Subtypes of Blastocystis sp. isolated in fecal samples from transplant candidates in São Paulo, Brazil

Blastocystis sp. is an intestinal protozoan commonly found in fecal samples of many animal species, including humans, but poorly studied in transplant candidates. The aim of this study was to evaluate the occurrence and molecular identification of Blastocystis sp. in fecal samples from transplant candidates. A polymerase chain reaction was performed using specific primers for Blastocystis ribosomal DNA. The DNA sequences obtained were aligned and compared with other sequences from the GenBank and MLST databases. The analyzed samples showed a positivity of 16% (24 of 150) for Blastocystis sp. The highest occurrence was observed in renal transplant candidates (31.4%), followed by hepatic transplant candidates (10.4%) and candidates for bone marrow transplantation (5.9%). Subtype (ST) 3 (45.8%) was the most prevalent among the isolates, followed by ST1 (37.5%), ST2 (12.5%), and ST7 (4.2%). This is the first study of molecular identification Blastocystis sp. in transplant candidates. Our results confirmed that ST3 was the most common subtype in transplant candidates and reinforce the importance of new studies to investigate of Blastocystis sp. in these patients.