Determination of in vitro susceptibility of ocular Fusarium spp. isolates from keratitis cases and comparison of Clinical and Laboratory Standards Institute M38-A2 and E test methods

Design, Synthesis, and Biological Evaluation of N'-Phenylhydrazides as Potential Antifungal Agents

Fifty-two kinds of N'-phenylhydrazides were successfully designed and synthesized. Their antifungal activity in vitro against five strains of C. albicans (Candida albicans) was evaluated. All prepared compounds showed varying degrees of antifungal activity against C. albicans and their MIC80 (the concentration of tested compounds when their inhibition rate was at 80%), TAI (total activity index), and TSI (total susceptibility index) were calculated. The inhibitory activities of 27/52 compounds against fluconazole-resistant fungi C. albicans 4395 and 5272 were much better than those of fluconazole. The MIC80 values of 14/52 compounds against fluconazole-resistant fungus C. albicans 5122 were less than 4 μg/mL, so it was the most sensitive fungus (TSIB = 12.0). A11 showed the best inhibitory activity against C. albicans SC5314, 4395, and 5272 (MIC80 = 1.9, 4.0, and 3.7 μg/mL). The antifungal activities of B14 and D5 against four strains of fluconazole-resistant fungi were better than those of fluconazole. The TAI values of A11 (2.71), B14 (2.13), and D5 (2.25) are the highest. Further exploration of antifungal mechanisms revealed that the fungus treated with compound A11 produced free radicals and reactive oxygen species, and their mycelium morphology was damaged. In conclusion, the N'-phenylhydrazide scaffold showed potential in the development of antifungal lead compounds. Among them, A11, B14, and D5 demonstrated particularly promising antifungal activity and held potential as novel antifungal agents.

Fusariosis in cancer patients: 13 case series report and literature review

The fusariosis is an opportunistic mycosis caused by Fusarium spp. Its clinical presentation depends on the immunological status of the host, especially in patients with hematooncological diseases, whose manifestations vary from localized to invasive fungal infections. Skin or blood culture helps to guide combined antifungal treatment with amphotericin B and voriconazole. Here, we present 13 cases in a period of eleven years of patients with cancer who developed disseminated fusariosis and their outcomes, together with a review of the related literature. In this series of cases, mortality was 61.5 % (8/13), despite the use of the antifungal. Out of the 13 cases, 11 had hematological neoplasia and 2 solid neoplasia. The most determinant risk factor was profound neutropenia. Skin involvement and positive blood cultures in most cases allowed combined treatment prescription. Persistent febrile neutropenia associated with skin lesions, onychomycosis, nodules, or lung masses lead to suspicion of Fusarium spp. fungal invasive infection. The aim of this series of cases is to remind healthcare professionals that oncological patients with deep and persistent febrile neutropenia can develop fusariosis.

Evaluation of antifungal susceptibility and clinical characteristics in fungal keratitis in a tertiary care center in North India

Purpose

To study the antifungal susceptibility of common corneal pathogenic fungi to antifungal agents in the North Indian population.

Methods

Prospective study of the antifungal sensitivity testing (natamycin, amphotericin B, voriconazole, itraconazole, fluconazole, posaconazole, caspofungin, micafungin) of fungal isolates from 50 cases of culture positive fungal keratitis by using E test method. Details noted included demographic data, visual acuity, clinical details, grade of keratitis, healing time, and success in medical management.

Results

Of 50 patients with fungal keratitis (mean age: 40.28 ± 16.77 years), 12 eyes healed within 3 weeks, 14 had a delayed healing response, and 24 had chronic keratitis. Among the 15 cases of Fusarium isolates, 93.3% were sensitive to natamycin, while 40% to amphotericin B; 66.6% to voriconazole, 13.4% to itraconazole and fluconazole each. 80% of Fusarium cases (n = 12) showed susceptibility to posaconazole. Among Aspergillus flavus isolates, 53.4% (n = 8) were sensitive to natamycin, with only 40% (n = 7) showing sensitivity to amphotericin B and good susceptibility to azoles. MIC against susceptible Fusarium spp. for natamycin was 3-16 μg/mL, amphotericin B: 1-8 μg/mL, voriconazole: 0.5-1.5 μg/mL, itraconazole: 0.5-12 μg/mL, posaconazole: 0.094-1.5 μg/mL. MIC against Aspergillus flavus was natamycin: 8-32 μg/mL, amphotericin B: 0.5-16 μg/mL, voriconazole: 0.025-4 μg/mL, itraconazole: 0.125-8 μg/mL, posaconazole: 0.047-0.25 μg/mL; against Aspergillus niger isolates, to natamycin was 6 μg/mL (n=1), amphotericin B 8-12 μg/mL (n = 3), voriconazole: 0.125-0.19 μg/mL (n = 3), itraconazole: 0.38-0.75 μg/mL, posaconazole: 0.064-0.19 μg/mL and against Aspergillus fumigatus (n = 1), was natamycin4 μg/mL, amphotericin B - 8 μg/mL, voriconazole 0.25 μg/mL, itraconazole 1 μg/mL, and posaconazole 0.19 μg/mL. MIC against susceptible Acremonium spp. for natamycin was 1.5-16 μg/mL, amphotericin B: 0.5-8 μg/mL, voriconazole: 0.19-3 μg/mL, itraconazole: 0.125 μg/mL, posaconazole: 0.125-0.5 μg/mL and against susceptible Curvularia was natamycin 0.75-4 μg/mL, amphotericin B 0.5-1 μg/mL, voriconazole 0.125-0.19 μg/mL, itraconazole 0.047-0.094 μg/mL, posaconazole 0.047-0.094 μg/mL. MIC against Mucor spp.+ Rhizopus spp. (n = 1) was natamycin: 8 μg/mL, amphotericin B: 0.75 μg/mL, posaconazole: 1.5 μg/mL. MIC against of Alternaria (n = 1) was voriconazole: 0.19 μg/mL, posaconazole: 0.094 μg/mL. MIC against Penicillium (n=1) was natamycin: 8 μg/mL, voriconazole: 0.25 μg/mL, itraconazole: 0.5 μg/mL, and Posaconazole: 0.125 μg/mL.

Conclusion

Our observations highlight the variations in susceptibility to antifungal agents. Posaconazole seems to be effective with low MIC against common corneal pathogenic fungal isolates.

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.

Bioavailability enhancement of voriconazole using liposomal pastilles: Formulation and experimental design investigation

Oral mucosa offers several advantages in the delivery of therapeutic molecules. It avoids presystemic metabolism, Nanoencapsulation techniques might be applied to conquer physical, chemical challenges and enhance drug penetration, formulation performance, prolonging drug residence time, and improving sensorial feeling. The present investigation is aimed to formulate liposomal pastilles with high bioavailability. Voriconazole Liposomes (VL) were produced by utilizing varied ratios of soya lecithin (SL) and cholesterol (CH) by solvent Injection method. RSM is utilized to identify the optimized formulation, as this design provides a thorough understanding of a process and also has great utilization in originating the robustness of the product. The main impact and interaction terms of the formulation variables were assessed quantitatively utilizing a mathematical-statistical approach indicating that both independent variables have significant ('P' value < 0.05) effects on particle size ('P' value: 0.0142), percentage entrapment efficiency ('P' value: 0.0120), percentage drug release through the dialysis membrane ('P' value: 0.0105), percentage drug release through porcine buccal mucosa ('P' value: 0.0171) and percentage zone of inhibition ('P' value: 0.0305). Optimal liposomal encapsulated in noticed in 15:10 lecithin: cholesterol concentration (VLP-6). Higher Lecithin and Cholesterol quantity in the liposome formulations resulted in lower drug entrapment efficiency and drug release when compared with middle levels of lecithin and cholesterol content formulation. The pastilles were prepared from the optimized liposomal formulation with a modified method reported in British Pharmaceutical Codex, 1907. These liposomal pastilles were subjected to evaluation of physicochemical parameters, In vitro drug release studies, stability studies, and In vivo bioavailability studies in comparison with pure voriconazole pastilles (PVP). The statistical data analysis results indicated that there was a significant difference in T_max, K_a, t_{1/2 abs}, t_{1/2 elim,} AUC_0-24, AUC_0-∞, AUMC_0-24 and AUMC_0-∞, values among PVP and VLP-6. There was no significant difference in C_max, K_el, MRT_0-24 and MRT_0-∞values among pure voriconazole pastilles and optimized liposomal formulation.

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.

Comparative Evaluation of Etest, EUCAST, and CLSI Methods for Amphotericin B, Voriconazole, and Posaconazole against Clinically Relevant Fusarium Species

We compared EUCAST and CLSI methods versus Etest for antifungal susceptibility testing of 20 clinically relevant Fusarium species against amphotericin B, posaconazole, and voriconazole. The median Etest amphotericin B and posaconazole MICs were 1 dilution higher than the median EUCAST and the CLSI MICs. The essential agreement (within ±1/±2 dilutions) was 60/90%, 80/95%, and 70/85% between the Etest and EUCAST methods and 80/95%, 75/95%, and 45/100% between the Etest and CLSI methods for amphotericin B, voriconazole, and posaconazole, respectively. The categorical agreement was >85%. Etest can be used for antifungal susceptibility testing of Fusarium species.

Fusariosis in a Patient with Acute Myeloid Leukemia: A Case Report and Review of the Literature

Fusarium spp. causes infections mostly in patients with prolonged neutropenia. We describe the case of a disseminated Fusarium solani infection in a patient with acute myeloid leukemia which never reached complete remission during its clinical course. The patient had profound neutropenia and developed skin nodules and pneumonia in spite of posaconazole prophylaxis. F. solani was isolated from blood and skin biopsy, being identified from its morphology and by molecular methods. By broth dilution method, the strain was resistant to azoles, including voriconazole and posaconazole, and to echinocandins. MIC to amphotericin B was 4 mg/L. The patient initially seemed to benefit from therapy with voriconazole and amphotericin B, but, neutropenia perduring, his clinical condition deteriorated with fatal outcome. All efforts should be made to determine the correct diagnosis as soon as possible in a neutropenic patient and to treat this infection in a timely way, assuming pathogen susceptibility while tests of antimicrobial susceptibility are pending. A review of the most recent literature on invasive fungal infections is reported.

Liposomal voriconazole (VOR) formulation for improved ocular delivery

Treating infectious eye diseases topically requires a drug delivery system capable of overcoming the eye's defense mechanisms, which efficiently reduce the drug residence time right after its administration, therefore reducing absorption. In order to try to surpass such administration issues and improve life quality for patients with fungal keratitis, liposomal voriconazol (VOR) formulations were prepared. Formulations were composed of soy phosphatidylcholine (PC) containing or not 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) and cholesterol. Liposomes were characterized by their drug entrapment efficiency (EE), drug recovery (DR), average diameter (size) and polydispersivity index (PdI). In vitro mucosal interaction and irritancy levels, ex vivo permeation, as well as the short-term stability were also assessed. Liposomal VOR formulation produced with 7.2:40mM VOR:PC showed to be the most promising formulation: mean size of 116.6±5.9nm, narrow PdI (0.17±0.06), negative zeta potential (∼-7mV) and over 80% of EE and yield, remaining stable for at least 30 days in solution and 90 days after lyophilization. This formulation was classified as 'non-irritant' after HET-CAM's test and was able to deliver about 47.85±5.72μg/cm(2) of VOR into porcine cornea after 30min of permeation test. Such drug levels are higher than the minimal inhibitory concentrations (MIC) of several fungi species isolated from clinical cases of corneal keratitis. Overall results suggest VOR can be effectively incorporated in liposomes for potential topical treatment of fungal keratitis.

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.

In vitro susceptibility of filamentous fungi from mycotic keratitis to azole drugs

OBJECTIVE

The in vitro antifungal activities of azole drugs viz., itraconazole, voriconazole, ketoconazole, econazole and clotrimazole were investigated in order to evaluate their efficacy against filamentous fungi isolated from mycotic keratitis.

METHODS

The specimen collection was carried out from fungal keratitis patients attending Aravind eye hospital and Post-graduate institute of ophthalmology, Coimbatore, India and was subsequently processed for the isolation of fungi. The dilutions of antifungal drugs were prepared in RPMI 1640 medium. Minimum inhibitory concentrations (MICs) were determined and MIC50 and MIC90 were calculated for each drug tested.

RESULTS

A total of 60 fungal isolates were identified as Fusarium spp. (n=30), non-sporulating moulds (n=9), Aspergillus flavus (n=6), Bipolaris spp. (n=6), Exserohilum spp. (n=4), Curvularia spp. (n=3), Alternaria spp. (n=1) and Exophiala spp. (n=1). The MICs of ketoconazole, clotrimazole, voriconazole, econazole and itraconazole for all the fungal isolates ranged between 16 μg/mL and 0.03 μg/mL, 4 μg/mL and 0.015 μg/mL, 8 μg/mL and 0.015 μg/mL, 8 μg/mL and 0.015 μg/mL and 32 μg/mL and 0.06 μg/mL respectively. From the MIC50 and MIC90 values, it could be deciphered that in the present study, clotrimazole was more active against the test isolates at lower concentrations (0.12-5 μg/mL) when compared to other drugs tested.

CONCLUSION

The results suggest that amongst the tested azole drugs, clotrimazole followed by voriconazole and econazole had lower MICs against moulds isolated from mycotic keratitis.

Use of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of molds of the Fusarium genus

The rates of infection with Fusarium molds are increasing, and a diverse number of Fusarium spp. belonging to different species complexes can cause infection. Conventional species identification in the clinical laboratory is time-consuming and prone to errors. We therefore evaluated whether matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) is a useful alternative. The 289 Fusarium strains from the Belgian Coordinated Collections of Microorganisms (BCCM)/Institute of Hygiene and Epidemiology Mycology (IHEM) culture collection with validated sequence-based identities and comprising 40 species were used in this study. An identification strategy was developed, applying a standardized MALDI-TOF MS assay and an in-house reference spectrum database. In vitro antifungal testing was performed to assess important differences in susceptibility between clinically relevant species/species complexes. We observed that no incorrect species complex identifications were made by MALDI-TOF MS, and 82.8% of the identifications were correct to the species level. This success rate was increased to 91% by lowering the cutoff for identification. Although the identification of the correct species complex member was not always guaranteed, antifungal susceptibility testing showed that discriminating between Fusarium species complexes can be important for treatment but is not necessarily required between members of a species complex. With this perspective, some Fusarium species complexes with closely related members can be considered as a whole, increasing the success rate of correct identifications to 97%. The application of our user-friendly MALDI-TOF MS identification approach resulted in a dramatic improvement in both time and accuracy compared to identification with the conventional method. A proof of principle of our MALDI-TOF MS approach in the clinical setting using recently isolated Fusarium strains demonstrated its validity.

Clinical utility of caspofungin eye drops in fungal keratitis

Treatment of fungal keratitis remains challenging. To date, only the polyenes and azoles are commonly used topically in the management of fungal keratitis. Natamycin, a polyene, is the only antifungal eye drop that is commercially available; the remainder are prepared in-house and are used in an 'off-label' manner. Failure of medical treatment for fungal keratitis is common, hence there is a need for more effective topical antifungal therapy. To increase the antifungal eye drop armamentarium, it is important to investigate the utility of other classes of antifungal agents for topical use. Caspofungin, an echinocandin antifungal agent, could potentially be used to address the existing shortcomings. However, little is known about the usefulness of topically administered caspofungin. This review will briefly explore the incidence, epidemiology and antifungal treatment of fungal keratitis. It will focus primarily on evidence related to the efficacy, safety and practicality of using caspofungin eye drops in fungal keratitis.

[A case of mycotic keratitis due to Fusarium solani in Valdivia, Chile]

BACKGROUND

Keratomycosis is one of the most prevalent ophthalmic infections, which needs a specific treatment depending on the nature of the infecting fungus. The prognosis is usually severe and depends on an early diagnosis and suitable therapy.

CASE REPORT

We describe a case of keratitis due to Fusarium solani in a patient from a rural area, who, between May and October 2011, suffered a corneal trauma caused by dust particles in Valdivia, Chile. On two occasions, direct examination of eye scrapes revealed abundant septate hyphae. All cultures were positive for the same fungus, which was identified as Fusarium solani by phenotypic characterization and sequencing of ribosomal nuclear genes. The patient was initially treated with amphotericin B and afterwards successfully responded to a treatment with oral and intravenous voriconazole, although corneal opacity persisted.

CONCLUSIONS

Although keratomycosis in Chile is rare, its diagnostic particularities must be taken into consideration to establish the most effective treatment. Thus, a rapid visualization of the fungus in the lesion, an efficient isolation of the etiologic agent in pure culture is essential, as well as its rapid identification, which requires the use of molecular sequencing techniques in the case of Fusarium species.

In vitro susceptibility of filamentous fungal isolates from a corneal ulcer clinical trial

PURPOSE

To describe the minimum inhibitory concentration (MIC) of fungal isolates to natamycin and voriconazole, and to compare these MICs to previous ocular susceptibility studies.

DESIGN

Experimental laboratory study using isolates from a randomized clinical trial.

METHODS

The Mycotic Ulcer Treatment Trial I was a randomized, double-masked, multicenter trial comparing topical natamycin and voriconazole for fungal keratitis treatment. Susceptibility testing to natamycin and voriconazole were performed according to Clinical and Laboratory Standards Institute methods. The relationship between organism and MIC was assessed. A literature review was performed to compare results to previous ocular susceptibility studies.

RESULTS

Of the 323 patients enrolled in the trial, MICs were available for 221 (68%). Fusarium (n = 126) and Aspergillus species (n = 52) were the most commonly isolated organisms. MICs to natamycin and voriconazole were significantly different across all genera (P < .001). The MIC median (MIC50) and 90th percentile (MIC90) for natamycin were equal to or higher than voriconazole for all organisms except Curvularia species. Compared to other organisms, Fusarium species isolates had the highest MICs to voriconazole and Aspergillus flavus isolates had the highest MICs to natamycin. Our results were similar to previous reports except that the voriconazole MIC90 against Aspergillus species was 2-fold higher and the natamycin MIC90 against Aspergillus fumigatus was 4-fold higher in our study.

CONCLUSION

In this large susceptibility study, Fusarium isolates were least susceptible to voriconazole and A flavus isolates were least susceptible to natamycin when compared to other filamentous fungi. In the future, susceptibility testing may help guide therapy if performed in a timely manner.

Outbreak of fungal endophthalmitis due to Fusarium oxysporum following cataract surgery

Outbreak of exogenous Fusarium endophthalmitis after cataract surgery was evaluated. Twenty patients developed postoperative endophthalmitis. In 19 eyes, pars plana vitrectomy (PPV) was performed, in 14 cases (74 %) with primary intraocular lens explantation. In one case, the PPV was not performed because of poor general condition of the patient. Symptoms of endophthalmitis (damaged vision, iritis, tyndallization in anterior chamber, hypopyon) occurred at intervals of 16-79 days (mean 31.3 days). Fungal etiology was documented in 12 eyes (60 %). Fusarium oxysporum was evidenced by culture and/or microscopy and confirmed by PCR and sequencing analysis. Eighteen (90 %) patients were treated with oral voriconazole (400 mg/day) for a period of 4-6 weeks. The final visual acuity was 6/15 in 1 case (5 %), 6/60 and worse in 17 eyes (85 %), and in 2 cases (10 %), enucleation had to be performed. Viscoelastic filling material was suggested the most likely source of infection. Endophthalmitis caused by Fusarium spp. are a potentially big threat for patients with serious impact on vision. Successful management of the infection is highly dependent on early diagnosis including species identification and antifungal susceptibility testing, and on aggressive and long-term treatment.

Microscopic evaluation, molecular identification, antifungal susceptibility, and clinical outcomes in fusarium, Aspergillus and, dematiaceous keratitis

Purpose. Fusarium, Aspergillus, and Dematiaceous are the most common fungal species causing keratitis in tropical countries. Herein we report a prospective study on fungal keratitis caused by these three fungal species. Methodology. A prospective investigation was undertaken to evaluate eyes with presumed fungal keratitis. All the fungal isolates (n = 73) obtained from keratitis infections were identified using morphological and microscopic characters. Molecular identification using sequencing of the ITS region and antifungal susceptibility tests using microdilution method were done. The final clinical outcome was evaluated in terms of the time taken for resolution of keratitis and the final visual outcome. The results were analyzed after segregating the cases into three groups, namely, Fusarium, Aspergillus, and Dematiaceous keratitis. Results. Diagnosis of fungal keratitis was established in 73 (35.9%) cases out of 208 cases. The spectra of fungi isolated were Fusarium spp. (26.6%), Aspergillus spp. (21.6%), and Dematiaceous fungi (11.6%). The sequence of the ITS region could identify the Fusarium and Aspergillus species at the species complex level, and the Dematiaceous isolates were accurately identified. Using antifungal agents such as fluconazole, natamycin, amphotericin B, and itraconazole, the minimum inhibitory concentrations (MICs) for Fusarium spp. were >32 μg/mL, 4–8 μg/mL, 0.5–1 μg/mL, and >32 μg/mL, respectively. Antifungal susceptibility data showed that Curvularia spp. was highly resistant to all the antifungal agents. Overall, natamycin and amphotericin B were found to be the most effective antifungal agents. The comparative clinical outcomes in all cases showed that the healing response in terms of visual acuity of the Dematiaceous group was significantly good when compared with the Fusarium and Aspergillus groups (P < 0.05). The time required for healing in the Fusarium group was statistically significantly less when compared with the Aspergillus and Dematiaceous groups. Conclusion. This study demonstrates important differences in microscopic features of scraping material and antifungal susceptibility between the three groups. Early and accurate identification coupled with the MIC data, and thereby appropriate treatment is crucial for complete recovery.

Fusarium keratitis in South India: causative agents, their antifungal susceptibilities and a rapid identification method for the Fusarium solani species complex

Seventy Fusarium isolates derived from human keratomycosis were identified based on partial sequences of the β-tubulin (β-TUB) and translation elongation factor 1α (EF-1α) genes. Most of the isolates were confirmed as members of the F. solani species complex (75.71%), followed by the F. dimerum species complex (8.57%), the F. fujikuroi species complex (8.57%), the F. oxysporum species complex (4.29%) and the F. incarnatum-equiseti species complex (2.86%). A combined phylogenetic tree was estimated including all the 70 isolates. Isolates belonging to different species complexes formed separate clades. In this study, we also report the first isolation of F. napiforme from human keratomycosis. A new method based on a specific EcoRI restriction site in the EF-1α gene was developed for the rapid identification of F. solani. In vitro antifungal susceptibilities of the isolates to seven antifungals were determined by broth microdilution method. Terbinafine, natamycin and amphotericin B proved to be the most effective drugs, followed by voriconazole. The minimal inhibitory concentrations of clotrimazole, econazole and itraconazole were generally high (≥64 μg ml(-1) ). The interactions between the two most effective antifungals (natamycin and terbinafine) were determined by checkerboard microdilution method. Synergism (71.8%) or no interaction (28.2%) was revealed between the two compounds.

Fusarium keratitis: genotyping, in vitro susceptibility and clinical outcomes

PURPOSE

To determine differences in the clinical characteristics and antifungal susceptibility patterns among molecularly characterized ocular Fusarium sp isolates.

METHODS

Fifty-eight isolates of Fusarium sp obtained from 52 eyes of 52 patients were retrieved from the Ocular Microbiology Laboratory of the Bascom Palmer Eye Institute and grown in pure culture. These isolates were characterized based on DNA sequence analysis of the ITS1/2 and ribosomal deoxyribonucleic acid regions. Antifungal susceptibilities were determined for each isolate using broth microdilution methods, and the corresponding medical records were reviewed to determine the clinical outcomes.

RESULTS

Fusarium solani isolates had significantly higher values of minimum inhibitory concentration for 90% isolates (MIC90) with voriconazole than F. non-solani organisms (16 and 4 μg/mL, respectively). Isolates of F. solani also exhibited a significantly longer time to cure (65 vs. 40.5 days), a worse follow-up best-corrected visual acuity (20/118 vs. 20/36), and an increased need for urgent surgical management (7 vs. 0 penetrating keratoplasties) when compared with those of F. non-solani.

CONCLUSIONS

This is the first report to examine the correlation between ocular genotyped Fusarium sp and clinical outcomes. It supports the overall worse prognosis of F. solani versus F. non-solani isolates, including higher voriconazole resistance by the former. The clinical implementation of molecular-based diagnostics and antifungal efficacy testing may yield important prognostic and therapeutic information that could improve the management of fungal ocular infections.

Antifungal effect of ophthalmic preservatives phenylmercuric nitrate and benzalkonium chloride on ocular pathogenic filamentous fungi

In the present study, the antifungal effects of phenylmercuric nitrate and benzalkonium chloride versus those of natamycin and ketoconazole were assessed against 216 filamentous fungi isolates from cases of fungal keratitis. They included 112 Fusarium isolates, 94 Aspergillus isolates, and 10 Alternaria alternata isolates. The strains were tested by broth dilution antifungal susceptibility testing of filamentous fungi approved by the Clinical and Laboratory Standards Institute M38-A document. The results showed that the MIC(50) values of phenylmercuric nitrate were 0.0156, 0.0156, and 0.0313 μg/mL for Fusarium spp., Aspergillus spp., and A. alternata, respectively. The MIC(90) values of phenylmercuric nitrate were 0.0313, 0.0313, and 0.0313 μg/mL for Fusarium spp., Aspergillus spp., and A. alternata, respectively. The MIC(50) values of benzalkonium chloride were 16, 32, and 8 μg/mL for Fusarium spp., Aspergillus spp., and A. alternata, respectively. The MIC(90) values of benzalkonium chloride were 32, 32, and 16 μg/mL for Fusarium spp., Aspergillus spp., and A. alternata, respectively. The study indicates that phenylmercuric nitrate has considerable antifungal activity and its effect is significantly superior to those of benzalkonium chloride, natamycin, and ketoconazole against ocular pathogenic filamentous fungi in vitro, deserving further investigation for treating fungal keratitis as a main drug.

Successful medical management of recalcitrant Fusarium solani keratitis: molecular identification and susceptibility patterns

Fungal keratitis is a rare but sight-threatening infection of the cornea that may be caused by several fungal pathogens. A delay in diagnosis and inadequate treatment may even lead to loss of the affected eye. Fungal keratitis is often misdiagnosed as bacterial keratitis because isolation and identification of the fungal pathogen is difficult and requires experience, and fungal growth in culture requires time. In this report, a 14-year-old boy with recalcitrant Fusarium solani keratitis, unresponsive to initial therapy, is presented. CLSI M38-A2 in vitro antifungal susceptibility tests demonstrated that only amphotericin B (0.5 μg/ml) had potent activity against F. solani; however, fluconazole (>64 μg/ml), itraconazole (>16 μg/ml), voriconazole (8 μg/ml), and posaconazole (>16 μg/ml) had high minimum inhibitory concentrations. In addition, caspofungin (>16 μg/ml) and anidulafungin (>16 μg/ml) exhibited high minimum effective concentrations. Repeated intrastromal voriconazole injections, topical voriconazole, and caspofungin combined with systemic antifungal agents improved of the corneal lesion with a significant increase in visual acuity. Intrastromal voriconazole injection may be used as an adjunctive treatment method for recalcitrant fungal keratitis with no prominent complications. The intrastromal route could be an effective route of administration of antifungal agents, especially for F. solani keratitis, as in this case. A combination of various antifungal agents administered by different routes prevented loss of the eye.

Epidemiologic cutoff values for triazole drugs in Cryptococcus gattii: correlation of molecular type and in vitro susceptibility

Cryptococcus gattii causes infection in tropical and subtropical regions worldwide but has garnered increased attention since its 1999 emergence in North America. C. gattii can be divided into 4 molecular types that may represent cryptic species. Recent evidence has shown that azole antifungal MIC values differ among these molecular types. We tested a large collection of C. gattii isolates for susceptibility to 4 azole drugs. We found that isolates of molecular type VGII have the highest geometric mean (GM) fluconazole MIC values (8.6 μg/mL), while isolates of molecular type VGI have the lowest (1.7 μg/mL). For fluconazole, itraconazole, and voriconazole GM MIC values, VGI < VGIII < VGIV < VGII. The GM MIC values for posaconazole were similarly represented across molecular types, with the exception that VGII < VGIII and VGIV. We used the MIC values to establish preliminary epidemiologic cutoff values for each azole and molecular type of C. gattii.

International retrospective analysis of 73 cases of invasive fusariosis treated with voriconazole

The outcomes for 73 invasive fusariosis patients treated with voriconazole were investigated. Patients with proven (n = 67) or probable (n = 6) infections were identified from the voriconazole clinical database (n = 39) and the French National Reference Center for Mycoses and Antifungals database (n = 34). Investigator-determined success was a complete or partial response. Survival was determined from day 1 of voriconazole therapy to the last day known alive. Patients were 2 to 79 years old (median, 43 years), and 66% were male. Identified Fusarium species (62%) were F. solani, F. moniliforme, F. proliferatum, and F. oxysporum. Underlying conditions analyzed included hematopoietic stem cell transplant (HSCT; 18%), hematologic malignancy (HM; 60%), chronic immunosuppression (CI; 12%), or other condition (OC; 10%). Infection sites were brain (5%), disseminated excluding brain (67%), lungs/sinus (15%), and other (12%). Most patients (64%) were or had recently been neutropenic (<500 cells/mm(3)). Therapy duration was 1 to 480 days (median, 57 days), with a 47% success rate. Baseline neutropenia impacted success adversely (P ≤ 0.03). Success varied by underlying condition (HSCT, 38%; HM, 45%; CI, 44%; OC, 71%) and infection site (brain, 0%; disseminated, 45%; other, 56%; lung/sinus, 64%) (P > 0.05). Combination therapy (13 patients) was no better than treatment with voriconazole alone. Overall, 59% of the patients died (49% died of fusariosis), and 90-day survival was 42%. Site of infection influenced survival (P = 0.02). Median survival (in days) by species was as follows: F. solani, 213; F. oxysporum, 112; Fusarium spp., 101; F. proliferatum, 84; F. moniliforme, 76. We conclude that voriconazole is a therapeutic option for invasive fusariosis.

New triazoles and echinocandins: mode of action, in vitro activity and mechanisms of resistance

Different types of mycoses, especially invasive mycoses caused by yeasts and molds, are a growing problem in healthcare. The most notable explanation for this increase is a rise in the number of immunocompromised patients owing to advances in transplantation, the emergence of AIDS and a rise in the number of invasive surgical procedures. Despite advances in medical practice, some therapeutic problems remain. In addition, intrinsic or acquired antifungal resistance may pose a serious problem to antifungal therapy. A new generation of triazole agents (voriconazole, posaconazole, isavuconazole, ravuconazole and albaconazole) and the recent class of the echinocandins (caspofungin, micafungin and anidulafungin) have become available, and represent an alternative to conventional antifungals for serious fungal infection management. Currently, only two of the recent triazole generation (voriconazole and posaconazole) and all three echinocandins are available for clinical use. More precisely, voriconazole and posaconazole are indicated for the treatment of invasive fungal infections and the echinocandins for the treatment of specific candidiasis. Voriconazole and posaconazole have a very broad spectrum of antifungal activity that includes Candida species, and filamentous and dimorphic fungi. Their activity extends to both fluconazole- and itraconazole-resistant strains of Candida. A major difference between posaconazole and voriconazole is that posaconazole has activity against Zygomycetes including Mucor spp., Rhizopus spp. and Cunninghamella spp., and voriconazole has no activity against this class of fungi. Ravuconazole, isavuconazole and albaconazole have shown very potent in vitro activity against species of Candida, Cryptococcus and Aspergillus, and they are currently in various stages of development. All three echinocandin agents, caspofungin, micafungin and anidulafungin, are similar in their spectrum of activity. Echinocandins do not possess in vitro activity against important basidiomycetes, including Cryptococcus, Rhodotorula and Trichosporon. This review attempts to deliver the most up-to-date knowledge on the mode of action and mechanisms of resistance to triazoles and echinocandins in fungal pathogens. In addition, the in vitro activity data available on triazoles and echinocandins are reported.

Pathogenesis and outcome of Paecilomyces keratitis

PURPOSE

To examine the clinical pathology and management of Paecilomyces lilacinus keratitis.

DESIGN

Observational case series, literature review, and laboratory study.

METHODS

Characteristics and outcome of 17 patients with laboratory-confirmed Paecilomyces keratitis treated at 2 referral centers were combined with 25 previously reported cases. Experimental models were developed by topically inoculating a human corneal isolate of P. lilacinus onto murine eyes and onto human donor corneas.

RESULTS

Of 42 reported eyes with Paecilomyces keratitis, 13 (31%) were associated with chronic keratopathy or previous ocular surgery, 11 (26%) followed corneal trauma, and 10 (24%) occurred in soft contact lens wearers. Medical cure occurred in 13 (31%), including 9 of 31 eyes (29%) treated with natamycin or amphotericin B. Penetrating keratoplasty or other surgery was performed in 29 (69%). In vitro testing of P. lilacinus indicated resistance to natamycin and amphotericin B but susceptibility to ketoconazole and voriconazole. Experimental inoculation after superficial scarification established moderately severe corneal paecilomycosis by hyphae and conidia in immunosuppressed mice and in explanted donor corneas.

CONCLUSIONS

P. lilacinus is an emerging fungal pathogen that infects corneal tissue by filamentous invasion with occasional intrastromal sporulation. P. lilacinus keratitis does not reliably respond to natamycin or amphotericin B and has often required therapeutic keratoplasty, but topical azole antifungal agents such as voriconazole appear promising.