Comparison of methods for detecting Blastocystis hominis

Abstract

In order to determine the comparative sensitivity of two methods of detecting Blastocystis hominis and to investigate the seasonality of infection with this enteric protozoan parasite, the present study was conducted. In each of two 3-month periods representing winter, spring (February-April) and summer (July-September), 500 routine stool submissions were examined for B. hominis using microscopy following either formol-ether concentration or in vitro culture using Jones' medium. The organism was detected in 39 of the 1,000 samples investigated using the in vitro culture technique and in none of the samples using the formol-ether concentration technique. In 82% of the B. hominis-positive samples, no concurrent bacterial or parasitic pathogens were found, and diarrhoea was the most commonly recorded symptom among patients. Infection was more prevalent in summer than in winter/spring, occurring primarily in the 71-80-year age group. Cysts were detected in 20.5% of positive samples, but only following Ficoll-Paque concentration of formol-ether concentrates. Cyst excretion was more prevalent in summer than in winter/spring.

Direct characterization of Blastocystis from faeces by PCR and evidence of zoonotic potential

“…An advantage of the in vitro culture method is that low numbers of Blastocystis can be cultured for use in other (e.g., genotypic and/or phenotypic) tests (Suresh and Smith, 2004). A previous study comparing detection methods for the diagnosis of Blastocystis infections revealed that out of 23 Blastocystis positive samples, 98 % and 52 % were positive using in vitro culture and PCR detection directly from the faeces, respectively (Termmathurapoj et al 2004).…”

“…In previous studies using Jones' medium supplemented with 10 % horse serum (Salim et al 1999 ;Leelayoova et al 2002 ;Suresh and Smith, 2004 ;Termmathurapoj et al 2004 ;Yakoob et al 2004 ;Yoshikawa et al 2004 c), only human faecal samples were screened for Blastocystis. However, several different types of media to cultivate Blastocystis have been reported, and it has been suggested that the usefulness of cultivation may depend on the reagents and protocols employed (Zaman and Khan, 1994 ;Leelayoova et al 2002).…”

“…Fifty mg of fresh faecal material was inoculated into a sterile screw-top tube containing 3 ml of Jones' medium supplemented with 10 % horse serum (Jones, 1946 ;Suresh and Smith, 2004). Each sample was cultured in duplicate and incubated at 37 xC for 24-48 h. The cultures were examined for the presence of various morphological forms of Blastocystis using light microscopy at 400r magnification.…”

“…There are several methods used to detect Blastocystis infections, which include wet smears, concentration methods and in vitro amplification which was recently shown to be the most sensitive method to detect Blastocystis from faecal samples (Zaman and Khan, 1994 ;Leelayoova et al 2002 ;Suresh and Smith, 2004 ;Termmathurapoj et al 2004). However, due to the variable morphological forms that Blastocystis exhibits, it is impossible to distinguish among different species and subspecies of Blastocystis solely based on morphology without the use of molecular techniques (Yoshikawa et al 2004 b).…”

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

“…The use of xenic cultures, in which Blastocystis is grown in vitro with non-specific microorganisms, has been shown to be more sensitive in detecting Blastocystis but it is not commonly used in the diagnostic laboratory. [9][10][11] Molecular diagnosis by polymerase chain reaction (PCR) using the small subunit (SSU) ribosomal RNA gene is becoming more widely used for detection of enteric parasites. Although this technique is more costly, it is known to be more sensitive than the direct smear and xenic culture.…”