Acanthamoeba - Explore the Science & Experts | ideXlab

Scan Science and Technology

Contact Leading Edge Experts & Companies

Acanthamoeba

The Experts below are selected from a list of 16845 Experts worldwide ranked by ideXlab platform

Acanthamoeba – Free Register to Access Experts & Abstracts

Julia Walochnik – One of the best experts on this subject based on the ideXlab platform.

  • miltefosine and polyhexamethylene biguanide a new drug combination for the treatment of Acanthamoeba keratitis
    Clinical and Experimental Ophthalmology, 2014
    Co-Authors: Zubeyde Akin Polat, Julia Walochnik, Andreas Obwaller, Ayse Vural, Ayhan Dursun, Mustafa Kemal Arici
    Abstract:

    Background In this study, a series of compounds – miltefosine, polyhexamethylene biguanide, chlorhexidine and propamidine isetisethionate – and combinations of the latter three agents with miltefosine were prepared and used in a rat model for the topical treatment of Acanthamoeba keratitis. Methods The corneas of rats were infected with Acanthamoeba hatchetti. On the fifth day, all corneas were microscopically examined in order to determine the grade of infections. Nine groups were then prepared: miltefosine (65.12 μg/mL); chlorhexidine (0.02%); polyhexamethylene biguanide (0.02%), propamidine isetisethionate (0.1%), miltefosine plus chlorhexidine, miltefosine plus polyhexamethylene biguanide; miltefosine plus propamidine isetisethionate; infected control; and a non-infected control group. The treatment was continued for 28 days. After the treatment, the corneas were excised and used for Acanthamoeba culture to investigate the presence of Acanthamoeba growth. For the determination of cytotoxicity of the drugs on L929 cells, colorimetric assays were performed. Results The best treatment results were obtained from the polyhexamethylene biguanide plus miltefosine group; the ratio of fully recovered eyes was 28.4%. It was proven that the miltefosine–polyhexamethylene biguanide combination yielded the highest anti-Acanthamoebal activity in that approximately 86% of the eyes were cleared from amoebae. The cytotoxicity values of the miltefosine and the control groups were compared with other groups and found to be statistically different (P < 0.05). Conclusion This in vivo study demonstrates that a miltefosine–polyhexamethylene biguanide combination is highly effective for the treatment of Acanthamoeba keratitis.

  • Miltefosine and polyhexamethylene biguanide: a new drug combination for the treatment of Acanthamoeba keratitis
    Clinical & Experimental Ophthalmology, 2013
    Co-Authors: Zubeyde Akin Polat, Julia Walochnik, Andreas Obwaller, Ayse Vural, Ayhan Dursun, Mustafa Kemal Arici
    Abstract:

    Background In this study, a series of compounds – miltefosine, polyhexamethylene biguanide, chlorhexidine and propamidine isetisethionate – and combinations of the latter three agents with miltefosine were prepared and used in a rat model for the topical treatment of Acanthamoeba keratitis. Methods The corneas of rats were infected with Acanthamoeba hatchetti. On the fifth day, all corneas were microscopically examined in order to determine the grade of infections. Nine groups were then prepared: miltefosine (65.12 μg/mL); chlorhexidine (0.02%); polyhexamethylene biguanide (0.02%), propamidine isetisethionate (0.1%), miltefosine plus chlorhexidine, miltefosine plus polyhexamethylene biguanide; miltefosine plus propamidine isetisethionate; infected control; and a non-infected control group. The treatment was continued for 28 days. After the treatment, the corneas were excised and used for Acanthamoeba culture to investigate the presence of Acanthamoeba growth. For the determination of cytotoxicity of the drugs on L929 cells, colorimetric assays were performed. Results The best treatment results were obtained from the polyhexamethylene biguanide plus miltefosine group; the ratio of fully recovered eyes was 28.4%. It was proven that the miltefosine–polyhexamethylene biguanide combination yielded the highest anti-Acanthamoebal activity in that approximately 86% of the eyes were cleared from amoebae. The cytotoxicity values of the miltefosine and the control groups were compared with other groups and found to be statistically different (P 

  • Proteomic aspects of Parachlamydia Acanthamoebae infection in Acanthamoeba spp.
    The ISME Journal, 2010
    Co-Authors: David Leitsch, Michael Duchêne, Martina Köhsler, Martina Marchetti-deschmann, Andrea Deutsch, Günter Allmaier, Lena König, Barbara S Sixt, Julia Walochnik
    Abstract:

    The free-living but facultatively pathogenic amoebae of the genus Acanthamoeba are frequently infected with bacterial endosymbionts that can have a profound influence on the physiology and viability of their host. Parachlamydia Acanthamoebae , a chlamydial endosymbiont in Acanthamoebae, is known to be either symbiotic or lytic to its host, depending on the ambient conditions, for example, temperature. Moreover, parachlamydiae can also inhibit the encystment process in Acanthamoeba , an essential survival strategy of their host for the evasion of chemotherapeutic agents, heat, desiccation and radiation. To obtain a more detailed picture of the intracellular interactions of parachlamydiae and Acanthamoebae, we studied parachlamydial infection in several Acanthamoeba isolates at the proteomic level by means of two-dimensional gel gel electrophoresis (2DE) and mass spectrometry. We observed that P. Acanthamoebae can infect all three morphological subtypes of the genus Acanthamoeba and that the proteome pattern of released P. Acanthamoebae elementary bodies was always practically identical regardless of the Acanthamoeba strain infected. Moreover, by comparing proteome patterns of encysting cells from infected and uninfected Acanthamoeba cultures, it was shown that encystment is blocked by P. Acanthamoebae at a very early stage. Finally, on 2D-gels of purified P. Acanthamoebae from culture supernatants, a subunit of the NADH-ubiquinone oxidoreductase complex, that is, an enzyme that has been described as an indicator for bacterial viruvirulence was identified by a mass spectrometric and bioinformatic approach.

T K Beattie – One of the best experts on this subject based on the ideXlab platform.

  • the effect of surface treatment of silicone hydrogel contact lenses on the attachment of Acanthamoeba castellanii trophozoites
    Eye & Contact Lens-science and Clinical Practice, 2009
    Co-Authors: T K Beattie, Alan Tomlinson
    Abstract:

    OBJECTIVE: To determine if plasma surface treatment of Focus Night & Day silicone hydrogel contact lenses affects the attachment of Acanthamoeba. METHODS: Unworn lotrafilcon A contact lenses with (Focus Night & Day) and without surface treatment and Acuvue, conventional hydrogel lenses, were quartered before 90-min incubation with Acanthamoeba castellanii trophozoites. After incubation and rinsing, the trophozoites attached to one surface of each quarter were counted by direct light microscopy. Sixteen replicates were observed for each lens type. Logarithmic transformation of data allowed the use of parametric analysis of variance. RESULTS: No significant difference in attachment was established between the untreated lotrafilcon A and the conventional hydrogel lenses (P<0.001); however, surface treatment of the native Focus Night & Day material produced a significant increase in attachment (P<0.001). CONCLUSIONS: Commercially available Focus Night & Day lenses are subjected to a plasma surface treatment to reduce lens hydrophobicity; however, this procedure results in an enhanced Acanthamoebal attachment. It is possible that the silicone hydrogel lens could be at a greater risk of promoting Acanthamoeba infection if exposed to the organism because of the enhanced attachment characteristic of this material. Eye care professionals should be aware of the enhanced affinity that Acanthamoeba show for this lens and accordingly emphasise to patients the significance of appropriate lens hygiene. This is particularly important where lenses are worn in a regime that could increase the chance of exposure to the organism, i.e., 6 nights/7 days extended wear or daily wear, where lenses will be stored in a lens case, or where lenses are worn when in contact with potentially contaminated water sources, i.e., swimming or showering.

  • molecular and physiological evaluation of subtropical environmental isolates of Acanthamoeba spp causal agent of Acanthamoeba keratitis
    Journal of Eukaryotic Microbiology, 2004
    Co-Authors: Gregory C Booton, T K Beattie, Alan Tomlinson, David V Seal, Andrew Rogerson, Tonya Davidian Bonilla, Daryl J Kelly, Fernando Laresvilla, Paul A Fuerst, Thomas J Byers
    Abstract:

    Previous molecular examination of Acanthamoeba spp. has resulted in the determination of distinct genotypes in this genus (designated T1-T12, T14). Genotype T4 has been responsible for the majority of cases of Acanthamoeba keratitis. Here we examine the relative abundance of environmental T4 isolates on beaches and ask whether they have temperature and salinity tolerances that could enhance pathogenicity. Twenty-four Acanthamoeba strains were isolated from beach sand (n = 20), soil (n = 3), and tap water (n = 1) in south Florida. Phylogenetic analysis identified 19 of 24 isolates as T4, the Acanthamoeba keratitis-associated genotype. The remaining isolates were genotype T5 (4) and T11 (1). Nearly all beach isolates were genotype T4, whereas the tap water and soil isolates were mostly T5. All amoebae grew at 0, 1.0, and 2.0% salt and 19 of 20 beach isolates also grew at 3.2%. No soil or tap-water Acanthamoebae reproduced at 3.2%. All isolates grew at 37 °C and two (T5) at 42 °C. Little correlation existed between beach location, salt-tolerance, and genetic relatedness. Overall, the large majority of environmental isolates obtained were genotype T4, suggesting it may be the most common genotype in this environment and could be a potential source of Acanthamoeba keratitis infections.

  • enhanced attachment of Acanthamoeba to extended wear silicone hydrogel contact lenses a new risk factor for infection
    Ophthalmology, 2003
    Co-Authors: T K Beattie, Alan Tomlinson, Angus Mcfadyen, David V Seal, A M Grimason
    Abstract:

    Abstract Purpose To establish if silicone hydrogel (S-H) contact lenses could be a risk factor for Acanthamoeba infection by facilitating the attachment of trophozoites to their surface and transfer to the cornea and to determine the effect Acanthamoeba culture technique, patient wear, and Pseudomonas biofilm coating have on attachment to the S-H lens. Design Experimental material study. Participants and controls Attachment to a S-H lens was compared with that of a conventional hydrogel control lens. Sixteen replicates were carried out for both lens types under each test condition. Methods Unworn S-H (PureVision; Bausch & Lomb, Kingston-Upon-Thames UK) and conventional hydrogel (Acuvue; Vistakon, Johnson & Johnson, Jacksonville, FL USA) lens quarters were incubated for 90 minutes in suspensions of liquid or plate-cultured Acanthamoeba castellanii trophozoites. Unworn, worn, and Pseudomonas biofilm coated S-H and hydrogel quarters were incubated for 90 minutes with plate-cultured trophozoites. Main outcome measures Trophozoites attached to one surface of each lens quarter were counted by direct light microscopy. Logarithmic transformation of data allowed the use of a parametric analysis of variance. Results Lens polymer had a significant effect on attachment ( P P = 0.013), with higher numbers of liquid-cultured organisms attaching to both lens types. A significant increase in attachment was demonstrated with worn and Pseudomonas biofilm-coated hydrogel lenses ( P Conclusions Acanthamoebal attachment to the S-H lenses was significantly greater than to the conventional hydrogel. Liquid-cultured trophozoites demonstrated a higher affinity for the lenses tested. Wear and bacterial biofilm coating had no effect on attachment to S-H lenses. The increased attachment found with the S-H lens may be an inherent characteristic of the polymer or a side effect of the surface treatment procedure to which the lenses are exposed. It is possible that S-H lenses are at greater risk of promoting Acanthamoeba infection if exposed to the organism because of the enhanced attachment characteristic of this new material.

Alan Tomlinson – One of the best experts on this subject based on the ideXlab platform.

  • the effect of surface treatment of silicone hydrogel contact lenses on the attachment of Acanthamoeba castellanii trophozoites
    Eye & Contact Lens-science and Clinical Practice, 2009
    Co-Authors: T K Beattie, Alan Tomlinson
    Abstract:

    OBJECTIVE: To determine if plasma surface treatment of Focus Night & Day silicone hydrogel contact lenses affects the attachment of Acanthamoeba. METHODS: Unworn lotrafilcon A contact lenses with (Focus Night & Day) and without surface treatment and Acuvue, conventional hydrogel lenses, were quartered before 90-min incubation with Acanthamoeba castellanii trophozoites. After incubation and rinsing, the trophozoites attached to one surface of each quarter were counted by direct light microscopy. Sixteen replicates were observed for each lens type. Logarithmic transformation of data allowed the use of parametric analysis of variance. RESULTS: No significant difference in attachment was established between the untreated lotrafilcon A and the conventional hydrogel lenses (P<0.001); however, surface treatment of the native Focus Night & Day material produced a significant increase in attachment (P<0.001). CONCLUSIONS: Commercially available Focus Night & Day lenses are subjected to a plasma surface treatment to reduce lens hydrophobicity; however, this procedure results in an enhanced Acanthamoebal attachment. It is possible that the silicone hydrogel lens could be at a greater risk of promoting Acanthamoeba infection if exposed to the organism because of the enhanced attachment characteristic of this material. Eye care professionals should be aware of the enhanced affinity that Acanthamoeba show for this lens and accordingly emphasise to patients the significance of appropriate lens hygiene. This is particularly important where lenses are worn in a regime that could increase the chance of exposure to the organism, i.e., 6 nights/7 days extended wear or daily wear, where lenses will be stored in a lens case, or where lenses are worn when in contact with potentially contaminated water sources, i.e., swimming or showering.

  • molecular and physiological evaluation of subtropical environmental isolates of Acanthamoeba spp causal agent of Acanthamoeba keratitis
    Journal of Eukaryotic Microbiology, 2004
    Co-Authors: Gregory C Booton, T K Beattie, Alan Tomlinson, David V Seal, Andrew Rogerson, Tonya Davidian Bonilla, Daryl J Kelly, Fernando Laresvilla, Paul A Fuerst, Thomas J Byers
    Abstract:

    Previous molecular examination of Acanthamoeba spp. has resulted in the determination of distinct genotypes in this genus (designated T1-T12, T14). Genotype T4 has been responsible for the majority of cases of Acanthamoeba keratitis. Here we examine the relative abundance of environmental T4 isolates on beaches and ask whether they have temperature and salinity tolerances that could enhance pathogenicity. Twenty-four Acanthamoeba strains were isolated from beach sand (n = 20), soil (n = 3), and tap water (n = 1) in south Florida. Phylogenetic analysis identified 19 of 24 isolates as T4, the Acanthamoeba keratitis-associated genotype. The remaining isolates were genotype T5 (4) and T11 (1). Nearly all beach isolates were genotype T4, whereas the tap water and soil isolates were mostly T5. All amoebae grew at 0, 1.0, and 2.0% salt and 19 of 20 beach isolates also grew at 3.2%. No soil or tap-water Acanthamoebae reproduced at 3.2%. All isolates grew at 37 °C and two (T5) at 42 °C. Little correlation existed between beach location, salt-tolerance, and genetic relatedness. Overall, the large majority of environmental isolates obtained were genotype T4, suggesting it may be the most common genotype in this environment and could be a potential source of Acanthamoeba keratitis infections.

  • enhanced attachment of Acanthamoeba to extended wear silicone hydrogel contact lenses a new risk factor for infection
    Ophthalmology, 2003
    Co-Authors: T K Beattie, Alan Tomlinson, Angus Mcfadyen, David V Seal, A M Grimason
    Abstract:

    Abstract Purpose To establish if silicone hydrogel (S-H) contact lenses could be a risk factor for Acanthamoeba infection by facilitating the attachment of trophozoites to their surface and transfer to the cornea and to determine the effect Acanthamoeba culture technique, patient wear, and Pseudomonas biofilm coating have on attachment to the S-H lens. Design Experimental material study. Participants and controls Attachment to a S-H lens was compared with that of a conventional hydrogel control lens. Sixteen replicates were carried out for both lens types under each test condition. Methods Unworn S-H (PureVision; Bausch & Lomb, Kingston-Upon-Thames UK) and conventional hydrogel (Acuvue; Vistakon, Johnson & Johnson, Jacksonville, FL USA) lens quarters were incubated for 90 minutes in suspensions of liquid or plate-cultured Acanthamoeba castellanii trophozoites. Unworn, worn, and Pseudomonas biofilm coated S-H and hydrogel quarters were incubated for 90 minutes with plate-cultured trophozoites. Main outcome measures Trophozoites attached to one surface of each lens quarter were counted by direct light microscopy. Logarithmic transformation of data allowed the use of a parametric analysis of variance. Results Lens polymer had a significant effect on attachment ( P P = 0.013), with higher numbers of liquid-cultured organisms attaching to both lens types. A significant increase in attachment was demonstrated with worn and Pseudomonas biofilm-coated hydrogel lenses ( P Conclusions Acanthamoebal attachment to the S-H lenses was significantly greater than to the conventional hydrogel. Liquid-cultured trophozoites demonstrated a higher affinity for the lenses tested. Wear and bacterial biofilm coating had no effect on attachment to S-H lenses. The increased attachment found with the S-H lens may be an inherent characteristic of the polymer or a side effect of the surface treatment procedure to which the lenses are exposed. It is possible that S-H lenses are at greater risk of promoting Acanthamoeba infection if exposed to the organism because of the enhanced attachment characteristic of this new material.

Govinda S. Visvesvara – One of the best experts on this subject based on the ideXlab platform.

  • Characterization of a new pathogenic Acanthamoeba Species, A. byersi n. sp., isolated from a human with fatal amoebic encephalitis.
    The Journal of eukaryotic microbiology, 2013
    Co-Authors: Yvonne Qvarnstrom, Thomas A. Nerad, Govinda S. Visvesvara
    Abstract:

    Acanthamoeba spp. are free-living amoebae that are ubiquitous in natural environments. They can cause cutaneous, nasopharyngeal, and disseminated infection, leading to granulomatous amebic enceencephalitis (GAE) in immunocompromised individuals. In addition, they can cause amoebic keratitis in contact lens wearers. Acanthamoeba GAE is almost always fatal because of difficulty and delay in diagnosis and lack of optimal antimicrobial therapy. Here, we report the description of an unusual strain isolated from skin and brain of a GAE patient. The amoebae displayed large trophozoites and star-shaped cysts, characteristics for Acanthamoebas belonging to morphology Group 1. However, its unique morphology and growth characteristics differentiated this new strain from other Group 1 species. DNA sequence analysis, secondary structure prediction, and phylogenetic analysis of the 18S rRNA gene confirmed that this new strain belonged to Group 1, but that it was distinct from the other sequence types within that group. Thus, we hereby propose the establishment of a new species, Acanthamoeba byersi n. sp. as well as a new sequence type, T18, for this new strain. To our knowledge, this is the first report of a Group 1 Acanthamoeba that is indisputably pathogenic in humans.

  • Amebic Meningoencephalitis and Keratitis
    , 2011
    Co-Authors: Govinda S. Visvesvara, A J Martinez, Mary K. Klassen-fischer, Ronald C. Neafie
    Abstract:

    Abstract : Free-living amebae of the genera Naegleria, Acanthamoeba, and Balamuthia cause fatal diseases of the central nervous system (CNS) of humans.1-33 Naegleria fowleri causes an acute and fulminant primary amebic meningoencephalitis (PAM) in children and young adults with a history of exposure to fresh water leading to death within 5 to 10 days after the onset of symptoms.4-6,9,10,16,17,19,25,27,30,31,33,34 Balamuthia mandrillaris,2,3,7,8,19-22,24,26,28-31,35,36 and several species of Acanthamoeba (Acanthamoeba castellanii, Acanthamoeba culbertsoni, Acanthamoeba rhysodes, Acanthamoeba polyphaga, Acanthamoeba divionensis, Acanthamoeba healyi, and Acanthamoeba lenticulata) cause a chronic, and usually fatal, granulomatous amebic enceencephalitis (GAE) that may last for several weeks or months.1, 11,18,19,23,30,31,37-42 Acanthamoeba sp also cause an eyesight threatening infection, Acanthamoeba keratitis, in humans, especially in persons wearing contact lenses.12,15,17,19,30,31,40,43-52 Additionally, N. fowleri, Acanthamoeba sp, and B. mandrillaris also infect animals.12-17, 19,28-31, 53-58 Sappinia diploidea, another freeliving ameba identified in 200159 as an agent of meningitis, was reidentified recently as Sappinia pedata based on molecular analysis.60 So far there is only one case reported due to this ameba.

  • resistance of Acanthamoeba cysts to disinfection in multiple contact lens solutions
    Journal of Clinical Microbiology, 2009
    Co-Authors: Stephanie P Johnston, Yvonne Qvarnstrom, Rama Sriram, Sharon L Roy, Jennifer R Verani, Jonathan S Yoder, Suchita Lorick, Jacquelin M Roberts, Michael J Beach, Govinda S. Visvesvara
    Abstract:

    Acanthamoebae are free-living amoebae found in the environment, including soil, freshwater, brackish water, seawater, hot tubs, and Jacuzzis. Acanthamoeba species can cause keratitis, a painful vision-threatening infection of the cornea, and fatal granulomatous encephalitis in humans. More than 20 species of Acanthamoeba belonging to morphological groups I, II, and III distributed in 15 genotypes have been described. Among these, Acanthamoeba castellanii, A. polyphaga, and A. hatchetti are frequently identified as causing Acanthamoeba keratitis (AK). Improper contact lens care and contact with nonsterile water while wearing contact lenses are known risk factors for AK. During a recent multistate outbreak, AK was found to be associated with the use of Advanced Medical Optics Complete MoisturePlus multipurpose contact lens solution, which was hypothesized to have had insufficient anti-Acanthamoeba activity. As part of the investigation of that outbreak, we compared the efficacies of 11 different contact lens solutions against cysts of A. castellanii, A. polyphaga, and A. hatchetti (the isolates of all species were genotype T4), which were isolated in 2007 from specimens obtained during the outbreak investigation. The data, generated with A. castellanii, A. polyphaga, and A. hatchetti cysts, suggest that the two contact lens solutions containing hydrogen peroxide were the only solutions that showed any disinfection ability, with 0% and 66% growth, respectively, being detected with A. castellanii and 0% and 33% growth, respectively, being detected with A. polyphaga. There was no statistically significant difference in disinfection efficacy between the 11 solutions for A. hatchetti.

Tetsuro Oshika – One of the best experts on this subject based on the ideXlab platform.

  • Swimming with soft contact lenses: danger of Acanthamoeba keratitis
    The Lancet. Infectious diseases, 2005
    Co-Authors: Yuichi Kaji, Keisuke Kawana, Tetsuro Oshika
    Abstract:

    A 25-year-old woman sought medical advice on experiencing sudden pain and blurred vision in her right eye. She was a swimming instructor and swam with daily disposable soft contact lenses and swimming goggles. The initial diagnosis was herpetic keratitis. Topical and systemic antibiotics and aciclovir were administrated but were ineffective. When referred to Tsukuba University Hospital, she had severe eye pain and visual acuity had decreased to hand motion. Slit-lamp examination revealed corneal stromal opacity due to severe corneal inflammation (figure, A). In a corneal biopsy specimen stained with cotton blue dye, double-walled cysts compatible with Acanthamoebae were seen (figure, B). Acanthamoebae were also detected in the water of the swimming pool. Polyhexanide, amphotericin B, and levofloxacin were topically administrated. 1 month later, the corneal inflammation was reduced; however, visual acuity remained at hand motion. 1 year after treatment, the keratitis resolved and the patient’s visual acuity improved to 10/20. Acanthamoebae are found everywhere—eg, in soil, spring water, and swimming pools. Acanthamoebae are resistant to chlorine at its usual concentration in swimming pools. Thus, swimming pools could be breeding areas of Acanthamoebae. Nonetheless, Acanthamoeba keratitis is seldom contracted after swimming, possibly because blinking inhibits Acanthamoebae attaching to the corneal surface. However, once water goes into the goggles of swimmers using soft contact lenses, Acanthamoebae may come between the soft contact lenses and the cornea. In such cases, Acanthamoebae will not be removed by blinking, and the chance of Acanthamoeba keratitis increases. Soft contact lenses are indispensable to many people. A lot of people go swimming using soft contact lenses. We would like to make people aware of the risk of wearing soft contact lenses while swimming to reduce the number of patients with Acanthamoeba keratitis. Swimming with soft contact lenses: danger of Acanthamoeba keratitis