Treatment of postkeratitis fusarium endophthalmitis with amphotericin B lipid complex

Antimicrobial nanomedicine for ocular bacterial and fungal infection

Ocular infection induced by bacteria and fungi is a major cause of visual impairment and blindness. Topical administration of antibiotics remains the first-line treatment, as effective eradication of pathogens is the core of the anti-infection strategy. Whereas, eye drops lack efficiency and have relatively low bioavailability. Intraocular injection may cause concurrent ocular damage and secondary infection. In addition, antibiotic-based management can be limited by the low sensitivity to multidrug-resistant bacteria. Nanomedicine is proposed as a prospective, effective, and noninvasive platform to mediate ocular delivery and combat pathogen or even resistant strains. Nanomedicine can not only carry antimicrobial agents to fight against pathogens but also directly active microbicidal capability, killing pathogens. More importantly, by modification, nanomedicine can achieve enhanced residence time and release time on the cornea, and easy penetration through corneal tissues into anterior and posterior segments of the eye, thus improving the therapeutic effect for ocular infection. In this review, several categories of antimicrobial nanomedicine are systematically discussed, where the efficiency and possibility of further embellishment and improvement to adapt to clinical use are also investigated. All in all, novel antimicrobial nanomedicine provides potent and prospective ways to manage severe and refractory ocular infections.

Successful salvage therapy of Fusarium endophthalmitis secondary to keratitis: an interventional case series

Purpose

To describe a combination of treatment modalities used for the successful eradication of Fusarium endophthalmitis.

Design

Interventional case series.

Participants

Three consecutive patients with keratitis-associated Fusarium endophthalmitis.

Methods

After failure of traditional management options, a combination of intravitreal and long-term, high-dose systemic voriconazole, topical antifungal medications, and surgical intervention, with penetrating keratoplasty, lensectomy, and endoscopic-guided pars plana vitrectomy, was administered to each patient.

Results

All three cases achieved full resolution of the infection, with a final Snellen visual acuity score of 20/50 to 20/70.

Conclusions

An aggressive combination of therapeutic modalities, including the removal of subiris abscesses, might be needed for the successful resolution of Fusarium endophthalmitis.

Fusarium keratitis acquired during travel to Namibia

Fungal infections in travelers are rare. Fusariosis has recently become an important infection of immunocompromised patients. Herein, we describe the case of an immunocompetent traveler who contracted Fusarium keratitis while in Africa.

[Successful treatment of resistant Fusarium solani keratitis with liposomal amphotericin B]

INTRODUCTION

The prognosis for Fusarium keratitis is poor. Effective drugs to treat this infection are therefore needed.

CASE REPORT

A patient presented Fusarium solani keratitis. The infection regressed with topical amphotericin B and intravenous voriconazole. Topical steroids were introduced. There was reactivation and extension of the infection, invading the anterior chamber. Steroids were discontinued and the antifungal treatment was restarted but there was continued deterioration. Recovery was achieved without surgery, with topical voriconazole, topical liposomal amphotericin B, topical natamycin, intravenous liposomal amphotericin B, and intravenous voriconazole.

CONCLUSION

Combined orally and topically administered voriconazole is a promising therapy when the minimum inhibitory concentration is approximately 2 microg/ml. Liposomal amphotericin B seems to be the most effective drug for the different infection stages. Posaconazole is a useful alternative but further investigations must be pursued.

Therapeutic effect of intracameral amphotericin B injection in the treatment of fungal keratitis

PURPOSE

To study the therapeutic efficacy of intracameral amphotericin B (ICAMB) injection in the treatment of fungal keratitis.

METHODS

Fourteen patients with fungal keratitis received ICAMB, 10 microg/0.1 mL (group A), and 17 patients received conventional treatment only (group B). Visual acuity, time to hypopyon disappearance, time to epithelial defect closure, time to final improvement, and final outcome were analyzed and compared between the 2 groups. The concentration of amphotericin B in the aqueous humor after injection was measured using high-performance liquid chromatography.

RESULTS

The mean final visual acuity (log MAR) was 1.6 +/- 1.1 in group A and 1.3 +/- 1.4 in group B (P = 0.24). The mean time to disappearance of hypopyon, epithelial defect closure, and final improvement was 9.4 +/- 9.4, 19.8 +/- 10.4, and 26.6 +/- 9.2 days in group A and 26.7 +/- 21.3 (P = 0.03), 32.6 +/- 22.8 (P = 0.08), and 52.8 +/- 38.2 days (P = 0.04) in group B, respectively. At the last follow-up, treatment success was achieved in 92.9% of group A and 82.4% of group B (P = 0.38). The mean concentration of intracameral amphotericin B was 601.6 +/- 51.3 ng/mL at 6 hours, 98.8 +/- 43.1 ng/mL at 1 day, 57.0 +/- 11.6 ng/mL at 3 days, and 52.3 +/- 8.3 ng/mL at 7 days after injection.

CONCLUSIONS

ICAMB seems to be effective in reducing time to disappearance of hypopyon and final improvement in the treatment of fungal keratitis.

Liposomal amphotericin B eye drops to treat fungal keratitis: physico-chemical and formulation stability

Local fungal infections with Candida, Fusarium, Curvularia and Aspergillus can lead to serious ulceration of the cornea and must be treated rapidly. The current treatment consists of 0.15% (w/v) amphotericin B eye drops prepared from Fungizone, containing deoxycholate, irritant for the cornea, which reduces patient compliance. Eye drops based on liposomal amphotericin B (AmBisome would be a convenient alternative; however, according to the manufacturer's instructions, AmBisome can only be kept refrigerated for 1 week after reconstitution. A longer shelf-life at ambient temperature would be preferable for a preparation made in a hospital pharmacy and delivered to patients. Thus, the possibility of storing an ophthalmic preparation of 0.5% (w/v) liposomal amphotericin B after reconstitution was investigated. After 6 months at room temperature or at +2-8 degrees C, the hydrodynamic diameter measured by quasi-elastic light scattering remained constant at 108 +/- 30 nm with a polydispersity index lower than 0.15. Amphotericin B content, checked by a validated HPLC method, was maintained between 94 and 107%. Amphotericin B and soy phosphatidylcholine proportions remained constant, indicating that the liposomes remained intact and retained the drug. These results show the feasibility of an ophthalmic preparation based on liposomal amphotericin B developed in hospital pharmacies.

Successful treatment of resistant ocular fusariosis with posaconazole (SCH-56592)

PURPOSE

To describe the successful treatment with systemic posaconazole of a series of Fusarium ocular infections refractory to other antifungal agents.

DESIGN

Retrospective, interventional case series.

METHODS

We identified three patients from three different centers who received diagnoses of Fusarium keratitis and who received systemic posaconazole after their infections failed to respond to maximal tolerated medical and surgical therapy. All patients received multiple systemic, intracameral, and topical antifungal agents, which were ineffective in controlling their infection.

RESULTS

Two patients were contact lens wearers. Two patients developed endophthalmitis. The infections of all three patients failed to respond to systemic and/or topical voriconazole treatment. One patient could not tolerate systemic voriconazole, and another experienced no marked improvement. The third discontinued treatment for both reasons. All patients were treated with oral posaconazole and experienced rapid reduction of intraocular inflammation and pain, as well as resolution of the infection without additional intervention.

CONCLUSIONS

Deep Fusarium keratitis is difficult to treat and carries a high risk of progression to endophthalmitis. Posaconazole, which exhibits excellent tissue penetration and demonstrates efficacy in the treatment of systemic Fusarium infection, was successful in treating three cases of pan-resistant keratitis and/or endophthalmitis.

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.

Effect of voriconazole on a corneal abscess caused by fusarium

PURPOSE

To describe a case of corneal abscess caused by Fusarium solani that did not respond to common antifungal agents.

METHOD

Case report.

RESULTS

Twenty days after accidental contact with vegetation, a 56-year-old man presented with a corneal abscess. Corneal ulceration developed and a perforating keratoplasty was performed. After a microbiological examination, the diagnosis of F. solani infection was made. Systemic and topical amphotericin B and fluconazole were prescribed, with no results. A new abscess formed on the transplanted graft and a wound leak developed. We administered topical and systemic voriconazole. No side-effects were observed. The choroidal detachment and the surgical transplant recovered completely in 20 days. A vascular leukoma developed at the site of the transplanted corneal abscess.

CONCLUSION

From a functional point of view, another corneal transplant will be necessary. Voriconazole was effective in treating a severe keratomycosis caused by F. solani that was resistant to other topical and systemic antifungal agents.

Emerging fungal diseases: the importance of the host

More yeasts and molds are now recognized to cause more human disease than ever before. This development is not due to a change in the virulence of these fungi, but rather to changes in the human host. These changes include immunosuppression secondary to the pandemic of HIV, the use of life-saving advances in chemotherapy and organ transplantation, and the use of corticosteroids and other immunosuppressive agents to treat a variety of diseases. Fungi that were once considered common saprophytes are now recognized as potential pathogens in these patients. This situation necessitates better communication than ever between the clinician, pathologist, and clinical mycologist to ensure the prompt and accurate determination of the cause of fungal diseases.

Human fusariosis

Fusarium species frequently implicated in human infections include F. solani, F. oxysporum and F. moniliforme. Among immunocompetent patients, tissue breakdown (as caused by trauma, severe burns or foreign body) is the risk factor for fusariosis. Infections include keratitis, onychomycosis and occasionally peritonitis and cellulitis. Treatment is usually successful and requires removal of the foreign body as well as antifungal therapy. Among immunocompromised patients, mainly patients with haematological malignancies, Fusarium spp. are the second most common pathogenic mould. Risk factors for disseminated fusariosis include severe immunosuppression (neutropenia, lymphopenia, graft-versus-host disease, corticosteroids), colonisation, tissue damage, and receipt of a graft from an HLA-mismatched or unrelated donor. Clinical presentation includes refractory fever (> 90%), skin lesions and sino-pulmonary infections ( approximately 75%). Type of skin lesions includes ecthyma-like, target, and multiple subcutaneous nodules. Skin lesions lead to diagnosis in > 50% of patients and precede fungemia by approximately 5 days. In contrast to disseminated aspergillosis, disseminated fusariosis can be diagnosed by blood cultures in 40% of patients. Histopathology reveals hyaline acute-branching septate hyphae similar to those found in aspergillosis. Mortality from fusarial infections in immunocompromised patients ranges from 50% to 80%. Host immune status is the single most important factor predicting outcome. Persistent neutropenia and corticosteroid therapy significantly affect survival. Optimal treatment has not been established. Anecdotal successes have been reported with various agents (high-dose amphotericin B, lipid-based amphotericin B formulations, itraconazole, voriconazole) and with cytokine-stimulated granulocyte transfusions. Preventing fusariosis relies on detection and treatment of cutaneous damage prior to commencing immunosuppression and decreasing environmental exposure to Fusaria (via air and water).

Corneal Concentrations following Systemic Administration of Amphotericin B and Its Lipid Preparations in a Rabbit Model

BACKGROUND

Amphotericin B (AmB) and various lipid formulations of AmB are available for the treatment of fungal infections of the eye. Currently, the recommended route of administration for the treatment of fungal keratitis is by topical application. Nevertheless, because of the risk of a difficult to treat exogenous fungal endophthalmitis, a combined topical and systemic treatment is frequently given when treating deep fungal keratitis. To date, little is known about the pure corneal availability of these drugs following systemic treatment. In this study, the corneal concentration following 7 daily doses of parenteral AmB lipid complex (ABLC) or liposomal AmB (L-AmB) was compared to that of AmB deoxycholate (D-AmB) in a rabbit model.

METHODS

Following induction of uveitis in one rabbit eye by intravitreal injection of endotoxin, daily doses of D-AmB (1 mg/kg), ABLC (5 mg/kg) or L-AmB (5 mg/kg) were given intravenously on 7 consecutive days. Five or more rabbits per treatment were used. AmB concentrations were determined by high-performance liquid chromatography (HPLC) in corneas collected at autopsy 24 h after the 7th and final dose. Data were analyzed using the Mann-Whitney U test.

RESULTS

After 7 days of treatment, mean corneal concentrations of AmB in the inflamed eyes were significantly higher (2.38 +/- 1.47 microg/g; p < 0.01) following treatment with L-AmB compared with ABLC (<0.1 microg/g) and D-AmB (0.46 +/- 0.2 microg/g). No AmB could be detected in the corneas of the non-inflamed eyes.

CONCLUSION

In our rabbit model, AmB penetration into the cornea was significantly higher after systemic administration of L-AmB compared with conventional D-AmB or ABLC.

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.

Advanced fusarium keratitis progressing to endophthalmitis

PURPOSE

To review the clinical course, treatment, and visual outcomes of keratitis with endophthalmitis caused by the filamentary fungus Fusarium.

METHOD

One hundred fifty-nine cases of Fusarium keratitis at Bascom Palmer Eye Institute between January 1, 1987 and August 21, 2000 were reviewed. Ten patients with culture-proven Fusarium keratitis progressed to endophthalmitis. All 10 underwent standard diagnostic microbiologic evaluation, and topical and oral antifungal therapy was instituted. Surgical therapy was applied when necessary. Main outcome measures included the incidence of intraocular invasion of fungal keratitis and response to treatment.

RESULTS

Ten cases of 159 Fusarium keratitis patients had intraocular involvement that was culture proven. The isolated species were Fusarium oxysporum in seven cases and Fusarium solani in two cases, and in one case, the species could not be identified. Cultures of aqueous and intraocular tissues grew Fusarium in eight cases, whereas vitreous cultures were positive in two. Nine cases had preexisting risk factors. All patients received oral ketoconazole or fluconazole and topical natamycin 5%. In two cases, intravitreal amphotericin B injections were also given. Four patients required a penetrating keratoplasty, enucleation was performed in two patients, two patients required a combination of a penetrating keratoplasty and pars plana vitrectomy, and one patient developed phthisis.

CONCLUSION

The combination therapy with oral imidazoles (fluconazole or ketoconazole) and topical natamycin is inadequate in severe Fusarium keratitis with intraocular spread. Early diagnosis and suspicion of endophthalmitis in patients with keratomycosis not responding to aggressive topical antifungal are important.

Antifungal pharmacotherapy for invasive mould infections

The incidence of invasive mould infections is increasing and is associated with significant morbidity and mortality. Among the most prevalent of these infections are those caused by Aspergillus and Fusarium species. Invasive disease caused by moulds frequently presents as a pulmonary infection, but haematogenous infection can occur. Some moulds cause cutaneous disease through either direct inoculation of the skin or secondary spread to the skin after dissemination from another body site. Early diagnosis can often be difficult and, unfortunately, diagnosis occurs late in the course of illness in many cases. Treatment options have historically been limited by the need for intravenous administration (amphotericin B), significant toxicities (amphotericin B), lack of reliable in vitro activity (e.g., amphotericin B in Fusarium and Scedosporium apiospermum infections) and relative lack of clinical experience with newer agents. The recent approval of voriconazole (Vfend, Pfizer) introduces a treatment option that demonstrates both in vitro and in vivo activity against a variety of moulds. With the recent development of the new echinocandin class of antifungal agents and newer broad-spectrum azole antifungal agents with in vitro mould activity, there is a renewed emphasis on fungal treatment strategies. Antimould therapy presents challenges in adverse effect avoidance and management, drug interactions and pharmacoeconomic considerations. Furthermore, combination therapy is being explored with these various new antifungal agents. The administration of an optimal fungicidal therapy early in the course of the illness and control of the underlying disease are vital to prevent complications and mortality from these tenacious mycoses.

Ocular distribution of intravenously administered lipid formulations of amphotericin B in a rabbit model

Little is known about the ocular penetration of amphotericin B (AMB) and its lipid formulations, the current drug of choice in fungal endophthalmitis. The ocular distribution of AMB lipid complex (ABLC), liposomal AMB (L-AMB), and AMB deoxycholate (D-AMB) was studied in a rabbit model. D-AMB (1 mg/kg of body weight/day), ABLC (5 mg/kg/day), or L-AMB (5 mg/kg/day) was given intravenously to rabbits as a single dose or as repeated daily doses on 7 consecutive days after induction of unilateral uveitis by intravitreal injection of endotoxin. AMB concentrations in aqueous humor, vitreous humor, and plasma were determined by high-pressure liquid chromatography 16 h after administration of a single dose or 24 h after the last of seven doses. After single-dose administration, L-AMB achieved at least eightfold-higher AMB concentrations in the aqueous of inflamed eyes than ABLC or D-AMB (1.21 +/- 0.58 micro g/ml versus 0.14 +/- 0.04 and 0.11 +/- 0.09 micro g/ml, respectively). At that time point no drug was detectable in the vitreous. After 7 days of treatment, the concentration of AMB in the vitreous was higher after treatment with L-AMB (0.47 +/- 0.21 micro g/ml) than after treatment with ABLC (0.27 +/- 0.18 micro g/ml) and D-AMB (0.16 +/- 0.04 micro g/ml). Similarly, AMB concentration in the aqueous was higher after repeated doses of L-AMB (0.73 +/- 0.43 micro g/ml) than after repeated doses of ABLC (0.03 +/- 0.02 micro g/ml) or D-AMB (0.13 +/- 0.06 micro g/ml). No AMB was detected in noninflamed eyes. Following systemic administration, AMB distribution to the eye is inflammation dependent and occurs sequentially, first to the aqueous and then to the vitreous. Compared to D-AMB and ABLC, L-AMB reaches higher drug concentrations in both ocular compartments.

Pharmacotherapy of fungal eye infections

Fungal eye infections are rare. Trauma associated with contamination by vegetative material, contact lens wear and long term corticosteroid use are common risk factors. The aims of treatment are to preserve visual function, which depends on the rapid diagnosis and efficient administration of appropriate antifungal therapy. This necessitates a clinical suspicion of fungal aetiology and the taking of appropriate smears and cultures as early as possible to identify the fungal organism. Currently there are three main classes of drugs available for use in fungal eye infections: polyenes, azoles as derivatives of imidazoles, and 5-fluorocytosine. Of the polyenes, amphotericin B, natamycin and nystatin are of clinical ophthalmic use. Based on better pharmacokinetic profiles and spectra of antifungal activity, the triazoles are the agents of choice. Successful treatment of fungal keratitis depends on early initiation of specific therapy consisting of topically-applied antifungal agents since topical administration is most likely to provide the best opportunity for achieving therapeutic corneal levels. Hence, the molecular weight of the various antifungal agents is of importance since it influences their ability to penetrate the corneal epithelium. Systemic administration may be necessary for resistant fungal ulcers. For fungal endophthalmitis, to preserve visual function and eliminate the fungal pathogen, topical, systemic and possibly intraocular antifungal therapy is used, although some do not recommend use of systemic agents for exogenous endophthalmitis.