|Year : 2014 | Volume
| Issue : 1 | Page : 32-34
Case study of aspergillus flavus causing unilateral acute progressing corneal melt
S. K. Prabhakar1, G. S. Vijaykumar2, S. Rohit Rao3
1 Department of Ophthalmology, Jagadguru Sri Shivarathreeswara Medical College and Hospital, Mysore, Karnataka, India
2 Department of Microbiology, Jagadguru Sri Shivarathreeswara Medical College and Hospital, Mysore, Karnataka, India
3 Department of Post Graduate in Ophthalmology, Jagadguru Sri Shivarathreeswara Medical College and Hospital, Mysore, Karnataka, India
|Date of Web Publication||13-Jun-2014|
S. K. Prabhakar
Department of Ophthalmology, Jagadguru Sri Shivarathreeswara Medical College and Hospital, Mysore, Karnataka
Source of Support: None, Conflict of Interest: None
Twenty-eight-year-old female patient, reported with history of acute painful loss of vision, following contact with Parthenium plants 15 days ago. Slit lamp examination showed 4-5 mm circumscribed thick plaque of slough in the central cornea with satellite infiltration and tenacious hypopyon. Ten percent potassium hydroxide (KOH) preparation of the slough revealed plenty of septate fungal hyphae. Topical Natamycin was instilled with no improvement. Ulcer debridement was done and thick plaque was subjected to microbiological examination. Fungal culture yielded Aspergillus flavus. Topical Amphotericin B was added along with Natamycin. Despite good response the condition progressed to quick melting and perforation. Crystalline lens extruded through the perforation, after several bouts of sneezing. Perforation was managed by therapeutic corneal grafting. Drug resistance, drug toxicity, corneal thinning and the strain by the patient might explain the disease progression. Factors causing corneal melt and the measures adopted to prevent the intraocular spread are presented.
Keywords: Aspergillus (A), MK (McCarey-Kaufman) medium, therapeutic penetrating keratoplasty (TPK)
|How to cite this article:|
Prabhakar SK, Vijaykumar GS, Rao SR. Case study of aspergillus flavus causing unilateral acute progressing corneal melt. J Acad Clin Microbiol 2014;16:32-4
|How to cite this URL:|
Prabhakar SK, Vijaykumar GS, Rao SR. Case study of aspergillus flavus causing unilateral acute progressing corneal melt. J Acad Clin Microbiol [serial online] 2014 [cited 2017 May 23];16:32-4. Available from: http://www.jacmjournal.org/text.asp?2014/16/1/32/134463
| Introduction|| |
Keratomycosis is a common corneal fungal disease that affects agriculturists in tropical and subtropical countries. The fungal spores gain access into the cornea by accidental traumatic implantation of the vegetations. Fusarium species are the most common keratomycotic organisms reported worldwide. An epidemiological study from the southern part of India reported 75% culture-proven cases were due to Aspergillus (A.) flavus and Aspergillus fumigatus and was isolated in 11.5% cases.  A. flavus is replacing the fusarium species as the leading fungal agents causing mycotic corneal infections in south India. Aflotoxin released by A. flavus is responsible for all the ocular tissue damage.  Less common Aspergillus species causing keratomycosis such as A. tamari, A. nomius and A. brasiliensis were reported. ,, Untreated, such cases have a bad prognosis in the form of acute corneal perforation with eventual loss of vision.
We report a case of keratomycosis due to A. flavus, the factors leading to corneal perforation, the effectiveness of antifungal agents and the measures adopted in preventing further disease spread by corneal grafting.
| Case report|| |
A 28-year-old female patient reported with history of painful loss of vision in the left eye following contact with Parthenium plants and vigorous rubbing on 29 th May 2013. Topical Natamycin and cycloplegics were instilled, with no improvement. Slit lamp examination revealed a 4-5 mm circumscribed thick plaque of slough in the central cornea, surrounded by satellite infiltration and tenacious hypopyon. Anterior chamber infiltrates were irregular and thick with feathery margins [Figure 1].
|Figure 1: Characteristic disciform appearance of the slough in Aspergillus fl avus keratitis|
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Corneal scrapings were cultured on the sheep blood agar (SBA) for bacterial growth and Sabourauds Dextrose Agar (SDA) for fungal growth. SBA was incubated at 37 o C and SDA was incubated at room temperature. Ten percent potassium hydroxide (KOH) preparation showed plenty of broad fungal hyphae. Immediate corneal ulcer debridement was done. A wedge biopsy of the central thick plaque was taken and inoculated in the fungal and bacterial culture media. Bacterial culture remained sterile after 48-hours incubation. A. flavus was grown on SDA from both the clinical samples. Topical intensive treatment was started using freshly prepared Amphotericin B 15 mg/ml dissolved in artificial tears every 30 minutes during the daytime and hourly at night. Topical Natamycin 5% and cycloplegic regimen was continued. Acetazolamide 250 mg three times daily was given orally to control the intraocular pressure with oral Ketaconazole 200 mg twice daily.
All the symptoms were relieved on the 4 th day, with dramatic resolution of the anterior chamber infiltrates except for the central thick slough [Figure 2]. The patient was discharged, but returned on 9 th June with severe eye pain and headache, following several episodes of sneezing. Examination showed central corneal perforation, sealed by blood tinged prolapsed iris. Perception of light was present [Figure 3]. Further on sneezing, the crystalline lens extruded along with vitreous. Therapeutic penetrating keratoplasty was performed under general anaesthesia by using McCarey-Kaufman (MK) medium preserved donor cornea. The condition was stabilized with reformation of the anterior chamber and optically clear cornea maintained with a vision of hand movements [Figure 4].
|Figure 2: Resolution of the corneal and anterior chamber infi ltrates with combined antifungal agents|
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|Figure 3: Large central corneal perforation with purulent blood stained iris prolapse|
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|Figure 4: Three months postoperative picture after therapeutic corneal grafting|
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| Discussion|| |
The population at risk, for exposure to corneal mycotic infections are typically farmers and agriculturists. Rubbing of the eye with contaminated fingers causes fungal elements to be directly inoculated into the abraded corneal epithelium. On topical instillation of corticosteroids, there is intense multiplication of the fungal agent. In the present case study, Aspergillus spores could have gained access into the desquamated corneal epithelium due to rubbing of the eye with contaminated parthenium plants. Initial clinical response with topical Natamycin alone was not sufficient, probably due to the low dosage and low frequency of applications. After ulcer debridement, topical Natamycin and Amphotericin-B combination with systemic Ketoconazole administration was effective in resolving the corneal infiltrates and hypopyon.
Topical corticosteroids were not used in the present case, as compared to the previous report of using the steroid eye drops that intensified corneal melting. It is interesting to note that the clinical appearance of A. flavus keratitis in our patient was similar to the previous case report.  The classical pattern of circumscribed tough plaque of slough was observed in both the case studies. This clinical picture may be considered as the sign of A. flavus keratitis that warrants therapeutic corneal grafting. The initial improvement with the administration of oral Voriconazole (as opposed to Ketoconazole in this case study) was the other similarity. Successful results were also reported, on using Thiobendazole 4% suspension for A. flavus keratitis in the previous reports. 
Identifying the fungal species is essential for proper management of corneal mycotic infections and could prevent visual loss. Development of drug resistance is unlikely in the present case, as there was good response to the given therapy, although A. flavus isolates have higher minimum-inhibitory-concentration (MICs) compared to A. fumigatus. On the other hand, emergence of drug toxicity could have caused corneal thinning leading to corneal perforation. The severity of tissue destruction is possibly mediated by the increased collagenase activity of A. flavus. Knowing the antifungal susceptibility pattern could have prevented progression of corneal melting. However, species characterisation may not be possible in most of the institutions in India. Episodes of sneezing and ongoing corneal thinning, secondary to severe tissue destruction by necrosis were other predisposing factors that caused corneal perforation. The infected cornea was replaced by MK medium preserved donor cornea that provided excellent structural and functional globe integrity, comparable to the successful use of cryo-preserved corneas. 
In conclusion, administration of topical Natamycin and Amphotericin B was effective in resolution of the infiltrates along with systemic Ketoconazole that provided efficient antifungal coverage. Although the infection was well-controlled, progressive corneal thinning was complicating the clinical course. Corneal grafting arrested the progression of deeper spread of the infection and provided good optical medium for visual rehabilitation. Susceptibility pattern may be considered in such difficult cases.
| Acknowledgement|| |
We are thankful to International Lions Eye Bank, Bangalore for providing donor cornea for the patient in time.
| References|| |
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]