Postrecall surveillance following a multistate fusarium keratitis outbreak, 2004 through 2006

Acanthamoeba keratitis - A review

This is a comprehensive review after a thorough literature search in PubMed-indexed journals, incorporating current information on the pathophysiology, clinical features, diagnosis, medical and surgical therapy, as well as outcomes of Acanthamoeba keratitis (AK). AK is a significant cause of ocular morbidity, and early diagnosis with timely institution of appropriate therapy is the key to obtaining good outcomes. The varied presentations result in frequent misdiagnosis, and co-infections can increase the morbidity of the disease. The first line of therapy continues to be biguanides and diamidines, with surgery as a last resort.

Interaction Between Amorolfine and Voriconazole Against Fusarium species

Fusarium species represent a range of fungal pathogens capable of causing diverse mycotic diseases. Relative to antibacterial drugs, few effective antifungal agents have been developed to date, and all are subject to significant limitations. As such, there is an urgent need to design novel antifungal treatments for infections caused by Fusarium spp. Herein, 15 clinical isolates, including 5 Fusarium oxysporum and 10 Fusarium solani strains, were analyzed to explore the relative inhibitory effects of different combinations of amorolfine (AMO) and voriconazole (VOR) on the growth of these fungal pathogens. These analyses were conducted by measuring minimal inhibitory concentration (MIC) values for these antifungal agents in a broth microdilution assay and by using an in vivo model of Fusarium-infected Galleria mellonella. These experiments revealed that in isolation, AMO and VOR exhibited MIC values ranging from 4 to 16 μg/mL and 2 to 8 μg/mL, respectively. However, these effective MIC values fell to 1-2 μg/mL and 0.5-2 μg/mL, respectively, when AMO and VOR were administered in combination with one another, exhibiting synergistic activity against 73.3% of analyzed Fusarium strains. Subsequent in vivo analyses conducted using the G. mellonella model further confirmed that combination VOR + AMO treatment was associated with significantly improved larval survival following Fusarium spp. infection. Together, these results serve as the first published evidence demonstrating that VOR and AMO exhibit synergistic activity against infections caused by Fusarium spp., indicating that they may represent an effective approach to antifungal disease treatment.

Microbiological Investigations of ReNu Plastic Bottles and the 2004 to 2006 ReNu With MoistureLoc-Related Worldwide Fusarium Keratitis Event

PURPOSES

The purposes of this study were to determine whether the contact lens solution RevitaLens Ocutec (containing the antimicrobial agents alexidine and polyquaternium-1) would inhibit Fusarium organisms when heated in ReNu plastic bottles; whether alexidine would inhibit Fusarium organisms when heated in non-ReNu plastic bottles; and whether an alexidine-neutralizing compound leaches from heated ReNu bottles.

METHODS

RevitaLens and an alexidine solution (0.00045%), previously stored in ReNu bottles at room temperature (RT) and 56°C, were incubated with 7 different Fusarium organisms. The alexidine solution was similarly stored in seven non-ReNu plastic bottles and incubated with these same organisms. To determine if an alexidine-neutralizing compound might be leaching from heated ReNu bottles, phosphate-buffered saline (PBS) was incubated at RT and 56°C in ReNu bottles, combined with alexidine, and then tested for anti-Fusarium capability.

RESULTS

After being heated in ReNu bottles, RevitaLens retained its anti-Fusarium capability, whereas the alexidine solution did not. The alexidine solution heated in seven non-ReNu plastic bottles retained its anti-Fusarium capability. The alexidine solution retained its anti-Fusarium capability when incubated with a PBS solution that had been heated in ReNu bottles, indicating, microbiologically, that an alexidine-neutralizing compound did not leach from the heated ReNu bottle.

CONCLUSIONS

Alexidine uniquely fails to inhibit Fusarium organisms when heated in a plastic ReNu bottle, but not in seven other plastic bottles, whereas the anti-Fusarium capability of RevitaLens (containing the antimicrobial agents alexidine and polyquaternium-1) is unaffected by heating in a ReNu bottle. There does not seem to be an alexidine-neutralizing compound leaching from heated ReNu bottles. An interaction between alexidine and its heated ReNu bottle may have been a critical factor in the worldwide ReNu with MoistureLoc-related Fusarium keratitis event of 2004 to 2006.

Emerging trends in contact lens-related infections

PURPOSE OF REVIEW

This article reviews the literature on past and recent trends in contact lens-related microbial keratitis from bacterial, fungal, and Acanthamoeba infections.

RECENT FINDINGS

Contact lens wear is the most important risk factor for microbial keratitis. Despite increased use of daily disposable contact lens wear, the incidence of bacterial ulcers related to contact lens wear remains high. Overnight contact lens wear is the leading risk factor in contact lens-related bacterial infections. There may be a trend towards increasing antibiotic resistance of Gram-positive bacteria to fourth-generation fluoroquinolones. The incidence of Acanthamoeba and fungal infections, despite resolution of two outbreaks involving multipurpose solutions, are also on the rise.

SUMMARY

Contact lens-related microbial keratitis is rising and may be associated with more severe, vision threatening, infections.

Geographic Disparities in the Etiology of Bacterial and Fungal Keratitis in the United States of America

Infectious keratitis is a serious cause of vision loss. Proper treatment of infectious keratitis requires antimicrobials that target the organism responsible for a patient's ulcer. The frequency of infection by a given organism varies by location. We examined the literature to determine geographic disparities in the etiology of bacterial and fungal keratitis in the United States of America. Bacterial keratitis makes up a greater proportion of cases in northern locations, and fungal keratitis increases in prevalence in southern locations. Gram-negative organisms make up a greater proportion of bacterial keratitis in southern locations when compared to northern locations.

Balancing antimicrobial efficacy and toxicity of currently available topical ophthalmic preservatives

Medical treatment of ophthalmic diseases relies primarily on the use of multidose drugs. Short term use is highly effective usually with little local toxicity. However, chronic use of these preparations not only increases the likelihood of microbial contamination and secondary ocular infection, but also of toxicity from the drug formulation itself. Increasing awareness of the toxicity of ophthalmic preservatives has led to an increasing variety of preservative schemes ranging from "self-preservation" to ionic buffer systems. Beyond outdated testing methods, the anti-microbial efficacy of most of these systems is poorly defined, potentially placing these preparations at an unknown risk of contamination by unmonitored, untested organisms. No uniformity in toxicity testing exists which further complicates the clinician's judgment of the risk-benefit of using a particular drug formulation. In this manuscript we examine in detail each of the current employed ophthalmic preservative regimens with respect to their known antimicrobial activity and potential toxicity, where known. We also survey the most popular ophthalmic preparations, detailing their preservation schemes as well as concentrations to help the clinician in choosing an appropriate formulation for the treatment of various ophthalmic diseases.

Fusarium infection: report of 26 cases and review of 97 cases from the literature

Fusarium species is a ubiquitous fungus that causes opportunistic infections. We present 26 cases of invasive fusariosis categorized according to the European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) criteria of fungal infections. All cases (20 proven and 6 probable) were treated from January 2000 until January 2010. We also review 97 cases reported since 2000. The most important risk factors for invasive fusariosis in our patients were compromised immune system, specifically lung transplantation (n = 6) and hematologic malignancies (n = 5), and burns (n = 7 patients with skin fusariosis), while the most commonly infected site was the skin in 11 of 26 patients. The mortality rates among our patients with disseminated, skin, and pulmonary fusariosis were 50%, 40%, and 37.5%, respectively. Fusarium solani was the most frequent species, isolated from 49% of literature cases. Blood cultures were positive in 82% of both current study and literature patients with disseminated fusariosis, while the remaining 16% had 2 noncontiguous sites of infection but negative blood cultures. Surgical removal of focal lesions was effective in both current study and literature cases. Skin lesions in immunocompromised patients should raise the suspicion for skin or disseminated fusariosis. The combination of medical monotherapy with voriconazole or amphotericin B and surgery in such cases is highly suggested.

Crossover fungal pathogens: the biology and pathogenesis of fungi capable of crossing kingdoms to infect plants and humans

The outbreak of fungal meningitis associated with contaminated methylprednisolone acetate has thrust the importance of fungal infections into the public consciousness. The predominant pathogen isolated from clinical specimens, Exserohilum rostratum (teleomorph: Setosphaeria rostrata), is a dematiaceous fungus that infects grasses and rarely humans. This outbreak highlights the potential for fungal pathogens to infect both plants and humans. Most crossover or trans-kingdom pathogens are soil saprophytes and include fungi in Ascomycota and Mucormycotina phyla. To establish infection, crossover fungi must overcome disparate, host-specific barriers, including protective surfaces (e.g. cuticle, skin), elevated temperature, and immune defenses. This review illuminates the underlying mechanisms used by crossover fungi to cause infection in plants and mammals, and highlights critical events that lead to human infection by these pathogens. Several genes including veA, laeA, and hapX are important in regulating biological processes in fungi important for both invasive plant and animal infections.

Recent outbreaks of atypical contact lens-related keratitis: what have we learned?

PURPOSE

To examine the public health implications of 2 recent outbreaks of atypical contact lens-related infectious keratitis.

DESIGN

Perspective based on the literature and authors' experience.

RESULTS

The contact lens-related Fusarium and Acanthamoeba keratitis outbreaks were each detected by dramatic rises seen in tertiary care centers in Singapore and the United States, respectively. Case-control studies of both outbreaks were able to identify a strong association with the use of different contact lens disinfection solutions. Their respective recalls resulted in a steep decline of Fusarium keratitis, but not of Acanthamoeba keratitis. Early investigations into each solution association implicated components not directly related to their primary disinfectant, but the true pathogenesis remains unknown. However, the number of Acanthamoeba cases individually attributed to each of almost all available disinfection systems exceeds the previously understood total United States incidence, suggesting other risk factors. Current standards do not require demonstration of anti-acanthamoebal activity. Yet, despite the inclusion of Fusarium in mandatory testing for solutions, current premarket testing was not predictive of the outbreak.

CONCLUSIONS

The 2 recent outbreaks of atypical contact lens-related keratitis have reinforced the value of tertiary care eye care centers in detecting early rises in rare infections and the power of adaptable, well-designed epidemiologic investigations. Although Fusarium keratitis has declined significantly with the recall of Renu with MoistureLoc (Bausch & Lomb Inc.), the persistence of Acanthamoeba keratitis demands fundamental changes in contact lens hygiene practices, inclusion of Acanthamoeba as a test organism, and contact lens disinfectant test regimens for all contact lens-related pathogens that are verifiably reflective of end user contact lens wear complications.

Trends in fungal keratitis in the United States, 2001 to 2007

OBJECTIVE

Fungal keratitis is a serious ocular infection that is considered to be rare among contact lens wearers. The recent Fusarium keratitis outbreak raised questions regarding the background rate of Fusarium-related keratitis and other fungal keratitis in this population.

DESIGN

Retrospective, multicenter case series.

PARTICIPANTS

Six hundred ninety-five cases of fungal keratitis cases who presented to 1 of 10 tertiary medical centers from 2001 to 2007.

METHODS

Ten tertiary care centers in the United States performed a retrospective review of culture-positive fungal keratitis cases at their centers between January 2001 and December 2007. Cases were identified using microbiology, pathology, and/or confocal microscopy records. Information was collected on contact lens status, method of diagnosis, and organism(s) identified. The quarterly number of cases by contact lens status was calculated and Poisson regression was used to evaluate presence of trends. The Johns Hopkins Medicine Institutional Review Board (IRB) and the IRBs at each participating center approved the research.

MAIN OUTCOME MEASURES

Quarterly number of fungal keratitis cases and fungal species.

RESULTS

We identified 695 fungal keratitis cases; 283 involved the use of contact lenses. The quarterly number of Fusarium cases increased among contact lens wearers (CLWs) during the period that ReNu with MoistureLoc (Bausch & Lomb, Rochester, NY) was on the market, but returned to prior levels after withdrawal of the product from the market. The quarterly frequency of other filamentous fungi cases showed a statistically significant increase among CLWs comparing October 2004 through June 2006 with July 2006 through December 2007 with January 2001 through September 2004 (P < 0.0001).

CONCLUSIONS

The quarterly number of Fusarium fungal keratitis cases among CLWs returned to pre-Renu with Moistureloc levels after removal of the product from the market. However, the number of other filamentous fungal keratitis cases, although small, seems to have increased among refractive CLWs. Reasons for these apparent increases are unclear.

A murine model of contact lens-associated fusarium keratitis

PURPOSE

Fusarium solani and F. oxysporum were the causative organisms of the 2005/2006 outbreak of contact lens-associated fungal keratitis in the United States. The present study was an investigation of the ability of F. oxysporum grown as a biofilm on silicone hydrogel contact lenses to induce keratitis.

METHODS

A clinical isolate of F. oxysporum was grown as a biofilm on lotrafilcon A contact lenses, and a 2-mm diameter punch was placed on the abraded corneal epithelium of either untreated or cyclophosphamide-treated C57BL/6 mice or of IL-1R1(-/-), MyD88(-/-), TLR2(-/-), or TLR4(-/-) mice. After 2 hours, the lens was removed, and corneal opacification, colony forming units (CFUs), and histopathology were evaluated.

RESULTS

C57BL/6 mice developed severe corneal opacification within 24 hours and resolved after four days. In contrast, corneal opacification progressed in cyclophosphamide-treated mice, and was associated with unimpaired fungal growth in the cornea, and with hyphae penetrating into the anterior chamber. The phenotype of MyD88(-/-) and IL-1R(-/-) mice was similar to that of cyclophosphamide-treated animals, with significantly impaired cellular infiltration and fungal clearance. Although TLR4(-/-) mice developed a cellular infiltrate and corneal opacification similar to C57BL/6 mice, the CFU count was significantly and consistently higher.

CONCLUSIONS

Fusarium grown as a biofilm on silicone hydrogel contact lenses can induce keratitis on injured corneas, with disease severity and fungal killing dependent on the innate immune response, including IL-1R1, MyD88, and TLR4.

Fusarium keratitis associated with ReNu with MoistureLoc sample kits

OBJECTIVE

To describe a patient who developed contact-lens associated Fusarium sp. keratitis associated with use of sample kits of ReNu with MoistureLoc purchased after worldwide recall of the product from the market.

METHODS

The patient's history, clinical presentation, and laboratory workup were reviewed.

RESULTS

In April 2008, a 64-year-old woman with a 45-year history of contact lens wear presented with a large central corneal infiltrate after receiving empiric antibiotic treatment before referral. Corneal and contact lens cultures revealed Fusarium sp. The patient had been using sample kits of ReNu with MoistureLoc purchased from a dollar store to clean her lenses.

CONCLUSIONS

Although a worldwide recall of ReNu with MoistureLoc occurred in May 2006, the product may still be obtained in discount stores through sale of professional sample kits. Patients with contact lens-associated keratitis should be questioned regarding specifics of their contact lens hygienic regimen.