Aetiology of suppurative corneal ulcers in Ghana and south India, and epidemiology of fungal keratitis

Abstract

Background: A multicentre study was carried out in Ghana and southern India to determine the aetiology of suppurative keratitis in two regions located at similar tropical latitudes. Studies of fungal keratitis from the literature were reviewed. Methods: Patients presenting at rural and urban eye units with suspected microbial keratitis were recruited to the study. Corneal ulceration was defined as loss of corneal epithelium with clinical evidence of infection with or without hypopyon. Microscopy and culture were performed on all corneal specimens obtained. Results: 1090 patients were recruited with suspected microbial keratitis between June 1999 and May 2001. Overall the principal causative micro-organisms in both regions were filamentous fungi (42%): Fusarium species and Aspergillus species were the commonest fungal isolates. Pseudomonas species were most frequently isolated from cases of bacterial keratitis in Ghana but in India the commonest bacterial isolates were streptococci. Conclusion: Infections of the cornea due to filamentous fungi are a frequent cause of corneal damage in developing countries in the tropics and are difficult to treat. Microscopy is an essential tool in the diagnosis of these infections. A knowledge of the "local" aetiology within a region is of value in the management of suppurative keratitis in the event that microscopy cannot be performed.

A profile of corneal ulcers – 2 years study from rural hospital, Haryana

“…Bharathi et al 8 (34.4%) and Ghana study by leek et al 9 (37.6%) has shown lesser incidence whereas Geethakumari et al 4 (69.78%) has reported a much higher incidence of fungal keratitis. It may be due to hot and humid climate of this region.…”

Pathogenesis of microbial keratitis

“…A strong geograph ical correlation has been reported to exist between the occurrences of different types of keratomycosis. For example, the proportion of keratitis due to yeast-like fungi show a tendency to increase towards temperate climates whereas corneal ulcers caused by filamentous fungi appear to be more common towards tropical latitudes [100].…”

Pattern recognition receptors in microbial keratitis

“…[119][120][121] In developing countries, ocular trauma is a major risk factor. 31,122,123 Fungal spores are able to penetrate compromised epithelium where they germinate, expressing β-glucan and α-mannan molecules on their surface. These are recognised by the receptors Dectin-1 and Dectin-2 on macrophages, which then signal via spleen tyrosine kinase (Syk) and CARD 9 proteins to activate the NF-kB pro-inflammatory pathway.…”