|Ahead of print publication
Dendrite-like anterior stromal keratitis coinfected with Acanthamoeba and Pseudomonas in an orthokeratology contact lens wearer
Department of Ophthalmology, Taipei Veterans General Hospital; Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
|Date of Submission||27-Nov-2017|
|Date of Acceptance||25-Feb-2018|
|Date of Web Publication||22-May-2018|
Department of Ophthalmology, Taipei Veterans General Hospital, No. 201, Sec. 2, Shih-Pai Road, Taipei 112
Source of Support: None, Conflict of Interest: None
Acanthamoeba species can cause a keratitis misdiagnosed as herpes keratitis or fungal keratitis. We report an unusual dendrite-like anterior stromal keratitis coinfected with Acanthamoeba and Pseudomonas aeruginosa in an orthokeratology contact lens wearer in Taiwan. Topical 1% voriconazole and 0.5% levofloxacin were prescribed because besides Acanthamoeba keratitis, fungal keratitis was also highly suspected initially. Topical 0.02% chlorhexidine was added after the culture of the scraped cornea showed positive results of Acanthamoeba and P. aeruginosa. The lesion subsided using this triple combination therapy for 1 week. Both Acanthamoeba and P. aeruginosa are potentially devastating causes of infectious keratitis. Our case highlights the importance of considering the possibility of a concurrent infection and atypical presentation in cases with contact lens-related keratitis. The use of topical levofloxacin combined with voriconazole should be considered as the first-line treatment in such patients.
Keywords: Acanthamoeba keratitis, coinfection, levofloxacin, orthokeratology, Pseudomonas
|How to cite this URL:|
Hsu CC. Dendrite-like anterior stromal keratitis coinfected with Acanthamoeba and Pseudomonas in an orthokeratology contact lens wearer. Taiwan J Ophthalmol [Epub ahead of print] [cited 2019 Jan 24]. Available from: http://www.e-tjo.org/preprintarticle.asp?id=232966
| Introduction|| |
Acanthamoeba keratitis (AK) is a severe but unusual infectious disease of the cornea. The pathogen, Acanthamoeba, is a free-living cyst-forming protozoan that is distributed in diverse environments including air, soil, dust, and water. The active form of Acanthamoeba is trophozoite which has an amoeboid shape with pseudopodia, phagocytoses any encountered small sized particle and feeds on keratocytes in the cornea. The cystic form can survive in a difficult environment, and an effective treatment of AK needs cysticidal drugs. Unlike AK, Pseudomonas aeruginosa keratitis usually progresses rapidly and presents with significant suppurative stromal infiltrate and mucopurulent exudate. It is thought that AK can develop in eyes with advanced bacterial keratitis. Coinfections with other microorganisms have been reported in patients with culture-proven AK.,,, Herein, we report a case of dendrite-like anterior stromal keratitis coinfected with Acanthamoeba and P. aeruginosa, who was an orthokeratology contact lens wearer in Taiwan.
| Case Report|| |
A 20-year-old male orthokeratology contact lens wearer presented complaining of eye pain and redness in the right eye for 2 days. The patient reported that he had worn orthokeratology contact lens continuously for 30 h. After he removed the contact lens, photophobia of the right eye was noted. He went to a clinic where topical 0.25% chloramphenicol eye drops and 0.5% erythromycin eye ointment were prescribed. He went to our clinics due to the symptoms progressed 1 day later. The slit-lamp examination showed a paracentral dendrite-like anterior stromal infiltration with feathery border. There is a partial epithelial defect at the central part of the lesion [Figure 1]. Besides AK, fungal keratitis was highly suspected and topical 0.5% levofloxacin and 1% voriconazole each hour were prescribed first. The culture of the scraped corneal tissue was positive for P. aeruginosa and Acanthamoeba 3 days and 6 days later, respectively. The lesion subsided in a week after adding topical chlorhexidine 0.02% each hour [Figure 2]. Except paracentral faint corneal scar, the patient had final best-corrected visual acuity 20/20 in both eyes in 1-month follow-up.
|Figure 1: Dendrite-like anterior stromal infiltration with feathery border was found at the paracentral cornea. The black arrow indicated the site with epithelial defectexclusive|
Click here to view
| Discussion|| |
Biguanides (i.e., polyhexamethylene biguanide and chlorhexidine) and diamidines (i.e., propamidine and hexamidine) are currently available and most often used antiamoebic agents offering both trophozoicidal and cysticidal effects. Recently, an in vitro study shows that voriconazole, an antifungal agent, has good cysticidal effect against Acanthamoeba. Another study even believes that topical voriconazole has better corneal and anterior chamber penetration and lower cellular toxicity on the cornea than topical chlorhexidine. It may be the first drug of choice of atypical AK that presents like fungal keratitis when the culture result cannot be reached.
Endosymbiont bacteria has been known to exist in Acanthamoeba hosts and influence Acanthamoeba virulence, AK clinical features, and susceptibility to antiamoebic drugs., Iovieno et al. found Acanthamoeba hosting bacterial endosymbionts in half of AK patients. Half of AK patients with endosymbiont belonged to the genus Pseudomonas. Previously, it was assumed that P. aeruginosa and Acanthamoeba were mutually exclusive ocular pathogens. However, in vitro studies have showed that Pseudomonas can increase the resistance of Acanthamoeba to contact lens disinfecting solutions and create a biofilm on contact lens surface enhancing Acanthamoeba retention. The presence of the endosymbiont may modify Acanthamoeba phenotype making the protozoa more pathogenic or resistant to therapy. Changes in gene expression and protein profiles have also been observed resulting from the amoeba/bacteria interaction in Hartmannella. Nakagawa et al. found that the presence of bacteria is essential and a critical number of bacteria is required for the development of AK. The time of coexistence with bacteria may also be an important determinant of the severity of AK. Besides, cases of contact lens-related microbial keratitis caused by P. aeruginosa which presented with perineural infiltrates, a typical characteristic of AK, were also reported. It is thus reasonable to use topical levofloxacin in suspected AK patients before the acquirement of culture result. In our case, topical levofloxacin and voriconazole were chosen as the first line treatment. We added topical chlorhexidine after the culture results showed P. aeruginosa and Acanthamoeba. Ortillés et al. found that combined chlorhexidine, voriconazole, and ciprofloxacin showed the greatest amoebicidal activity in vitro although monotherapy may still have its effects. The lesion in our case subsided in 1 week after the adding of topical chlorhexidine.
| Conclusion|| |
Both P. aeruginosa and Acanthamoeba are potentially devastating causes of infectious keratitis. Our case highlights the importance of considering the possibility of a concurrent infection and atypical presentation in cases with contact lens-related keratitis. Topical voriconazole should be considered as the first-line treatment for patients with AK suspected of fungal keratitis. The use of topical levofloxacin cannot only control Pseudomonas but also help to treat Acanthamoeba in such patients who are already under antiamoebic treatments.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.
The authors would like to thank Shih-I Li for supporting the laboratory diagnosis of Acanthamoeba keratitis.
Financial support and sponsorship
Conflicts of interest
The authors declare that there are no conflicts of interests of this paper.
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[Figure 1], [Figure 2]