Genomic polymorphism among Blastocystis hominis strains and development of subtype-specific diagnostic primers.

Genomic polymorphisms among nine strains of Blastocystis hominis were examined by random amplified polymorphic DNA (RAPD) using four different arbitrary polymerase chain reaction (PCR) primers. Based on the RAPD patterns, nine strains were classified into three groups. The specific primers designed from the unique bands yielded a single band from within each same group, but did not amplify between all the groups examined. Specificity of these diagnostic primers was tested against several common intestinal parasites and a yeast, and no amplification was confirmed. Since the current criteria indicates that Blastocystis organisms isolated from humans are designated as B. hominis, the authors propose to classify several subtypes among B. hominis groups based on the difference of genomic DNA using three diagnostic primers.