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Pathogenic potential of Blastocystis hominis in laboratory mice
Hala S Elwakil1, Iman H Hewedi
1Department of Parasitology, Faculty of Medicine, Ain Shams University, Ramsis St., Abbassia, Cairo, Egypt. hasa66@hotmail.com
Abstract:
Blastocystis hominis is a ubiquitous enteric protozoan whose pathogenic potential is still controversial. This study was carried out to clarify the pathogenecity of B. hominis infection and to study the proper number of parasites for mice infection. A total of 15 albino mice were orally inoculated with B. hominis and divided according to the inoculums, 10(2), 10(5), and 4 x 10(7) B. hominis forms/100 microl saline, into three groups consisting of five mice each, GI, GII GIII, respectively. In addition with group IV (uninfected control) consisting of five mice. All mice were sacrificed 2 weeks post-infection. The results revealed that all mice of GIII and two mice of GII got the infection while all mice of GI showed a completely negative result. Histopathological examination of large intestine on highly infected group (GIII) showed that B. hominis infiltrated the lamina propria, the submucosa, and the muscle layers in the form of collection of vacuolar forms. This was accompanied by active colitis with infiltration of mixed inflammatory cells. In conclusion, this study revealed that large number of B. hominis is essential for oral infection of mice and that vacuolar forms of B. hominis can invade the lamina propria, the submucosa, and even the muscle layers.
Insights
High Blastocystis hominis parasite counts are essential for successful oral infection in mice. Vacuolar forms can invade intestinal layers, causing colitis.
Area of Science:
- Microbiology
- Parasitology
- Gastroenterology
Background:
- Blastocystis hominis is a common intestinal protozoan.
- Its role in causing disease (pathogenicity) remains debated.
Purpose of the Study:
- To determine the pathogenicity of Blastocystis hominis infection.
- To establish the minimum parasite load required for successful infection in a mouse model.
Main Methods:
- Mice were orally inoculated with varying concentrations of Blastocystis hominis (10^2, 10^5, and 4x10^7 forms).
- Infection levels were assessed, and infected mice underwent histopathological examination of the large intestine.
- Control groups of uninfected mice were included.
Main Results:
- Infection was only established in mice receiving high doses (10^5 and 4x10^7 forms).
- Mice with high-dose infections showed Blastocystis hominis in the lamina propria, submucosa, and muscle layers.
- Histopathology revealed active colitis with inflammatory cell infiltration in heavily infected mice.
Conclusions:
- A high inoculum of Blastocystis hominis is necessary for oral infection in mice.
- Blastocystis hominis, particularly vacuolar forms, can penetrate deep into the intestinal wall layers.
- These findings contribute to understanding Blastocystis hominis pathogenicity.
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