OCCURRENCE OF POTENTIALLY PATHOGENIC SOIL-DWELLING ACANTHAMOEBA ISOLATED FROM RECREATIONAL PARKS OF IRAN

Acanthamoeba spp. are the causative agent of severe diseases such as keratitis and encephalitis. Presence of pathogenic Acanthamoeba in environmental sources such as soil could be a health threat for high-risk people including children, contact lens wearers and immunosuppressed patients. The present study was conducted to address the distribution of Acanthamoeba spp. in soil samples of recreational parks of Tehran, Iran. A total of 52 soil samples of 17 parks in Tehran (north, south, east and west region) have been collected from recreational parks in Tehran, Iran. Identification of Acanthamoeba spp. was based on both morphological criteria and molecular-based approaches. Samples were cultured on 1.5% non-nutrient agar (NNA) overlaid with a layer of heat-killed Escherichia coli. All plates were sealed, incubated at 30°C, and monitored daily for outgrowth of Acanthamoeba. The presence of Acanthamoeba was confirmed by cyst and trophozoite morphology. For further evaluation and for elimination of bacterial and fungal contamination, the cysts were cloned, and subcultured by cutting out a small piece of agar and placing it onto a fresh plate. DNA extraction and PCR were performed using specific primer pairs. Genotype identification was based on the sequencing of Acanthamoeba Specific Amplimer 1 (ASA1). The results revealed that 17.3% of samples were contaminated with Acanthamoeba spp. These samples contain flat-shaped trophozoites and double walled cyst with star shape endocyst. Sequencing of the PCR products revealed that all isolates were belonged to the potentially pathogenic T4 type. Acanthamoeba belonging to this genotype is the most prevalent type causing Acanthamoeba-related infections. Presence of potentially pathogenic Acanthamoeba in soil samples of parks highlights a risk for high risk people as Acanthamoeba-related infections is continue to rise in recent years. Periodical surveillance of such soils and posting of warning sign is recommended to prevent human diseases related with pathogenic Acanthamoeba.