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Rayamajhee B, Willcox MDP, Henriquez FL, Petsoglou C, Subedi D, Carnt N. Acanthamoeba, an environmental phagocyte enhancing survival and transmission of human pathogens. Trends Parasitol 2022; 38:975-990. [PMID: 36109313 DOI: 10.1016/j.pt.2022.08.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/10/2022] [Accepted: 08/11/2022] [Indexed: 01/13/2023]
Abstract
The opportunistic protist Acanthamoeba, which interacts with other microbes such as bacteria, fungi, and viruses, shows significant similarity in cellular and functional aspects to human macrophages. Intracellular survival of microbes in this microbivorous amoebal host may be a crucial step for initiation of infection in higher eukaryotic cells. Therefore, Acanthamoeba-microbe adaptations are considered an evolutionary model of macrophage-pathogen interactions. This paper reviews Acanthamoeba as an emerging human pathogen and different ecological interactions between Acanthamoeba and microbes that may serve as environmental training grounds and a genetic melting pot for the evolution, persistence, and transmission of potential human pathogens.
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Affiliation(s)
- Binod Rayamajhee
- School of Optometry and Vision Science, Faculty of Medicine and Health, University of New South Wales (UNSW), Sydney, Australia.
| | - Mark D P Willcox
- School of Optometry and Vision Science, Faculty of Medicine and Health, University of New South Wales (UNSW), Sydney, Australia.
| | - Fiona L Henriquez
- Institute of Biomedical and Environmental Health Research, School of Health and Life Sciences, University of the West of Scotland, Blantyre, South Lanarkshire, G72 0LH, UK
| | - Constantinos Petsoglou
- Sydney and Sydney Eye Hospital, Southeastern Sydney Local Health District, Sydney, Australia; Save Sight Institute, University of Sydney, Sydney, Australia
| | - Dinesh Subedi
- School of Biological Sciences, Monash University, Clayton, Australia
| | - Nicole Carnt
- School of Optometry and Vision Science, Faculty of Medicine and Health, University of New South Wales (UNSW), Sydney, Australia
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2
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Nageeb MM, Eldeek HEM, Attia RAH, Sakla AA, Alkhalil SS, Farrag HMM. Isolation and morphological and molecular characterization of waterborne free-living amoebae: Evidence of potentially pathogenic Acanthamoeba and Vahlkampfiidae in Assiut, Upper Egypt. PLoS One 2022; 17:e0267591. [PMID: 35802617 PMCID: PMC9269480 DOI: 10.1371/journal.pone.0267591] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/12/2022] [Indexed: 12/15/2022] Open
Abstract
Free-living amoebae (FLA) are gaining attention due to the increasing number of related grave central nervous system (CNS) and sight-threatening eye infections and their role as Trojan horses for many bacteria and viruses. This study was conducted in Assiut City, Egypt to detect the presence of FLA in different water sources using morphological and molecular approaches and determine their potential pathogenicity. A total of 188 water samples (100 tap, 80 tank, and 8 swimming pool samples) were collected, cultivated on non-nutrient agar seeded with Escherichia coli, and inspected for FLA. Thermo- and osmo-tolerance assays were performed to determine their pathogenicity. Polymerase chain reaction and sequence analysis were performed to confirm the identification and analyze the genotype. Overall, 52 samples (27.7%) were positive for FLA. Of these, 20.7% were identified as Acanthamoeba, 1.6% as Vahlkampfiidae, and 5.3% as mixed Acanthamoeba and Vahlkampfiidae. Seven species of Acanthamoeba were recognized, of which A. triangularis, A. polyphaga, A. lenticulata, and A. culbertsoni are thermo- and osmo-tolerant, and A. astronyxis, A. comandoni, and A. echinulata are non-thermo- and non-osmo-tolerant. The phylogeny analysis revealed T4 and T7 genotypes. Among Vahlkampfiids, 61.5% were identified as thermo- and osmo-tolerant Vahlkampfia, and 30.8% were identified as non-pathogenic Naegleria. One isolate (7.7%) was identified as potentially pathogenic Allovahlkampfia, as confirmed by sequencing. This is the first report documenting the occurrence and phylogeny of waterborne FLA (Acanthamoeba/Vahlkampfiidae) in Assiut, Egypt. The presence of potentially pathogenic FLA highlights the possible health hazards and the need for preventive measures.
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Affiliation(s)
- Martina M. Nageeb
- Medical Parasitology Department, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Hanan E. M. Eldeek
- Medical Parasitology Department, Faculty of Medicine, Assiut University, Assiut, Egypt
- * E-mail: ,
| | - Rasha A. H. Attia
- Medical Parasitology Department, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Atef A. Sakla
- Medical Parasitology Department, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Samia S. Alkhalil
- Department of Clinical Laboratory Sciences, Faculty of Applied Medical Sciences, Shaqra University, Shaqra, Saudi Arabia
| | - Haiam Mohamed Mahmoud Farrag
- Medical Parasitology Department, Faculty of Medicine, Assiut University, Assiut, Egypt
- Department of Clinical Laboratory Sciences, Faculty of Applied Medical Sciences, Shaqra University, Shaqra, Saudi Arabia
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Karsenti N, Purssell A, Lau R, Ralevski F, Bhasker S, Raheel H, Boggild AK. Surveillance of Amoebic Keratitis-Causing Acanthamoebae for Potential Bacterial Endosymbionts in Ontario, Canada. Pathogens 2022; 11:pathogens11060661. [PMID: 35745515 PMCID: PMC9230791 DOI: 10.3390/pathogens11060661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/02/2022] [Accepted: 06/07/2022] [Indexed: 02/04/2023] Open
Abstract
Acanthamoeba spp. are the causative pathogens of several infections, including amoebic keratitis (AK), a vision-threatening infection. Acanthamoebae from corneal specimens of patients with AK harbor bacterial endosymbionts, which may increase virulence. We sought to understand the spectrum of bacterial endosymbionts present in clinical isolates of Acanthamoeba spp. identified in our reference parasitology laboratory. Isolates of Acanthamoeba spp. obtained from our biobank of anonymized corneal scrapings were screened for potential endosymbionts by PCR using primer pairs detecting bacteria belonging to orders Chlamydiales, Rickettsiales, or Legionellales and pan16S primers. Three primer pairs specific to the 18s rRNA gene of Acanthamoeba spp. were used for the amplification of Acanthamoeba DNA used for sequencing. Sanger sequencing of all PCR products was performed, followed by BLAST analysis for species identification. We screened 26 clinical isolates of Acanthamoeba spp. for potential endosymbionts. Five isolates (19%) were found to contain bacterial DNA belonging to Legionellales. Three (11%) contained members of the Rickettsiales and Pseudomonas genticulata was detected in a Rickettsia-positive sample. One strain (4%) contained Neochlamydia hartmannellae, a member of the Chlamydiales order. Bacterial endosymbionts are prevalent in clinical strains of Acanthamoeba causing AK isolated from corneal scrapings. The demonstration of these organisms in clinical Acanthamoeba isolates supports a potential exploration of anti-endosymbiont therapeutics as an adjuvant therapy in the treatment of AK.
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Affiliation(s)
- Nessika Karsenti
- Schulich School of Medicine & Dentistry, London, ON N6A 5C1, Canada; (N.K.); (H.R.)
| | - Andrew Purssell
- Faculty of Medicine, University of Ottawa, Ottawa, ON K1N 6N5, Canada;
| | - Rachel Lau
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON M5G 1M1, Canada; (R.L.); (F.R.)
| | - Filip Ralevski
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON M5G 1M1, Canada; (R.L.); (F.R.)
| | - Shveta Bhasker
- Institute of Health Policy, Management and Evaluation, Dalla Lana School of Public Health, University of Toronto, Toronto, ON M5S 1A1, Canada;
| | - Hira Raheel
- Schulich School of Medicine & Dentistry, London, ON N6A 5C1, Canada; (N.K.); (H.R.)
| | - Andrea K. Boggild
- Tropical Disease Unit, Division of Infectious Diseases, UHN-Toronto General Hospital, Toronto, ON M5G 2C4, Canada
- Department of Medicine, University of Toronto, Toronto, ON M5S 1A1, Canada
- Institute of Medical Science, University of Toronto, Toronto, ON M5S 1A1, Canada
- Correspondence: ; Tel.: +1-416-340-3675
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Ward MS, Hastings JP, Shmunes KM, Ronquillo Y, Hoopes PC, Moshirfar M. Atypical presentation of acanthamoeba keratitis resembling central toxic keratopathy. Am J Ophthalmol Case Rep 2022; 25:101243. [PMID: 35028488 PMCID: PMC8715135 DOI: 10.1016/j.ajoc.2021.101243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 08/25/2021] [Accepted: 12/13/2021] [Indexed: 11/06/2022] Open
Abstract
PURPOSE To describe an atypical case of acanthamoeba keratitis with positive in vivo confocal microscopy in a non-contact lens user who presented with signs and symptoms suggestive of central toxic keratopathy. OBSERVATIONS The patient presented with bilateral, though sequential, decreased visual acuity with mild pain. Examination showed stromal haze with corneal flattening and thinning without epithelial defects. Optical coherence tonometry of the right eye revealed an inverse dome-shaped appearance of the opacity and in-vivo confocal imaging showed double-walled cysts consistent with acanthamoeba. Corneal haze, stromal loss, resolved and visual acuity improved over time. CONCLUSION AND IMPORTANCE Acanthamoeba is a rare cause of infectious keratitis that is most often associated with contact lens wear in developed countries. Typically, it presents with a unilateral decrease in visual acuity, photophobia, watering, and pain that is out of proportion to slit lamp examination findings. However, many atypical presentations have been reported in the literature. Consequently, it may be misdiagnosed, especially early in the course of the disease. This delay in diagnosis can lead to progressive ulceration and visual impairment. In addition, cyst formation can make eradication with anti-amoebic treatment especially difficult.Central toxic keratopathy is a non-inflammatory clinical syndrome of unknown etiology that is most often associated with excimer laser ablation, though other associated causes have been reported. It is characterized by a central or paracentral opacity with corneal stromal loss and resultant hyperopic shift. The opacification and stromal loss mostly resolve over the course of months with an improvement in visual acuity. This report may help physicians broaden their differential and correctly diagnose atypical presentations of amoebic infection.
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Affiliation(s)
| | - Jordan P. Hastings
- California Northstate University College of Medicine, Elk Grove, CA, USA
| | | | | | | | - Majid Moshirfar
- Hoopes Vision Research Center, Draper, UT, USA
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
- Utah Lions Eye Bank, Murray, UT, USA
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Efficient nested-PCR-based method development for detection and genotype identification of Acanthamoeba from a small volume of aquatic environmental sample. Sci Rep 2021; 11:21740. [PMID: 34741041 PMCID: PMC8571327 DOI: 10.1038/s41598-021-00968-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2019] [Accepted: 10/15/2021] [Indexed: 12/17/2022] Open
Abstract
Acanthamoeba spp. are opportunistic human pathogens that cause granulomatous amoebic encephalitis and keratitis, and their accurate detection and enumeration in environmental samples is a challenge. In addition, information regarding the genotyping of Acanthamoeba spp. using various PCR methods is equally critical. Therefore, considering the diverse niches of habitats, it is necessary to develop an even more efficient genotyping method for Acanthamoeba spp. detection. This study improved the sensitivity of detection to avoid underestimation of Acanthamoeba spp. occurrence in aquatic environmental samples, and to accurately define the pathogenic risk by developing an efficient PCR method. In this study, a new nested genotyping method was established and compared with various PCR-based methods using in silico, lab, and empirical tests. The in silico test showed that many PCR-based methods could not successfully align specific genotypes of Acanthamoeba, except for the newly designed nested PCR and real-time PCR method. Furthermore, 52 water samples from rivers, reservoirs, and a river basin in Taiwan were analysed by six different PCR methods and compared for genotyping and detection efficiency of Acanthamoeba. The newly developed nested-PCR-based method of genotyping was found to be significantly sensitive as it could effectively detect the occurrence of Acanthamoeba spp., which was underestimated by the JDP-PCR method. Additionally, the present results are consistent with previous studies indicating that the high prevalence of Acanthamoeba in the aquatic environment of Taiwan is attributed to the commonly found T4 genotype. Ultimately, we report the development of a small volume procedure, which is a combination of recent genotyping PCR and conventional real-time PCR for enumeration of aquatic Acanthamoeba and acquirement of biologically meaningful genotyping information. We anticipate that the newly developed detection method will contribute to the precise estimation, evaluation, and reduction of the contamination risk of pathogenic Acanthamoeba spp., which is regularly found in the water resources utilised for domestic purposes.
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Leal SM, Rodino KG, Fowler WC, Gilligan PH. Practical Guidance for Clinical Microbiology Laboratories: Diagnosis of Ocular Infections. Clin Microbiol Rev 2021; 34:e0007019. [PMID: 34076493 PMCID: PMC8262805 DOI: 10.1128/cmr.00070-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The variety and complexity of ocular infections have increased significantly in the last decade since the publication of Cumitech 13B, Laboratory Diagnosis of Ocular Infections (L. D. Gray, P. H. Gilligan, and W. C. Fowler, Cumitech 13B, Laboratory Diagnosis of Ocular Infections, 2010). The purpose of this practical guidance document is to review, for individuals working in clinical microbiology laboratories, current tools used in the laboratory diagnosis of ocular infections. This document begins by describing the complex, delicate anatomy of the eye, which often leads to limitations in specimen quantity, requiring a close working bond between laboratorians and ophthalmologists to ensure high-quality diagnostic care. Descriptions are provided of common ocular infections in developed nations and neglected ocular infections seen in developing nations. Subsequently, preanalytic, analytic, and postanalytic aspects of laboratory diagnosis and antimicrobial susceptibility testing are explored in depth.
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Affiliation(s)
- Sixto M. Leal
- Department of Pathology and Laboratory Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Kyle G. Rodino
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - W. Craig Fowler
- Department of Surgery, Campbell University School of Medicine, Lillington, North Carolina, USA
| | - Peter H. Gilligan
- Pathology and Laboratory Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
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Park S, Lee K, Kang H, Lee Y, Lee J, Kim JH, Song HB, Ryu W. Single Administration of a Biodegradable, Separable Microneedle Can Substitute for Repeated Application of Eyedrops in the Treatment of Infectious Keratitis. Adv Healthc Mater 2021; 10:e2002287. [PMID: 33930253 DOI: 10.1002/adhm.202002287] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 03/22/2021] [Indexed: 11/07/2022]
Abstract
Infectious keratitis is mainly treated with topical antibiotics. To achieve and maintain the required therapeutic concentration in the cornea where the tear fluid continuously rinses the surface, the antibiotics must be frequently applied, even while the patient is sleeping, and oral medication is sometimes required. However, the inevitably poor compliance and avascular nature of the cornea decrease drug bioavailability. In this study, a single microneedle (MN) is injected into the cornea to substitute for the repeated application of eyedrops in the treatment of infectious keratitis. After comparing the mechanical integrity and drug release profiles of three different drug-tips, the drug-tip with the "high" drug concentration that releases 12.5 ng drug within 3 days is applied to a cornea to evaluate the transferability and in vivo drug release. In the treatment of infectious keratitis with repeated application of eyedrops for six consecutive days, a single MN injection is substituted for the initial 3 days of eyedrop applications. The progression remains similarly attenuated after 3 days without eyedrops, and comparable efficacy is achieved on day 6 when combined with delayed eyedrop treatment from day 3. Thus, the single administration of a biodegradable MN can substitute for the repeated application of eyedrops in the treatment of infectious keratitis.
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Affiliation(s)
- SeungHyun Park
- Department of Mechanical Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - KangJu Lee
- Department of Healthcare and Biomedical Engineering, Chonnam National University, Yeosu, 59626, Republic of Korea
| | - Heekyoung Kang
- Department of Tropical Medicine and Parasitology and Institute of Endemic Diseases, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Department of Ophthalmology, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - YeJin Lee
- Department of Mechanical Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - JiYong Lee
- Department of Mechanical Engineering, Yonsei University, Seoul, 03722, Republic of Korea
| | - Jeong Hun Kim
- Department of Tropical Medicine and Parasitology and Institute of Endemic Diseases, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Department of Ophthalmology, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - Hyun Beom Song
- Department of Tropical Medicine and Parasitology and Institute of Endemic Diseases, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080, Republic of Korea
- Department of Ophthalmology, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - WonHyoung Ryu
- Department of Mechanical Engineering, Yonsei University, Seoul, 03722, Republic of Korea
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Yera H, Ok V, Lee Koy Kuet F, Dahane N, Ariey F, Hasseine L, Delaunay P, Martiano D, Marty P, Bourges JL. PCR and culture for diagnosis of Acanthamoeba keratitis. Br J Ophthalmol 2020; 105:1302-1306. [DOI: 10.1136/bjophthalmol-2020-316730] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 08/11/2020] [Accepted: 10/03/2020] [Indexed: 11/03/2022]
Abstract
Background/AimsAcanthamoeba keratitis (AK) is a rare but sight-threatening infection. Molecular diagnosis of corneal scraping has improved the diagnosis of AK. Different molecular targets and conditions have been used in diagnosis thus far. In this study, we prospectively compared the performance of five PCR assays on corneal samples for the diagnosis of AK.Methods1217 corneal scraping samples were obtained from patients, for whom an AK was suspected. Sample processing involved both molecular diagnostics and culture. Acanthamoeba PCR assays detected different regions of the Acanthamoeba nuclear small-subunit rRNA gene: three final point PCR assays using Nelson, ACARNA and JDP1–JDP2 pairs of primers, and two real-time PCR assays using Acant primer-probe. Human DNA and internal control were co-amplified in the real-time PCR assay to ensure scraping quality and the absence of inhibitors. In the absence of a gold standard, the performance of each test was evaluated using latent class analysis. Genotypes of Acanthamoeba isolates were also characterised.ResultsEstimated prevalence of AK was 1.32%. The sensitivity of Acanthamoeba diagnostic PCRs (73.3% to 86.7%) did not differ significantly from that of culture (66.7%), or according to the target sequence or the technology. Sensitivity could be increased to 93.8% or 100% by combining two or three assays, respectively. PCR specificity (99.3% to 100%) differed between the assays. T4 was the predominant Acanthamoeba genotype (84.6%).ConclusionsCulture and a single PCR assay could lead to misdiagnosing AK. A combination of different PCR assays and improved sample quality could increase diagnosis sensitivity.
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Attariani H, Turki H, Shoja S, Salahi-Moghaddam A, Ghanbarnejad A, Shamseddin J. Investigating the frequency of free-living amoeba in water resources with emphasis on Acanthamoeba in Bandar Abbas city, Hormozgan province, Iran in 2019-2020. BMC Res Notes 2020; 13:420. [PMID: 32891184 PMCID: PMC7487464 DOI: 10.1186/s13104-020-05267-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 09/01/2020] [Indexed: 11/20/2022] Open
Abstract
Objective These amoebas can cause dangerous illnesses when they accidentally enter the human body, so it is necessary to determine various forms of organisms in water resources to prevent the danger they can cause and risks to human health. Currently, in Bandar Abbas, there is no sufficient information about the distribution of Acanthamoeba, and we intended to study its frequency and determine the related genotypes. Results Out of 83 water samples collected from different resources in the city, 31 plates (37.3%) were found to be positive for free-living amoebae. Of these, five were identified as Acanthamoeba (6%) by culture method and 8 (9.6%) by molecular method. Positive sample sequence analysis enabled us to distinguish two genotypes of T4 (7 cases) and T15 (1 case) in this study.
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Affiliation(s)
- Homa Attariani
- Molecular Medicine Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Habibollah Turki
- Molecular Medicine Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Saeed Shoja
- Infectious and Tropical Diseases Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Abdoreza Salahi-Moghaddam
- Molecular Medicine Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Amin Ghanbarnejad
- Department of Public Health, Social Determinants in Health Promotion Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
| | - Jebreil Shamseddin
- Molecular Medicine Research Center, Hormozgan Health Institute, Hormozgan University of Medical Sciences, Bandar Abbas, Iran.
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Maschio VJ, Virginio VG, Ferreira HB, Rott MB. Comparative proteomic analysis of soluble and surface-enriched proteins from Acanthamoeba castellanii trophozoites. Mol Biochem Parasitol 2018; 225:47-53. [DOI: 10.1016/j.molbiopara.2018.09.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 08/31/2018] [Accepted: 09/07/2018] [Indexed: 11/26/2022]
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Failure of molecular diagnostics of a keratitis-inducing Acanthamoeba strain. Exp Parasitol 2017; 183:236-239. [DOI: 10.1016/j.exppara.2017.09.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 09/08/2017] [Accepted: 09/11/2017] [Indexed: 11/18/2022]
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12
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Purssell A, Lau R, Boggild AK. Azithromycin and Doxycycline Attenuation of Acanthamoeba Virulence in a Human Corneal Tissue Model. J Infect Dis 2017; 215:1303-1311. [PMID: 27578848 DOI: 10.1093/infdis/jiw410] [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: 06/12/2016] [Accepted: 08/15/2016] [Indexed: 01/31/2023] Open
Abstract
Background Amoebic keratitis is a potentially blinding eye infection caused by ubiquitous, free-living, environmental acanthamoebae, which are known to harbor bacterial endosymbionts. A Chlamydia-like endosymbiont has previously enhanced Acanthamoeba virulence in vitro. We investigated the potential effect of Acanthamoeba-endosymbiont coinfection in a human corneal tissue model representing clinical amoebic keratitis infection. Methods Environmental and corneal Acanthamoeba isolates from the American Type Culture Collection were screened for endosymbionts by amplifying and sequencing bacterial 16S as well as Chlamydiales-specific DNA. Each Acanthamoeba isolate was used to infect EpiCorneal cells, a 3-dimensional human corneal tissue model. EpiCorneal cells were then treated with azithromycin, doxycycline, or control medium to determine whether antibiotics targeting common classes of bacterial endosymbionts attenuated Acanthamoeba virulence, as indicated by decreased observed cytopathic effect and inflammatory biomarker production. Results A novel endosymbiont closely related to Mycobacterium spp. was identified in Acanthamoeba polyphaga 50495. Infection of EpiCorneal cells with Acanthamoeba castellanii 50493 and A. polyphaga 50372 led to increased production of inflammatory cytokines and cytopathic effects visible under microscopy. These increases were attenuated by azithromycin and doxycycline. Conclusions Our findings suggest that azithromycin and doxycycline may be effective adjuvants to standard antiacanthamoebal chemotherapy by potentially abrogating virulence-enhancing properties of bacterial endosymbionts.
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Affiliation(s)
- Andrew Purssell
- Faculty of Medicine, University of British Columbia, Vancouver
| | | | - Andrea K Boggild
- Public Health Ontario Laboratories.,Tropical Disease Unit, Toronto General Hospital.,Department of Medicine, University of Toronto, Ontario, Canada
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13
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Karsenti N, Lau R, Purssell A, Chong-Kit A, Cunanan M, Gasgas J, Tian J, Wang A, Ralevski F, Boggild AK. Development and validation of a real-time PCR assay for the detection of clinical acanthamoebae. BMC Res Notes 2017; 10:355. [PMID: 28754142 PMCID: PMC5534048 DOI: 10.1186/s13104-017-2666-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 07/21/2017] [Indexed: 11/15/2022] Open
Abstract
Background Suboptimal agreement between molecular assays for the detection of Acanthamoeba spp. in clinical specimens has been demonstrated, and poor assay sensitivity directly imperils the vision of those affected by amoebic keratitis (AK) through delayed diagnosis. We sought to develop and validate a single Taqman real time PCR assay targeting the Acanthamoeba 18S rRNA gene that could be used to enhance sensitivity and specificity when paired with reference assays. Methods Biobanked DNA from surplus delinked AK clinical specimens and 10 ATCC strains of Acanthamoeba was extracted. Sequence alignment of 66 18S rRNA regions from 12 species of Acanthamoeba known to cause keratitis informed design of a new TaqMan primer set. Performance of the new assay was compared to the 2 assays used currently in our laboratory. Results Among 24 Acanthamoeba-positive and 83 negative specimens by the CDC reference standard, performance characteristics of the newly designed primer set were as follows: sensitivity 100%, specificity 94%, PPV 82.8%, and NPV 100%. Compared to culture, sensitivity of the new primer set was 100%, and specificity 96%. No cross-reactivity of the primer set to non-acanthamoebae, including Balamuthia and Naegleria, was found. Conclusions We have validated a real time PCR assay for the diagnosis of AK, and in doing so, have overcome important barriers to rapid and sensitive detection of acanthamoebae, including limited sensitivity and specificity of commonly used assays. Electronic supplementary material The online version of this article (doi:10.1186/s13104-017-2666-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nessika Karsenti
- Department of Molecular Genetics and Microbiology, University of Toronto, Toronto, ON, Canada
| | - Rachel Lau
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON, Canada
| | - Andrew Purssell
- Faculty of Medicine, University of British Columbia, Vancouver, Canada
| | - Ann Chong-Kit
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON, Canada
| | - Marlou Cunanan
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON, Canada
| | - Jason Gasgas
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON, Canada
| | - Jinfang Tian
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON, Canada
| | - Amanda Wang
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON, Canada
| | - Filip Ralevski
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON, Canada
| | - Andrea K Boggild
- Public Health Ontario Laboratories, Public Health Ontario, Toronto, ON, Canada. .,Tropical Disease Unit, Division of Infectious Diseases, UHN-Toronto General Hospital, 200 Elizabeth St, 13EN-218, Toronto, ON, M5G 2C4, Canada. .,Department of Medicine, University of Toronto, Toronto, Canada.
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