Staphylococcal Enterotoxins Promote Virulence in Bacterial Keratitis.

Purpose: Staphylococcus aureus is an important cause of corneal infections (keratitis). To better understand the virulence mechanisms mediating keratitis, a recent comparative genomics study revealed that a set of secreted enterotoxins were found with higher prevalence among ocular versus non-ocular S. aureus clinical infection isolates, suggesting a key role for these toxins in keratitis. Although well known to cause toxic shock syndrome and S. aureus food poisoning, enterotoxins have not yet been shown to mediate virulence in keratitis. Methods: A set of clinical isolate test strains, including a keratitis isolate that encodes five enterotoxins (sed, sej, sek, seq, ser), its corresponding enterotoxin deletion mutant and complementation strain, a keratitis isolate devoid of enterotoxins, and the non-ocular S. aureus strain USA300 along with its corresponding enterotoxin deletion and complementation strains, were evaluated for cellular adhesion, invasion and cytotoxicity in a primary corneal epithelial model as well as with microscopy. Additionally, strains were evaluated in an in vivo model of keratitis to quantify enterotoxin gene expression and measure disease severity. Results: We demonstrate that, although enterotoxins do not impact bacterial adhesion or invasion, they do elicit direct cytotoxicity in vitro toward corneal epithelial cells. In an in vivo model, sed, sej, sek, seq, ser were found to have variable gene expression across 72 hours of infection and test strains encoding enterotoxins resulted in increased bacterial burden as well as a reduced host cytokine response. Conclusions: Our results support a novel role for staphylococcal enterotoxins in promoting virulence in S. aureus keratitis.

Clinical Manifestations of Monkeypox.

Monkeypox is a global health issue caused by the monkeypox virus. It can spread from person to person through respiratory secretions, direct exposure to dermatological lesions of infected patients, or exposure to contaminated objects. It is more common in homosexual men, and most patients are asymptomatic. The gold standard for diagnosis is a real-time polymerase chain reaction. In the absence of testing facilities, clinicians rely upon detailed history to exclude other causes of fever with rashes. Initially, there is a prodrome phase of a few days, which is followed by the appearance of rashes. The dermatological manifestations are in the form of an exanthematous rash, which transforms through a macular, papular, and vesicular phase and disappears after crusting in approximately 3 weeks. There can be associated lymphadenopathy in these patients. Respiratory manifestations include nasal congestion and shortness of breath that may result in secondary bacterial infections. Additionally, patients can have neurological involvement in the form of encephalitis. Furthermore, ocular involvement can occur in the form of conjunctivitis, keratitis, and corneal ulceration. Other symptoms can include diarrhea, vomiting, myalgia, and backache. Since most patients do not require hospitalization, the approach to treatment is mainly vigilant monitoring, antiviral therapy, and management of associated complications.

Determination of probability of causative pathogen in infectious keratitis using deep learning algorithm of slit-lamp images.

Corneal opacities are important causes of blindness, and their major etiology is infectious keratitis. Slit-lamp examinations are commonly used to determine the causative pathogen; however, their diagnostic accuracy is low even for experienced ophthalmologists. To characterize the "face" of an infected cornea, we have adapted a deep learning architecture used for facial recognition and applied it to determine a probability score for a specific pathogen causing keratitis. To record the diverse features and mitigate the uncertainty, batches of probability scores of 4 serial images taken from many angles or fluorescence staining were learned for score and decision level fusion using a gradient boosting decision tree. A total of 4306 slit-lamp images including 312 images obtained by internet publications on keratitis by bacteria, fungi, acanthamoeba, and herpes simplex virus (HSV) were studied. The created algorithm had a high overall accuracy of diagnosis, e.g., the accuracy/area under the curve for acanthamoeba was 97.9%/0.995, bacteria was 90.7%/0.963, fungi was 95.0%/0.975, and HSV was 92.3%/0.946, by group K-fold validation, and it was robust to even the low resolution web images. We suggest that our hybrid deep learning-based algorithm be used as a simple and accurate method for computer-assisted diagnosis of infectious keratitis.

Development of Cytomegalovirus Corneal Endotheliitis During Long-Term Topical Tacrolimus and Steroid Treatment for Chronic Ocular Surface Inflammatory Diseases.

PURPOSE: We report 3 cases of patients with chronic ocular surface inflammatory disease who developed cytomegalovirus (CMV) corneal endotheliitis during immunosuppressant and steroid treatment. PATIENTS AND METHODS: This is a retrospective observational study analyzing the clinical characteristics and outcomes of 3 patients with ocular surface inflammatory diseases (2 with Mooren ulcer and 1 with idiopathic scleritis) who developed CMV corneal endotheliitis. All patients developed CMV corneal endotheliitis between 8 and 14 months of starting steroid and immunosuppressant treatment, including topical 0.1% tacrolimus. Decimal visual acuity, endothelial counts, and intraocular pressure were analyzed. RESULTS: All patients received topical 0.5% ganciclovir after the diagnosis of CMV corneal endotheliitis, which improved endothelial inflammation. However, all patients developed irreversible mydriasis and required additional surgeries, including endothelial keratoplasty, cataract surgery, and glaucoma surgery. At the final follow-up (14-46 months post-CMV corneal endotheliitis onset), fair outcomes were achieved, as demonstrated by a mean decimal best-corrected visual acuity of 0.3 and a well-controlled intraocular pressure. CONCLUSIONS: Topical steroids and immunosuppressants can induce fulminant CMV corneal endotheliitis with cataract progression and irreversible mydriasis. In these cases, early diagnosis and treatment, including topical 0.5% ganciclovir, glaucoma surgery, cataract surgery, and endothelial keratoplasty, are necessary for preserving the patient's vision.

Pathobiology and treatment of viral keratitis.

Keratitis is one of the most prevalent ocular diseases manifested by partial or total loss of vision. Amongst infectious (viz., microbes including bacteria, fungi, amebae, and viruses) and non-infectious (viz., eye trauma, chemical exposure, and ultraviolet exposure, contact lens) risk factors, viral keratitis has been demonstrated as one of the leading causes of corneal opacity. While many viruses have been shown to cause keratitis (such as rhabdoviruses, coxsackieviruses, etc.), herpesviruses are the predominant etiologic agent of viral keratitis. This chapter will summarize current knowledge on the prevalence, diagnosis, and pathobiology of viral keratitis. Virus-mediated immunomodulation of host innate and adaptive immune components is critical for viral persistence, and dysfunctional immune responses may cause destruction of ocular tissues leading to keratitis. Immunosuppressed or immunocompromised individuals may display recurring disease with pronounced severity. Early diagnosis of viral keratitis is beneficial for disease management and response to treatment. Finally, we have discussed current and emerging therapies to treat viral keratitis.

Characteristics of Corneal Endotheliitis among Different Viruses by in Vivo Confocal Microscopy.

Objectives: To explore the cellular morphological characteristics and changes in corneal endotheliitis among different viruses by in vivo confocal microscopy (IVCM).Methods: Corneal confocal images of 44 eyes of 44 patients with HSV, VZV, CMV and EBV corneal endotheliitis were studied retrospectively. Corneal confocal images of 44 normal eyes were used as controls.Results: The pathogens included cytomegalovirus (n = 20), herpes simplex virus (n = 8), varicella zoster virus (n = 10), and Epstein Barr virus (n = 6). There were no differences in the evaluated structures among the different viruses except for the lengths of the subbasal nerves and Langerhans cell densities. Deviations in endothelial cell layers were not significant among different viruses except for owl's eye morphology.Conclusion: ICVM can assist in diagnosing endotheliitis. The results demonstrate that changes in the cornea were not different among the various viruses except for owl's eye morphology, the lengths of the subbasal nerves and Langerhans cell densities.

Viral Kerato-Uveitis with Choroidal Vitiligo.

Purpose: To describe unusual fundus findings in typical varicella zoster (VZV) kerato-uveitis.Methods: Observational, retrospective case study of five patients diagnosed with VZV kerato-uveitis.Results: Four out of five cases had a history of typical herpes zoster ophthalmicus skin rash over the forehead. All five patients had stromal keratitis, granulomatous keratic precipitates, and mild-moderate anterior chamber reaction, and two cases had typical VZV-iris atrophic changes. All cases demonstrated clear vitreous and multiple hypopigmented choroidal lesions (MHCL) with indistinct borders only in the affected eyes. Imaging studies failed to demonstrate evidence of active or resolved choroiditis. MHCL remained status quo in all including two cases who had recurrences of kerato-uveitis.Conclusion: We describe previously unreported novel fundus finding, MHCL in typical VZV-kerato-uveitis cases. We presume MHCL are due to loss of melanin from choroidal melanocytes secondary to the VZV infection and propose a term "choroidal vitiligo" to describe these novel fundus findings.

Cytomegalovirus Endotheliitis After Penetrating Keratoplasty.

Cytomegalovirus (CMV)-related corneal endotheliitis is an inflammation of the corneal endothelium caused by CMV. It may occur de novo or after ocular surgery in otherwise healthy individuals. In patients who have undergone keratoplasty, the differential diagnosis of viral endotheliitis and immune-related graft rejection is challenging due to the similar clinical findings. Here we report a patient who underwent penetrating keratoplasty and was using local and systemic immunosuppressive agents due to previous history of graft rejection. At postoperative year 4, ophthalmologic examination revealed localized corneal edema, coin-shaped keratic precipitates, and increased intraocular pressure, consistent with viral endotheliitis. Polymerase chain reaction revealed CMV-DNA amplification in the aqueous humor sample. Valganciclovir treatment was started and the symptoms improved in 2 months. It should be kept in mind that local or systemic immunosuppressants used after keratoplasty may trigger CMV reactivation. Anti-CMV treatment should be initiated immediately in patients with coin-shaped keratic precipitates.

[Ocular manifestations of measles in adults: About three cases]. / Manifestations oculaires de la rougeole chez l'adulte : à propos de trois cas.

Measles is a contagious viral infection that usually affects children. The disease is caused by morbillivirus, a virus of the family Paramyxoviridae. The clinical picture is characterized by four phases: incubation, invasion, eruption and desquamation. Ophthalmologic manifestations in measles are rare, dominated by conjunctivitis and keratitis. Corneal involvement is the main concern; it varies from simple superficial punctate keratitis to corneal perforation. We report three cases of acute keratitis in young adults during an epidemic. The epithelial involvement was peripheral, central or diffuse. The outcome was favorable under symptomatic topical treatment.

Clinical Evaluation of Intravitreal Injection of Ganciclovir in Refractory Corneal Endotheliitis.

Purpose: To evaluate the efficacy and safety of intravitreal ganciclovir (GCV) injection in refractory endotheliitis.Methods: Retrospectively recruited 25 eyes with endotheliitis, proved by clinical manifestations, positive PCR for viral DNA and responded poor to topical and systemic antiviral medications. All patients received additional continued intravitreal GCV injections.Results: Cytomegalovirus (CMV), varicella zoster virus (VZV), and herpes simplex virus (HSV) DNA were detected in 64.0%, 28.0%, and 8.0% of the eyes, respectively. Within 2 weeks after the last injection, 16/25 eyes recovered corneal clarity; active keratic precipitates (KPs) were eliminated in 21/25 eyes; intraocular pressure (IOP) was controlled in 12/15 eyes with elevated IOP on study entry. Best-corrected visual acuity increased at the last follow-up (p = 0.016). Clinical recurrence occurred in three patients. No complications were detected.Conclusions: CMV endotheliitis was the main type of refractory endotheliitis. Despite its invasive nature, intravitreal GCV injection appears to be an effective method for refractory endotheliitis.

Genomic foundations of evolution and ocular pathogenesis in human adenovirus species D.

Human adenovirus commonly causes infections of respiratory, gastrointestinal, genitourinary, and ocular surface mucosae. Although most adenovirus eye infections are mild and self-limited, specific viruses within human adenovirus species D are associated with epidemic keratoconjunctivitis (EKC), a severe and highly contagious ocular surface infection, which can lead to chronic and/or recurrent, visually disabling keratitis. In this review, we discuss the links between adenovirus ontogeny, genomics, immune responses, and corneal pathogenesis, for those viruses that cause EKC.

The Absence of Lymphotoxin-α, a Herpesvirus Entry Mediator (HVEM) Ligand, Affects Herpes Simplex Virus 1 Infection In Vivo Differently than the Absence of Other HVEM Cellular Ligands.

Previously, we reported that the absence of herpesvirus entry mediator (HVEM) decreases latency but not primary infection in ocularly infected mice. Recently, we reported that similar to the absence of HVEM, the absence of HVEM ligands (i.e., LIGHT, CD160, and B and T lymphocyte attenuator [BTLA]) also decreased latency but not primary infection. Similar to LIGHT, CD160, and BTLA, another member of tumor necrosis factor (TNF) superfamily, lymphotoxin-α (LTα), also interacts with HVEM. To determine whether LTα decreases latency in infected mice, we ocularly infected LTα-/- mice with latency-associated transcript-positive [LAT(+)] and LAT(-) viruses using similarly infected wild-type (WT) mice as controls. In contrast to WT C57BL/6 mice, LTα-/- mice were highly susceptible to ocular herpes simplex virus 1 (HSV-1) infection, independent of the presence or absence of LAT. Survival was partially restored by adoptive transfer of CD4+, CD8+, or total T cells. Infected LTα-/- mice had significantly higher corneal scarring than WT mice, and adoptive T cell transfer did not alter the severity of eye disease. In contrast to results in WT mice, the amount of latency was not affected by the absence of LAT. The amount of LAT RNA in LTα-/- mice infected with LAT(+) virus was similar to that in WT mice, and adoptive T cell transfer did not alter LAT RNA levels in LTα-/- infected mice. Increased latency in the absence of LTα correlated with upregulation of HVEM, LIGHT, CD160, and BTLA transcripts as well as with an increase in markers of T cell exhaustion. The results of our study suggest that LTα has antipathogenic and anti-inflammatory functions and may act to protect the host from infection.IMPORTANCE Recently, we evaluated the effects of HVEM and its ligands (LIGHT, CD160, and BTLA) on HSV-1 infectivity. However, the effect of LTα, another member of the TNF superfamily, on HSV-1 latency and eye disease is not known. Here, we demonstrate increased latency and corneal scarring in LTα-/- infected mice, independent of the presence of LAT. In addition, infected mice were highly susceptible to HSV-1 infection, and survival was partially but not significantly restored by adoptive T cell transfer. These results suggest that the absence of LTα affects HSV-1 infectivity differently than the absence of HVEM, LIGHT, CD160, and BTLA.

Lassa Virus Targeting of Anterior Uvea and Endothelium of Cornea and Conjunctiva in Eye of Guinea Pig Model.

Lassa virus (LASV), a hemorrhagic fever virus endemic to West Africa, causes conjunctivitis in patients with acute disease. To examine ocular manifestations of LASV, we histologically examined eyes from infected guinea pigs. In fatal disease, LASV immunostaining was most prominent in the anterior uvea, especially in the filtration angle, ciliary body, and iris and in and around vessels in the bulbar conjunctiva and peripheral cornea, where it co-localized with an endothelial marker (platelet endothelial cell adhesion molecule). Antigen was primarily associated with infiltration of T-lymphocytes around vessels in the anterior uvea and with new vessel formation at the peripheral cornea. In animals that exhibited clinical signs but survived infection, eyes had little to no inflammation and no LASV immunostaining 6 weeks after infection. Overall, in this model, LASV antigen was restricted to the anterior uvea and was associated with mild chronic inflammation in animals with severe disease but was not detected in survivors.

Stability, safety, and pharmacokinetics of ganciclovir eye drops prepared from ganciclovir for intravenous infusion.

PURPOSE: Hospital-prepared topical ganciclovir eye drops made from intravenous infusions are used to treat cytomegalovirus corneal endotheliitis. This study assessed the efficacy of these eye drops. STUDY DESIGN: Experimental study design. METHODS: Ganciclovir solutions (0.5% and 1.0%) prepared by diluting DENOSINE® IV Infusion in saline were stored light-shielded at 4, 25, or 37°C for 12 weeks. Every two weeks during storage, macroscopic evaluation was conducted and ganciclovir concentrations were determined by high performance liquid chromatography. Ocular surface toxicity and corneal ganciclovir concentrations were evaluated following topical instillation of ganciclovir solutions in rabbits. RESULTS: Ganciclovir solutions maintained transparency for 6 weeks, with precipitation appearing after 8 weeks. Ganciclovir concentrations were maintained at ~100% for 6 weeks at 4°C and 25°C and decreased gradually to 90% after 12 weeks. At 37°C, ganciclovir concentrations decreased linearly for 12 weeks. Rabbit eyes showed no ocular surface toxicity. Following instillation of 0.5% ganciclovir solution, endothelial ganciclovir concentrations were 28.0 µg/g at one hour and 4.3 µg/g at three hours. CONCLUSIONS: Ganciclovir eye drops seem to be safe and penetrate the corneal endothelium. The drug in eye drop form is chemically stable for up to 6 weeks. Eye drops' development for approval by regulatory authorities, especially with improved long-term stability, is anticipated.

Peripheral ulcerative keratitis with corneal melt as the primary presentation in a case of human immunodeficiency virus.

Peripheral ulcerative keratitis (PUK) is an aggressive, potentially sight-threatening cause for peripheral corneal thinning. It is thought to be the result of immune complex deposition at the limbus, resulting in corneal inflammation and stromal melt. We present a case of a 43-year-old female patient of African origin, presenting with PUK and associated corneal perforation as the primary presentation of HIV infection. An urgent tectonic deep anterior lamellar keratoplasty was performed under general anaesthesia with excellent outcome. The patient was referred to the sexual health clinic and anti-retroviral treatment was initiated. This case is to the best of our knowledge the first report from the UK of PUK with corneal perforation as the primary presentation of HIV infection. As highlighted in this report, infection with HIV may initially be silent; therefore, it is vital to consider HIV infection when dealing with PUK of unknown aetiology.

Post-herpes neurotrophic keratopathy: Aetiopathogenesis, clinical signs and current therapies. / Queratopatía neurotrófica postherpética: etiopatogenia, clínica y terapias actuales.

Neurotrophic keratopathy (NK) is a degenerative corneal disease caused by damage of trigeminal innervation. This leads to epithelial defects, ulceration and, eventually, perforation. Both herpes simplex and varicella zoster keratitis are reported to be the main causes of NK. Furthermore, prognosis in this type of NK is poor. Classic clinical findings in post-herpes NK are spontaneous epithelial breakdown, round and central epithelial defects with smooth edges, stromal melting and thinning, scarring, and neovascularisation. Although several medical and surgical treatments have been reported, no therapies are currently available to definitely restore corneal sensitivity. Therefore, NK remains a challenging disease to treat. In this review a summary is presented of the pathogenesis, manifestations, and current management of post-herpes NK. The role of antiviral treatment and varicella-zoster vaccination is also discussed. A description is also presented on both medical and surgical novel therapies, such as regenerative drugs and corneal neurotization.