Microscopic detection of Giardia trophozoites in archival pathology specimens of human small intestine: light microscopy, low voltge SEM, and confocal scanning laser microscopy using fluorescent in situ hybridization

Abstract

In situ hybridization methods have been widely used for the analysis of chromosomal markers, and for the detection and identification of various species of bacteria in environmental samples. In situ hybridization probes to ribosomal RNA have been used as a diagnostic tool for the study of various parasitic protozoa, and fluorescent in situ hybridization (FISH) probes have been used to study the intracellular distribution of mRNA.The intestinal protozoan, Giardia, colonizes the small intestine of a variety of different animals, including humans, and forms an infective cyst stage which is responsible for host-to-host transmission. Light microscopic detection in environmental or fecal samples has relied on the detection of cysts whose presence may be infrequent. In human giardiasis, confirmation of diagnosis has often required microscopic analysis of intestinal biopsies for detection of trophozoites. Analysis of the molecular sequence of 16s rDNA (small subunit) in Giardia isolates has permitted the development of species specific probes for Giardia.