Blastocystis is the most frequently isolated protozoan parasite from human faeces. The cyst is the only form that responsible for infection via faeco-oral route. It has been known to be associated with immuno-compromised patients.

The present study aimed to detect Blastocystis species (spp.) in different immuno-compromised groups by using two different diagnostic techniques.

In this cross sectional study, 200 Stool samples were collected from four groups, (group I): Patients with cancer, (group II): Patients with uncontrolled diabetes mellitus (DM), (group III): Patients with chronic renal diseases and (group IV): healthy people used as a control. Samples were examined microscopically by direct wet mount technique and after culture on Jones̕ medium.

The percentage of Blastocystis spp. positive samples detected by direct microscopy was higher in the immuno-compromised groups than in the healthy control one (83.3% and 40% respectively). This percentage was increased after culture to be (96% and 60% respectively) with statistical significant (P value < 0.001) in immuno-compromised groups. culture method showed a higher sensitivity and lower specificity than the direct microscopy. Among different immuno-compromised groups, group I, II and III, the percentage of Blastocystis spp. positive samples detected by direct microscopy was higher when compared to (group IV) the healthy control (86%, 90%, 74% and 40% respectively). This percentage was increased after culture to be (96%, 98%, 94% and 60% respectively) with statistical significant in group III (P value 0.014) when comparing between the two different diagnostic methods. However, there was no statistical significant difference among different immuno-compromised groups.