Journal of Postgraduate Medicine Medknow Publications and Staff Society of Seth GS Medical College and KEM Hospital, Mumbai, India ISSN: 0022-3859 EISSN: 0972-2823 Vol. 52, Num. 2, 2006, pp. 155-157

Journal of Postgraduate Medicine, Vol. 52, No. 2, April-June, 2006, pp. 155-157

Letter To Editor

Keratitis due to Cylindrocarpon lichenicola

Kaliamurthy J, Jesudasan CAN, Prasanth DA, Thomas PA

Departments of Microbiology and Ophthalmology Institute of Ophthalmology, Joseph Eye Hospital, Tiruchirappalli - 620001, Tamilnadu
Correspondence Address:Departments of Microbiology and Ophthalmology Institute of Ophthalmology, Joseph Eye Hospital, Tiruchirappalli - 620001, Tamilnadu, philipthomas@satyam.net.in

Code Number: jp06052

Sir,

Ulceration of the cornea due to fungi (mycotic keratitis) is an important ophthalmologic problem in the developing world, where agriculturalists are at risk for ocular trauma by fungus-laden plant material or soil particles.[1] Keratitis caused by rare or emerging fungi may pose diagnostic challenges to the clinician under such circumstances. We describe in this paper, keratitis due to Cylindrocarpon ( Fusarium ) lichenicola , an emerging fungus, in a 56- year-old Indian male.

The patient, a farmer, presented with complaints of pain, redness and irritation of the left eye following ocular injury caused by hay 5 days earlier. He was not a contact lens-wearer and did not give a history of any prior ocular disease. Slit-lamp examination of the affected eye [Figure - 1] revealed a corneal ulcer (6x5 mm) with irregular margins, raised, with necrotic slough, infiltration involving 75% of the corneal thickness and a 1 mm central endothelial plaque. The anterior chamber exhibited aqueous flare and a 2 mm hypopyon, the lens was cataractous and visual acuity was restricted to "hand movements" only. The right eye was normal with a visual acuity of 6/60 (unaided). Since an infection was suspected, scrapings were taken from the base and edges of the corneal ulcer by a sterile blade. Microscopic examination of these scrapings, stained by lactophenol cotton blue [Figure - 2]a and Gram stain, revealed numerous septate fungal hyphae. A presumptive diagnosis of filamentous fungal keratitis was made; treatment was initiated with topical natamycin (5%) and ciprofloxacin (0.3%) hourly and topical mydriatics twice daily. The ulcer initially remained quiescent. However after 5 days of therapy, the ulcer exhibited signs of worsening, necessitating surgical intervention (therapeutic penetrating keratoplasty [TPK]). Histopathological examination of the infected corneal button removed at surgery revealed numerous septate fungal hyphae [Figure - 2]b. This graft became opaque, so TPK was repeated after two weeks. This second graft also underwent opacification. The patient refused further surgery and the eye eventually went in for phthisis bulbi.

Scrapings inoculated onto Sabouraud glucose-neopeptone agar (SDA) [Figure - 3]a and sheep blood agar grew cottony, white-red fungal colonies within 48 hours. The reverse of the fungal colony on SDA exhibited brown pigmentation. The fungus was identified as Cylindrocarpon lichenicola since there were: branched, septate, hyaline hyphae; phialides on simple or sparsely-branched conidiophores; cylindrical to fusiform, smooth-walled macroconidia, each with 3 to 6 septa, a blunt rounded apex and distinctly truncate base [Figure - 3]b; smooth-walled chlamydoconidia on short branches.[2] There was no bacterial growth in culture. Culture of the infected corneal button also grew C. lichenicola .

Cylindrocarpon species occur in the soil as saprophytic or weak pathogenic fungi on the roots of many herbaceous and woody plants in India and other tropical countries.[3] Cylindrocarpon thrives in the soil of southern India, where temperatures and humidity remain relatively high all year round[3] and is a common agent of post-harvest fruit invasion.[2] Thus, agriculturalists and outdoor workers may become accidentally infected with Cylindrocarpon while at work . Cylindrocarpon species may cause non-ocular infections (athlete′s foot, intertrigo, mycetoma and peritonitis) in humans.[4] Cylindrocarpon keratitis appears to occur very rarely;[5],[6],[7] the species involved have been. C. lichenicola (originally called Fusarium lichenicola and later Cylindrocarpon tonkinense ) and Cylindrocarpon vaginae.

The taxonomic status of Cylindrocarpon species is currently unsettled. Some species of Cylindrocarpon and Fusarium share teleomorphs (sexual forms) in the genus Nectria . Also, sequencing of ribosomal DNA revealed that C. lichenicola is well-instituted within a clade of typical F. solani strains, prompting Summerbell and Schroers[8] to conclude that C. lichenicola should be known by its original name Fusarium lichenicola . However, since C. lichenicola is yet to be comfortably removed from its current genus and associated with Fusarium ,[8] we are reporting this isolate to be Cylindrocarpon ( Fusarium) lichenicola.

C. lichenicola is sometimes misidentified as F. solani .[2] However, C. lichenicola differs from F. solani in forming macroconidia which are predominantly straight rather than curved, by having apical cells that are rounded rather than tapering and basal cells with truncate and offset rather than attenuated pedicels (foot cells), by lacking microconidia, by having pigmented chlamydoconidia and by a brown color rather than cream-colour on reverse of SDA medium. Our fungal isolate exhibited these features of C. lichenicola [Figure - 3]b.

In our patient, the cornea probably became ulcerated and infected with Cylindrocarpon ( Fusarium ) lichenicola following ocular injury by soil-contaminated hay containing Cylindrocarpon spores (conidia). Due to inadequate treatment before presentation, the ulcer probably worsened, so that the patient presented to us with severe keratitis. After initiating hourly topical natamycin treatment, the ulcer remained quiescent for 5 days; however, a rapid deterioration necessitated TPK. Successful treatment of Cylindrocarpon tonkinensis keratitis by using topical natamycin 5% has been reported.[5] However, others have reported less favorable outcomes for Cylindrocarpon keratitis, even with the best available treatment.[7] These earlier reports and our present experience, indicate that Cylindrocarpon spp. may cause a severe form of keratitis that responds poorly to medical or surgical intervention. Hence, clinicians should suspect fungal infections in corneal ulcers that arise following injury by plant material or soil and institute suitable diagnostic and therapeutic measures as early as possible.

References

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