Mycotic keratitis (an infection of the cornea) is an important ocular infection, especially in young male outdoor workers. There are two frequent presentations: keratitis due to filamentous fungi (Fusarium, Aspergillus, phaeohyphomycetes and Scedosporium apiospermum are frequent causes) and keratitis due to yeast-like fungi (Candida albicans and other Candida species). In the former, trauma is usually the sole predisposing factor, although previous use of corticosteroids and contact lens wear are gaining importance as risk factors; in the latter, there is usually some systemic or local (ocular) defect. The clinical presentation and clinical features may suggest a diagnosis of mycotic keratitis; increasingly, in vivo (non-invasive) imaging techniques (confocal microscopy and anterior segment optical coherence tomography) are also being used for diagnosis. However, microbiological investigations, particularly direct microscopic examination and culture of corneal scrape or biopsy material, still form the cornerstone of diagnosis. In recent years, the PCR has gained prominence as a diagnostic aid for mycotic keratitis, being used to complement microbiological methods; more importantly, this molecular method permits rapid specific identification of the aetiological agent. Although various antifungal compounds have been used for therapy, management of this condition (particularly if deep lesions occur) continues to be problematic; topical natamycin and, increasingly, voriconazole (given by various routes) are key therapeutic agents. Therapeutic surgery, such as therapeutic penetrating keratoplasty, is needed when medical therapy fails. Increased awareness of the importance of this condition is likely to spur future research initiatives.

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.

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Aim. To report the aetiological spectrum and susceptibility patterns of bacteria isolated from patients with corneal ulceration. Method. The microbiological data of all patients with suspected infectious corneal ulceration who presented to the ocular microbiology service at this centre between 2005 and 2012 were reviewed retrospectively. Result. Microorganisms were recovered from 1665 (77%) of the 2170 ulcers. Bacterial isolates accounted for 1205 of the organisms isolated. The most common bacterial pathogens isolated were various species of Staphylococcus, representing 777 (64.5%), followed by Staphylococcus spp. (148; 12.3%) and Pseudomonas aeruginosa (117; 9.7%). High percentages of Gram-positive bacteria were susceptible to gatifloxacin (>94%), followed by ofloxacin and moxifloxacin. Almost 90% of Pseudomonas aeruginosa isolates were susceptible to ciprofloxacin and moxifloxacin. Sixty-two (44%) of 140 isolates of Streptococcus pneumoniae, 79 (14.8%) of 534 isolates of Staphylococcus epidermidis, and 33 (14%) of 234 isolates of Staphylococcus aureus were resistant to three or more antibiotics. Conclusion. Staphylococcus spp. were the most common bacterial pathogens isolated from patients with keratitis in this setting. High percentages of Gram-positive and Gram-negative bacteria were susceptible to gatifloxacin and moxifloxacin, respectively. Interestingly, a high percentage of Streptococcus pneumoniae isolates were found to be resistant to three or more antibiotics.

Topical natamycin should continue to be considered as the treatment of choice for filamentous fungal keratitis; when natamycin is unavailable, topical itraconazole therapy could be used, particularly if the infections are due to Aspergillus or Curvularia spp.