Comparison of Microscopy, Culture, and Conventional Polymerase Chain Reaction for Detection of Blastocystis sp. in Clinical Stool Samples

Abstract

Abstract. 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.

The Prevalence of Blastocystis hominis and Other Protozoan Parasites in Soldiers Returning from Peacekeeping Missions

“…The difference in prevalence of B. hominis infections between these populations may be caused by the different diagnostic methods used 7 as well as the soldiers being stationed in different areas under different sanitary conditions.…”

“…5 Although this protozoan is a nonpathogenic commensal, both in vivo and in vitro studies have shown its pathogenic power. 6,7 In symptomatic patients, the clinical consequences of B. hominis infection include abdominal pain, nausea, vomiting, anorexia, flatulence, weight loss, and acute or chronic diarrhea. 8,9 In recent years, armed conflicts have been relatively frequent, especially in areas of the Middle East, during which peacekeepers are being exposed to multiple risks to their health and life, including gastrointestinal protozoan infections.…”

Prevalence and Risk Factors for Blastocystis Infection Among Children and Caregivers in a Child Care Center, Bangkok, Thailand

“…2,5,13 The variations of the prevalence of parasitic infection including Blastocystis infection might depend on the study population or geographic location, age, 14 and detection methods. 15,16 Using PCR technique, the highest prevalence of Blastocystis infection was found among children of Senegal River Basin, which was 100%. 17 In this study, direct wet smear and in vitro cultivation were used as screening detection methods.…”

“…in the stool samples because many inhibitor substances were found in the stool samples and PCR sensitivity depends on specific primers and the quality of Taq DNA polymerase. 16 Moreover, DNA extraction from stool samples by commercial kits was not very well achieved. Yoshikawa and others 18 indicated different sensitivities among the DNA extraction from commercial kits and that fecal culture method was useful to obtain a high detection rate with low cost performance to identify Blastocystis sp.…”

Update on the Molecular Epidemiology and Diagnostic Tools for Blastocystis sp

“…Due to varying modes of diagnostic techniques used in epidemiological studies of Blastocystis, it is difficult to determine the actual prevalence of Blastocystis due to some studies relying solely on microscopy for diagnosis. It was shown that molecular techniques have the highest sensitivity rates for diagnosis of this organism [30,31] and the use of only microscopy in diagnosis and epidemiological studies limits interpretation of data on prevalence of Blastocystis infections.…”