Infectious Keratitis Research Articles

Estimated direct and indirect health care costs of severe infectious keratitis by cultured organisms in Thailand: An 8-year retrospective study.

To evaluate the economic impact of treating severe infectious keratitis (IK) at one tertiary referral center in Thailand by analyzing the direct costs of treatment and estimating the indirect costs, and to determine whether cultured organisms had any effect on treatment expenditure. A retrospective study was conducted of patients with severe IK who had been hospitalized between January 2014 and December 2021 in Rajavithi Hospital. Data from medical records were collected from the time of the patients' admission until the point at which they were discharged and treated in the outpatient department and their IK was completely healed, or until evisceration/enucleation was performed. The direct costs of treatment included fees for services, medical professionals and investigation, as well as for operative and non-operative treatment. The indirect costs consisted of patients' loss of wages, and costs of travel and food. A total of 335 patients were studied. The median direct, indirect and total costs were US$65.2, range US$ 6.5-1,119.1, US$314.5, range US$50.8-1,067.5, and US$426.1, range 57.5-1,971.5 respectively. There was no statistically significant difference between direct, indirect, or total treatment costs for culture-negative and culture-positive patients. Among those who were positive, fungal infections entailed the highest total cost of treatment, and this difference was statistically significant (p<0.001). In terms of direct and indirect costs, patients with fungal infections had the greatest direct costs, and this figure was statistically significant (p = 0.001); however, those with parasitic infections had the highest indirect treatment costs, and this was also statistically significant (p<0.001). Severe IK can cause serious vision impairment or blindness. Indirect costs represented the majority of the expense at 73.8%. There was no difference between direct, indirect, and total treatment costs for patients who were culture-negative or positive. Among the latter, fungal infections resulted in the highest total cost of treatment.

Artificial intelligence in cornea and ocular surface diseases

In modern ophthalmology, the advent of artificial intelligence (AI) is gradually showing promising results. The application of complex algorithms to machine and deep learning has the potential to improve the diagnosis of various corneal and ocular surface diseases, customize the treatment, and enhance patient outcomes. Moreover, the use of AI can ameliorate the efficiency of the health-care system by providing more accurate results, reducing the workload of ophthalmologists, allowing the analysis of a big amount of data, and reducing the time and resources required for manual image acquisition and analysis. In this article, we reviewed the most important and recently published applications of AI in the field of cornea and ocular surface diseases, with a particular focus on keratoconus, infectious keratitis, corneal transplants, and the use of in vivo confocal microscopy.

Amniotic Membrane Transplantation in the Management of Corneal Ulceration Following Infectious Keratitis

ABSTRACT Purpose To report on the outcomes of amniotic membrane transplantation (AMT) for corneal ulceration following infectious keratitis. Method In this retrospective cohort study of 654 patients with culture-proven infectious keratitis from 8 hospitals in Galicia (Spain), a total of 43 eyes of 43 patients (6.6%) underwent AMT for postinfectious corneal ulceration. The indications for AMT were sterile persistent epithelial defects, severe corneal thinning or perforation. Results AMT was successful in 62.8% of cases, with 37.2% requiring an additional surgery. Median time to healing was 40.0 days (IQR 24.2–101.7 days) and final BCVA was lower than baseline (p = 0.001). Ulcers were large (>3 mm) in 55.8% of cases. Previous herpetic keratitis and topical steroid use were more common in patients who received AMT (p < 0.001). 49 microorganisms (43 bacteria and 6 fungi) were isolated. Conclusions AMT is a therapeutic option for complications following infectious keratitis, which present with a sterile persistent epithelial defect, significant corneal thinning or perforation.

Topical formulations containing Trichilia catigua extract as therapeutic options for a genital and an acyclovir-resistant strain of herpes recurrent infection.

Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) infect, respectively, 67% and 13% of the world population, most commonly causing mild symptoms, such as blisters/ulcers. However, severe conditions such as keratitis, encephalitis, and systemic infections may occur, generally associated with the patient's immunological condition. Although Acyclovir® (ACV) and its analogs are the reference drugs for herpetic infections, the number of ACV-resistant HSV infections is growing exponentially. Therefore, new natural products' bioactive compounds have been studied to develop novel effective anti-herpetics. Trichilia catigua is a plant widely used in traditional medicine, including the treatment of skin diseases and sexual infections. In our study, 16 extracts from the bark of T. catigua, obtained with different solvents and their combinations, were evaluated against HSV-1 AR and HSV-2, respectively, ACV resistance and genital strains in vitro. The extracts with the highest selectivity index were used to prepare new topical anti-herpetic formulations and confirmed in vivo. Two new topical formulations were suggested to treat cutaneous and genital herpetic recurrent lesions. The cytotoxicity and antiviral activity were tested using the MTT method. The cytotoxic (CC50) and inhibitory (IC50) concentrations of 50% and the selectivity index (SI: CC50/IC50) were determined. Tc12, Tc13, and Tc16 were added to the formulations. Infected BALB/c mice were treated for 8days, and the severity of the herpetic lesions was analyzed daily. All CEs showed a CC50 value ranging from 143 to 400µg/mL, except for Tc3 and Tc10. Tc12, Tc13, and Tc16 showed the best SI in the 0h, virucidal, and adsorption inhibition assays. In the in vivotest against HSV-1 AR, the infected animals treated with creams were statistically different from the infected non-treated animals and similar to ACV-treated mice. In HSV-2-infected genitalia, similar effects were found for Tc13 and Tc16 gels. The present study demonstrated that extracts from the bark of T. catigua, traditionally used in folk medicine, are a valuable source of active compounds with anti-herpetic activity. The extracts showed a virucidal mechanism of action and prevented the initial stages of viral replication. The cutaneous and genital infections were strongly inhibited by the Tc12, Tc13, and Tc16 extracts. New topical therapeutic alternatives using Trichilia catigua extracts are suggested for patients infected with ACV-resistant strains of HSV.

Validation of the C-DU(KE) Calculator as a Predictor of Outcomes in Patients Enrolled in Steroids for Corneal Ulcer and Mycotic Ulcer Treatment Trials.

The aim of this study was to validate the C-DU(KE) calculator as a predictor of treatment outcomes on a data set derived from patients with culture-positive ulcers. C-DU(KE) criteria were compiled from a data set consisting of 1063 cases of infectious keratitis from the Steroids for Corneal Ulcer Trial (SCUT) and Mycotic Ulcer Treatment Trial (MUTT) studies. These criteria include corticosteroid use after symptoms, visual acuity, ulcer area, fungal etiology, and elapsed time to organism-sensitive therapy. Univariate analysis was performed followed by multivariable logistic regressions on culture-exclusive and culture-inclusive models to assess for associations between the variables and outcome. The predictive probability of treatment failure, defined as the need for surgical intervention, was calculated for each study participant. Discrimination was assessed using the area under the curve for each model. Overall, 17.9% of SCUT/MUTT participants required surgical intervention. Univariate analysis showed that decreased visual acuity, larger ulcer area, and fungal etiology had a significant association with failed medical management. The other 2 criteria did not. In the culture-exclusive model, 2 of 3 criteria, decreased vision [odds ratio (OR) = 3.13, P < 0.001] and increased ulcer area (OR = 1.03, P < 0.001), affected outcomes. In the culture-inclusive model, 3 of 5 criteria, decreased vision (OR = 4.9, P < 0.001), ulcer area (OR = 1.02, P < 0.001), and fungal etiology (OR = 9.8, P < 0.001), affected results. The area under the curves were 0.784 for the culture-exclusive model and 0.846 for the culture-inclusive model which were comparable to the original study. The C-DU(KE) calculator is generalizable to a study population from large international studies primarily taking place in India. These results support its use as a risk stratification tool assisting ophthalmologists in patient management.

Clinical Features, Risk Factors, and Management of Candida Keratitis

ABSTRACT Background/Aims To determine the clinical features, predisposing factors, and management of infectious keratitis caused by Candida spp. Methods Retrospective chart review. Results The medical records of 52 patients (54 eyes) with Candida keratitis were available for statistical analysis. Thinning of the corneal stroma was identified in 34 eyes (63.0%), and corneal perforation occurred in 16 eyes (29.6%). Corneal thinning and perforation were more common in Candida albicans compared with non-albicans (P-val < .001, P = .09, respectively). The most common predisposing factors for Candida keratitis were topical steroid use (21 patients, 40.4%), previous corneal transplantation (17 patients, 32.7%), and preexisting ocular surface disease (15 patients, 28.8%). Fourteen eyes (25.9%) required cyanoacrylate glue application and 10 eyes (18.5%) underwent therapeutic penetrating keratoplasty (TPK). Conclusion Local immunosuppression and ocular surface disease play an important role in Candida keratitis. C. albicans appears to be more invasive compared with non-albicans spp.

Collagen cross-linking as monotherapy in experimentally induced corneal abscess in rabbits

Background and purposeCollagen cross-linking (CXL) has evolved as an essential therapeutic approach for corneal infections, allowing for rapidly eliminating the infecting microorganism while reducing inflammation. This study aims to evaluate the efficacy of CXL as a monotherapy for managing infectious keratitis caused by Fusarium solani and Pseudomonas aeruginosa.Materials and methodsForty-eight white New Zealand rabbits weighing approximately 1.5–2 KG were included. The cornea of one eye of each rabbit was inoculated with either Fusarium solani or Pseudomonas aeruginosa. Group A served as a control and was subdivided into two subgroups, A1 and A2; each subgroup consisted of 8 eyes and was injected with either Fusarium solani or Pseudomonas aeruginosa, respectively. Group B (16 eyes) was inoculated with Fusarium solani, while group C (16 eyes) were inoculated with Pseudomonas aeruginosa. All animals in Group B and C received CXL treatment one week after inoculation of the organisms and after corneal abscess formation was confirmed. At the same time, animals in Group A were left untreated.ResultsThere was a statistically significant reduction in the number of colony-forming units (CFU) in Group B following CXL. No growth existed in any samples at the end of the 4th week. There was a statistically significant difference in the number of CFU between group B and the control group (p < 0.001). In group C, there was a statistically significant reduction in the CFU at the end of the first week after CXL. However, there was regrowth in all samples afterward. All 16 models in Group C showed uncountable and extensive growth during the subsequent follow-ups. There was no statistically significant difference between the number of CFU in Group C and the control group. Histopathology showed lesser corneal melting in CXL-treated Pseudomonas aeruginosa.ConclusionsCollagen cross-linking is promising monotherapy and alternative treatment in managing infective keratitis caused by Fusarium solani but is less effective in Pseudomonas aeruginosa as monotherapy.

Diabetes Exacerbates Pseudomonas aeruginosa Keratitis in Streptozotocin-Induced and db/db Mice via Altering Programmed Cell Death Pathways.

Patients with diabetes have a higher incidence of infections, which are often more severe. This study aimed to investigate the impact of hyperglycemia on bacterial keratitis caused by Pseudomonas aeruginosa (Pa) in two mouse models of diabetes, streptozotocin-induced type 1 diabetes mellitus (T1DM) and db/db type 2 diabetes mellitus. The susceptibility of corneas to Pa was assessed by determining the inocula required to cause infectious keratitis. Dead or dying cells were identified using TUNEL staining or immunohistochemistry. Specific inhibitors were used to evaluate the role of cell death modulators in Pa keratitis. Cytokines and Treml4 expressions were analyzed using quantitative PCR, and the role of Treml4 in keratitis was determined using small interfering RNA technology. DM corneas required significantly fewer inocula to develop Pa keratitis, with T1DM corneas requiring 750 inocula and type 2 diabetes mellitus corneas requiring 2000 inocula, compared with 10,000 inocula required for normal (NL) mice. T1DM corneas had more TUNEL-positive and fewer F4/80-positive cells than NL corneas. Phospho-caspase 8 (apoptosis) and -RIPK3 (necroptosis) staining was more intense in the epithelial and stromal layers of NL and T1DM corneas, respectively. Pa keratitis was augmented by targeting caspase-8 and prevented by RIPK3 inhibition in both NL and T1DM mice. Hyperglycemia suppressed IL-17A/F and augmented IL-17C, IL-1β, IL-1Ra, and TREML4, the downregulation of which protected T1DM corneas from Pa infection by suppressing necroptosis. RIPK3 inhibition blocked Pa infection in db/+ mice and significantly decreased the severity of keratitis in db/db mice. Hyperglycemia exacerbates bacterial keratitis in B6 mice by skewing apoptosis toward necroptosis. Preventing or reversing this transition may serve as an adjunct therapy for treating microbial keratitis in patients with diabetes.

Interpretable deep learning for diagnosis of fungal and acanthamoeba keratitis using in vivo confocal microscopy images

Infectious keratitis refers to a group of corneal disorders in which corneal tissues suffer inflammation and damage caused by pathogenic infections. Among these disorders, fungal keratitis (FK) and acanthamoeba keratitis (AK) are particularly severe and can cause permanent blindness if not diagnosed early and accurately. In Vivo Confocal Microscopy (IVCM) allows for imaging of different corneal layers and provides an important tool for an early and accurate diagnosis. In this paper, we introduce the IVCM-Keratitis dataset, which comprises of a total of 4001 sample images of AK and FK, as well as non-specific keratitis (NSK) and healthy corneas classes. We use this dataset to develop multiple deep-learning models based on Convolutional Neural Networks (CNNs) to provide automated assistance in enhancing the diagnostic accuracy of confocal microscopy in infectious keratitis. Densenet161 had the best performance among these models, with an accuracy, precision, recall, and F1 score of 93.55%, 92.52%, 94.77%, and 96.93%, respectively. Our study highlights the potential of deep learning models to provide automated diagnostic assistance for infectious keratitis via confocal microscopy images, particularly in the early detection of AK and FK. The proposed model can provide valuable support to both experienced and inexperienced eye-care practitioners in confocal microscopy image analysis, by suggesting the most likely diagnosis. We further demonstrate that these models can highlight the areas of infection in the IVCM images and explain the reasons behind their diagnosis by utilizing saliency maps, a technique used in eXplainable Artificial Intelligence (XAI) to interpret these models.

A knowledge-enhanced transform-based multimodal classifier for microbial keratitis identification

Microbial keratitis, a nonviral corneal infection caused by bacteria, fungi, and protozoa, is an urgent condition in ophthalmology requiring prompt treatment in order to prevent severe complications of corneal perforation and vision loss. It is difficult to distinguish between bacterial and fungal keratitis from image unimodal alone, as the characteristics of the sample images themselves are very close. Therefore, this study aims to develop a new deep learning model called knowledge-enhanced transform-based multimodal classifier that exploited the potential of slit-lamp images along with treatment texts to identify bacterial keratitis (BK) and fungal keratitis (FK). The model performance was evaluated in terms of the accuracy, specificity, sensitivity and the area under the curve (AUC). 704 images from 352 patients were divided into training, validation and testing set. In the testing set, our model reached the best accuracy was 93%, sensitivity was 0.97(95% CI [0.84,1]), specificity was 0.92(95% CI [0.76,0.98]) and AUC was 0.94(95% CI [0.92,0.96]), exceeding the benchmark accuracy of 0.86. The diagnostic average accuracies of BK ranged from 81 to 92%, respectively and those for FK were 89–97%. It is the first study to focus on the influence of disease changes and medication interventions on infectious keratitis and our model outperformed the benchmark models and reaching the state-of-the-art performance.

Commentary: Microbial keratitis and antibiotic sensitivity patterns in Central India.

The current issue of the Indian Journal of Ophthalmology (IJO) features an interesting article[1] on fungal predominance and increasing antibiotic resistance patterns in microbial keratitis occurring in central rural India. Microbial keratitis is a major cause of corneal blindness, especially in agriculture-based economies. The causative organisms vary in geographical areas and the antibiotic sensitivity patterns also differ.[2] It is important to be aware of the common causative agents and their response to antibiotics in one’s place of practice. It may not be possible to have access to a microbiologist who has experience in processing small samples that are sent by ophthalmologists. We collected (unpublished) data on microbial keratitis in a microbiology laboratory in the northern part of India, especially in Delhi and the adjoining national capital region, for over three years from 2016 to 2019 (pre-COVID era). All samples were sent by various private practitioners and institutions to the microbiology laboratory. Cultures were inoculated from corneal scrapings of patients with infective keratitis by cornea specialists and sent to a microbiologist (NS) with a specialization in ocular microbiology. There were 466 bacterial isolates. Three hundred twenty-nine (70.6%) bacterial isolates were gram-positive cocci (GPC). Sensitivity patterns to the first line of treatment for GPCs were as follows: cefazoline (225 isolates, 68.3%), ciprofloxacin (203 isolates, 61.7%), ceftazidime (129 isolates, 39.2%), moxifloxacin (282 isolates, 85.7%), amikacin (295 isolates, 89.6%), amoxiclav (162 isolates, 49.2%), amoxicillin (198 isolates, 60.18%), chloramphenicol (236 isolates, 71.%), gatifloxacin (202 isolates, 61.3%), tobramycin (286 isolates, 86%), and vancomycin (285 isolates, 86.6%). Sensitivity patterns to the first line of treatment in gram-negative isolates (total 137) were amikacin (68 isolates, 49.27%), ciprofloxacin (95 isolates, 69.3%), gatifloxacin (41 isolates, 29.9%), moxifloxacin (79 isolates, 57.6%), tobramycin (91 isolates, 66.4%), and doxycycline (61 isolates, 44.5%). Sensitivity patterns to the second line of treatment included imipenem (60 isolates, 43.7%), piperacillin-tazobactam (73 isolates, 53.3%), colistin (72 isolates, 52.5%), and meropenem (68 isolates, 49.6%). Among gram-positive isolates, the most common organisms were coagulase-negative Staphylococcus followed by diphtheroids, Bacillus species, Streptococcus pneumoniae, alpha-hemolytic Streptococcus, and, rarely, Staphylococcus aureus. Among gram-negative organisms, the most common was Pseudomonas aeruginosa followed by other Pseudomonas species, Neisseria species, and very few Acinetobacter and Moraxella. In a study by Das et al.[3] published in the Indian Journal of Ophthalmology, 3981 corneal scrapings were processed in over eight years. Pathogens grew in culture in 1914 samples (48.1%). Bacteria grew in 60% of isolates. The most common gram-positive bacteria were Streptococcus pneumoniae (217/1125, 19.3%) and Staphylococcus aureus (185/1125, 16.4%). Amongst the gram-negative bacteria, Pseudomonas species (99/219, 45.2%) was the most common. In a Korean study by Mun et al.,[4] a 10-year analysis of the microbiological profile and sensitivity of bacterial keratitis was done. Bacteria were isolated in 101 out of 129 samples (78.3%). Coagulase-negative staphylococci (CNS) (15.9%), Staphylococcus aureus (12.1%), and Pseudomonas aeruginosa (10.3%) were the most common isolates. All gram-positive isolates were sensitive to vancomycin, but methicillin resistance was found in 29.4% of CNS and 15.4% of Staphylococcus aureus. All gram-negative isolates were susceptible to ceftazidime and carbapenem, and 11.5%, 3.3%, and 2.8% of gram-negative isolates were resistant to gentamicin, tobramycin, and amikacin, respectively. Ciprofloxacin resistance was observed in 10.3% of gram-positive isolates and 8.8% of gram-negative isolates. Yin et al.[5] evaluated tigecycline susceptibility testing of carbapenem-resistant Klebsiella pneumoniae and Acinetobacter baumannii.[5] They compared the broth microdilution method (BMD), VITEK, and the modified Kirby–Bauer method. No major difference was found. The Kirby–Bauer method is simple, cheap, conventional, and accurate. Rapid identification methods (MALDITOF) have been introduced.[6] They are fast and identify proteins of pathogens, and we get the sensitivity and identification on the same day. The disadvantage is that it is not endowed with standardized protocols. It is expensive and maintenance cost is high. Comparison of culture and sensitivity patterns in different geographical areas may show similarities or, in some instances, several variabilities.[2,7,8] Fluoroquinolones are easily available and can treat infections caused by gram-positive and -negative organisms. They do not need fortification and reconstitution. But resistance to every generation of fluoroquinolones has developed over the years. It is important to know and document resistance patterns which keep changing now and then. The general ophthalmologist needs to be up-to-date on the most likely organisms in their geographical areas and the sensitivity patterns of those organisms so that infections can be controlled in their initial phases. The study published in IJO from central India has a small sample size but concurs with other Indian studies on the larger percentage of fungal infections compared to bacterial keratitis.[3,7] One important caveat is that the patterns can vary in the same geographical area in different periods and that it is the responsibility of the specialists in that area to continue updating the data.

Microbial keratitis and antibiotic sensitivity patterns: A retrospective analysis at a tertiary center in Central India.

To report on the microbiological profile and antibiotic sensitivity patterns of infectious keratitis at a tertiary center in central India. The suspected case of severe keratitis underwent microbiological culture and identification using the VITEK 2 technique. Antibiotic susceptibility for different sensitivity and resistance patterns was analyzed. Demographics, clinical profile, and socioeconomic history was also documented. Culture was positive in 233/455 (51.2%) patients. Pure bacterial growth was present in 83 (35.62%) patients and pure fungus was present in 146 (62.66%) patients. The most common bacterial cause of infectious keratitis was Pseudomonas followed by Staphylococcus and Bacillus. Pseudomonas showed 65%-75% resistance against levofloxacin, ceftazidime, imipenem, gentamycin, ciprofloxacin, and amikacin. Staphylococcus showed 65%-70% resistance against levofloxacin, erythromycin, and ciprofloxacin, with Streptococcus being 100% resistant to erythromycin. This study highlights the current trend of microbiological profiles of infectious keratitis and their antibiotic susceptibility at a rural setup in central India. Fungal predominance and increased resistance against the commonly used antibiotics were noted.

In Situ Hybridization of Polymeric Curcumin to Arginine-Derived Carbon Quantum Dots for Synergistic Treatment of Bacterial Infections.

Effective infectious keratitis treatment must eliminate the pathogen, reduce the inflammatory response, and prevent persistent damage to the cornea. Infectious keratitis is generally treated with broad-spectrum antibiotics; however, they have the risk of causing corneal epithelial cell damage and drug resistance. In this study, we prepared a nanocomposite (Arg-CQDs/pCur) from arginine (Arg)-derived carbon quantum dots (Arg-CQDs) and polymeric curcumin (pCur). Partial carbonization of arginine hydrochloride in the solid state by mild pyrolysis resulted in the formation of CQDs, which exhibited enhanced antibacterial activity. pCur was formed by the polymerization of curcumin, and further crosslinking reduced its cytotoxicity and improved antioxidative, anti-inflammatory, and pro-proliferative activities. The pCur in situ conjugated with Arg-CQDs to form the Arg-CQDs/pCur nanocomposite, which showed a minimum inhibitory concentration of ca. 10 μg mL-1, which was >100-fold and >15-fold lower than that of the precursor arginine and curcumin, respectively, against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The Arg-CQDs/pCur nanocomposite with combined antibacterial, antioxidative, anti-inflammatory, pro-proliferative properties, and long-term retention on cornea enabled synergistic treatment of bacterial keratitis. In a rat model, it can effectively treat P. aeruginosa-induced bacterial keratitis at a concentration 4000-fold lower than the commercially used drug, Sulmezole eye drops. Arg-CQDs/pCur nanocomposites have great potential for application in antibacterial and anti-inflammatory nanoformulations for clinical use to treat infectious diseases.

Mo-based Mo2Ti2C3 MXene as photothermal nanoagents to eradicating methicillin-resistant Staphylococcus aureus with photothermal therapy

Over the last decades, two-dimensional (2D) materials have progressively yielded great outcomes sparking intense research owing to their unique configuration and physicochemical properties. Their current research has effectively been channeled for biomedical purposes. Among them is the largest family, 2D transitional metal carbides (MXenes). In this context, Mo2Ti2C3 (MTC) a form of MXenes with excellent photo-conversion capacity was fabricated and its rising popularity due to its potential for possible treatment of infectious diseases was probed. We demonstrated that MTC MXene's potentiality for the conversion of the photo to heat showed better efficacy in inhibiting the growth of methicillin-resistant Staphylococcus aureus (MRSA). MTC under laser treatment completely killed MRSA, a combined treatment that caused an irreversible antibacterial effect. Also, MTC impeded bacteria-associated infections by completely killing MRSA in an infected wound, preventing tissue proliferation, angiogenesis, and tissue inflammations, demonstrating good biocompatibility, a sure prospect for clinical translation. Furthermore, the collaborative work of the MTC and the local hyperthermia significantly ameliorated MRSA-induced subcutaneous infection and bacterial keratitis, preserving the structural wholeness and transparency of the infected cornea. This study suggests that MTC may serve as a potential platform to augment near-infrared (NIR) therapeutic eradication of bacteria actively and precisely.

Molecular identification of Acanthamoeba spp., Balamuthia mandrillaris and Naegleria fowleri in soil samples using quantitative real-time PCR assay in Turkey; Hidden danger in the soil!

Acanthamoeba spp., Balamuthia mandrillaris, and Naegleria fowleri are pathogenic free-living amoeba (FLA) and are commonly found in the environment, particularly soil. This pathogenic FLA causes central nervous system-affecting granulomatous amebic encephalitis (GAE) or primary amebic meningoencephalitis (PAM) and can also cause keratitis and skin infections. In the present study, we aimed to determine the quantitative concentration of Acanthamoeba spp., B. mandrillaris, and N. fowleri in soil samples collected from places where human contact is high by using a qPCR assay in Izmir, Turkey. A total of 45.71% (n = 16) of Acanthamoeba spp., 20% (n = 7) of B. mandrillaris, and 17.4% (n = 6) of N. fowleri were detected in five different soil sources by the qPCR assay. The quantitative concentration of Acanthamoeba spp., B. mandrillaris, and N. fowleri in various soil sources was calculated at 10 × 105 - 6 × 102, 47 × 104 to 39 × 103, and 9 × 103 – 8 × 102 plasmid copies/gr, respectively. While the highest quantitative concentration of Acanthamoeba spp. and B. mandrillaris was determined in garden soil samples, N. fowleri was detected in potting soil samples. Three different genotypes T2 (18.75%), T4 (56.25%), and T5 (25%) were identified from Acanthamoeba-positive soil samples. Acanthamoeba T4 genotype was the most frequently detected genotype from soil samples and is also the most common genotype to cause infection in humans and animals. To the best of our knowledge, the present study is the first study to identify genotype T5 in soil samples from Turkey. In conclusion, people and especially children should be aware of the hidden danger in the garden and potting soil samples that come into contact most frequently. Public health awareness should be raised about human infections that may be encountered due to contact with the soil. Public health specialists should raise awareness about this hidden danger in soil.

Deep learning-based classification system of bacterial keratitis and fungal keratitis using anterior segment images.

Infectious keratitis is a vision threatening disease. Bacterial and fungal keratitis are often confused in the early stages, so right diagnosis and optimized treatment for causative organisms is crucial. Antibacterial and antifungal medications are completely different, and the prognosis for fungal keratitis is even much worse. Since the identification of microorganisms takes a long time, empirical treatment must be started according to the appearance of the lesion before an accurate diagnosis. Thus, we developed an automated deep learning (DL) based diagnostic system of bacterial and fungal keratitis based on the anterior segment photographs using two proposed modules, Lesion Guiding Module (LGM) and Mask Adjusting Module (MAM). We used 684 anterior segment photographs from 107 patients confirmed as bacterial or fungal keratitis by corneal scraping culture. Both broad- and slit-beam images were included in the analysis. We set baseline classifier as ResNet-50. The LGM was designed to learn the location information of lesions annotated by ophthalmologists and the slit-beam MAM was applied to extract the correct feature points from two different images (broad- and slit-beam) during the training phase. Our algorithm was then externally validated using 98 images from Google image search and ophthalmology textbooks. A total of 594 images from 88 patients were used for training, and 90 images from 19 patients were used for test. Compared to the diagnostic accuracy of baseline network ResNet-50, the proposed method with LGM and MAM showed significantly higher accuracy (81.1 vs. 87.8%). We further observed that the model achieved significant improvement on diagnostic performance using open-source dataset (64.2 vs. 71.4%). LGM and MAM module showed positive effect on an ablation study. This study demonstrated that the potential of a novel DL based diagnostic algorithm for bacterial and fungal keratitis using two types of anterior segment photographs. The proposed network containing LGM and slit-beam MAM is robust in improving the diagnostic accuracy and overcoming the limitations of small training data and multi type of images.

Monitoring trends in antimicrobial susceptibility patterns of bacterial isolates from horses with ulcerative keratitis

SummaryBackgroundUlcerative bacterial keratitis can result in loss of vision or the eye. Antimicrobial susceptibility data are essential in selecting optimal therapy while pending culture results.ObjectivesTo document aerobic bacterial isolates and antimicrobial susceptibilities from horses with ulcerative keratitis and report susceptibility patterns compared to previously described data from the same hospital.Study designRetrospective clinical case series.MethodsMedical records from horses with positive bacterial cultures and a clinical diagnosis of infectious ulcerative keratitis at the University of Tennessee Veterinary Medical Center between March 2011 and December 2020 were reviewed and compared to previously published data from January 1993 to May 2004.ResultsThirty‐one bacterial isolates were cultured from 27 samples (26 horses). The most common bacterial genera were Streptococcus (35%), Staphylococcus (29%) and Pseudomonas (13%), with a shift towards more Staphylococcus and less Streptococcus compared to previous years. There were minimal temporal changes in susceptibilities for these three genera. Staphylococcus spp. were statistically more likely to be cultured than other bacteria after the use of topical neomycin‐polymyxinB‐dexamethasone (p = 0.008). In vitro antimicrobial susceptibility results suggest that targeted combination therapy covered a greater percentage of isolates, compared with monotherapy, but in vitro results may not mirror in vivo results.Main limitationsInconsistencies in available medical data, selection bias and a small sample size are inherent limitations in this retrospective study, along with the inability to test against all available ophthalmic medications, challenges of interpreting cultures with limited veterinary susceptibility data and no susceptibility guidelines for topical medications.ConclusionLimited changes have occurred over the past several decades in corneal bacterial isolates and susceptibilities within this equine ophthalmology referral population, with a shift in more Staphylococcus cultured over time. Monitoring temporal trends of bacterial isolates and antimicrobial susceptibility data is important in every hospital.

Assessing the Impact of Image Quality on Deep Learning Classification of Infectious Keratitis

To investigate the impact of corneal photograph quality on convolutional neural network (CNN) predictions. A CNN trained to classify bacterial and fungal keratitis was evaluated using photographs of ulcers labeled according to 5 corneal image quality parameters: eccentric gaze direction, abnormal eyelid position, over/under-exposure, inadequate focus, and malpositioned light reflection. All eligible subjects with culture and stain-proven bacterial and/or fungal ulcers presenting to Aravind Eye Hospital in Madurai, India, between January 1, 2021 and December 31, 2021. Convolutional neural network classification performance was compared for each quality parameter, and gradient class activation heatmaps were generated to visualize regions of highest influence on CNN predictions. Area under the receiver operating characteristic and precision recall curves were calculated to quantify model performance. Bootstrapped confidence intervals were used for statistical comparisons. Logistic loss was calculated to measure individual prediction accuracy. Individual presence of either light reflection or eyelids obscuring the corneal surface was associated with significantly higher CNN performance. No other quality parameter significantly influenced CNN performance. Qualitative review of gradient class activation heatmaps generally revealed the infiltrate as having the highest diagnostic relevance. The CNN demonstrated expert-level performance regardless of image quality. Future studies may investigate use of smartphone cameras and image sets with greater variance in image quality to further explore the influence of these parameters on model performance. Proprietary or commercial disclosure may be found after the references.

Association of Serious Adverse Effects With the Contamination of Ocular Medications—A Global Perspective

This Viewpoint offers examples of the causes of infectious keratitis around the world and emphasizes the need for vigilance among ophthalmologists to reduce the risk of sight-threatening complications.

Risk Factor of Cataract Formation after Penetrating Keratoplasty

Introduction: Post-corneal graft cataract is a not negligible complication. Its occurrence rate varies from 0.4% (2) to 32% (3) according to series, it can present itself in the form of nuclear, cortical and posterior capsular opacities. Its treatment corresponds to a usual cataract surgery by phacoemulsification with implantation in the capsular bag. Our work aims to identify and analyze the risk factors for the development of cataract after keratoplasty. Materials and Methods: This is an analytical study conducted within the Ophthalmology Service B at the Rabat Specialty Hospital on 58 patients who underwent penetrating keratoplasty. The main criteria studied were: age; sex; indication for surgery and average dose of corticosteroids. Statistical calculations were made using the SPSS 10.0 software for Windows. A p value &lt;0.05 was considered significant. The average follow-up was 24 months. Results: Cataract after corneal transplantation was observed in 10 cases (17.2%). The mean age at the time of cataract diagnosis was 55 years, with extremes ranging from 40 to 70 years? It developed in 7 of the 33 female cases (21%), and in 3 of the 25 male cases (12%). The onset delay ranged between 16 and 24 months, with a mean delay of 18 months after the penetrating keratoplasty. The most frequent type was nuclear cataract (8 of 10 eyes, 80%), posterior subcapsular cataract developed in one eye (10%) and cortical-nuclear cataract in one eye (10%). It developed in 4 of the 9 cases operated for corneal dystrophies (44.4%), in 3 of the 11 cases operated for sequelae of infectious keratitis (27.2%), in 2 of the 13 cases operated for posttraumatic opacity (15%) and in 1 of the 20 cases operated for keratoconus (5%). In our study, only age and operative indication of the graft were considered as risk factors for the development of cataract after corneal transplantation (p&lt;0.05). The preoperative visual acuity, the patient’s sex.