Eleven corneal specimens from nine patients with Salzmann's nodular degeneration of the cornea, together with all available clinical information, were collected for this study. The specimens were examined by light and electron microscopy. An antecedent keratitis was diagnosed by history and microscopic findings in every case. The corneal epithelium showed degenerative changes, its thickness varied, and in nodular areas it often consisted of only a single layer of flattened epithelial cells by light microscopy. Bowman's membrane was missing over the nodules, and in this zone there was excessive secretion of a basement membrane-like material. Hyaline degeneration of collagen, cellular debris, and electron-dense hyaline deposits were seen in the collagen of the nodules. The number of fibrocytes in the nodules varied from many that were active to a few that were degenerating. External irritation because of poor epithelial protection was interpreted as a causative factor, although other tissue repair mechanisms may also have played a role.
Kodamaea ohmeri keratitis is an opportunistic pathogen seen in patients who have undergone invasive procedures and immunocompromised state. It has been identified in septicemia patients, resulting in mortality. To the best of our knowledge, we identified the first case of K. ohmeri keratitis following an injury with vegetative material. A 57-year-old woman with underlying, poorly controlled diabetes mellitus was gardening when a tree leaf accidentally poked her in the eye. Two weeks later, the patient presented with right eye pain, redness and progressive blurring of vision due to a traumatised right cornea. Slit-lamp examination showed a small inferior paracentral corneal stromal infiltrate with overlying epithelial defect. A corneal scraping sample yielded K. ohmeri from Analytical Profile Index (API) 20C yeast identification system. She was treated with intensive topical amphotericin B and fluconazole. After 6 weeks of treatment, the keratitis resolved with faint scar tissue, and her visual acuity improved.
Acanthamoeba castellanii is an opportunistic protozoan responsible for serious human infections including Acanthamoeba keratitis and granulomatous amoebic encephalitis. Despite advances in antimicrobial therapy and supportive care, infections due to Acanthamoeba are a major public concern. Current methods of treatment are not fully effective against both the trophozoite and cyst forms of A. castellanii and are often associated with severe adverse effects, host cell cytotoxicity and recurrence of infection. Therefore, there is an urgent need to develop new therapeutic approaches for the treatment and management of Acanthamoebic infections. Repurposing of clinically approved drugs is a viable avenue for exploration and is particularly useful for neglected and rare diseases where there is limited interest by pharmaceutical companies. Nanotechnology-based drug delivery systems offer promising approaches in the biomedical field, particularly in diagnosis and drug delivery. Herein, we conjugated an antihyperglycemic drug, metformin with silver nanoparticles and assessed its anti-acanthamoebic properties. Characterization by ultraviolet-visible spectrophotometry and atomic force microscopy showed successful formation of metformin-coated silver nanoparticles. Amoebicidal and amoebistatic assays revealed that metformin-coated silver nanoparticles reduced the viability and inhibited the growth of A. castellanii significantly more than metformin and silver nanoparticles alone at both 5 and 10 μM after 24 h incubation. Metformin-coated silver nanoparticles also blocked encystation and inhibited the excystation in Acanthamoeba after 72 h incubation. Overall, the conjugation of metformin with silver nanoparticles was found to enhance its antiamoebic effects against A. castellanii. Furthermore, the pretreatment of A. castellanii with metformin and metformin-coated silver nanoparticles for 2 h also reduced the amoebae-mediated host cell cytotoxicity after 24 h incubation from 73% to 10% at 10 μM, indicating that the drug-conjugated silver nanoparticles confer protection to human cells. These findings suggest that metformin-coated silver nanoparticles hold promise in the improved treatment and management of Acanthamoeba infections.
Acanthamoeba is an opportunistic protist pathogen that is responsible for serious human and animal infection. Being one of the most frequently isolated protists from the environment, it is likely that it readily encounters microaerophilic environments. For respiration under anaerobic or low oxygen conditions in several amitochondriate protists, decarboxylation of pyruvate is catalyzed by pyruvate ferredoxin oxidoreductase instead of pyruvate dehydrogenase. In support, Nitazoxanide, an inhibitor of pyruvate ferredoxin oxidoreductase, is effective and non-mutagenic clinically against a range of amitochondriate protists, Giardia intestinalis, Entamoeba histolytica and Trichomonas vaginalis. The overall aim of the present study was to determine in vitro efficacy of Nitazoxanide against Acanthamoeba castellanii. At micromolar concentrations, the findings revealed that Nitazoxanide neither affected A. castellanii growth or viability nor amoeba-mediated host cell monolayer damage in vitro or extracellular proteolytic activities. Similarly, microaerophilic conditions alone had no significant effects. In contrast, microaerophilic conditions together with Nitazoxanide showed amoebicidal effects and inhibited A. castellanii-mediated host cell monolayer damage as well as extracellular proteases. Using encystation assays, it was observed that Nitazoxanide inhibited trophozoite transformation into cysts both under aerophilic and microaerophilic conditions. Furthermore, pre-treatment of cysts with Nitazoxanide inhibited A. castellanii excystation. These findings are important in the identification of potential targets that could be useful against parasite-specific respiration as well as to understand the basic biology of the life cycle of Acanthamoeba.
Amoebae from the genus Acanthamoeba are facultative pathogens of humans and other animals. In humans they most frequently infect the eye causing a sight threatening infection known as Acanthamoeba keratitis (AK), and also cause an often fatal encephalitis (GAE). A mannose-binding protein (MBP) has been identified as being important for Acanthamoeba infection especially in AK. This lectin has previously been characterized from Acanthamoeba castellanii as consisting of multiple 130 kDa subunits. MBP expression correlates with pathogenic potential and is expressed in a number of Acanthamoeba species. Here we report the purification of a similar lectin from Acanthamoeba culbertsoni and the production of a monoclonal antibody to it. The A. culbertsoni MBP was isolated by affinity chromatography using α-D-mannose agarose and has an apparent molecular weight of 83 kDa. The monoclonal antibody is an IgM that is useful in both western blots and immunofluorescence. We expect that this antibody will be useful in the study of the pathology of A. culbertsoni and in its identification in clinical samples.
Purpose: To report a rare case of non-tuberculous mycobacterial (NTM) choroiditis masquerading as choroidal tumour, where the initial diagnosis was masked by keratitis. Casedescription: A 57-year-old heroin chaser with a pre-existing left eye blindness due to past blunt trauma presented with diffuse bacterial keratitis on the same side. Systemic examination revealed multiple non-tender cervical lymphadenopathies. B-scan ultrasonography showed a hyperechoic choroidal mass with surrounding exudative retinal detachment, resembling a choroidal tumour. However, computed tomography (CT) and magnetic resonance imaging (MRI) scan findings were suggestive of inflammatory choroidal changes. Inflammatory markers were significantly raised and infective screening was positive for HIV and Hepatitis C. Tuberculosis workup was normal. In view of intractable pain, evisceration was done and his vitreous humour was sent for polymerase chain reaction (PCR). It was reported to be positive for Mycobacterium Fortuitum. Conclusion: NTM ocular infections are rare, challenging to diagnose, and potentially sight threatening. Early recognition and prompt treatment is life and vision saving.
Purpose To describe the demographics, indications, clinical outcomes and survival rate of penetrating keratoplasty in Malaysian children living in a suburban area, and discuss the literature on paediatric penetrating keratoplasty. Methodology A retrospective review of medical records was performed on children younger than 17 years of age who had undergone penetrating keratoplasty in Hospital Universiti Sains Malaysia from January 2008 to December 2017. We recorded demographic data, presenting visual acuity, indications, final visual acuity, and graft survival at 12 months into the postoperative period. Results Sixteen eyes of 14 children had penetrating keratoplasty. Mean age was 7.8 ± 5.9 years. Both genders were equally affected. The main indications were infective keratitis (56.25%), congenital corneal opacity (18.75%) and trauma (12.50%). There were 62.50% of patients who had a preoperative visual acuity worse than 6/60. Fifty percent had other combined procedures during the surgery, including lens aspiration, peripheral iridectomy, pupilloplasty and glaucoma tube implant. Best corrected visual acuity of 6/12 or better was achieved in 18.75% of patients. A hazy graft was noted in 68.75% of patients, and was attributed to graft rejection, glaucoma and graft failure. There was a statistically significant association between the presence of vascularized cornea, intraocular inflammation and combined surgery with survival rate of the graft at one-year postoperative period (p < 0.05). Conclusions Infective keratitis is the main indication for penetrating keratoplasty in our pediatric patients. Good visual outcome was documented in a small percentage of the patients. Amblyopia and hazy graft were the main barriers to success in this group of patients. Vascularized cornea, inflammation and combined surgery had significantly affected the survival rate of the grafts in our series.
A 42-year-old gentleman presented with left eye pain after accidental contact with Euphorbia lactea sap while gar- dening. At presentation, left eye best-corrected visual acuity (BCVA) was 20/30. Ocular examination revealed left eye conjunctiva congestion and cornea abrasion. Eye symptoms and BCVA deteriorated over 12 hours. Cornea showed diffuse stromal oedema with presence of anterior uveitis. A diagnosis of toxic keratouveitis was made. He was treat- ed with intensive topical steroids, cycloplegics, lubricants, prophylactic antibiotics and oral non-steroidal anti-in- flammatory analgesic. Patient achieved complete resolution two weeks later. We aim to raise awareness among the ophthalmologists to detect and manage these injuries.
A 47-year-old healthy Indonesian gentleman, presented with blurring of vision on the left eye associated with pain
and redness after history of foreign body entering the eye. A general practitioner prescribed him some eye drops;
however, his symptoms worsened. A corneal laceration wound measuring 0.5 x 3.5mm with a large stromal abscess
measuring 9.0 x 5.0mm with flat anterior chamber was seen on the left eye. Emergency corneal T&S revealed a large
descemetocele and cyanoacrylate corneal glue was applied on the area. C&S showed Pseudomonas aeruginosa.
Patient was subsequently undergone penetrating keratoplasty as a definitive measure. This case highlights the rapid
progression of pseudomonas keratitis, presented with a large descemetocele, which can be mistaken as an infected
corneal laceration wound. Corneal cyanoacrylate glueing together with corneal suturing is a viable temporary method
for large descemetoceles awaiting definitive surgery.
A 30-year-old Bangladeshi gentleman presented with history of sand entering his left eye and was diagnosed as having fungal keratitis by private ophthalmologist. He was treated with three doses of conventional subconjunctival amphotericin B injections (1.5 mg of amphotericin B and 1.2 mg of deoxycholate) over the inferior bulbar conjunctiva and topical antibiotics. Subsequently, he developed conjunctival necrosis over the site of injections and there was no clinical improvement of the keratitis. He was then treated with intensive antifungal and antibiotics eye drops. Debridement of epithelial plug was done and he was given intracameral amphotericin B injection. There was gradual improvement observed then with conjunctival epithelialization. The conjunctival tissue was completely healed after three months along with the corneal ulcer. Subconjunctival injection of Amphotericin B (AMB) may be considered as an adjunct therapy in severe fungal keratitis to address the issue of compliance. Close monitoring is needed due to its known complication of scleritis, scleral thinning and conjunctival necrosis. Liposomal AMB which is known to cause less toxicity given via subconjunctival injection in human subjects needs to be further studied.
T4 genotype Acanthamoeba are opportunistic pathogens that cause two types of infections, including vision-threatening Acanthamoeba keratitis (AK) and a fatal brain infection known as granulomatous amoebic encephalitis (GAE). Due to the existence of ineffective treatments against Acanthamoeba, it has become a potential threat to all contact lens users and immunocompromised patients. Metal nanoparticles have been proven to have various antimicrobial properties against bacteria, fungi, and parasites. Previously, different types of cobalt nanoparticles showed some promise as anti-acanthamoebic agents. In this study, the objectives were to synthesize and characterize the size, morphology, and crystalline structure of cobalt phosphate nanoparticles, as well as to determine the effects of different sizes of cobalt metal-based nanoparticles against A. castellanii. Cobalt phosphate octahydrate (CHP), Co3(PO4)2•8H2O, was synthesized by ultrasonication using a horn sonicator, then three different sizes of cobalt phosphates Co3(PO4)2 were produced through calcination of Co3(PO4)2•8H2O at 200 °C, 400 °C and 600 °C (CP2, CP4, CP6). These three types of cobalt phosphate nanoparticles were characterized using a field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analysis. Next, the synthesized nanoparticles were subjected to biological assays to investigate their amoebicidal, amoebistatic, anti-encystation, and anti-excystation effects against A. castellanii, as well as cell cytotoxicity. The overall results showed that 1.30 ± 0.70 µm of CHP microflakes demonstrated the best anti-acanthemoebic effects at 100 µg/mL, followed by 612.50 ± 165.94 nm large CP6 nanograins. However, amongst the three tested cobalt phosphates, Co3(PO4)2, the smaller nanoparticles had stronger antiamoebic effects against A. castellanii. During cell cytotoxicity analysis, CHP exhibited only 15% cytotoxicity against HeLa cells, whereas CP6 caused 46% (the highest) cell cytotoxicity at the highest concentration, respectively. Moreover, the composition and morphology of nanoparticles is suggested to be important in determining their anti-acathamoebic effects. However, the molecular mechanisms of cobalt phosphate nanoparticles are still unidentified. Nevertheless, the results suggested that cobalt phosphate nanoparticles hold potential for development of nanodrugs against Acanthamoeba.
Introduction Pseudomonas aeruginosa is a common cause of microbial keratitis that can cause a significant loss of visual acuity. Antibiotics, including fluoroquinolones and aminoglycosides, are clinically effective against Pseudomonas-induced keratitis, but their effectiveness has been conspicuously reduced as resistant pathogens have become more potent. This study sought to evaluate the clinical and antibacterial effects of tualang honey as an alternative therapeutic agent against Pseudomonas-induced keratitis. Methods We conducted a randomized control trial in which 30 rabbits were injected intrastromally with 1,000 colony-forming units (CFU) of Pseudomonas aeruginosa in the right eye of each rabbit (n = 30). The rabbits were then randomized into three groups of 10 rabbits each. Group A was treated with topical gentamicin 0.3%, group B was treated with topical tualang honey 30%, and group C received both treatments. The specified treatments were administered every two hours from 24 to 48 hours post injection, and subsequently every four hours for six days. Clinical examinations were performed on days one, two, three, five, and seven, and the mean results of slit lamp examinations (SLEs) were documented. On day seven after pseudomonas induction, the rabbits were euthanized and their corneas were harvested to determine the median CFU per cornea. Results There were no statistically significant differences (p > 0.05) in mean SLE scores (p = 0.209) or median CFU values (p = 0.820) between the three groups. Conclusion Topical gentamicin, topical tualang honey, and the combination of the two all showed similar clinical and antimicrobial effects in treating Pseudomonas-induced keratitis in rabbits. These findings should be verified in further studies with larger sample sizes and the addition of a control group.
The pathogenic free-living amoeba, Acanthamoeba castellanii, is responsible for a rare but deadly central nervous system infection, granulomatous amoebic encephalitis and a blinding eye disease called Acanthamoeba keratitis. Currently, a combination of biguanides, amidine, azoles and antibiotics are used to manage these infections; however, the host cell cytotoxicity of these drugs remains a challenge. Furthermore, Acanthamoeba species are capable of transforming to the cyst form to resist chemotherapy. Herein, we have developed a nano drug delivery system based on iron oxide nanoparticles conjugated with isoniazid, which were further loaded with amphotericin B (ISO-NPs-AMP) to cause potent antiamoebic effects against Acanthamoeba castellanii. The IC50 of isoniazid conjugated with magnetic nanoparticles and loaded with amphotericin B was found to be 45 μg/mL against Acanthamoeba castellanii trophozoites and 50 μg/mL against cysts. The results obtained in this study have promising implications in drug discovery as these nanomaterials exhibited high trophicidal and cysticidal effects, as well as limited cytotoxicity against rat and human cells.