An unusual case of Acanthamoeba Polyphaga and Pseudomonas Aeruginosa keratitis

Diagnostic Pathology, Sep 2018

Virtual Slides The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/5168343391150859 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.

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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 - 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)


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Jiaxu Hong, Jian Ji, Jianjiang Xu, Wenjun Cao, Zuguo Liu, Xinghuai Sun. An unusual case of Acanthamoeba Polyphaga and Pseudomonas Aeruginosa keratitis, Diagnostic Pathology, 2014, pp. 105, 9, DOI: 10.1186/1746-1596-9-105