Genomic analysis of Blastocystis hominis isolates in patients with HIV-positive using locus SSU-rDNA.

Blastocystis hominis (B. hominis) is a protozoan zoonosis which clinical signs of infection with this parasite has been reported to be more severe in patients with weakened immune systems than healthy controls. So, the aim of the study was to evaluate genomic analysis of B. hominis isolates obtained from patients with HIV-positive using locus SSU-rDNA. At first, 268 stool samples were randomly collected from patients with HIV-positive referred to health centers of Khuzestan province, southwest of Iran. Formol-ether and direct smear techniques were used for the detection of parasitic agents. After extracting DNA, the samples were analyzed by the PCR method. Finally, the subtypes were determined by the sequencing and PCR methods. New samples were used for the preparation of positive control sample; they were cultured in coagulant-serum biphasic cultivation media. Of 268 stool samples, 33 (12.3%) cases were detected positive for B. hominis using Formol-Ether technique but 51 (19%) cases were positive using molecular method. The most common isolates were related to the subtype III with 29 positive cases (56.8%), then, genotype I with 11 (21.6%) cases, 6 cases (11.8%) with genotype II, 3 (5.9%) combined cases with genotypes I and III as well as 2 cases (3.9%) with genotype VI. There was a significant difference between two groups of HIV-positive patients (infected with the parasite and/or without the parasite) in the term of the mean of TCD4-positive cells. The results indicated a relatively high prevalence of B. hominis in HIV-positive patients as well as our findings may represent that the number reduction of TCD4-positive cells has an effective role in the increased risk of the parasitic infection in HIV-positive patients.