A study of the spectrum of  Acanthamoeba  keratitis: A three-year study at a tertiary eye care referral center in South India

Bharathi, Jayahar M; Srinivasan, Muthiah; Ramakrishnan, Rengappa; Ravindran, Meenakshi; Padmavathy, S.; Lalitha, Prajna

doi:10.4103/0301-4738.29493

Cited by 55 publications

(84 citation statements)

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“…Similar data were reported in other studies [10,[15][16][17]19]. Srinivasan et al [8] attributed their negative culture rate of 20% to the topical antibiotic medication used before evaluation.…”

Section: Discussionsupporting

confidence: 87%

“…The presence of hypopyon was very low compared with other studies [8,19]; this information is probably underestimated in our series. It is not surprising that we saw an association between hypopyon and positive culture, since it characterizes a severe infection with intraocular involvement.…”

Section: Discussioncontrasting

confidence: 74%

“…However, some studies in developing countries identify ocular trauma as the leading risk factor in infectious keratitis, attributing little importance to contact lens wear [8,10,11,15,19]. In our sample, 12.5% of patients wore contact lenses and 16.3% suffered ocular trauma.…”

Section: Discussionmentioning

confidence: 92%

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Microbial keratitis at a referral center in Brazil

Cariello

Passos

et al. 2011

Int Ophthalmol

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To describe the epidemiological and laboratory characteristics of microbial keratitis at a referral center in Brazil. Charts of all patients referred to the Ocular Microbiology Laboratory at Federal University of São Paulo (UNIFESP) from July 1975 to September 2007 were retrospectively reviewed. The following data were recorded: age, gender, involved eye, use of ocular medication, previous trauma or surgery, contact lens wear and the results of laboratory cultures. The study included 6,804 corneal cultures. The mean age was 42.1 ± 21.4 years. The male-to-female ratio was 1.5:1. Positive cultures were obtained in 3,309 (48.6%) cases. Of these, bacteria were isolated in 2,699 (39.7%), fungi in 364 (5.3%) and Acanthamoeba in 246 (3.6%) samples. Positive bacterial cultures were 2.7-fold more frequent in patients with previous use of steroids (P < 0.01), and a 30% reduction in positive bacterial cultures was observed in patients with previous use of antibiotics (P < 0.01). A total of 1,524 patients (22.4%) had a past history of ocular surgery. Contact lens wearers showed a 1.7 times greater chance of having an Acanthamoeba-positive culture (P < 0.01). Previous ocular trauma was present in 1,118 (16.4%) cases and injury caused by plants showed a 3.8 times greater chance of a positive fungal culture (P < 0.01). Bacterial organisms were identified as the most frequent agent followed by fungi and Acanthamoeba. Prescription of steroids and antibiotics prior to corneal scrapings may modify the laboratory test results. Previous corneal surgery, contact lens wear and ocular trauma have been shown to be risk factors for bacterial, Acanthamoeba and fungal keratitis, respectively.

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Section: Discussionsupporting

confidence: 87%

Section: Discussioncontrasting

confidence: 74%

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Microbial keratitis at a referral center in Brazil

Cariello

Passos

et al. 2011

Int Ophthalmol

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“…In recent years the prevalence of Acanthamoeba keratitis has increased rapidly in developed countries in contact lens wearers (Dart et al, 2009;Patel & Hammersmith, 2008). In developing countries like India, Acanthamoeba infections are widely reported in non-contact lens wearers rather than contact lens wearers, with a history of ocular trauma, exposure to falling dust particles, use of contaminated water or bad hygienic practices (Bharathi et al, 2007;Lalitha et al, 2012;Pasricha et al, 2003). Sporadic cases of Acanthamoeba keratitis have been reported from different parts of India (Manikandan et al, 2004;Sharma et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Genotyping of Acanthamoeba spp. and characterization of the prevalent T4 type along with T10 and unassigned genotypes from amoebic keratitis patients in India

Behera

Panda

Satpathy

et al. 2016

Journal of Medical Microbiology

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Free-living amoebae of the genus Acanthamoeba are the causative agents of severe sightthreatening infection of the cornea. This study was designed to characterize the genotype of 20 Acanthamoeba spp. isolates obtained from corneal scrapings of 183 suspected Acanthamoeba keratitis patients reporting to the Outpatient Department/Casualty Services of Dr R. P. Centre for Ophthalmic Sciences, All India Institute of Medical Sciences, New Delhi, India during the period 2011-2015. Corneal scrapings were inoculated onto 2 % non-nutrient agar plates overlaid with Escherichia coli and incubated at 30 8C for 15 days. Amongst 183 suspected Acanthamoeba keratitis patients, 29 were found culture-positive for Acanthamoeba spp. out of which 20 samples were established in axenic culture for molecular analysis. DNA was isolated and PCR assay was performed for the amplification of the diagnostic fragment 3 (DF3) (,280 bp) region of the 18S rRNA gene from axenic culture of 20 Acanthamoeba spp. isolates. Rns genotyping was performed on the basis of variation in nucleotide sequences of the DF3 region of the 18S rRNA gene. In the phylogenetic analysis, 16 of the 20 isolates were found to be of prevalent genotype T4, two were of genotype T10 and the remaining two isolates were of unassigned genotypes. Hence, it was concluded that genotype T4 was found as the most predominant genotype involved in Acanthamoeba keratitis infections. Genotype T10, which had not been reported from India, was detected for the first time in two patients. Two isolates were found to be unique, which shared ,95 % homology with all the known genotypes (T1-T20) of Acanthamoeba spp.

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“…Although the worldwide increased prevalence of AK is predominantly caused by the improper use or care of contact lenses (CL), other risk factors and environmental exposures associated with AK should be considered. Moreover, non-contact lens wearers have been diagnosed with AK, leading to a need for more study [4] .…”

Section: Research Articlementioning

confidence: 99%

Identification of Acanthamoeba Membrane Protein That is Recognized by TLR4 on Corneal Epithelial Cells

Tripathi

Abdi

Alizadeh

2015

Receptor Clin Invest

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We have shown that Acanthamoeba spp. activate TLR4 on corneal epithelial cells and induce secretion of chemokines. However, the components of Acanthamoeba trophozoites that induce chemokines production remain unknown. We sought to identify the trophozoite molecules that interact with TLR4 on human corneal epithelial (HCE) cells and trigger IL-8 production. Acanthamoeba membrane protein (AcMP) was isolated by homogenization of trophozoites. The supernatants were collected, solubilized, and membrane fractions were separated by centrifugation using Mem-PER TM plus kit. To examine functional activity of AcMP, HCE and TLR4-expressing HEK293 cells were incubated with or without A. castellanii (1×10 5 cells/ml) and AcMP (10, 25, and 50 µg/ml) for 24 hours. AcMP was chromatographed by fast protein liquid chromatography (FPLC) and fractions were pooled into four peaks (AcMP-P1 -AcMP-P4). TLR4-ligand in AcMP-P1 -AcMP-P4 was determined by Western blotting. HEK293 and HCE cells were incubated with or without A. castellanii, lipopolysaccharide (LPS, 10 µg/ml), and AcMP-P1 -AcMP-P4 (20 µg/ml) for 24 hours. qRT-PCR and ELISA were used to examine the ability of AcMP-P1 -AcMP-P4 to stimulate IL-8 production in HEK293 and HCE cells. Inhibition of TLR4 involved preincubating HEK293 and HCE cells for 1 hour with neutralizing TLR4-antibody (10 µg/ml) or with the control antibody (10 µg/ml, goat serum) followed by incubation with or without A. castellanii, LPS, and AcMP-P2 for 24 hours. AcMP induced significant IL-8 production at doses of 10, 25, and 50 µg/ml in HEK293 cells while IL-8 mRNA expression and IL-8 secretion were significantly increased in HCE cells at the dose of 50 µg/ml. Treatments of HEK293 with FPLC chromatographed trophozoites' proteins, AcMP-P1 -AcMP-P4; only AcMP-P2 upregulated significant IL-8 production and mRNA expression. Western blotting of AcMP-P1 -AcMP-P4 showed TLR4-antigen in AcMP-P2 and was recognized an approximate 15-kDa protein band. Anti-TLR4 antibody attenuated IL-8 secretion that is stimulated by AcMP-P2 from HEK293 and HCE cells. These results suggest that A. castellanii trophozoites recognize TLR4 on HCE and HEK293 cells by an approximate 15-kDa molecular mass protein of AcMP and induce IL-8 secretion.

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A study of the spectrum of Acanthamoeba keratitis: A three-year study at a tertiary eye care referral center in South India

Cited by 55 publications

References 0 publications

Microbial keratitis at a referral center in Brazil

Microbial keratitis at a referral center in Brazil

Genotyping of Acanthamoeba spp. and characterization of the prevalent T4 type along with T10 and unassigned genotypes from amoebic keratitis patients in India

Identification of Acanthamoeba Membrane Protein That is Recognized by TLR4 on Corneal Epithelial Cells

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