DIAGNOSTIC UTILITY OF POLYMERASE CHAIN REACTIONIN GIARDIASIS
Mamdouh Hegazy, Aya Handousa, Hossam EL-Nemr, Ayda Awad, Mohamed El-Malky, Soha Awad, and Ahmed Settin*
Departments of Medical Parasitology and *Pediatrics and Genetics,Faculty of Medicine, Mansoura University
Copro-microscopy using both the direct smear and the formol-ether sedimentation concentration techniques diagnosed Giardia intestinalis in 164 (44.6%) of 368 fecal samples. Of copro-microscopy-positive samples, 94.7% showed positive copro-antigen detection by ELISA and only 75% showed positive duodenal fluid microscopy. On the other hand, in all Giardia positive cases, Giardia DNAs from stool and duodenal fluid samples could be amplified by the polymerase chain reaction using primers targeting the triose phosphate isomerase (tpi) gene. The detection threshold of Giardia intestinalis by copro-microscopy was very high (2000 cysts/g stool), compared to the low detection threshold (10 cysts/g stool) of the polymerase chain reaction. This is the first report to quantify the detection threshold of Giardia intestinalis using polymerase chain reaction and to show its higher sensitivity over the traditional copro-microscopy.