The first case was 7-month-old immunodeficiency girl in whom the diagnosis of Acanthamoeba pneumonia was established by culture of a bronchial washing. The patient had been ill for a month when she was admitted due to neonatal thrombocytopenia with respiratory difficulty and treated with gammaglobulin and steroid. Her chest X-ray showed diffuse alveolar consolidation on the left lung with interstitial hazziness and a partial sign of hyperinflation on the right lung. Laboratory tests showed that the Candida antigen was negative and Pneumocystis carinii was not detected. Mycoplasma antigen was negative. All the immunoglobulin levels (IgG, IgA, IgM) were below the normal range. Five days later the patient expired. The second case was an immunosuppressed 7-year-old boy in whom Acanthamoeba trophozoites were found in the skin biopsy, followed by meningitis leading to death. About five days after a laceration on the region of the left eyebrow, a painful bean-sized nodule developed at the suture site and it was treated with antibiotics and corticosteroid. The skin biopsy showed severe inflammatory cell infiltration. Trophozoites were scattered near the blood vessels throughout the inflammatory zone. From one weak prior to admission, the patient had suffered from vomiting, indigestion and mild fever. Skin nodules with tenderness appeared all over his body surface. Examination of cerebrospinal fluid showed clear, Gram stain was negative, bacterial culture negative, India ink preparation negative, and organism on wet smear negaive. On admission day 10, focal seizure of the left extremity occurred. Brain CT revealed calcific density on the left parietal lobe area and hypodensity on the left basal ganglia. He became comatous and died immediately after discharge. Until now in Korea, two cases that are described in this paper, one Acanthamoeba meningoencephalitis case and seven Acanthamoeba keratitis cases including two unreported keratitis cases that are reported in this paper have been presented.
Acanthamoeba*/isolation & purification ; Amebiasis*/parasitology ; Animal ; Case Report ; Child ; Female ; Human ; Immunocompromised Host ; Infant ; Korea ; Male ; Meningitis/parasitology* ; Pneumonia/parasitology*

After morphological grouping of Acanthamoeba by Pussard and Pons, phylogeny of the genus has been always a big topic to the researchers. Because of the variability of morphological characteristics, unchangeable and stable characters have been investigated for phylogenic criteria. Isoenzyme and mitochondrial DNA RFLP (Mt DNA RFLP) analyses revealed different patterns among strains assigned to a same species. Therefore, these characteristics would be considered as tools for strain discrimination than species identification. The most recently developed and the most promising method is the sequence analysis of 18s ribosomal RNA coding DNA (18s rDNA). The phylogenic tree based on comparison of 18s rDNA sequences distinguished the 3 morphological groups of Acanthamoeba and divided them into 12 unique sequence types (T1-T12 genotypes). Most clinical and environmental isolates belonged to the morphological group II and the genotype T4. In the Republic of Korea, 2 strains of Acanthamoeba, YM-2 and YM-3, were first isolated from the environment in 1974. However, phylogenic identification of Korean Acanthamoeba isolates from human infections or the environment were tried from the late 1990s. By RFLP analysis or total sequence analysis of 18s rDNA revealed that almost all clinical isolates including the one from a suspicious granulomatous amebic encephalitis patient belonged to the genotype T4. A large number of environmental isolates from contact lens storage cases, tapped water, and ocean sediments also belonged to the genotype T4. Almost identical strain characteristics, such as Mt DNA RFLP pattern of environmental isolates, with the clinical isolates could make a simple conclusion that most environmental isolates might be a potential keratopathogen.
Acanthamoeba/*classification/genetics/*isolation & purification ; Amebiasis/parasitology ; DNA, Protozoan/genetics ; DNA, Ribosomal/genetics ; Humans ; Molecular Sequence Data ; *Phylogeny ; Soil/parasitology ; Water/parasitology

Strongyloides stercoralis (SS) is an intestinal nematode that is mainly endemic in tropical and subtropical regions and sporadic in temperate zones. SS infection frequently occurs in people who have hematologic malignancies, HIV infection and in individuals undergoing immunosuppressive therapy. In this study, we report a 12- year-old immunocompetent boy who was admitted to our hospital with acute abdomen. Laboratory evaluation showed strongyloidiasis, amebiasis and giardiasis. Clinical and laboratory findings immediately improved with albendazole therapy. Therefore, when diarrhea with signs of acute abdomen is observed, stool examinations should be done for enteroparasitosis. This approach will prevent misdiagnosis as acute abdomen. Complete clinical improvement is possible by medical therapy without surgical intervention.
Abdomen, Acute/*etiology ; Amebiasis/*complications ; Animals ; Child ; Giardiasis/*complications ; Humans ; Immunocompetence ; Male ; *Strongyloides stercoralis ; Strongyloidiasis/*complications/parasitology

A survey was carried out from August to December 2004 in Pusan, Korea to document the presence of free-living amoeba (FLA), including the genus Acanthamoeba, in both contact lens storage cases and domestic tap water. Acanthamoeba was isolated from 5 (4.2%) in 120 contact lens storage cases. Four house tap water samples from residents, whose contact lens storage cases had been contaminated by Acanthamoeba, were also found to be contaminated with Acanthamoeba. Therefore, the contamination rate of FLA and Acanthamoeba in domestic tap water was investigated in order to examine the role of domestic tap water in Acanthamoeba contamination of contact lens storage cases. FLA and Acanthamoeba were identified in 97 (46.8%) and 16 (7.7%) of the 207 domestic tap water samples, respectively. There were no significant differences between the contamination rates of FLA in tap water according to the filtration plant of origin. No FLA was detected in the tap water directly supplied by the water purification plants. Water storage tanks appear to promote FLA colonization, including Acanthamoeba, in domestic tap water. This increases the risk of Acanthamoeba contamination in contact lens storage cases as well as increasing the risk of Acanthamoeba keratitis.
Acanthamoeba/*isolation & purification ; Amebiasis/epidemiology ; Animals ; Comparative Study ; Contact Lenses/parasitology ; Data Collection ; Humans ; Korea/epidemiology ; Research Support, Non-U.S. Gov't ; Risk Factors ; Water/*parasitology ; Water Supply/*standards

A new species of Acanthamoeba was isolated from a freshwater fish in Korea and tentatively named Acanthamoeba sp. YM-4 (Korean isolate YM-4). The trophozoites were 11.0-23.0 micrometer in length and had hyaline filamentous projections. Cysts were similar to those of A. culbertsoni and A. royreba, which were previously designated as Acanthamoeba group III. Acanthamoeba YM-4 can survive at 40 degrees C, and its generation time was 19.6 hr, which was longer than that of A. culbertsoni. In terms of the in vitro cytotoxicity of lysates, Acanthamoeba YM-4 was weaker than A. culbertsoni, but stronger than A. polyphaga. On the basis of the mortality of experimentally infected mice, Acanthamoeba YM-4 was found to be highly virulent. The isoenzymes profile of Acanthamoeba YM-4 was similar to that of A. royreba. An anti-Acanthamoeba YM-4 monoclonal antibody, McAY7, was found to react only with Acanthamoeba YM-4, and not with A. culbertsoni. Random amplified polymorphic DNA marker analysis and RFLP analysis of mitochondrial DNA and of 18S small subunit ribosomal RNA, placed Acanthamoeba YM-4 in a separate cluster on the basis of phylogenetic distances. Thus the Acanthamoeba Korean isolate YM-4 was identified as a new species, and assigned as Acanthamoeba sohi.
Acanthamoeba/*classification/genetics/isolation & purification/*pathogenicity ; Amebiasis/parasitology/*veterinary ; Animals ; DNA, Mitochondrial/analysis ; DNA, Protozoan/analysis ; Fish Diseases/*parasitology ; Gills/parasitology ; Goldfish/*parasitology ; Korea ; Mice ; Phylogeny ; Polymorphism, Restriction Fragment Length ; RNA, Ribosomal, 18S/genetics ; Random Amplified Polymorphic DNA Technique ; Virulence

After bathing at a hot spring resort, a 75-year-old man presented to the emergency department because of seizure-like attack with loss of conscious. This is the first case of primary amebic meningoencephalitis (PAM) caused by Naegleria fowleri in Taiwan. PAM was diagnosed based on detection of actively motile trophozoites in cerebrospinal fluid using a wet-mount smear and the Liu's stain. The amoebae were further confirmed by PCR and gene sequencing. In spite of administering amphotericin B treatment, the patient died 25 days later.
Aged ; Amebiasis/*diagnosis/parasitology/*pathology ; Central Nervous System Protozoal Infections/*diagnosis/parasitology/*pathology ; Cerebrospinal Fluid/parasitology ; DNA, Protozoan/chemistry/genetics ; Fatal Outcome ; Humans ; Male ; Microscopy ; Naegleria fowleri/classification/genetics/*isolation & purification ; Polymerase Chain Reaction ; Sequence Analysis, DNA ; Taiwan

Randomly selected 435 clones from Acanthamoeba healyi cDNA library were sequenced and a total of 387 expressed sequence tags (ESTs) had been generated. Based on the results of BLAST search, 130 clones (34.4%) were identified as the genes encoding surface proteins, enzymes for DNA, energy production or other metabolism, kinases and phosphatases, protease, proteins for signal transduction, structural and cytoskeletal proteins, cell cycle related proteins, transcription factors, transcription and translational machineries, and transporter proteins. Most of the genes (88.5%) are newly identified in the genus Acanthamoeba. Although 15 clones matched the genes of Acanthamoeba located in the public databases, twelve clones were actin gene which was the most frequently expressed gene in this study. These ESTs of Acanthamoeba would give valuable information to study the organism as a model system for biological investigations such as cytoskeleton or cell movement, signal transduction, transcriptional and translational regulations. These results would also provide clues to elucidate factors for pathogenesis in human granulomatous amoebic encephalitis or keratitis by Acanthamoeba.
Acanthamoeba/cytology/*genetics/pathogenicity ; Amebiasis/parasitology ; Animals ; DNA, Protozoan/*genetics ; *Expressed Sequence Tags ; Gene Library ; Human ; Protozoan Proteins/genetics ; *Sequence Analysis, DNA ; Signal Transduction ; Support, Non-U.S. Gov't

Acanthamoeba cysts are resistant to unfavorable physiological conditions and various disinfectants. Acanthamoeba cysts have 2 walls containing various sugar moieties, and in particular, one third of the inner wall is composed of cellulose. In this study, it has been shown that down-regulation of cellulose synthase by small interfering RNA (siRNA) significantly inhibits the formation of mature Acanthamoeba castellanii cysts. Calcofluor white staining and transmission electron microscopy revealed that siRNA transfected amoeba failed to form an inner wall during encystation and thus are likely to be more vulnerable. In addition, the expression of xylose isomerase, which is involved in cyst wall formation, was not altered in cellulose synthase down-regulated amoeba, indicating that cellulose synthase is a crucial factor for inner wall formation by Acanthamoeba during encystation.
Acanthamoeba castellanii/*enzymology/genetics/metabolism ; Aldose-Ketose Isomerases/*biosynthesis ; Amebiasis/*pathology ; Benzenesulfonates ; Cell Wall/chemistry/genetics/*metabolism ; Cellulose/biosynthesis ; Down-Regulation ; Encephalitis/parasitology ; Glucosyltransferases/*biosynthesis/genetics ; Keratitis/parasitology ; Microscopy, Electron, Transmission ; RNA Interference ; RNA, Small Interfering

Acanthamoeba spp. are single-celled protozoan organisms that are widely distributed in the environment. In this study, to understand functional roles of a mannose-binding protein (MBP), Acanthamoeba castellanii was treated with methyl-alpha-D-mannopyranoside (mannose), and adhesion and cytotoxicity of the amoeba were analyzed. In addition, to understand the association of MBP for amoeba phagocytosis, phagocytosis assay was analyzed using non-pathogenic bacterium, Escherichia coli K12. Amoebae treated with mannose for 20 cycles exhibited larger vacuoles occupying the most area of the amoebic cytoplasm in comparison with the control group amoebae and glucose-treated amoebae. Mannose-selected amoebae exhibited lower levels of binding to Chinese hamster ovary (CHO) cells. Exogenous mannose inhibited >50% inhibition of amoebae (control group) binding to CHO cells. Moreover, exogenous mannose inhibited amoebae (i.e., man-treated) binding to CHO cells by <15%. Mannose-selected amoebae exhibited significantly decreased cytotoxicity to CHO cells compared with the control group amoebae, 25.1% vs 92.1%. In phagocytic assay, mannose-selected amoebae exhibited significant decreases in bacterial uptake in comparison with the control group, 0.019% vs 0.03% (P<0.05). Taken together, it is suggested that mannose-selected A. castellanii trophozoites should be severely damaged and do not well interact with a target cell via a lectin of MBP.
Acanthamoeba castellanii/drug effects/metabolism/*pathogenicity ; Amebiasis/*parasitology ; Animals ; CHO Cells ; Cell Adhesion/drug effects ; Cell Survival ; Cricetinae ; Cricetulus ; Escherichia coli K12/metabolism ; Female ; Mannose/*pharmacology ; Mannose-Binding Lectin/*metabolism ; Phagocytosis ; Protozoan Proteins/metabolism

The mature cyst of Acanthamoeba is highly resistant to various antibiotics and therapeutic agents. Cyst wall of Acanthamoeba are composed of cellulose, acid-resistant proteins, lipids, and unidentified materials. Because cellulose is one of the primary components of the inner cyst wall, cellulose synthesis is essential to the process of cyst formation in Acanthamoeba. In this study, we hypothesized the key and short-step process in synthesis of cellulose from glycogen in encysting Acanthamoeba castellanii, and confirmed it by comparing the expression pattern of enzymes involving glycogenolysis and cellulose synthesis. The genes of 3 enzymes, glycogen phosphorylase, UDP-glucose pyrophosphorylase, and cellulose synthase, which are involved in the cellulose synthesis, were expressed high at the 1st and 2nd day of encystation. However, the phosphoglucomutase that facilitates the interconversion of glucose 1-phosphate and glucose 6-phosphate expressed low during encystation. This report identified the short-cut pathway of cellulose synthesis required for construction of the cyst wall during the encystation process in Acanthamoeba. This study provides important information to understand cyst wall formation in encysting Acanthamoeba.
Acanthamoeba castellanii/*enzymology/genetics/growth & development ; Amebiasis/*parasitology ; Cell Wall/*metabolism ; Cellulose/*biosynthesis/genetics ; Glucosyltransferases/genetics/metabolism ; Glycogen Phosphorylase/genetics/metabolism ; Protozoan Proteins/genetics/*metabolism ; UTP-Glucose-1-Phosphate Uridylyltransferase/genetics/metabolism