Modified fields’ stain: ideal to differentiate Dientamoeba fragilis and Blastocystis sp.
Dientamoeba fragilis, a trichomonad parasite is usually found in the gastrointestinal tract of human, and it is known to be the cause for gastrointestinal disease. The parasite is globally distributed and mostly found in rural and urban areas. The parasite is found in humans and nonhuman primates such as the macaques, baboons, and gorillas. Often, the parasite is confused with another largely found organism in stools called Blastocystis sp. especially when seen directly under light microscopy on culture samples containing both parasites. Both sometimes are seen with two nuclei with sizes tending to be similar which complicates identification. Stools were collected fresh from nine previously diagnosed persons infected with D. fragilis who also were found to be positive for Blastocystis sp. Samples were then cultured in Loeffler’s medium and were stained with Giemsa, iron hematoxylin, and modified Fields’ (MF) stain, respectively. D. fragilis was differentiated from Blastocystis sp. when stained with MF stain by the presence of a thinner outer membrane with clearly demarcated nuclei in the center of the cell whilst Blastocystis sp. had a darker and thicker stained outer membrane with the presence of two nuclei. The staining contrast was more evident with modified Fields’ stain when compared with the other two. The simplicity in preparing the stain as well as the speed of the staining procedure make MF stain an ideal alternate. The modified Fields’ stain is faster and easier to prepare when compared to the other two stains. MF stain provides a better contrast differentiating the two organisms and therefore provides a more reliable diagnostic method to precisely identify one from the other especially when cultures show mixed infections.
KeywordsModified fields’ stain Parasite Dientamoeba fragilis Blastocystis sp. Differentiation
The study would not have been possible without the support of HIR grant UM.C/625/1/HIR/044 and student grant PG095-2013B
Financial competing interest
The authors declare that they have no competing interests.
ADR and SKG were involved in all stages of the study, including concept and design of the experiment, data collection and analysis, and interpretation of results. ADR wrote up the manuscript, and all authors read and approved the finalized manuscript.
Department of Parasitology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia
Conflict of interest
The authors have no conflict of interest. The authors do not have a commercial or other association that has a conflict of interest.
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