Predicting factors and prediction model for discriminating between fungal infection and bacterial infection in severe microbial keratitis

Far-Ultraviolet C Disinfection Reduces Oxidative Damage to the Cornea Compared to Povidone-Iodine Disinfection

Far-ultraviolet C (far-UVC) light shows promise for pathogen control but its safety and efficacy for corneal disinfection remain unclear. In this study, safe far-UVC dosages were investigated for corneal disinfection and its germicidal performance and oxidative damage potential to 5% povidone-iodine (PVP-I) were compared. Rat corneas were exposed to varying 222 nm far-UVC doses (3-60 mJ/cm2) and assessed for ocular damage, apoptosis, and oxidative stress to determine the safe dose of far-UVC. Far-UVC at 30 mJ/cm2 induced corneal apoptosis and oxidative damage, but 15 mJ/cm2 caused no apoptosis or oxidative damage. At this optimized dose (9 mJ/cm2), far-UVC achieved 90.5% sterilization, exceeding 5% PVP-I (80.8%), with significantly less oxidative damage and cell death in the cornea. In conclusion, our study demonstrates that the use of 5% povidone-iodine (PVP-I) for disinfection results in significant oxidative damage to the corneal tissue. However, a safe dosage of far-UVC light exhibited a promising disinfection effect without causing oxidative damage to the corneal tissue. Far-UVC offers a promising alternative for corneal disinfection but requires careful dosage control (≤30 mJ/cm2) to avoid ocular surface harm.

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.

Debulking corneal biopsy with tectonic amniotic membrane transplantation in refractory clinically presumed fungal keratitis

The treatment of fungal keratitis (FK) is challenging due to the subacute indolent course, and initial misdiagnosis. In this retrospective case series, we highlight both the diagnostic and therapeutic roles of corneal biopsy together with amniotic membrane transplantation (AMT) in patients with refractory clinically presumed FK. Debulking biopsy and tectonic AMT were performed during the initial presentation. Biopsy specimens were sent for KOH smears and cultures. After KOH smears confirmed the presence of fungal elements, topical voriconazole 1% was prescribed for the first 72 h then tailored according to the clinical response and the culture results. The outcome measures were complete resolution of infection and restoration of corneal integrity. Cases associated with culture proven bacterial keratitis were excluded. Twelve cases were included in the study. KOH smears confirmed the presence of fungal growth in all specimens. Cultures grew Aspergillus in 6/12 cases, sensitive to voriconazole (5/6) and amphotericin (3/6); Fusarium (4/12), sensitive to both voriconazole and amphotericin; and no growth in 2/12 cases. Amphotericin 0.15% eye drops were added to the 7 cases with proven sensitivity and to the remaining 2 culture negative cases. Gradual resolution of infection was seen in all cases after 35.6 ± 7.8 days. In FK, a debulking biopsy simultaneously with AMT help decrease the microbial load, suppress the inflammatory process, support the corneal integrity, confirm the presence of fungal pathogen.

Assessment of Direct Costs of Admission Due to Presumed Microbial Keratitis in a Tertiary Referral Hospital in Thailand: A 7-Year Retrospective Study

Objective

To evaluate the direct healthcare cost of admission and examine the effects of cost drivers of treating presumed microbial keratitis (MK) at a tertiary referral hospital.

Design

Retrospective study.

Methods

A total of 741 patients who presented with MK were included. All information regarding costs was collected, and demographic data were employed for risk factor analysis.

Results

The total cost of treating MK over a 7-year period at Rajavithi Hospital was US$14,514,625.04, while the median cost was US$10,840.17 per patient (Q1-3, US$5866.56-24,172.28). The medical professional services were the highest cost category in terms of both total cost of treatment over 7 years and median cost per patient, accounting for US$6,474,718.43 and US$5235.20 (Q1-3, US$2582.79-10,474.24) respectively. In 2020, the total cost of treatment declined, corresponding with fewer hospitalized patients; however, the median cost per patient was the highest of all years, amounting to US$15,089.90 (Q1-3, US$8064.17-29102.50), while the median cost per patient from 2014 to 2019 was US$9969.96 (Q1-3, US$5177.98-21,942.68). Statistical significance was found in the median cost per patient in 2020 compared to the median cost per patient in 2014-2019 (p-value 0.019). Risk factors associated with the more expensive cost of treatment were longer length of stay (LOS); age more than 60 years old; readmission; diabetes mellitus (DM); hypertension; and heart disease.

Conclusion

There were several key factors impacting the direct healthcare costs of severe MK treatment. Medical professional services emerged as the most substantial cost category, while longer hospital stays, older age groups, readmission cases, and comorbidities such as diabetes mellitus, hypertension, and heart disease were all linked to elevated treatment expenses. There were no statistically significant differences in the direct medical expenses during hospitalization associated with treating severe MK, whether the culture results were positive or negative, or regardless of the type of cultured organism utilized.

C-DU(KE) Calculator: A Clinical Tool for Risk Stratification in Infectious Keratitis

PURPOSE

The aim of this study was to identify characteristics of infectious keratitis predictive of poor outcome to develop a web-based predictive calculator.

METHOD

A retrospective chart review was performed at the Duke Eye Center. Two hundred fifteen adult patients with culture-proven infectious keratitis presenting between January 1, 2016, and December 31, 2020, were separated into a derivation set (136 patients, 53 positives; 83 controls) and a temporal validation set (79 patients, 26 positives; 53 controls). The poor outcome group consisted of patients requiring penetrating keratoplasty for visually significant scarring, penetrating keratoplasty for ulcer progression, or evisceration/enucleation for endophthalmitis. Univariable analysis was performed followed by stepwise multivariable logistic regression to obtain a predictive model in the derivation data set. Culture-naïve and postculture models were constructed. Discrimination and calibration were assessed using the area under the curve (AUC) and calibration plots, respectively.

RESULTS

The culture-naïve model consisted of corticosteroid drop use postsymptom onset [Odds Ratio (OR) = 2.3, P = 0.054], decreased vision (OR = 2.4, P = 0.001), and increased ulcer area (OR = 1.017, P = 0.017). The postculture model additionally included fungal keratitis (OR = 5.4, P = 0.006) and elapsed time from symptoms to organism-sensitive therapy (OR = 1.027, P = 0.014). The models were summarized by the acronym C-DU(KE). The AUCs for the culture-naïve model were 0.794 in the derivation set and 0.850 in the validation set. The AUCs for the postculture model were 0.898 in the derivation set and 0.946 in the validation set. Calibration plots indicated goodness of fit in the data sets for both models. The calculator was deployed under the URL: https://duke-eye-calculator.shinyapps.io/Corneal_Ulcers/ .

CONCLUSIONS

The C-DU(KE) calculator permits a data-driven prediction of outcome in infectious keratitis that can supplement clinical judgment.

Utility of investigation for suspected microbial keratitis: a diagnostic accuracy study

PURPOSE

The true disease status of a population with suspected microbial keratitis (MK) cannot be verified. There is not an accurate (gold) reference standard to confirm infection and inter-test comparisons of sensitivity and specificity therefore lead to bias with questionable estimates of test utility. We present an alternative method to report results.

METHODS

We used a decision to treat as the definition for MK. We retrospectively compared the results of corneal culture and polymerase chain reaction (PCR) as these are objective tests available for the three principal groups of pathogens. We then estimated the potential contribution of positive results, either alone or in combination, to support the working diagnosis.

RESULTS

We included 2021 (77.4%) eyes with suspected bacterial keratitis, 365 (14.0%) with suspected acanthamoeba keratitis, and 226 (8.6%) with suspected fungal keratitis, all treated between July 2013 and December 2019. In these groups, there were 51.6% positive culture and 6.5% positive PCR results for bacteria, 19.0% and 40.5% for acanthamoeba, and 28.3% and 15.0% for fungi. Between groups the differences in the proportions of positive results from culture and PCR was statistically significant (P < 0.001). The added benefit of PCR to the result of culture in identifying a potential pathogen was 1.4% for bacteria (P = 0.6292), 24.4% for acanthamoeba (P = 0.0001), and 5.8% for fungi (P = 0.3853).

CONCLUSIONS

For suspected MK a comparison of the test positivity rate is an easily comprehensible outcome measure of test utility.

Development and multi-center validation of machine learning model for early detection of fungal keratitis

BACKGROUND

Fungal keratitis (FK) is a leading cause of corneal blindness in developing countries due to poor clinical recognition and laboratory identification. Here, we aimed to identify the distinct clinical signature of FK and develop a diagnostic model to differentiate FK from other types of infectious keratitis.

METHODS

We reviewed the electronic health records (EHRs) of all patients with suspected infectious keratitis in Beijing Tongren Hospital from January 2011 to December 2021. Twelve clinical signs of slit-lamp images were assessed by Lasso regression analysis and collinear variables were excluded. Three models based on binary logistic regression, random forest classification, and decision tree classification were trained for FK diagnosis and employed for internal validation. Independent external validation of the models was performed in a cohort of 420 patients from seven different ophthalmic centers to evaluate the accuracy, specificity, and sensitivity in real world.

FINDINGS

Three diagnostic models of FK based on binary logistic regression, random forest classification, and decision tree classification were established and internal validation were achieved with the mean AUC of 0.916, 0.920, and 0.859, respectively. The models were well-calibrated by external validation using a prospective cohort including 210 FK and 210 non-FK patients from seven eye centers across China. The diagnostic model with the binary logistic regression algorithm classified the external validation dataset with a sensitivity of 0.907 (0.774, 1.000), specificity 0.899 (0.750, 1.000), accuracy 0.905 (0.805, 1.000), and AUC 0.903 (0.808, 0.998).

INTERPRETATION

Our model enables rapid identification of FK, which will help ophthalmologists to establish a preliminary diagnosis and to improve the diagnostic accuracy in clinic.

FUNDING

The Open Research Fund from the National Key Research and Development Program of China (2021YFC2301000) and the Open Research Fund from Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beijing Tongren Hospital, Beihang University &Capital Medical University (BHTR-KFJJ-202001) supported this study.

Deep Learning for Discrimination Between Fungal Keratitis and Bacterial Keratitis: DeepKeratitis

PURPOSE

Microbial keratitis is an urgent condition in ophthalmology that requires prompt treatment. This study aimed to apply deep learning algorithms for rapidly discriminating between fungal keratitis (FK) and bacterial keratitis (BK).

METHODS

A total of 2167 anterior segment images retrospectively acquired from 194 patients with 128 patients with BK (1388 images, 64.1%) and 66 patients with FK (779 images, 35.9%) were used to develop the model. The images were split into training, validation, and test sets. Three convolutional neural networks consisting of VGG19, ResNet50, and DenseNet121 were trained to classify images. Performance of each model was evaluated using precision (positive predictive value), sensitivity (recall), F1 score (test's accuracy), and area under the precision-recall curve (AUPRC). Ensemble learning was then applied to improve classification performance.

RESULTS

The classification performance in F1 score (95% confident interval) of VGG19, DenseNet121, and RestNet50 was 0.78 (0.72-0.84), 0.71 (0.64-0.78), and 0.68 (0.61-0.75), respectively. VGG19 also demonstrated the highest AUPRC of 0.86 followed by RestNet50 (0.73) and DenseNet (0.60). The ensemble learning could improve performance with the sensitivity and F1 score of 0.77 (0.81-0.83) and 0.83 (0.77-0.89) with an AUPRC of 0.904.

CONCLUSIONS

Convolutional neural network with ensemble learning showed the best performance in discriminating FK from BK compared with single architecture models. Our model can potentially be considered as an adjunctive tool for providing rapid provisional diagnosis in patients with microbial keratitis.

Fungal Keratitis in Northern Thailand: Spectrum of Agents, Risk Factors and Putative Virulence Factors

Fungal keratitis (FK) is a serious ocular infection that can result in various degrees of vision loss, including blindness. The aim of the study was to identify and retrospectively review all FK cases diagnosed between August 2012 and December 2020 at a tertiary care hospital in northern Thailand with a specific focus on epidemiologic features, including season, patient sex and age, the spectrum of pathogens, and presence of certain putative virulence factors. Of 1237 patients with corneal ulcers, 294 (23.8%) were confirmed by direct microscopic examination and/or fungal culture. For the positive cases, direct examinations of Calcofluor white (CW) stains and KOH mounts were found in 97.3% (286/294) and 76.5% (225/294), respectively (p < 0.05). Of the cases diagnosed by microscopy and culture, fungi were isolated in 152 (51.7%), with Fusarium spp. being the most frequently identified (n = 69, 45.5%) followed by dematiaceous fungi (n = 45, 29.6%) and Aspergillus spp. (n = 18, 11.8%). The incidence of FK was higher in the rainy season of July to October. The mean age was 54.4 ± 14.4 (SD) years, with a range of 9–88 years. Males (75.8%) were affected significantly more than females (24.2%) (p < 0.05). Of 294 patients, 132 (44.9%) were middle-aged adults (41–60 years) and 107 (36.4%) were older than 60 years. Trauma to the eye by soil or vegetative matter were the most common preceding factors (188/294; 64.0%). We assessed two virulence factors. First, 142 of the 152 culture-positive FK cases were due to molds, indicating that hyphal morphogenesis is extremely important in disease. We also demonstrated that fungal melanization occurs in the molds during the course of FK by applying a melanin-specific monoclonal antibody (MAb) that labeled fungal elements in corneal samples of patients, and melanin particles derived from the hyphae were also recovered after treatment of the samples with proteolytic enzymes, denaturant and hot concentrated acid. In summary, we demonstrate that northern Thailand has a high rate of FK that is influenced by season and males engaged in outside activities are at highest risk for disease. Moulds are significantly more commonly responsible for FK, in part due to their capacity to form hyphae and melanins. Future studies will examine models of fungal corneal interactions and assess additional factors of virulence, such as secreted enzymes, to more deeply decipher the pathogenesis of FK.

Fungal keratitis at a tertiary eye care in Northern Thailand: Etiology and prognostic factors for treatment outcomes

PURPOSE

To evaluate etiology and prognostic factors for treatment outcomes of fungal keratitis (FK).

METHODS

Culture-positive FK patients between 2012 and 2017 were reviewed. Treatment outcomes were categorized into success (resolved within two weeks), slow response and medication failure (no improvement or required surgery). Etiology and risk factors for poor treatment outcomes were analyzed.

RESULTS

A total of 113 eyes of 113 patients (77% males) were recruited. Ocular trauma (69.0%) was the most common predisposing factor. Of this, 80% were exposed to organic foreign bodies. The most common pathogen was Fusarium spp. (45.2%), while dematiaceous fungi were discovered in 29.6%. Medical treatment was successful in 24.8% of eyes, while 29.2% had a slow response and 42.5% failed medication. Therapeutic keratoplasty was performed in 22.1% of eyes and 11.5% eventually required eye removal. Significant risk factors for medication failure were advanced age (P = 0.005), delayed antifungal treatment (P = 0.038) and large-size lesion (P = 0.003).

CONCLUSIONS

Ocular trauma was the major predisposing factor of FK in the Northern Thailand. Fusarium was the most common identified pathogen. Many cases were refractory to medications and required surgical intervention. Aging, delayed treatment and a large lesion were predictors for poor outcomes.

Contact Lens Use Patterns, Behavior and Knowledge Among University Students in Thailand

Purpose

Little is known about contact lens (CL) use in young generation. This study aimed to investigate the patterns, behavior and knowledge of CL wear and care in Thai university students.

Methods

A cross-sectional study using online questionnaires was conducted during July 2019 to February 2020 in two Rajabhat universities, Bangkok, Thailand. Participant characteristics, CL information, knowledge and behaviors were collected. Factors associated with poor behaviors and CL-related corneal ulcers were analyzed using logistic regression.

Results

Of 493 students participating in the survey, 336 students (66.78%) were current CL users and completed the questionnaires. Mean age was 19.2 ± 1.4 years with female predominance (80.36%). All students wore soft CL with a major replacement schedule of monthly disposable (90.18%). Good CL wear and care behaviors were found in 190 students (56.55%). The most common poor CL behavior and poor CL knowledge were CL overuse (44.64%) and sleeping with lenses (31.85%), respectively. There were no correlations between behaviors and knowledge (r = 0.03). Purchasing lens from internet, wearing experience over one year, and long wear duration (> 12 hours) were significantly associated with poor CL behavior. Male gender and swimming with lens were significantly associated with history of corneal ulcers.

Conclusion

The study pointed out a low compliance of CL wear and care in Thai university students. Good CL practices, awareness of CL-related complications and purchasing place should be carefully informed and regularly stressed to minimize preventable visual damage in young population.

Procedures, Visits, and Procedure Costs in the Management of Microbial Keratitis

PURPOSE

To investigate the burden of procedures, visits, and procedure costs in the management of microbial keratitis (MK).

METHODS

Medical records of patients from an academic hospital outpatient facility between December 2013 and May 2018 were retrospectively reviewed. Patients were included if they were older than the age of 18 years, recruited for study of likely MK, and not concurrently undergoing treatment for other acute eye conditions. For procedural costs, Medicare data for billing were obtained using the Center for Medicare and Medicaid Services Physician Fee Lookup tool.

RESULTS

A total of 68 patients were included for analysis. Patients were on average 51.3 years (SD = 19.5), 55.9% women (n = 38), and 89.7% White (n = 61). Per person, the average number of procedures was 2.9 (SD = 4.2). The average number of visits was 13.9 (SD = 9.2) over an average of 26.9 weeks (SD = 24.3). Age (P < 0.0001), positive Gram stain (P = 0.03), and mixed Gram stain (P = 0.002) were positively associated with the number of procedures. Age (P = 0.0003), fungal keratitis (P = 0.02), and mixed Gram stain (P = 0.01) were positively associated with the number of visits. Race was inversely associated with the number of procedures (P = 0.045) and visits (0.03). Patients with bacterial keratitis were more likely to have amniotic membrane grafts (P = 0.01) and tarsorrhaphies (P = 0.03) than fungal patients. Across all procedures performed for the management of MK, the mean cost per patient was $1788.7 (SD = $3324.62).

CONCLUSIONS

Patients incur many procedural costs and attend many visits during the management of MK. These findings emphasize the importance of patient-provider communication for frequent follow-up care and the potential need to perform procedures for disease management.

Current understanding and therapeutic management of contact lens associated sterile corneal infiltrates and microbial keratitis

Contact lenses are widely prescribed in clinical practice with multiple applications and advantages. However, contact lenses can be associated with various complications which range from innocuous to severe. Clinicians thus not only need to possess the ability to prescribe the most appropriate contact lenses for each individual patient but also be able to recognise and manage any associated complications. This review examines the existing literature on the management of corneal infiltrative events associated with soft contact lenses, including microbial keratitis, particularly in the context of practising in Australia. The definitions and diagnosis of corneal infiltrative events, as well as the current understanding of their aetiologies, will be explored. The various aspects of a successful management will be discussed, including the applications of therapeutic agents such as antimicrobial and anti-inflammatory agents, the role of microbiological investigations, and strategies to improve long-term prognosis. The currently available evidence supporting management options will be presented, highlighting the relative abundance of high-level evidence on management protocols, antimicrobial selection and treatment duration for microbial keratitis; and the relative paucity of studies and trials for sterile corneal infiltrative events, despite this condition being much more commonly encountered in clinical practice.

Predisposing Factors, Clinical Presentations, and Outcomes of Contact Lens-Related Pythium Keratitis

PURPOSE

To describe predisposing factors, clinical presentations, and treatment outcomes of contact lens (CL)-related Pythium keratitis.

METHODS

This was an 11-year retrospective study of CL-related Pythium keratitis conducted from 2009 to 2019. Six eyes of 6 patients were identified. Demographics, predisposing factors, CL history, clinical presentation, diagnostic tests, treatments, and outcomes were reviewed.

RESULTS

Mean age of the patients was 34 years (SD 16.3 years) with equal proportion between male and female patients. Five of 6 patients (83.3%) used soft CL, whereas 1 patient used rigid gas permeable lens. All patients had a history of water contamination (tap water and water from river and sea). Mean duration from the onset was 7.8 days (range 4-14 days). Mean size of the corneal lesion was 3.33 mm (SD 1.31 mm) in width. The typical feature of tentacle-like lesions radiating in a reticular pattern was observed in all patients. Feathery edge (1 eye), satellite lesions (2 eyes), and radial keratoneuritis (2 eyes) were also found. Every patient received therapeutic penetrating keratoplasty because of failed medical treatments. One patient subsequently underwent enucleation. Globe salvage was achieved in 5 patients (83.33%).

CONCLUSIONS

Awareness of the history of water contamination, recognition of specific clinical features of Pythium keratitis, and performing surgical treatment are key for achieving globe salvage in patients with CL-related Pythium keratitis.