Pharmacotherapy of fungal eye infections

Toxicity of simultaneous intrastromal and intracameral injection of voriconazole on corneal endothelium in a rabbit model

PURPOSE

To investigate the toxicity of repeated simultaneous intrastromal and intracameral injections of voriconazole in corneal endothelial cells in a rabbit model.

METHODS

Thirty-six eyes of 18 New Zealand white rabbits (six eyes per group) were divided into 6 groups according to the concentration of voriconazole (Group A, 0%; Group B, 0.05%; Group C, 0.1%; Group D, 0.25%; Group E, 0.5%; Group F, 1%). A combination of intrastromal and intracameral voriconazole injections were administrated to the eyes of each group three times on days 0, 3, and 7. Corneal clouding grades and central corneal thickness (CCT) were examined on days 0, 3, 7, 10, and 14. The endothelial cell counts (ECC) were measured on days 0 and 14. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed on day 14.

RESULTS

Group F (1%) showed more severe corneal clouding than the other groups (Groups A-E) from day 7 (p < 0.05, respectively). There were no significant differences in CCT and ECC among the six groups at any time point (p > 0.05, respectively). SEM revealed blurring of the cell border and loss of microvilli at concentrations ≥0.25% (Groups D-F). TEM revealed microstructural changes in endothelial cells at concentrations ≥0.1% (Groups C-F), and multiple vacuoles were observed at a concentration of 1% voriconazole (Group F).

CONCLUSIONS

Repeated simultaneous intrastromal and intracameral voriconazole injections at a concentration of 0.1% or higher induced microstructural endothelial damage in rabbit corneal endothelial cells.

Fungal keratitis caused by Scedosporium apiospermum: a case report

Background

We present a case of fungal keratitis caused by Scedosporium apiospermum, which is a rare agent.

Case description

A 34-year-old Caucasian male patient was admitted to our clinic with complaints of pain and blurred vision in the left eye. The patient had a history of wearing contact lenses for 3 years. According to the Snellen chart, the patient’s visual acuity was 20/20 and counting fingers at 30 cm, for right and left eyes, respectively. A 3 × 3 mm corneal abscess at the center of the cornea with hypopyon in the patient’s left eye was observed. After the patient was hospitalized, fortified gentamicin and fortified cefazolin drops were started 24 times per day. Intravenous fluconazole 1 × 800 mg loading, 1 × 400 mg maintenance dose, intravenous vancomycin 4 × 500 mg and intravenous cefoperazone + sulbactam 2 × 2 g treatments were started. We observed S. apiospermum in the corneal scraping sample, which the identification was performed by combined phenotypic characteristics and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry on the sixth day of treatment. The drops were revised as fortified vancomycin, ceftazidime, and voriconazole drops 24 times per day. Intravenous voriconazole 2 × 6 mg/kg loading and 2 × 4 mg/kg maintenance dose treatments were started. Three weeks later, left eye visual acuity increased to 20/40, and the corneal abscess regressed. On second-year follow-up, his visual acuity increased to 20/25 for the left eye and the cornea was transparent.

Conclusion

Scedosporium group is an opportunistic filamentous fungus that is very rarely seen and causes severe keratitis infections. In the literature, to the best of our knowledge, three cases of keratitis due to S. apiospermum after contact lenses were reported, and all were treated with penetrating keratoplasty. In this case, unlike the others, only medical treatment was applied. In cases with suspected fungal keratitis, medical treatment should be started without waiting for the culture result, the findings should be followed and penetrating keratoplasty should be performed in the case of no response to treatment.

Implementation of HILIC-UV technique for the determination of moxifloxacin and fluconazole in raw materials and pharmaceutical eye gel

Hydrophilic interaction liquid chromatography (HILIC) has inherent merits over RP-HPLC in the analyzing of hydrophilic substances. Accordingly, an innovative HILIC-UV methodology is proposed for the simultaneous estimation of ethyl paraben (PRN), fluconazole (FLZ) and moxifloxacin hydrochloride (MOX) in raw materials and pharmaceutical eye gel. The separation process was conducted using Waters XBridge™ HILIC column (100 mm × 4.6 mm, 3.5 μm particle size) at room temperature. Isocratic mobile phase containing acetonitrile: 0.1% triethylamine buffer (90:10, v/v, pH 5.0), was pumped at flow rate 1.0 mL/min and detected at 260 nm. Under these optimized conditions, PRN, FLZ and MOX showed rectilinear relationships with the concentration ranges (0.5–6.0), (5.0–50.0) and (5.0–60.0) μg/mL, respectively. The developed method offered at least fivefold increase in sensitivity within shorter time than the reported methods. Three greenness assessment tools namely: Analytical eco-scale, GAPI and AGREE were exploited to investigate the method's impact on the environment and conduct a comparative study with the reported methods. International council of Harmonization (ICH) guidelines have been followed to calculate validation parameters. The statistical comparison between results of the suggested method and the comparison method showed no discrepancy confirming accuracy of the method.

Successful treatment of Candida albicans anterior chamber infection after penetrating keratoplasty

Purpose

To report the successful management of an anterior chamber (AC) infection after penetrating keratoplasty (PK) caused by Candida albicans.

Observation

A 53-year-old female had a PK in her right eye. The donor rim tested positive for Candida albicans one week later. Despite initiation of prophylactic topical 1% voriconazole drops, the patient presented with a white mass in the anterior chamber one month later. Biopsy confirmed Candida. Antifungal therapy was intensified with the addition of intravenous fluconazole, and with repeated irrigations of the AC and intracameral administration of amphotericin B (off-label use). After two weeks of apparent lack of treatment response, the infection suddenly quiesced. The final outcome was visual acuity of 0.2 and a clear graft with an endothelial cell density of 2260 cells/mm. ²

Conclusions and Importance

Fungal intraocular infections after PK are usually devastating. Due to low intraocular penetration of topical antifungals, serial intracameral injections were used to maintain a therapeutic concentration of amphotericin B within the anterior chamber, and intravenous fluconazole was administered to protect against the spread of infection into the vitreous. A clinical response developed after two weeks. The reported case represents a favorable outcome using a multimodal approach.

Efficacy of Voriconazole Corneal Intrastromal Injection for the Treatment of Fungal Keratitis

Purpose

To evaluate efficacy and safety of novel tricyclic corneal stroma injection (TCSI) voriconazole for the treatment of fungal keratitis.

Methods

This retrospective cohort study included data of 57 patients (57 eyes) with fungal keratitis. The TCSI group consisted of 27 patients (27 eyes) who were injected voriconazole once via TCSI procedure within one week after enrollment, in addition to conventional antifungal treatment. The control group consisted of 30 patients (30 eyes) who were treated using conventional antifungal treatment modalities. The outcome measures consist of the 3-week and 3-month best-corrected visual acuity (BCVA) values and size of infiltrate or scar, time to re-epithelialization, corneal perforation rate and/or therapeutic penetrating keratoplasty (TPK) requirement, the preoperative and post-TCSI corneal endothelial cell density (ECD), and the intraocular pressure (IOP) of the treated eye and the respective contralateral eye.

Results

There were no significant differences in the baseline demographic and clinical characteristics between the two groups. 3 weeks and 3 months after enrollment, the TCSI group exhibited an increase in visual acuity (P < 0.05), and there was no significant difference in the size of infiltrate or scar between two groups (P > 0.05). Time to re-epithelialization was shorter in the TCSI group than in the control group (P < 0.05). There was no statistically significant difference between corneal ECD on the day before and 7 days after TCSI and the IOP of treated and contralateral healthy eyes on the day before and 1 day, 3 days, 7 days, and 1 month after TCSI (P > 0.05). The difference in the risk of perforation and/or TPK requirement was not statistically significant between two groups (P > 0.05).

Conclusion

Localized injection of voriconazole using TCSI may be a minimally invasive, safe, and effective adjuvant treatment modality for fungal keratitis.

In situ forming and mucoadhesive ophthalmic voriconazole/HPβCD hydrogels for the treatment of fungal keratitis

Fungal keratitis is a severe infectious corneal disease. At present, no voriconazole ophthalmic formulations are approved by the FDA or EMA. This lack of therapeutic options leads to the reformulation of intravenous voriconazole preparations (VFEND®) by the hospital pharmacy departments to prepare the appropriate ophthalmic formulations (pharmacy compounding). However, the limited residence time of these formulations leads to an intensive treatment posology that may increase the occurrence of side effects. In the present study, two different hydrogels were developed and characterized in order to improve the voriconazole's ophthalmic solubility, permanence, and security. Voriconazole-cyclodextrin (HPβCD or HPɣCD) inclusion complexes in aqueous solutions were characterized by NMR and molecular modeling. Complexes were formed by encapsulation of voriconazole into the cyclodextrin's internal cavity which considerably increases its water solubility. Ocular safety was proven by ocular irritation studies. Permeability studies suggest both hydrogels have good corneal permeability. Furthermore, in vivo ocular permanence study by PET/CT showed a longer permanence time on the ocular surface (t_1/2 = 58.91 ± 13.4 min and 96.28 ± 49.11 min for VZHAH and VZISH 0.65 respectively) compared to the voriconazole control formulation (VFEND® t_1/2 = 32.27 ± 15.56 min). Results suggest these formulations are a good alternative for the treatment of fungal keratitis.

Lenticular fungal infection caused by Aspergillus in a patient with traumatic corneal laceration: a case report

Background

To report a case of lenticular infection caused by Aspergillus, which was diagnosed 13 weeks after traumatic corneal laceration.

Case presentation

A 60-year-old woman presented with traumatic corneal laceration including anterior lens capsule rupture and traumatic cataract after being hit with a chestnut in the right eye. There were multiple injuries due to tiny thorns of the chestnut, including the conjunctiva, sclera, cornea, and anterior lens capsule. But no visible foreign body was detected by slit-lamp examination. Topical corticosteroid was prescribed to resolve the conjunctival inflammation induced by the thorns of chestnut, which could have caused persistent irritation. As conjunctival injection and edema being decreased during outpatient clinical follow-up, embedded conjunctival foreign body was detected and surgically removed (1st surgery). Approximately 10 weeks after the trauma, severe inflammation of the anterior segment accompanied with hypopyon developed suddenly and at the same time embedded scleral foreign body was revealed. After removal of scleral foreign body (2nd surgery), unspecified mold species was cultured from the scleral foreign body in SDA (Sabouraud dextrose agar) plate. Suspicious corneal foreign body was removed as 3rd surgery and phacoemulsification of traumatic cataract was planned as 4th surgery. Aspergillus was finally detected from removed anterior capsule and fibrotic membrane during the operation. Fungal infection resolved successfully after administration of topical (1% voriconazole and 5% natamycin) and systemic (fluconazole) antifungal agents and phacoemulsification of traumatic cataract.

Conclusion

Chestnut thorns can damage multiple ocular tissues simultaneously. Lens capsular rupture could result in fungal inoculation and lead to delayed lenticular fungal infection with complicated cataract formation. In cases of ocular trauma due to organic substances such as thorns and branches, the possibility of fungal infection should be considered.

A stepwise optimization strategy to formulate in situ gelling formulations comprising fluconazole-hydroxypropyl-beta-cyclodextrin complex loaded niosomal vesicles and Eudragit nanoparticles for enhanced antifungal activity and prolonged ocular delivery

Fungal keratitis and endopthalmitis are serious eye diseases. Fluconazole (FL) is indicated for their treatment, but suffers from poor topical ocular availability. This study was intended to improve and prolong its ocular availability. FL niosomal vesicles were prepared using span 60. Also, polymeric nanoparticles were prepared using cationic Eudragit RS100 and Eudragit RL100. The investigated particles had adequate entrapment efficiency (EE%), nanoscale particle size and high zeta potential. Subsequently, formulations were optimized using full factorial design. FL-HP-β-CD complex was encapsulated in selected Eudragit nanoprticles (FL-CD-ERS1) and niosmal vesicles. The niosomes were further coated with cationic and bioadhesive chitosan (FL-CD-Nios-ch). EE% for FL-CD-ERS1 and FL-CD-Nios-ch formulations were 76.4% and 61.7%; particle sizes were 151.1 and 392 nm; also, they exhibited satisfactory zeta potential +40.1 and +28.5 mV. In situ gels were prepared by poloxamer P407, HPMC and chitosan and evaluated for gelling capacity, rheological behavior and gelling temperature. To increase the precorneal residence time, free drug and selected nano-formulations were incorporated in the selected in situ gel. Release study revealed sustained release within 24 h. Permeation through excised rabbits corneas demonstrated enhanced drug flux and large AUC_0-6h in comparison to plain drug. Corneal permeation of selected formulations labeled with Rhodamine B was visualized by Confocal laser microscopy. Histopathological study and in vivo tolerance test evidenced safety. In vivo susceptibility test using Candida albicans depicted enhanced growth inhibition and sustained effect. In this study the adopted stepwise optimization strategy combined cylodextrin complexation, drug nano-encapsulation and loading within thermosenstive in situ gel. Finally, the developed innovated formulations displayed boosted corneal permeation, enhanced antifungal activity and prolonged action.

Comparison of intravitreal antifungal 100 μg voriconazole and 5 μg amphotericin B in experimental <em>Aspergillus flavus</em> endophthalmitis model in rabbits

BACKGROUND Fungal endophthalmitis is a sight-threatening disease associated with high morbidity and Aspergillus sp. is the most common causes. Voriconazole (VCZ) and Amphotericin B (AmB) are the most used antifungal drugs, while head-to-head comparison for in vivo intravitreal efficacy is still unknown. This study was aimed to compare the efficacy of both agents against Aspergillus flavus.  METHODS A randomized, masked, controlled-experimental study was conducted on 15 albino New Zealand white rabbits. Endophthalmitis was induced by intravitreal inoculation of Aspergillus flavus. Intravitreal injection was given 24 hours post-inoculation, the rabbits were divided into three groups; 100 μg/0.1 ml VCZ intravitreal injection, 5 μg/0.1 ml AmB, and control. Clinical evaluation of corneal opacity, aqueous cells and flare, and vitreous opacity using Yang’s method of quantification were performed at day 1, 3, 5, 7, and 10 after treatment. Mycology quantitative analysis and histopathological examination were performed at the final evaluation.  RESULTS Clinical evaluation showed improvement of inflammation in the VCZ and AmB treatment groups (Δ score −2.1 [2.8] and −1.0 [3.2]) compared with the control group (Δ score 0.8 [3.1]). Although the VCZ group demonstrated a better clinical response with less inflammation and relatively intact retina structures in the histopathology result. Number of fungal colony was significantly less in AmB group (CFU/0.1 ml, p < 0.05).  CONCLUSIONS Favorable clinical improvement was shown in VCZ group compared to AmB group. Intravitreal VCZ showed a better clinical response tendency for Aspergillus flavus-induced endophthalmitis in rabbits.

Designing and enhancing the antifungal activity of corneal specific cell penetrating peptide using gelatin hydrogel delivery system

Background

Fungal keratitis is a major cause of corneal blindness accounting for more than one-third of microbiologically proven cases. The management of fungal keratitis is through topical or systemic antifungal medications alone or in combination with surgical treatment. Topical medications such as natamycin and voriconazole pose major challenges due to poor penetration across the corneal epithelium. To address the issue various carrier molecules like nanoparticles, lipid vesicles, and cell penetrating peptides were explored. But the major drawback such as non-specificity and lack of bioavailability remains.

Purpose

In this study, we have attempted to design corneal specific cell penetrating peptide using subtractive proteomic approach from the published literature and tried to improve its bioavailability through gelatin hydrogel delivery system.

Material and Methods

Using subtractive proteomic approach two peptides VRF005 and VRF007 were identified on the basis of solubility, cell permeability and amphipathicity. The peptides were modeled for three-dimensional structure and simulated for membrane penetration. The peptides were characterized using circular dichroism spectroscopy, dynamic light scattering and native polyacrylamide gel electrophoresis. Further uptake studies were performed on primary corneal epithelial cells and the stability was analyzed in corneal epithelial tissue lysates. Insilico prediction of peptides showed it to have antifungal activity which was further validated using colony forming assay and time killing kinetics. The duration of antifungal activity of peptide was improved using gelatin hydrogel through sustained delivery.

Results

VRF005 and VRF007 showed α-helical structure and was within the allowed region of Ramachandran plot. The simulation study showed their membrane penetration. The peptide uptake was found to be specific to corneal epithelial cells and also showed intracellular localization in Candida albicans and Fusarium solani. Peptides were found to be stable up to 2 hours when incubated with corneal epithelial tissue lysate. Dynamic light scattering, and native polyacrylamide gel electrophoresis revealed aggregation of peptides. VRF007 showed antifungal activity up to 24 hour whereas VRF005 showed activity up to 4 hours. Hence gelatin hydrogel-based delivery system was used to improve the activity. Actin staining of corneal epithelial cells showed that the cells were attached on gelatin hydrogel.

Conclusion

We have designed corneal specific cell penetrating peptides using subtractive proteomic approach. Bioavailability and delivery of peptide was enhanced using gelatin hydrogel system.

Lipid nanoparticles (SLN, NLC): Overcoming the anatomical and physiological barriers of the eye - Part II - Ocular drug-loaded lipid nanoparticles

In the recent decades, various controlled delivery systems have been introduced with the aim to improve solubility, stability and bioavailability of poorly absorbed drugs. Among all, lipid nanoparticles gather interesting properties as drug or gene delivery carriers. These systems, composed either of solid lipids (SLN) or of solid and liquid lipids (NLC) stabilized with surfactants, combine the advantages of other colloidal particles such as polymeric nanoparticles, fat emulsions and liposomes avoiding their main disadvantages. Lipid nanoparticles represent an interesting approach for eye drug delivery as they can improve the corneal absorption of drugs enhancing their bioavailability. The Generally Recognized as Safe status of formulation excipients, the scaling-up facilities and the possibility of sterilization, make them suitable for industrial production. In this review, the latest findings, potential applications, and challenges related to the use of lipid nanoparticles for ocular drug delivery are comprehensively discussed.

Bacterial and fungal keratitis in Upper Egypt: in vitro screening of enzymes, toxins and antifungal activity

Purpose:

This work was conducted to study the ability of bacterial and fungal isolates from keratitis cases in Upper Egypt to produce enzymes, toxins, and to test the isolated fungal species sensitivity to some therapeutic agents.

Materials and Methods:

One hundred and fifteen patients clinically diagnosed to have microbial keratitis were investigated. From these cases, 37 bacterial isolates and 25 fungal isolates were screened for their ability to produce extra-cellular enzymes in solid media. In addition, the ability of fungal isolates to produce mycotoxins and their sensitivity to 4 antifungal agents were tested.

Results:

Protease, lipase, hemolysins, urease, phosphatase, and catalase were detected respectively in 48.65%, 37.84%, 59.46%, 43.24%, 67.57%, and 100% out of 37 bacterial isolates tested. Out of 25 fungal isolates tested during the present study, 80% were positive for protease, 84% for lipase and urease, 28% for blood hemolysis, and 100% for phosphatase and catalase enzymes. Thirteen fungal isolates were able to produce detectable amounts of 7 mycotoxins in culture medium (aflatoxins (B1, B2, G1, and G2), sterigmatocystin, fumagillin, diacetoxyscirpenol, zearalenone, T-2 toxin, and trichodermin). Among the antifungal agents tested in this study, terbinafine showed the highest effect against most isolates in vitro.

Conclusion:

In conclusion, the ability of bacterial and fungal isolates to produce extracellular enzymes and toxins may be aid in the invasion and destruction of eye tissues, which, in turn, lead to vision loss.

Effects of Lamellar Keratectomy and Intrastromal Injection of 0.2% Fluconazole on Fungal Keratitis

Purpose. To evaluate effects of lamellar keratectomy and intrastromal injection of 0.2% fluconazole (LKIIF) on fungal keratitis. Methods. Data for 54 eyes of consecutive patients with fungal keratitis treated with LKIIF were retrospectively analyzed. The lesions in these eyes did not heal or were aggravated after antifungal chemotherapy for 7 days. The maximum lesion diameters were ≤5 mm and maximum depth was not more than half of full corneal thickness. Cases were followed up for at least 90 days. Results. Forty-six eyes were cured (85.2%). The wound healing times were 3–16 days and were less than 7 days in 28 cases (51.9%). In cured eyes, uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) were both 20/250–20/20. The UCVA improved in 38 eyes and was unchanged in seven eyes. BCVA improved in 44 eyes and was unchanged in two eyes. When followed up for more than 90 days, 89% (41 of 46 eyes) showed improvement in UCVA and 11% were unchanged. Regarding BCVA, 98% improved and one eye was unchanged. No other complications were observed except neovascularization in one eye and thinner corneas. Conclusions. LKIIF was quick and effective for small fungal keratitis confined to half of the corneal thickness.

Exogenous fungal endophthalmitis: an analysis of isolates and susceptibilities to antifungal agents over a 20-year period (1990-2010)

PURPOSE

To describe the isolates and susceptibilities to antifungal agents for patients with culture-proven exogenous fungal endophthalmitis.

DESIGN

Noncomparative case series.

METHODS

The clinical records of all patients treated for culture-proven exogenous fungal endophthalmitis at a university referral center from 1990 to 2010 were reviewed. Specimens initially used for diagnosis were recovered from the microbiology department and then underwent antifungal sensitivity analysis.

RESULTS

The antifungal susceptibilities of 47 fungal isolates from culture-positive fungal endophthalmitis are reported. Included are 14 isolates from yeast and 33 from mold. The mean (±standard deviation) minimum inhibitory concetrations (MICs) for amphotericin B (2.6 ± 3.5 μg/mL), fluconazole (36.9 ± 30.7 μg/mL), and voriconazole (1.9 ± 2.9 μg/mL) are reported. Presumed susceptibility to oral fluconazole, intravenous amphotericin B, intravitreal amphotericin B, oral voriconazole, and intravitreal voriconazole occurred in 34.8%-43.5%, 0-8.3%, 68.8%, 69.8%, and 100% of isolates, respectively.

CONCLUSIONS

Based on this laboratory study of isolates from exogenous fungal endophthalmitis, intravitreal voriconazole appears to provide the broadest spectrum of antifungal coverage and, as such, may be considered for empiric therapy of endophthalmitis caused by yeast or mold.

Design and Evaluation of Voriconazole Eye Drops for the Treatment of Fungal Keratitis

Voriconazole is a novel antifungal agent with excellent broad spectrum activity commercially available for oral and intravenous administration. The purpose of this study was to prepare ophthalmic formulation of hydroxypropyl beta cyclodextrin (HP-β-CD) based voriconazole containing benzalkonium chloride BAK and EDTA with or without viscosity modifiers and study its permeation characteristics through freshly excised goat cornea. The results were observed that viscosity and force of bioadhesion of the voriconazole HP-β-CD solutions containing xanthan gum (XG) are more as compared to polyvinyl alcohol. The results revealed that voriconazole drop containing PVA provided least viscosity and higher corneal permeation of drug, while drop formulated with XG had maximum viscosity and least permeation. The HP-β-CD based voriconazole (1.5%) ophthalmic formulation containing xanthan gum (1.5), preserved with BAK and EDTA, could provide shelf life of 2 years. The microbiological studies showed that voriconazole ophthalmic solution containing xanthan gum shows better antifungal activity as compared to voriconazole and xanthan gum alone. Thus, it can be concluded that HP-β-CD based voriconazole (1.5%, pH 7.0) ophthalmic solution containing BAK and EDTA with viscosity modifier XG provided maximum precorneal residence time as compared to other viscosity modifiers and polyvinyl alcohol provided less precorneal residence time than other viscosity modifiers.

[Recommendations for the management of candidemia in adults in Latin America. Grupo Proyecto Épico]

Candidemia is one of the most frequent opportunistic mycoses worldwide. Limited epidemiological studies in Latin America indicate that incidence rates are higher in this region than in the Northern Hemisphere. Diagnosis is often made late in the infection, affecting the initiation of antifungal therapy. A more scientific approach, based on specific parameters, for diagnosis and management of candidemia in Latin America is warranted. 'Recommendations for the diagnosis and management of candidemia' are a series of manuscripts that have been developed by members of the Latin America Invasive Mycosis Network. They aim to provide a set of best-evidence recommendations for the diagnosis and management of candidemia. This publication, 'Recommendations for the management of candidemia in adults in Latin America', was written to provide guidance to healthcare professionals on the management of adults who have, or who are at risk of, candidemia. Computerized searches of existing literature were performed by PubMed. The data were extensively reviewed and analyzed by members of the group. The group also met on two occasions to pose questions, discuss conflicting views, and deliberate on a series of management recommendations. 'Recommendations for the management of candidemia in adults in Latin America' includes prophylaxis, empirical therapy, therapy for proven candidemia, patient work-up following diagnosis of candidemia, duration of candidemia treatment, and central venous catheter management in patients with candidemia. This manuscript is the second of this series that deals with diagnosis and treatment of invasive candidiasis. Other publications in this series include: 'Recommendations for the diagnosis of candidemia in Latin America', 'Recommendations for the management of candidemia in children in Latin America', and 'Recommendations for the management of candidemia in neonates in Latin America'.

Analysis of current antifungal agents and their targets within the Pneumocystis carinii genome

Pneumocystis pneumonia (PCP) remains a leading opportunistic infection in patients with weakened immune systems. The fungus causing the infection belongs to the genus, Pneumocystis, and its members are found in a large variety of mammals. Adaptation to the lung environment of a host with an intact immune system has been a key to its successful survival. Unfortunately, the metabolic strategies used by these fungi to grow and survive in this context are largely unknown. There were considerable impediments to standard approaches for investigation of this unique pathogen, the most problematic being the lack of a long term in vitro culture system. The absence of an ex vivo cultivation method remains today, and many fundamental scientific questions about the basic biology, metabolism, and life cycle of Pneumocystis are unanswered. Recent progress in sequencing of the Pneumocystis carinii genome, a species infecting rats, permitted a more informative search for genes and biological pathways within this pathogen that are known to be targets for existing antifungal agents. In this work, we review the classes of antifungal drugs with respect to their potential applicability to the treatment of PCP. Classes covered in the review are the azoles, polyenes, allylamines, and echinocandins. Factors limiting the use of standard antifungal treatments and the currently available alternatives (trimethoprim-sulfamethoxazole, atovaquone, and pentamidine) are discussed. A summary of genomic sequences within Pneumocystis carinii associated with the corresponding targeted biological pathways is provided. All sequences are available via the Pneumocystis Genome Project at http://pgp.cchmc.org/.

Dendrimer nanoparticles for ocular drug delivery

Eye is a unique organ of perfection and complexity, and is a microcosm of the body in many ways. It represents a great opportunity for nanomedicine, since it is readily accessible-allowing for direct drug/gene delivery to maximize the therapeutic effect and minimize side effects. The development of appropriate delivery systems that can sustain and deliver therapeutics to the target tissues is a key challenge that can be addressed by nanotechnology. Dendrimers are tree-like, nanostructured polymers that have received significant attention as ocular drug delivery systems, due to their well-defined size, tailorable structure, and potentially favorable ocular biodistribution. In this review, we highlight recent developments in dendrimer-based ocular therapies for both anterior and posterior segment diseases.

Vitreous and aqueous penetration of intravitreally and orally administered moxifloxacin in an experimental rabbit model of fungal endophthalmitis

OBJECTIVES

Moxifloxacin (MXF), is a fluoroquinolone drug thought to have some antifungal activity against Candida albicans. The aim of our study was to investigate whether intravitreally and orally administered MXF has an effective penetration into the aqueous and vitreous in an experimental model of C. albicans endophthalmitis.

METHODS

Thirty-two New Zealand rabbits were included. Endophthalmitis was induced in the right eyes of the rabbits. Left eyes were used as sham controls. Group 1 received a single dose of 160 μg MXF/0.1 ml intravitreally. Group 2 received a single intravitreal dose of 160 μg MXF/0.1 ml and an oral dose of 7 mg/kg/day for 4 days. Group 3 received only an oral dose of MXF 7 mg/kg/day for 4 days. Group 4 comprised of healthy controls. On the first and fourth day of treatment aqueous and vitreous samples were aspirated to compare the penetration of MXF.

KEY FINDINGS

Between the first and fourth days, in group 1, mean MXF levels in the aqueous and vitreous tended to decrease; however, in group 3, these drug levels were tended to increase. There was also a decline in the drug levels in the aqueous and vitreous of group 2.

CONCLUSIONS

MXF cannot achieve sufficient penetration into the aqueous and vitreous of eyes infected with C. albicans.

Diversity of microbial species implicated in keratitis: a review

Background:

Microbial keratitis is an infectious disease of the cornea characterised by inflammation and is considered an ophthalmic emergency requiring immediate attention. While a variety of pathogenic microbes associated with microbial keratitis have been identified, a comprehensive review identifying the diversity of species has not been completed.

Methods:

A search of peer-reviewed publications including case reports and research articles reporting microorganims implicated in keratitis was conducted. Search engines including PubMed, Scopus and Web of Science with years ranging from 1950-2012 were used.

Results:

232 different species from 142 genera, representing 80 families were found to be implicated in microbial keratitis. Fungi exhibited the largest diversity with 144 species from 92 genera. In comparison, 77 species of bacteria from 42 genera, 12 species of protozoa from 4 genera and 4 types of virus were identified as the infectious agents. A comparison of their aetiologies shows reports of similarities between genera.

Conclusions:

The diversity of microbial species implicated in keratitis has not previously been reported and is considerably greater than suggested by incidence studies. Effective treatment is heavily reliant upon correct identification of the responsible microorganisms. Species identification, the risk factors associated with, and pathogenesis of microbial keratitis will allow the development of improved therapies. This review provides a resource for clinicians and researchers to assist in identification and readily source treatment information.

Identification and sensitivity of two rare fungal species isolated from two patients with Fusarium keratomycosis

We report two cases of Fusarium keratomycosis in which molecular analysis was used to identify two rare causative Fusarium species. A 65-year-old woman was diagnosed with Fusarium keratomycosis caused by F. equiseti, confirmed by sequencing the internal transcribed spacer (ITS) region and morphological characteristics. She was initially treated with topical corticosteroid but the keratitis did not improve. Even after aggressive antifungal treatment, there was a severe reduction of vision. In the end, the eye perforated. Our second case was a 75-year-old man who had diabetes mellitus. He developed keratitis after his cornea was injured by corn stalks. The ITS region identified the causative organism as F. verticillioides. Unlike the first case, he had good visual recovery after early antifungal therapy. Our findings demonstrate that both ITS and morphological characteristics can be used to identify the exact Fusarium species causing Fusarium keratomycosis. This allowed us to determine the sensitivity of these species to antifungal drugs that can be used to treat patients with these species of Fusarium.

A prototype antifungal contact lens

PURPOSE

To design a contact lens to treat and prevent fungal ocular infections.

METHODS

Curved contact lenses were created by encapsulating econazole-impregnated poly(lactic-co-glycolic) acid (PLGA) films in poly(hydroxyethyl methacrylate) (pHEMA) by ultraviolet photopolymerization. Release studies were conducted in phosphate-buffered saline at 37°C with continuous shaking. The contact lenses and their release media were tested in an antifungal assay against Candida albicans. Cross sections of the pre- and postrelease contact lenses were characterized by scanning electron microscopy and by Raman spectroscopy.

RESULTS

Econazole-eluting contact lenses provided extended antifungal activity against Candida albicans fungi. Fungicidal activity varied in duration and effectiveness depending on the mass of the econazole-PLGA film encapsulated in the contact lens.

CONCLUSIONS

An econazole-eluting contact lens could be used as a treatment for fungal ocular infections.

Penetration of topically administered 0.5-percent caspofungin eye drops into human aqueous humor

Ten participants attending elective anterior segment eye surgery received 0.5% caspofungin eye drops either 1 drop hourly for 4 h or 1 drop an hour before surgery. The eye drops were generally well tolerated. In the absence of inflammation or corneal abrasion, topical caspofungin does not achieve clinically relevant concentrations.

Melanized fungi in human disease

Melanized or dematiaceous fungi are associated with a wide variety of infectious syndromes, including chromoblastomycosis, mycetoma, and phaeohyphomycosis. [corrected]. Many are soil organisms and are generally distributed worldwide, though certain species appear to have restricted geographic ranges. Though they are uncommon causes of disease, melanized fungi have been increasingly recognized as important pathogens, with most reports occurring in the past 20 years. The spectrum of diseases with which they are associated has also broadened and includes allergic disease, superficial and deep local infections, pneumonia, brain abscess, and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common etiologic fungi. Melanin is a likely virulence factor for these fungi. Diagnosis relies on careful microscopic and pathological examination, as well as clinical assessment of the patient, as these fungi are often considered contaminants. Therapy varies depending upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Triazoles such as voriconazole, posaconazole, and itraconazole have the most consistent in vitro activity. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.

Clinical utility of voriconazole eye drops in ophthalmic fungal keratitis

Fungal keratitis is one of the major causes of ophthalmic mycosis and is difficult to treat. The range of common antifungal agents available for fungal keratitis remains inadequate and is generally associated with poor clinical outcomes. Voriconazole is a new generation triazole antifungal agent. Only marketed in systemic formulation and, with broad-spectrum activity and high intraocular penetration, voriconazole has demonstrated effectiveness against fungal keratitis. Systemic voriconazole, however, is not without side effects and is costly. Voriconazole eye drops have been prepared extemporaneously and used for the treatment of ophthalmic fungal keratitis. The current article sought to review the literature for evidence related to the effectiveness and safety of topical voriconazole and its corneal penetration into the aqueous humor of the eye. The voriconazole eye drops used are typically of 1% concentration, well tolerated by the eye, and are stable. Despite existing evidence to suggest that the eye drops are effective in the treatment of fungal keratitis, more studies are needed, especially in relation to using the eye drops as first-line and stand-alone treatment, preparation of higher concentrations, and optimal dosing frequency.

Treatment of Corneal Ulcers: What are the Medical Options?

Practical relevance Corneal ulcers in cats (ulcerative keratitis) are a common presenting complaint, and are a frequent sequela to feline herpesvirus (FHV-1) infection. In fact, it is fair to assume an FHV-1 aetiology until proven otherwise. In practice, therefore, many cases of corneal ulceration can be treated medically, but treatment can frequently be challenging, with the need to tailor therapy carefully to the type of ulcer, the individual cat and its temperament.

Patient group All age groups and breeds can suffer with ulcerative keratitis although some breeds are over-represented for some types of corneal ulceration.

Evidence base The scientific literature on feline ulcerative keratitis is extensive, particularly that related to FHV-1 infection. This article reviews the medical treatment options for corneal ulceration in cats with reference to the current evidence base.

Intravitreal injection of therapeutic agents

BACKGROUND

Intravitreal injection (IVI) with administration of various pharmacological agents is a mainstay of treatment in ophthalmology for endopthalmitis, viral retinitis, age-related macular degeneration, cystoid macular edema, diabetic retinopathy, uveitis, vascular occlusions, and retinal detachment. The indications and therapeutic agents are reviewed in this study.

METHODS

A search of the English, German, and Spanish language MEDLINE database was conducted. A total of 654 references spanning the period through early 2008 were individually evaluated.

RESULTS

The advantage of the IVI technique is the ability to maximize intraocular levels of medications and to avoid the toxicities associated with systemic treatment. Intravitreal injection has been used to deliver several types of pharmacological agents into the vitreous cavity: antiinfective and antiinflammatory medications, immunomodulators, anticancer agents, gas, antivascular endothelial growth factor, and several others. The goal of this review is to provide a detailed description of the properties of numerous therapeutic agents that can be delivered through IVI, potential complications of the technique, and recommendations to avoid side effects.

CONCLUSION

The IVI technique is a valuable tool that can be tailored to the disease process of interest based on the pharmacological agent selected. This review provides the reader with a comprehensive summary of the IVI technique and its multitude of uses.

In vitro antifungal activity of the fourth generation fluoroquinolones against Candida isolates from human ocular infections

PURPOSE

To evaluate and compare the in vitro antifungal activity of moxifloxacin and gatifloxacin against Candida species isolated from ocular infections.

METHODS

Tube microdilutions test was used to determine antifungal activity of the agents for 21 Candida isolates and one quality control strain. Drugs evaluated included topical preparations of fluoroquinolones (FQs), moxifloxacin (Vigamox), and gatifloxacin (Zymar). Serial dilutions of moxifloxacin (0.5%, 0.25%, 0.125%) and gatifloxacin (0.3%, 0.15%, 0.075%) were prepared for the microtube dilutions test. Aliquots (0.01 ul) were plated onto Sabouraud agar and colonies were counted.

RESULTS

Both drugs undiluted inhibited greater than 95% of growth at 24 hrs. There was no significant difference between moxifloxacin and gatifloxacin at undiluted concentrations (p = 1.00); however, the mean number of colony forming units in gatifloxacin group was significantly less than that of moxifloxacin at diluted concentrations of the drugs (p < 0.05).

CONCLUSIONS

Current commercial topical preparations of moxifloxacin and gatifloxacin demonstrated a definite in vitro antifungal activity against ocular Candida species; however, clinical efficacy of these agents remains unproven. The greater inhibition of growth of organisms with gatifloxacin compared to moxifloxacin is possibly because of the presence of BAK in Zymar.

Fungal Keratitis: Emerging Trends and Treatment Outcomes

PURPOSE

To review the trends, risk factors, causative organisms, treatment, and outcomes of fungal keratitis at the authors' institution.

METHODS

A retrospective review of the records of consecutive patients diagnosed with fungal keratitis at the authors' institution from January 1999 to June 2006.

RESULTS

Eighty-four patients were diagnosed with fungal keratitis during this period. The average age of the patients was 48 years, and 64% were male. Until 2004, trauma (51%) and contact lens use (40%) were the major risk factors. After 2005, contact lens use (52%) surpassed trauma as the most common risk factor (29%). The percentage of fungal ulcers caused by nontherapeutic contact lenses increased from 21% between 1999 and 2001 to 32% between 2002 and 2004 and to 45% in 2005 and 2006. Eighty-six percent of cultured organisms were filamentous. Fusarium (41%) was the most commonly isolated genus, followed by Candida (14%), Curvularia (12%), and Aspergillus (12%). Visual acuity was worse than 20/200 in 56% of patients at presentation. Final visual acuity was 20/40 or better in 70% of patients treated with medication alone and 16% of patients requiring therapeutic keratoplasty. Surgical intervention in the acute phase was necessary in 23% of patients. Seventy-four percent of medically treated patients had dual topical antifungal therapy. Natamycin 5% and amphotericin B 0.15% were the most commonly used drugs.

CONCLUSIONS

Contact lenses are a major risk factor for fungal keratitis. The incidence of contact lens-related fungal keratitis was increasing even before the Fusarium outbreak in 2005 and 2006. Good visual outcomes can be achieved by aggressive dual topical antifungal therapy.

Calcineurin promotes infection of the cornea by Candida albicans and can be targeted to enhance fluconazole therapy

In an established Candida albicans murine keratitis model, combination therapy with ophthalmic preparations of fluconazole and cyclosporine A (CsA) demonstrated in vivo drug synergy and effectively resolved wild-type C. albicans infection more rapidly than monotherapy with either drug. Calcineurin, the target of CsA, was also found to contribute to pathogenicity.

Comparison of Topical Itraconazole 1% With Topical Natamycin 5% for the Treatment of Filamentous Fungal Keratitis

PURPOSE

To compare the clinical efficacy of itraconazole 1% eyedrops with a standard therapy regimen (natamycin 5% eyedrops) for topical monotherapy of fungal keratitis.

METHODS

Patients presenting with suspected uniocular microbial keratitis over a period of 12 months (January to December 2002) underwent detailed clinical examination and microbiological investigation. One hundred consecutive patients with direct smear- and/or culture-proven fungal keratitis were enrolled in the study after obtaining informed consent. The ulcers were categorized as severe or nonsevere. The first 50 consecutive patients received primary therapy with topical natamycin hourly, and the next 50 consecutive patients received topical itraconazole hourly. The primary efficacy criteria were the physician's judgment of clinical success, cure rate, and the rate of treatment failure.

RESULTS

The diagnosis of fungal keratitis was established by positive microscopy and culture findings in 88 patients and by positive microscopy alone in 12 patients. Species of Fusarium, Aspergillus, and Curvularia were the principal isolates. Thirty-six (72%) of 50 patients (28 of 37 with nonsevere keratitis and 8 of 13 with severe keratitis) showed a favorable response to primary natamycin therapy (mean duration, 20.5 days), while 30 (60%) of 150 patients (25 of 38 with nonsevere keratitis and 5 of 12 with severe keratitis) exhibited a favorable response to primary itraconazole therapy (mean duration, 23.1 days). In keratitis due to Fusarium spp, 19 (79%) of 24 patients showed a favorable response to natamycin, which was significantly greater than the 8 (44%) of 18 patients who showed a favorable response to itraconazole (P < 0.02). However, no such difference was evident in keratitis due to Aspergillus spp or Curvularia spp; in keratitis due to Aspergillus spp, favorable responses were noted in 6 (54.5%) of 11 patients receiving natamycin and 5 (50%) of 10 patients receiving itraconazole, while in keratitis due to Curvurlaria spp, such responses occurred in both patients receiving natamycin and in 8 (89%) of 9 patients receiving itraconazole. Both antifungal formulations were generally well tolerated with no obvious adverse effects.

CONCLUSIONS

Topical natamycin should continue to be considered as the treatment of choice for filamentous fungal keratitis; when natamycin is unavailable, topical itraconazole therapy could be used, particularly if the infections are due to Aspergillus or Curvularia spp.

Antifungal therapy for keratomycoses

Keratomycoses have recently emerged as an important cause of ocular morbidity, especially in third-world countries. Available antifungal agents are limited in their efficacy, due to limited penetration into the cornea, the fungistatic nature and the development of drug resistance. Effective usage of the available drugs is hampered by the inefficiency of currently available antibiotic sensitivity tests for fungal organisms. There is also limited knowledge regarding the ideal combination(s) of antifungal agents, including issues of synergism and antagonism. Despite these problems, recent publications indicate encouraging outcomes in the treatment of a large series of fungal keratitis. Advances include better drug formulations, new agents and novel methods of drug delivery into the eye. As our ability to deal with advanced fungal keratitis remains limited, the importance of early diagnosis has been stressed and molecular biological techniques may play an important role in the future. This article summarises the important new advances in these areas in the past 2 years and provides guidelines for the management of these serious corneal infections.

Current perspectives on ophthalmic mycoses

Fungi may infect the cornea, orbit and other ocular structures. Species of Fusarium, Aspergillus, Candida, dematiaceous fungi, and Scedosporium predominate. Diagnosis is aided by recognition of typical clinical features and by direct microscopic detection of fungi in scrapes, biopsy specimens, and other samples. Culture confirms the diagnosis. Histopathological, immunohistochemical, or DNA-based tests may also be needed. Pathogenesis involves agent (invasiveness, toxigenicity) and host factors. Specific antifungal therapy is instituted as soon as the diagnosis is made. Amphotericin B by various routes is the mainstay of treatment for life-threatening and severe ophthalmic mycoses. Topical natamycin is usually the first choice for filamentous fungal keratitis, and topical amphotericin B is the first choice for yeast keratitis. Increasingly, the triazoles itraconazole and fluconazole are being evaluated as therapeutic options in ophthalmic mycoses. Medical therapy alone does not usually suffice for invasive fungal orbital infections, scleritis, and keratitis due to Fusarium spp., Lasiodiplodia theobromae, and Pythium insidiosum. Surgical debridement is essential in orbital infections, while various surgical procedures may be required for other infections not responding to medical therapy. Corticosteroids are contraindicated in most ophthalmic mycoses; therefore, other methods are being sought to control inflammatory tissue damage. Fungal infections following ophthalmic surgical procedures, in patients with AIDS, and due to use of various ocular biomaterials are unique subsets of ophthalmic mycoses. Future research needs to focus on the development of rapid, species-specific diagnostic aids, broad-spectrum fungicidal compounds that are active by various routes, and therapeutic modalities which curtail the harmful effects of fungus- and host tissue-derived factors.