Establishment of Blastocystis hominis in-vitro Culture Using Fecal Samples from Infants in Slum Area of Mirpur, Dhaka, Bangladesh
Introduction: Blastocystis hominis (B. hominis) is an obligate anaerobic protozoan found in the human large intestine, and is the most common eukaryotic organism reported in human fecal samples. Method: Multiple stool samples from 460 children (53.9% male and 46.07% female) were collected and examined for the presence of Blastocystis hominis in Parasitology Laboratory of International Centre for Diarrhoeal Diseases Research, Bangladesh during the period of 9th January to 28th December, 2011. Among them, 255
were diarrheal patients (56.47% male and 43.53% female). Direct microscopy was done for each of the samples and each sample was cultured in vitro for 48 hours and observed again for the presence of the pathogen. The aim of the study was to develop a sustainable technique to identify the pathogen. Results: In culture, several morphological forms were observed. Through microscopy, various morphological forms were clearly observed. Within 5679 tested samples, 795 samples (0.14%) were positive for B. hominis. As multiple forms were observed in the same sample, the most prevalent was cyst (0.125%) whereas least prevalent was granular (0.0072%). The highest percentage for all the morphological forms was observed in age group 25-36 months. In direct microscopy from fresh samples, children from 37-48 months showed the highest percentage (22.9%) of infection (p=0.000). In culture, the same age group showed the most infection rate (p=0.000). Among the diff erent morphological forms observed in culture, the highest prevalence of cyst was in age group 37-48 months (p=0.000). The highest prevalence of vacuolar form(5.7%) was observed in the same age group (p=0.015).
In contrast, the amoeboid forms were mostly observed in children of 25-36 months (p=0.002).The children aged in between 37 to 48 months are at the most risk of the infection. Conclusion: The sensitivity of direct microscopy was found only 38.46% in respect to in-vitro culture which strongly suggests that in-vitro culture is the gold standard for the diagnosis of this parasite.