Utility of polymerase chain reaction for rapid diagnosis of pediatric fungal keratitis : A comparative study with conventional mycological work up

Shymaa Yahia,Wesam Mokhtar,Ghada Mokhtar,Sahar Hemeda

doi:10.21608/mid.2020.47773.1079

Shymaa Yahia, Wesam Mokhtar + Show 2 more

Open Access

https://doi.org/10.21608/mid.2020.47773.1079

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Abstract

Background: Fungal keratitis (FK) is a serious infection with bad complications in paediatric population. Thus, rapid diagnosis is necessary. Early diagnosis is a beneficial tool necessary for better management and prognosis of FK and also for prevention of subsequent complications such as endophthalmitis, amblyopia ,and loss of vision . In recent years, polymerase chain reaction became the predominant diagnostic method for mycotic keratitis, being frequently employed for complementing microbiological approaches.The aim of this study to determine the risk factors of paediatric fungal keratitis and evaluate the utility of polymerase chain reaction (PCR) in diagnosis by comparing its sensitivity and specificity with conventional fungal culture (the gold standard ).Methods: corneal scrapings obtained from clinical suspected patients with fungal keratitis and subjected to direct microscopic examination with 10% KOH, gram smear, fungal culture and conventional PCR using common probe to all fungi. Results: The most prominent predisposing factor for FK was ocular trauma (n=40, 57%) followed by vernal keratoconjunctivitis (n=14, 20%). Out of the 70 studied cases featuring presumed fungal keratitis, 35 were culture positive (50%), with Fusarium spp. (48.5%) and Aspergillus spp. (20%) were the predominant isolates. By comparing fungal culture (the gold standard) versus10 % KOH examination, Gram smear, and PCR were 57.1%, 28.6%, and 97.1%, respectively. Conclusion Ocular trauma and vernal keratoconjunctivitis are the most common risk factors for pediatrics fungal keratitis with Fusarium spp. and Aspergillus spp. are the most common isolated fungi. PCR is a sensitive technique for diagnosing of paediatric patients with fungal keratitis.

Highlights

Fungal keratitis (FK) is a dangerous type of keratitis with the worst visual prognosis, as it may result in blindness [1]
By comparison between the three different techniques with culture,which considered the gold standard for diagnosing of fungal keratitis, utilized to establish diagnosis we reported that direct microscopic examination using 10% KOH possess sensitivity, specificity, a positive predictive and a negative predictive value as of 57.1%, 100%, 100%, respectively
Our study showed a male predominance (n=40, 57%), which is similar to other previous studies [20,21,22], and this may be due to increased contact with ocular trauma as main predisposing element for FK

Summary

Introduction

Fungal keratitis (FK) is a dangerous type of keratitis with the worst visual prognosis, as it may result in blindness [1]. The aim of this study to determine the risk factors of paediatric fungal keratitis and evaluate the utility of PCR in diagnosis by comparing its sensitivity and specificity with conventional fungal culture (the gold standard). Methods: Corneal scrapings obtained from clinical suspected patients with FK and subjected to direct microscopic examination with 10% KOH, Gram smear, fungal culture and conventional PCR using common probe to all fungi. By comparing fungal culture (the gold standard) versus 10 % KOH examination, Gram smear, and PCR were 57.1%, 28.6%, and 97.1%, respectively. Conclusion: Ocular trauma and vernal keratoconjunctivitis are the most common risk factors for pediatrics FK with Fusarium spp. and Aspergillus spp. are the most common isolated fungi. Polymerase chain reaction is a sensitive technique for diagnosing paediatric patients with FK

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