Detection of Acanthamoeba spp. using carboxylesterase antibody and its usage for diagnosing Acanthamoeba-keratitis

Contact lens usage has contributed to increased incidence rates of Acanthamoeba keratitis (AK), a serious corneal infection that can lead to blindness. Since symptoms associated with AK closely resemble those incurred by bacterial or fungal keratitis, developing a diagnostic method enabling rapid detection with a high degree of Acanthamoeba-specificity would be beneficial. Here, we produced a polyclonal antibody targeting the carboxylesterase (CE) superfamily protein secreted by the pathogenic Acanthamoeba and evaluated its diagnostic potential. Western blot analysis revealed that the CE antibody specifically interacts with the cell lysates and conditioned media of pathogenic Acanthamoeba, which were not observed from the cell lysates and conditioned media of human corneal epithelial (HCE) cells, Fusarium solani, Staphylococcus aureus, and Pseudomonas aeruginosa. High titers of A. castellanii-specific antibody production were confirmed sera of immunized mice via ELISA, and these antibodies were capable of detecting A. castellanii from the cell lysates and their conditioned media. The specificity of the CE antibody was further confirmed on A. castellanii trophozoites and cysts co-cultured with HCE cells, F. solani, S. aureus, and P. aeruginosa using immunocytochemistry. Additionally, the CE antibody produced in this study successfully interacted with 7 different Acanthamoeba species. Our findings demonstrate that the polyclonal CE antibody specifically detects multiple species belong to the genus Acanthamoeba, thus highlighting its potential as AK diagnostic tool.

Infectious Keratitis Associated with Contact Lenses

The use of contact lenses for correcting refraction, suppressing myopia progression, and cosmetic purposes is increasing steadily. Contact lenses have various effects on the corneal surface and corneal infection can occur following obstruction of tear flow, micro-damage to corneal epithelial cells, corneal hypoxia, changes in corneal immunity, and exposure to contaminants. When a patient who used to wear contact lenses presents with keratitis, it is important to distinguish whether it is an infection; if it is an infection, it is important to find the causative strain and promptly treat it appropriately. Since improper lens care is related to infection, appropriate patient education is necessary, and the risk of contact lens infection should be reduced through regular ophthalmic examinations.

Incidence of Corneal Inflammation of Varying Severity among Contact Lens Wearers

The human cornea is an avascular, transparent tissue that permits or allows light rays to enter or reach the retina. The cornea is made up of several layers, each of which plays an important role in preserving the transparency and power of cornea. The epithelium, Bowmans layer, Descemet’s membrane and endothelium are the layers of the cornea. This study aimed to discover the incidences of severe and non-severe corneal inflammation amongst wearers of modern technology touch lenses. Studies on touch lens users providing with a corneal ulcer/infiltrates were reported. On the basis of severity, a medical severity matrix was utilized among cases of severe and non-severe corneal inflammation. There was a large distinction in severe corneal infection among ew-hydrogel and ew-silicone hydrogel. When it comes to evaluating touch lens-related corneal inflammation, a medical severity matrix is available in hand. Wearers of contact lenses who sleep with them have a appreciably low risk of severe corneal inflammation than those who simplest put on lenses for the duration of the day. Those cases who everyday sleep with lenses have a 5-fold lower risk of severe corneal inflammation as compared day-to-day hydrogel lenses for prolonged utilization.

Malignant Keratitis Caused by a Highly-Resistant Strain of Fusarium Tonkinense from the Fusarium Solani Complex

Fusarium spp. are moulds ubiquitously distributed in nature and only occasionally pathogenic for humans. Species of the Fusarium solani complex are the predominant keratitis-inducing pathogens, because they are endowed with proper virulence factors. These fungi can adhere to the cornea creating a biofilm and, with the help of enzymes and cytotoxins, penetrate the cornea. Whereas an intact cornea is hardly able to be invaded by Fusarium spp. in spite of appropriate virulence factors, these opportunistic fungi may profit from predisposing conditions, for example mechanical injuries. This can lead to a progressive course of corneal infection and may finally affect the whole eye up to the need for enucleation. Here, we present and discuss the clinical, microbiological and histopathological aspects of a particular case due to Fusarium tonkinense of the Fusarium solani complex with severe consequences in a patient without any obvious predisposing factors. A broad portfolio of antifungal agents was applied, both topically and systemically as well as two penetrating keratoplasties were performed. The exact determination of the etiologic agent of the fungal infection proved likewise to be very challenging.

Evaluation of Amebicidal and Cysticidal Activities of Antifungal Drug Isavuconazonium Sulfate against Acanthamoeba T4 Strains

Acanthamoeba species of amebae are often associated with Acanthamoeba keratitis, a severe corneal infection. Isavuconazonium sulfate is an FDA-approved drug for the treatment of invasive aspergillosis and mucormycosis. This prodrug is metabolized into the active isavuconazole moiety. Isavuconazole was previously identified to have amebicidal and cysticidal activity against Acanthamoeba T4 strains, but the activity of its prodrug, isavuconazonium sulfate, against trophozoites and cysts remains unknown. Since it is not known if isavuconazonium can be metabolized into isavuconazole in the human eye, we evaluated the activities of isavuconazonium sulfate against trophozoites and cysts of three T4 genotype strains of Acanthamoeba. Isavuconazonium displayed amebicidal activity at nanomolar concentrations as low as 1.4 nM and prevented excystation of cysts at concentrations as low as 136 μM. We also investigated the cysticidal activity of isavuconazonium sulfate in combination with a currently used amebicidal drug polyhexamethylene biguanide (PHMB). Although combination of isavuconazonium with PHMB did not elicit an obvious synergistic cysticidal activity, the combination did not cause an antagonistic effect on the cysts of Acanthamoeba T4 strains. Collectively, these findings suggest isavuconazonium retains potency against Acanthamoeba T4 strains and could be adapted for Acanthamoeba keratitis treatment.

Analysis of Risk Factors for Cytomegalovirus Corneal Infection

Objectives: The present study assessed the risk factors for cytomegalovirus (CMV) corneal infection and compared the odds ratios.Methods: This study was a retrospective case-control study (2014.12–2021.1) over a 6-year period. We reviewed the medical record data and compared the differences between the CMV-positive and virus-negative groups with regard to sex, age, first diagnosis, and ocular complications to identify factors that may be associated with CMV corneal infections. The risk factors for CMV corneal infection were analysed using the chi-squared test and binary logistic regression models.Results: Ninety CMV-positive cases and 151 virus-negative controls were involved in this study. The risk factors for CMV corneal infection were Stevens-Johnson syndrome ocular complication (OR 12.851, 95%CI, 1.435–111.111; P=0.000), a penetrating keratoplasty (PKP) (OR 4.950, 95%CI, 2.632–9.346; P=0.024, and an anterior lamellar keratoplasty (DALK) (OR 5.290, 95%CI, 1.250–22.222; P=0.022).Conclusion: Severe corneal damage (PKP or DALK) and a severe corneal inflammatory response (SJS ocular complication) may be risk factors for CMV corneal infections.

Moraxella nonliquefaciens superinfecting herpes simplex keratitis

Introduction: Moraxella nonliquefaciens ( M. nonliquefaciens) is a low pathogenicity microorganism, which rarely causes ocular infections, unless there is a predisposing factor. The main clinical manifestation of M. nonliquefaciens ocular infections is endophthalmitis and only five cases of corneal infection have been reported. This work shows an update in M. nonliquefaciens corneal infections, and the first reported case of keratitis due to M. nonliquefaciens superinfecting herpes simplex infection. Case report: A 84-year old woman with worsening of her herpes simplex keratitis, diagnosed, and treated 2 days before. The slit lamp showed deep paracentral infiltrate and hypopyon. A corneal sample was collected for culture prior to initiation of empiric antibiotic therapy with vancomycin and ceftazidime fortified, oral acyclovir, and cyclopentolate. The strain was identified as M. nonliquefaciens and topical antibiotic therapy was adjusted to ciprofloxacin and ceftazidime. After 2 weeks, the epithelial defect and the infiltrate were resolved and prednisolone was added to the regimen. As the corneal oedema and neovascularization decreased, acyclovir, and prednisolone were slowly tapered. About 4 months later, the visual outcome was 20/50 and the ophthalmic examination showed a clear cornea with a paracentral leucoma. Conclusion: Keratitis due to M. nonliquefaciens is rare and should be suspected in patients with local predisposing factors such as corneal damage or previous corneal infection. Prompt and appropriate combined treatment for the predisposing lesions and the keratitis may improve the prognosis and avoid a more aggressive approach.