OBJECTIVE

Despite being a preventable and treatable condition, central microbial keratitis (CMK) and its complications remain to be a significant cause of vision loss in our country. This study presents the demographic profile, risk factors, etiologies, treatments, and outcomes of CMK in the Philippines.

The study was a two-center, prospective, non-randomized clinical study involving the patients of the External Disease and Cornea Clinics of two tertiary eye referral centers in the Philippines. It was conducted as the Philippine leg of the Asia Cornea Society Infectious Keratitis Study (ASCIKS).1 Patients with a clinical diagnosis of CMK rendered by a cornea specialist, and who signed the consent form, were recruited into the study. They underwent uniform sample collection and culture techniques as described in the ACSIKS. All patients were followed-up for 6 months. Data collected included demographics, risk factors, culture results, management, and treatment outcomes. Descriptive statistics and frequency were used to analyze the data.

A total of 348 patients diagnosed with CMK were included. Trauma (65.5%) among the middle-aged (42.9 ± 17.9 years) male population was the most significant risk factor for development of CMK, followed by contact lens wear (12.9%), prior ocular surgery (6.0%), and ocular surface diseases (3.4%). Bacterial keratitis (53.2%) was still the most common etiology of CMK, followed by fungal keratitis (27.0%), Acanthamoeba keratitis (5.7%), and viral keratitis (2.0%). Aspergillus species (18.3%) were the most common microbial isolates. Pseudomonas species (13.9%) were the most common bacterial isolates. The median time from onset of symptoms to consultation with the study centers was 2 weeks. Medical treatment was enough to treat the infection in 34.8% of cases. Surgical intervention was necessitated in 22.6% with evisceration/enucleation done in 1 out of 3 patients who had surgery.

Bacterial infection remains the most common cause of CMK in the Philippines, followed by fungal infection. Significant risk factors include trauma and contact lens wear. Aspergillus species and Pseudomonas species were the most common fungal and bacterial isolates, respectively. Despite medical treatment, almost a quarter of the cases still required surgical intervention.

OBJECTIVES

Acanthamoeba spp. are free-living amoebae commonly found in aquatic environments, with pathogenic genotypes capable of causing severe diseases such as acanthamoeba keratitis and granulomatous amoebic encephalitis. Environmental factors, particularly pH, influence their survival and distribution. Tadlac Lake located at Los Baños, Laguna, Philippines is a Class C freshwater body used for aquaculture, recreation, and irrigation. To date, no study has specifically assessed Acanthamoeba colonization in Tadlac Lake.

In this study, detection of the presence of Acanthamoeba spp. and evaluation of pH as a potential factor influencing their persistence in Tadlac Lake was conducted. One-time sampling was conducted from nine sites of the lake. Surface water samples were collected at a depth of 10–20 cm, filtered through 1.2 μm glass microfiber filters, and cultured on non-nutrient agar plates lawned with live Escherichia coli. Plates were incubated at 30°C for 14 days and examined daily under light microscopy, while pH was measured in situ.

Cyst-like structures resembling amoebae were observed, but these did not exhibit definitive Acanthamoeba morphology under light microscopy. No Acanthamoeba spp. were confirmed and the recorded pH levels ranged from 8.72 to 10.51, exceeding the optimal growth range (7.0–9.0) reported for the organism.

Findings of this study suggest alkaline conditions may have inhibited the proliferation and persistence of Acanthamoeba spp. in the lake. These findings highlight pH as a potential limiting factor for Acanthamoeba survival in alkaline freshwater bodies and underscore the importance of integrating physicochemical monitoring into pathogen surveillance frameworks.

Acanthamoeba Keratitis/epidemiology* ; Hospitals ; Humans ; Referral and Consultation ; Retrospective Studies ; Singapore/epidemiology*

Aspergillus fumigatus ; Cytokines ; Humans ; Interleukin-1beta ; Keratitis ; Receptors, IgE ; Tumor Necrosis Factor-alpha ; Tumor Necrosis Factors

Acanthamoeba castellanii has ubiquitous distribution and causes primary acanthamoebic keratitis (AK). AK is a common disease in contact lens wearers and results in permanent visual impairment or blindness. In this study, we observed the cytopathic effect, in vitro cytotoxicity, and secretion pattern of cytokines in human corneal epithelial cells (HCECs) induced by A. castellanii trophozoites and/or cysts. Morphological observation revealed that panked dendritic HCECs co-cultured with amoeba cysts had changed into round shape and gradually died. Such changes were more severe in co-culture with cyst than those of co-cultivation with trophozoites. In vitro cytotoxicity assay revealed the highest cytotoxicity to HCECs in the co-culture system with amoeba cysts. A. castellanii induced the expression of IL-1α, IL-6, IL-8, and CXCL1 in HCECs. Secreted levels of IL-1α, IL-6, and IL-8 in HCECs co-cultured with both trophozoites and cysts were increased at an early incubation time (3 and 6 hr). These results suggested that cytopathic changes and pro-inflammatory cytokines release of HCECs in response to A. castellanii, especially amoebic cysts, are an important mechanism for AK development.
Acanthamoeba castellanii ; Acanthamoeba ; Amoeba ; Blindness ; Coculture Techniques ; Cytokines ; Epithelial Cells ; Humans ; In Vitro Techniques ; Interleukin-6 ; Interleukin-8 ; Keratitis ; Trophozoites ; Vision Disorders

Acanthamoeba, one of free-living amoebae (FLA), remains a high risk of direct contact with this protozoan parasite which is ubiquitous in nature and man-made environment. This pathogenic FLA can cause sight-threatening amoebic keratitis (AK) and fatal granulomatous amoebic encephalitis (GAE) though these cases may not commonly be reported in our clinical settings. Acanthamoeba has been detected from different environmental sources namely; soil, water, hot-spring, swimming pool, air-conditioner, or contact lens storage cases. The identification of Acanthamoeba is based on morphological appearance and molecular techniques using PCR and DNA sequencing for clinico-epidemiological purposes. Recent treatments have long been ineffective against Acanthamoeba cyst, novel anti-Acanthamoeba agents have therefore been extensively investigated. There are efforts to utilize synthetic chemicals, lead compounds from medicinal plant extracts, and animal products to combat Acanthamoeba infection. Applied nanotechnology, an advanced technology, has shown to enhance the anti-Acanthamoeba activity in the encapsulated nanoparticles leading to new therapeutic options. This review attempts to provide an overview of the available data and studies on the occurrence of pathogenic Acanthamoeba among the Association of Southeast Asian Nations (ASEAN) members with the aim of identifying some potential contributing factors such as distribution, demographic profile of the patients, possible source of the parasite, mode of transmission and treatment. Further, this review attempts to provide future direction for prevention and control of the Acanthamoeba infection.
Acanthamoeba ; Amoeba ; Animals ; Asia, Southeastern ; Asian Continental Ancestry Group ; Encephalitis ; Humans ; Keratitis ; Nanoparticles ; Nanotechnology ; Parasites ; Plants, Medicinal ; Polymerase Chain Reaction ; Sequence Analysis, DNA ; Soil ; Swimming Pools ; Water

Acanthamoeba keratitis (AK) is a rare sight-threatening corneal infection, often reporting from contact lens wearers. An asymptomatic human immunodeficiency virus (HIV)-infected Thai male without history of contact lens use complained foreign body sensation at his left eye during motorbike riding. He had neither specific keratitis symptoms nor common drugs responding, which contributed to delayed diagnosis. By corneal re-scraping, Acanthamoeba-like cysts were detected by calcofluor white staining and agar culture. The etiological agent obtained from the culture was molecularly confirmed by Acanthamoeba spp.-specific PCR, followed by DNA sequencing. The results from BLAST and phylogenetic analysis based on the DNA sequences, revealed that the pathogen was Acanthamoeba T4, the major genotype most frequently reported from clinical isolates. The infection was successfully treated with polyhexamethylene biguanide resulting in corneal scar. This appears the first reported AK case from a non-contact lens wearer with HIV infection in Thailand. Although AK is sporadic in developing countries, a role of free-living Acanthamoeba as an opportunistic pathogen should not be neglected. The report would increase awareness of AK, especially in the case presenting unspecific keratitis symptoms without clinical response to empirical antimicrobial therapy.
Acanthamoeba Keratitis ; Acanthamoeba ; Agar ; Asian Continental Ancestry Group ; Base Sequence ; Corneal Injuries ; Delayed Diagnosis ; Developing Countries ; Foreign Bodies ; Genotype ; HIV Infections ; HIV ; Humans ; Keratitis ; Male ; Off-Road Motor Vehicles ; Polymerase Chain Reaction ; Sensation ; Sequence Analysis, DNA ; Thailand

PURPOSE: To analyze clinical aspects in a cohort of patients with Staphylococcus keratitis according to coagulase positivity (coagulase negative Staphylococcus [CNS], coagulase positive Staphylococcus [CPS]). METHODS: Epidemiology, predisposing factors, clinical characteristics, treatment outcomes, and antibiotic susceptibility were comparatively analyzed in 138 cases of culture-proven Staphylococcus keratitis (94 eyes with CNS and 44 eyes with CPS) over 20 years (1998–2017) at Yeungnam University Hospital. Poor clinical outcomes were defined as a final corrected visual acuity <0.1, a decreased visual acuity after treatment, complications, or surgical treatment. Risk factors for poor clinical outcomes were evaluated in the total cohort and analyzed using multivariate logistic regression. RESULTS: The most common predisposing factors were corneal trauma in the CNS group (47.9%) and previous ocular surface disease in the CPS group (31.8%). No significant differences were observed in mean age, sex, previous ocular surface disease, epithelial defect size, and hypopyon between the two groups. Methicillin susceptibility (39.4% vs. 72.7%, p < 0.001) was significantly lower in the CNS group, and poor clinical outcomes (28.0% vs. 43.9%, p = 0.076) were more common in the CPS group. The significant risk factors for poor clinical outcomes were initial best-corrected visual acuity <0.1, epithelial defect size ≥ 5 mm², symptom duration ≥10 days, and hypopyon. CONCLUSIONS: No significant differences were observed in epidemiological factors and initial clinical characteristics between the two study groups, but predisposing factors and methicillin susceptibility differed between the two groups. Treatment outcomes were relatively worse in the CPS group than in the CNS group, but the difference was not statistically significant. Poor clinical outcomes were more associated with long symptom duration and poor initial clinical characteristics than with coagulase positivity.
Causality ; Coagulase ; Cohort Studies ; Corneal Injuries ; Epidemiology ; Humans ; Keratitis ; Logistic Models ; Methicillin ; Risk Factors ; Staphylococcus ; Visual Acuity

PURPOSE: The purpose of this study was to evaluate the clinical aspects of inpatients with bacterial keratitis according to culture positivity. METHODS: This was a retrospective review of 98 cases of inpatients with bacterial keratitis who were treated between January 2011 and December 2016 in Yeungnam University Hospital. Epidemiology, predisposing factors, clinical characteristics, and treatment outcomes were compared between culture positive (CP, 39 eyes) and culture negative (CN, 59 eyes) groups. Risk factors for poor clinical outcome were evaluated in the total cohort and analyzed using multivariate logistic regression. RESULTS: Pseudomonas spp. (31%) and Staphylococcus spp. (24%) were common in the CP group. There were no significant differences in previous ocular surface disease, contact lens wear, or hypopyon between the two groups. Epithelial defect size ≥5 mm² (51%:31%, p = 0.04) and initial visual acuity <0.1 (Snellen) (51%:31%, p = 0.04) were significantly higher in the CP group than in the CN group. Epithelial healing time ≥14 days (18%:5%, p = 0.08) and poor clinical outcome (28%:20%, p = 0.37) were more common in the CP group than in the CN group. Risk factors for poor clinical outcome were previous ocular surface disease (odds ratio [OR] = 11.29, 95% confidence interval [CI] = 2.01–63.41, p = 0.006) and previous ocular surgery (OR = 6.98, 95% CI = 1.51–32.20, p = 0.01). CONCLUSIONS: The CP group showed relatively worse initial clinical characteristics than the CN group. Treatment outcomes were slightly worse in the CP group than in the CN group; however, this difference was not statistically significant. Previous ocular surface disease and previous ocular surgery were associated with poor clinical outcome.
Bacterial Infections ; Causality ; Cohort Studies ; Corneal Ulcer ; Epidemiology ; Humans ; Inpatients ; Keratitis ; Logistic Models ; Pseudomonas ; Retrospective Studies ; Risk Factors ; Staphylococcus ; Visual Acuity

PURPOSE: To report a case of a Corynebacterium macginleyi-infected corneal ulcer of a patient who had been treated for conjunctivitis for more than 3 months. CASE SUMMARY: A 72-year-old female was transferred from a private ophthalmic clinic for evaluation of herpetic keratitis with progressive corneal edema and infiltration in the left eye. She had a history of conjunctival hyperemia and eyeball pain in her left eye 3 months prior to her visit. She was treated with levofloxacin eye drops and acyclovir ointment (Herpesid®, Samil, Co., Ltd. Seoul, Korea). On slit lamp examination, 5.4 × 4.0 mm corneal epithelial defects and stromal infiltrations were observed in the upper to central cornea, and endothelial keratic precipitates were found. Gram positive bacteria were detected on Gram staining and Corynebacterium macginleyi was identified on bacterial cultures from the conjunctiva and cornea. She was treated with topical vancomycin eye drops. After 3 months of treatment, the corneal ulcer was completely resolved, leaving mild superficial opacity on the cornea. CONCLUSIONS: While Corynebacterium macginleyi, normal flora of the conjunctiva, is considered a major causative agent for conjunctivitis and blepharitis, Corynebacterium macginleyi should also be considered a possible cause of slowly progressive keratitis in patients with chronic conjunctivitis.
Acyclovir ; Aged ; Blepharitis ; Conjunctiva ; Conjunctivitis ; Cornea ; Corneal Edema ; Corneal Ulcer ; Corynebacterium ; Female ; Gram-Positive Bacteria ; Humans ; Hyperemia ; Keratitis ; Keratitis, Herpetic ; Levofloxacin ; Ophthalmic Solutions ; Seoul ; Slit Lamp ; Vancomycin