Phialemonium obovatum keratitis after penetration injury of the cornea Kwon-Ho Hong, M.D., Sung-Dong Chang, M.D. Department of Ophthalmology, School of Medicine, Dongsan Medical Center, Keimyung University, Daegu, Korea

INTRODUCTION The incidence of fungal keratitis has been considerably increased for the past years. The causative fungi include filamentous fungi in ocular trauma and nonfilamentous fungi in chronic ocular surface disease. With the expanded use of antibiotic eye drops, the increased use of steroid eye drop and the advancement of laboratory diagnostic tools, the incidence of fungal keratitis has been greatly increased compared to the past. Phialemonium genus is dematiaceous fungi, which is known as the causative fungus for opportunistic infection in immunocompromised hosts. It is isolated from soil, air, water or sewage. In very rare cases, it has been reported to be a cause of invasive disease. We experienced a case in which the keratitis was developed during a monitoring of clinical course after the primary closure of corneal laceration. In cultures of samples obtained from the corresponding patient, Phialemonium obovatum was identified although it has not ever been reported to be the causative fungus for infectious ocular disease.

A 54-year-old man suffered injury during road construction when a nail fragment was stuck in his left eye. He was referred to us from a local clinic for further evaluation and treatment. At the time of admission, his visual acuity was 0.8 in the right eye and hand motion (HM) in the left eye. Slit lamp examination revealed a full-thickness corneal laceration 6.5 mm in size spanning from the 4 o’clock to the 7 o’clock position in the vicinity of the corneal limbus. A part of swollen lens was anteriorly displaced and a hyphema was present. The patient was treated with primary closure of the lacerated cornea. He had a one- year history of hypertension and was taking oral antihypertensives. He had no history of diabetes. However, at the time of admission, his serum glucose was 491 mg/dL, and viral markers were all negative. There was no history of other systemic disease. On postoperative day 1, the patient’s visual acuity was HM, and the suture site was clear. A small amount of viscoelastics remained in the anterior chamber. (Figure A) CASE A

Approximately two weeks after surgery, the patient was noted to have an epithelial defect and subepithelial and stromal cell infiltrates at the suture site. However KOH smear and Gram stain were negative. We subjected the sample to bacterial and fungal culture. Meanwhile, The corneal cellular infiltrate and the corneal epithelial defect progressed. The cellular infiltrate was ring-shape d, which was suggestive of various possible causes of keratitis: fungus, pseudomonas, acanthameba, immune reaction, or toxic keratitis. The smear tests were negative for bacteria and fungi, so the patient was thought to have toxic keratitis. The Pred-Forte ® (prednisolone acetate 1%, Allergan, Waco, TX, USA) dose was therefore increased and was applied to the eye in combination with Vigamox ® (moxifloxacin hydrochloride 0.5%, Alcon Laboratory, Fort Worth, TX, USA) at two-hour intervals. Nevertheless, the patient’s symptoms did not improve. (Figure A) CASE A

By approximately three weeks after surgery, the infiltration involved an extensive area of the cornea, the symptoms had worsened, and stromal melting had developed. The anterior chamber was no longer visible due to corneal haze. Approximately ten days after culture specimen inoculation, P. obovatum was identified (Figure A, B). Natacin ® (natamycin, Alcon Laboratory, Fort Worth, TX, USA) was applied to the eye every two hours. Thereafter, the corneal inflammation remained stable, and the cornea itself underwent minimal change. However, corneal thinning and a persistent epithelial defect were noted in the central cornea. This led to permanent amniotic membrane transplantation (P-AMT) and temporary amniotic membrane transplantation (T-AMT). CASE A B

Approximately three weeks after the AMT was performed, the P-AMT was peeled off, except for the periphery. The corneal epithelium was almost completely replaced with conjunctival epithelium. However, a small epithelial defect remained in the periphery, corneal haze was still present,and neovascularization was seen in the peripheral cornea. The patient was subjected to a single subconjunctival injection of bevacizumab (2.5 mg/0.1mL) (Avastin ®, Genentech, Inc., San Francisco, CA, USA). Approximately seven weeks after the AMT, the visual acuity was HM, and the corneal epithelium was completely conjunctivalized. In the periphery, however, a greater ingrowth of blood vessels was observed. The corneal transplantation was recommended due to persistent diffuse corneal opacity (Figure A), but the patient refused it due to financial reason. CASE A

DISCUSSION Fungal keratitis may be occurred secondary to trauma, and its incidence is increased by the use of steroids and broad-spectrum antibiotics. It commonly occurs in subtropical rural areas in persons engaged in agriculture or in those with immune compromise. Nevertheless, the epidemiologic distribution and source organisms are variable, and the epidemiology is dependent on the geographic area. The most common causative organism worldwide is Aspergillus. There is one report that Aspergillus genus was also the most common causative strain (27.2%) in Korea. This was followed in frequency by Cephalosporium (Acremonium) (18.2%), Chloridium glaucum (10.4%), and Candida albicans (9.1%). Phialemonium genus is intermediate in form between Acremonium and Phialophora. It was first described by Gams and McGinnis in Based on the degree of pigmentation and its conidial shape, it is classified into three types. P. obovatum forms white to pale yellow or greenish colonies that initially produce green diffusible pigment and later produce black pigment at the colony center. On light microscopy, the conidial shape has an obovate form. During a recent 20-year period, 15 reports of 16 cases of Phialemonium genus-induced infections were reported. Three of these infections were intraocular P. curvatum infections. No ocular P. obovatum infections have been reported.

In the current case, keratitis became progressively worse starting approximately two weeks after surgery. The smear tests showed negative result despite of intrastromal cell infiltration showed a ring-shaped pattern. This pattern was assumed to be due to the immune-mediated response. The frequency of steroid eye drop inoculation was increased, and the clinical course was followed closely. However, the patient’s symptoms did not improve. Under the assumption that the persistent epithelial defect and progression of inflammation were due to the toxic effects of the eye drops, the frequency of eye drop inoculation was reduced to four times a day except steroid. The bizarre clinical course led to a delayed diagnosis. After the culture results were revealed, natamycin inoculation was initiated for the treatment of fungal keratitis. However, corneal thinning developed as a result of delayed treatment, and AMT was required. Fungal keratitis is an incurable corneal infection. Because the fungus invades the deep stroma, it cannot be easily cultured in many cases. Furthermore, fungus identification is often difficult to perform on KOH smear or culture. There are also instances in which the toxic effects of eye drops cannot be differentiated from the inflammatory process seen during keratitis recovery. Fungal keratitis may develop in immune compromised hosts, including those with diabetes. The current patient had a blood glucose level of 491mg/dL at the time of admission. The patient was not aware that his blood glucose level was high, and he had not been taking any medications for blood glucose control. It is probable that his hyperglycemia had been present for a long period of time. This might have increased his risk for developing fungal keratitis. DISCUSSION

Conclusion Negative cultures are seen in many patients with fungal keratitis. Early diagnosis allows for administration of appropriate eye drops and surgical treatment, if necessary. Delayed diagnosis can lead to a poor prognosis. Phialemonium infections have been rarely reported. To date, two reports have described three cases of endogenous endophthalmitis due to P. curvatum inoculated through intrapenile injection. Our patient denied a history of such injection. To our knowledge, no case of ocular P. obovatum infection has been reported in the literature. Therefore, we reported a case of fungal keratitis due to P. obovatum, along with a review of the literature