ISSN: 0973-7510

E-ISSN: 2581-690X

Research Article | Open Access
Amal F. Makled1, Mabrouk M. Ghonaim1, Sahar A.M. Ali1, Sally Mohammed ElHefnawy2, Mona Salah Sabal1 and Asmaa Mohammed Elbrolosy1
1Department of Medical Microbiology & Immunology, Faculty of Medicine, Menoufia University, Egypt.
2Department of Medical Biochemistry and Molecular Biology, Faculty of Medicine, Menoufia University, Egypt.
J Pure Appl Microbiol. 2022;16(2):1337-1349 | Article Number: 7597
https://doi.org/10.22207/JPAM.16.2.62 | © The Author(s). 2022
Received: 05/02/2022 | Accepted: 09/05/2022 | Published online: 01/06/2022
Issue online: June 2022
Abstract

Accurate identification of fungal causes for onychomycosis is essential for proper treatment. Presently available laboratory methods show unreliable sensitivity; so there is a requirement for innovative detection techniques. The aim for this work was to assess the efficiencies of fluorescent staining and internal transcribed spacer (ITS) ribosomal DNA (rDNA) polymerase chain reaction (PCR)-based sequencing in comparison to conventional techniques for diagnosis of onychomycosis. Nail specimens obtained from 100 patients with clinically- diagnosed onychomycosis were analyzed. Nail scrapings or clippings were subjected to direct microscopic examination by KOH mount, culture by using Sabouraud’s dextrose agar and histopathological examination with periodic-acid Schiff (PAS). Collected specimens were subsequently examined by fluorescent staining and PCR-based sequencing (30 specimens only) to compare the feasibility, sensitivity and diagnostic accuracy for these two methods. The most frequently isolated fungi were yeasts (39/76: 51.3%), dermatophytes (24/76; 31.6%) and non-dermatophyte molds (NDMs) (13/76; 17.1%). Mixed mycotic infections were recovered from 6% of the collected nail specimens. The positive detection rates were significantly different between KOH examinations (52%), nail plate histology (55%), fungal culture (70%) and fluorescent staining (80%). Considering fungal culture as the gold standard, the most sensitive technique was PCR (100%) followed by fluorescent staining (89%), PAS staining (69%) while the least sensitive technique was KOH mount (53%). Fluorescence staining can be used as a rapid and high-yield technique for identification of fungi in the specimens. PCR-based sequencing was highly sensitive and faster compared to culture. Whenever possible, it enables species identification with higher adequacy.

Keywords

Onychomycosis, Direct KOH mount, Fluorescent staining, Fungal culture, PCR-based sequencing

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© The Author(s) 2022. Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License which permits unrestricted use, sharing, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.