Identificação morfológica e molecular de amebas de vida livre isoladas em poeira de ar condicionado de uma UTI pediátrica em um hospital escola no interior do Rio Grande do Sul.

Abstract

The free-living amoebae (AVL) are unicellular protozoa, distributed in the most varied habitats, capable of surviving in extreme conditions of temperature and pH. Among the main genera of AVL are Acanthamoeba spp., Naegleria spp. and Balamuthia spp., being considered potentially pathogenic to humans and animals, leading to severe cases of amoebic keratitis and primary amoebic meningoencephalitis. The feeding of these amoebas occurs through phagocytosis and is mainly based on bacteria, but when these are resistant to the process of phagocytosis the AVL can be shelter for the bacteria, encouraging the replication of these. The objective of the study was to determine the presence of AVL in air conditioning dust samples from the pediatric ICU of a School Hospital in the city of Santa Cruz do Sul. Monoxenic cultures were performed, and the samples were sown on non-nutrient agar covered with Escherichia suspension coli and incubated for 10 days with daily verification of amebic growth and observation under optical microscope to perform the peaks of the samples. Morphological identification was based on the type of movement, size and characteristics of cysts and trophozoites according to Page (1988). For the identification of Naegleria spp., The exflagelation test was performed, which is specific for the genus. Osmotolerance and thermotolerance tests were performed in order to identify the pathogenic potential of the isolated samples. Molecular identification was performed by PCR (Polymerase Chain Reaction) using specific primers for Acanthamoeba. Of the 74 samples collected, 67.56% were AVL positive. There was no identification of potentially pathogenic isolates. The genus identified was Acanthamoeba spp. The isolates identified as Acanhtamoeba spp. were compatible with group II according to Page's criteria. Isolated AVLs had no pathogenic potential.