Phialemonium obovatum keratitis after penetration injury of the cornea

1
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
2
INTRODUCTION

• The incidence of fungal keratitis has been
  considerably increased for the past 20-30 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.

3
CASE

• 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
  oclock to the 7
• oclock 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 patients visual
  acuity was
• HM, and the suture site was clear. A small amount
  of
• viscoelastics remained in the anterior chamber.
• (Figure A)

A
4
CASE

• 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 patients symptoms did not
  improve.
• (Figure A)

A
5
CASE

• 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).

A
B
6
CASE

• 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.

A
7
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 1983. 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.

8
DISCUSSION

• 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 patients 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.

9
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