Comparison between different methods of Blastocystis hominis detection in stool samples.

Abstract

 Blastocystis hominis is common protozoan in human intestinal tract and can cause so-called

blastocystosis characterized by diarrhea. Its routine identification in clinical laboratories is

made by detection of vacuolar form in stool samples using wet mount smears. The present

study was carried out with the aim of evaluating the effectiveness of different techniques

for diagnosis of  B. hominis in the stool samples from the patients attended Brack Hospital

and Medical Technology Department, Faculty of Engineering and Technology, Brack.

A total of 360 stool samples were collected form randomized patients, presenting different

genders and ages (121 males and 239 females ,and aged from less than one year to 90

years), residing in different localities of Wadi Al-shati province. All specimens were

examined by direct smear microscopy (normal saline, iodine, and eosin stains),

concentration (formalin–ether sedimentation) and two xenic culture systems (Monophasic

Jone’s medium and Diphasic Boeck and Drbohlav's ) for the detection of  B. hominis. The

results highlights the low sensitivity of direct smear microscopy (11.29%) compared to

concentration method (15.5%) and  in-vitro culture methods (22.60%). There was no

significant difference (p>0.05) between direct smear preparations, and concentration

method, meanwhile there was significant difference (p<0.05) between direct smear

preparations and the two xenic culture systems for the detection of  B. hominis. There was

an almost equal numbers of positive samples in both culture techniques (85 samples in

diphasic medium and 78 in monophasic medium), and no significant difference (P>0.05)

was found between the two culture methods. Diphasic Boeck and Drbohlav’s medium

produced highest numbers (7.600±6.379) of  B. hominis cells compared to Monophasic

Jone’s medium (5.051±4.938) after every passage cultures and only the vacuolar

morphologic type of this organism was found in both culture systems. Moreover, a larger

size of vacuolar stage of  B. hominis detected in Diphasic Boeck and Drbohlav's medium,

than in Monophasic Jone's medium.

In vitro cultivation does seem worthwhile in the detection of  B. hominis in diagnostic

laboratories. Of all the diagnostic techniques used, diphasic Boeck and Drbohlav's medium

was the most sensitive method for detecting  B. hominis in stool specimens.

The short-term  in vitro culture methods achieved the best performance with regard to

sensitivity with other studied methods. With the advantages in terms of sensitivity, the  in

vitro culture methods could be applied to identify  B. hominis for both clinical diagnosis and

field study purposes, thus indicating the need to include laboratory techniques that enable

 B. hominis detection on a routine basis.