Acanthamoeba castellanii
Dongyou Liu in Handbook of Foodborne Diseases, 2018
The pathogenic Acanthamoeba spp. cause rare infections in humans with the patients with AK dominating over cases of GAE, and pulmonary and skin infection. These unicellular eukaryotes are of clinical significance in cases of diseases that come under the headings of immunosuppressive states or are the ones that make the person weak enough to mount an effective immune response. It is imperative that these infections should be avoided whenever possible from water and foodborne sources that are infected with Acanthamoeba. More research is needed to develop rapid diagnostic methods and treatment protocols to help cases with GAE and AK. Identification of Acanthamoeba in food resources needs to be further investigated, as we do not know the incidences of the infection of skin and soft tissue that could result from this source to patients with AIDS and patients suffering from other immune deficiency–related disorders. More insights are needed to know the source of these FLA detected on vegetables and beans and whether the water contamination is seeding them on food resources or they prey on foods like vegetables and beans. Answers to these questions are expected to clarify the infections caused by FLA from food resources and help prevent diseases related to them.
Water-based disease and microbial growth *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
Almost any source of warm water is a likely source of Legionella. Outbreaks have been associated with cooling towers, warm groundwater, hot water heaters, shower heads, hot tubs, humidifiers, ornamental fountains, thermal springs, misters, etc. Legionellae are more resistant to chlorine than Escherichia coli, and can grow in waters at temperatures between 25 and 45oC. It can be controlled in hot water systems by raising the temperature of hot water heaters to over 60 oC and to 50 oC at outlets combined with regular flushing of the distribution system. Legionella has been shown to be present in drinking water systems even when exposed to 0.75 mg/L of free chlorine, as it commonly resides within a protective microbial biofilm and can be protected by its intracellular association with protozoa such as Acanthamoebaspp. (Buse et al., 2012; Thomas and Ashbolt, 2011). Legionellais addressed specifically in Chapter 8.
Acanthamoeba
Dongyou Liu in Laboratory Models for Foodborne Infections, 2017
To enhance its detection and identification, Acanthamoeba is grown on NNA, 1.5% containing a lawn of E. coli or E. aerogenes, axenically in PYG medium (2% proteose peptone, 0.2% yeast extract, and 0.1 M glucose), or in Oxoid medium (Cline medium, containing serum and hemin) at 28°C–35°C for 10 days or more (to allow sufficient time for excystment). Alternatively, Acanthamoeba may be cultured on mammalian cell monolayers [e.g., African green monkey kidney (Vero), human embryonic lung (HEL), human embryonic kidney (HEK), HeLa, B103 rat neuroblastoma, and L929 fibroblasts]. Acanthamoeba ingestion of bacteria or cells produces clear plaques after a week. Microscopic examination of Acanthamoeba culture isolates provides valuable confirmation [2].
Epidemiology of free-living amoebae in the Philippines: a review and update
Published in Pathogens and Global Health, 2022
Giovanni D. Milanez, Frederick R. Masangkay, Gregorio L. Martin I, Ma. Frieda Z Hapan, Edilberto P. Manahan, Jeffrey Castillo, Panagiotis Karanis
Despite the reported diversity of FLA and pathogenic genotypes in various environmental sources in the country (Figure 3), reports on morbidity and/or mortality cases of FLA-related infections remain largely unknown. Acanthamoeba keratitis (AK) was first reported in the country in 1992 [33]. Between 2002 and 2004, three more cases of AK were reported [35]. In 2009, a 76-years-old male reported pain, redness, and visual impairment of the right eye where molecular testing confirmed Acanthamoeba genotype T4 [36]. It is important to note that all these AK cases involved non-contact lens wearers and that the latter case used tap water to cleanse the face before the onset of symptoms. Surprisingly, in the study of Cruz and Rivera (2014), 4.4% (8/180) of nasal swabs from asymptomatic volunteers were positive with Acanthamoeba spp. T4 and T5 [3]. The proposed transmission route was obviously from the chronic exposure of the volunteers to garbage, soil, and dust as part of their everyday activity. In this case, it is interesting to speculate on the potential health outcomes in the event of depression or suppression of the immune system of the Acanthamoeba-positive volunteers. Also, it opens up perspectives into the health hazards on FLA-related infections faced by high-exposure groups of laborers working in unsanitary conditions and environments. Also, the predominance of Acanthamoeba genotype T4 and T5 in local human cases was potentially influenced by the propensity of the same genotypes reported in the highest frequencies in local environmental sources.
Current understanding and therapeutic management of contact lens associated sterile corneal infiltrates and microbial keratitis
Published in Clinical and Experimental Optometry, 2021
Lily Ho, Isabelle Jalbert, Kathleen Watt, Alex Hui
In the United Kingdom, Acanthamoeba keratitis is suggested as more common than fungal keratitis.61 Studies from the United Kingdom have reported a strong association of contact lens wear with Acanthamoeba keratitis, with approximately 90% of Acanthamoeba keratitis attributed to contact lens wear and most cases having identifiable risk factors such as poor contact lens disinfection, swimming, and/or bathing while wearing the contact lenses.62–64 An Australian study found 80% of Acanthamoeba keratitis cases presenting to Sydney Eye Hospital occur in contact lens wearers, within which poor hygiene attributed additional risk.65 Contact with contaminated water remains the major risk for Acanthamoeba keratitis.31,64
Acanthamoeba Keratitis: Perspectives for Patients
Published in Current Eye Research, 2021
Stefano Bonini, Antonio Di Zazzo, Giuseppe Varacalli, Marco Coassin
The high rate of patients with late-stage AK suggests a current trend of misdiagnosis, which ultimately affects patient care and prognosis. A prompt diagnosis and start of therapeutic treatment significantly improves corneal healing and reduces the risk of surgical procedures. Here, we report that corneal ulcers induced by Acanthamoeba require a mean time of 12.5 months to heal and to restore the ocular surface. Patients presenting with severe corneal ulcers require an even longer treatment. In addition, we show that patients with severe AK had longer follow-ups compared to patients with stage I or II. Our data confirm previous reports by Carnt et al.22 indicating that patients with AK require 10 months of treatment with 38 months of follow-up and a mean number of 31 visits to restore their ocular surface. In spite of this, they may end up with poor vision requiring corneal transplantation.23 In our study 41% of all patients, although treated, required a corneal surgical procedure, probably due to a higher paracentral incidence of AK in stage II and I. In fact, among enrolled eyes, 46.8% were severe cases with corneal rings and intense inflammation. Patients with mild (stage I) or moderate (stage II) disease had a better prognosis and final outcome. Thus, an early diagnosis improves the visual outcome and reduces the need for additional surgeries.24,25
Related Knowledge Centers
- Acanthamoeba Keratitis
- Amoeba
- Neurological Disorder
- Protease
- Trophozoite
- Cerebral Edema
- Microbial Cyst
- Granulomatous Amoebic Encephalitis
- Immunodeficiency
- Lupus