Acanthamoeba spp. and bacterial contamination in contact lens storage cases and the relationship to user profiles

Abstract

Storage cases for contact lenses receive microbiota from the environment, body, and eye, which can form biofilms. These biofilms, in addition to causing discomfort and cloudy vision, can cause local irritation, facilitate the adherence of microorganisms, and lead to infection. The objective of this study was to evaluate the presence of bacteria and Acanthamoeba spp. in the biofilm and solutions in contact lens storage cases, and to assess their relationships to the habits of contact lens wearers. Eighty-one volunteers assembled from the ophthalmology section of a public hospital and from the Central Campus of the federal university, both in the state of Rio Grande do Sul, Brazil, provided the contact lens storage cases. The samples collected were inoculated into sheep blood agar, to isolate bacteria; and into 1.5% non-nutrient agar with an overlayer of Escherichia coli, to isolate free-living amoebas. Of the 81 samples analyzed, 58 (71%) showed bacterial growth and seven (8.6%) were positive for Acanthamoeba spp. The amoebas were identified according to the morphological criteria of Page (A new key to fresh water and soil gymnamoebae, Freshwater Biology Association, Ambleside, UK, 1988) and confirmed by PCR. The storage cases that were positive for Acanthamoeba spp. had a mean of 10⁷ UFC/mL and belonged to individuals who had not taken sufficient care with hand washing.