Characterization of Acanthamoeba Isolated from Swimming Pools and Farmlands
Date Issued
2012
Date
2012
Author(s)
Chang, Wei-Chen
Abstract
Acanthamoeba is free-living amoebae and ubiquitous in a wide variety of natural habitats and human-made environments, including water, soil, and air, and a opportunistically pathogenic organism that can cause a severe sight-threatening Acanthamoeba keratitis (AK), and a fatal infection of the central nervous system (granulomatous amoebic encephalitis, GAE), mortality rate can up to 90%. The mechanisms associated with the pathogenesis of Acanthamoeba tend to be highly complex, depending on parasite, host and the environmental factors. Besides, these amoebae are not only infective to human but also the hosts for other pathogenic bacteria to multiply in the environments.
In this study, we isolated and characterized Acanthamoeba from water, soils, and air in the effort to determine the presence and potentially pathogenic Acanthamoeba. There were 12 water samples from 6 chlorinated swimming pools in Taipei city, 13 soil samples and 14 air samples were from 6 onion farmlands in Hengchun Township, Pingtung County and 5 onion farmlands in Checheng Township, Pingtung County. The samples were then followed by morphology and molecular identification, phylogenetic and physiologically assays including thermotolerance and osmotolerance characterization. Environmental factors in water samples including pH, water temperature, conductivity, turbidity, hardness, dissolved oxygen, free chlorine, salinity, total dissolved solids and heterotrophic plate count. Water content, temperature and heterotrophic plate count in soil samples. Temperature, wind velocity and relative humidity in air were measured in order to characterize the sampling sites and to determine how these factors affecting the potentially pathogenicity of isolated Acanthamoeba by genotyping, thermotolerance and osmotolerance.
In the present study, we discovered Acanthamoeba in six swimming pools (100%), 13 onion farmlands (100%), and only three out of 14 air samples (21.43%). Total 42 isolates of Acanthamoeba are isolated, 26 isolates from swimming pools, 13 isolates from soil, and three isolates from air samples. The 26 isolates in swimming pools are belong to Acanthamoeba polyphaga, and genotype T4, there are 12 isolates taken into thermotolerance and osmotolerance among all, only one isolate from NEIHU swimming pool cannot growth under 37oC, and 12 isolates cannot growth under 42oC and 52oC, in osmotolerance, 12 isolates can tolerant and growth up to 1 M mannitol.
In 13 soil isolates, six isolates belong to Acanthamoeba polyphaga and genotype T4, and the rest 7 isolates belong to Acanthamoeba lenticulata, genotype T5, all 13 isolates were testing for the thermotolerance and osmotolerance, 7 isolates can tolerant up to 52oC, two isolates growth under 42oC, and only four isolates growth at 37oC, and 13 isolates cannot growth at 1 M mannitol, but can growth at 0.5 M mannitol.
In three air isolates, two isolates belong to Acanthamoeba polyphaga and genotype T4, one isolate belongs to Acanthamoeba species, genotype T15, all three isolates were testing for the thermotolerance and osmotolerance, the 2 isolates can growth at 37oC besides isolate in HENGCHUN onion farmlands 4, which cannot growth at 37oC, three isolates cannot growth under 42oC and 52oC, when it comes to osmotolerance, only one isolate can growth under 0.5 M mannitol and 1 M mannitol, one isolate can growth under 0.5 M mannitol, and the other isolate cannot growth neither 1 M mannitol nor 0.5 M mannitol.
The pathogenicity based on genotyping, thermotolerance and osmotolerance revealed the all isolates from swimming pools in present study are genotype T4 and among the 12 isolates with thermotolerance and osmotolerance, 11 isolates can grew at 37oC and 1 M mannitol. Once the pool isolates contact with human eyes, they can tolerate body temperatures and osmolarity of tear film. Most of 16 isolates from soil and air samples indicated weak pathogenicity since these isolates cannot growth under 1 M mannitol. Acanthamoeba isolates from swimming pools indicated higher potentially pathogenicity while the potential risk on isolates from soils since isolates can withstand at higher temperature.
Subjects
Acanthamoeba
keratitis
granulomatous amebic encephalitis
pathogenicity
environmental factors
biological indicator
genotype
thermotolerance
osmotolerance
SDGs
Type
thesis
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