Morphological Features and In Vitro Cytopathic Effect of Acanthamoeba griffini Trophozoites Isolated from a Clinical Case.

Light and transmission electron microscopy observations are reported on the structure and in vitro cytopathic effect of Acanthamoeba griffini trophozoites isolated from a clinical case. Live trophozoites were moderately active with a remarkable pleomorphism which changed from ovoid to quite elongated shapes. When moving, amoebae formed cytoplasmic projections such as wide lamellae and acanthopodia of diverse size and thickness which contain a significant amount of actin. Ultrastructurally, the cytoplasm showed the main organelles found in other free-living amoebae. Coincubation of trophozoites with MDCK cell monolayers resulted in a local damage to target cells after 24 h of interaction, suggesting that the cytopathic effect is contact-dependent. By transmission electron microscopy, amoebae appeared to engulf small portions of the MDCK cells; however, the cells that were not in contact with trophozoites had an unaltered morphology. When epithelial monolayers were incubated with conditioned medium for 24 h, small areas of cell injury were also observed. The phylogenetical analysis as well as the sequencing of the acquired amplified product for the DF3 region of the amoebae isolate confirmed that it belongs to genotype T3, which includes other pathogenic amoebae; besides the activity of two drugs currently used against Acanthamoeba was tested on A. griffini.

Voriconazole as a first-line treatment against potentially pathogenic Acanthamoeba strains from Peru.

Pathogenic strains of Acanthamoeba genus are the causative agents of fatal granulomatous amoebic encephalitis and a serious sight-threatening infection of the eye known as Acanthamoeba keratitis. In a previous study, Acanthamoeba strains were isolated from nasal swabs collected from healthy individuals in Peru. In the present study, the pathogenic potential of the isolated strains was established based on temperature and osmotolerance assays as well as the secretion rate of extracellular proteases. Based on these experiments, four strains that showed the highest pathogenic potential were selected for sensitivity assays against two molecules (voriconazole and chlorhexidine) which are currently used for the treatment of Acanthamoeba infections. After performing sensitivity and activity assays, it was found that both drugs were active against the tested strains. However, voriconazole showed higher activity against the studied strains compared to chlorhexidine. Therefore, voriconazole should be established as a first-line treatment against Acanthamoeba infections at least in the studied region of Peru.

Acanthamoeba belonging to T3, T4, and T11: genotypes isolated from air-conditioning units in Santiago, Chile.

Free-living amoebae (FLA) of the genus Acanthamoeba are widely distributed in the environment, in the air, soil, and water, and have also been isolated from air-conditioning units. The objective of this work was to investigate the presence of this genus of FLA in the air-conditioning equipment at the Institute of Public Health of Chile in Santiago, Chile. Water and air samples were collected from air-conditioning systems and were checked for the presence of Acanthamoeba spp. Positive samples were further classified at the genotype level after sequencing the highly variable diagnostic fragment 3 (DF3) region of the 18S rRNA gene. This is the first report of the T3, T4, and T11 genotypes of Acanthamoeba in air-conditioning units from Chile. Overall, the widespread distribution of potentially pathogenic Acanthamoeba strains in the studied source demands more awareness within the public and health professionals in Chile as this pathogen is emerging as a risk for human health worldwide.