Acanthamoeba Keratitis in Non-Contact Lens Wearers

Spaeth, George L.; Chang, Patricia Chuen-Tsuei; Soong, H. Kaz

doi:10.1001/archopht.1991.01080040023004

Cited by 14 publications

(5 citation statements)

References 2 publications

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“…epithelial cells) do not develop this infection (Niederkorn et al , 1999). Nevertheless, corneal trauma followed by exposure to contaminated water, soil or other vector (inert objects or biological surfaces such as unclean hands) is sufficient, resulting in Acanthamoeba keratitis and is the most likely cause of Acanthamoeba keratitis in noncontact lens wearers (Sharma et al , 1990; Chang & Soong, 1991). The requirement of corneal trauma can be explained by the fact that the expression of Acanthamoeba ‐reactive glycoprotein(s) on damaged corneas is 1.8 times higher than on healthy corneas, suggesting that corneal injury contributes to Acanthamoeba infection (Jaison et al , 1998).…”

Section: Acanthamoeba Keratitis (From Contact Lens To Cornea)mentioning

confidence: 99%

“…Even in susceptible species, corneal injury is a prerequisite for Acanthamoeba keratitis, and animals that have intact epithelial layers do not develop Acanthamoeba keratitis (Niederkorn et al , 1999). The importance of corneal injury is demonstrated further by reports that injury to the surface of the cornea, even with a splash of Acanthamoeba ‐contaminated water, can lead to Acanthamoeba keratitis in individuals who do not wear contact lenses (Sharma et al , 1990; Chang & Soong, 1991). It has been shown that the expression of Acanthamoeba ‐reactive glycoproteins(s) on surface‐damaged corneal epithelial cells is significantly higher than on the surface of normal corneal epithelial cells, suggesting that corneal injury contributes markedly to Acanthamoeba keratitis (Jaison et al , 1998).…”

Section: Acanthamoeba Keratitis (From Contact Lens To Cornea)mentioning

confidence: 99%

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Acanthamoeba: biology and increasing importance in human health

2006

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Acanthamoeba is an opportunistic protozoan that is widely distributed in the environment and is well recognized to produce serious human infections, including a blinding keratitis and a fatal encephalitis. This review presents our current understanding of the burden of Acanthamoeba infections on human health, their pathogenesis and pathophysiology, and molecular mechanisms associated with the disease, as well as virulence traits of Acanthamoeba that may be targets for therapeutic interventions and/or the development of preventative measures.

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Section: Acanthamoeba Keratitis (From Contact Lens To Cornea)mentioning

confidence: 99%

Section: Acanthamoeba Keratitis (From Contact Lens To Cornea)mentioning

confidence: 99%

Acanthamoeba: biology and increasing importance in human health

2006

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“…Improper sterilization procedures have been identified as the cause of a large percentage of such AK infections (2,22,25). In developing nations, AK infections are not generally associated with contact lens wear; by contrast, most cases are the result of ocular trauma (6,23).…”

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confidence: 99%

Identification and Distribution of Acanthamoeba Species Genotypes Associated with Nonkeratitis Infections

Booton¹,

et al. 2005

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Acanthamoeba is a free-living protozoan genus found in a wide variety of natural habitats, including water, soil, and air. Pathogenic isolates of Acanthamoeba are medically relevant as the causative agent of sight-threatening Acanthamoeba keratitis (AK), serious infections of other organs, and fatal granulomatous amebic encephalitis. Previous work employing DNA sequences of nuclear and mitochondrial small-subunit rRNA genes (SSU rRNA genes) determined the genotypic diversity of Acanthamoeba and found that many named species of Acanthamoeba are associated with particular genotypes. These studies also concluded that nearly all AK infections result from a single molecular genotype: T4. Here, we asked whether Acanthamoeba clinical isolates from non-AK infections are also associated with particular genotypes. DNA sequence determination of nuclear SSU rRNA genes was employed for genotypic identification of 29 isolates of Acanthamoeba from non-AK infections. Sequence analysis demonstrates that T4 is the predominant genotype in non-AK infections, including those in brain, cerebrospinal fluid, nasal passages, skin, and lung. Rare genotypes (T1, T10, and T12) have been isolated from brain infections. We conclude that genotype T4 is the primary genotype in non-AK Acanthamoeba infections, as was the case in AK infections. However, the genotypes that were isolated from brains have not been observed in environmental isolates of Acanthamoeba, and their natural ecological niche is unknown.The genus Acanthamoeba is a group of nearly 25 named species that has a worldwide distribution. Members of Acanthamoeba are naked (i.e., lacking tests, walls, or tecta with openings), free-living amebae that inhabit a wide range of natural ecological niches, including fresh and brackish water, beach sand, soil, air, etc. (4, 13, 16, 17). Acanthamoeba also has been isolated from humans and animals (16,18). In addition to its natural distribution, Acanthamoeba can be opportunistically pathogenic, being identified as the causative agent of a painful and sight-threatening infection of the cornea, Acanthamoeba keratitis (AK) (22). These infections can occur in otherwise healthy, nonimmunocompromised individuals. In developed countries, AK infections are usually associated with contact lens wear. Improper sterilization procedures have been identified as the cause of a large percentage of such AK infections (2, 22, 25). In developing nations, AK infections are not generally associated with contact lens wear; by contrast, most cases are the result of ocular trauma (6, 23).Acanthamoeba is also responsible for life threatening infections in patients with immunodeficiency disease. These include documented infections of the skin, nasal passages, lung, and brain (16,17,18,19). In the brain, Acanthamoeba causes a severe encephalitis termed granulomatous amebic encephalitis, which is nearly always fatal (18). Variations in the pathogenicity of different Acanthamoeba strains have been recognized in laboratory studies, but the relevance of these results to hum...

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“…Upon insertion into the eye, the contact lens disrupts tear flow over the eye, leaving a thin layer of fluid trapped between the lens and the ocular surface; any Acanthamoeba present in this layer can penetrate the corneal epithelium causing infection. In non‐contact lens wearers, the primary risk factors for AK infection are through ocular trauma and/or eye contact with water (Chang and Soong 1991; Illingworth and Cook 1998; Sharma et al 1990). …”

Section: Discussionmentioning

confidence: 99%

Molecular and Physiological Evaluation of Subtropical Environmental Isolates of Acanthamoeba spp., Causal Agent of Acanthamoeba Keratitis

Booton

Rogerson

Bonilla

et al. 2004

J Eukaryotic Microbiology

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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 degrees C and two (T5) at 42 degrees 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.

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Acanthamoeba Keratitis in Non-Contact Lens Wearers

Cited by 14 publications

References 2 publications

Acanthamoeba: biology and increasing importance in human health

Acanthamoeba: biology and increasing importance in human health

Identification and Distribution of Acanthamoeba Species Genotypes Associated with Nonkeratitis Infections

Molecular and Physiological Evaluation of Subtropical Environmental Isolates of Acanthamoeba spp., Causal Agent of Acanthamoeba Keratitis

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