Viral Infection and Antiviral Treatments in Ocular Pathologies

Clinical Spectrum and Perspective in Bilateral Acute Retinal Necrosis: Systematic Review

Bilateral acute retinal necrosis (BARN) represents a broad ophthalmological field of severe retinal pathologies associated with poor visual prognosis and blindness. The purpose of this review is to examine the clinical spectrum in detail over the past few years, exploring laboratory and instrumental diagnosis, and providing useful and up-to-date guidance in this field. A systematic review of this field has been performed through the PRISMA guidelines, searching in the PUBMED database. Serological laboratory tests on blood or polymerase chain reaction (PCR) on aqueous humor or vitreous samples are crucial to identifying the underlying cause and choosing the timeliest strategic treatments. Often, the main cause remains herpesviruses, with Varicella zoster (VZV) predominating over the others. There are also other causes that one needs to be carefully aware of. Anatomical and functional recovery is unfavorable if they are not individuated in a quick time. Early diagnosis and timely treatment offer a better chance of visual improvement and the avoidance of complications. Complications worsen the visual prognosis over months and may require a surgical approach.

Bacterial pathogens and antimicrobial susceptibility in ocular infections: A study at Boru-Meda General Hospital, Dessie, Ethiopia

INTRODUCTION

The eye consists of both internal and external compartments. Several variables, including microbes, dust, and high temperatures can cause eye illnesses that can result in blindness. Bacterial eye infections continue to be a major cause of ocular morbidity and blindness, and their prevalence is periodically rising. The objective of the study was to detect bacterial pathogens and assess their susceptibility profiles to antibiotics in the ophthalmology unit of Boru-meda Hospital in Dessie, Ethiopia.

METHODS

A hospital-based cross-sectional study was conducted from February 1 to April 30, 2021, among 319 study participants with symptomatic ocular or peri-ocular infections who were enrolled using a consecutive sampling technique. After proper specimen collection, the specimen was immediately inoculated with chocolate, blood, and MacConkey agar. After pure colonies were obtained, they were identified using standard microbiological methods. The Kirby Bauer disk diffusion method was used to test antimicrobial susceptibility patterns, based on the guidelines of the Clinical and Laboratory Standards Institute.

RESULTS

The majority of participants developed conjunctivitis 126 (39.5%), followed by blepharitis 47 (14.73%), and dacryocystitis 45 (14.1%). Overall, 164 (51.4%) participants were culture positive, six (1.9%) participants had mixed bacterial isolates, giving a total of 170 bacterial isolates with an isolation rate of 53.3%. The predominant species was CoNS 47 (27.6%), followed by S. aureus 38 (22.4%) and Moraxella species 32 (18.8%). The overall Multi-Drug Resistance (MDR) rate was 62.9%, with 33 (44.6%) being gram-negative and 74 (77.1%) being gram-positive isolates.

CONCLUSION

Conjunctivitis was the dominant clinical case and CoNS, was the predominant isolate. A higher rate of MDR isolates, particularly gram-positive ones, was observed. Efficient peri-ocular or ocular bacterial infection surveillance, including microbiological laboratory data, is necessary for monitoring disease trends.

Investigation of eye flora in cats infected with Herpesvirus and Calicivirus

Background and Objectives

The ocular surface is perpetually exposed to the external environment, rendering it susceptible to microbial contamination. The ocular surface microbiota consists of non-pathogenic microorganisms that inhabit the conjunctiva and cornea. This study's objective was to extensively review the prevalence of bacterial and fungal organisms in the conjunctiva of healthy and diseased cats. (Herpes- and Calici-infected groups).

Materials and Methods

The current study was performed on 240 cats that had visited veterinary health centers (Tehran, Iran) for examination. Sterile swabs from each cat's eyes were investigated for microbiological assessment. After sample collection, viral pathogens (Herpes and Calici viruses) were isolated and identified using the PCR method. The ages of the investigated group were 3.76, 3.93, and 4.15 months.

Results

The highest frequency of bacteria in the normal, Herpes-infected/Calici-infected, and Herpes/Calici-infected groups were associated with Staphylococcus intermedius and Streptococcus agalactiae, Staphylococcus epidermidis, and Staphylococcus intermedius, respectively. In addition, it was found that the high prevalence of fungal microorganisms in the isolated samples was related to yeasts, Aspergillus (Aspergillus fumigatus, Aspergillus niger), and Penicillium species.

Conclusion

Bacterial prevalence was significantly higher in all groups than the prevalence of fungi in the eyes of cats. The statistical comparison between the study groups regarding microbial and fungal frequency showed that significant differences were found between them, such that the frequency was higher in all disease groups, against the control group. In addition, a significant relation was observed between the Herpes-infected and Calici-infected groups regarding microbial and fungal prevalence.

Understanding Acanthamoeba Keratitis: An In-Depth Review of a Sight-Threatening Eye Infection

Acanthamoeba keratitis (AK) is a rare but potentially sight-threatening corneal infection caused by the Acanthamoeba parasite. This microorganism is found ubiquitously in the environment, often in freshwater, soil, and other sources of moisture. Despite its low incidence, AK presents significant challenges due to delayed diagnosis and the complex nature of therapeutic management. Early recognition is crucial to prevent severe ocular complications, including corneal ulceration and vision loss. Diagnostic modalities and treatment strategies may vary greatly depending on the clinical manifestation and the available tools. With the growing reported cases of Acanthamoeba keratitis, it is essential for the ophthalmic community to thoroughly understand this condition for its effective management and improved outcomes. This review provides a comprehensive overview of AK, encompassing its epidemiology, risk factors, pathophysiology, clinical manifestations, diagnosis, and treatment.

Ocular involvement in highly treatment-experienced patients with HIV

Introduction: Ocular involvement in human immunodeficiency virus (HIV) infected and treatment-experienced patients is a significant concern, despite the advancements in antiretroviral therapy (ART) medication. The extended life expectancy of HIV patients has altered the spectrum of HIV-associated ocular diseases, ranging from minor issues to severe vision impairment or blindness. Therefore, understanding these complications becomes crucial in providing comprehensive medical care and quality of life improvement. HIV patients on multiple ARTs can experience various ocular disorders due to the complexity of their treatment regimens, drug toxicities, immune reconstitution, and opportunistic infections. Most worthy to consider are: cytomegalovirus (CMV) retinitis, immune recovery uveitis (IRU), keratoconjunctivitis sicca (dry eye syndrome), and HIV-associated neuroretinal disorders. Materials and methods: A retrospective clinical investigation was conducted on HIV/AIDS-infected patients from January 1, 2013, to December 31, 2023. The study included 62 patients over 18 years, who tested HIV-positive via enzyme-linked immunosorbent assay (ELISA) and confirmed by Western blot (WB), with assessments of HIV plasma viral load (VL) and CD4+ T cell counts (CD4). Data collected included demographics, pathological histories, clinical characteristics, blood tests, assessments for opportunistic infections, patient staging, antiretroviral therapy initiation, and disease prognosis. Results: The study found that of most patients, 37 were aged 30-39 (59.7%), with 59.7% males and 40.3% females. Most had been living with HIV for 10-19 years (35.5%). Initial CD4 counts were < 200 cells/mm3 in 46.8% of patients, which improved to 19.3% when the study was done. CMV retinitis prevalence decreased from 46.8% initially to 35.5% despite ART. Other conditions included ocular toxoplasmosis (3.22%), tuberculosis-related uveitis (1,6%), keratoconjunctivitis sicca (19.3%), and HIV retinopathy (29%). Notably, 62.1% of CMV retinitis patients experienced significant visual acuity reduction. Oral valganciclovir was beneficial for patients with CMV disease affecting multiple sites and effective for both induction and maintenance therapy of CMV retinitis. Conclusions: Managing ocular complications in HIV-experienced patients requires a multidisciplinary approach with regular ophthalmologic evaluations, prompt treatment of infections, and continuous monitoring of ART effectiveness. Early detection and intervention are crucial for preserving vision and improving outcomes. The study highlighted the importance of constant monitoring even after viral suppression. Abbreviations: HIV = Human immunodeficiency virus, ART = antiretroviral therapy, CMV = cytomegalovirus, IRU = immune recovery uveitis, ELISA = enzyme-linked immunosorbent assay, WB = Western Blot, VL = viral load, CD4 = CD4+ T cells.

Anti-Staphylococcal Biofilm Effects of a Liposome-Based Formulation Containing Citrus Polyphenols

Biofilms are surface-associated microbial communities embedded in a matrix that is almost impenetrable to antibiotics, thus constituting a critical health threat. Biofilm formation on the cornea or ocular devices can lead to serious and difficult-to-treat infections. Nowadays, natural molecules with antimicrobial activity and liposome-based delivery systems are proposed as anti-biofilm candidates. In this study, the anti-biofilm activity of a formulation containing citrus polyphenols encapsulated in liposomes was evaluated against Staphylococcus aureus and Staphylococcus epidermidis, the most common agents in ocular infections. The formulation activity against planktonic staphylococci was tested by broth microdilution and sub-inhibitory concentrations were used to evaluate the effect on biofilm formation using the crystal violet (CV) assay. The eradicating effect of the preparation on mature biofilms was investigated by the CV assay, plate count, and confocal laser scanning microscopy. The product was bactericidal against staphylococci at a dilution of 1:2 or 1:4 and able to reduce biofilm formation even if diluted at 1:64. The formulation also had the ability to reduce the biomass of mature biofilms without affecting the number of cells, suggesting activity on the extracellular matrix. Overall, our results support the application of the used liposome-encapsulated polyphenols as an anti-biofilm strategy to counter biofilm-associated ocular infections.

The Host-Pathogen Interplay: A Tale of Two Stories within the Cornea and Posterior Segment

Ocular infectious diseases are an important cause of potentially preventable vision loss and blindness. In the following manuscript, we will review ocular immunology and the pathogenesis of herpesviruses and Pseudomonas aeruginosa infections of the cornea and posterior segment. We will highlight areas of future research and what is currently known to promote bench-to-bedside discoveries to improve clinical outcomes of these debilitating ocular diseases.