-
Journal of the American Veterinary... Dec 2020A 12-year-old neutered male domestic shorthair cat with chronic anterior uveitis and secondary glaucoma of the right eye was examined for persistent blepharospasm 2...
CASE DESCRIPTION
A 12-year-old neutered male domestic shorthair cat with chronic anterior uveitis and secondary glaucoma of the right eye was examined for persistent blepharospasm 2 weeks after corneal debridement and grid keratotomy for nonhealing superficial ulcerative keratitis.
CLINICAL FINDINGS
Examination of the right eye revealed a central superficial corneal ulcer associated with corneal epithelial and subepithelial infiltrates and mild aqueous flare. Structures consistent with amoeboid cysts and trophozoites were detected in the cornea by in vivo confocal microscopy. Suppurative keratitis was identified cytologically. An spp was isolated through culture and identified by a PCR assay of corneal specimens.
TREATMENT AND OUTCOME
Symptomatic and antiamoebic (polyhexamethylene biguanide 0.02% ophthalmic solution) treatments were instituted. Over the following 6 weeks, the cat lost vision in the affected eye and lesions progressed to nonulcerative stromal keratitis associated with a dense paracentral corneal stroma ring infiltrate and anterior lens luxation. The globe was enucleated, and lymphoplasmacytic sclerokeratitis, anterior uveitis, and retinal detachment were noted. organisms were detected within the corneal stroma and anterior sclera with histologic and immunohistochemical stains. The amoebae were classified to the T4 genotype by DNA sequencing. The cat had no medical problems attributed to infection over 36 months after enucleation, until the cat was lost to follow-up.
CLINICAL RELEVANCE
Naturally acquired sclerokeratitis is described in a cat for the first time. infection should be considered for cats with superficial corneal disease refractory to appropriate treatments and especially occurring after ocular trauma, including keratotomy.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Animals; Cat Diseases; Cats; Cornea; Corneal Stroma; Corneal Ulcer; Male
PubMed: 33269959
DOI: 10.2460/javma.257.12.1280 -
Biomedicine & Pharmacotherapy =... Feb 2023Free Living Amoeba (FLA) infections caused by Acanthamoeba genus include chronic nervous system diseases such as Granulomatous Amoebic Encephalitis (GAE), or a severe...
Free Living Amoeba (FLA) infections caused by Acanthamoeba genus include chronic nervous system diseases such as Granulomatous Amoebic Encephalitis (GAE), or a severe eye infection known as Acanthamoeba keratitis (AK). Current studies focused on therapy against these diseases are aiming to find novel compounds with amoebicidal activity and low toxicity to human tissues. Brown algae, such as Gongolaria abies-marina (previously known as Cystoseira abies-marina, S.G. Gmelin), presents bioactive molecules of interest, including some with antiprotozoal activity. In this study, six meroterpenoids were isolated and purified from the species Gongolaria abies-marina. Gongolarones A (1), B (2) and C (3) were identified as new compounds. Additionally, cystomexicone B (4), 1'-methoxyamentadione (5) and 6Z-1'-methoxyamentadione (6) were isolated. All compounds exhibited amoebicidal activity against Acanthamoeba castellanii Neff, A. polyphaga and A. griffini strains. Gongolarones A (1) and C (3) showed the lowest IC values against the two stages of these amoebae (trophozoite and cyst). Structure-activity relationship revealed that the cyclization by ether formation from C-12 to C-15 of 1, and the isomerization Δ to Δ of 3, increased the antiamoeboid activity of both compounds. Furthermore, gongolarones A (1) and C (3) triggered chromatin condensation, mitochondrial malfunction, oxidative stress, and disorganization of the tubulin-actin cytoskeleton in treated trophozoites. Moreover, transmission electron microscopy (TEM) images analysis revealed that compounds 1 and 3 induced autophagy process and inhibited the encystation process. All those results suggest that both compounds could induce programmed cell death (PCD) in Acanthamoeba.
Topics: Animals; Humans; Acanthamoeba castellanii; Amebicides; Trophozoites; Actin Cytoskeleton
PubMed: 36916403
DOI: 10.1016/j.biopha.2022.114185 -
Middle East African Journal of... 2019Natural honey in spite of its usefulness is known to contain certain microorganisms. In the present study, we describe a case of after using topical honey administered...
Natural honey in spite of its usefulness is known to contain certain microorganisms. In the present study, we describe a case of after using topical honey administered by a traditional medicine therapist. A 32-year-old male came with red eye and blurred vision. The pain and other symptoms became more severe after the 1st week, with appearance of radial perineuritis at the cornea. A repeated interview revealed that 1 week before appearance of ocular symptoms, the patient had instilled a drop of natural honey in his left eye. Confocal microscopic cornea imaging demonstrated cyst and trophozoite of in the corneal stroma.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Adult; Honey; Humans; Male; Vision Disorders
PubMed: 32153338
DOI: 10.4103/meajo.MEAJO_56_18 -
International Journal of Molecular... Apr 2022To date, no studies have addressed the role of neurotrophins (NTs) in spp. infections in the brain. Thus, to clarify the role of NTs in the cerebral cortex and...
To date, no studies have addressed the role of neurotrophins (NTs) in spp. infections in the brain. Thus, to clarify the role of NTs in the cerebral cortex and hippocampus during experimental acanthamoebiasis in relation to the host immune status, the purpose of this study was to determine whether spp. may affect the concentration of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4) in brain structures. Our results suggest that at the beginning of infection in immunocompetent hosts, BDNF and NT-3 may reflect an endogenous attempt at neuroprotection against spp. infection. We also observed a pro-inflammatory effect of NGF during acanthamoebiasis in immunosuppressed hosts. This may provide important information for understanding the development of cerebral acanthamoebiasis related to the immunological status of the host. However, the pathogenesis of brain acanthamoebiasis is still poorly understood and documented and, therefore, requires further research.
Topics: Acanthamoeba; Amebiasis; Brain; Brain-Derived Neurotrophic Factor; Humans; Nerve Growth Factor; Nerve Growth Factors; Neurotrophin 3
PubMed: 35563321
DOI: 10.3390/ijms23094931 -
Parasitology Research Sep 2022Intron retention (IR) refers to the mechanism of alternative splicing in which an intron is not excised from the mature transcript. IR in the cosmopolitan free-living...
Intron retention (IR) refers to the mechanism of alternative splicing in which an intron is not excised from the mature transcript. IR in the cosmopolitan free-living amoeba Acanthamoeba castellanii has not been studied. We performed an analysis of RNA sequencing data during encystment to identify genes that presented differentially retained introns during this process. We show that IR increases during cyst formation, indicating a potential mechanism of gene regulation that could help downregulate metabolism. We identify 69 introns from 67 genes that are differentially retained comparing the trophozoite stage and encystment after 24 and 48 h. These genes include several hypothetical proteins. We show different patterns of IR during encystment taking as examples a lipase, a peroxin-3 protein, an Fbox domain containing protein, a proteasome subunit, a polynucleotide adenylyltransferase, and a tetratricopeptide domain containing protein. A better understanding of IR in Acanthamoeba, and even other protists, could help elucidate changes in life cycle and combat disease such as Acanthamoeba keratitis in which the cyst is key for its persistence.
Topics: Acanthamoeba Keratitis; Acanthamoeba castellanii; Animals; Humans; Introns; Life Cycle Stages; Trophozoites
PubMed: 35776211
DOI: 10.1007/s00436-022-07578-5 -
Journal of Water and Health Oct 2023Different species of free-living amoeba (FLA) have been abundantly isolated in harsh environmental conditions such as hot springs and brackish water. The present study...
Different species of free-living amoeba (FLA) have been abundantly isolated in harsh environmental conditions such as hot springs and brackish water. The present study aimed to isolate, genotype, and evaluate the pathogenicity of FLAs in Qom Roud, a large river, in the centre of Iran. About 500 mL of water samples (n = 30) were collected from each sampling site and were investigated for the presence of FLAs using morphological and molecular characters. Genotype identification was performed using DNA sequencing and a phylogenetic tree was constructed with the MEGA X software. The pathogenic potential of all positive isolates was evaluated using the tolerance ability test. Morphological and molecular analysis indicated that 14 (46.66%) and two (6.66%) water samples were positive for Acanthamoeba species and Vahlkampfiidae, respectively. According to sequence analysis, Acanthamoeba isolates related to the T4 genotype and Vahlkampfiidae sequences were similar to Naegleria philippinensis. In the next step, thermo- and osmotolerance tests indicated four Acanthamoeba strains are extremely pathogenic. Our data showed the presence of potentially pathogenic Acanthamoeba T4 genotype and N. philippinensis in the super harsh Qom Roud. Contamination of water with virulent T4 genotype of Acanthamoeba may pose risk factors for contact lens users, children, and immunocompromised people.
Topics: Child; Humans; Acanthamoeba; Iran; Genotype; Phylogeny; Water
PubMed: 37902210
DOI: 10.2166/wh.2023.203 -
Experimental Parasitology Jan 2020Acanthamoeba 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... (Review)
Review
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.
Topics: Acanthamoeba; Central Nervous System Protozoal Infections; Genotype; Granuloma; Humans; Immunocompetence; Immunocompromised Host; Infectious Encephalitis
PubMed: 31647916
DOI: 10.1016/j.exppara.2019.107788 -
Infectious Disorders Drug Targets 2020Encephalitis caused by Free-living amoebae (FLA) has a mortality rate of around 95- 98%, a fraction that has not changed in the past decades. Pathogenic FLA include... (Review)
Review
Encephalitis caused by Free-living amoebae (FLA) has a mortality rate of around 95- 98%, a fraction that has not changed in the past decades. Pathogenic FLA include Acanthamoeba, Balamuthia mandrillaris, and Naegleria fowleri that are known to target the brain after an extra cerebral infection in the case of Acanthamoeba and Balamuthia mandrillaris, or directly the brain, as in the case of the Naegleria fowleri. The Acanthamoeba spp. and Balamuthia mandrillaris cause granulomatous amoebic encephalitis (GAE) while Naegleria fowleri, the so termed "brain eating amoeba" causes primary amoebic meningoencephalitis (PAM). The attempts to obtain a speedy diagnosis and an aggressive treatment protocol are the areas where advances can make a difference and reduce the mortality rates. At first, we highlight the reasons behind the diagnostic delays and treatment failures and provide proposals to establish a quick diagnosis in both PAM and GAE. Secondly, we emphasize the use of a transcribrial device, and a prompt, but vigilant surgical reduction of the intracranial pressure in these patients which could be life-saving. We also debate that an exudate obtained from the olfactory region by irrigation via a modified transcribrial device or by conventional methods, instead of a cerebrospinal fluid sample, could serve as a source of obtaining amoeba in PAM for a real-time polymerase chain reaction-based definitive diagnosis of PAM. Also, introduced is the rationale that has the potential to deliver the drugs to the brain in patients with PAM and the GAE localized to the frontal lobe of the brain, by bypassing the blood brain barrier. We put forward these proposals for debate and deliberation to our fellow colleagues in order to spot the potential of their application to reduce the mortality rates caused by the rare but fatal encephalitis caused by these FLA.
Topics: Acanthamoeba; Amebiasis; Antiprotozoal Agents; Balamuthia mandrillaris; Brain; Central Nervous System Protozoal Infections; Encephalitis; Humans; Naegleria fowleri
PubMed: 30961516
DOI: 10.2174/1871526519666190405170601 -
Proceedings of the National Academy of... Sep 2022Protists are important regulators of microbial communities and key components in food webs with impact on nutrient cycling and ecosystem functioning. In turn, their...
Protists are important regulators of microbial communities and key components in food webs with impact on nutrient cycling and ecosystem functioning. In turn, their activity is shaped by diverse intracellular parasites, including bacterial symbionts and viruses. Yet, bacteria-virus interactions within protists are poorly understood. Here, we studied the role of bacterial symbionts of free-living amoebae in the establishment of infections with nucleocytoplasmic large DNA viruses (Nucleocytoviricota). To investigate these interactions in a system that would also be relevant in nature, we first isolated and characterized a giant virus (Viennavirus, family Marseilleviridae) and a sympatric potential host infected with bacterial symbionts. Subsequently, coinfection experiments were carried out, using the fresh environmental isolates as well as additional amoeba laboratory strains. Employing fluorescence in situ hybridization and qPCR, we show that the bacterial symbiont, identified as , represses the replication of the sympatric Viennavirus in both recent environmental isolates as well as laboratory strains. In the presence of the symbiont, virions are still taken up, but viral factory maturation is inhibited, leading to survival of the amoeba host. The symbiont also suppressed the replication of the more complex and (Mimiviridae). Our work provides an example of an intracellular bacterial symbiont protecting a protist host against virus infections. The impact of virus-symbiont interactions on microbial population dynamics and eventually ecosystem processes requires further attention.
Topics: Amoeba; Ecosystem; Giant Viruses; In Situ Hybridization, Fluorescence; Mimiviridae; Symbiosis
PubMed: 36037367
DOI: 10.1073/pnas.2205856119 -
European Journal of Protistology Jun 2024Acanthamoeba castellanii (Douglas, 1930) Page, 1967 is the type species of a widespread genus of free-living amoebae, potentially pathogenic for humans and animals. The...
Acanthamoeba castellanii (Douglas, 1930) Page, 1967 is the type species of a widespread genus of free-living amoebae, potentially pathogenic for humans and animals. The Neff strain is one of the most widely used in biological research, serving as a model for both A. castellanii and the whole genus in general. The Neff strain, isolated in California, closely resembles another strain found in France and originally described as a separate species, Acanthamoeba terricola Pussard, 1964, but both were successively synonymized with A. castellanii. Molecular sequence analysis has largely replaced morphological diagnosis for species identification in Acanthamoeba, and rDNA phylogenies show that the Neff strain forms a distinct lineage from that of the type strain of A. castellanii. In this study, we compared the type strain of A. terricola with the Neff strain and A. castellanii, and analysed the available molecular data including new sequences obtained from A. terricola. Here we provide molecular evidence to validate the species A. terricola. The Neff strain is therefore transferred to A. terricola and should no longer be considered as belonging to A. castellanii.
Topics: Phylogeny; Acanthamoeba; DNA, Protozoan; DNA, Ribosomal; Species Specificity; Sequence Analysis, DNA; Molecular Sequence Data; Animals
PubMed: 38772052
DOI: 10.1016/j.ejop.2024.126091