Search Results (39)

Objectives: To characterise the bacterial and fungal spectrum of infectious keratitis (IK) in southern China and to evaluate changes in the bacterial profiles and antimicrobial resistance (AMR) over an 8-year period (2017–2024). Methods: This retrospective study included patients with culture-positive IK treated between 2017 and 2024. Corneal scrapings were obtained for microbiological culture and pathogen identification. Antimicrobial susceptibility testing was performed for all bacterial isolates. Microbial distribution and in vitro antibiotic susceptibility were analysed. Results: A total of 2785 microbial isolates were recovered from 2741 patients. Overall, fungal isolates predominated (59.6%), exhibiting a distinct seasonal distribution, with Fusarium (40.2%) and Aspergillus (14.3%) being the most common genera. Among bacterial isolates, Gram-positive organisms were predominant (63.6%). The most frequently identified Gram-positive organisms were coagulase-negative staphylococci (CNS; 34.9%), while Pseudomonas (18.9%) was the most common Gram-negative pathogen. Over the study period, an increase in the proportions of CNS (p < 0.001) and Serratia was observed (p = 0.017), alongside a decline in Pseudomonas (p = 0.009) and Kocuria (p < 0.001). Resistance among Gram-positive isolates increased for penicillin (from 62.3% to 74.4%; p = 0.002) and levofloxacin (from 26.4% to 46.9%; p < 0.001), whereas Gram-negative resistance generally declined. Conclusions: IK in southern China is characterised by persistent fungal predominance and evolving bacterial composition. AMR patterns differ between Gram-positive and Gram-negative organisms, reflecting both shifts in pathogen distribution and species-specific resistance changes, highlighting the importance of continued regional surveillance to guide empirical therapy. Full article

To evaluate the epidemiology of herpetic keratitis over a 15-year period at a tertiary care center in Switzerland, focusing on the relative incidence of herpes simplex virus (HSV)-1, HSV-2, and varicella zoster virus (VZV), gender distribution, and co-infections, we conducted a retrospective single-center analysis of polymerase chain reaction (PCR) assays from corneal and conjunctival scrapings of suspected herpetic keratitis at a tertiary referral hospital. Patient demographics, viral spectra, and microbiological co-infections were assessed. Between 2010 and 2025, we identified 9954 PCR assays from 2892 patients, with 482 samples testing positive for herpesvirus. HSV-1 was the most frequent pathogen (328 of 3358, 9.8%), followed by VZV (143 of 3112, 4.6%), HSV-2 (9 of 3290, 0.27%), and CMV (2 of 194, 1.0%). Triplet testing (simultaneous HSV-1, HSV-2, and VZV-PCR) enabled direct comparisons of relative incidence rates. We found 2913 triplet testing results, with a relative distribution in positive results of 65.4% for HSV-1, 32.5% for VZV, and 2.1% for HSV-2. HSV-1 keratitis had a statistically significant higher incidence in men (58.9%, p = 0.0044), while no sex difference was detected for VZV (47.9%, p = 0.6683), HSV-2 (33.3%, p = 0.5078), or CMV (100%, p = 0.500). Bilateral infections were present in two patients, and co-infections were detected as follows: 8 cases of HSV-1/VZV co-detection, 3 cases of Acanthamoeba, and 15 of fungi. HSV-1 was the overwhelmingly dominant cause of herpetic keratitis at our institution, occurring more than twice as frequently as VZV and vastly outnumbering HSV-2. The statistically significant higher incidence in men in HSV-1 keratitis suggests possible biological or sociodemographic influences, whereas co-infections highlight the complexity of corneal pathology in a referral setting. These findings underscore the importance of multiplex PCR testing for accurate pathogen detection and provide insights into the epidemiologic landscape of herpetic keratitis. Full article

Background/Objectives: Infectious keratitis represents a major ophthalmological emergency and a leading cause of corneal blindness worldwide. Rapid progression, frequent antimicrobial resistance, and poor therapeutic outcomes make genotypic surveillance essential. This study aimed to analyze the distribution of bacterial pathogens involved in infectious keratitis and characterize their resistance mechanisms at the genotypic level, with emphasis on extended-spectrum β-lactamase (ESBL) genes. Methods: Corneal scrapings were collected from patients diagnosed with bacterial keratitis at the County Clinical Emergency Hospital of Craiova. Isolates were identified using standard microbiological techniques, followed by antimicrobial susceptibility testing. Genotypic resistance markers, including tem, shv, and ctx-M gene families, were investigated using PCR-based methods, while phenotypic resistance was investigated using the Vitek2 system. Results: Gram-positive bacteria were the predominant isolates, with coagulase-negative staphylococci and Staphylococcus aureus accounting for most cases. Among Gram-negative pathogens, Pseudomonas aeruginosa and Enterobacteriaceae were frequently detected. Genotypic analysis revealed tem genes in a substantial proportion of ocular isolates, often plasmid-mediated, while shv genes showed low prevalence and ctx-M genes were less frequent. The genetic determinants correlated well with phenotypic resistance expressed by MICs. Conclusions: The study highlights the significant correlation between genotypic markers and resistance phenotypes in bacterial keratitis. Continuous molecular surveillance is essential to guide targeted therapy, prevent therapeutic failure, and improve patient outcomes in infectious keratitis. Full article

Introduction: Purpureocillium lilacinum (formerly Paecilomyces lilacinus) is an emerging, saprophytic fungus known to cause severe, treatment-refractory ocular infections. It is notoriously clinically resistant to several common antifungal agents, including amphotericin B. Risk factors for Purpureocillium lilacinum (P. lilacinum) keratitis include contact lens wear, ocular trauma, and local or systemic immunosuppression. Case Presentation: We describe the clinical course of a 70-year-old male with type 2 diabetes mellitus and a history of long-term soft contact lens use who presented with a right corneal ulcer. Despite initial treatment with topical voriconazole, the infection progressed over two months to involve the entire globe, resulting in intractable endophthalmitis. Microbiological analysis of corneal scrapings identified P. lilacinum, confirmed by MALDI-TOF mass spectrometry and ITS sequencing. Despite the addition of systemic voriconazole, the patient’s condition deteriorated, leading to a painful blind right eye which ultimately needed enucleation. Conclusions: This case highlights the aggressive potential of P. lilacinum in a host with multiple risk factors. It underscores the critical need for a high index of suspicion, rapid and accurate mycological diagnosis, and immediate, aggressive management. The therapeutic challenges, including intrinsic and emerging antifungal resistance, often necessitate early surgical intervention to prevent catastrophic outcomes. Full article

Despite rising global reports of Acanthamoeba keratitis (AK), the incidence of AK in Switzerland remains unknown. This investigator-initiated, retrospective, multicenter study assessed the nationwide incidence of PCR- and/or culture-positive Acanthamoeba results from January 2010 to December 2023. Data were collected from all tertiary care and large ophthalmological facilities in Switzerland, fully anonymized, and aggregated by month and year. We considered all corneal scraping results, whereby the detection method was specific to local standards. We identified 271 PCR- or culture-positive Acanthamoeba cases over 14 years. Applying the population data from the Federal Statistical Office in Switzerland, this corresponds to a mean incidence of 2.29 cases per million people annually. Infections were most common in summer (87 cases, 32.1%), followed by autumn (74 cases, 27.3%), spring (60 cases, 22.1%), and winter (50 cases, 18.5%). We found no significant change in incidence across the investigated period, p = 0.47. This nationwide study reveals a low but stable incidence of AK in Switzerland, in line with other industrialized countries but well below levels reported in tropical or densely populated regions such as India or Egypt. Seasonal variation supports the influence of environmental exposure and underscores the importance of preventive measures during warmer months. Full article

Infectious keratitis (IK), including bacterial, fungal, parasitic, and viral etiologies, continues to represent a significant cause of ocular morbidity in the United States and around the world. Corneal scraping for smears and cultures remains the gold standard in diagnosing IK; however, molecular diagnoses, including metagenomic deep sequencing (MDS), are promising emerging diagnostic tools. Despite recent interest in procedural treatment such as riboflavin photoactivated chromophore corneal collagen cross-linking (PACK-CXL) and Rose Bengal photodynamic antimicrobial therapy (RB-PDAT), medical treatment advances have remained stagnant. Methods: This review highlights IK pathogens obtained from corneal cultures at Bascom Palmer Eye Institute (BPEI) from 2011 to 2021 and provides the current BPEI algorithms for initial management of IK or as a referred clinically worsening patient. The roles of corticosteroid therapy, PACK-CXL, and RB-PDAT for IK are also summarized. Results: A total of 9326 corneal cultures were performed at BPEI between 2011 and 2021, and only 3609 (38.7%) had a positive organism identified, of which bacteria were the most common (83.4%). Fortified vancomycin and tobramycin are recommended as first-line medical therapy for IK patients based on culture sensitivity data for the top Gram-negative (Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. PACK-CXL and RB-PDAT may benefit IK patients with corneal melting and fungal IK, respectively. Conclusions: Drug holidays, minimizing contamination, and optimizing sample order are crucial to maximizing corneal culture positivity. PACK-CXL and RB-PDAT are promising procedural advancements for IK therapy. Full article

Objectives: The aim was to present the complicated diagnostic and therapeutic process of atypical, painless keratitis caused by a cosmopolitan protozoan of the genus Acanthamoeba. Methods: This Case Report describes a medical case involving a 48-year-old woman who occasionally wears soft contact lenses and was referred to our hospital for treatment due to deteriorating visual acuity in her left eye. The diagnostic process included the isolation of amoebae from corneal scrapings and the morphological and molecular identification of the etiological agent of the infection. Results: After examination, painless atypical keratitis was diagnosed, initially considered recurrent herpetic keratitis. However, antiviral treatment did not bring about any improvement. Further observation revealed a dense, central, annular infiltrate on the periphery of the cornea. Despite treatment, the corneal infiltrate did not improve and the patient required therapeutic penetrating keratoplasty. Ultimately, the patient underwent combined surgery: corneal transplantation with cataract phacoemulsification and intraocular lens implantation. The postoperative course was uneventful. Conclusions: Acanthamoeba keratitis should be included in the differential diagnosis of keratitis, even in the absence of its characteristic feature of severe ocular pain, especially in contact lens wearers and patients who have had herpetic keratitis. Infection of the cornea with the Herpes simplex type 1 virus causes nerve degeneration, which probably translates into a painless course of Acanthamoeba castellanii infection. Full article

To determine the incidence, causative organisms, and treatment effectiveness for microbial keratitis (MK) in the Southwest of England. Retrospective analysis of 872 corneal scrapes (January 2018–December 2022). Microbiology results were evaluated for organism growth and antimicrobial sensitivity. Data were divided into two groups for trend analysis (A: 2018–2020, B: 2021–2022). Of the 872 scrapes, 357 (39.6%) were culture positive. Bacteria accounted for 90.2% of cases, followed by viruses (2.8%), fungi (2.5%), mixed bacterial growth (2.5%), and Acanthamoeba (2.0%). The estimated incidence of MK was 9.69/100,000/year. Group B had a significantly higher overall MK incidence, with no change in pathogen distribution. Pseudomonas aeruginosa was the most frequent isolate (69 cases, 19.3%). In vitro sensitivity to fluoroquinolones was 94.4% for Gram-positive and 98.6% for Gram-negative bacteria. All fungal isolates were sensitive to at least one antifungal. Bacterial pathogens dominate MK in the Southwest of England, with over 90% sensitivity to chloramphenicol, fluoroquinolones, and aminoglycosides, indicating low antimicrobial resistance. Fluoroquinolones remain the recommended first-line therapy for MK. Fungal and protozoal keratitis are rare (<3% of cases), supporting bacteria-focused empirical treatment with close monitoring. Full article

Fungal keratitis is a rare yet severe infection of the cornea. Fungal species distribution depends on the climate and socioeconomic status and can show regional variation. This retrospective single-center study was conducted at a tertiary eye care center and the collaborating Institute of Medical Microbiology in Switzerland. On investigating all fungal-positive corneal scrapings and contact lens assessments of patients with keratitis from January 2012 to December 2023, 206 patients were identified, of which 113 (54.9%) were female. The median age was 38 (IQR 29.8, [18–93]), and 154 (74.8%) applied contact lenses. The most commonly found pathogen was Candida spp., followed by Fusarium spp. Molds were 1.8 times more common than yeasts. Linear regression showed no significant increase or decrease in the infection rate over time (p = 0.5). In addition, 10 patients (4.9%) were found to have coinfections with Acanthamoeba, 11 (5.3%) with HSV-1, none with HSV-2, and 4 (1.9%) with VZV. This study provides a long-term overview of fungal-positive corneal scrapings and contact lens specimens of patients with fungal keratitis. Based on our results, coinfections with Acanthamoeba, HSV, and VZV are frequent, especially in patients wearing contact lenses. Thus, wearing contact lenses may facilitate coinfection in fungal keratitis. Full article

Ophthalmologists’ diagnostic and treatment competence in Acanthamoeba keratitis varies widely. This investigator-initiated, retrospective, single-center chart review examined the electronic patient files regarding PCR-positive Acanthamoeba keratitis. We included corneal and contact lens assessments. We further reviewed the patient’s medical history, corneal scraping results regarding viral or fungal co-infections, and the duration from symptom onset to final diagnosis. We identified 59 eyes of 52 patients from February 2010 to February 2023, with 31 of 52 (59.6%) being female patients. The median (IQR, range) patient age was 33 (25.3 to 45.5 [13 to 90]) years, and the mean (SD, range) time to diagnosis after symptom onset was 18 (10.5 to 35 [3 to 70]) days. Overall, 7 of 52 (7.7%) patients displayed a bilateral Acanthamoeba infection, and 48 (92.3%) used contact lenses at symptom onset. Regarding other microbiological co-infections, we found virologic PCR testing in 45 of 52 (86.5%) patients, with 3 (6.7%) positive corneal scrapings. Fungal cultures were performed in 49 of 52 (94.2%) patients, with 5 (10.2%) positive corneal scrapings. The medical treatment success rate was 45/46 (97.8%). This study raises awareness of patient education in contact lens handling and screens for further microbial co-infections in suspected Acanthamoeba cases. Full article

Fungal keratitis is a relatively rare yet severe ocular infection that can lead to profound vision impairment and even permanent vision loss. Rapid and accurate diagnosis plays a crucial role in the effective management of the disease. A patient’s history establishes the initial clinical suspicion since it can provide valuable clues to potential predisposing factors and sources of fungal exposure. Regarding the evaluation of the observed symptoms, they are not exclusive to fungal keratitis, but their timeline can aid in distinguishing fungal keratitis from other conditions. Thorough clinical examination of the affected eye with a slit-lamp microscope guides diagnosis because some clinical features are valuable predictors of fungal keratitis. Definitive diagnosis is established through appropriate microbiological investigations. Direct microscopic examination of corneal scrapings or biopsy specimens can assist in the presumptive diagnosis of fungal keratitis, but culture remains the gold standard for diagnosing fungal keratitis. Advanced molecular techniques such as PCR and MALDI-ToF MS are explored for their rapid and sensitive diagnostic capabilities. Non-invasive techniques like in vivo confocal microscopy (IVCM) and optical coherence tomography (OCT) are useful for real-time imaging. Every diagnostic technique has both advantages and drawbacks. Also, the selection of a diagnostic approach can depend on various factors, including the specific clinical context, the availability of resources, and the proficiency of healthcare personnel. Full article

Background: Beauveria bassiana is a filamentous fungus commonly used as an insecticide that rarely causes keratitis. Methods: Patients affected by Beauveria bassiana keratitis were retrospectively recruited at San Raffaele Hospital (Milan, Italy) between 2020 and 2022. All subjects underwent comprehensive ophthalmic evaluation, including in vivo confocal microscopy (IVCM) and microbiologic examination of corneal scrapings. Beauveria bassiana was identified using 18S rDNA targeted PCR. Results: Four eyes of four patients (51 ± 8.8 years old) were evaluated. The main risk factors were soft contact lens wear (75%) and trauma with vegetative matter (50%). A superficial infiltrate was displayed in the majority of patients. Three cases (75%) showed hyphae on IVCM. All patients showed clinical improvement after topical antifungal therapy, although mostly through a combination of two antifungals (75%). One patient with a deeper infection required a systemic antifungal agent after one month of topical therapy. All cases required debridement to reduce the microbial load and enhance drug penetration. All patients experienced keratitis resolution following medical treatment (average: 3.3 months). Conclusions: The identification of risk factors and the early diagnosis of Beauveria bassiana keratitis are fundamental in order to avoid its penetration in the deeper corneal stromal layers. Topical antifungal drugs, possibly accompanied by ulcer debridement, may be a successful treatment if instilled from the early phases of the disease. Full article

Infectious keratitis (IK) is among the top five leading causes of blindness globally. Early diagnosis is needed to guide appropriate therapy to avoid complications such as vision impairment and blindness. Slit lamp microscopy and culture of corneal scrapes are key to diagnosing IK. Slit lamp photography was transformed when digital cameras and smartphones were invented. The digital camera or smartphone camera sensor’s resolution, the resolution of the slit lamp and the focal length of the smartphone camera system are key to a high-quality slit lamp image. Alternative diagnostic tools include imaging, such as optical coherence tomography (OCT) and in vivo confocal microscopy (IVCM). OCT’s advantage is its ability to accurately determine the depth and extent of the corneal ulceration, infiltrates and haze, therefore characterizing the severity and progression of the infection. However, OCT is not a preferred choice in the diagnostic tool package for infectious keratitis. Rather, IVCM is a great aid in the diagnosis of fungal and Acanthamoeba keratitis with overall sensitivities of 66–74% and 80–100% and specificity of 78–100% and 84–100%, respectively. Recently, deep learning (DL) models have been shown to be promising aids for the diagnosis of IK via image recognition. Most of the studies that have developed DL models to diagnose the different types of IK have utilised slit lamp photographs. Some studies have used extremely efficient single convolutional neural network algorithms to train their models, and others used ensemble approaches with variable results. Limitations of DL models include the need for large image datasets to train the models, the difficulty in finding special features of the different types of IK, the imbalance of training models, the lack of image protocols and misclassification bias, which need to be overcome to apply these models into real-world settings. Newer artificial intelligence technology that generates synthetic data, such as generative adversarial networks, may assist in overcoming some of these limitations of CNN models. Full article

Acanthamoeba keratitis (AK) is a painful and sight-threatening parasitic corneal infection. In recent years, the incidence of AK has increased. Timely and accurate diagnosis is crucial during the management of AK, as delayed diagnosis often results in poor clinical outcomes. Currently, AK diagnosis is primarily achieved through a combination of clinical suspicion, microbiological investigations and corneal imaging. Historically, corneal scraping for microbiological culture has been considered to be the gold standard. Despite its technical ease, accessibility and cost-effectiveness, the long diagnostic turnaround time and variably low sensitivity of microbiological culture limit its use as a sole diagnostic test for AK in clinical practice. In this review, we aim to provide a comprehensive overview of the diagnostic modalities that are currently used to diagnose AK, including microscopy with staining, culture, corneal biopsy, in vivo confocal microscopy, polymerase chain reaction and anterior segment optical coherence tomography. We also highlight emerging techniques, such as next-generation sequencing and artificial intelligence-assisted models, which have the potential to transform the diagnostic landscape of AK. Full article

Fusarium is a large fungal genus that is widely distributed in the environment, mostly known for its plant pathogenicity. Rarely, it is involved in human pathology, where the type of infection caused is highly dependent upon the portal of entry and the immune status of the host. The study at hand aims to summarize routine methods used in diagnosing such infections as well as more advanced molecular diagnostic methods, techniques that can play a huge role in differentiating between colonization and infection when trying to decide the therapeutic outcome. Consequently, to further support our findings, two different strains (one isolated from corneal scrapings and one isolated from purulent discharge) were analyzed in a clinical context and thoroughly tested using classical and modern diagnostic methods: identification by macroscopical and microscopical examinations of the culture and mass spectrometry, completed by molecular methods such as PCR for trichothecene and ERIC-PCR for genetic fingerprinting. Isolation of a clinically relevant Fusarium spp. from a sample still remains a diagnostic challenge for both the clinician and the microbiologist, because differentiating between colonization and infection is very strenuous, but can make a difference in the treatment that is administered to the patient. Full article