Publication: Comparison of nested PCR and culture identification of Pythium insidiosum in patients with Pythium keratitis
Issued Date
2016-09-01
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01252208
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2-s2.0-85006991666
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Mahidol University
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SCOPUS
Bibliographic Citation
Journal of the Medical Association of Thailand. Vol.99, No.9 (2016), 1033-1038
Suggested Citation
Panida Kosrirukvongs, Angkana Chaiprasert, Chayamon Canyuk, Wanchai Wanachiwanawin Comparison of nested PCR and culture identification of Pythium insidiosum in patients with Pythium keratitis. Journal of the Medical Association of Thailand. Vol.99, No.9 (2016), 1033-1038. Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/41165
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Title
Comparison of nested PCR and culture identification of Pythium insidiosum in patients with Pythium keratitis
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Abstract
© 2016, Medical Association of Thailand. All rights reserved. Background: Delayed diagnosis can lead to the development of endophthalmitis and blindness, which is difficult to manage because of the lack of an effective antimicrobial agent. Objective: Comparing the nested polymerase chain reaction (PCR) technique with the standard diagnostic culture method for Pythium insidiosum. Material and Method: Eighty-three patients with suspected fungal keratitis were enrolled in this observational, cross-sectional study from the Faculty ofMedicine Siriraj Hospital between February 2011 and February 2014. Patient symptoms, associated diseases, duration of ulcers, precipitating causes, best-corrected visual acuity, intraocular pressure, and other clinical findings were recorded. Corneal scrapings were taken for Gram staining, bacterial and fungal cultures, staining with potassium hydroxide preparation, and DNA extraction for nested PCR. The sensitivity, specificity, accuracy, and agreement of the nested PCR analysis and culture diagnosis of P. insidiosum were compared. Results: Five patients had a positive result for nested PCR amplification of P. insidiosum, while only one of these was also positive for culture growth of Pythium. Nested PCR sensitivity was 50% (95% confidence interval [95% CI] 1.3-98.7), specificity 94.7% (95% CI 86.9-98.5), and accuracy 93.5% (95% CI 85.7-97.2) with a fair agreement (kappa 0.258, p = 0.011). Conclusion: Therefore, nested PCR may be an appropriate test for P. insidiosum in diagnosing Pythium keratitis with high accuracy, despite small amounts of corneal specimen.