Comparison of microscopy, culture, and conventional polymerase chain reaction for detection of blastocystis sp. in clinical stool samples

Am J Trop Med Hyg. 2011 Feb;84(2):308-12. doi: 10.4269/ajtmh.2011.10-0447.


We tested 513 stool samples from patients in Sydney, Australia for Blastocystis by using five diagnostic techniques: microscopy of a permanently stained smear using a modified iron-hematoxylin stain, two xenic culture systems (a modified Boeck and Drbohlav's medium and tryptone, yeast extract, glucose, methionine-9 medium), and two published conventional polymerase chain reaction methods specific for the small subunit ribosomal DNA. Ninety-eight (19%) samples were positive for Blastocystis in one or more of the diagnostic techniques. The PCR 2 method was the most sensitive at detecting Blastocystis with a sensitivity of 94%, and the least sensitive was microscopy of the permanent stain (48%). Subtype 3 was the most predominant subtype (present in 43% of samples assigned to this group). This study highlights the low sensitivity of microscopy when used as the sole diagnostic modality for detection of Blastocystis sp.

Publication types

  • Comparative Study

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Blastocystis Infections / diagnosis*
  • Blastocystis Infections / parasitology
  • Blastocystis* / genetics
  • Blastocystis* / growth & development
  • Blastocystis* / ultrastructure
  • Cell Culture Techniques / methods
  • Child
  • Child, Preschool
  • Coloring Agents
  • Culture Media
  • DNA, Protozoan / genetics
  • Feces / parasitology*
  • Female
  • Humans
  • Infant
  • Male
  • Microscopy / methods
  • Middle Aged
  • Polymerase Chain Reaction / methods
  • Sensitivity and Specificity
  • Sequence Analysis, DNA
  • Young Adult


  • Coloring Agents
  • Culture Media
  • DNA, Protozoan