Analysis of the Fecal Microbiota of Irritable Bowel Syndrome Patients and Healthy Controls with Real-Time PCR

OBJECTIVE The gut microbiota may contribute to the onset and maintenance of irritable bowel syndrome (IBS). In this study, the microbiotas of patients suffering from IBS were compared with a control group devoid of gastrointestinal (GI) symptoms. METHODS Fecal microbiota of patients (n = 27) fulfilling the Rome II criteria for IBS was compared with age- and gender-matched control subjects (n = 22). Fecal samples were obtained at 3 months intervals. Total bacterial DNA was analyzed by 20 quantitative real-time PCR assays covering approximately 300 bacterial species. RESULTS Extensive individual variation was observed in the GI microbiota among both the IBS- and control groups. Sorting of the IBS patients according to the symptom subtypes (diarrhea, constipation, and alternating predominant type) revealed that lower amounts of Lactobacillus spp. were present in the samples of diarrhea predominant IBS patients wheras constipation predominant IBS patients carried increased amounts of Veillonella spp. Average results from three fecal samples suggested differences in the Clostridium coccoides subgroup and Bifidobacterium catenulatum group between IBS patients (n = 21) and controls (n = 15). Of the intestinal pathogens earlier associated with IBS, no indications of Helicobacter spp. or Clostridium difficile were found whereas one case of Campylobacter jejuni was identified by sequencing. CONCLUSIONS With these real-time PCR assays, quantitative alterations in the GI microbiota of IBS patients were found. Increasing microbial DNA sequence information will further allow designing of new real-time PCR assays for a more extensive analysis of intestinal microbes in IBS.