ARTICLE a b a b
Wet preparations of a) B. hominis and b) D. fragilis (original magnification x50).
a b
Comparison of D. fragilis staining: a) acridine orange; b) Rapid Diff-3 kit (original magnification x50).
a b
Comparison of B. hominis staining: a) acridine orange; b) Rapid Diff-3 kit (original magnification x50).
co-infection by D. fragilis and B. hominis was only seen in females of a similar age and pure D. fragilis infection was only seen in males of a similar age who were immunocompromised and receiving cancer treatment
The acridine orange stain proved effective in detecting G. lamblia, identifying 100% (n=8) of the parasites compared with 75% (n=6) for the Rapid Diff-3 kit. These results were confirmed using an ELISA assay.
DISCUSSION D. fragilis prevalence was within range for a developed country (2%) whereas that for B. hominis was slightly lower (2.5%), perhaps because the majority of patients in the cohort were hospital patients; if the study was expanded to include more GP patients then this level might increase. Acridine orange performed better overall than did the Rapid Diff-3 kit, and detected more target organisms plus a wide range of other enteric parasites. Therefore, the commercial
Patient variables analysed. Variable Pearson χ2
Sample type
Laboratory procedure Patient type
Clinical details
Additional organisms isolated Gender
Immunocompromised status 0.98
0.532 0.233 0.465 0
0.235
Comparison of Giardia lamblia staining: a) acridine orange; b) Rapid Diff-3 kit (original magnification x50).
kit would only be ideal if used specifically for D. fragilis. Few correlations were identified among the patient variables. What is interesting to note is that co-infection was only seen in female patients, and D. fragilis was only isolated in males receiving cancer treatment and was not isolated in any patient under the age of 28, thus questioning any link with children.
In conclusion, acridine orange proved to
be an excellent screening stain for enteric parasites such as D. fragilis and B. hominis, and would be especially useful in laboratories that do not use an ELISA method for the detection of G. lamblia.
REFERENCES 1 World Health Organization. Parasitic diseases. Geneva: WHO, 2012 (
www.who.int/vaccine_research/diseases/ soa_parasitic/en/
index.html).
2 Tan TC, Suresh KG. Predominance of amoeboid forms of Blastocystis hominis
Likelihood ratio
0.981 0.989 0.247 0.998 0.393 0.122
Age 0.966 1 0.091
0.037
Linear-by-linear association
0.339 0.558 0.294 0.098 0.707 0.772 0.576 0.678
in isolates from symptomatic patients. Parasitol Res 2006; 98 (3): 189–93.
3 Barratt J, Harkness J, Marriott D, Ellis JT, Stark D. The ambiguous life of Dientamoeba fragilis: the need to investigate current hypotheses on transmission. Parasitology 2011; 138 (5): 557–72.
4 Windsor JJ, Macfarlane L, Hughes-Thapa G, Jones SK, Whiteside TM. Detection of Dientamoeba fragilis by culture. Br J Biomed Sci 2003; 60 (2): 79–83.
5 Windsor JJ, Bamber AI, Macfarlane L. Detection of Dientamoeba fragilis and Blastocystis hominis using a simple staining method. Br J Biomed Sci 2006; 63 (1): 27–8.
6 Yakoob J, Jafri W, Beg MA et al. Blastocystis hominis and Dientamoeba fragilis in patients fulfilling irritable bowel syndrome criteria. Parasitol Res 2010; 107 (3): 679–84.
7 Stark D, van Hal S, Marriott D, Ellis J, Harkness J. Irritable bowel syndrome: a review on the role of intestinal protozoa and the importance of their detection and diagnosis. Int J Parasitol 2007; 37 (1): 11–20.
8 Johnson EH, Windsor JJ, Clark CG. Emerging from obscurity: biological, clinical, and diagnostic aspects of Dientamoeba fragilis. Clin Microbiol Rev 2004; 17 (3): 553–70.
Lisa Toole MIBMS presented this work as a poster at the recent IBMS Biomedical Science Congress at the International Convention Centre in Birmingham.
DECEMBER 2013
THE BIOMEDICAL SCIENTIST
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