Self-Implantable Core-Shell Microneedle Patch for Long-Acting Treatment of Keratitis via Programmed Drug Release.

Bacteria-induced keratitis is a major cause of corneal blindness in both developed and developing countries. Instillation of antibiotic eyedrops is the most common management of bacterial keratitis but usually suffers from low bioavailability (i.e., <5%) and frequent administration, due to the existence of corneal epithelial barrier that prevents large and hydrophilic drug molecules from entering the cornea, and the tear film on corneal surface that rapidly washes drug away from the cornea. Here, a self-implantable core-shell microneedle (MN) patch with programmed drug release property to facilitate bacterial keratitis treatment is reported. The pH-responsive antimicrobial nanoparticles (NPs), Ag@ZIF-8, which are capable of producing antibacterial metal ions in the infected cornea and generating oxidative stress in bacteria, are loaded in the dissolvable core, while the anti-angiogenic drug, rapamycin (Rapa), is encapsulated in the biodegradable shell, thereby enabling rapid release of Ag@ZIF-8 NPs and sustained release of Rapa after corneal insertion. Owing to the programmed release feature, one single administration of the core-shell MN patch in a rat model of bacterial keratitis, can achieve satisfactory antimicrobial activity and superior anti-angiogenic and anti-inflammation effects as compared to daily topical eyedrops, indicating a great potential for the infectious keratitis therapy in clinics.

Mesenchymal stem cell-based adjunctive therapy for Pseudomonas aeruginosa-induced keratitis: A proof-of-concept in-vitro study.

PURPOSE: Pseudomonas aeruginosa-induced keratitis is one of the most severe and challenging forms of corneal infection, owing to its associated intense inflammatory reactions leading to corneal necrosis and dense corneal scar with loss of vision. Since mesenchymal stem cells (MSCs) are reported to possess antimicrobial and immunomodulatory properties, they can be tested as an adjuvant treatment along with the antibiotics which are the current standard of care. This study aims to investigate the anti-bacterial and immunomodulatory roles of human bone marrow MSC-derived conditioned medium (MSC-CM) in P. aeruginosa-infected human corneal epithelial cells (HCECs) in vitro. METHODS: The effect of MSC-CM on the growth of clinical isolates of P. aeruginosa was evaluated by colony-forming unit assay. The expression of inflammatory cytokines (IL-6 and TNF-α) and an antimicrobial peptide (Lipocalin 2) in lipopolysaccharide-treated MSCs and HCECs was analyzed through ELISA. Corneal epithelial repair following infection with P. aeruginosa was studied through scratch assay. RESULTS: Compared to control (P. aeruginosa (5*105) incubated in DMEM (1 ml) at 37 °C for 16 h), MSC-CM significantly: i) inhibits the growth of P. aeruginosa (159*109 vs. 104*109 CFU/ml), ii) accelerates corneal epithelial repair following infection with P. aeruginosa (9% vs. 24% closure of the wounded area after 12 h of infection), and iii) downregulates the lipopolysaccharide-induced expression of IL-6, TNF-α and Lipocalin 2 in HCECs. A combination of MSC-CM with an antibiotic, Ciprofloxacin moderately regulated the expression of IL-6, TNF-α, and Lipocalin 2. CONCLUSION: MSC-CM holds promise as an adjunctive therapeutic approach for P. aeruginosa-induced corneal epithelial damage.

A comparison of antimicrobial regimen outcomes and antibiogram development in microbial keratitis: a prospective cohort study in Alexandria, Egypt.

INTRODUCTION: Antimicrobial resistance in microbial keratitis has not been previously explored in Alexandria. We aim to recommend effective therapies through identification of etiological agents, determination of antimicrobial susceptibilities, and comparing outcomes of empiric topical antimicrobials. METHODS: In this 2022 prospective cohort conducted in Alexandria Main University Hospital cornea clinic, antimicrobial susceptibilities of isolated microorganisms from corneal scrapings were detected and antibiograms were developed. Bacterial (BK), fungal (FK), or mixed fungal/bacterial keratitis (MFBK) patients on empiric regimens were compared for ulcer healing, time-to-epithelialization, best-corrected visual acuity, interventions, and complications. RESULTS: The prevalent microorganisms in 93 positive-cultures were coagulase-negative staphylococci (CoNS, 30.1%), Pseudomonas aeruginosa (14%), and Aspergillus spp. (12.9%). CoNS were susceptible to vancomycin (VAN, 100%) and moxifloxacin (MOX, 90.9%). Gram-negative bacteria showed more susceptibility to gatifloxacin (90.9%) than MOX (57.1%), and to gentamicin (GEN, 44.4%) than ceftazidime (CAZ, 11.8%). Methicillin-resistance reached 23.9% among Gram-positive bacteria. Fungi exhibited 10% resistance to voriconazole (VRC). Percentages of healed ulcers in 49 BK patients using GEN + VAN, CAZ + VAN and MOX were 85.7%, 44.4%, and 64.5%, respectively (p = 0.259). Their median time-to-epithelialization reached 21, 30, and 30 days, respectively (log-rank p = 0.020). In 51 FK patients, more ulcers (88.9%) healed with natamycin (NT) + VRC combination compared to VRC (39.1%) or NT (52.6%) (p = 0.036). Their median time-to-epithelialization was 65, 60, and 22 days, respectively (log-rank p < 0.001). The VRC group required more interventions (60.9%) than NT + VRC-treated group (11.1%) (p = 0.018). In 23 MFBK patients, none healed using NT + CAZ + VAN, while 50% healed using VRC + CAZ + VAN (p = 0.052). Regimens had comparable visual outcomes and complications. CONCLUSION: Based on the higher detected susceptibility, we recommend empiric MOX in suspected Gram-positive BK, gatifloxacin in Gram-negative BK, and GEN + VAN in severe BK. Due to better outcomes, we recommend NT + VRC in severe FK. TRIAL REGISTRATION: ClinicalTrials.gov identifier, NCT05655689. Registered December 19, 2022- Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT05655689?cond=NCT05655689.&draw=2&rank=1.

Human tear metabolites associated with nucleoside-signalling pathways in bacterial keratitis.

OBJECTIVE: The study aimed to profile and quantify tear metabolites associated with bacterial keratitis using both untargeted and targeted metabolomic platforms. METHODS: Untargeted metabolomic analysis using liquid-chromatography-Q Exactive-HF mass-spectrometry explored tear metabolites significantly associated with bacterial keratitis (n = 6) compared to healthy participants (n = 6). Differential statistics and principal component analysis determined meaningful metabolite differences between cases and controls. Purines and nucleosides were further quantified and compared between 15 cases and 15 controls in the targeted metabolomic platform using TSQ quantum access triple quadrupole mass spectrometry. Compound quantification was done by plotting the calibration curves and the difference in the compound levels was evaluated using the Wilcoxon rank-sum test. RESULTS: In the untargeted analysis, 49 tear metabolites (27 upregulated and 22 downregulated) were differentially expressed between cases and controls. The untargeted analysis indicated that the purine metabolism pathway was the most affected by bacterial keratitis. Metabolite quantification in the targeted analysis further confirmed the upregulation of xanthine (P = 0.02) and downregulation of adenine (P < 0.0001), adenosine (P < 0.0001) and cytidine (P < 0.0001) in the tears of participants with bacterial keratitis compared to that of healthy participants. CONCLUSIONS: Bacterial keratitis significantly changes the tear metabolite profile, including five major compound classes such as indoles, amino acids, nucleosides, carbohydrates, and steroids. This study also indicates that tear fluids can be used to map the metabolic pathways and uncover metabolic markers associated with bacterial keratitis. Conceivably, the inhibition of nucleoside synthesis may contribute to the pathophysiology of bacterial keratitis because nucleosides are required for maintaining cellular energy homeostasis and immune adaptability.

Bacteria-Targeting Nanosilver-Based Antibacterial Drugs for Efficient Treatment of Drug-Resistant Bacterial-Infected Keratitis.

Keratitis caused by drug-resistant bacteria is a severe condition that can lead to corneal perforation and even blindness, making effective treatment a top priority amid growing antibiotic resistance. Eye drops for anti-inflammatory treatment necessitate frequent administration of high doses throughout every day due to bacterial resistance resulting from antibiotic overuse and the low bioavailability of drugs. To overcome these issues, an antibacterial nanocomposite is prepared via conjugating random copolymers of galactose and 3-(acrylamide)phenylboronic acid to the surface of silver nanoparticles. The customized nanocomposites trigger specific binding to bacteria, resulting in excellent retention of the drug on the ocular surface, resulting in rapid and powerful killing of bacteria and inhibition of bacterial proliferation. Due to its superior drug delivery capabilities to the ocular surface, the functionalized nanocomplex markedly amplifies the anti-inflammatory efficacy, even at low doses. This effect is achieved by impeding immune cell infiltration and diminishing the synthesis of inflammatory mediators and cytokines, thereby suggesting enhanced healing properties for corneal inflammation. This study demonstrates a promising nanocomposite which is an effective and safe antibacterial strategy for bacterial keratitis with favorable prognostic and clinical conversion potential.

Practice patterns in the management of bacterial keratitis: a five-continent survey.

PURPOSE: To assess the current diagnostic and therapeutic practice patterns in early management of bacterial keratitis over five continents. METHODS: Between March and August 2019, we distributed an online survey including two clinical scenarios of bacterial keratitis, namely, a mild case and severe case, to 2936 ophthalmologists from 144 countries around the world. The survey consisted of 29 questions. We performed descriptive statistics and a comparative analysis of the answers according to the participants' continent of practice, practice setting, seniority, and subspecialty. RESULTS: We received 237 surveys from 54 countries (8% response rate). The proportion of respondents performing microbiological investigations was higher in North America, Asia, Europe, and Oceania than Africa and South America (p < 0.05). This ratio was also higher among ocular surface specialists than for other ophthalmologists (p < 0.001). For mild cases, fluoroquinolone monotherapy and a combination of two or more antibiotics were prescribed by 46% and 41% respondents, respectively. For severe cases, fluoroquinolone monotherapy and a combination of antibiotics were prescribed by 20% and 78% respondents, respectively. Fluoroquinolone monotherapy was the most commonly prescribed treatment in South America, Africa, and Oceania. A combination of two antibiotics was preferentially prescribed in the rest of the world. Topical steroids were prescribed in both circumstances, respectively, in 72% and 75% of cases. CONCLUSION: Our results highlight essential geographical disparities in the current management of bacterial keratitis over five continents.

Repeated sessions of PACK-CXL WA for the treatment of resistant bacterial keratitis: a retrospective study.

OBJECTIVE: The aim of this work is to evaluate the safety and efficacy of repeated sessions of photo-activated chromophore for keratitis-cross linking (PACK-CXL) window absorption (WA) for the treatment of resistant bacterial keratitis (BK). PATIENTS AND METHODS: This is a retrospective clinical cohort study. Thirty eyes with clinically suspected and lab-confirmed bacterial keratitis, resistant to appropriate antibiotic therapy- which was modified by sensitivity reports- for 2 weeks with failure of epithelialization for 4 weeks after the standard anti-microbial therapy (SAT) together with one setting of PACK-CXL WA were included. If after the first session of PACK-CXL, there is a start of improvement in the form of reduction of the size of corneal ulcer and stromal infiltrates together with the start of epithelialization on clinical examination and AS-OCT, another session of PACK-CXL WA was performed after one week, and so on, till the complete healing and resolution of bacterial keratitis and confirmation by negative bacterial culture. Identification of the micro-organisms was done by lab study before and after treatment. Corneal healing was evaluated by corneal examination and anterior segment OCT (AS-OCT). RESULTS: Thirty eyes of 30 patients were recruited in this study. They were 16 males and 14 females, their mean age was 44.3 ± 5.38 years. The mean ulcer size was 3.96 ± 1.87 (mm3), while the mean size of stromal infiltrates was 4.52 ± 2.24 (mm3). PACK-CXL WA treatment was performed an average of 2.87 times for the 30 eyes. Complete healing and resolution (Successful treatment) was observed in 27 eyes (90%) of cases and failure of epithelialization was observed only in 3 eyes (10%). Complete corneal healing was reported in the second month postoperatively in 90% of eyes. CONCLUSION AND RECOMMENDATION: PACK-CXL WA may be a promising, non-invasive treatment option for resistant bacterial keratitis. It may have a synergistic effect with standard antimicrobial treatment (SAT). Also, it can overcome the antibiotics resistance that has become rapidly spreading worldwide. Repeated sessions of PACK-CXL WA may be more effective for the treatment of resistant bacterial keratitis till complete epithelialization and resolution of BK than a single session with few complications. However, further prospective and comparative studies to support the results are needed.

Activity of multipurpose contact lens solutions against Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens and Candida albicans biofilms.

INTRODUCTION: The use of contact lenses has progressively increased around the world, thereby increasing the risk of complications. The most serious complication is microbial keratitis (corneal infection) that can progress to a corneal ulcer. METHODS: Fourteen multipurpose contact lens solutions were tested on mature biofilms comprising Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens and Candida albicans, using the minimum disinfection times recommended by the manufacturers. The biofilm was induced in the lens case, and 24 h later, the solutions were added. Activity against planktonic and sessile cells was evaluated and quantified as colony forming units per millilitre. The minimum concentration for biofilm eradication was defined as a 99.9% reduction in viable cells. RESULTS: Although most solutions exhibited activity against planktonic cells, only five of the 14 solutions produced a significant reduction in the S. marcescens biofilm. No solution achieved the minimal biofilm eradication of S. aureus, P. aeruginosa and C. albicans. CONCLUSION: Multipurpose contact lens solutions provide greater bactericidal and/or fungicidal activity on planktonic cells than biofilms. The minimal eradication biofilm concentration was only achieved for S. marcescens.

Betaine- and L-Carnitine-Based Ionic Liquids as Solubilising and Stabilising Agents for the Formulation of Antimicrobial Eye Drops Containing Diacerein.

The therapeutic efficacy of topically administered drugs, however powerful, is largely affected by their bioavailability and, thus, ultimately, on their aqueous solubility and stability. The aim of this study was to evaluate the use of ionic liquids (ILs) as functional excipients to solubilise, stabilise, and prolong the ocular residence time of diacerein (DIA) in eye drop formulations. DIA is a poorly soluble and unstable anthraquinone prodrug, rapidly hydrolysed to rhein (Rhe), for the treatment of osteoarthritis. DIA has recently been evaluated as an antimicrobial agent for bacterial keratitis. Two ILs based on natural zwitterionic compounds were investigated: L-carnitine C6 alkyl ester bromide (Carn6), and betaine C6 alkyl ester bromide (Bet6). The stabilising, solubilising, and mucoadhesive properties of ILs were investigated, as well as their cytotoxicity to the murine fibroblast BALB/3T3 clone A31 cell line. Two IL-DIA-based eye drop formulations were prepared, and their efficacy against both Staphylococcus aureus and Pseudomonas aeruginosa was determined. Finally, the eye drops were administered in vivo on New Zealand albino rabbits, testing their tolerability as well as their elimination and degradation kinetics. Both Bet6 and Carn6 have good potential as functional excipients, showing solubilising, stabilising, mucoadhesive, and antimicrobial properties; their in vitro cytotoxicity and in vivo ocular tolerability pave the way for their future use in ophthalmic applications.

A Pilot Study to Evaluate Genipin in Staphylococcus aureus and Pseudomonas aeruginosa Keratitis Models: Modulation of Pro-Inflammatory Cytokines and Matrix Metalloproteinases.

Infectious keratitis is a vision-threatening microbial infection. The increasing antimicrobial resistance and the fact that severe cases often evolve into corneal perforation necessitate the development of alternative therapeutics for effective medical management. Genipin, a natural crosslinker, was recently shown to exert antimicrobial effects in an ex vivo model of microbial keratitis, highlighting its potential to serve as a novel treatment for infectious keratitis. This study aimed to evaluate the antimicrobial and anti-inflammatory effects of genipin in an in vivo model of Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) keratitis. Clinical scores, confocal microscopy, plate count, and histology were carried out to evaluate the severity of keratitis. To assess the effect of genipin on inflammation, the gene expression of pro- and anti-inflammatory factors, including matrix metalloproteinases (MMPs), were evaluated. Genipin treatment alleviated the severity of bacterial keratitis by reducing bacterial load and repressing neutrophil infiltration. The expression of interleukin 1B (IL1B), interleukin 6 (IL6), interleukin 8 (IL8), interleukin 15 (IL15), tumor necrosis factor-α (TNF-α), and interferon γ (IFNγ), as well as MMP2 and MMP9, were significantly reduced in genipin-treated corneas. Genipin promoted corneal proteolysis and host resistance to S. aureus and P. aeruginosa infection by suppressing inflammatory cell infiltration, regulating inflammatory mediators, and downregulating the expression of MMP2 and MMP9.

A Review of the Categorizations of Mild, Moderate, and Severe Bacterial Keratitis Ulcers and Day-1 Treatment Regimen When Using the Topical Fluoroquinolones 0.3% Ciprofloxacin and 0.3% Ofloxacin.

Background: There are published suggestions that bacterial keratitis (BK) can be classified as mild, moderate, or severe and that the day-1 antibiotic drop regimen may differ for each category using the topical second-generation fluoroquinolones 0.3% ciprofloxacin and 0.3% ofloxacin (2FQ). The classification criteria are not consistently defined and the suggested regimens are often unreferenced and so here, the evidence base for applying such regimens in clinical practice is examined. Objective: To examine the evidence base regarding the categorization criteria used for BK and determine whether any evidence exists to support suggestions that different day-1 treatment regimen using the 2FQ may be applied based on any assigned categorization. Methods: The literature on BK treatment was reviewed, as were the clinical studies involving the commercially available 2FQ. All statements pertaining to classification and treatment paradigms involving BK were then collated and reviewed, as were the methodologies employed in the 2FQ clinical studies. Results: There have been no clinical trials using the 2FQ, or indeed any other topical antibiotics, which have used different day-1 drop regimen depending on the size, depth, and location of the ulcer or for ulcers classified as mild, moderate, or severe. Thus, there is no evidence to support the suggestion that a lower number of drops on day 1 is as effective as a higher number on categorized BK ulcers. Conclusions: No standardized method of categorizing BK was found, and there is no evidence to support the contention that mild, moderate, or smaller BK ulcers should be treated any differently to larger or severe ulcers on day 1. The manufacturers of 2FQ do not supply different treatment regimens for different ulcer sizes and severity categories. When using the 2FQ, all BK ulcers should be treated equally in line with the manufacturers' recommended day-1 treatment regimen.

Clinical comparative analysis of bacterial keratitis according to contact lens use: a retrospective study in a tertiary referral center of South Korea.

PURPOSE: To compare the clinical aspects and treatment outcomes of contact lens-related bacterial keratitis (CLBK) and non-CLBK patients. METHODS: Altogether 217 patients of bacterial keratitis (CLBK; 62, non-CLBK; 155) hospitalized between January 2012 and December 2020 were retrospectively analyzed for epidemiology, microbiological profiles, predisposing factors, clinical characteristics, and treatment outcomes. Poor treatment outcomes (PTO) were defined as a final BCVA < 0.3 (Snellen), a decreased visual acuity after treatment, complications, or surgical intervention. Relative importance of the initial clinical features leading to PTO was assessed using the random forest model and two-proportion Z-test. RESULTS: The most common predisposing factors were sleeping with wearing CL (51.6%) in the CLBK group and trauma (55.5%) in the non-CLBK group. There were significant differences between the two groups in mean age (35.1:55.1 years, p < 0.001), female sex (56.5:34.8%, p = 0.003), symptom duration (6.2:6.9 days, p = 0.019), gram-negative organisms (83.3:48.3%, p = 0.008), epithelial healing time (8.5:14.1 days, p = 0.004), final BCVA (0.15:0.46 logMAR, p = 0.015), and PTO (9.7:21.9%, p = 0.035). For the entire group, the initial BCVA < 0.1 (27.9%), symptom duration ≥ 5 days (19.4%), age ≥ 60 years (16.4%), and hypopyon (14.0%) were important initial clinical features leading to PTO in the random forest model. In CLBK group, the type of CL or CL-related history was not significantly related to PTO. CONCLUSION: CLBK patients had a higher proportion of females, younger age, gram-negative bacteria, and better treatment outcomes than those of non-CLBK patients. There were no significant risk factors leading to PTO in either the type of CL or CL-related history.

The bactericidal effect of two photoactivated chromophore for keratitis-corneal crosslinking protocols (standard vs. accelerated) on bacterial isolates associated with infectious keratitis in companion animals.

BACKGROUND: Bacterial corneal infections are common and potentially blinding diseases in all species. As antibiotic resistance is a growing concern, alternative treatment methods are an important focus of research. Photoactivated chromophore for keratitis-corneal crosslinking (PACK-CXL) is a promising oxygen radical-mediated alternative to antibiotic treatment. The main goal of this study was to assess the anti-bactericidal efficacy on clinical bacterial isolates of the current standard and an accelerated PACK-CXL treatment protocol delivering the same energy dose (5.4 J/cm2). METHODS: Clinical bacterial isolates from 11 dogs, five horses, one cat and one guinea pig were cultured, brought into suspension with 0.1% riboflavin and subsequently irradiated. Irradiation was performed with a 365 nm UVA light source for 30 min at 3mW/cm2 (standard protocol) or for 5 min at 18mW/cm2 (accelerated protocol), respectively. After treatment, the samples were cultured and colony forming units (CFU's) were counted and the weighted average mean of CFU's per µl was calculated. Results were statistically compared between treated and control samples using a linear mixed effects model. RESULTS: Both PACK-CXL protocols demonstrated a significant bactericidal effect on all tested isolates when compared to untreated controls. No efficacy difference between the two PACK-CXL protocols was observed. CONCLUSION: The accelerated PACK-CXL protocol can be recommended for empirical use in the treatment of bacterial corneal infections in veterinary patients while awaiting culture results. This will facilitate immediate treatment, the delivery of higher fluence PACK-CXL treatment within a reasonable time, and minimize the required anesthetic time or even obviate the need for general anesthesia.

Effect of resolvin D1 on experimental bacterial keratitis to prevent corneal scar.

PURPOSE: The study aims to investigate the role of the lipid mediator resolvin D1 (RvD1) in bacterial keratitis in a murine model. METHODS: The effect of RvD1 on Pseudomonas aeruginosa-stimulated human corneal epithelial cells (HCECs) and mouse macrophages and dendritic cells (DCs) was assessed. C57BL/6 mouse corneas were abraded and treated with RvD1 after stimulation with P. aeruginosa, following which cytokine production level in the cornea and drainage lymph nodes was compared with that in controls. Corneal opacity and thickness were assessed using anterior segment photographs, and optical coherence tomography and corneal infiltrates were analyzed using immunohistochemistry for neutrophils. RESULTS: RvD1 significantly inhibited pro-inflammatory cytokine production in HCECs, mouse macrophages, and DCs. Corneal opacity and corneal thickness were reduced, and the development of corneal infiltrates, specifically neutrophils, was also significantly inhibited by RvD1 in response to stimulation with P. aeruginosa. CONCLUSIONS: RvD1 inhibits P. aeruginosa-induced corneal inflammation. This finding supports a potential therapeutic approach for patients with bacterial keratitis.

Infectious keratitis: A review.

Globally, infectious keratitis is the fifth leading cause of blindness. The main predisposing factors include contact lens wear, ocular injury and ocular surface disease. Staphylococcus species, Pseudomonas aeruginosa, Fusarium species, Candida species and Acanthamoeba species are the most common causal organisms. Culture of corneal scrapes is the preferred initial test to identify the culprit organism. Polymerase chain reaction (PCR) tests and in vivo confocal microscopy can complement the diagnosis. Empiric therapy is typically commenced with fluoroquinolones, or fortified antibiotics for bacterial keratitis; topical natamycin for fungal keratitis; and polyhexamethylene biguanide or chlorhexidine for acanthamoeba keratitis. Herpes simplex keratitis is mainly diagnosed clinically; however, PCR can also be used to confirm the initial diagnosis and in atypical cases. Antivirals and topical corticosteroids are indicated depending on the corneal layer infected. Vision impairment, blindness and even loss of the eye can occur with a delay in diagnosis and inappropriate antimicrobial therapy.

Ocular Surface Infection Mediated Molecular Stress Responses: A Review.

Infection mediated ocular surface stress responses are activated as early defense mechanisms in response to host cell damage. Integrated stress responses initiate the host response to different types of infections and modulate the transcription of key genes and translation of proteins. The crosstalk between host and pathogen results in profound alterations in cellular and molecular homeostasis triggering specific stress responses in the infected tissues. The amplitude and variations of such responses are partly responsible for the disease severity and clinical sequelae. Understanding the etiology and pathogenesis of ocular infections is important for early diagnosis and effective treatment. This review considers the molecular status of infection mediated ocular surface stress responses which may shed light on the importance of the host stress-signaling pathways. In this review, we collated literature on the molecular studies of all ocular surface infections and summarize the results from such studies systematically. Identification of important mediators involved in the crosstalk between the stress response and activation of diverse signaling molecules in host ocular surface infection may provide novel molecular targets for maintaining the cellular homeostasis during infection. These targets can be then explored and validated for diagnostic and therapeutic purposes.

Epidemiology, clinical profile and treatment outcomes of bacterial and fungal keratitis.

PURPOSE: The purpose of the study is to determine the microbiological etiology, epidemiological factors, and clinical profile and treatment outcomes of infective keratitis in Ophthalmology department, Minia University, Egypt. METHODS: Prospective, nonrandomized, observational clinical series of cases, including 150 patients with mean age 30 (range 12 to 85 years), 90 patients (60%) were males and 60 (40%) were females, clinically diagnosed as infective corneal ulcer, attending the Ophthalmology Department-Faculty of Medicine. Minia University, Minia, Egypt. From December 2018 to December 2020. Detailed history taking and all clinical findings were collected. Corneal scrapings were obtained from patients and subjected to staining and culture for bacterial and fungal pathogens; Bacterial and fungal growth were identified by standard laboratory procedures. RESULTS: Corneal trauma by a vegetative matter was the commonest risk factor associated with infective keratitis in 92 cases (61.3%). Smear and culture was positive in 83 cases (58.4%) of 142 corneal scrapings obtained, of which 60 cases were fungal (72.3%), 21 cases were bacterial (25.3%) and two cases were mixed bacterial and fungal (2.4%), Aspergillus species was the commonest fungal species isolated in fungal keratitis. One hundred forty-two cases (94.67%) healed completely with scar. Only six cases (4%) required evisceration due to aggressive presentation from the start and keratoplasty was performed for two cases (1.33%). CONCLUSIONS: Fungal keratitis was the commonest type in cases attending to our department. Adequate diagnosis, management and follow-up helped in achieving high successful curative outcomes. CLINICAL TRIAL NUMBER: Clinical Trials.gov ID: NCT04894630. Time of registration 1 December 2018.

Role of surfactant protein-D in ocular bacterial infection.

PURPOSE: Our review explains the role of surfactant protein D (SP-D) in different kinds of bacterial infection based on its presence in different ocular surface tissues. We discuss the potential role of SP-D against invasion by pathogens, with the aim of identifying new prospects for the possible mechanism of SP-D-mediated immune processes, and the diagnosis, prognosis, or treatment of ocular bacterial infection. METHODS: We reviewed articles about the role of SP-D in various ocular bacterial infections or infection-related ocular diseases through PubMed, Google Scholar, and the Web of Science databases. RESULTS: SP-D acts as an important immune factor that can resemble molecules in different polymerization states and that defends against pathogen invasion. The increased SP-D production and secretion in tear fluid and the cornea after ocular bacterial infections such as Staphylococcus aureus, Pseudomonas aeruginosa keratitis, and infection-related ocular diseases, was shown to have potential anti-inflammatory effects. The mechanisms of SP-D's action against ocular bacterial infections include presenting, aggregating, opsonizing, and phagocytizing antigens, as well as regulating anti-bacterial immunity processes, including toll-like receptor-5 (TLR-5) pathway and IL-8 effect, TLR-4 and TLR-2 pathways and other possible ways remained to be elucidated in more detail. The findings demonstrate the potential of SP-D as an important clinical diagnostic biomarker prognosis predictor, and target for ocular immunotherapy. CONCLUSION: SP-D participates in invasion by different ocular bacteria and infection-related ocular diseases through multiple immune mechanisms. This finding provides new prospects for the diagnosis, prognosis and treatment of ocular bacterial infection.

Preparation and in vitro/in vivo evaluations of novel ocular micelle formulations of hesperetin with glycyrrhizin as a nanocarrier.

The purpose of this study was to explore the potential of formulating hesperetin into an ophthalmic solution with dipotassium glycyrrhizinate (DG) as a micelle nanocarrier. A DG-based micelle ophthalmic solution encapsulating hesperetin (DG-Hes) was developed and its in vitro/in vivo characterizations were evaluated. The optimal formulation featured a DG/hesperetin (Hes) weight ratio of 12:1 and an encapsulation efficiency of 90.4 ± 1.7%; The optimized DG-Hes was characterized as small uniform spheres with an average micelle size of 70.93 ± 3.41 nm, a polydispersity index of 0.11 ± 0.02, and an electrically negative surface (-36.12 ± 2.79 mV). The DG-Hes ophthalmic solution had good tolerance in rabbit eyes. DG-Hes significantly improved the in vitro passive permeation, ex vivo corneal permeation, and in vivo ocular bioavailability of Hes. DG-Hes showed markedly increases in in vitro antioxidant activity. In vitro antibacterial activity tests revealed a lower minimum inhibitory concentration and lower minimum bactericidal concentration for DG-Hes ophthalmic solution were lower than for free Hes. DG-Hes ophthalmic solution also significantly reduced symptoms of eye infection in the rabbit bacterial keratitis model when compared to a Hes suspension. These results suggest that DG-Hes eye drops may be useful as a new ophthalmic preparation for the treatment of ocular diseases, especially bacterial ophthalmopathy.

Alterations in the conjunctival surface bacterial microbiome in bacterial keratitis patients.

Microbial keratitis is an infectious disease of the eye, in which the cornea is inflamed. Under severe conditions, keratitis can lead to significant loss of vision and enucleation of the eye. Ocular trauma is the major risk factor causing keratitis and microorganisms viz., bacteria, fungi, viruses are the causative agents. The current study characterized the conjunctival bacterial microbiomes of healthy individuals and individuals with bacterial keratitis (BK) and assessed whether ocular microbiome dysbiosis is prevalent in BK patients. Ocular bacterial microbiomes were generated from the conjunctival swabs of healthy controls (HC-SW) and conjunctival swabs (BK-SW) and corneal scrapings (BK-CR) of BK patients using V3-V4 amplicon sequencing and data analysed using QIIME and R software. The Alpha diversity indices, diversity and abundance of different phyla and genera, heat map analysis, NMDS plots and inferred functional pathway analysis clearly discriminated the bacterial microbiomes of conjunctival swabs of healthy controls from that of BK patients. Preponderance of negative interactions in the hub genera were observed in BK-CR and BK-SW compared to HC-SW. In addition, a consistent increase in the abundance of pathogenic bacteria, as inferred from published literature, was observed in the conjunctiva of BK patients compared to HC and this may be related to causing or exacerbating ocular surface inflammation. This is the first study demonstrating dysbiosis in the ocular bacterial microbiome of conjunctiva of bacterial keratitis patients compared to the eye of healthy controls. The bacterial microbiome associated with the corneal scrapings of keratitis individuals is also described for the first time.