Clinical significance and frequency of Blastocystis hominis in Turkish patients with hematological malignancy

The effect of Blastocystis hominis (B. hominis) in both immunocompetent and immunocompromised subjects has been the subject of debate in recent years, mostly in response to its unknown pathogenicity and frequency of occurrenc e. We performed a non-randomised, open labelled, single institute study in our hospital in order to investigate the clinical significance and frequenc y of B. hominis in patients suffering from hematological malignancy (HM) wh o displayed symptoms of gastrointestinal diseases during the period of chem otherapy-induced neutropenia. The presence and potential role of other inte stinal inclusive of parasites were also studied. At least 3 stool samples f rom each of 206 HM patients with gastrointestinal complaints (the HM group) were studied. These were compared with stool samples from a control group of 200 patients without HM who were also suffering from gastrointestinal co mplaints. Samples were studied with saline-lugol, formalin-ether, and trich ome staining methods. Groups were comparable in terms of gender, age and ty pe of gastrointestinal complaints. In the HM group, the most common parasit e was B. hominis. In this group, 23 patients (13%) had B. hominis, while in the control group only 2 patients (1%) had B. hominis. This difference was statistically significant (P < 0.05). Symptoms were non-specific for B. ho minis or other parasites in the HM group. The predominant symptoms in both groups were abdominal pain (87-89.5%), diarrhea (70-89.5%), and flatulence (74-68.4%). Although all patients with HM were symptom-free at the end of t reatment with oral metranidazol (1,500 mg per day for 10 days) 2 patients w ith HM had positive stool samples containing an insignificant number of par asites (< 5 cells per field). In conclusion, it appears that B. hominis is not rare and should be conside red in patients with HM who have gastrointestinal complaints while being tr eated with chemotherapy. Furthermore, metranidazol appears to be effective in treating B. hominis infection.