An unusual case of Acanthamoeba Polyphaga and Pseudomonas Aeruginosa keratitis
Diagnostic Pathology
An unusual case of Acanthamoeba Polyphaga and Pseudomonas Aeruginosa keratitis
Jiaxu Hong 0
Jian Ji 0
Jianjiang Xu 0
Wenjun Cao 0
Zuguo Liu
Xinghuai Sun 0
0 Department of Ophthalmology and Visual Science , Eye, Ear, Nose , and Throat Hospital, School of Shanghai Medicine, Fudan University , 83 Fenyang Road, Shanghai 200031 , China
A 56-year-old woman with a history of disposable soft contact lens wear was referred to our university eye center for a corneal ulcer. Based on the microbial culture, the initial diagnosis was bacterial keratitis, which was unresponsive to topical fortified antibiotics. The patient was then examined using in vivo confocal microscopy, which revealed Acanthamoeba infection. This case emphasizes the need to suspect Acanthamoeba infection in soft contact lens wearers who present with progressive ulcerative keratitis or progressively worsening corneal ulcers that are not responsive to the usual antimicrobial therapy. It is also important to consider the possibility of a coinfection with bacterial and Acanthamoeba species.
Contact lens; Acanthamoeba species; Pseudomonas aeruginosa
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Background
Acanthamoeba keratitis (AK) is a destructive disease
characterized by significant visual morbidity, and prompt
diagnosis is important for a good visual outcome. Like
AK, Pseudomonas aeruginosa keratitis usually progresses
rapidly and presents with suppurative stromal infiltrate
and marked mucopurulent exudate. It should be noted
that there is a possibility, in theory, that AK can develop
in eyes with advanced bacterial keratitis. Coinfections
with other microorganisms have been reported in
patients with culture-proven AK [1,2]. However, the exact
clinical characteristics of such mixed infections remain
unknown. Few publications have addressed this issue.
Herein, we report an unusual case of coinfection with
Acanthamoeba polyphaga and Pseudomonas aeruginosa
as causes of corneal keratitis in a contact lens wearer in
Shanghai.
Case presentation
A 56-year-old female teacher presented with a two-week
history of increasing pain and redness in the left eye.
The patient had a five-year history of disposable soft
contact lens wear and was sometimes careless with the
disinfecting routine. Occasionally, she would rinse her
contact lenses and case in tap water instead of a sterile
saline solution. The patient stated that she had no history
of ocular trauma, overnight contact lens wear,
hypertension, or diabetes. She had no known drug allergies and no
systemic infections at the time of her presentation. She
had been treated one week previously for a P. aeruginosa
corneal ulcer and had received topical fortified tobramycin
and levofloxacin, to which the organism had shown
sensitivity in the laboratory (Figures 1A and D). She denied any
significant improvement of her symptoms and signs. On
examination, her best-corrected visual acuities were
counting fingers in the left eye and 20/20 in the right. She
had a large central corneal ulcer with an underlying
grayish-white, paracentral, ring-shaped stromal infiltrate
(Figure 1B). The hypopyon in the anterior chamber had
improved significantly after the initial treatment with
the topical antibiotics. The right eye was normal. The
patient was examined using an in vivo confocal
microscopy (IVCM). Interestingly, the IVCM images showed
the presence of oval to round, double-walled, highly
refractile structures with a polygonal inner wall,
varying 1225 m in size. The morphology was consistent
with that of Acanthamoeba cysts reported in other
Figure 1 An unusual keratitis case of coinfection with Acanthamoeba polyphaga and Pseudomonas aeruginosa. (A) Slit-lamp microscopic
image of the left eye showed severe central corneal infiltrate (blue arrow) with intensive conjunctival injection. The anterior chamber had 20%
hypopyon (black arrow). (B) After 1 week of treatment with topical antibiotics, a large central corneal ulcer with an underlying grayish-white,
paracentral, ring-shaped stromal infiltrate was identified. (C) After 12 months of treatment with topical antibiotics, the left eye displayed no signs
of inflammation, but there were some superficial blood vessels in the peripheral cornea and a large, central corneal scar obscuring the visual axis.
(D) Microbiological cultures obtained from a superficial corneal swab showed the presence of Pseudomonas aeruginosa.I. (E) In vivo confocal
microscopy examination showed the presence of oval to round, double-walled, highly refractile structures with a polygonal inner wall, varying
1225 m in size (red arrow), with infiltration of inflammatory cells (blue arrow). (F) The Acanthamoeba cysts could not be detected by IVCM
examination after 12 months of treatment.
articles [3,4]. The structures were surrounded by
inflammatory cells (Figure 1E).
Upon confirmation of the presence of the Acanthamoeba
species via the IVCM examination, an additional
treatment regimen of topical 0.2% metronidazole and 0.02%
polyhex (...truncated)