Subtype identification of Blastocystis spp. isolated from patients in a major hospital in northeastern Thailand

Subtype identification of Blastocystis spp. isolated from patients in a major hospital in northeastern Thailand

Parasitology Research, December 2012

23224731

Sarinee Jantermtor, Porntip Pinlaor, Kookwan Sawadpanich, Somchai Pinlaor, Arunnee Sangka, Chotechana Wilailuckana, Wachanan Wongsena, Hisao Yoshikawa

The present study is aimed to identify the prevalence of Blastocystis subtypes isolated from patients in a major hospital in northeastern Thailand. A total of 562 stool samples were examined by culture technique, and 56 Blastocystis-positive samples were analyzed further by the combination of restriction fragment length polymorphism (RFLP) followed by polymerase chain reaction with sequence-tagged site primers (PCR-STS). By RFLP profiles, Blastocystis genotypes were categorized into four groups: group A (12, 21.4%), group B (32, 57.1%), group C (10, 17.9%), and group D (2, 3.6%). By PCR-STS, only four subtypes were identified. All 12 (21.4%) isolates in group A were identified as subtype 1. Similarly, all 32 (57.1%) isolates in group B were subtype 3. In group C, 10 (17.9%) samples were all subtype 7, and two samples (3.6%) in group D were both subtype 6. Of 56 Blastocystis-positive patients, 31 (55.4%) were asymptomatic and 22 (39.4%) have gastrointestinal symptoms. No significant association was observed between the Blastocystis subtypes and the clinical features. Among the Blastocystis-positive patients, the most characteristic stool samples were loose (78.6%) and soft (17.9%). In conclusion, the most common Blastocystis spp. in northeastern Thailand was subtype 3 followed by subtype 1. Relatively minor subtypes, subtype 6 and subtype 7 which are considered as avian subtypes, were found for the first time in humans in Thailand.