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Parasitology Research Nov 2020Free-living amoeba (FLA) research in the Philippines is still in its infancy but has, by far, demonstrated the presence of potentially pathogenic species. Acanthamoeba...
Free-living amoeba (FLA) research in the Philippines is still in its infancy but has, by far, demonstrated the presence of potentially pathogenic species. Acanthamoeba may cause sight-threatening and central nervous system infections to humans, yet its epidemiologic distribution from local environmental sources is yet to be defined. The present study aimed to provide a baseline epidemiologic distribution of Acanthamoeba spp. in freshwater systems in the Philippines and establish potential pathogenicity of isolates through thermo-tolerance assay. A total of 63 water samples were collected from 13 freshwater systems all over the Philippine archipelago. The low-volume (50 ml) water samples were processed and cultured on non-nutrient agar lawned with Escherichia coli and observed for amoebic growth using light microscopy. Amoebic culture demonstrated 14.28% (9/63) positivity while further molecular testing of culture-positive plates using Acanthamoeba-specific primers demonstrated 100% (9/9) confirmation of Acanthamoeba species. Genotyping of Acanthamoeba isolates revealed T1, T3, T4, T5, T7, T11, and T15 genotypes. Thermo-tolerance assay demonstrated that T5 and T7 genotypes were potentially pathogenic strains. The evidence of environmental distribution of Acanthamoeba spp. in the freshwater systems in the Philippines and thermo-tolerance profile of isolates are significant aspects of amoeba study in public health and calls for initiatives in the dissemination of relevant information and the expansion of knowledge, awareness, and policies on pathogenic waterborne amoeba to mitigate, prevent, detect, and report cases of human infections.
Topics: Acanthamoeba; DNA, Protozoan; Environmental Monitoring; Fresh Water; Genotype; Humans; Philippines; Thermotolerance
PubMed: 32918603
DOI: 10.1007/s00436-020-06874-2 -
The Journal of Eukaryotic Microbiology 2001Since the early 1960s, axenic culture and the development of procedures for the induction of encystation have made Acanthamoeba spp. superb experimental systems for... (Review)
Review
Since the early 1960s, axenic culture and the development of procedures for the induction of encystation have made Acanthamoeba spp. superb experimental systems for studies of cell biology and differentiation. More recently, since their roles as human pathogens causing keratitis and encephalitis have become widely recognized, it has become urgent to understand the parameters that determine differentiation, as cysts are much more resistant to biocides than are the trophozoites. Viability of trophozoites of the soil amoeba Acanthamoeba castellanii (Neff), is conveniently measured by its ability to form plaques on a lawn of Escherichia coli. Use of confocal laser scanning microscopy with Calcofluor white, Congo Red or the anionic oxonol dye, DiBAC4(3) or flow cytometry with propidium iodide diacetate and fluorescein or oxonol provides more rapid assessment. For cysts, the plaque method is still the best, because dye exclusion does not necessarily indicate viability and therefore the plate count method has been used to study the sequence of development of biocide resistance during the differentiation process. After two hours, resistance to HCl was apparent. Polyhexamethylene biguanide, benzalkonium chloride, propamidine isethionate, pentamidine isethionate, dibromopropamine isethionate, and H2O2 and moist heat, all lost effectiveness at between 14 and 24 h after trophozoites were inoculated into encystation media. Chlorhexidine diacetate resistance was observed at between 24 and 36 h. The molecular biology and biochemistry of the modifications that underlie these changes are now being investigated.
Topics: Acanthamoeba; Amebiasis; Amebicides; Animals; Drug Resistance; Humans
PubMed: 11249185
DOI: 10.1111/j.1550-7408.2001.tb00410.x -
Revista Chilena de Infectologia :... Apr 2013Among free-living amoeba in nature, species of the genus Acanthamoeba have been associated with human disease. These amoeba are among the most abundant protozoa in... (Review)
Review
Among free-living amoeba in nature, species of the genus Acanthamoeba have been associated with human disease. These amoeba are among the most abundant protozoa in nature due to its cosmopolitan distribution and are able to survive in a wide variety of habitats because its low demand for food and in harsh environments by forming structures known as cysts. However, ecological changes and incursion of its different habitats have made this organism can invade a host and live as parasites within him. That's why this type of protozoa are known as amphizoic organism, because human can be constituted as its host, causing infections in the central nervous system, disseminated infections in skin and lungs, and keratitis. Thus, since an increase in the number of cases of Acanthamoeba infections has occurred worldwide, these protozoa have become increasingly important as agents of human disease. This review summarizes what is known of this kind of free-living amoeba, focusing on the biology, ecology, pathogenesis, diagnosis, treatment and human defense mechanism against infection by the amoeba.
Topics: Acanthamoeba; Amebiasis; Host-Parasite Interactions; Humans; Opportunistic Infections
PubMed: 23677153
DOI: 10.4067/S0716-10182013000200005 -
Archivum Immunologiae Et Therapiae... 2002Infections of the corneal surface are an important cause of blindness. Protozoal, viral, bacterial, and helminthic infections of the cornea account for up to 9 million... (Review)
Review
Infections of the corneal surface are an important cause of blindness. Protozoal, viral, bacterial, and helminthic infections of the cornea account for up to 9 million cases of corneal blindness. Free-living amoebae of the genus Acanthamoeba produce a progressive infection of the cornea called Acanthamoeba keratitis. Disease is usually transmitted by Acanthamoeba trophozoites bound to soft contact lenses. Infection of the cornea is initiated when the parasite binds to the corneal epithelial surface. Recrudescence can occur and suggests that the adaptive immune response is not aroused by corneal Acanthamoeba infections. Systemic immunization with Acanthamoeba antigens elicits robust Th1 cell-mediated immunity and serum IgG antibody, yet fails to prevent the development of Acanthamoeba keratitis. However, immunization via mucosal surfaces induces anti-Acanthamoeba IgA antibodies in the tears and provides solid protection against the development of Acanthamoeba keratitis. Unlike other immune effector mechanisms that rely on cytolysis, inflammation, release of toxic molecules, or the induction of host cell death, the adaptive immune apparatus prevents Acanthamoeba infections of the cornea by simply preventing the attachment of the parasite to the epithelial surface. The beauty of this mechanism lies in its exquisite simplicity and efficacy.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Animals; Antigens, Protozoan; Cornea; Humans; Immunity, Cellular; Immunity, Mucosal
PubMed: 11916309
DOI: No ID Found -
Scientific Reports Jul 2020Acanthamoeba can cause visually destructive Acanthamoeba keratitis (AK) in contact lens (CL) users. The purpose of this study was to determine whether Acanthamoeba was...
Acanthamoeba can cause visually destructive Acanthamoeba keratitis (AK) in contact lens (CL) users. The purpose of this study was to determine whether Acanthamoeba was present in the CL cases of CL wearers and to develop techniques to prevent the contaminations. To accomplish this, 512 CL case samples were collected from 305 healthy CL wearers. Using real-time PCR, Acanthamoeba DNA was detected in 19.1% of CL cases, however their presence was not directly associated with poor CL case care. Instead, the presence of Acanthamoeba DNA was associated with significant levels of many different bacterial species. When the CL cases underwent metagenomic analysis, the most abundant bacterial orders were Enterobacteriales followed by Burkholderiales, Pseudomonadales, and Flavobacteriales. The presence of Acanthamoeba was characterized by Propionibacterium acnes and Rothia aeria and was also associated with an increase in the α diversity. Collectively, Acanthamoeba contamination occurs when a diversified bacterial flora is present in CL cases. This can effectively be prevented by careful and thorough CL case care.
Topics: Acanthamoeba; Adult; Contact Lenses; DNA, Bacterial; Female; Humans; Hygiene; Male; Middle Aged; Polymerase Chain Reaction; Risk Factors
PubMed: 32724150
DOI: 10.1038/s41598-020-69554-2 -
Experimental Parasitology Apr 2012Acanthamoeba hosts diverse microbial organisms including viruses, bacteria, yeast and protists, some of which are potential human pathogens. The precise nature of this... (Review)
Review
Acanthamoeba hosts diverse microbial organisms including viruses, bacteria, yeast and protists, some of which are potential human pathogens. The precise nature of this symbiosis is not clear, but it is suggested that such interactions enable pathogenic microbes to survive hostile conditions and lead to their transmission to susceptible hosts to establish infection. In particular, Acanthamoeba-bacteria interactions have gained significant attention by the scientific and the medical community and have led to speculations of employing anti-amoebic approaches in eradicating 'superbugs' from clinical settings. Here, we discuss the nature of these convoluted interactions and the benefit they represent for the symbionts.
Topics: Acanthamoeba; Bacteria; Bacterial Infections; Disease Reservoirs; Humans; Symbiosis
PubMed: 22348931
DOI: 10.1016/j.exppara.2012.01.021 -
Annals of Parasitology 2020Acanthamoeba spp. are ubiquitous in both natural and man-made environments and have been isolated in lakes, recreational pools, tap water, and air conditioning systems....
Acanthamoeba spp. are ubiquitous in both natural and man-made environments and have been isolated in lakes, recreational pools, tap water, and air conditioning systems. Twenty surface water (SW) samples were collected from different sampling areas of Lake Buhi. Water samples were pelleted, cultured in NNA lawned with Escherichia coli and observed microscopically. 10% of samples (2/20) were positive for amoebic growth and were furthered tested using molecular techniques. Polymerase chain reaction showed the presence of Acanthamoeba sp. DNA. The presence of potentially pathogenic Acanthamoeba sp. poses a public health concern. The formulation of policies for proper information dissemination and control measures to avert the contraction of pathogenic FLA as well as other WBPP should be seriously considered.
Topics: Acanthamoeba; DNA, Protozoan; Lakes; Philippines; Polymerase Chain Reaction
PubMed: 32199003
DOI: 10.17420/ap6601.245 -
Protist Dec 2016Amoeba often use cell movement as a mechanism to find food, such as bacteria, in their environment. The chemotactic movement of the soil amoeba Dictyostelium to folate...
Amoeba often use cell movement as a mechanism to find food, such as bacteria, in their environment. The chemotactic movement of the soil amoeba Dictyostelium to folate or other pterin compounds released by bacteria is a well-documented foraging mechanism. Acanthamoeba can also feed on bacteria but relatively little is known about the mechanism(s) by which this amoeba locates bacteria. Acanthamoeba movement in the presence of folate or bacteria was analyzed in above agar assays and compared to that observed for Dictyostelium. The overall mobility of Acanthamoeba was robust like that of Dictyostelium but Acanthamoeba did not display a chemotactic response to folate. In the presence of bacteria, Acanthamoeba only showed a marginal bias in directed movement whereas Dictyostelium displayed a strong chemotactic response. A comparison of genomes revealed that Acanthamoeba and Dictyostelium share some similarities in G protein signaling components but that specific G proteins used in Dictyostelium chemotactic responses were not present in current Acanthamoeba genome sequence data. The results of this study suggest that Acanthamoeba does not use chemotaxis as the primary mechanism to find bacterial food sources and that the chemotactic responses of Dictyostelium to bacteria may have co-evolved with chemotactic responses that facilitate multicellular development.
Topics: Acanthamoeba; Chemotaxis; Dictyostelium; Phylogeny; Protozoan Proteins; Signal Transduction
PubMed: 27693864
DOI: 10.1016/j.protis.2016.08.006 -
The Journal of Infection Apr 2001
Topics: Acanthamoeba; Acanthamoeba Keratitis; Amebiasis; Animals; Diagnosis, Differential; Hartmannella; Humans
PubMed: 11545559
DOI: 10.1053/jinf.2001.0826 -
Japanese Journal of Infectious Diseases May 2021Acanthamoeba are free-living amoebae that cause granulomatous amoebic encephalitis and keratitis. In this study, we aimed to isolate and identify Acanthamoeba from air...
Acanthamoeba are free-living amoebae that cause granulomatous amoebic encephalitis and keratitis. In this study, we aimed to isolate and identify Acanthamoeba from air conditioning systems using in vitro cell culture and polymerase chain reaction assays. We also estimated the pathogenicity of the isolates by measuring their thermotolerance and studying mice models inoculated with these isolates. Of the 80 dust samples acquired, 41 (51.25%) were found to be positive for Acanthamoeba spp. using in vitro cell culture and the results were validated using PCR. Out of these 41 samples, 27 (65.9%) were thermotolerant and 16 (39%) samples could infect mice and cause histopathological effects. Highly pathogenic Acanthamoeba isolates were characterized by their thermotolerance and the ability to disseminate in all organs after infection, causing early death of infected animals. Our study thus validated the presence of pathogenic isolates of Acanthamoeba in air conditioners that may be potentially infectious to humans.
Topics: Acanthamoeba; Air Conditioning; Amebiasis; Animals; Disease Models, Animal; Dust; Egypt; Equipment Contamination; Humans; Mice; Polymerase Chain Reaction; RNA, Ribosomal, 18S
PubMed: 32999181
DOI: 10.7883/yoken.JJID.2020.049