Dr. Murai Éva - Gubányi András szerk.: Parasitologia Hungarica 28. (Budapest, 1995)

for several years and are regularly isolated from natural waters, inadequately treated swimming pools, soil, freshwater fishes, brackish water, ocean sediments, dust, air, and even from bottled mineral water (Sawyer et al. 1977, Brown et al. 1982, Franke and Mackievicz 1982,Kyle and Noblet 1986,). This normally free-living organism occasionally appears as an opportunist parasite of man (Cerva 1981). Acanthamoeba may sometimes occur as a commensalist in the nasopharynx of apparently healthy normal humans (Rivera et al. 1984) and of patients with possible virus infection, and it is not infrequently found in tissue cultures used for virus isolation from nasal swabs (Griffin 1978). Acanthamoeba spp have been reported from the central nervous system (CNS), corneal ulcers, the genitourinary tract and many other sites of the human body (Wang and Feldman 1967, Carter 1972, Ashton and Stamm 1975, Lund 1978, Key et al. 1980, Cerva 1981, Samples et al. 1984, Cohen et al. 1985, Moore et al. 1986, Epstein et al. 1986, Ormerod and Smith 1986, Cohen et al. 1987, Mathers et al. 1987, Moore et al. 1987, Koenig et al. 1987, Silvany et al. 1987, Stehr-Green et al. 1987, Lindquist 1988, Brandt 1989, Stehr-Green 1989). There are a number of published cases that emphasize the need for clinicians to consider acanthamoebic infection in the differential diagnosis of eye infections that fail to respond to antibacterial, antifungal or antiviral therapy (Ma et al. 1981, Hirst et al. 1984, Cohen et al. 1985, Moore et al. 1985, Mannis et al. 1986). These infections are often due to direct eye exposure to contaminated materials or solutions. We have isolated Acanthamoeba spp from a commercial contact lens cleaning-disinfecting solution, from the corneal scrapings of a patient with severe eye soreness, and from the environment. The taxonomy of these small amoeba species is not well established. Consequently, little is known about the relationship between pathogenic and nonpathogenic strains. Several studies report on the analysis of mtDNA variation in members of the genus Acanthamoeba as an aid in taxonomy (Bogler et al. 1983, Byers et al. 1983, Costas et al. 1983, Yagita and Endo 1990). This method has proved to be a useful approach to studying the evolutionary relationship among closely related organisms (Brown and Simpson 1981, Yonekawa et al. 1981). We used the RFLP analysis (Yagita and Endo 1990) for the typing of Acanthamoeba isolates from man and from the environment (CI, Dun, Mos) and for comparing them with human isolates from different countries other than Hungary. MATERIALS AND METHODS Isolation and culture of Acanthamoeba Preparation of agar plates: Non-nutrient agar plates are prepared by pouring 12-15 ml of sterile 1.5% agar in water, into 90 mm diameter Petri dishes. When the agar has hardened, the plates are stored at 4 0 C. The agar plates can be safely stored for 2-3 weeks. Prior to use, the plates are placed in a 37 °C incubator for 30 min. A thin suspension of heat-treated (60 °C for 60 min) Enterobacter aerogenes or Escherichia coli DH1 that does not contain bacterial plasmid is spread onto the surface of the agar. The agar plates coated with bacteria are dried in air under axenic conditions. PYG medium (pH 7) for axenic culture: Proteose-peptone (Difco) 10 g, Yeast extract (Difco) 10 g, NaCl 5 g, 0.5 M Na2HP04 10 ml, 0.5 M KH2PO4 10 ml, distilled water