Acanthamoeba spp. in Contact Lenses from Healthy Individuals from Madrid, Spain.

Thiago Dos Santos Gomes,Sara Bueno,Fernando Redondo,Santiago Angulo,Carmen Del Aguila,Fernando Izquierdo,Lucianna Vaccaro,Angela Magnet,Soledad Fenoy,Carolina Hurtado,Maria Luisa Sánchez,Graham R Wallace

doi:10.1371/journal.pone.0154246

Abstract

PurposeAcanthamoeba keratitis (AK) is a painful and potentially blinding corneal infection caused by Acanthamoeba spp. In Madrid, environmental studies have demonstrated a high presence of these free-living amoebae in tap water. Since most of AK cases occur in contact lenses (CL) wearers with inadequate hygiene habits, the presence of Acanthamoeba in discarded CL has been studied and compared with other common etiological agents of keratitis, such as Pseudomonas aeruginosa and Staphylococcus aureus.MethodsOne hundred and seventy-seven healthy individuals from Madrid contributed their discarded CL and answered a questionnaire on hygiene habits. DNA was extracted from the CL solution and analyzed by real-time PCR for Acanthamoeba, Pseudomonas aeruginosa and Staphylococcus aureus. These CL and their solutions were also cultured on non-nutrient agar to isolate Acanthamoeba.ResultsAmong the 177 samples, Acanthamoeba DNA was detected in 87 (49.2%), P. aeruginosa DNA in 14 (7.9%) and S. aureus DNA in 19 (10.7%). Cultivable amoebae, however, were observed in only one sample (0.6%). This isolate was genotyped as T4. The habits reported by this CL owner included some recognized risk factors for AK, but in this study only the practice of “not cleaning the CL case” presented some statistical significant association with Acanthamoeba DNA presence. Detection of the investigated bacterial DNA did not demonstrate statistical significant association with the studied practices, but the presence of P. aeruginosa revealed a possible inhibition of Acanthamoeba in these samples.ConclusionsThe PCR results suggest a high presence of Acanthamoeba spp. in healthy CL wearers from Madrid, but we can assume that CL solutions are properly disinfecting the CL since only 1.1% of the positive PCR samples correspond to viable amoebae and, after four years, only one participant reported stronger ocular problems. Nevertheless, more studies are necessary to corroborate this hypothesis.

Highlights

The free-living amoebae Acanthamoeba are ubiquitous in nature and have been isolated from soil, dust, air, seawater, swimming pools, sewage, sediments, air-conditioning units, domestic tap water, bottled water, dental treatment units, hospitals, dialysis apparatus, eyewash stations, contact lenses as well as their lens cases and as contaminants in bacterial, yeast and mammalian cell cultures [1, 2].This genus comprises more than 21 species, a classification that has lately been shown to be inconsistent because correlation between binomial classification and molecular typing is, in most cases, not concordant
The habits reported by this Contact lens (CL) owner included some recognized risk factors for Acanthamoeba keratitis (AK), but in this study only the practice of “not cleaning the CL case” presented some statistical significant association with Acanthamoeba DNA presence
Detection of the investigated bacterial DNA did not demonstrate statistical significant association with the studied practices, but the presence of P. aeruginosa revealed a possible inhibition of Acanthamoeba in these samples

Summary

Introduction

The free-living amoebae Acanthamoeba are ubiquitous in nature and have been isolated from soil, dust, air, seawater, swimming pools, sewage, sediments, air-conditioning units, domestic tap water, bottled water, dental treatment units, hospitals, dialysis apparatus, eyewash stations, contact lenses as well as their lens cases and as contaminants in bacterial, yeast and mammalian cell cultures [1, 2]. This genus comprises more than 21 species, a classification that has lately been shown to be inconsistent because correlation between binomial classification and molecular typing is, in most cases, not concordant. CL wearers with poor hygiene practices, one of the recognized risk factors, as well as failure to comply with the recommended cleaning and disinfection procedures, rinsing with tap water or homemade saline solutions, showering while wearing lenses and the overuse of disposable CL are at higher risk for eye infections [12,13,14,15]

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