observations. Antifungal drug susceptibilities were determined against a standard panel of antifungal agents.

CONCLUSIONS

Five different species of aspergilli, A. flavus (n=53), A. fumigatus (n=14), A. terreus (n=9), A. tamarii (n=6) and A. niger (n=3) were identified based on morphological features. Minimum inhibitory concentration analyses indicated that, voriconazole, natamycin, itraconazole, clotrimazole, econazole followed by ketoconazole shall be the order of choices for the effective treatment for Aspergillus keratitis.

Histological Effects of Intravitreal Injection of Antifungal Agents in New Zealand White Rabbits: An Electron Microscopic and Immunohistochemical Study

Fungal endophthalmitis is a serious and vision-threatening infection which requires an immediate and effective treatment approach. Our research aims to elucidate the histological effects of the intravitreal injection of the maximum safe dosage of voriconazole and micafungin on retina. Six albino New Zealand White Rabbits were used. In experimental animals, a solution of voriconazole (Group V) or micafungin (Group M) was intravitreally injected in the right eye, while in control animals, balanced salt solution was intravitreally injected in the left eye (Group C). Euthanasia was performed ten days post injection and the retina was removed and prepared for histological examination with a light and electron microscope. Eosin-hematoxylin staining did not reveal any pathological changes in any of the samples examined. The immunohistochemical staining for Tumor Necrosis Factor alpha (TNF-a) marker was detected as negative in all samples, while Interleukin 6 (IL-6) marker was detected as mild only in the group injected with voriconazole. Electron microscopy revealed several ultrastructural alterations in retinal layers in both groups of experimental animals. Histological retinal lesions, revealed with electron microscopy in the present investigation, raises the question of the safe usage of these antifungal agents in the treatment of fungal intraocular infections in the future.

Utility of systemic voriconazole in equine keratomycosis based on pharmacokinetic-pharmacodynamic analysis of tear fluid following oral administration

Objective

To clarify the detailed pharmacokinetics (PK) of orally administered voriconazole in tear fluid (TF) of horses for evaluating the efficacy of voriconazole secreted into TF against equine keratomycosis.

Animals studied

Five healthy Thoroughbred horses.

Procedures

Voriconazole was administrated through a nasogastric tube to each horse at a single dose of 4.0 mg/kg. TF and blood samples were collected before and periodically throughout the 24 hours after administration. Voriconazole concentrations in plasma and TF samples were analyzed using liquid chromatography‐electrospray tandem‐mass spectrometry. The predicted voriconazole concentration in both samples following multiple dosing every 24 hours was simulated by the superposition principle.

Results

The mean maximum voriconazole concentrations in plasma and TF were 3.3 μg/mL at 1.5 h and 1.9 μg/mL at 1.6 h, respectively. Mean half‐life in both samples were 16.4 and 25.2 h, respectively. The ratio of predicted AUC_0–24 at steady state in TF (51.3 μg∙h/mL) to previously published minimum inhibitory concentration (MIC) of Aspergillus and Fusarium species was >100 and 25.7, respectively.

Conclusions

This study demonstrated the detailed single‐dose PK of voriconazole in TF after oral administration and simulated the predicted concentration curves in a multiple oral dosing. Based on the analyses of PK‐PD, the simulation results indicated that repeated oral administration of voriconazole at 4.0 mg/kg/d achieves the ratio of AUC to MIC associated with treatment efficacy against Aspergillus species. The detailed PK‐PD analyses against pathogenic fungi in TF can be used to provide evidence‐based medicine for equine keratomycosis.

Luliconazole, a highly effective imidazole, against Fusarium species complexes

Luliconazole is a new antifungal that was primarily used for the treatment of dermatophytosis. However, some studies have shown that it has excellent efficacy against Aspergillus and Candida species in vitro. The present study aimed to evaluate of luliconazole activity against some Fusarium species complex isolates. In this study, 47 isolates of Fusarium were tested against several antifungals including luliconazole. All species were identified using morphology features, and PCR sequencing and antifungal susceptibility were performed according to CLSIM38 A3 guideline. Our results revealed that luliconazole has a very low minimum inhibitory concentration value (0.0078-1 µg/ml) in comparison with other tested antifungals. Amphotericin B had a poor effect with a high MIC₉₀ (64 µg/ml), followed by terbinafine (32 µg/ml), posaconazole (16 µg/ml), caspofungin (16 µg/ml), voriconazole (4 µg/ml), and itraconazole (4 µg/ml). Overall, our findings indicated that luliconazole has great activity against environmental and clinical Fusarium species complexes in comparison to tested antifungals.

Natamycin and Voriconazole Exhibit Synergistic Interactions with Nonantifungal Ophthalmic Agents against Fusarium Species Ocular Isolates

The in vitro activities of two antifungal drugs in combination with four nonantifungal ophthalmic agents were evaluated using a broth microdilution method and a collection of eight Fusarium ocular isolates that exhibited resistance to both natamycin (MICs, 14 to 32 μg/ml) and voriconazole (MICs, 4 to >128 μg/ml). Synergistic and indifferent interactions were observed for natamycin and 5-fluorouracil and natamycin with timolol dependent on the Fusarium isolate tested. Isolate-dependent synergistic and indifferent interactions were also observed for natamycin with EDTA and natamycin with dorzolamide. Synergistic or indifferent interactions were observed for voriconazole with timolol and voriconazole with 5-fluorouracil depending on Fusarium isolate. Taken together, these data suggest that commonly used ophthalmic agents enhance the in vitro activity of antifungal drugs against drug-recalcitrant ocular fungal pathogens.

Efficacy of Luliconazole Against Broad-Range Filamentous Fungi Including Fusarium solani Species Complex Causing Fungal Keratitis

PURPOSE

Fungal keratitis can be difficult to medically treat. Topical antifungals are usually applied empirically as the initial option in treating fungal keratitis. Natamycin (NAT) and/or voriconazole (VRCZ) have been widely used in the treatment of fungal keratitis. However, Fusarium solani species complex (FSSC), which are the dominant species of fungal keratitis, are resistant to VRCZ. This study investigated in vitro efficacy of luliconazole (LLCZ), a new imidazole antifungal, against FSSC and other filamentous fungi.

METHODS

A total of 18 Fusarium isolates and 7 others were grown on potato dextrose agar at 30 and 37°C. For Fusarium, species identification and phylogenetic tree analysis were performed based on elongation factor-1α (EF-1α) DNA sequencing. The broth microdilution method was used for antifungal susceptibility testing of 11 antifungal drugs including LLCZ.

RESULTS

The 18 identified Fusarium isolates belonged to FSSC (n = 13), Fusarium oxysporum species complex (FOSC; n = 2), Fusarium chlamydosporum species complex (FCSC; n = 1), Fusarium incarnatum-equiseti species complex (FIESC; n = 1), and Fusarium fujikuroi species complex (FFSC; n = 1). We further divided 13 FSSC isolates into 3 clades, FSSC5 (n = 8), FSSC3 + 4 (n = 4), and FSSC9-a (n = 1), with 8 FSSC strains growing at 37°C. LLCZ showed lowest minimum inhibitory concentrations (MICs) against all tested filamentous fungi, with a MIC90 against the Fusarium species of 0.06 μg/mL, whereas MIC90 for NAT and VRCZ were 4 and 8 μg/mL, respectively.

CONCLUSIONS

LLCZ has the strongest in vitro antifungal activity among all drugs used against broad-range filamentous fungi including FSSC. LLCZ may potentially be a new medical treatment option for fungal keratitis.

Fungal Keratitis: Epidemiology, Rapid Detection, and Antifungal Susceptibilities of Fusarium and Aspergillus Isolates from Corneal Scrapings

Fungal aetiology of keratitis/corneal ulcer is considered to be one of the leading causes of ocular morbidity, particularly in developing countries including India. More importantly, Fusarium and Aspergillus are reported commonly implicating corneal ulcer and against this background the present work was undertaken so as to understand the current epidemiological trend of the two fungal keratitis. During the project period, a total of 500 corneal scrapings were collected from suspected mycotic keratitis patients, of which 411 (82.2%) were culture positive for bacteria, fungi, and parasites. Among fungal aetiologies, Fusarium (216, 52.5% of 411) and Aspergillus (68, 16.5% of 411) were predominantly determined. While the study revealed a male preponderance with both the fungal keratitis , it further brought out that polyene compounds (natamycin and amphotericin B) and azoles were active, respectively, against Fusarium spp. and Aspergillus spp. Additionally, 94.1% of culture proven Fusarium keratitis and, respectively, 100% and 63.6% of A. flavus and A. fumigatus were confirmed by multiplex PCR. The sensitivity of the PCR employed in the present study was noted to be 10 fg/μl, 1 pg/μl, and 300 pg/μl of DNA, respectively, for Fusarium, A. flavus, and A. fumigatus. Alarming fact was that Fusarium and Aspergillus regionally remained to be the common cause of mycotic keratitis and the Fusarium isolates had a higher antifungal resistance than Aspergillus strains against most of the test drugs.

Epidemiology of Aspergillus species causing keratitis in Mexico

BACKGROUND

The incidence of fungal keratitis has increased in recent years. While the epidemiology and clinical roles of various Candida and Fusarium species have been relatively well-identified in infections of the eye, data regarding keratitis caused by Aspergillus species are scant. Accurate and rapid diagnosis is important for successful management of this infection.

OBJECTIVES

To present the first molecular epidemiological data from Mexico during a 4-year period of cases admitted with Aspergillus keratitis to a tertiary care eye institution in Mexico City.

PATIENTS/METHODS

A total of 25 cases of keratitis were included in the study. Aspergillus isolates were identified by sequencing the calmodulin gene. Antifungal susceptibility was tested according to CLSI.

RESULTS

The aetiological agents belonged to Aspergillus flavus (n = 13), Aspergillus effusus (n = 1), Aspergillus tamarii (n = 4), Aspergillus sydowii (n = 1), Aspergillus protuberus (n = 3) and Aspergillus terreus (n = 3). All strains had low minimum inhibitory concentrations (MICs) of itraconazole and voriconazole (VCZ). Amphotericin B and natamycin showed moderate elevated MICs.

CONCLUSIONS

Early diagnosis and application of topical VCZ 1% were associated with good outcome. Monitoring of local epidemiological data plays an important role in clinical practice.

Fungal keratitis: An overview of clinical and laboratory aspects

Mycotic keratitis or keratomycosis is a fungal infection with global distribution. The dominant aetiology of this disease varies based on geographical origin, socioeconomic status, and climatic condition. Generally, Aspergillus spp. and Fusarium spp. are common in tropical and subtropical regions and Candida spp. are dominant in temperate areas. Demonstration of fungal elements in microscopic examination besides the isolation of fungi in culture is the gold standard of laboratory diagnosis. As the culture is a time-consuming procedure, other approaches such as in vivo confocal microscopy which produces real-time imaging of corneal tissue and molecular techniques have been developed to facilitate rapid diagnosis of fungal keratitis. The first choice of treatment is topical natamycin, although topical amphotericin B is the best choice for Aspergillus and Candida keratitis. Regarding the diversity of fungal aetiology and the emergence of drug resistance in some genera and species, proper identification using molecular methods and antifungal susceptibility testing could provide useful data. Furthermore, as the better efficacy of combination therapy in comparison to monotherapy is reported, in vitro determination of interactions between various drugs seem informative. This review aims to provide a general and updated view on the aetiology, risk factors, epidemiology, clinical and laboratory diagnosis, and management of fungal keratitis.

Natamycin and Azithromycin Are Synergistic In Vitro against Ocular Pathogenic Aspergillus flavus Species Complex and Fusarium solani Species Complex Isolates

The interaction of natamycin-azithromycin combination against 60 ocular fungal isolates was tested in vitro The combination produced 100% synergistic interactions when natamycin was added to azithromycin 20, 40, and 50 μg/ml against Aspergillus flavus species complex (AFSC) isolates and to azithromycin 50 μg/ml against Fusarium solani species complex isolates. Addition of 50 μg/ml azithromycin enhanced natamycin's effect against AFSC isolates by reducing natamycin MIC₉₀ from 64 to 0.031 μg/ml. No antagonism was observed.

Ocular infections caused by Scedosporium apiospermum: A case series

The aim of our retrospective study is to report a case series of ocular infections caused by a rare fungus, Scedosporium apiospermum, in a South Indian population. Thirteen cases of culture-positive S. apiospermum infections diagnosed between January 2011 and March 2016 were included in this study. The parameters evaluated were predisposing factors, treatment and final clinical outcome. The most common mode of presentation was keratitis (84.6%) followed by sclerokeratitis (15.3%). The predisposing factors involved were unspecified foreign body injury (30.7%), organic matter injury (15.3%), uncontrolled diabetes (7.6%), and recent manual small-incision cataract surgery (7.6%). Five cases (38.46%) had no predisposing factor. Of the 11 keratitis cases, nine (69.2%) responded well to combination medical therapy while one case (7.6%) required therapeutic keratoplasty. One case was lost to follow-up. Both cases which presented with sclerokeratitis showed no response to medico-surgical treatment progressing to panophthalmitis and evisceration.

[Fungal keratitis: A 5-year monocentric retrospective study on Reunion Island]

OBJECTIVES

Fungal keratitis is rare in France, but could be a severe sight-threatening condition. Here, we aimed to describe the epidemiology of fungal keratitis in Réunion Island.

METHODS

In a retrospective study, we analyzed 13 culture-proven keratitis episodes, occurred between January 2013 and July 2017 in the ophthalmology ward of a University Hospital, Saint-Pierre. Twelve isolates were genotyped and antifungal susceptibility testing was performed.

RESULTS

Corneal abrasion caused by vegetable matter was the main predisposing factor. Stromal infiltration was observed in 12 patients. Six patients did not response to medical treatment, requiring surgical care, including two enucleations surgery. Fusarium solani (n = 6) and Fusarium dimerum (n = 4) were the main fungal species involved in fungal keratitis. Clinical failures were more prevalent with F. solani infections. The lowest minimal inhibitory concentrations for Fusarium sp. were observed with voriconazole and amphotericin B.

CONCLUSION

In Reunion Island, the epidemiology of fungal keratitis is characterized by the predominance of Fusarium species, potentially involved in visual loss. This pattern is consistent with the epidemiology usually observed in tropical areas.

Fungal keratitis: The Aravind experience

Research becomes very significant and meaningful when it addresses a significant public health problem of a region. Fungal keratitis is a serious problem affecting the agrarian poor and hence requires attention from public health specialists. The approach to a public health issue should focus not only on treatment but also prevention or at least show a significant thrust to reduce the morbidity of the problem. At our institution, we have developed a special interest in fungal keratitis and tried to study it in a multitude of aspects. As we put the pieces of the puzzle together, we believe that interest will be rekindled among policymakers, clinicians, microbiologists, pharmaceutical industry, and basic scientists to work together to join forces and take up an integrative approach to managing this problem. It is also believed that the article underscores the need and importance of having a focused approach to ensuring a successful career in clinical research.

Effect of itraconazole on the cornea in a murine suture model and penetrating keratoplasty model

AIM

To investigate the anti-(lymph)angiogenic and/or anti-inflammatory effect of itraconazole in a corneal suture model and penetrating keratoplasty (PK) model.

METHODS

Graft survival, corneal neovascularization, and corneal lymphangiogenesis were compared among itraconazole, amphotericin B, dexamethasone, phosphate buffered saline (PBS) and surgery-only groups following subconjunctival injection in mice that underwent PK and corneal suture. Immunohistochemical staining and analysis were performed in each group. Real-time polymerase chain reaction (RT-PCR) was performed to quantify the expression of inflammatory cytokines (TNF-alpha, IL-6) and vascular endothelial growth factor (VEGF)-A, VEGF-C, VEGFR-2, and VEGFR-3.

RESULTS

In the suture model, the itraconazole group showed less angiogenesis, less lymphangiogenesis, and less inflammatory infiltration than the PBS group (all P<0.05). The itraconazole group showed reduced expression of VEGF-A, VEGFR-2, TNF-alpha, IL-6 than the PBS group (all P<0.05). In PK model, the two-month graft survival rate was 28.57% in itraconazole group, 62.50% in dexamethasone group, 12.50% in PBS group, 0 in amphotericin B group and 0 in surgery-only group. Graft survival in the itraconazole group was higher than that in the amphotericin, PBS and surgery-only group (P=0.057, 0.096, 0.012, respectively). The itraconazole group showed less total angiogenesis and lymphangiogenesis than PBS group (all P<0.05).

CONCLUSION

Itraconazole decrease neovascularization, lymphangiogenesis, and inflammation in both a corneal suture model and PK model. Itraconazole has anti-(lymph)-angiogenic and anti-inflammatory effects in addition to its intrinsic antifungal effect and is therefore an alternative treatment option in cases where steroids cannot be used.

Fusarium Keratitis in Germany

Fusarium keratitis is a destructive eye infection that is difficult to treat and results in poor outcome. In tropical and subtropical areas, the infection is relatively common and associated with trauma or chronic eye diseases. However, in recent years, an increased incidence has been reported in temperate climate regions. At the German National Reference Center, we have observed a steady increase in case numbers since 2014. Here, we present the first German case series of eye infections with Fusarium species. We identified Fusarium isolates from the eye or eye-related material from 22 patients in 2014 and 2015. Thirteen isolates belonged to the Fusarium solani species complex (FSSC), 6 isolates belonged to the Fusarium oxysporum species complex (FOSC), and three isolates belonged to the Fusarium fujikuroi species complex (FFSC). FSSC was isolated in 13 of 15 (85%) definite infections and FOSC in 3 of 4 (75%) definite contaminations. Furthermore, diagnosis from contact lens swabs or a culture of contact lens solution turned out to be highly unreliable. FSSC isolates differed from FOSC and FFSC by a distinctly higher MIC for terbinafine. Outcome was often adverse, with 10 patients requiring keratoplasty or enucleation. The use of natamycin as the most effective agent against keratitis caused by filamentous fungi was rare in Germany, possibly due to restricted availability. Keratitis caused by Fusarium spp. (usually FSSC) appears to be a relevant clinical problem in Germany, with the use of contact lenses as the predominant risk factor. Its outcome is often adverse.

Recent advances in diagnosis and management of Mycotic Keratitis

Mycotic keratitis is a major cause of corneal blindness, especially in tropical and subtropical countries. The prognosis is markedly worse compared to bacterial keratitis. Delayed diagnosis and scarcity of effective antifungal agents are the major factors for poor outcome. Over the last decade, considerable progress has been made to rapidly diagnose cases with mycotic keratitis and increase the efficacy of treatment. This review article discusses the recent advances in diagnosis and management of mycotic keratitis with a brief discussion on rare and emerging organisms. A MEDLINE search was carried out for articles in English language, with the keywords, mycotic keratitis, fungal keratitis, emerging or atypical fungal pathogens in mycotic keratitis, investigations in mycotic keratitis, polymerase chain reaction in mycotic keratitis, confocal microscopy, treatment of mycotic keratitis, newer therapy for mycotic keratitis. All relevant articles were included in this review. Considering the limited studies available on newer diagnostic and therapeutic modalities in mycotic keratitis, case series as well as case reports were also included if felt important.

Current antifungal treatment of fusariosis

Fungi of the genus Fusarium are well known as major plant pathogens and soil inhabitants, but also cause a broad spectrum of human infections. Fusariosis is the second most common mould infection after aspergillosis, and keratitis is the most encountered implantation infection in immunocompetent individuals. Natamycin is active against Fusarium species both in vitro and in vivo, and is used along with voriconazole as the mainstay of treatment for Fusarium keratitis. Onychomycosis is treated with terbinafine, voriconazole and sometimes itraconazole. Cure is possible despite high in vitro minimum inhibitory concentrations (MICs). Recently, disseminated infections have increased dramatically, mainly affecting severely immunocompromised patients. The remarkable intrinsic resistance of Fusarium species to most antifungal agents results in high mortality rates in this patient population. Recovery of neutropenia is essential for patient survival and treatment should include voriconazole or amphotericin B as first-line and posaconazole as salvage therapy.

Invasive fungal infection in patients with hematologic disorders in a Brazilian tertiary care hospital

INTRODUCTION:

Invasive fungal infections (IFIs) are an important complication in immunocompromised individuals, particularly neutropenic patients with hematological malignancies. In this study, we aimed to verify the epidemiology and diagnosis of IFIs in patients with hematologic problems at a tertiary hospital in Goiânia-GO, Brazil.

METHODS:

Data from 117 patients, involving 19 cases of IFIs, were collected. The collected data included diagnosis methods, demographics, clinical characteristics, and in vitro susceptibility to different antifungal agents. Among the 19 cases, 12 were classified as proven IFI and 7 as probable invasive aspergillosis with detection of galactomannan in blood and presence of lung infiltrates in radiographic images. Logistic regression analysis showed that the proven and probable IFIs were associated with increased risk of death. Statistical analysis demonstrated that age, sex, and underlying disease were not independently associated with risk of death in IFI patients.

RESULTS:

Most bloodstream isolates of Candida spp. exhibited low minimum inhibitory concentrations (MICs) to all antifungal agents tested. Voriconazole and amphotericin had the lowest MICs for Aspergillus spp. and Fusarium spp., but Fusarium spp. showed the least susceptibility to all antifungals tested. Amphotericin B, fluconazole, and itraconazole were found to be inactive in vitro against Acremonium kiliense; but this fungus was sensitive to voriconazole.

CONCLUSIONS:

Considering the high number of IFI cases, with crude mortality rate of 6%, we could conclude that IFIs remain a common infection in patients with hematological malignancies and underdiagnosed ante mortem. Thus, IFIs should be monitored closely.

Antifungal Susceptibility Testing of Fusarium: A Practical Approach

In vitro susceptibility testing of Fusarium is becoming increasingly important because of frequency and diversity of infections and because resistance profiles are species-specific. Reference methods for antifungal susceptibility testing (AFST) are those of Clinical and Laboratory Standards Institute (CLSI) and European Committee on Antimicrobial Susceptibility (EUCAST), but breakpoints (BPs) have not yet been established. One of the problems is that phylogenetic distances between Fusarium species are much smaller than between species of, e.g., Candida. Epidemiological cutoff values (ECVs) for some Fusarium species have been determined in order to differentiate wild-type from non-wild-type isolates. In clinical routine, commercially available assays such as Etest, Sensititre or others provide essential agreement with reference methods. Our objective is to summarize antifungal susceptibility testing of Fusarium genus in the clinical laboratory: how to do it, when to do it, and how to interpret it.

Fusarium Endophthalmitis following Cataract Surgery: Successful Treatment with Intravitreal and Systemic Voriconazole

Purpose. To report a case of postoperative endophthalmitis caused by Fusarium species successfully treated with intravitreal and systemic voriconazole after treatment failure with amphotericin B. Methods. Clinical case report of a 60-year-old immunocompetent woman who presents with endophthalmitis of unknown origin 4 weeks after uneventful cataract extraction and IOL implantation surgery. IOL explantation, vitrectomy with capsular bag removal, vitreous aspiration for culture, and intravitreal injection of amphotericin B (5 μg/0.1 mL) were performed. Diagnosis was established by culturing the vitreous aspirate on a Sabouraud agar medium and staining with lactophenol blue solution. Five days later, there was no clinical response. The decision was made to administer a single dose of intravitreal voriconazole (2.5 μg/0.1 mL) and oral voriconazole (200 mg BID) for 30 days. Results. Fusarium sp. grew on culture. Treatment with local and systemic voriconazole was started after no improvement with vitrectomy, IOL explantation, and intravitreal amphotericin B. After 1 month of treatment, the infection resolved and best-corrected visual acuity was 20/25. Conclusion. In patients with endophthalmitis caused by Fusarium sp., topical and systemic voriconazole treatment should be considered in cases resistant to intravitreal amphotericin B.

Antifungal Susceptibility and Phylogeny of Opportunistic Members of the Genus Fusarium Causing Human Keratomycosis in South India

Fusarium species are reported frequently as the most common causative agents of fungal keratitis in tropical countries such as India. Sixty-five fusaria isolated from patients were subjected to multilocus DNA sequencing to characterize the spectrum of the species associated with keratitis infections in India. Susceptibilities of these fusaria to ten antifungals were determined in vitro by the broth microdilution method. An impressive phylogenetic diversity of fusaria was reflected in susceptibilities differing at species level. Typing results revealed that the isolates were distributed among species in the species complexes (SCs) of F. solani (FSSC; n = 54), F. oxysporum (FOSC; n = 1), F. fujikuroi (FFSC; n = 3), and F. dimerum (FDSC; n = 7). Amphotericin B, voriconazole, and clotrimazole proved to be the most effective drugs, followed by econazole.

Time-Kill Kinetics and In Vitro Antifungal Susceptibility of Non-fumigatus Aspergillus Species Isolated from Patients with Ocular Mycoses

Aspergillus species can cause ocular morbidity and blindness, and thus, appropriate antifungal therapy is needed. We investigated the in vitro activity of itraconazole, voriconazole, posaconazole, caspofungin, anidulafungin, and amphotericin B against 14 Aspergillus isolates obtained from patients with ocular mycoses, using the CLSI reference broth microdilution methodology. In addition, time-kill assays were performed, exposing each isolate separately to 1-, 4-, and 16-fold concentrations above the minimum inhibitory concentration (MIC) of each antifungal agent. A sigmoid maximum-effect (E_max) model was used to fit the time-kill curve data. The drug effect was further evaluated by measuring an increase/decrease in the killing rate of the tested isolates. The MICs of amphotericin B, itraconazole, voriconazole, and posaconazole were 0.5–1.0, 1.0, 0.5–1.0, and 0.25 µg/ml for A. brasiliensis, A. niger, and A. tubingensis isolates, respectively, and 2.0–4.0, 0.5, 1.0 for A. flavus, and 0.12–0.25 µg/ml for A. nomius isolates, respectively. A. calidoustus had the highest MIC range for the azoles (4.0–16.0 µg/ml) among all isolates tested. The minimum effective concentrations of caspofungin and anidulafungin were ≤0.03–0.5 µg/ml and ≤0.03 µg/ml for all isolates, respectively. Posaconazole demonstrated maximal killing rates (E_max = 0.63 h⁻¹, r² = 0.71) against 14 ocular Aspergillus isolates, followed by amphotericin B (E_max = 0.39 h⁻¹, r² = 0.87), voriconazole (E_max = 0.35 h⁻¹, r² = 0.098), and itraconazole (E_max = 0.01 h⁻¹, r² = 0.98). Overall, the antifungal susceptibility of the non-fumigatusAspergillus isolates tested was species and antifungal agent dependent. Analysis of the kinetic growth assays, along with consideration of the killing rates, revealed that posaconazole was the most effective antifungal against all of the isolates.

Biotechnological production and application of the antibiotic pimaricin: biosynthesis and its regulation

Pimaricin (natamycin) is a small polyene macrolide antibiotic used worldwide. This efficient antimycotic and antiprotozoal agent, produced by several soil bacterial species of the genus Streptomyces, has found application in human therapy, in the food and beverage industries and as pesticide. It displays a broad spectrum of activity, targeting ergosterol but bearing a particular mode of action different to other polyene macrolides. The biosynthesis of this only antifungal agent with a GRAS status has been thoroughly studied, which has permitted the manipulation of producers to engineer the biosynthetic gene clusters in order to generate several analogues. Regulation of its production has been largely unveiled, constituting a model for other polyenes and setting the leads for optimizing the production of these valuable compounds. This review describes and discusses the molecular genetics, uses, mode of action, analogue generation, regulation and strategies for increasing pimaricin production yields.

Unpredictable susceptibility of emerging clinical moulds to tri-azoles: review of the literature and upcoming challenges for mould identification

Tri-azoles represent the front-line drugs for the treatment of mould diseases; nevertheless, some emerging moulds, such as Fusarium spp., Scedosporium spp., Mucorales and others, may be less susceptible or resistant to these antifungals. A review of the literature was conducted on the susceptibility of rare moulds to the tri-azoles itraconazole, posaconazole and voriconazole. Particular attention was paid to isolates identified by molecular analyses. The range of susceptibility values described for the three tri-azoles was frequently large (from 0.06 to >16), and a high variability was found within each species; isolates were rarely reported as entirely susceptible to all tri-azoles. In addition, the susceptibility of 76 emerging moulds from our collection (including Hypocreales, Dothideomycetes, Scedosporium spp., Mucorales and rare Aspergillus spp.) to itraconazole and voriconazole was determined by the Clinical and Laboratory Standards Institute (CLSI) M38-A2 and European Committee for Antimicrobial Susceptibility Testing (EUCAST) methods. Susceptibility discrepancies (of two dilutions) were found comparing CLSI and EUCAST for Dothideomycetes; the values for the remaining moulds were similar. More practical, faster and inexpensive susceptibility tools are welcome for testing emerging moulds, as these tests still represent a critical tool to support clinicians on the selection of proper antifungal treatment. The susceptibility of emerging moulds to tri-azoles cannot be predicted exclusively following mould identification, as the isolates' susceptibilities showed highly variable values. Some emerging moulds still remain very difficult to identity, even following standard molecular analyses which result in complex fungal collections. This fact limits the definition of epidemiological cut-offs and clinical breakpoints that are still imperative for emerging moulds.

Re-appraisal of topical 1% voriconazole and 5% natamycin in the treatment of fungal keratitis in a randomised trial

PURPOSE

To compare the efficacy of topical 1% voriconazole vs 5% natamycin for the treatment of fungal keratitis.

METHODS

In a prospective, double-masked, randomised, controlled, registered clinical trial, 118 patients with fungal keratitis were treated using identical dosage schedule with either voriconazole (58) or natamycin (60) as inpatients for 7 days and followed up weekly. The outcome measures were percentage of patients with healed or resolving ulcer and final visual acuity at last follow-up (primary) and on day 7 (secondary) in each group.

RESULTS

More patients (p=0.005) on natamycin (50/56, 89.2%) had healed or resolving ulcer compared with voriconazole (34/51, 66.6%) at last follow-up. The improvement in vision was marginally greater in patients in the natamycin group compared with the voriconazole group at day 7 (p=0.04) and significantly greater at final visit (p=0.01). In univariate analysis, drug, age and mean size of corneal infiltrate and epithelial defect had a significant effect on the final visual outcome. In multivariate analysis, the effect of drug (voriconazole vs natamycin, adjusted coefficient 0.27 (-0.04 to 0.57), p=0.09) was marginal while the effect of age and epithelial defect was significant (p<0.001 for both). In the group treated with natamycin, the final visual acuity was significantly better (p=0.005, Wilcoxon signed-rank test) in patients with Fusarium keratitis but not with Aspergillus keratitis (p=0.714, paired t test).

CONCLUSIONS

When compared with voriconazole, natamycin was more effective in the treatment of fungal keratitis, especially Fusarium keratitis.

TRIAL REGISTRATION NUMBER

Clinical Trial Registry India (2010/091/003041).