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 blot hybridization. PCR amplification with the primer pairs produced correct DNA fragments with target DNA from samples of Isospora belli-infected patients and from cloned SSU-rRNA of Isospora belli. The nature of the PCR products was confirmed by Southern blot hybridization. No amplification was seen 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.