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Journal of Infection and Public Health Jun 2023Acanthamoeba keratitis is a rare parasitic infection of the cornea that can lead to permanent blindness if not diagnosed and treated promptly. We collected data on the... (Review)
Review
Acanthamoeba keratitis is a rare parasitic infection of the cornea that can lead to permanent blindness if not diagnosed and treated promptly. We collected data on the incidences of Acanthamoeba keratitis from 20 countries and calculated an annual incidence of 23,561 cases, with the lowest rates in Tunisia and Belgium, and the highest in India. We analyzed 3755 Acanthamoeba sequences from the GenBank database across Asia, Europe, North America, South America, and Oceania and genotyped them into T1, T2, T3, T4, T5, T10, T11, T12, and T15. Many genotypes possess different characteristics, yet T4 is the most prevalent genotype. As efficient treatment against Acanthamoeba remains lacking, prevention from early diagnosis via staining, PCR, or in vivo confocal microscopy (IVCM) becomes significant for the condition's prognosis. IVCM is the most recommended approach for the early detection of Acanthamoeba. If IVCM is unavailable, PCR should be used as an alternative.
Topics: Humans; Acanthamoeba Keratitis; Acanthamoeba; Cornea; Genotype; Prognosis
PubMed: 37030037
DOI: 10.1016/j.jiph.2023.03.020 -
The New England Journal of Medicine Jul 2019
Topics: Acanthamoeba; Acanthamoeba Keratitis; Adult; Cornea; Female; Humans
PubMed: 31314971
DOI: 10.1056/NEJMicm1817678 -
Neuropathology : Official Journal of... Aug 2019Over 600 cases of amoebic encephalitis caused by pathogenic free-living amoebas (Balamuthia mandrillaris, Acanthamoeba spp., and Naegleria fowleri) have been reported... (Review)
Review
Over 600 cases of amoebic encephalitis caused by pathogenic free-living amoebas (Balamuthia mandrillaris, Acanthamoeba spp., and Naegleria fowleri) have been reported worldwide, and in Japan, 24 cases have been reported from the first case in 1976 up to 2018. Among these cases, 18 were caused by B. mandrillaris, four by Acanthamoeba spp., one by N. fowleri, and one was of unknown etiology. Additionally, eight cases were diagnosed with encephalitis due to pathogenic free-living amoebas before death, but only three cases were successfully treated. Unfortunately, all other cases were diagnosed by autopsy. These facts indicate that an adequate diagnosis is difficult, because encephalitis due to pathogenic free-living amoebas does not show typical symptoms or laboratory findings. Moreover, because the number of cases is limited, other cases might have been missed outside of those diagnosed by autopsy. Cases of encephalitis caused by B. mandrillaris have been reported from all over Japan, with B. mandrillaris recently isolated from soil in Aomori prefecture. Therefore, encephalitis caused by pathogenic free-living amoebas should be added to the differential diagnosis of encephalitis patients.
Topics: Acanthamoeba; Amebiasis; Balamuthia mandrillaris; Central Nervous System Protozoal Infections; Encephalitis; Humans; Japan; Naegleria fowleri
PubMed: 31243796
DOI: 10.1111/neup.12582 -
Experimental Parasitology Aug 2022Acanthamoeba castellanii is a free-living protozoan that causes several severe human parasitic diseases such as Acanthamoeba keratitis and granulomatous encephalitis. A....
Acanthamoeba castellanii is a free-living protozoan that causes several severe human parasitic diseases such as Acanthamoeba keratitis and granulomatous encephalitis. A. castellanii feeds on bacteria, yeasts, and other organic particles as food sources, but the mechanisms of digestion in acanthamoebal cells are unclear. Rab GTPases participate in endosomal delivery in eukaryotes after phagocytosis. This study aimed to determine the potential functions of A. castellanii Rab7 (AcRab7), which is involved in phagocytosis, and the relationship between AcRab7 and further cellular physiological phenomena. In this study, the inhibitor CID1067700 (CID) was used to specifically inhibit the binding of nucleotides to confirm the potential functions of AcRab7. Cellular proliferation and ATP assays were also used to detect underlying cellular physiological functions after blocking the phagocytosis pathway. We found that AcRab7 expression increased as the co-culture time with Escherichia coli increased. Immunofluorescence staining showed that AcRab7 colocalized with lysosomes in its GTP-activating form. In addition, AcRab7 inhibition resulted in a reduction in cell proliferation and ATP levels. Our results suggest that AcRab7 participates in endosomal delivery and dominates energy production and cell growth.
Topics: Acanthamoeba Keratitis; Acanthamoeba castellanii; Adenosine Triphosphate; Escherichia coli; Humans; Phagocytosis
PubMed: 35738459
DOI: 10.1016/j.exppara.2022.108312 -
Parasitology Research Aug 2021Efficacious treatments against Acanthamoeba Keratitis (AK) is challenging, often ineffective and linked to the intragenotype variation in the drug efficacy. Increased...
Efficacious treatments against Acanthamoeba Keratitis (AK) is challenging, often ineffective and linked to the intragenotype variation in the drug efficacy. Increased oxygen can facilitate host response and can inhibit some organisms. Herein, we report the effect of increased oxygen concentrations on Acanthamoeba spp. growth and its effect on ROS (reactive oxygen species) production. The exposition to pure oxygen could reduce cell growth by at least 60% for Acanthamoeba castellanii Neff, Acanthamoeba polyphaga, and Acanthamoeba griffini. The increase in ROS production confirming that oxygen cell's growth inhibition was due to oxidative stress. Further studies are needed to determine oxygen saturation level, time of oxygen exposition, and number of sessions needed to eliminate the parasite.
Topics: Acanthamoeba castellanii; Oxidative Stress; Oxygen; Reactive Oxygen Species
PubMed: 34251514
DOI: 10.1007/s00436-021-07219-3 -
Trends in Parasitology Mar 2022Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba spp. can cause devastating brain infections in humans which almost always result in death. The symptoms of... (Review)
Review
Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba spp. can cause devastating brain infections in humans which almost always result in death. The symptoms of the three infections overlap, but brain inflammation and the course of the disease differ, depending on the amoeba that is responsible. Understanding the differences between these amoebae can result in the development of strategies to prevent and treat these infections. Recently, numerous scientific advancements have been made in the understanding of pathogenicity mechanisms in general, and the basic biology, epidemiology, and the human immune response towards these amoebae in particular. In this review, we combine this knowledge and aim to identify which factors can explain the differences between the lethal brain infections caused by N. fowleri, B. mandrillaris, and Acanthamoeba spp.
Topics: Acanthamoeba; Amebiasis; Amoeba; Balamuthia mandrillaris; Encephalitis; Humans; Naegleria fowleri
PubMed: 34758928
DOI: 10.1016/j.pt.2021.10.004 -
Trends in Parasitology Nov 2022The opportunistic protist Acanthamoeba, which interacts with other microbes such as bacteria, fungi, and viruses, shows significant similarity in cellular and functional... (Review)
Review
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.
Topics: Acanthamoeba; Bacteria; Fungi; Humans; Macrophages; Phagocytes
PubMed: 36109313
DOI: 10.1016/j.pt.2022.08.007 -
International Journal of Antimicrobial... Oct 2020Acanthamoebae are facultative parasites causing rare but serious infections such as keratitis and encephalitis and are also known as vectors for several bacterial...
Acanthamoebae are facultative parasites causing rare but serious infections such as keratitis and encephalitis and are also known as vectors for several bacterial pathogens, including legionellae and pseudomonads. Acanthamoeba cysts are particularly resilient and enable the amoebae to withstand desiccation and to resist disinfection and therapy. While the search for new therapeutic options has been intensified in the past years, hand and surface disinfectants as well as topical antiseptics for preventing infections have not been studied in detail to date. The aim of this study was to screen well-known and commonly used antimicrobial products in various formulations and different concentrations for their efficacy against Acanthamoeba trophozoites and cysts, including aliphatic alcohols, quaternary ammonium compounds (QACs), peracetic acid (PAA), potassium peroxymonosulfate sulfate (PPMS) and octenidine dihydrochloride (OCT). Of all products tested, OCT and QACs showed the highest efficacy, totally eradicating both trophozoites and cysts within 1 min. The determined 50% effective concentration (EC) for cysts was 0.196 mg/mL for OCT and 0.119 mg/mL for QACs after 1 min of exposure. PAA and PPMS showed reliable cysticidal efficacies only with prolonged incubation times of 30 min and 60 min, respectively. Aliphatic alcohols generally had limited efficacy, and only against trophozoites. In conclusion, OCT and QACs are potent actives against Acanthamoeba trophozoites and cysts at concentrations used in commercially available products, within contact times suitable for surface and hand disinfection as well as topical antisepsis.
Topics: Acanthamoeba; Acanthamoeba Keratitis; Alcohols; Antiparasitic Agents; Disinfectants; Disinfection; Hand Disinfection; Humans; Imines; Peracetic Acid; Pyridines; Quaternary Ammonium Compounds; Sulfuric Acids; Trophozoites
PubMed: 32739477
DOI: 10.1016/j.ijantimicag.2020.106122 -
Tropical Biomedicine Jun 2022Pathogenic free-living amoebae (FLA), namely Acanthamoeba sp., Naegleria fowleri and Balamuthia mandrillaris are distributed worldwide. These neurotropic amoebae can... (Review)
Review
Pathogenic free-living amoebae (FLA), namely Acanthamoeba sp., Naegleria fowleri and Balamuthia mandrillaris are distributed worldwide. These neurotropic amoebae can cause fatal central nervous system (CNS) infections in humans. This review deals with the demographic characteristics, symptoms, diagnosis, and treatment outcomes of patients with CNS infections caused by FLA documented in India. There have been 42, 25, and 4 case reports of Acanthamoeba granulomatous amoebic encephalitis (GAE), N. fowleri primary amoebic meningoencephalitis (PAM), and B. mandrillaris meningoencephalitis (BAE), respectively. Overall, 17% of Acanthamoeba GAE patients and one of the four BAE patients had some form of immunosuppression, and more than half of the N. fowleri PAM cases had history of exposure to freshwater. Acanthamoeba GAE, PAM, and BAE were most commonly seen in males. Fever, headache, vomiting, seizures, and altered sensorium appear to be common symptoms in these patients. Some patients showed multiple lesions with edema, exudates or hydrocephalus in their brain CT/MRI. The cerebrospinal fluid (CSF) of these patients showed elevated protein and WBC levels. Direct microscopy of CSF was positive for amoebic trophozoites in 69% of Acanthamoeba GAE and 96% of PAM patients. One-fourth of the Acanthamoeba GAE and all the BAE patients were diagnosed only by histopathology following autopsy/biopsy samples. Twenty-one Acanthamoeba GAE survivors were treated with cotrimoxazole, rifampicin, and ketoconazole/amphotericin B, and all eleven PAM survivors were treated with amphotericin B alongside other drugs. A thorough search for these organisms in CNS samples is necessary to develop optimum treatment strategies.
Topics: Acanthamoeba; Amebiasis; Amoeba; Amphotericin B; Balamuthia mandrillaris; Central Nervous System Infections; Humans; Male
PubMed: 35838101
DOI: 10.47665/tb.39.2.017 -
Contact Lens & Anterior Eye : the... Aug 2023Acanthamoeba spp. are pathogens that cause Acanthamoeba keratitis (AK), a serious cornea inflammation that can lead to gradual loss of vision, permanent blindness, and... (Review)
Review
Acanthamoeba spp. are pathogens that cause Acanthamoeba keratitis (AK), a serious cornea inflammation that can lead to gradual loss of vision, permanent blindness, and keratoplasty. The efficacy of AK treatment depends on the drug's ability to reach the target tissue by escaping the protective eye barrier. No single drug can eradicate the living forms of the amoeba and be non-toxic to the cornea tissue. The treatment aims to eradicate both forms of protozoan life but is hampered by the resistance of the cysts to the most available drugs, leading to prolonged infection and relapses. Drug therapy is currently performed mainly using diamidines and biguanides, as they are more effective against cysts. However, they are cytotoxic to corneal cells. Drugs are applied topically, and hourly. Over time, the frequency of administration decreases, but the treatment time varies from month to years. This study aims to obtain an up-to-date summary of the literature since 2010, allowing us to identify the trends and gaps and address future research involving new alternatives for treating AK. The results were divided into three phases, pre-treatment, empirical treatment, and the treatment after diagnosis confirmation. The drugs prescribed were stratified into antiamoebic, antibiotic, antifungal, antivirals, and steroids. It was possible to observe the transition in drug prescription during three different stages until the diagnosis was confirmed. There were more indications for antibiotic, antifungal, and antiviral drugs in the early stages of the disease. The antiamoebic drugs were only prescribed after exhausting other treatments. This can be directly involved in developing complications and no responsiveness to medical treatment.
Topics: Humans; Acanthamoeba Keratitis; Antifungal Agents; Acanthamoeba; Cornea; Anti-Bacterial Agents
PubMed: 37117130
DOI: 10.1016/j.clae.2023.101844