Detection of Blastocystis sp. in stool samples by different diagnostic methods

Abstract

Blastocystis sp. is an intestinal parasite that is commonly identified in asymptomatic individuals, as its pathogenic role is underestimated. In Syria, studies on this parasite are very few, and it is not documented in the laboratory reports. The present study aimed to evaluate the sensitivity of three different diagnostic methods in the detection of Blastocystis spp. among patients with non-specific gastrointestinal symptom. Stool samples were collected from 70 patients suffering from various gastrointestinal symptoms. All samples were examined microscopically using iodine staining smears, and after in vitro cultivation at 37°C for 48- 72 h using Jones' medium. Molecular detection of Blastocystis sp. was determined by fragment amplification of the SSU rRNA gene using PCR. Blastocystis sp. was identified in:  49 cases (70%) by direct microscopic examination, in 60 isolate (85.7%) by in vitro culture and in 64 (91.4%) of cases using molecular detection. Comparative analysis revealed that the sensitivity of microscopic detection for Blastocystis sp. was 73.4% while it was 90.6% for in vitro culture and approximately 96.7% using PCR detection method. Blastocystis sp. was found alone in 32 (65.3%) of cases, while co-infection was detected in 17 (34.7%) samples. Our findings highlighted the importance of considering Blastocystis sp. in laboratory diagnosis. Molecular methods are recommended for screening clinical specimens for Blastocystis sp. infection especially among individuals with no common particular symptoms. If not applicable, two different diagnostic techniques are required for accurate diagnose of this parasite.