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Gayathri Ramasubban, Lily Therese, Bagyalakshmi Radhakrishnan, Hajib Madhavan; Rare and newer Non Sporulating Moulds emerging as corneal pathogens identified by molecular techniques in a Tertiary Eye Care Centre. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2896. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To report on the identification of Non Sporulating Moulds (NSM) isolated from Corneal ulcers / keratitis by PCR based DNA sequencing targeting ITS region in a tertiary eye care centre.
A total of 151 fungal isolates from 813 corneal specimens (608 corneal scraping and 155 corneal buttons) processed for Microbiological investigations from suspected cases of corneal ulcer/ keratitis during January 2012 to November 2012 were included in the study. Among the 151 fungal isolates, 21 (13.9%) were Non Sporulating Moulds (NSM). In order to identify the NSM to species level, standardised PCR based DNA sequencing targeting Internal transcribed spacer region (ITS region) was applied on DNA extracted from the 21 NSM followed by BLAST analysis.
Out of the 21 NSM, 14 were from corneal scrapings and 7 were from corneal buttons. PCR based DNA sequencing targeting ITS region resulted in identification of 9 NSM as Pythium insidiosum (Corneal scraping-5, Corneal button-4), 5 as Lasiodiplodia theobromae (Corneal scraping-3, Corneal button-2), 2 as Mortierella wolffi (from 1 corneal scraping and 1 corneal button of the same patient) and 1 each of Lasiodiplodia pseudotheobromae, Colletotrichum species, Humicola fuscota and Chaetomium species in 5 corneal scrapings. The NSM identification to species level was possible within 36-48 hours by PCR based DNA sequencing.
PCR based DNA sequencing is a rapid, reliable tool to identify the NSM to species level. Pyhtium insidiosum was the most common fungus identified followed by Lasiodiplodia theobromae in this study. To the best our knowlwdge this is the first report on Colletotrichum species as the causative agent of keratitis and Mortierella wolffi as the human pathogen.
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