Mycotic Keratitis—A Global Threat from the Filamentous Fungi

Abstract

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.

Fusarium Keratitis—Review of Current Treatment Possibilities

“…The annual prevalence of fungal keratitis is estimated to be 1,051,787 cases globally, with the highest estimated amount of incidences in Asia and Africa and the lowest in Europe [ 1 ]. While filamentous fungi are the main cause of fungal keratitis in tropical and subtropical climates, yeasts dominate in temperate climates [ 1 , 2 ]. Among globally reported cases of fungal keratitis, filamentous fungus Fusarium spp.…”

Eye Infections Caused by Filamentous Fungi: Spectrum and Antifungal Susceptibility of the Prevailing Agents in Germany

“…most frequently occurs in patients with chronic eye disease, topical steroid use, or surgical intervention. The spectrum of filamentous fungi causing keratitis differs depending on the climate and geographic region, but Aspergillus and Fusarium species are the predominant causative agents worldwide [ 11 , 12 , 13 ]. In several countries, including India, Nepal, and the USA (Florida), Curvularia species play an important role as the cause of keratitis [ 12 ].…”

Evaluation of Host Defense Peptide (CaD23)-Antibiotic Interaction and Mechanism of Action: Insights From Experimental and Molecular Dynamics Simulations Studies

“…(Ting et al, 2021a) It can be caused by a wide range of organisms, including bacteria, fungi, viruses, and parasites, particularly Acanthamoeba. (Shah et al, 2011;Khor et al, 2018;Ting et al, 2018;Ting et al, 2019a;Green et al, 2019;Khoo et al, 2020;Ting et al, 2021b;Hoffman et al, 2021) Broadspectrum topical antibiotic treatment is the current mainstay of treatment for IK, but the management is being challenged by the low culture yield, (Ting et al, 2021a;Ting et al, 2021b) polymicrobial infection, (Tu et al, 2009;Ting et al, 2019b;Khoo et al, 2020) and emerging AMR. (Hernandez-Camarena et al, 2015;Lalitha et al, 2017;Lin et al, 2019;Asbell et al, 2020) In addition, adjuvant procedures/surgeries such as therapeutic corneal cross-linking, (Ting et al, 2019c) amniotic membrane transplantation, (Ting et al, 2021c) and therapeutic/tectonic keratoplasty (Hossain et al, 2018;Ting et al, 2020a) are often required to manage uncontrolled infection and its complications, including corneal melting and perforation.…”