OBJECTIVE:

Irritable bowel syndrome after gastroenteritis is well recognized. Our aim was to determine whether postinfective IBS (PI-IBS) has histological or clinical features that are distinct from those of IBS patients with no history of preceding infection.

METHODS:

A total of 75 consecutive IBS outpatients and 36 healthy control subjects completed a questionnaire detailing symptoms, mode of onset, and previous psychiatric history. All underwent a full diagnostic workup including rectal biopsy, which included immunostaining and quantification for lamina propria or intraepithelial T lymphocytes, serotonin-containing enterochromaffin (EC), and mast cells. Patients were divided according to onset of symptoms into PI-IBS (n= 23) or non–PI-IBS (n= 52) patients.

RESULTS:

Diarrhea predominance occurred more frequently in PI-IBS (70%) than in non–PI-IBS (42%) patients (p= 0.03). A history of previous treatment for anxiety or depression was present in 26% of PI-IBS patients compared to 54% of non–PI-IBS (p= 0.02). Biopsy results for all patients were normal using conventional criteria; however, quantification revealed that PI-IBS showed increased EC cells compared to those of non–PI-IBS patients (p= 0.017) and controls (p= 0.02). Lamina propria T lymphocytes were increased in PI-IBS (p= 0.026) and non–PI-IBS (p= 0.011) patients compared to controls. Mast cells were increased in non–PI-IBS patients (p= 0.054) compared to controls.

CONCLUSIONS:

Individuals with PI-IBS are a clinically distinct subgroup characterized by diarrheal symptoms, less psychiatric illness, and increased serotonin-containing EC cells compared to those with non–PI-IBS.