Real-time PCR analysis of enteric pathogens from fecal samples of irritable bowel syndrome subjects

Growing amount of scientific evidence suggests that microbes are involved in the pathophysiology of irritable bowel syndrome (IBS). The predominant fecal microbiota composition of IBS subjects has been widely studied with DNA-based techniques but less research has been focused on the intestinal pathogens in this disorder. Here, we optimized a highly sensitive panel of 12 quantitative real-time PCR (qPCR) assays to shed light on the putative presence of intestinal pathogens in IBS sufferers. The panel was used to screen fecal samples from 96 IBS subjects and 23 healthy controls.

Fifteen IBS samples (17%) tested positive for Staphylococcus aureus with a thermonuclease (nuc) gene-targeting qPCR assay, whereas none of the healthy controls were positive for S. aureus (p <0.05). The S. aureus -positive IBS samples were confirmed by sequencing of the PCR amplicons. Clostridium perfringens was detected from IBS and control groups with a similar frequency (13% and 17%, respectively) with α-toxin (plc) gene -targeting qPCR assay while none of the samples tested positive for the Cl. perfringens enterotoxin-encoding gene (cpe).

The qPCR panel consisting of 12 assays for an extensive set of pathogenic microorganisms provides an efficient alternative to the conventional detection of gastrointestinal pathogens and could accelerate the initiation of targeted antibiotic therapy reducing the risk of post-infectious IBS (PI-IBS). S. aureus has not been previously reported to be associated with the onset of IBS. Although we discovered significant differences in the prevalence of S. aureus between the study groups, its importance in giving rise to IBS symptoms requires further studies.