Pathogenic Amoebae Research Articles

Differentiation of pathogenic amoebae: encystation and excystation ofAcanthamoeba culbertsoni — A model

Differentiation into dormant cysts and vegetative trophozoites is an inherent character intimately associated with the life cycle and infectivity of pathogenic amoebae. In the case of human intestinal amoebiasis encystation and excystation are of immediate relevance to the process of transmission of the disease from healthy carriers to susceptible individuals. Using a pathogenic free living amoebaAcanthamoeba culbertsoni as a model, considerable progress has been achieved in understanding the mechanism and control of the process of differentiation. The turnover of the regulatory molecule cyclic 3: ’5′ adenosine monophosphate is responsible for triggering the process of encystation. Amoebae bind effector molecules such as biogenic amines to a membrane localized receptor which itself resembles the β-adrenergic receptor of mammalian organisms. The activation of adenylate cyclase or inhibition of cyclic AMP phosphodiesterase maintain the dynamic intracellular cyclic AMP. The cytosol fraction of amoebae has a cyclic AMP binding protein. During encystation, enzymes needed for synthesis of cellulose and glycoproteins are induced. Control is exercised at transcriptional level and the process is subject to catabolic repression.

A survey of pathogenic and free-living amoebae inhabiting swimming pool water in Mexico City

A survey of pathogenic and free-living amoebae in swimming pool waters of Mexico City was performed. Among the organisms isolated those which have public health importance were Naegleria fowleri Carter and Acanthamoeba castellanii Douglas. Amoebae of the genera Acanthamoeba, Naegleria, and Vahlkampfia were recovered in their cystic stage while those specimens of the genera Amoeba, Entamoeba, Thecamoeba, and Vanella were recovered only in their trophic stage during this study. Amoebae were concentrated through filtration procedures and subsequently cultured in different culture media. Nonpathogenic amoebae also isolated by culture included: Amoeba proteus (Pallas) Leidy, Amoeba striata Penard, Paratetramitus jugosus Page, Acanthamoeba astronyxis Ray and Hayes, Vahlkampfia avara Page, Vahlkampfia inornata Page, Thecamoeba verrucosa Ehrenberg, and Vanella mira Schaeffer. Trophozoites of Entamoeba gingivalis Gros, were also recovered, both directly and by culture. Most commonly found were amoebae of the species Naegleria gruberi Schardinger (59.02%), N. fowleri (16.77%), and A. castellanii (7.64%). Least frequently found amoebae belonged to the species Thecamoeba verrucosa (0.12%). All isolated strains of N. fowleri and A. castellanii were thermophilic at 45 and 40°C, respectively, and also pathogenic when inoculated into white mice. More populated by amoebae were those swimming pools of the indoor type with an inner side garden. It was also shown that the free residual chloride values of 0.50 to 1.5 mg/liter, ordinarily used in pool waters, are not adequate for elimination of amoebae.

Frequency of Entamoeba gingivalis in human gingival scrapings.

A survey was made of gingival scrapings stained by the Papanicolaou method to assess the occurrence of Entamoeba gingivalis, a nonpathogenic-oral amoeba. Positive findings were recorded in 59% of 113 dental patients, and 32% of 96 healthy controls. These figures showed no significant changes during the last 20 years when compared with data published in 1960 and 1963. The existence of E. gingivalis and its rare appearance in the sputum should be known to cytologists because of the morphologic resemblance to Entamoeba histolytica, a pathogenic amoeba. Morphologic features are described to differentiate E. gingivalis from similar structures found in sputum.

Species specificity of immunity to malignant transformed cultured insect cells

The specificity of malignantly transformed cultured cells of the German cockroach was assayed by injecting the cells into eight additional species of cockroaches in three families. All species but the most advanced one were susceptible. The range of lethal times for the different species reflected their relationship to the species from which the cells originated. The abilities of the injected hosts to encapsulate implants of embryo fragments of the German cockroach and microcarrier beads paralleled their resistance against the malignant cells. The order of susceptibility of the cockroach species to a pathogenic amoeba paralleled their susceptibility to the malignant cells, but death from the amoeba occurred in a much shorter time. Hematocrit values were higher in the more resistant species.

Phospholipid composition and turnover of pathogenic amebas

1. 1. Evidence is presented for identifying and estimating the sphingophospholipids that predominate in Pathogenic amebas (ceramide ethanolaminephosphate, ceramide aminoethylphosphonate and sphingomyelin). 2. 2. The absence of these compounds in free living ameba suggest their use as a taxonomic criterium for identifying Entamoeba. 3. 3. All the phospholipids can be synthesized by the amebas and there is an important turnover of ceramide ethanolaminephosphate and phosphatidylethanolamine which ceases during encystment. This is the first report on the turnover of ceramides. 4. 4. Phospholipase C hydrolyzed only ceramide ethanolaminephosphate in Ameba trophozoites which are resistant to phospholipase A, suggesting ceramides are located at the outer plasma membrane.

Surface Coagglutination with Formalinized, Stained Protein a Staphylococci in the Immunologic Study of Three Pathogenic Amebae

The indirect immunofluorescence and, to a lesser extent, the immunoperoxidase methods have become the principal means of conducting immunological studies upon amebae. These procedures require the conjugation of fluorescein or enzyme with antiglobulin reagents and fixation of the amebae. The present report describes a somewhat similar methodology wherein formalinized, stained protein A staphylococci combined with specific antibody have been found to coagglutinate upon a portion of the amebic surface of living trophozoites in a fashion similar to direct immunofluorescence. The prepared staphylococci without attached antibody have also been found to coagglutinate in an identical fashion after the specific antibody has been deposited upon the amebic surface. This is comparable to indirect immunofluorescence reaction. A comparison of this procedure with the immunofluorescence method of identification and with measurement of titer of serum antibody is presented, which indicates that the new technique compares favorably with the immunofluorescence results.

Cultivation of Pathogenic and Nonpathogenic Free-Living Amebae

Cultivation of Pathogenic and Nonpathogenic Free-Living Amebae

Electrophoretic isoenzyme patterns of the pathogenic and non-pathogenic intestinal amoebae of man

Cultured stocks of Entamoeba hartmanni, Endolimax nana, Iodamoeba buetschlii and Dientamoeba fragilis were compared with the four Entamoeba histolytica groups already described ( Sargeaunt et al., 1978), by the electrophoretic patterns of three enzymes: glucose phosphate isomerase (GPI), phosphoglucomutase (PGM) and L-malate: NADP+ oxidoreductase (oxalacetate-decarboxylating) (ME). All the species were easily distinguished by their characteristic patterns.

Virulence of Pathogenic Free-Living Amebae

Virulence of Pathogenic Free-Living Amebae

Primary amoebic meningoencephalitis

As a serendipitous by-product of polio virus research, a highly fatal amoebic meningoencephalitis was recognized in animals. The causative microorganisms, contaminants of the viral cultures, were identified as small soil amoebae. These organisms, previously considered non-pathogenic, are prevalent throughout the world. Based on animal studies, the original investigators suggested the possibility of a similar disease in humans. Seven years later, human cases of amoebic meningoencephalitis were reported from widely separated areas of the world. Since 1965, a total of 79 cases have been reported. The literature of primary amoebic meningoencephalitis is presented. The history of the discovery and elucidation of this disease is reviewed. The 79 cases reported in the world literature are divided into two groups, those diagnosed retrospectively after reviewing previous deaths from meningoencephalitis, and those diagnosed at the time of the illness. The classification, morphology, pathogenicity, virulence and distribution of pathogenic soil amoebae are reviewed. The presenting clinical findings, diagnostic procedures, pathology, and management of this recently recognized, highly fatal, human disease is presented along with a report of a new case. Otolaryngologists should become familiar with this serious disorder with a transnasal portal of entry.

Pathogenic Amoebas from Brackish and Ocean Sediments, with a Description of Acanthamoeba hatchetti , n. sp.

Acanthamoeba culbertsoni was isolated from a sewage-spoil dump site near Ambrose Light, New York Bight. A second species, Acanthamoeba hatchetti, n. sp., was isolated from Brewerton Channel, Baltimore Harbor, Maryland. Both species killed laboratory mice after infection by the intranasal route.

The nature of a cytopathogenic material present in amebae of the genus Naegleria.

The Naegleria ameba cytopathogenic material (NACM) obtained from free-living and/or pathogenic amebae has been partially isolated and characterized. The evidence indicates that the material is a protein or has a protein component, and is in the estimated molecular weight range of 50,000 daltons. The partially isolated NACM, like its counterpart in the amebic lysates, is capable of sustaining itself in tissue cultures at a temperature which otherwise would inactivate it, and in serial passages through multiple dilutions. No distinctions between the NACMs from amebae of different Naegleria species or strains have been found in the biological response to the various treatments studied.

Pathogenic and Non-Pathogenic Amoebae. B. N. Singh

<i>Pathogenic and Non-Pathogenic Amoebae</i>. B. N. Singh

The Value of Electron Microscopy in the Differential Diagnosis of Amebic Meningoencephalitides.

Ultrastructural study of trophozoites and cysts in amebic encephalitides (1-4) have provided significant information pertaining to pathogenesis as well as clarification of taxonomic criteria (e.g. species, genera, etc). The use of tissues previously fixed in formalin and embedded in paraffin, then reprocessed and embedded in plastic for electron microscopic studies is useful in the evaluation of morphological features of trophozoites and cysts of these pathogenic free-living amebas. Even though the tissues disclose some post-morten autolytic alterations and distortions, trophozoite and cyst preservation is satisfactory for identification, giving excellent morphological information. Details of the overall form, which may have a role in pathogenicity, including cytoplasmic processes and projections, organelles and cyst walls, may be revealed.

Taxonomy and medical aspects of amoebae

Pathogenic and Non-Pathogenic Amoebae. By B. N. Singh. Pp. ix+235. (Macmillan: London and Basingstoke, October 1975.) £15.

Book Reviews

Journal Article Book Reviews Get access B.N. SINGH. Pathogenic and Non-Pathogenic Amoebae. New York, John Wiley & Sons, 1975. ix, 235 pp., illus. $12.50. FRANKLIN WALLACE FRANKLIN WALLACE Professor of Zoology, Department of Zoology, University of Minnesota, MinneapolisMinnesota 55455. Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of the History of Medicine and Allied Sciences, Volume XXXI, Issue 3, July 1976, Page 386, https://doi.org/10.1093/jhmas/XXXI.3.386 Published: 01 July 1976

Pathogenic and Non-Pathogenic Amoebae

Pathogenic and Non-Pathogenic Amoebae

Experimental Infections with Pathogenic Free-Living Amebae in Laboratory Primate Hosts: I. (B) a Study on Susceptibility to Acanthamoeba culbertsoni

Susceptibility to A. culbertsoni was studied in 15 Old World monkeys by intranasal, intravenous, or intrathecal inoculation of trophozoites. No clinically detectable disease resulted from either intranasal or intravenous inoculation, but 4 of 7 monkeys inoculated intrathecally succumbed to acutely fatal meningoencephalitis. Virulence of the ameba varied with cultural age of the inoculum. Size of inoculum, passages through animal tissues, and host-immune competence were other factors of consideration in pathogenicity of the ameba.

Comparative Studies on Related Free‐Living and Pathogenic Amebae With Special Reference to Acanthamoeba*

Comparative studies were conducted on the structure, nutrition, protein composition, immunology, and effect on cell cultures of Acanthamoeba sp. (Lilly A-1 strain), A. castellanii (Singh and Neff strains), A. astronyxis, A. comandoni, A. polyphaga, A. terricola, Hartmannella vermiformis, and Naegleria gruberi. Lilly A-1 strain of Acanthamoeba received special attention owing to its pathogenicity for experimental animals. Distinct differences were noted in structure, nutrition, and antigenic composition of Acanthamoeba spp. and Hartmannella, and it was concluded that their recognition as separate genera is justified. With the exception of A. terricola, all species of Acanthamoeba could be differentiated by cyst structure. Cysts of A. terricola closely resembled those of A. castellanii Singh strain, and close antigenic relationships between these 2 species were demonstrated by gel diffusion and immunoelectrophoresis (IEP); it was concluded that the 2 amebae belong in the same species. The pathogenic Acanthamoeba sp, Lilly strain differed from the nonpathogenic A. castellanii Singh strain (a) cyst structure; (b) protein distribution patterns (on disc electrophoresis);(c)soluble and particulate antigens (on gel diffusion, IEP, complement fixation, and immobilization tests); (d) capacity to induce cell-free plaques and other cytopathic effect (CPE) in mammalian monlayer cell cultures; (e) elimination of a phospholipase, responsible for some of the CPE, into the culture medium. Acanthamoeba sp. Lilly strain, which liberated more phospholipase, produced more CPE. Acanthamoeba sp. Lilly strain differed also from other species of this genus in cyst structure and antigenic composition. It was concluded, therefore, that, following the recommendation of Singh & Das, it ought to be placed in a separate species, Acanthamoeba culbertsoni.

Temperature tolerance of pathogenic and nonpathogenic free-living amoebas.

Within tested strains of the genera Naegleria and Acanthamoeba the ability to grow at high temperatures seems directly related to virulence, with nonvirulent strains unable to grow at normal or elevated body temperatures. Outside these genera, nonvirulent Hartmannella and Tetramitus do grow at elevated temperatures, which suggests a barrier to pathogenicity other than temperature sensitivity. The high optimal temperature of pathogenic Naegleria apparently explains previous difficulty in obtaining isolates from the aquatic environment.