Detection of Isospora belli by polymerase chain reaction using primers based on small-subunit ribosomal RNA sequences

The aim of the present study was to use small-subunit (SSU)-rRNA sequences of Isospora belli to design specific primer pairs and a hybridization probe for the detection of Isospora belli in human samples by PCR and Southern b lot hybridization. PCR amplification with the primer pairs produced correct DNA fragments with target DNA from samples of Isospora belli-infected pati ents and from cloned SSU-rRNA of Isospora belli. The nature of the PCR prod ucts was confirmed by Southern blot hybridization. No amplification was see n with template DNA extracted from other parasites. Although Isospora belli infections can be easily diagnosed using light microscopy, molecular-based techniques may prove useful as an additional diagnostic tool.