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 10(7) UFC/mL and belonged to individuals who had not taken sufficient care with hand washing.

Between May 2006 and March 2007, 65 water samples were collected from both heated and unheated swimming pools in the city of Porto Alegre, the capital of the Brazilian state of Rio Grande do Sul. The aim was to explore the problem posed by, and the pathogenic potential of, Acanthamoeba in the pools. Free-living amoebae in the samples were isolated by culture with Escherichia coli and identified from trophozoite and cyst morphology and the results of a PCR with Acanthamoeba-specific oligonucleotide primers. Potential pathogenicity was assessed in osmotolerance and thermotolerance assays. Thirteen (20%) of the water samples investigated were found positive for free-living amoebae, all identified as belonging to morphological groups II (nine isolates) or III (four isolates) of the genus Acanthamoeba. All 13 isolates were found positive in the Acanthamoeba-specific PCR, and the results of the tolerance assays indicated that five (38%) of the isolates should be considered potentially pathogenic. The results of this first study on the occurrence and distribution of Acanthamoeba in the water of swimming pools in Porto Alegre confirm the presence of potentially pathogenic types that may present a risk to human health.

A new method of storage of the free-living amoeba, Acanthamoeba, is described. For this purpose, strips of filter paper were impregnated with cysts of amoebas cultivated axenically and transferred into a cryotube. The strips were dehydrated at 30 degrees C for 24 h and after storage at room temperature. The amoeba viability has been evaluated and the cysts remain viable and pure for at least 1 year. Then, our method has been efficient for the storage of cysts during the evaluated period.