Alternaria is an Infrequent Cause of Keratitis: A Case Report and Review of the Literature

Establishment of a corneal ulcer prognostic model based on machine learning

Corneal infection is a major public health concern worldwide and the most common cause of unilateral corneal blindness. Toxic effects of different microorganisms, such as bacteria and fungi, worsen keratitis leading to corneal perforation even with optimal drug treatment. The cornea forms the main refractive surface of the eye. Diseases affecting the cornea can cause severe visual impairment. Therefore, it is crucial to analyze the risk of corneal perforation and visual impairment in corneal ulcer patients for making early treatment strategies. The modeling of a fully automated prognostic model system was performed in two parts. In the first part, the dataset contained 4973 slit lamp images of corneal ulcer patients in three centers. A deep learning model was developed and tested for segmenting and classifying five lesions (corneal ulcer, corneal scar, hypopyon, corneal descementocele, and corneal neovascularization) in the eyes of corneal ulcer patients. Further, hierarchical quantification was carried out based on policy rules. In the second part, the dataset included clinical data (name, gender, age, best corrected visual acuity, and type of corneal ulcer) of 240 patients with corneal ulcers and respective 1010 slit lamp images under two light sources (natural light and cobalt blue light). The slit lamp images were then quantified hierarchically according to the policy rules developed in the first part of the modeling. Combining the above clinical data, the features were used to build the final prognostic model system for corneal ulcer perforation outcome and visual impairment using machine learning algorithms such as XGBoost, LightGBM. The ROC curve area (AUC value) evaluated the model's performance. For segmentation of the five lesions, the accuracy rates of hypopyon, descemetocele, corneal ulcer under blue light, and corneal neovascularization were 96.86, 91.64, 90.51, and 93.97, respectively. For the corneal scar lesion classification, the accuracy rate of the final model was 69.76. The XGBoost model performed the best in predicting the 1-month prognosis of patients, with an AUC of 0.81 (95% CI 0.63-1.00) for ulcer perforation and an AUC of 0.77 (95% CI 0.63-0.91) for visual impairment. In predicting the 3-month prognosis of patients, the XGBoost model received the best AUC of 0.97 (95% CI 0.92-1.00) for ulcer perforation, while the LightGBM model achieved the best performance with an AUC of 0.98 (95% CI 0.94-1.00) for visual impairment.

Immune Mechanisms of Filamentous Fungal Keratitis

Filamentous fungal keratitis is a particularly serious eye infection that often results in ulceration, corneal perforation, and blindness. The cornea acts as a natural barrier against harmful agents due to the close connection of its epithelial cells. In addition, on its surface, there is a large number of substances with anti-inflammatory and bactericidal properties, such as secretory IgA and mucin glycoproteins, and antimicrobial peptides (AMPs), such as human β-defensin 2 (HBD-2) and LL-37, which are especially increased in filamentous fungal keratitis. The interaction between pathogenic fungi and the host's immune mechanisms is a complex process: pathogen-associated molecular pattern (PAMP) molecules (chitin, β-glucan, and mannan) found in the fungal cell wall are recognized by pattern recognition receptors (PRRs) (toll-like receptors {TLRs}, C-type lectin receptors {CLRs}, nucleotide-binding oligomerization domain-like receptors {NLRs}, and scavenger receptors {SR}) found in host defense cells, triggering the secretion of various types of cytokines, such as interleukins (IL), tumor necrosis factors (TNFs), and chemokines, which recruit macrophages and neutrophils to migrate to the site of infection and activate inflammatory responses. In addition, the interaction of hyphae and corneal epithelial cells can activate cluster of differentiation (CD) 4+ T cells, CD8+ T cells, and B cells and induce secretion of T-helper (Th)-type cytokines 2 (IL-4 and IL-13) and IgG.

Alternaria fungus growing on top of cyanoacrylate glue in a patient with perforated corneal ulcer

Purpose

To demonstrate a case where Alternaria fungus grew on top of cyanoacrylate glue used to seal a perforated corneal ulcer.

Observations

We document the clinical course of a rare case of Alternaria keratitis over the course of 6 months. Despite the purported antifungal properties of cyanoacrylate glue demonstrated in vitro, this case provides in vivo evidence that this substance can serve as a scaffold on which pathogenic fungi may grow.

Conclusion

This report demonstrates the importance of close follow up of patients with corneal glue patches in place. Ophthalmologists should continue to inspect the cornea and glue for possible development of secondary infection, particularly with concomitant contact lens and/or steroid use.

Filamentous Fungal Keratitis in Greece: A 16-Year Nationwide Multicenter Survey

In a multicenter, prospective study of filamentous fungal keratitis in Greece, predisposing factors, etiology, treatment practices, and outcome, were determined. Corneal scrapings were collected from patients with clinical suspicion of fungal keratitis, and demographic and clinical data were recorded. Fungal identification was based on morphology, molecular methods, and matrix assisted laser desorption ionization time-of-flight mass-spectrometry. A total of 35 cases were identified in a 16-year study period. Female to male ratio was 1:1.7 and median age 48 years. Corneal injury by plant material, and soft contact lens use were the main risk factors (42.8% and 31.4%, respectively). Trauma was the leading risk factor for men (68.1%), contact lens use (61.5%) for women. Fusarium species were isolated more frequently (n = 21, 61.8%). F. solani was mostly associated with trauma, F. verticillioides and F. proliferatum with soft contact lens use. Other fungi were: Purpureocillium lilacinum (14.7%), Alternaria (11.8%), Aspergillus (8.8%), and Phoma foliaceiphila, Beauveria bassiana and Curvularia spicifera, one case each. Amphotericin B and voriconazole MIC₅₀s against Fusarium were 2 mg/L and 4 mg/L respectively. Antifungal therapy consisted mainly of voriconazole locally or both locally and systemically, alone or in combination with liposomal AmB. Cure/improvement rate with antifungal therapy alone was 52%, keratoplasty was required in 40% of cases, and enucleation in 8%. In conclusion, filamentous fungal keratitis in Greece is rare, but with considerable morbidity. A large proportion of cases resulted in keratoplasty despite appropriate antifungal treatment.Kindly confirm the given name and family name are correctly identified for all authros.ConfirmedJournal instruction requires a city and country for affiliations; however, these are missing in affiliations 1, 3, 4, 5, 6, 13. Please verify if the provided city and country are correct and amend if necessary.All provided cities and countries are correct.

Predictive Factors for Resolution of Dematiaceous Fungal Keratitis

PURPOSE

To ascertain the clinicomicrobiological correlation and evaluate the prognostic factors associated with medical resolution in cases of Curvularia, Alternaria, and Scedosporium keratitis.

METHODS

A retrospective review of clinical and microbiological records of culture-proven cases of Curvularia, Alternaria, and Scedosporium keratitis from 2017 to 2019 was performed. Multivariate logistic regression analyses were performed to assess the predictive factors for medical resolution.

RESULTS

There were a total of 79 eyes of 79 patients. Among these, there were 56 (70.8%), 15 (18.9%), and 8 (10.1%) patients with Curvularia, Scedosporium, and Alternaria keratitis, respectively. Clinical resolution with medical treatment was achieved in 46 of 56 (82.1%) patients with Curvularia keratitis, 8 of 15 (53.3%) patients with Scedosporium, and 7 of 8 (87.5%) patients with Alternaria keratitis. In comparison between Curvularia and Scedosporium, macroscopic pigmentation [18/56 (32.1%)] of anterior stromal plaque-like infiltrate [20/56 (35.7%)] was clinically more in cases with Curvularia, whereas larger diameter of the infiltrate, P = 0.002, posterior stromal infiltrate (40%), P = 0.03, and hypopyon, P = 0.009, were more common with Scedosporium. Multivariate logistic regression analysis, by backward elimination, showed that maximum dimension of the infiltrate (P = 0.01; odds ratio = 0.52, 95% confidence interval, 0.31-0.86) and presence of a hypopyon (P = 0.02; odds ratio = 0.12, 95% confidence interval, 0.02-0.71) were significant factors that were not favoring medical resolution.

CONCLUSIONS

Larger size of the infiltrate, posterior stromal involvement, and presence of a hypopyon are poor prognostic indicators among all 3 species. Variation in species is not a predictor of clinical resolution.

Recent advances on mycotic keratitis caused by dematiaceous hyphomycetes

Dematiaceous hyphomycetes (DH) are darkly pigmented fungi ubiquitously found all over the world as plant pathogens and saprophytes, and many of the members of this group have emerged as opportunistic pathogens. These fungi are responsible for a wide variety of infections including mycotic keratitis, which is considered as one of the major causes of corneal blindness, particularly in tropical and subtropical countries with an annual global burden of about 1 000 000 patients. The infection is more common in workers working in an outdoor environment. Moreover, trauma is found to be the most important predisposing cause of mycotic keratitis. Considerable delay in diagnosis and scarcity of effective pharmacological drugs are the major factors responsible for increased morbidity and visual impairment. Considering the crucial role of DH in mycotic keratitis, in the present review, we have focused on major DH with special emphasis on their pathogenicity, diagnosis and treatment strategies.

Enhancement in serum (1-3)-β-D-glucan level by cutaneous alternariosis: A case report and literature review

Contamination with the fungus Alternaria spp. is often considered to have originated from laboratory sources, which occasionally causes infection in immunocompromised patients, termed as phaeohyphomycosis. Here, we have reported a case of cutaneous alternariosis caused by Alternaria alternata. This diagnosis was based on microscopic examination and mycological culturing of patient's vesicular lesions, with the use of 5 molecular markers (namely, ITS, ATPase, Actin, rpb2, and tef1) for strain identification. We noted that Alternaria infection caused an increase in the serum level of (1-3)-β-D-glucan (BG) in the patients. To the best of our knowledge, no such finding has been reported in previously in the literature.

Infectious Keratitis Caused by Rare and Emerging Micro-Organisms

PURPOSE

To provide a comprehensive review of rare and emerging micro-organisms causing infectious keratitis.

MATERIAL AND METHODS

A literature search was performed using PubMed Medline, Cochrane Library Database, EMBASE and Scopus (1960 onwards), using the terms: keratitis caused by rare pathogens; mycotic keratitis; fungal keratitis; bacterial keratitis; infectious keratitis; infective keratitis; atypical fungal keratitis; fungal keratitis caused by rare organisms; fungal keratitis caused by rare ocular pathogen; atypical bacterial keratitis; bacterial keratitis caused by rare organisms; bacterial keratitis caused by rare ocular pathogen. All relevant articles were included in this review.

RESULTS

A total of 1232 articles matched our search strategy of which 124 articles were included in this mini-review. The rare and emerging bacteria causing keratitis include atypical mycobacteria, Nocardia spp., Chrysebacterium spp., Delftia acidovorans, Kocuria spp., Enterococcus spp., Bartonella henslae, Achromobacter spp. and others. The rare and emerging fungi causing keratitis include Pythium spp., Alternaria spp., Acremonium spp., Cladosporium spp., Curvularia spp., Bipolaris spp., Microsporidia spp., Pseudallescheria spp., Colletotrichum spp., and others. The clinical presentation of these cases is variable. While a few organisms produce characteristic clinical features, rest present similar to bacterial or fungal keratitis with variable response to routine treatment. A strong degree of suspicion is therefore essential for its diagnosis. Special investigations like polymerase chain reaction, gene sequencing, mass spectroscopy and enzyme-linked immunosorbent assay are required for accurate identification of these organisms. Culture-sensitivity is extremely useful as drug resistance to routinely used anti-microbial drugs is common. Prognosis is usually poor for keratitis with Pythium spp., Pseudallescheria spp., Arthrographis spp., Purpureocillium spp., Kociria spp. and Achromobacter spp.

CONCLUSION

Keratitis caused by rare and emerging micro-organisms must be suspected in cases where the infection runs an unusual course or shows a poor response to standard anti-microbial drugs. Early diagnosis and timely treatment hold the key for a good outcome.

Paecilomyces lilacinus Keratitis in a Soft Contact Lens Wearer

We describe a case of keratitis caused by Paecilomyces lilacinus in a contact lens wearer with a history of diabetes.