Investigating Domestic Shower Settings as a Risk Factor for Acanthamoeba Keratitis

Binod Rayamajhee,Jacqueline Tan,Mark Willcox,Ajay Vijay,Jamie (Jung Yun) Kim,Dinesh Subedi,Fiona L Henriquez,Seoyoung Won,Nicole A Carnt

doi:10.3390/w12123493

Binod Rayamajhee, Jacqueline Tan + Show 7 more

Open Access

https://doi.org/10.3390/w12123493

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Abstract

Acanthamoeba keratitis (AK) is a sight-threatening infection of the cornea, which is caused by soil and the waterborne protist Acanthamoeba spp. AK most commonly occurs during contact lens (CL) wear. Risk factors for AK have been linked to non-optimal lens hygiene practices and Acanthamoeba contamination of domestic water. This study investigated the prevalence of Acanthamoeba species in domestic showers in the greater Sydney region, as well as the perception of water contamination of CL as being a risk factor for AK among previous AK patients and their family and friends. Samples from four locations of 13 participants’ shower areas were cultured and Acanthamoeba 18S rRNA was amplified by PCR, followed by sequencing. Twenty-six responses were received to the online questionnaire. Fifteen water samples (29%, 15/52) contained amoeba that were morphologically classified as Acanthamoeba spp. PCR amplification confirmed the presence of Acanthamoeba spp. in four samples (8%, 4/52). Three isolates belonged to the T4, and one isolate to the T3 genotype. On the questionnaire survey, 96% (25/26) of respondents believed that water contamination was likely to be a risk factor for Acanthamoeba keratitis and 58% rated showering with CL as ‘extremely likely’ to be a risk factor for AK. Acanthamoeba pathogenic genotypes (T3 and T4) in the domestic bathroom water suggest that clinicians should remain vigilant in educating CL wearers about avoiding domestic water contamination of CL.

Highlights

Acanthamoeba is an amphizoic amoeba with two distinct life stages: an active trophozoite and a dormant cyst
The current study investigated whether contact lens (CL) wearers who developed Acanthamoeba keratitis (AK) and their family and friends were aware of the risk of tap water exposure to CL
Phase I of the study included a survey of previous AK. Patients and their family and friends, and phase II evaluated the prevalence of Acanthamoeba species in domestic bathroom water samples

Summary

Introduction

Acanthamoeba is an amphizoic amoeba with two distinct life stages: an active trophozoite and a dormant cyst. Acanthamoeba is found in diverse ecological habitats such as soil, sewage, domestic water supplies, bathtubs, ponds and air conditioning systems [1,2]. It can survive for prolonged periods as stress-resistant double walled cysts, which can excyst to form trophozoites when a suitable condition returns [3]. Acanthamoeba is known to cause cutaneous lesions, sinusitis, meningoencephalitis and keratitis [4]. Acanthamoeba keratitis (AK) is a potentially blindness-causing, painful and difficult-to-treat corneal infection [5]. Based on the 18S rRNA nucleotide sequence, Acanthamoeba species are classified into at least 22 genotypes (T1–T22), with most

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