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. 2022 Jul-Dec;12(2):87-93.
doi: 10.4103/tp.tp_93_21. Epub 2022 Nov 24.

Evaluation of microscopy and PCR for detection of Dientamoeba fragilis

Mona Mohamed Tolba  1 , Amal Farahat Allam  1 , Safia Saleh Khalil  1 , Wagdy Makram Elshouki  2 , Amel Youssef Shehab  1
Affiliations

Evaluation of microscopy and PCR for detection of Dientamoeba fragilis

Mona Mohamed Tolba et al. Trop Parasitol. 2022 Jul-Dec.

Abstract

Introduction: Dientamoeba fragilis (D. fragilis) diagnosis is an intestinal protozoan parasite globally found in rural and urban areas and is attracting a growing interest. Its prevalence in stool varies from 0.2% to more than 19% depending upon the population studied.

Materials and methods: This study was based on the examination of 100 stool samples of randomly referred cases in a rural area in Motobus district, Kafr El-Sheikh governorate, Egypt. Our aim was to investigate the presence of D. fragilis in stool of the examined individuals using conventional polymerase chain reaction (PCR) compared to wet mount and trichrome stain with confirmation of infection by transmission electron microscopy.

Results: D. fragilis was detected in 13/100 of the stool samples examined using wet mount smears, while trichrome stain detected 17/100. Conventional PCR diagnosed 41 cases of D. fragilis in the studied group. A very good agreement was found between wet mount and trichrome stain for diagnosing D. fragilis, while there was fair agreement between conventional PCR and both microscopy methods. Transmission electron microscope was performed on pooled positive samples that revealed the internal structures of D. fragilis trophozoite with its characteristic nucleus.

Conclusions: PCR technique was superior to microscopy for the detection of D. fragilis. Trichrome stain remains vital for microscopic diagnosis.

Keywords: Conventional polymerase chain reaction; Dientamoeba fragilis; diagnosis; trichrome stain; wet mount.

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Conflict of interest statement

There are no conflicts of interest.

Figures

Figure 1
Figure 1
Dientamoeba fragilis trophozoite using wet mount (magnification, ×400)
Figure 2
Figure 2
Dientamoeba fragilis trophozoite with trichrome stain (oil immersion, magnification, ×1000)
Figure 3
Figure 3
Gel electrophoresis of Dientamoeba fragilis PCR with primers DF1 and DF4. Lanes 1, 2, 3, 4: 662 bp bands specific for Dientamoeba fragilis SSu rRNA. Lane N: Negative control, Lane M: DNA marker
Figure 4
Figure 4
TEM showing mononucleated Dientamoeba fragilis trophozoite. N: nucleus. Dv: digestive vacuole, L: lysosome, Ph: phagosome
See this image and copyright information in PMC

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