Clinico-demographical profile of keratomycosis in Delhi, North India

Global research on keratomycosis: New insights from latent Dirichlet allocation and HJ-Biplot-driven knowledge mapping study

BACKGROUND

Keratomycosis is a form of infectious keratitis, an infection of the cornea, which is caused by fungi. This disease is a leading cause of ocular morbidity globally with at least 60 % of the affected individuals becoming monocularly blind.

OBJECTIVE

This bibliometric analysis aimed to comprehensively assess the existing body of literature, providing insights of the evolution of keratomycosis research by identifying key themes and research gaps.

METHODS

This work used the modeling method Latent Dirichlet Allocation (LDA) to identify and interpret scientific information on topics concerning existing categories in a set of documents. The HJ-Biplot method was also used to determine the relationship between the analyzed topics, taking into consideration the years under study.

RESULTS

This bibliometric analysis was performed on a total of 2,599 scientific articles published between 1992 and 2022. The five leading countries with more scientific production and citations on keratomycosis were The United States of America, followed by India, China, United Kingdom and Australia. The top five topics studied were Case Reports and Corneal Infections, which exhibited a decreasing trend; followed by Penetrating Keratoplasty and Corneal Surgery, Ocular Effects of Antifungal Drugs, Gene Expression and Inflammatory Response in the Cornea and Patient Data which have been increasing throughout the years. However Filamentous Fungi and Specific Pathogens, and Antifungal Therapies research has been decreasing in trend.

CONCLUSION

Additional investigation into innovative antifungal drug therapies is crucial for proactively tackling the potential future resistance to antifungal agents in scientific writing.

Fungal keratitis in Iran: Risk factors, clinical features, and mycological profile

Introduction

This study was intended to investigate the clinical features and predisposing factors of fungal keratitis (FK), as well as molecular identification and antifungal susceptibility of causative agents in Tehran, Iran.

Methods

This cross-sectional study was carried out from April 2019 to May 2021. All fungi isolates were identified using conventional methods and were confirmed by DNA-PCR-based molecular assays. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) was used to identify yeast species. Minimum inhibitory concentrations (MIC) of eight antifungal agents were assessed according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) microbroth dilution reference method.

Results

Fungal etiology was confirmed in 86 (7.23%) of 1189 corneal ulcers. A significant predisposing factor for FK was ocular trauma caused by plant materials. Therapeutic penetrating keratoplasty (PKP) was required in 60.4% of cases. The predominant fungal species isolated was Fusarium spp. (39.5%) followed by Aspergillus spp. (32.5%) and Candida spp. (16.2%).

Discussion

The MIC results indicate that amphotericin B may be appropriate for treating FK caused by Fusarium species. FK caused by Candida spp. can be treated with flucytosine, voriconazole, posaconazole, miconazole, and caspofungin. In developing countries such as Iran, corneal infection due to filamentous fungi is a common cause of corneal damage. In this region, fungal keratitis is observed primarily within the context of agricultural activity and subsequent ocular trauma. Fungal keratitis can be managed better with understanding the "local" etiologies and antifungal susceptibility patterns.

GENERATION AND USE OF FUNCTIONALISED HYDROGELS THAT CAN RAPIDLY SAMPLE INFECTED SURFACES

This paper outlined our method for developing polymer-linked contact lens type materials for rapid detection and differentiation of Gram-positive, Gram-negative bacteria and fungi in infected corneas. It can be applied to both model synthetic or ex-vivo corneal models and has been successfully trialed in an initial efficacy tested animal study. First a hydrogel substrate for the swab material is selected, we have demonstrated selective swabs using a glycerol monomethacrylate hydrogel. Alternatively any commercial material with carboxylic acid functional groups is suitable but risks nonspecific adhesion. This is then functionalised via use of N-hydroxysuccinimide reaction with amine groups on the specified highly branched polymer ligand (either individually gram negative, gram positive or fungal binding polymers or a combination of all three can be employed for desired sensing application). The hydrogel is then cut into swabs suitable for sampling, used, and then the presence of gram positive, game negative and fungi are disclosed by the sequential addition of dyes (fluorescent vancomycin, fluorescein isothiocyanate and calcofluor white).

In summary this method presents:

Method to produce glycerol monomethacrylate hydrogels to minimize nonspecific binding

Methods of attaching pathogen binding highly branched polymers to produce selective hydrogel swabs

Method for disclosing bound pathogens to this swab using sequential dye addition

Mycotic Keratitis-A Global Threat from the Filamentous Fungi

Mycotic or fungal keratitis (FK) is a sight-threatening disease, caused by infection of the cornea by filamentous fungi or yeasts. In tropical, low and middle-income countries, it accounts for the majority of cases of microbial keratitis (MK). Filamentous fungi, in particular Fusarium spp., the aspergilli and dematiaceous fungi, are responsible for the greatest burden of disease. The predominant risk factor for filamentous fungal keratitis is trauma, typically with organic, plant-based material. In developed countries, contact lens wear and related products are frequently implicated as risk factors, and have been linked to global outbreaks of Fusarium keratitis in the recent past. In 2020, the incidence of FK was estimated to be over 1 million cases per year, and there is significant geographical variation; accounting for less than 1% of cases of MK in some European countries to over 80% in parts of south and south-east Asia. The proportion of MK cases is inversely correlated to distance from the equator and there is emerging evidence that the incidence of FK may be increasing. Diagnosing FK is challenging; accurate diagnosis relies on reliable microscopy and culture, aided by adjunctive tools such as in vivo confocal microscopy or PCR. Unfortunately, these facilities are infrequently available in areas most in need. Current topical antifungals are not very effective; infections can progress despite prompt treatment. Antifungal drops are often unavailable. When available, natamycin is usually first-line treatment. However, infections may progress to perforation in ~25% of cases. Future work needs to be directed at addressing these challenges and unmet needs. This review discusses the epidemiology, clinical features, diagnosis, management and aetiology of FK.

Etiological spectrum of infectious keratitis in the era of MALDI-TOF-MS at a tertiary care hospital

Background:

Infectious Keratitis (Ik) Is A Potential Vision-Threatening Ocular Infection Caused By A Variety Of Microorganisms.

Aim:

To Explore Risk Factors And Etiological Agents Associated With Ik.

Design:

A Prospective Cross-Sectional Study In Which Corneal Scrapings From 120 Suspected Cases Were Evaluated At A Tertiary Health Care Institute From January To December 2019.

Methods:

Scrapings Were Subjected To Direct Microscopy, Culture, And Identification By Both Conventional Methods And Maldi-Tof-Ms. The Patient's Demographic Data And Predisposing Factors, If Any Were Recorded.

Results:

The Mean Age Of Patients Was 48.9 Years And Predisposing Factors Were Documented In 46% (55/120) Of Cases. Overall, Infective Etiology Could Be Established In 51% (N = 61/120) Of Cases. Fungal Growth In 26% (N = 31/120) Of Cases And Bacterial Growth In 22% (N = 27/120) Of Cases Was Obtained. Growth Of More Than One Species Of Fungi Or Growth Of Bacteria Along With Fungus Were Observed In 2% (N = 3/120) Of Cases. Of All The Fungal Isolates Obtained (N = 34), The Most Common Isolate Was Fusarium (18/34) Followed By Aspergillus (8/34), Curvularia (4/34), Pseudallescheria Boydii (3/34), And Geotrichum (1/34). Among The Gram-Positive Bacterial Isolates (N = 16), Staphyloccus Species (15/16) Were Isolated In Maximum Number Followed By Streptococcus Pneumoniae (1/16). Among The Gram-Negative Isolates (N = 13), Pseudomonas Species (8/13) Were Isolated In Maximum Number Of Cases, Followed By Acinetobacter (3/13), Klebsiella Pneumoniae (1/13), And Escherichia Coli (1/13).

Conclusion:

For Initiating Appropriate Empirical Therapy, The Knowledge Of The Epidemiological Pattern Of Infectious Keratitis Of A Particular Geographical Region Is Crucial.

The Spectrum of Microbial Keratitis: An Updated Review

Background:

In microbial keratitis, infection of the cornea can threaten vision through permanent corneal scarring and even perforation resulting in the loss of the eye. A literature review was conducted by Karsten, Watson and Foster (2012) to determine the spectrum of microbial keratitis. Since this publication, there have been over 2600 articles published investigating the causative pathogens of microbial keratitis.

Objective:

To determine the current spectrum of possible pathogens implicated in microbial keratitis relative to the 2012 study.

Methods:

An exhaustive literature review was conducted of all the peer-reviewed articles reporting on microbial pathogens implicated in keratitis. Databases including MEDLINE, EMBASE, Scopus and Web of Science were searched utilising their entire year limits (1950-2019).

Results:

Six-hundred and eighty-eight species representing 271 genera from 145 families were implicated in microbial keratitis. Fungal pathogens, though less frequent than bacteria, demonstrated the greatest diversity with 393 species from 169 genera that were found to cause microbial keratitis. There were 254 species of bacteria from 82 genera, 27 species of amoeba from 11 genera, and 14 species of virus from 9 genera, which were also identified as pathogens of microbial keratitis.

Conclusion:

The spectrum of pathogens implicated in microbial keratitis is extremely diverse. Bacteria were most commonly encountered and in comparison, to the review published in 2012, further 456 pathogens have been identified as causative pathogens of microbial keratitis. Therefore, the current review provides an important update on the potential spectrum of microbes, to assist clinicians in the diagnosis and treatment of microbial keratitis.

Filamentous fungal infections of the cornea: a global overview of epidemiology and drug sensitivity

Fungal keratitis is a serious suppurative, usually ulcerative corneal infection which may result in blindness or reduced vision. Epidemiological studies indicate that the occurrence of fungal keratitis is higher in warm, humid regions with agricultural economy. The most frequent filamentous fungal genera among the causal agents are Fusarium, Aspergillus and Curvularia. A more successful therapy of fungal keratitis relies on precise identification of the pathogen to the species level using molecular tools. As the sequence analysis of the internal transcribed spacer (ITS) region of the ribosomal RNA gene cluster (rDNA) is not discriminative enough to reveal a species-level diagnosis for several filamentous fungal species highly relevant in keratitis infections, analysis of other loci is also required for an exact diagnosis. Molecular identifications may also reveal the involvement of fungal species which were not previously reported from corneal infections. The routinely applied chemotherapy of fungal keratitis is based on the topical and systemic administration of polyenes and azole compounds. Antifungal susceptibility testing of the causal agents is of special importance due to the emergence and spread of resistance. Testing the applicability of further available antifungals and screening for new, potential compounds for the therapy of fungal keratitis are of highlighted interest.