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Journal of Clinical Microbiology, May 2005, p. 2375-2379, Vol. 43, No. 5
0095-1137/05/$08.00+0     doi:10.1128/JCM.43.5.2375-2379.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Detection of Cyclospora cayetanensis Oocysts in Human Fecal Specimens by Flow Cytometry

Brent R. Dixon,1* Jeff M. Bussey,1 Lorna J. Parrington,1 and Monique Parenteau2

Microbiology Research Division, Bureau of Microbial Hazards, Food Directorate, Health Products and Food Branch, Health Canada,1 Animal Resources Division, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada2

Received 5 August 2004/ Returned for modification 6 October 2004/ Accepted 24 January 2005

A diagnosis of cyclosporiasis typically involves stool examinations for the presence of Cyclospora oocysts by means of microscopy. In recent years, flow cytometry has been gaining in popularity as a novel method of detecting pathogens in environmental and clinical samples. The present study is an evaluation of a flow cytometric method for the detection and enumeration of Cyclospora oocysts in human fecal specimens associated with food-borne outbreaks of cyclosporiasis in Ontario, Canada. Flow cytometry results were generally very comparable to the original microscopy results for these specimens, in terms of both presence or absence of oocysts and relative oocyst concentrations. Of the 34 fecal specimens confirmed positive for Cyclospora by microscopy, 32 were also found positive by flow cytometry, and 2 others were considered equivocal. Of the eight fecal specimens reported to be negative by microscopy, two were found positive by flow cytometry and five others were considered equivocal. These two flow cytometry-positive samples and one of the equivocal samples were confirmed by microscopic reexamination, suggesting that flow cytometry may be more sensitive than microscopy. While the sample preparation time for flow cytometry is similar to or slightly longer than that for microscopy, the actual analysis time is much shorter. Further, because flow cytometry is largely automated, an analyst's levels of fatigue and expertise will not influence results. Flow cytometry appears to be a useful alternative to microscopy for the screening of large numbers of stool specimens for Cyclospora oocysts, such as in an outbreak situation.

* Corresponding author. Mailing address: Microbiology Research Division, 4th Flr. West, Banting Research Centre, Tunney's Pasture, Ottawa, Ontario, Canada K1A 0L2, Postal Locator 2204A2. Phone: (613) 957-0904. Fax: (613) 941-0280. E-mail: Brent_Dixon{at}hc-sc.gc.ca.

Journal of Clinical Microbiology, May 2005, p. 2375-2379, Vol. 43, No. 5
0095-1137/05/$08.00+0     doi:10.1128/JCM.43.5.2375-2379.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Uehlinger, F. D., Barkema, H. W., O'Handley, R. M., Parenteau, M., Parrington, L. J., VanLeeuwen, J. A., Dixon, B. R. (2008). Comparison of flow cytometry and immunofluorescence microscopy for the detection of Giardia duodenalis in bovine fecal samples. jvdi 20: 178-185 [Abstract] [Full Text]  


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