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OUP accepted manuscript. Trans R Soc Trop Med Hyg 2022; 116:845-852. [DOI: 10.1093/trstmh/trac026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 10/28/2021] [Accepted: 03/18/2022] [Indexed: 11/13/2022] Open
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Kalra SK, Sharma P, Shyam K, Tejan N, Ghoshal U. Acanthamoeba and its pathogenic role in granulomatous amebic encephalitis. Exp Parasitol 2019; 208:107788. [PMID: 31647916 DOI: 10.1016/j.exppara.2019.107788] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 10/11/2019] [Accepted: 10/19/2019] [Indexed: 01/13/2023]
Abstract
Acanthamoeba is a free-living amoeba that is widely distributed in the environment. It is an opportunist protist, which is known to cause rare yet fatal infection of the central nervous system (CNS), granulomatous amebic encephalitis (GAE) in humans. GAE cases are increasingly been reported among immunocompromised patients, with few cases in immunocompetent hosts. Diagnosis of GAE primarily includes neuroimaging, microscopy, cerebrospinal fluid (CSF) culture, histopathology, serology and molecular techniques. Early diagnosis is vital for proper management of infected patients. Combination therapeutic approach has been tried in various GAE cases reported worldwide. We tried to present a comprehensive review, which summarizes on the epidemiology of GAE caused by Acanthamoeba along with the associated clinical symptoms, risk factors, diagnosis and treatment of GAE among infected patients.
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Affiliation(s)
- Sonali K Kalra
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Bajhol, Distt. Solan, 173229, HP, India.
| | - Palvi Sharma
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Bajhol, Distt. Solan, 173229, HP, India
| | - Kirti Shyam
- Faculty of Applied Sciences and Biotechnology, Shoolini University of Biotechnology and Management Sciences, Bajhol, Distt. Solan, 173229, HP, India
| | - Nidhi Tejan
- Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Raebareili Road, Lucknow, 226014, UP, India
| | - Ujjala Ghoshal
- Department of Microbiology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Raebareili Road, Lucknow, 226014, UP, India
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Omaña-Molina M, Sanchez-Rocha R, Hernandez-Martinez D, Romero Grijalva M, Salinas-Lara C, Rodriguez-Sosa M, Juarez-Avelar I, Salazar-Villatoro L, Gonzalez-Robles A, Mendez-Cruz AR, Aley-Medina P, Espinosa-Villanueva J, Castelan-Ramirez I, Lorenzo-Morales J. Type 2 diabetes mellitus BALB/c mice are more susceptible to granulomatous amoebic encephalitis: Immunohistochemical study. Exp Parasitol 2017; 183:150-159. [PMID: 28917708 DOI: 10.1016/j.exppara.2017.09.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/06/2017] [Accepted: 09/11/2017] [Indexed: 11/28/2022]
Abstract
Granulomatous amoebic encephalitis (GAE) is a chronic, difficult to resolve infection caused by amphizoic amoebae of the genus Acanthamoeba, which in most cases occurs in immunosuppressed persons or with chronic diseases such as diabetes. In this study, we describe the early events of A. culbertsoni infection of GAE in diabetic mice model. Diabetes was induced in male BALB/c mice, with a dose of streptozotocin (130 mg/kg). Healthy and diabetic mice were inoculated via intranasal with 1 × 106 trophozoites of A. culbertsoni. Then were sacrificed and fixed by perfusion at 24, 48, 72 and 96 h post-inoculation, the brains and nasopharyngeal meatus were processed to immunohistochemical analysis. Invasion of trophozoites in diabetic mice was significantly greater with respect to inoculated healthy mice. Trophozoites and scarce cysts were immunolocalized in respiratory epithelial adjacent bone tissue, olfactory nerve packets, Schwann cells and the epineurium base since early 24 h post-inoculation. After 48 h, trophozoites were observed in the respiratory epithelium, white matter of the brain, subcortical central cortex and nasopharyngeal associated lymphoid tissue (NALT). At 72 h, cysts and trophozoites were immunolocalized in the olfactory bulb with the presence of a low inflammatory infiltrate characterized by polymorphonuclear cells. Scarce amoebae were observed in the granular layer of the cerebellum without evidence of inflammation or tissue damage. No amoebas were observed at 96 h after inoculation, suggesting penetration to other tissues at this time. In line with this, no inflammatory infiltrate was observed in the surrounding tissues where the amoebae were immunolocalized, which could contribute to the rapid spread of infection, particularly in diabetic mice. All data suggest that trophozoites invade the tissues by separating the superficial cells, penetrating between the junctions without causing cytolytic effect in the adjacent cells and subsequently reaching the CNS, importantly, diabetes increases the susceptibility to amoebae infection, which could favor the GAE development.
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Affiliation(s)
- Maritza Omaña-Molina
- Laboratory of Amphizoic Amoebae, Faculty of Superior Studies, Medicine, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico.
| | - Raquel Sanchez-Rocha
- Laboratory of Amphizoic Amoebae, Faculty of Superior Studies, Medicine, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Dolores Hernandez-Martinez
- Laboratory of Amphizoic Amoebae, Faculty of Superior Studies, Medicine, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Miriam Romero Grijalva
- Laboratory of Amphizoic Amoebae, Faculty of Superior Studies, Medicine, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Citlaltepetl Salinas-Lara
- Laboratory of Histology and Pathology, Faculty of Superior Studies, Medicine, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Miriam Rodriguez-Sosa
- Laboratory of Innate Immunity, UBIMED, Faculty of Superior Studies, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Imelda Juarez-Avelar
- Laboratory of Innate Immunity, UBIMED, Faculty of Superior Studies, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Lizbeth Salazar-Villatoro
- Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies, Mexico City, Mexico
| | - Arturo Gonzalez-Robles
- Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies, Mexico City, Mexico
| | - Adolfo Rene Mendez-Cruz
- Laboratory of Amphizoic Amoebae, Faculty of Superior Studies, Medicine, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Patricia Aley-Medina
- Neuromorphology Laboratory, Faculty of Superior Studies, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Jesus Espinosa-Villanueva
- Neuromorphology Laboratory, Faculty of Superior Studies, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Ismael Castelan-Ramirez
- Laboratory of Amphizoic Amoebae, Faculty of Superior Studies, Medicine, UNAM, Iztacala, Tlalnepantla, State of Mexico, Mexico
| | - Jacob Lorenzo-Morales
- University Institute of Tropical Diseases and Public Health of the Canary Islands, University of La Laguna, La Laguna, Tenerife, Canary Islands, Spain
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Behera HS, Satpathy G, Tripathi M. Isolation and genotyping of Acanthamoeba spp. from Acanthamoeba meningitis/ meningoencephalitis (AME) patients in India. Parasit Vectors 2016; 9:442. [PMID: 27507421 PMCID: PMC4977702 DOI: 10.1186/s13071-016-1729-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 07/26/2016] [Indexed: 11/17/2022] Open
Abstract
Background Acanthamoeba spp. are free-living ubiquitous protozoans capable of causing Acanthamoeba meningitis/meningoencephalitis (AME) of the central nervous system in humans. Acanthamoeba spp. are divided into 20 different genotypes (T1–T20) on the basis of variation in nucleotide sequences of the 18S rRNA gene. The objective of this study was to identify the genotypes of Acanthamoeba spp. in patients of Acanthamoeba meningitis/meningoencephalitis (AME) using 18S rRNA gene-based PCR assay. The present study provides information regarding the involvement of the most prevalent and predominant genotype of Acanthamoeba spp. in Acanthamoeba meningitis/meningoencephalitis infections in India. Methods Cerebrospinal fluid (CSF) was collected from 149 clinically suspected Acanthamoeba meningitis/meningoencephalitis (AME) patients reporting to the outpatient department/causality services of the Neurosciences Centre, AIIMS, New Delhi, India during the past five years. Samples were inoculated onto 2 % non-nutrient agar plates overlaid with E. coli and incubated at 30 °C for 14 days. Among 149 suspected patients, ten were found culture-positive for Acanthamoeba spp. out of which six isolates were established in axenic culture for molecular analysis. DNA was isolated and a PCR assay was performed for amplification of the Diagnostic fragment 3 (DF3) (~280 bp) region of the 18S rRNA gene from axenic culture of six Acanthamoeba spp. isolates. Rns genotyping was performed on the basis of the variation in nucleotide sequences of DF3 region of the 18S rRNA gene. Results In the phylogenetic analysis, all of the six Acanthamoeba spp. isolates were found to belong to genotype T4. The sequence homology search for these six isolates in the NCBI databank showed homology with the available strains of Acanthamoeba spp. The newly generated sequences are available in the GenBank database under accession numbers KT004416–KT004421. Conclusions In the present study, genotype T4 was found as the most prevalent and predominant genotype in Acanthamoeba meningitis/ meningoencephalitis infections. Hence further studies are needed to develop optimal therapeutic strategy against Acanthamoeba spp. of genotype T4 to combat against the infections.
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Affiliation(s)
- Himanshu Sekhar Behera
- Ocular Microbiology, Dr. R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, 110029, India
| | - Gita Satpathy
- Ocular Microbiology, Dr. R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, 110029, India.
| | - Manjari Tripathi
- Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, 110029, India
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Abstract
Pathogenic FLA are ubiquitous protozoans and despite frequent human contact remain a rare cause of often devastating infection with poor prognosis. Given changes in climate, human encroachment into the environment, increasing immunosuppression, and improving diagnostic capacity, it is likely we will see increased cases in the future. Early diagnosis is challenging but crucial to achieving a favourable outcome. It is best facilitated by improved awareness of FLA disease, appropriate clinical suspicion and early diagnostic testing.
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Acanthamoeba encephalitis: isolation of genotype T1 in mycobacterial liquid culture medium. J Clin Microbiol 2014; 53:735-9. [PMID: 25502534 DOI: 10.1128/jcm.02887-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
We report a case of Acanthamoeba encephalitis diagnosed from an antemortem brain biopsy specimen, where the organism was first isolated in mycobacterial liquid medium and first identified by using a sequence generated by a commercial panfungal sequencing assay. We correlate susceptibility results with clinical outcome.
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Amissah NA, Gryseels S, Tobias NJ, Ravadgar B, Suzuki M, Vandelannoote K, Durnez L, Leirs H, Stinear TP, Portaels F, Ablordey A, Eddyani M. Investigating the role of free-living amoebae as a reservoir for Mycobacterium ulcerans. PLoS Negl Trop Dis 2014; 8:e3148. [PMID: 25188535 PMCID: PMC4154674 DOI: 10.1371/journal.pntd.0003148] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 07/25/2014] [Indexed: 11/20/2022] Open
Abstract
Background The reservoir and mode of transmission of Mycobacterium ulcerans, the causative agent of Buruli ulcer, still remain a mystery. It has been suggested that M. ulcerans persists with difficulty as a free-living organism due to its natural fragility and inability to withstand exposure to direct sunlight, and thus probably persists within a protective host environment. Methodology/Principal Findings We investigated the role of free-living amoebae as a reservoir of M. ulcerans by screening the bacterium in free-living amoebae (FLA) cultures isolated from environmental specimens using real-time PCR. We also followed the survival of M. ulcerans expressing green fluorescence protein (GFP) in Acanthameoba castellanii by flow cytometry and observed the infected cells using confocal and transmission electron microscopy for four weeks in vitro. IS2404 was detected by quantitative PCR in 4.64% of FLA cultures isolated from water, biofilms, detritus and aerosols. While we could not isolate M. ulcerans, 23 other species of mycobacteria were cultivated from inside FLA and/or other phagocytic microorganisms. Laboratory experiments with GFP-expressing M. ulcerans in A. castellani trophozoites for 28 days indicated the bacteria did not replicate inside amoebae, but they could remain viable at low levels in cysts. Transmission electron microscopy of infected A. castellani confirmed the presence of bacteria within both trophozoite vacuoles and cysts. There was no correlation of BU notification rate with detection of the IS2404 in FLA (r = 0.07, n = 539, p = 0.127). Conclusion/Significance This study shows that FLA in the environment are positive for the M. ulcerans insertion sequence IS2404. However, the detection frequency and signal strength of IS2404 positive amoabae was low and no link with the occurrence of BU was observed. We conclude that FLA may host M. ulcerans at low levels in the environment without being directly involved in the transmission to humans. Mycobacterium ulcerans, the causative agent of Buruli ulcer (BU) is an environmental pathogen known to reside in aquatic habitat. However, the reservoir and modes of transmission to humans still remain unknown. M. ulcerans can probably not live freely due to its natural fragility and inability to withstand exposure to direct sunlight. This study investigated the hypothesis that free-living amoebae (FLA) can serve as a reservoir of M. ulcerans by testing for its presence in amoebae isolated from water bodies in BU endemic and non-endemic communities and whether the pathogen can remain viable when experimentally infected in amoebae in the laboratory. We detected only one (IS2404) of the three (IS2606 and KRB) targets for the presence of M. ulcerans in amoebae cultures and found no correlation between its presence in the environment and BU notification rate. M. ulcerans remained viable at low levels in amoebae for 28 days in vitro. We therefore conclude that FLA may host M. ulcerans at low levels in the environment without being directly involved in the transmission to humans.
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Affiliation(s)
- Nana Ama Amissah
- Bacteriology Department, Noguchi Memorial Institute for Medical Research, Accra, Ghana
- * E-mail:
| | - Sophie Gryseels
- Evolutionary Ecology Group, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Nicholas J. Tobias
- Department of Microbiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Bahram Ravadgar
- Department of Microbiology, Monash University, Victoria, Australia
| | - Mitsuko Suzuki
- Parasitology Department, Noguchi Memorial Institute for Medical Research, Accra, Ghana
| | - Koen Vandelannoote
- Evolutionary Ecology Group, Department of Biology, University of Antwerp, Antwerp, Belgium
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Lies Durnez
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Herwig Leirs
- Evolutionary Ecology Group, Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Timothy P. Stinear
- Department of Microbiology, University of Melbourne, Melbourne, Victoria, Australia
- Department of Microbiology, Monash University, Victoria, Australia
| | - Françoise Portaels
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
| | - Anthony Ablordey
- Bacteriology Department, Noguchi Memorial Institute for Medical Research, Accra, Ghana
| | - Miriam Eddyani
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
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Abstract
Rhizobiales (formerly named Rickettsiales) cause in rare instances meningitis and meningovasculitis, respectively. In case of history of exposure, infection by Rhizobiales needs to be considered since both diagnosis and therapy may be extremely difficult and pathogen-specific. The same applies to protozoa; in this chapter, Babesia species, free-living amoebae and Entamoeba histolytica infection, including severe meningitis and brain abscess, infection by Trypanosoma species (South American and African trypanosomiasis) are discussed with respect to history, epidemiology, clinical signs, and symptoms as well as differential diagnosis and therapy. Parasitic flatworms and roundworms, potentially able to invade the central nervous system, trematodes (flukes), cestodes (in particular, Cysticercus cellulosae), but also nematodes (in particular, Strongyloides spp. in the immunocompromised) are of worldwide importance. In contrast, filarial worms, Toxocara spp., Trichinella spp., Gnathostoma and Angiostrongylus spp. are seen only in certain geographically confined areas. Even more regionally confined are infestations of the central nervous system by metazoa, in particular, tongue worms (=arthropods) or larvae of flies (=maggots). The aim of this chapter is (1) to alert the neurologist to these infections, and (2) to enable the attending emergency neurologist to take a knowledgeable history, with an emphasis on epidemiology, clinical signs, and symptoms as well as therapeutic management possibilities.
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Affiliation(s)
- Erich Schmutzhard
- Department of Neurology, Medical University Hospital Innsbruck, Innsbruck, Austria.
| | - Raimund Helbok
- Department of Neurology, Medical University Hospital Innsbruck, Innsbruck, Austria
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Badenoch PR, Grimmond TR, Cadwgan J, Deayton SE, Essery MSL, Hill ABD. Nasal Carriage of Free-Living Amoebae. MICROBIAL ECOLOGY IN HEALTH AND DISEASE 2009. [DOI: 10.3109/08910608809141538] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- P. R. Badenoch
- Department of Ophthalmology, Flinders Medical Centre, School of Biological Sciences, Bedford Park, 5042, South Australia
| | - T. R. Grimmond
- Clinical Microbiology Flinders Medical Centre, School of Biological Sciences, Bedford Park, 5042, South Australia
| | - J. Cadwgan
- Flinders University, Bedford Park, 5042, South Australia
| | - S. E. Deayton
- Flinders University, Bedford Park, 5042, South Australia
| | | | - And B. D. Hill
- Flinders University, Bedford Park, 5042, South Australia
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Abstract
Acanthamoeba spp. are free-living amebae that inhabit a variety of air, soil, and water environments. However, these amebae can also act as opportunistic as well as nonopportunistic pathogens. They are the causative agents of granulomatous amebic encephalitis and amebic keratitis and have been associated with cutaneous lesions and sinusitis. Immuno compromised individuals, including AIDS patients, are particularly susceptible to infections with Acanthamoeba. The immune defense mechanisms that operate against Acanthamoeba have not been well characterized, but it has been proposed that both innate and acquired immunity play a role. The ameba's life cycle includes an active feeding trophozoite stage and a dormant cyst stage. Trophozoites feed on bacteria, yeast, and algae. However, both trophozoites and cysts can retain viable bacteria and may serve as reservoirs for bacteria with human pathogenic potential. Diagnosis of infection includes direct microscopy of wet mounts of cerebrospinal fluid or stained smears of cerebrospinal fluid sediment, light or electron microscopy of tissues, in vitro cultivation of Acanthamoeba, and histological assessment of frozen or paraffin-embedded sections of brain or cutaneous lesion biopsy material. Immunocytochemistry, chemifluorescent dye staining, PCR, and analysis of DNA sequence variation also have been employed for laboratory diagnosis. Treatment of Acanthamoeba infections has met with mixed results. However, chlorhexidine gluconate, alone or in combination with propamidene isethionate, is effective in some patients. Furthermore, effective treatment is complicated since patients may present with underlying disease and Acanthamoeba infection may not be recognized. 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.
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Affiliation(s)
- Francine Marciano-Cabral
- Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia 23298-0678, USA.
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Abstract
The unique structure of the human eye as well as exposure of the eye directly to the environment renders it vulnerable to a number of uncommon infectious diseases caused by fungi and parasites. Host defenses directed against these microorganisms, once anatomical barriers are breached, are often insufficient to prevent loss of vision. Therefore, the timely identification and treatment of the involved microorganisms are paramount. The anatomy of the eye and its surrounding structures is presented with an emphasis upon the association of the anatomy with specific infection of fungi and parasites. For example, filamentous fungal infections of the eye are usually due to penetrating trauma by objects contaminated by vegetable matter of the cornea or globe or, by extension, of infection from adjacent paranasal sinuses. Fungal endophthalmitis and chorioretinitis, on the other hand, are usually the result of antecedent fungemia seeding the ocular tissue. Candida spp. are the most common cause of endogenous endophthalmitis, although initial infection with the dimorphic fungi may lead to infection and scarring of the chorioretina. Contact lens wear is associated with keratitis caused by yeasts, filamentous fungi, and Acanthamoebae spp. Most parasitic infections of the eye, however, arise following bloodborne carriage of the microorganism to the eye or adjacent structures.
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Klotz SA, Penn CC, Negvesky GJ, Butrus SI. Fungal and parasitic infections of the eye. Clin Microbiol Rev 2000; 13:662-85. [PMID: 11023963 PMCID: PMC88956 DOI: 10.1128/cmr.13.4.662] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The unique structure of the human eye as well as exposure of the eye directly to the environment renders it vulnerable to a number of uncommon infectious diseases caused by fungi and parasites. Host defenses directed against these microorganisms, once anatomical barriers are breached, are often insufficient to prevent loss of vision. Therefore, the timely identification and treatment of the involved microorganisms are paramount. The anatomy of the eye and its surrounding structures is presented with an emphasis upon the association of the anatomy with specific infection of fungi and parasites. For example, filamentous fungal infections of the eye are usually due to penetrating trauma by objects contaminated by vegetable matter of the cornea or globe or, by extension, of infection from adjacent paranasal sinuses. Fungal endophthalmitis and chorioretinitis, on the other hand, are usually the result of antecedent fungemia seeding the ocular tissue. Candida spp. are the most common cause of endogenous endophthalmitis, although initial infection with the dimorphic fungi may lead to infection and scarring of the chorioretina. Contact lens wear is associated with keratitis caused by yeasts, filamentous fungi, and Acanthamoebae spp. Most parasitic infections of the eye, however, arise following bloodborne carriage of the microorganism to the eye or adjacent structures.
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Affiliation(s)
- S A Klotz
- Section of Infectious Diseases, Veterans Affairs Medical Center, Kansas City, Missouri 64128, USA.
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Abstract
Free-living amebae belonging to the genus Acanthamoeba are the causative agents of granulomatous amebic encephalitis, a chronic progressive disease of the central nervous system, and of amebic keratitis, a chronic eye infection. Granulomatous amebic encephalitis occurs more frequently in immunocompromised patients while keratitis occurs in healthy individuals. The recent increased incidence in Acanthamoeba infections is due in part to infection in patients with acquired immune deficiency syndrome, while that for keratitis is due to the increased use of contact lenses. Understanding the mechanism of host resistance to Acanthamoeba is essential since the amebae are resistant to many therapeutic agents. Studies in our laboratory as well as from others have demonstrated that macrophages from immunocompetent animals are important effector cells against Acanthamoeba. We have demonstrated also that microglial cells, resident macrophages of the brain, elicit cytokines in response to A. castellanii. Neonatal rat cortical microglia from Sprague-Dawley rats co-cultured with A. castellanii produced mRNA for the inflammatory cytokines, interleukin 1alpha, interleukin 1beta, and tumor necrosis factor alpha. In addition, scanning and transmission electron microscopy revealed that microglia ingested and destroyed A. castellanii in vitro. These results implicate macrophages as playing an effector role against Acanthamoeba and suggest immune modulation as a potential alternative therapeutic mode of treatment for these infections.
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Affiliation(s)
- F Marciano-Cabral
- Department of Microbiology & Immunology, Medical College of Virginia of Virginia Commonwealth University, Richmond 23298-0678, USA. ))).
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Badenoch PR, Adams M, Coster DJ. Corneal virulence, cytopathic effect on human keratocytes and genetic characterization of Acanthamoeba. Int J Parasitol 1995; 25:229-39. [PMID: 7622330 DOI: 10.1016/0020-7519(94)00075-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Acanthamoeba keratitis is a sight-threatening complication of corneal trauma or contact lens wear. Although the majority of corneal isolates of Acanthamoeba belong to Group II in the Pussard-Pons classification based on cyst morphology, they have been placed in at least six species and their genetic relatedness is uncertain. The aim of this study was to determine the virulence of, and the relationship among, strains derived from the cornea, the nasal mucosa, and other environmental sources. To assess virulence, 10(4) trophozoites of each strain were incubated with monolayers of human corneal fibroblasts. By day 7, 12 of 29 strains tested had induced significant cytopathic changes. In addition, inocula of 10(4) cysts or trophozoites with 10(6) Corynebacterium xerosis were injected into the corneas of Porton rats; 11 amoebic strains induced infection within 7 days. The correlation between the virulence of trophozoites in vitro and in vivo was 86%. Using allozyme electrophoresis, 23 Acanthamoeba strains clustered into 5 major phylogenic divisions. Three divisions contained one or more strains that were virulent in the rat cornea. Virulent Pussard-Pons Group II strains clustered tightly to a fixed allelic difference of 13.6%. The eight corneal isolates clustered to 33%, dividing into three lineages. Five avirulent nasal isolates were strongly differentiated from other Group II strains. The results were not in accord with species designations based primarily on morphological criteria. These data suggest that particular subsets of Acanthamoeba strains are virulent in the human cornea.
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Affiliation(s)
- P R Badenoch
- Department of Ophthalmology, Flinders Medical Centre, Bedford Park, Australia
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15
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Martinez AJ, Visvesvara GS. Laboratory Diagnosis of Pathogenic Free-Living Amoebas: Naegleria, Acanthamoeba, and Leptomyxid. Clin Lab Med 1991. [DOI: 10.1016/s0272-2712(18)30524-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Flores BM, Garcia CA, Stamm WE, Torian BE. Differentiation of Naegleria fowleri from Acanthamoeba species by using monoclonal antibodies and flow cytometry. J Clin Microbiol 1990; 28:1999-2005. [PMID: 2229384 PMCID: PMC268093 DOI: 10.1128/jcm.28.9.1999-2005.1990] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Monoclonal antibodies to Naegleria fowleri and Acanthamoeba polyphaga were analyzed by enzyme-linked immunosorbent assay, indirect immunofluorescence microscopy, and fluorescence flow cytometry to assess specificity and cross-reactivity with axenically cultured N. fowleri and Acanthamoeba spp. Four monoclonal antibodies to N. fowleri were specific for N. fowleri and had no reactivity to A. polyphaga. Similarly, four monoclonal antibodies to A. polyphaga did not react with N. fowleri. Two of the four monoclonal antibodies to A. polyphaga did not react with other Acanthamoeba spp. tested, while two of the antibodies demonstrated a high degree of cross-reactivity with a putative Acanthamoeba castellanii strain by immunofluorescence microscopy; this was confirmed by fluorescence flow cytometry for one of the antibodies. These monoclonal antibodies were used to identify Acanthamoeba trophozoites in infected brain sections of a patient who died of suspected Acanthamoeba-caused granulomatous amoebic encephalitis, demonstrating potential utility in the direct identification of N. fowleri and Acanthamoeba spp. in clinical specimens.
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Affiliation(s)
- B M Flores
- Department of Microbiology, Immunology and Parasitology, Louisiana State University Medical Center, New Orleans 70112
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Visvesvara GS, Stehr-Green JK. Epidemiology of free-living ameba infections. THE JOURNAL OF PROTOZOOLOGY 1990; 37:25S-33S. [PMID: 2258827 DOI: 10.1111/j.1550-7408.1990.tb01142.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Small free-living amebas belonging to the genera Acanthamoeba and Naegleria occur world-wide. They have been isolated from a variety of habitats including fresh water, thermal discharges of power plants, soil, sewage and also from the nose and throats of patients with respiratory illness as well as healthy persons. Although the true incidence of human infections with these amebas is not known, it is believed that as many as 200 cases of central nervous system infections due to these amebas have occurred worldwide. A majority (144) of these cases have been due to Naegleria fowleri which causes an acute, fulminating disease, primary amebic meningoencephalitis. The remaining 56 cases have been reported as due either to Acanthamoeba or some other free-living ameba which causes a subacute and/or chronic infection called granulomatous amebic encephalitis (GAE). Acanthamoeba, in addition to causing GAE, also causes nonfatal, but nevertheless painful, vision-threatening infections of the human cornea, Acanthamoeba keratitis. Infections due to Acanthamoeba have also been reported in a variety of animals. These observations, together with the fact that Acanthamoeba spp., Naegleria fowleri, and Hartmannella sp. can harbor pathogenic microorganisms such as Legionella and or mycobacteria indicate the public health importance of these amebas.
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Affiliation(s)
- G S Visvesvara
- Division of Parasitic Diseases, Centers for Disease Control, U.S. Department of Health and Human Services, Atlanta, Georgia 30333
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